TWI859246B - Base material with insulating resin layer, laminate using same, and method for manufacturing laminate - Google Patents

Abstract

A base material with an insulating resin layer, comprising a base material, a first resin layer which is disposed on the base material and has a thickness reduction of less than 30% upon molding for 60 minutes at 220℃ under pressurizing conditions of 3.0 MPa, and a second resin layer disposed on the first resin layer.

Description

A substrate with an insulating resin layer, a laminate using the substrate, and a method for manufacturing the laminate

The present invention relates to a substrate with an insulating resin layer, a laminate using the substrate, and a method for manufacturing the laminate.

In recent years, the semiconductor packages widely used in electronic equipment, communication equipment and personal computers have been increasingly advanced in functionality and miniaturization. In addition, along with such technological development, there is a demand for thinner printed wiring boards and substrates for mounting semiconductor components in semiconductor packages.

Regarding the manufacturing method of a thin printed wiring board and a semiconductor element mounting substrate, there is disclosed a method of manufacturing a thin printed wiring board by forming a copper layer that can be peeled off in a subsequent step on a highly rigid and thick supporting substrate (carrier substrate) such as stainless steel, forming a circuit pattern on a laminate by pattern plating, laminating an insulating layer such as epoxy-coated glass fiber and performing a heating and pressure treatment, and finally peeling and removing the supporting substrate (for example, refer to patent document 1). By laminating the circuit pattern and the insulating material on a high-rigidity and thick supporting substrate and finally peeling and removing the supporting substrate, thin printed wiring boards and semiconductor component mounting substrates can be manufactured even with existing manufacturing equipment.

In addition, as for the resin sheets used for these printed wiring boards, there are known sheets formed by multi-layering resin components. As for such technology, there are known insulating resin sheets that suppress the etching amount of each layer in order to improve the performance of the multi-layered thin film (for example, refer to Patent Document 2). [Prior Technical Document] [Patent Document]

[Patent Document 1] Japanese Patent Publication No. 59-500341 [Patent Document 2] Japanese Patent Publication No. 2017-50561

[The problem that the invention wants to solve]

The film described in Patent Document 2 is intended to adjust the etching amount of each layer to solve the problem of via shape made by laser processing. However, the necessary condition of the film is that the total thickness of each layer is 12μm or more. Therefore, there is a need to develop a technology that can be thinner (for example, less than 10μm) and can meet the requirements of insulation and embedding properties of patterned conductive layers (hereinafter sometimes referred to as "embedding properties").

The present invention aims to solve the above-mentioned problems and provides a substrate with an insulating resin layer having excellent insulation and landfill properties, as well as a laminate using the substrate and a method for manufacturing the laminate. [Means for solving the problem]

That is, the present invention is as follows. ＜1＞ A substrate with an insulating resin layer, comprising: a substrate, a first resin layer disposed on the substrate, and having a thickness reduction of less than 30% when formed under a pressure of 220°C and 3.0 MPa for 60 minutes, and a second resin layer disposed on the first resin layer. ＜2＞ A substrate with an insulating resin layer as in ＜1＞, wherein the minimum melt viscosity of the second resin layer is less than 100,000 Pa･s. ＜3＞ A substrate with an insulating resin layer as in ＜1＞ or ＜2＞, wherein the thickness of the first resin layer is less than 10μm. <4> A substrate with an insulating resin layer as described in any one of <1> to <3>, wherein the thickness of the second resin layer is 2.0 μm or more. <5> A substrate with an insulating resin layer as described in any one of <1> to <4>, wherein the combined thickness of the first resin layer and the second resin layer is 3 μm or more and 20 μm or less. <6> A substrate with an insulating resin layer as described in any one of <1> to <5>, wherein the first resin layer contains at least one selected from the group consisting of polyimide, liquid crystal polyester, epoxy resin, cyanate compound, maleimide compound, phenolic resin, thermosetting modified polyphenylene ether resin, benzophenone compound, organic modified polysiloxane and a compound having a polymerizable unsaturated group. <7> A substrate with an insulating resin layer as described in any one of <1> to <6>, wherein the second resin layer contains at least one selected from the group consisting of epoxy resin, cyanate compound, maleimide compound, phenolic resin, thermosetting modified polyphenylene ether resin, benzophenone compound, organic modified polysiloxane compound and compound having polymerizable unsaturated group. <8> A substrate with an insulating resin layer as described in any one of <1> to <7> is used for the production of a coreless substrate provided on a printed wiring board or a semiconductor element mounting substrate. <9> A substrate with an insulating resin layer as described in <8>, wherein the coreless substrate is a 3-layer coreless substrate. <10> A laminate having a stacking layer, the stacking layer being a stacking layer of a conductive layer and an insulating layer formed by using a substrate with an insulating resin layer as in any one of claims <1> to <9>. <11> A laminate as in <10>, wherein the thickness of at least one insulating layer is 1 μm or more and less than 15 μm. <12> A laminate as in <10> or <11>, wherein the stacking layer has a plurality of conductive layers and insulating layers, and the conductive layers are arranged between each insulating layer and on the surface of the outermost layer of the stacking layer. <13> A stacked body as described in any one of <10> to <12>, wherein the conductive layer and the insulating layer are alternately stacked in the stacked layer, and the stacked layer has 3 or 4 insulating layers. <14> A stacked body as described in any one of <10> to <13> is a coreless substrate. <15> A method for manufacturing a stacked body, comprising the step of forming a stacked layer consisting of the conductive layer and the insulating layer by forming an insulating layer on the surface of the conductive layer using a substrate with an insulating resin layer as described in any one of <1> to <9>. <16> A method for manufacturing a stacked body as in <15>, wherein the thickness of at least one of the insulating layers is greater than 1 μm and less than 15 μm. <17> A method for manufacturing a stacked body as in <15> or <16>, wherein the stacked layer has a plurality of conductive layers and insulating layers, and the conductive layers are disposed between each insulating layer and on the surface of the outermost layer of the stacked layer. <18> A method for manufacturing a stacked body as in any one of <15> to <17>, wherein the insulating layer has 3 or 4 layers. <19> A method for manufacturing a laminate as described in any one of <15> to <18>, wherein the laminate is a coreless substrate. [Effect of the invention]

According to the present invention, a substrate with an insulating resin layer having excellent insulation and filling properties, a laminate using the substrate, and a method for manufacturing the laminate can be provided.

Hereinafter, the form for implementing the present invention (hereinafter referred to as "the present embodiment") will be described in detail with reference to the drawings as needed, but the present invention is not limited to the following present embodiment. The present invention may have various modifications without departing from the main purpose. In this specification, the stacked body is formed by bonding each layer to each other, and the layers may also be removable from each other as needed. In addition, in the drawings, the same element is annotated with the same symbol, and repeated descriptions are omitted. In addition, the positional relationship such as up, down, left, and right, unless otherwise specified, is based on the positional relationship shown in the drawings. In addition, the dimensional ratio of the drawings is not limited to the ratio shown in the drawings. In addition, in this specification, "(meth)acrylic acid" means "acrylic acid" and its corresponding "methacrylic acid", and "(meth)acrylate" means "acrylate" and its corresponding "methacrylate".

In the present embodiment, "resin solid content" or "resin solid content in the insulating resin layer", unless otherwise specified, refers to the resin contained in the insulating resin layer or the resin composition and the components constituting the resin after curing. In addition, "100 parts by mass of the resin solid content" refers to the total of the resin in the insulating resin layer or the resin composition and the components constituting the resin after curing, which is 100 parts by mass.

[Substrate with insulating resin layer] The substrate with insulating resin layer of the present embodiment (hereinafter sometimes referred to as "substrate with resin layer") comprises: a substrate, a first resin layer disposed on the substrate and having a thickness reduction of less than 30% when formed under pressure conditions of 220°C and 3.0 MPa for 60 minutes (hereinafter sometimes referred to as "first resin layer"), and a second resin layer disposed on the first resin layer (hereinafter sometimes referred to as "second resin layer"). In addition, hereinafter, "the thickness reduction when formed under pressure conditions of 220°C and 3.0 MPa for 60 minutes" is sometimes referred to as "thickness reduction". Likewise, the first and second resin layers are sometimes collectively referred to as "resin layers in this embodiment."

The substrate with a resin layer of this embodiment has a first resin layer whose thickness is reduced by less than 30%, and a second resin layer. Here, the second resin layer is usually a layer containing a resin that is fluid during a press process, and the layer itself is also fluid during a press process. The second resin layer is usually a layer that fills one side of a member that forms a laminated body together with the substrate with a resin layer, and is in contact with the surface of the second resin layer (hereinafter, this layer is sometimes referred to as a "buried layer"). As for the above-mentioned components, for example, a conductive layer such as a circuit pattern provided on a substrate can be cited, and the conductive layer is equivalent to a convex portion in a concave-convex shape formed together with the substrate and is buried in the second resin. In addition, in order to maintain the insulation between the convex portion buried in the second resin layer and the substrate, the first resin layer is a layer that maintains the distance between the substrate and the second resin layer within a predetermined range after a pressing process such as when the laminate is formed. (Hereinafter, this layer is sometimes referred to as a "film thickness maintaining layer"). In other words, the first resin layer is a layer that separates the substrate and the second resin layer after a pressing process. The second resin layer functions as a embedding layer, and is therefore preferably a layer different from the first resin layer in at least one of the constituent components and physical properties. The first and second resin layers may be different in composition, physical properties, or a combination of these, but are not particularly limited. The first and second resin layers may be different in composition, such as using polyimide for the first resin layer and epoxy for the second resin layer. In the case of different physical properties, for example, the thickness reduction or the minimum melt viscosity can be achieved by adjusting the blending ratio of the components contained in each layer or the curing state. In order to adjust the curing state of the first and second resin layers, for example, the coating conditions of each layer can be changed so that the first resin layer is completely cured and the second resin layer is in a semi-cured state.

The base material with a resin layer of the present embodiment is useful, for example, as a material for forming an insulating layer provided on a conductive layer such as a circuit pattern. Such a material can be exemplified as a material for forming an insulating layer of a printed wiring board or a semiconductor component mounting substrate used in the manufacture of electronic equipment, communication equipment, and personal computers. For example, when manufacturing a printed wiring board, the base material with a resin layer of the present embodiment is arranged on a substrate having a conductive layer such as a circuit pattern formed thereon in such a manner that the second resin layer is in contact with the conductive layer, and then the first and second resin layers are hardened by heating and pressing (pressing), thereby forming an insulating layer on the conductive layer. At this time, the conductive layer like a circuit pattern is buried in the second resin layer. On the other hand, the thickness of the insulating layer existing on the conductive layer can be maintained within a predetermined range by the first resin layer. In this way, with the substrate with a resin layer of this embodiment, the first resin layer can function as a film thickness maintaining layer, and the second resin layer can function as a buried layer. In particular, in the substrate with a resin layer of this embodiment, the thickness of the first resin layer is reduced by less than 30%, so the thickness of the insulating layer itself can be maintained within the desired range even after pressing. Furthermore, the second resin layer can improve the fluidity of the resin during the pressing process, suppressing the gaps in the conductor layer such as the circuit pattern while burying it. As a result, the substrate with the resin layer in this embodiment can make the insulation in the thickness direction of the insulating layer excellent by maintaining the thickness of the insulating layer within the desired range, and can suppress the gaps in the insulating layer and fill the conductor layer.

[Substrate] As for the substrate, for example, there can be cited resin films such as polyethylene terephthalate (PET) film, polyimide film, polyamide film, polyester film, polybutylene terephthalate (PBT) film, polypropylene (PP) film, and polyethylene (PE) film, as well as metal foils such as copper foil, aluminum foil, and gold foil. As for the substrate in the present embodiment, for example, a substrate with a peel-off layer such as a resin film with a peel-off layer, a copper foil with a peel-off layer, etc. can also be used. The substrate can be peeled off from the first resin layer when the laminate is formed as needed, or in the case of using a metal foil such as copper foil, it can also be patterned and used as a conductive layer. Furthermore, the release layer may be, for example, a release layer provided on a conventional release-layer-attached substrate.

The substrate in this embodiment is not particularly limited, and is preferably a metal foil, more preferably a copper foil. As for the copper foil, a copper foil or a copper film used in a conventional printed wiring board can be used. As specific examples of the copper foil, electrolytic copper foil, rolled copper foil, and copper alloy film can be listed. The copper foil or copper film can also be subjected to known surface treatments such as matte treatment, corona treatment, nickel treatment, and cobalt treatment. As for the copper foil in this embodiment, commercially available products can also be used, for example, "GHY5" (trade name, 12μm thick copper foil) manufactured by JX Metal (Co., Ltd.), "3EC-VLP" (trade name, 12μm thick copper foil), "3EC-III" (trade name, 12μm thick copper foil) and "3EC-M2S-VLP" (trade name, 12μm thick copper foil) manufactured by Mitsui Mining and Co., Ltd., copper foil "GTS-MP" (trade name, 12μm thick copper foil) manufactured by Furukawa Electric Industries, Ltd., and "JXUT-I" (trade name, 1.5μm thick copper foil) manufactured by JX Metal (Co., Ltd.) can be used.

In order to improve the bonding strength between the copper foil and the resin layer in the present embodiment and prevent the layer from peeling off during long-term use, the arithmetic average roughness (Ra) of the copper foil surface is generally preferably not less than 0.05 μm and not more than 2 μm, and more preferably not less than 0.08 μm and not more than 1.7 μm. In order to obtain a better bonding between the copper foil and the resin layer in the present embodiment, the arithmetic average roughness (Ra) is particularly preferably not less than 0.2 μm and not more than 1.6 μm. In the present embodiment, a substrate having a copper foil with an arithmetic average roughness within the above range and an insulating resin layer can be ideally used in the manufacture of printed wiring boards with high-density fine wiring and substrates for mounting semiconductor components. The arithmetic mean roughness can be measured using a commercially available shape measurement microscope (laser microscope, for example, "VK-X210" (trade name) manufactured by KEYENCE CORPORATION).

The thickness of the substrate in this embodiment is not particularly limited as long as the effect of this embodiment can be exerted. For example, from the perspective of improving operability and reducing costs, it is preferably 5 μm or more and 200 μm or less, more preferably 10 μm or more and 150 μm or less, and even more preferably 15 μm or more and 80 μm or less. In addition, when a metal foil such as copper foil is provided as the substrate, the thickness is preferably 1 μm or more and 18 μm or less from the perspective of roughening the surface of the metal foil. In addition, from the perspective of ideally obtaining a thin printed wiring board and a substrate for mounting semiconductor components, the thickness of the substrate is more preferably 2 μm or more and 15 μm or less.

[First resin layer] In this embodiment, the thickness reduction of the first resin layer when formed at 220°C and 3.0 MPa for 60 minutes is less than 30%.

First, FIG. 1 is used to illustrate the reduction in thickness of the first resin layer in the present embodiment. FIG. 1 is a schematic diagram for illustrating the reduction in thickness of the first resin layer in the present embodiment. As shown in FIG. 1 (A), the substrate 10 with a resin layer is stacked in sequence and has a substrate 12, a first resin layer 14A, and a second resin layer 16A. Similarly, as shown in FIG. 1 (A), the inner circuit substrate 20 has a substrate 22 and a plurality of conductor layers 24 arranged on the substrate 22, and the conductor layers 24 form a circuit having a pattern shape. In the resin layer-attached substrate 10, the second resin layer 16A is arranged in contact with the surface of the inner circuit board 20 provided with the conductor layer 24, and then heated and pressed (pressed). After the pressing, a laminate 30 is formed as shown in FIG. 1 (B). The laminate 30 has an insulating layer 32 composed of a first resin layer 14B and a second resin layer 16B formed by curing the first resin layer 14A and the second resin layer 16A, respectively.

Here, in the first resin layer, "the thickness reduction when forming for 60 minutes under the conditions of 220°C and 3.0 MPa" is a value expressed as a percentage of the thickness reduction of the first resin layer after forming relative to the thickness of the first resin layer before forming. The thickness reduction is calculated from the thickness X of the first resin layer 14A before the pressing treatment and the thickness Y of the first resin layer 14B formed for 60 minutes (pressing treatment) under the conditions of 220°C and 3.0 MPa. For example, first, the thickness of the first resin layer (thickness X in FIG. 1 ) is measured from the cross section of the substrate 10 with the resin layer using a scanning electron microscope (SEM). Then, the laminate 30 is polished to expose a parallel cross section in the laminate to form a sample, and the thickness of the first resin layer (thickness Y in FIG. 1 ) is measured using a scanning electron microscope (SEM) for the obtained sample. After the measurement, the thickness X of the first resin layer 14A before pressing is compared with the thickness Y of the first resin layer 14B of the laminate 30 after pressing, and the amount of thickness reduction can be evaluated. Specifically, the thickness reduction amount (TΔ) of the first resin layer can be calculated using the following formula (1) from the thickness X of the first resin layer in the substrate with the resin layer attached in the form of a resin sheet, for example, and the thickness Y of the first resin layer in the laminated body in the form of a copper-clad laminated board, for example. Thickness reduction (%) = (X-Y)/X×100　　　(1) However, the thickness reduction of a resin layer made of the same material as the first resin layer 14A can be calculated in the same manner by clamping the resin layer with a flat sheet that does not deform under the following pressurization conditions and then subjecting it to forming (pressing treatment) for 60 minutes under the above pressurization conditions, and the thickness reduction is set as the thickness reduction of the first resin layer.

From the perspective of ensuring insulation, the thickness reduction of the first resin layer is less than 30%. If the thickness reduction of the first resin layer is more than 30%, the thickness of the first resin layer will be excessively reduced under the conditions of a press process such as forming at 220°C and 3.0 MPa for 60 minutes, and the insulation of the insulating layer will be reduced. As for the thickness reduction of the first resin layer, from the perspective of ensuring insulation, it is preferably less than 28%, preferably less than 25%, preferably less than 20%, more preferably less than 10%, and particularly preferably 0%. In addition, the lower limit of the thickness reduction is not particularly limited, and it may also be 0%. The thickness reduction of the first resin layer can be adjusted to a desired value by appropriately selecting the type of thermosetting resin contained therein, controlling the curing degree of the resin, or adding inorganic fillers.

The thickness of the first resin layer is not particularly limited, but from the perspective of thinner film, it is preferably less than 10 μm. Furthermore, from the perspective of more surely exerting the insulation property, the thickness of the first resin layer is more preferably more than 0.7 μm and less than 9.0 μm, more preferably more than 1.0 μm and less than 9.0 μm, more preferably more than 2.0 μm and less than 9.0 μm, more preferably more than 2.5 μm and less than 9.0 μm, and particularly preferably more than 3.0 μm and less than 9.0 μm. Furthermore, the upper limit of the thickness of the first resin layer may be 7.0 μm, 5.0 μm, or 3.0 μm. The first resin layer may be in a semi-cured state (B-Stage) or a fully cured state (C-Stage).

The minimum melt viscosity of the first resin layer has a small contribution to solving the problem of the present invention, so it is not particularly limited. However, from the viewpoint of improving the thickness reduction and insulation, the minimum melt viscosity is preferably 10,000 Pa･s or more, more preferably 100,000 Pa･s or more and 50,000,000 Pa･s or less, and particularly preferably 300,000 Pa･s or more and 50,000,000 Pa･s or less. In this specification, "minimum melt viscosity" means the viscosity that exhibits the lowest value among the viscosities measured using a rheometer (viscoelasticity measuring device) under the conditions of a starting temperature of 80°C, an end temperature of 180°C, a heating rate of 3°C/min, a frequency of 10 pts/s, and a strain of 0.1%. The minimum melt viscosity of the first resin layer can be adjusted to a desired value by appropriately selecting the type of thermosetting resin contained therein, controlling the curing degree of the resin, or adding an inorganic filler.

In order to further improve the manufacturability of the substrate with the insulating resin layer, the elongation of the first resin layer is preferably 1% or more and less than 50%, more preferably 1% or more and less than 40%, and even more preferably 2% or more and less than 30%. In this specification, "elongation" is calculated using the measurement method in accordance with JIS K7113-1.

The first resin layer of this embodiment can be formed by coating or other known means using a varnish which is a solution of a resin composition containing a thermosetting resin. The thermosetting resin is not particularly limited as long as the thickness reduction condition is satisfied, and the desired thermosetting resin can be used according to the preferred physical properties. In addition, the resin composition can also contain inorganic fillers and other additives as described below as needed.

(Thermosetting resin) As mentioned above, the thermosetting resin used in the first resin layer is not particularly limited, and examples thereof include polyimide, liquid crystal polyester, epoxy resin, cyanate compound, maleimide compound, phenolic resin, thermosetting modified polyphenylene ether resin, benzophenone compound, organic modified polysiloxane and a compound having a polymerizable unsaturated group. These thermosetting resins may be used alone or in combination of two or more.

From the viewpoint of more reliably reducing the thickness to less than 30%, the first resin layer of these thermosetting resins preferably contains at least one of polyimide and liquid crystal polyester. Furthermore, from the viewpoint of obtaining an insulating resin layer having a better peel strength, it is more preferable that the first resin layer contains at least one of epoxy resin and phenolic resin in addition to at least one of polyimide and liquid crystal polyester, and it is more preferable that the first resin layer contains at least one of dimaleimide compound in addition to these.

-Polyimide- As for polyimide, commercially available products can be appropriately selected and used. As for polyimide, for example, block copolymer polyimide can be used. As for such block copolymer polyimide, for example, block copolymer polyimide described in International Publication No. WO2010-073952 can be cited. More specifically, as a block copolymer polyimide, there can be exemplified a copolymer polyimide having a structure in which a structure A in which an imide oligomer composed of a second structural unit is bonded to a terminal of an imide oligomer composed of a first structural unit, and a structure B in which an imide oligomer composed of a first structural unit is bonded to a terminal of an imide oligomer composed of a second structural unit. Here, the second structural unit is different from the first structural unit.

These block copolymer polyimides can be synthesized by reacting tetracarboxylic dianhydride and diamine in a polar solvent to obtain an imide oligomer, and then adding tetracarboxylic dianhydride and other diamines, or adding other tetracarboxylic dianhydrides and diamines, and performing a sequential polymerization reaction of imidization. For example, the imide oligomer composed of the first structural unit is preferably an imide oligomer having a weight average molecular weight of about 5,000 or more and 30,000 or less. For example, tetracarboxylic dianhydride can be 3,4,3',4'-biphenyltetracarboxylic dianhydride. For example, diamine can be 1,3-bis(3-aminophenoxy)benzene and 2,2-bis[4-(4-aminophenoxy)phenyl]propane. These may be used alone or in combination of two or more.

As polar solvents, for example, N-methyl-2-pyrrolidone, dimethylacetamide, dimethylformamide, dimethylsulfoxide, cyclobutylsulfoxide, and tetramethylurea, polar solvents that dissolve polyimide, can be cited. In addition, ketone-based or ether-based solvents can also be used in combination. As ketone-based solvents, for example, methyl ethyl ketone, methyl propyl ketone, methyl isopropyl ketone, methyl butyl ketone, methyl isobutyl ketone, methyl n-hexyl ketone, diethyl ketone, diisopropyl ketone, diisobutyl ketone, cyclopentanone, cyclohexanone, methyl cyclohexanone, acetylacetone, diacetone alcohol, and cyclohexene-n-one can be cited. Examples of the ether solvent include dipropyl ether, diisopropyl ether, dibutyl ether, tetrahydrofuran, tetrahydropyran, ethyl isoamyl alcohol, ethyl tert-butyl ether, ethyl benzyl ether, diethylene glycol dimethyl ether, cresyl methyl ether, anisole, and phenethyl ether. These polar solvents may be used alone or in combination of two or more.

As for the method of removing the water generated during the imidization, it is preferable to add a solvent such as toluene and xylene that can azeotrope with water to the reaction system and remove the water to the outside of the system. In addition, in order to promote the reaction, an amine catalyst such as pyridine or a two-component catalyst of an alkali such as pyridine and a cyclic ester such as γ-valerolactone can be used. The reaction temperature of the imidization is preferably above 120°C and below 200°C. Solvents such as toluene and xylene that can azeotrope with water, and catalysts such as pyridine, will eventually be distilled out of the system, thereby obtaining a polar solvent solution containing only block copolymer polyimide.

As for the block copolymer polyimide, a block copolymer polyimide having a structural unit represented by the following formula (A) and a structural unit represented by the following formula (B) can be preferably used. Here, m and n in the formula can be positive numbers within the range of the desired weight average molecular weight described below.

[Chemistry 1]

The tetracarboxylic dianhydride used in the synthesis of the block copolymer polyimide is preferably 3,4,3',4'-biphenyltetracarboxylic dianhydride. The diamine used in the synthesis of the block copolymer polyimide is preferably 1,3-bis(3-aminophenoxy)benzene and 2,2-bis[4-(4-aminophenoxy)phenyl]propane. In addition, in order to control the molecular weight of the block of each structural unit, for example, the molar ratio of tetracarboxylic dianhydride to diamine can be shifted in a manner such that one becomes more, thereby leaving an acid anhydride skeleton or an amine skeleton at the end, and in the second stage of the reaction, the molar ratio of tetracarboxylic dianhydride to other diamines or the molar ratio of other tetracarboxylic dianhydride to diamines is shifted in a manner opposite to the reaction in the first stage. In this way, a block copolymer polyimide having a desired molecular weight can be obtained.

The weight average molecular weight (Mw) of the block copolymer polyimide is not particularly limited, but is preferably 50,000 or more and 300,000 or less, and more preferably 80,000 or more and 200,000 or less. If the weight average molecular weight is 50,000 or more, the first resin layer can be more effectively prevented from becoming brittle. If the weight average molecular weight is 300,000 or less, the coating difficulty caused by the increased solution viscosity can be more effectively prevented. In this specification, the weight average molecular weight is measured by GPC (gel permeation chromatography) using NMP as a solvent and converted to polystyrene.

In order to control the final molecular weight, the molar ratio of tetracarboxylic dianhydride to diamine may be shifted and synthesized in a manner such that one of them becomes more. When the block copolymer polyimide has the structural unit represented by the above formula (A) and the structural unit represented by the formula (B), the molar ratio of each structural unit is preferably (structural unit represented by the formula (A)): (structural unit represented by the formula (B)) = 1:9 to 3:1, and more preferably (structural unit represented by the formula (A)): (structural unit represented by the formula (B)) = 1:3 to 3:1. If the molar ratio of these structural units is within the above range, the decrease in adhesion and solder heat resistance can be more effectively suppressed.

As for the polyimide used in the present embodiment, for example, a solvent-soluble polyimide synthesized by the production method described in Japanese Patent Application Publication No. 2005-15629 may be used. Specifically, the solvent-soluble polyimide is obtained by polycondensing one or more selected from the group consisting of aliphatic tetracarboxylic dianhydride represented by the following formula (C) and aliphatic tetracarboxylic acid represented by the following formula (D) and derivatives of the aliphatic tetracarboxylic acid (hereinafter also collectively referred to as "aliphatic tetracarboxylic acids") and one or more diamines in a solvent in the presence of a tertiary amine.

[Chemistry 2] Here, in formula (C), R is a tetravalent aliphatic hydrocarbon group having 4 to 16 carbon atoms.

[Chemistry 3] Here, in formula (D), R is a tetravalent aliphatic hydrocarbon group having 4 to 16 carbon atoms, and Y ₁ to Y ₄ are each independently a hydrogen atom or a monovalent hydrocarbon group having 1 to 8 carbon atoms.

In the method for producing such a solvent-soluble polyimide, almost equal molar amounts of aliphatic tetracarboxylic acid and diamine are heated in a solvent and polycondensed in the presence of a tertiary amine. The molar ratio of the aliphatic tetracarboxylic acid to the diamine is preferably in the range of 95 mol% to 105 mol% relative to 100 mol% of either one.

In the production of general polyimide, it is common to use tetracarboxylic dianhydride as tetracarboxylic acid. However, in the above-mentioned method for producing solvent-soluble polyimide, in addition to aliphatic tetracarboxylic dianhydride, other aliphatic tetracarboxylic acids other than anhydrides, and derivatives such as esters of aliphatic tetracarboxylic acids and alcohols can also be used to produce practical polyimide. If aliphatic tetracarboxylic acids are used directly, it is advantageous in terms of production equipment and cost.

Examples of the aliphatic tetracarboxylic dianhydride represented by formula (C) include 1,2,3,4-cyclobutanetetracarboxylic dianhydride, 1,2,4,5-cyclopentanetetracarboxylic dianhydride, 1,2,4,5-cyclohexanetetracarboxylic dianhydride, and bicyclo[2.2.2]oct-7-ene-2,3,5,6-tetracarboxylic dianhydride. Examples of the aliphatic tetracarboxylic acid represented by formula (D) and its derivatives include 1,2,3,4-cyclobutanetetracarboxylic acid, 1,2,4,5-cyclopentanetetracarboxylic acid, 1,2,4,5-cyclohexanetetracarboxylic acid, and bicyclo[2.2.2]oct-7-ene-2,3,5,6-tetracarboxylic acid, and alcohol esters thereof. These may be used alone or in combination of two or more. Among them, 1,2,4,5-cyclohexanetetracarboxylic dianhydride and 1,2,4,5-cyclohexanetetracarboxylic acid are preferred.

In the method for producing the solvent-soluble polyimide, other tetracarboxylic acids and their derivatives may be mixed and used within the range that does not impair the solubility of the solvent. Examples of such tetracarboxylic acids and their derivatives include pyromellitic acid, 3,3',4,4'-biphenyltetracarboxylic acid, 2,3,3',4'-biphenyltetracarboxylic acid, 2,2-bis(3,4-dicarboxyphenyl)propane, 2,2-bis(2,3-dicarboxyphenyl)propane, 2,2-bis(3,4-dicarboxyphenyl)-1,1,1,3,3,3-hexafluoropropane, 2,2-bis(2,3-dicarboxyphenyl)-1,1,1,3,3,3-hexafluoropropane, bis(3,4-dicarboxyphenyl)sulfone, bis(3 ,4-dicarboxyphenyl) ether, bis(2,3-dicarboxyphenyl) ether, 3,3',4,4'-diphenyl ketone tetracarboxylic acid, 2,2',3,3'-diphenyl ketone tetracarboxylic acid, 4,4-(p-phenylenedioxy)diphthalic acid, 4,4-(m-phenylenedioxy)diphthalic acid, ethylene tetracarboxylic acid, 3-carboxymethyl-1,2,4-cyclopentanetricarboxylic acid, 1,1-bis(2,3-dicarboxyphenyl)ethane, bis(2,3-dicarboxyphenyl)methane, bis(3,4-dicarboxyphenyl)methane, and their derivatives. The proportion of these other tetracarboxylic acids and their derivatives in the reaction substrate is preferably less than 50 mol% relative to 100 mol% of all tetracarboxylic acids and their derivatives in the reaction substrate.

The diamine is preferably an aromatic diamine having 6 to 28 carbon atoms and an aliphatic diamine having 2 to 28 carbon atoms. Examples of the diamine include p-phenylenediamine, m-phenylenediamine, 4,4'-diaminobiphenyl, 4,4'-diamino-2,2'-dimethylbiphenyl, 4,4'-diamino-3,3'-dimethylbiphenyl, 4,4'-diamino-2,2'-bis(trifluoromethyl)biphenyl, 4,4'-diaminodiphenyl ether, 3,4'-diaminodiphenyl ether, 4,4'-diaminodiphenylmethane, 4,4'-diaminodiphenyl ketone, 4,4'-diaminodiphenyl sulfide, 4,4'-diaminodiphenyl sulfide, 1,4-bis(4-aminophenoxy)benzene, 1,3-bis(4-aminophenoxy)benzene, 4,4'-bis(4-aminophenoxy)biphenyl, bis[4- Aromatic diamines such as bis[4-(4-aminophenoxy)phenyl]sulfone, 2,2-bis[4-(4-aminophenoxy)phenyl]propane, 2,2-bis[4-(4-aminophenoxy)phenyl]-1,1,1,3,3,3-hexafluoropropane, bis[4-(3-aminophenoxy)phenyl]sulfone, and 9,9-bis(4-aminophenyl)fluorene ; aliphatic diamines such as ethylenediamine, hexamethylenediamine, polyethylene glycol bis(3-aminopropyl) ether, polypropylene glycol bis(3-aminopropyl) ether, 1,3-bis(aminomethyl)cyclohexane, 1,4-bis(aminomethyl)cyclohexane, 4,4'-diaminodicyclohexylmethane, 3(4),8(9)-bis(aminomethyl)-tricyclo[5.2.1.0 ^2,6 ]decane, m-phenylenediamine, p-phenylenediamine, isophoronediamine, and norbornenediamine; and siloxanediamines. These may be used alone or in combination of two or more. Among these diamines, the aromatic diamine is preferably 4,4'-diamino-3,3'-dimethylbiphenyl, 4,4'-diamino-2,2'-di(trifluoromethyl)biphenyl, 4,4'-diaminodiphenyl ether, 4,4'-diaminodiphenylmethane, 1,4-bis(4-aminophenoxy)benzene, 1,3-bis(4-aminophenoxy)benzene, 4,4'-bis(4-aminophenoxy)biphenyl, 2,2-bis[4-(4-aminophenoxy)phenyl]propane, and 2,2-bis[4-(4-aminophenoxy)phenyl]-1,1,1,3,3,3-hexafluoropropane. The aliphatic diamine is preferably 4,4'-diaminodicyclohexylmethane and 3(4),8(9)-bis(aminomethyl)-tricyclo[5.2.1.0 ^2,6 ]decane.

In the method for producing the solvent-soluble polyimide, the tertiary amine is preferably used in an amount of 0.001 mol or more and 1.0 mol or less, and more preferably 0.01 mol or more and 0.2 mol or less, per 1 mol of the aliphatic tetracarboxylic acid.

Examples of the tertiary amine include trimethylamine, triethylamine, tripropylamine, tributylamine, triethanolamine, N,N-dimethylethanolamine, N,N-diethylethanolamine, triethylenediamine, N-methylpyrrolidine, N-ethylpyrrolidine, N-methylpiperidine, N-ethylpiperidine, imidazole, pyridine, quinoline, and isoquinoline. Among these tertiary amines, triethylamine is particularly preferred.

As for the solvent used in the method for producing the solvent-soluble polyimide, for example, γ-butyrolactone, N,N-dimethylacetamide, N-methyl-2-pyrrolidone, N,N-dimethylformamide, dimethylsulfoxide, hexamethylphosphatamide, tetramethylenesulfoxide, p-chlorophenol, m-cresol, and 2-chloro-4-hydroxytoluene can be cited. These can be used alone or in combination of two or more. Among these, γ-butyrolactone, N,N-dimethylacetamide, and N-methyl-2-pyrrolidone are preferred, and γ-butyrolactone and N,N-dimethylacetamide are more preferred. In addition, a poor solvent for polyimide can be used in combination to the extent that the polymer does not precipitate. Examples of poor solvents include hexane, heptane, benzene, toluene, xylene, chlorobenzene, and o-dichlorobenzene. The total mass of the aliphatic tetracarboxylic acid and the diamine used in the solvent is preferably 1% by mass or more and 50% by mass or less, and more preferably 20% by mass or more and 45% by weight or less, relative to the total mass of the reaction solution.

The method of feeding the aliphatic tetracarboxylic acid and the diamine is not particularly limited, and examples thereof include a method of feeding both components at once, and a method of slowly feeding the other component in a solid or solution state into a solution containing one component (even if the other component is not completely dissolved). In particular, the method of feeding both components at once can shorten the feeding time, and is therefore advantageous in terms of productivity.

In order to fully exert the catalytic effect of the tertiary amine, it is preferred to feed it before the temperature is raised and the target temperature is reached. In particular, it is preferred to feed it simultaneously with the solvent, aliphatic tetracarboxylic acid, and diamine.

The method of feeding the solvent is not particularly limited, and examples thereof include: a method of feeding the solvent into the reaction tank in advance, a method of feeding the solvent into the reaction tank in which one or both of the aliphatic tetracarboxylic acid and the diamine are present, and a method of dissolving one of the aliphatic tetracarboxylic acid and the diamine in the solvent in advance and then feeding it into the reaction tank. These methods may be used alone or in combination of two or more. In addition, the solvent as described above may be added to the solvent-soluble polyimide solution in the middle of the reaction, in the state remaining in the reaction tank after the reaction, or in the state taken out of the reaction tank after the reaction, depending on the purpose.

In this embodiment, when the first resin layer contains polyimide, its content is not particularly limited. From the perspective of improving heat resistance and curing properties, it is preferably 10 parts by mass or more and 90 parts by mass or less, and more preferably 30 parts by mass or more and 80 parts by mass or less, relative to 100 parts by mass of the resin solid component in the first resin layer.

-Liquid crystal polyester- Liquid crystal polyester is an aromatic polyester that exhibits liquid crystal properties when melted. As for the liquid crystal polyester, a known one can be appropriately selected for use. As for the known liquid crystal polyester, for example, the aromatic polyester described in Japanese Patent Publication No. 2001-11296 can be cited. As for the liquid crystal polyester, specifically, an aromatic polyester containing 90 mol% or more of a structural unit represented by the following formula (E) (hereinafter referred to as "structural unit (E)") can be cited.

[Chemistry 4]

As for the aromatic polyester containing the above-mentioned structural unit (E), for example, from the viewpoint of easy acquisition, polyoxybenzoate which is actually a homopolymer of the structural unit (E) can be used. As for the method for producing the aromatic polyester, a known method can be adopted. In addition, the aromatic polyester containing the above-mentioned structural unit (E) is often difficult to dissolve or insoluble in ordinary solvents, or difficult to melt or infusible, and therefore does not show liquid crystal properties. Therefore, the aromatic polyester containing the above-mentioned structural unit (E) is preferably used in a powder state. The powder is obtained by pulverizing the resin or fiber of the aromatic polyester, and the average particle size can usually be greater than 0.1μm and less than 100μm, preferably greater than 0.5μm and less than 15μm.

The weight average molecular weight of the liquid crystal polyester is not particularly limited, but is usually 1,000 to 100,000, preferably 10,000 to 50,000.

As the liquid crystal polyester, a commercially available product may be appropriately selected and used. For example, "Econol E101-F" (trade name) manufactured by Sumitomo Chemical Industries, Ltd. may be used.

In this embodiment, when the first resin layer contains a liquid crystal polyester, its content is not particularly limited. From the viewpoint of improving heat resistance and curing properties, it is preferably 10 parts by mass or more and 90 parts by mass or less, and more preferably 30 parts by mass or more and 80 parts by mass or less, relative to 100 parts by mass of the resin solid component in the first resin layer.

-Epoxy resin- As for the epoxy resin, there is no particular limitation as long as it has two or more epoxy groups in one molecule, and any conventionally known epoxy resin can be used. From the perspective of improving adhesion and flexibility, the epoxy equivalent of the epoxy resin is preferably 250 g/eq or more and 850 g/eq or less, and more preferably 250 g/eq or more and 450 g/eq or less. The epoxy equivalent can be measured by conventional methods.

Examples of epoxy resins include polyoxynaphthalene epoxy resins, biphenyl aralkyl epoxy resins, naphthalene tetrafunctional epoxy resins, xylene epoxy resins, naphthol aralkyl epoxy resins, naphthalene aralkyl epoxy resins, bisphenol A epoxy resins, bisphenol F epoxy resins, bisphenol A novolac epoxy resins, trifunctional phenol epoxy resins, and tetrafunctional phenol epoxy resins. epoxy resins, naphthalene type epoxy resins, biphenyl type epoxy resins, aralkylphenol type epoxy resins, aliphatic epoxy resins, polyol type epoxy resins, epoxypropylamine type epoxy resins, epoxypropyl ester type epoxy resins, compounds obtained by epoxidizing the double bond of a diene compound such as butadiene, and compounds obtained by reacting a hydroxyl-containing polysiloxane with epichlorohydrin. Among them, the epoxy resin is preferably a polyoxynaphthalene type epoxy resin, a biphenyl aralkyl type epoxy resin, a naphthalene tetrafunctional type epoxy resin, a xylene type epoxy resin, a naphthol aralkyl type epoxy resin, or a naphthalene aralkyl type epoxy resin, especially in view of copper plating adhesion and flame retardancy. These epoxy resins may be used alone or in combination of two or more.

In this embodiment, when the first resin layer contains epoxy resin, its content is not particularly limited. From the viewpoint of improving heat resistance and curing properties, it is preferably 1 part by mass or more and 60 parts by mass or less, and more preferably 1 part by mass or more and 30 parts by mass or less, relative to 100 parts by mass of the resin solid component in the first resin layer.

-Cyanate Compound- Cyanate compounds have excellent properties such as chemical resistance and adhesion. With their excellent chemical resistance, they can form a uniform roughened surface. Therefore, cyanate compounds can be ideally used as a component of the resin layer in this embodiment.

Examples of cyanate compounds include: α-naphthol aralkyl cyanate compounds represented by the following formula (F), phenolic cyanate compounds represented by the following formula (G), biphenyl aralkyl cyanate compounds represented by the following formula (H), 1,3-dicyanobenzene, 1,4-dicyanobenzene, 1,3,5-tricyanobenzene, bis(3,5-dimethyl-4-cyanophenyl)methane, 1,3-dicyanonaphthalene, 1,4-dicyanonaphthalene, 1,6-dicyano 1,8-dicyanonaphthalene, 2,6-dicyanonaphthalene, 2,7-dicyanonaphthalene, 1,3,6-tricyanonaphthalene, 4,4'-dicyanobiphenyl, bis(4-cyanophenyl)methane, bis(4-cyanophenyl)propane, bis(4-cyanophenyl)ether, bis(4-cyanophenyl)sulfide, bis(4-cyanophenyl)sulfide, 2,2'-bis(4-cyanophenyl)propane, and bis(3,5-dimethyl-4-cyanophenyl)methane. These cyanate compounds may be used alone or in combination of two or more.

Among them, the α-naphthol aralkyl type cyanate ester compound represented by formula (F), the phenolic cyanate ester compound represented by formula (G), and the biphenyl aralkyl type cyanate ester compound represented by formula (H) are preferred because of their excellent flame retardancy, high curability, and low thermal expansion coefficient of the cured product.

[Chemistry 5] Here, in formula (F), ^R1 represents a hydrogen atom or a methyl group, and ⁿ¹ represents an integer greater than 1. Preferably, ⁿ¹ is an integer of 1 to 50.

[Chemistry 6]

In formula (G), ^R2 represents a hydrogen atom or a methyl group, and ⁿ² represents an integer greater than 1. ⁿ² is preferably an integer of 1 to 50.

[Chemistry 7]

In formula (H), R ³ represents a hydrogen atom or a methyl group, and n ³ represents an integer greater than 1. n ³ is preferably an integer of 1 to 50.

In this embodiment, when the first resin layer contains a cyanate compound, its content is not particularly limited. Considering the viewpoint of improving heat resistance and adhesion with copper foil, it is preferably 1 mass part or more and 60 mass parts or less, and more preferably 1 mass part or more and 30 mass parts or less, relative to 100 mass parts of the resin solid component in the first resin layer.

-Maleimide compound- Maleimide compounds can improve the moisture absorption and heat resistance of the insulating resin layer, and therefore can be preferably used as a component of the resin layer in this embodiment. The maleimide compound is not particularly limited as long as it has two or more maleimide groups in one molecule, and any conventionally known maleimide compound can be used.

Examples of maleimide compounds include bis(4-maleimidophenyl)methane, 2,2-bis[4-(4-maleimidophenoxy)phenyl]propane, bis(3,5-dimethyl-4-maleimidophenyl)methane, bis(3-ethyl-5-methyl-4-maleimidophenyl)methane, and bis(3,5-diethyl-4-maleimidophenyl)methane; and polyphenylmethane maleimide. In addition, the resin composition solution may be mixed in the form of a prepolymer of these maleimide compounds or a prepolymer of a maleimide compound and an amine compound. These maleimide compounds can be used alone or in combination of two or more.

Among them, from the viewpoint of improving heat resistance, a bismaleimide compound is preferred, and bis(3-ethyl-5-methyl-4-maleimidophenyl)methane is more preferred.

In this embodiment, when the first resin layer contains a maleimide compound, its content is not particularly limited. Considering the viewpoint of improving heat resistance and adhesion to copper foil, it is preferably 5 parts by mass or more and 75 parts by mass or less, and more preferably 5 parts by mass or more and 45 parts by mass or less, relative to 100 parts by mass of the resin solid component in the first resin layer.

-Phenolic resin- As for the phenolic resin, there is no particular limitation as long as it is a resin having two or more phenolic hydroxyl groups in one molecule, and any phenolic resin known in the past can be used. As for the phenolic resin, for example, there can be mentioned: phenol novolac resin, alkylphenol novolac resin, bisphenol A novolac resin, dicyclopentadiene type phenolic resin, phenolic epoxy (Xylok) type phenolic resin, terpene modified phenolic resin, polyvinylphenol, aralkyl type phenolic resin, biphenyl aralkyl type phenolic resin, and the like, which are compounds in which two or more hydrogen atoms bonded to an aromatic ring in one molecule are substituted with hydroxyl groups. These phenolic resins may be used alone or in combination of two or more.

-Thermosetting modified polyphenylene ether resin- Thermosetting modified polyphenylene ether resin is a resin obtained by mixing thermoplastic polyphenylene ether resin and epoxy resin, dissolving them in a solvent such as toluene, adding 2-ethyl-4-methylimidazole as a catalyst, and crosslinking. Thermosetting modified polyphenylene ether resin can be used alone or in combination of two or more.

-Benzothiophene compounds- As for benzothiophene compounds, there are no particular limitations as long as they have a thiophene ring as a basic skeleton. In addition, in this embodiment, benzothiophene compounds also include compounds having a polycyclic thiophene skeleton such as naphthiophene compounds. The benzothiophene compounds can be used alone or in combination of two or more.

-Organic modified polysiloxane- There is no particular limitation on the organic modified polysiloxane, and specific examples include di(methylamino) polydimethylsiloxane, di(ethylamino) polydimethylsiloxane, di(propylamino) polydimethylsiloxane, di(epoxypropyl) polydimethylsiloxane, and di(epoxybutyl) polydimethylsiloxane. These organic modified polysiloxanes can be used alone or in combination of two or more.

-Compounds with polymerizable unsaturated groups- Compounds with polymerizable unsaturated groups are not particularly limited as long as they are not the above-mentioned compounds, and examples thereof include: vinyl compounds such as ethylene, propylene, styrene, divinylbenzene, and divinylbiphenyl; (meth)acrylates of monovalent or polyvalent alcohols such as methyl (meth)acrylate, 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, polypropylene glycol di(meth)acrylate, trihydroxymethylpropane di(meth)acrylate, trihydroxymethylpropane tri(meth)acrylate, pentaerythritol tetra(meth)acrylate, and dipentaerythritol hexa(meth)acrylate; epoxy (meth)acrylates such as bisphenol A epoxy (meth)acrylate and bisphenol F epoxy (meth)acrylate; benzocyclobutene resins, etc. These compounds having a polymerizable unsaturated group may be used alone or in combination of two or more. The term "(meth)acrylate" is a concept that includes both methacrylate and acrylate.

[Second resin layer] In this embodiment, the second resin layer is a layer containing a resin that is usually fluid during the pressing process as described above, and the layer itself is also fluid during the pressing process. The second resin layer is usually a layer that fills one side of the surface that contacts the surface of the second resin layer, which forms a component of a laminate together with a substrate to which the resin layer is attached. For example, the above-mentioned component may be a (conductor layer) such as a circuit pattern provided on a substrate, and the conductor layer is equivalent to a convex portion in a concave-convex shape formed together with the substrate, and is filled in the second resin.

From the viewpoint of making the embedding property of the conductor layer good, the minimum melt viscosity of the second resin layer is preferably 100,000 Pa･s or less, more preferably 10 Pa･s or more and 80,000 Pa･s or less, and more preferably 30 Pa･s or more and 60,000 Pa･s or less. Furthermore, from the same viewpoint, the minimum melt viscosity of the second resin layer is preferably lower than the minimum melt viscosity of the first resin layer, more preferably 10,000 Pa･s or more lower than the minimum melt viscosity of the first resin layer, more preferably 20,000 Pa･s or more lower, and particularly preferably 40,000 Pa･s or more lower. Furthermore, the minimum melt viscosity of the second resin layer may be less than 50,000,000 Pa.s, less than 49,950,000 Pa.s, or less than 49,900,000 Pa.s. The minimum melt viscosity of the second resin layer may be adjusted to a desired value by appropriately selecting the type of thermosetting resin contained therein, controlling the curing degree of the resin, or adding an inorganic filler.

The thickness of the second resin layer is not particularly limited, but is preferably 1.0 μm or more, more preferably 2.0 μm or more, and more preferably 3.0 μm or more, from the viewpoint of making the conductor layer more well-filled and the insulation more improved. On the other hand, from the viewpoint of making the substrate thinner, the thickness of the second resin layer is preferably 25 μm or less, more preferably 20 μm or less, more preferably 15 μm or less, more preferably 10 μm or less, and particularly preferably 9.0 μm or less. From the viewpoint of further improving the filling and insulation properties of the conductive layer and making the substrate thinner, the thickness of the second resin layer is preferably not less than 2.0 μm and not more than 20 μm, more preferably not less than 3.0 μm and not more than 20 μm, further preferably not less than 4.0 μm and not more than 15 μm, particularly preferably not less than 5.0 μm and not more than 10 μm, and most preferably not less than 5.0 μm and not more than 9.0 μm.

From the perspective of making the substrate thinner, the total thickness of the first resin layer and the second resin layer is preferably 30 μm or less, more preferably 15 μm or less, more preferably 20 μm or less, still more preferably 15 μm or less, still more preferably 14 μm or less, particularly preferably less than 12 μm, and most preferably 10 μm or less. From the perspective of making the substrate thinner in this way to more effectively and reliably exert the effects of the present invention, the total thickness is preferably 3.0 μm or more, more preferably 5.0 μm or more, and still more preferably 6.0 μm or more. Taking the above viewpoints into consideration, the total thickness is preferably 3.0 μm to 30 μm, more preferably 3.0 μm to 20 μm, further preferably 5.0 μm to 20 μm, further preferably 5.0 μm to 15 μm, particularly preferably 5.0 μm to 14 μm, further preferably 5.0 μm to less than 12 μm, and extremely preferably 5.0 μm to 10 μm.

The second resin layer in this embodiment is preferably a varnish of a solution of a resin composition containing a thermosetting resin, and can be formed by known means such as coating. There is no particular limitation on the thermosetting resin, and a desired thermosetting resin can be used according to the ideal physical properties. In addition, the resin composition can also contain inorganic fillers and other additives as described below as needed.

(Thermosetting resin) As mentioned above, the thermosetting resin used in the second resin layer is not particularly limited, and examples thereof include epoxy resins, cyanate compounds, maleimide compounds, phenolic resins, thermosetting modified polyphenylene ether resins, benzophenone compounds, organic-modified polysiloxane compounds, and compounds having polymerizable unsaturated groups. For these thermosetting resins, the same ones as those used in the first resin layer exemplified above can be used. These thermosetting resins can be used alone or in combination of two or more.

Among these thermosetting resins, from the viewpoint of obtaining an insulating resin layer having a higher peel strength, the second resin layer preferably contains at least one of an epoxy resin and a phenolic resin, and more preferably contains both an epoxy resin and a phenolic resin. Also, from the same viewpoint, the second resin layer more preferably contains a dimaleimide compound.

In this embodiment, when the second resin layer contains epoxy resin, its content is not particularly limited. From the viewpoint of improving heat resistance and curing properties, it is preferably 10 parts by mass or more and 80 parts by mass or less, and more preferably 30 parts by mass or more and 70 parts by mass or less, relative to 100 parts by mass of the resin solid component in the second resin layer.

In this embodiment, when the second resin layer contains a cyanate compound, its content is not particularly limited. Considering the viewpoint of improving heat resistance and adhesion to copper foil, it is preferably 15 parts by mass or more and 85 parts by mass or less, and more preferably 25 parts by mass or more and 65 parts by mass or less, relative to 100 parts by mass of the resin solid component in the second resin layer.

In this embodiment, when the second resin layer contains a maleimide compound, its content is not particularly limited. Considering the viewpoint of improving heat resistance and adhesion to copper foil, it is preferably 5 parts by mass or more and 75 parts by mass or less, and more preferably 5 parts by mass or more and 45 parts by mass or less, relative to 100 parts by mass of the resin solid component in the second resin layer.

[Other components] The first and second resin layers in this embodiment may contain other components such as fillers as needed.

-Filling material- As for the filling material, spherical fillers are preferred from the viewpoints of low thermal expansion coefficient, formability, filling property and rigidity. The spherical filler is not particularly limited as long as it is a spherical filler used in the insulating layer of the printed wiring board.

As spherical fillers, for example, there can be mentioned: silicon dioxides such as magnesium hydroxide, magnesium oxide, natural silicon dioxide, fused silicon dioxide, amorphous silicon dioxide, and hollow silicon dioxide; molybdenum compounds such as molybdenum disulfide, molybdenum oxide, and zinc molybdate; aluminum oxide; aluminum nitride; glass; titanium oxide; and zirconium oxide. These spherical fillers can be used alone or in combination of two or more.

As for the spherical filler, from the viewpoint of low thermal expansion, spherical silica such as spherical fused silica is suitable. As for commercially available spherical fused silica, for example, SC2050-MB, SC2500-SQ, SC4500-SQ, SO-C2, and SO-C1 (all trade names) manufactured by Admatechs, and SFP-130MC (trade name) manufactured by Denki Kagaku Kogyo Co., Ltd. can be cited.

The average particle size of spherical fillers such as spherical silica is not particularly limited, and is preferably 0.01 μm or more and 5 μm or less, more preferably 0.05 μm or more and 3 μm or less, more preferably 0.1 μm or more and 2 μm or less, and particularly preferably 0.3 μm or more and 1.5 μm or less. The average particle size of spherical silica can be measured by laser diffraction and scattering method based on Mie scattering theory. Specifically, a laser diffraction and scattering particle size distribution measuring device can be used to prepare the particle size distribution of spherical silica on a volume basis, and the median particle size is made the average particle size for measurement. The measurement sample can ideally be one in which spherical silica is dispersed in water using ultrasound. As the laser diffraction scattering type particle size distribution measuring apparatus, for example, "LA-500" (trade name) manufactured by Horiba, Ltd. can be used.

In this embodiment, the content of the spherical filler is not particularly limited. From the viewpoint of improving moldability, it is preferably 50 parts by mass or more and 500 parts by mass or less, and more preferably 100 parts by mass or more and 400 parts by mass or less, relative to 100 parts by mass of the resin solid component in each resin layer.

Furthermore, the spherical filler of the present embodiment may be surface treated with a silane coupling agent, etc. As for the silane coupling agent, the silane coupling agent described below may be used.

-Other components- Each resin layer in this embodiment may contain a silane coupling agent as another component, for example, to improve the moisture absorption and heat resistance of the insulating resin layer of this embodiment. The silane coupling agent is not particularly limited as long as it is a silane coupling agent generally used for surface treatment of inorganic substances. Specific examples of the silane coupling agent include aminosilane-based silane coupling agents such as γ-aminopropyltriethoxysilane and N-β-(aminoethyl)-γ-aminopropyltrimethoxysilane, epoxysilane-based silane coupling agents such as γ-glycidoxypropyltrimethoxysilane, vinylsilane-based silane coupling agents such as γ-methacryloyloxypropyltrimethoxysilane, cationic silane-based silane coupling agents such as N-β-(N-vinylbenzylaminoethyl)-γ-aminopropyltrimethoxysilane hydrochloride, and phenylsilane-based silane coupling agents. These silane coupling agents may be used alone or in combination of two or more.

In this embodiment, the content of the silane coupling agent in each resin layer is not particularly limited. From the perspective of improving moisture absorption and heat resistance, it is preferably 0.05 to 5 parts by mass, more preferably 0.1 to 3 parts by mass, relative to 100 parts by mass of the spherical filler. When two or more silane coupling agents are used in combination, the total amount of the silane coupling agents is preferably within the above range.

Each resin layer in the present embodiment may also contain a wetting dispersant in order to improve the manufacturability of the resin layer in the present embodiment. The wetting dispersant is not particularly limited as long as it is a wetting dispersant generally used for coatings, etc. Specific examples of wetting dispersants include Disperbyk (registered trademark)-110, Disperbyk-111, Disperbyk-180, Disperbyk-161, BYK (registered trademark)-W996, BYK-W9010, and BYK-W903 manufactured by BYK Co., Ltd. These wetting dispersants may be used alone or in combination of two or more.

In this embodiment, the content of the wetting and dispersing agent in each resin layer is not particularly limited. From the perspective of improving the manufacturability of the resin layer in this embodiment, it is preferably 0.1 to 5 parts by mass, more preferably 0.5 to 3 parts by mass, relative to 100 parts by mass of the spherical filler. In addition, when two or more wetting and dispersing agents are used in combination, the total amount of the wetting and dispersing agents is preferably within the above range.

Each resin layer in the present embodiment may also contain a hardening accelerator for the purpose of adjusting the hardening speed. There is no particular limitation on the hardening accelerator, and for example, it may be one commonly used in hardening acceleration of epoxy resins or cyanate compounds. Specific examples of hardening accelerators include organic metal salts of metals containing copper, zinc, cobalt, nickel, and manganese, such as zinc octylate, cobalt cycloalkanoate, nickel octylate, and manganese octylate, imidazoles and their derivatives, such as 2-ethyl-4-methylimidazole, 1-benzyl-2-phenylimidazole, and 2,4,5-trimethylimidazole, and tertiary amines, such as triethylamine and tributylamine. These hardening accelerators may be used alone or in combination of two or more.

In this embodiment, the content of the hardening accelerator in each resin layer is not particularly limited. From the perspective of obtaining a higher glass transition temperature, it is preferably 0.001 mass parts or more and 5 mass parts or less, and more preferably 0.01 mass parts or more and 3 mass parts or less, relative to 100 mass parts of the resin solid component in each resin layer. In addition, when two or more hardening accelerators are used in combination, the total amount of the hardening accelerators is preferably within the above range.

The resin layer in this embodiment may also contain other various polymer compounds and/or flame retardant compounds, etc. There is no particular limitation on the polymer compounds and flame retardant compounds as long as they are generally used.

As for the polymer compound, it is other than the above-mentioned thermosetting resin, and various thermoplastic resins and their oligomers, elastomers, etc. can be listed. As for the polymer compound, specifically, it can be listed: polyimide, polyamide imide, polystyrene, polyolefin, styrene butadiene rubber (SBR), isoprene rubber (IR), butadiene rubber (BR), acrylonitrile butadiene rubber (NBR), polyurethane, polypropylene, (meth) acrylic acid oligomer, (meth) acrylic acid polymer and polysilicone resin. Considering the viewpoint of compatibility, as for the polymer compound, acrylonitrile butadiene rubber and styrene butadiene rubber are suitable.

As for the flame retardant compound, any flame retardant compound other than the above-mentioned filler may be used, for example: phosphorus-containing compounds (such as phosphate esters, melamine phosphate, and phosphorus-containing epoxy resins), nitrogen-containing compounds (such as melamine and benzoguanamine), thiocyanate-containing compounds, and polysilicone-based compounds. These polymer compounds and flame retardant compounds may be used alone or in combination of two or more.

The resin layer in this embodiment may contain various other additives depending on the purpose. Specific examples of additives include: UV absorbers, antioxidants, photopolymerization initiators, fluorescent whitening agents, photosensitizers, dyes, pigments, thickeners, lubricants, defoamers, dispersants, levelers, and glossing agents. These additives may be used alone or in combination of two or more.

(Resin composition) The first and second resin layers in this embodiment can be formed using various resin compositions. In addition to the above-mentioned thermosetting resin, each resin composition can be prepared by mixing other components such as fillers as needed. In addition, the resin composition can also be prepared in the form of a solution obtained by dissolving these components in an organic solvent as needed. Such a solution of a resin composition can be ideally used as a varnish when preparing the base material of the insulating resin layer of this embodiment described later. As for the organic solvent, there is no particular limitation as long as it can ideally dissolve or disperse each component and exert the effect of the resin layer in this embodiment. Specific examples of the organic solvent include alcohols (e.g., methanol, ethanol, and propanol), ketones (e.g., acetone, methyl ethyl ketone, and methyl isobutyl ketone), amides (e.g., dimethylacetamide and dimethylformamide), and aromatic hydrocarbons (e.g., toluene and xylene). These organic solvents may be used alone or in combination of two or more.

The content of the organic solvent in the solution of the resin composition is not particularly limited as long as it is appropriately determined in such a way that the viscosity of the solution is required to make the thickness of each resin layer within the desired range. For example, the content may be 20 parts by mass or more and 1000 parts by mass or less, 20 parts by mass or more and 500 parts by mass or less, or 30 parts by mass or more and 300 parts by mass or less, relative to 100 parts by mass of the resin composition solution.

The arithmetic mean roughness (Ra) of the surface of each resin layer in this embodiment is preferably 2.0 μm or less, more preferably 0.10 μm or more and 1.0 μm or less, and even more preferably 0.15 μm or more and 0.50 μm or less. By making the arithmetic mean roughness (Ra) within the above range, the bonding strength between the substrate such as copper foil and the first resin layer, or the bonding strength between the resin layers can be improved, and the peeling of the layers during long-term use can be more effectively prevented. The surface of the resin layer can be a surface in contact with the substrate and a surface in contact with a surface other than the substrate (such as other resin layers) according to the purpose, and the arithmetic mean roughness (Ra) of either surface is preferably within the above range. The arithmetic mean roughness of the resin layer surface can be measured using a commercially available shape measurement microscope (laser microscope, for example, "VK-X210" (trade name) manufactured by KEYENCE CORPORATION).

(Method for manufacturing a substrate with an insulating resin layer) The method for manufacturing a substrate with an insulating resin layer in this embodiment is not particularly limited as long as it has a step of laminating an insulating resin layer composed of the above-mentioned resin composition on a substrate such as copper foil. In the laminating step, for example, a solution (varnish) obtained by dissolving or dispersing the resin composition in an organic solvent is first applied to the surface of the substrate, and then dried under heating and/or reduced pressure to remove the organic solvent and solidify the resin composition to form a first resin layer. As mentioned above, the first resin layer can be not only in a semi-hardened state, but also in a completely hardened state. Afterwards, on the first resin layer, a solution (varnish) obtained by dissolving or dispersing other resin components in an organic solvent is applied to the surface of the substrate, and dried under heating and/or reduced pressure to remove the organic solvent and solidify the resin component to form a second resin layer. At this time, the second resin layer is preferably in a semi-hardened state (B-stage). In addition, a protective layer such as a plastic film may also be provided in the second resin layer. The protective layer is appropriately removed when the laminate is produced later. There is no particular limitation on drying conditions. The content ratio of the organic solvent to each resin layer is usually less than 10 parts by mass, preferably less than 5 parts by mass, relative to 100 parts by mass of each resin layer. The conditions for achieving drying depend on the amount of organic solvent in the varnish. For example, when the varnish contains 30 parts by mass and less than 60 parts by mass of organic solvent relative to 100 parts by mass of the varnish, it can be dried for about 3 to 10 minutes under heating conditions of 50°C to 160°C.

There is no particular limitation on the method for coating the resin composition on the substrate. For example, known coating methods such as rod coating, air knife coating, gravure coating, reverse gravure coating, micro-gravure coating, reverse micro-gravure coating, die coating, dip coating, spin coating, and spray coating can be used.

<Laminate of the present embodiment and its manufacturing method> The laminate of the substrate with the insulating resin layer of the present embodiment (hereinafter sometimes referred to as "laminate") can be used, for example, to make a coreless substrate to be provided on a printed wiring board or a substrate for mounting semiconductor components. The coreless substrate can also be a coreless substrate for stacking materials. The laminate of the present embodiment can be, for example, a laminate of a conductive layer and an insulating layer formed by the substrate with the insulating resin layer of the present embodiment, or can have a stacking layer. At least one of the above-mentioned conductive layer and insulating layer is a multilayer, and the laminate may be a laminate of conductive layers and insulating layers alternately laminated. Here, for example, when the insulating layer is formed by laminating the substrate with the insulating resin layer of the present embodiment, the substrate with the conductive layer formed may be laminated in a manner that the substrate is in contact with the second resin layer of the substrate with the insulating resin layer of the present embodiment using copper foil as the substrate, thereby forming the insulating layer. Furthermore, when three or more substrates with insulating resin layers are used to form an insulating layer, the substrate can be removed as needed, and each resin layer can be stacked to form an insulating layer. Furthermore, when the substrate in the substrate with insulating resin layer of this embodiment is copper foil, the copper foil can also play the role of a conductive layer, and other conductors (copper foil, etc.) such as copper foil of a copper-clad laminate can be stacked on the insulating layer to form a conductive layer.

When the stacked body of the present embodiment has a stacked layer, for example, the stacked layer has a plurality of conductive layers and insulating layers, and the conductive layers are arranged between the insulating layers and on the surface of the outermost layer of the stacked layer. In this case, the number of insulating layers is not particularly limited, and for example, it can be 3 layers or 4 layers. In addition, the stacked body of the present embodiment can also be used to manufacture a coreless substrate. As for the coreless substrate, for example, it can be a coreless substrate with more than 2 layers, and for example, it can also be a coreless substrate with 3 layers. The structure of the coreless substrate is described below.

In the laminate of this embodiment, considering the need for thin film, the thickness of at least one insulating layer is preferably 1 μm or more and less than 15 μm. The thickness of the insulating layer may vary according to the use of the laminate, for example, it is more preferably 1 μm or more and 14 μm or less, and more preferably 1 μm or more and 12 μm or less. In addition, considering the same point of view, the thickness of all insulating layers is preferably within the above numerical range.

In the laminate, the thickness of the layer derived from the first resin layer is not particularly limited, but is preferably less than 10 μm from the viewpoint of thinner film. From the viewpoint of more surely exerting the insulation property, the thickness of the layer is more preferably 1.0 μm or more and 9.0 μm or less, more preferably 2.0 μm or more and 9.0 μm or less, more preferably 2.5 μm or more and 9.0 μm or less, and particularly preferably 3.0 μm or more and 9.0 μm or less. The upper limit of the thickness of the layer may be 7.0 μm or 5.0 μm.

In the laminate, the thickness of the layer derived from the second resin layer is not particularly limited, but is preferably 2.0 μm or more, more preferably 3.0 μm or more, from the viewpoint of better embedding of the conductor layer and further improving insulation. On the other hand, from the viewpoint of making the substrate thinner, the thickness of the layer is preferably 20 μm or less, more preferably 15 μm or less, further preferably 10 μm or less, and particularly preferably 9.0 μm or less. From the perspective of further improving the filling and insulation properties of the conductive layer and making the substrate thinner, the thickness of the layer is preferably greater than 2.0 μm and less than 20 μm, further preferably greater than 3.0 μm and less than 20 μm, further preferably greater than 4.0 μm and less than 15 μm, particularly preferably greater than 5.0 μm and less than 10 μm, and most preferably greater than 5.0 μm and less than 9.0 μm.

[Printed wiring board] The laminated body of this embodiment can be used as a printed wiring board. Here, the printed wiring board can be obtained by using a laminated body obtained by using a substrate with an insulating resin layer of this embodiment as a stacking material for a metal foil laminated board formed by completely hardening an insulating resin layer called a core material. If the substrate with an insulating resin layer of this embodiment and the laminated body obtained therefrom are used, for example, a thin printed wiring board can be manufactured without using a thick supporting substrate (carrier substrate). In addition, the printed wiring board obtained using the substrate with an insulating resin layer of this embodiment has better adhesion between layers and productivity (yield).

The surface of the metal-clad laminate is formed with a conductive circuit by plating a conductive layer obtained by stripping the metal foil of a commonly used metal-clad laminate and/or the metal foil. The substrate of the metal-clad laminate is not particularly limited, and examples thereof include glass epoxy substrates, metal substrates, polyester substrates, polyimide substrates, BT resin substrates, and thermosetting polyphenylene ether substrates.

In this embodiment, "stacking" means that the insulating resin layer in the insulating resin layer-attached substrate of this embodiment is stacked on the metal foil and/or conductor layer on the surface of the metal foil-clad laminate.

Generally, when an insulating resin layer (resin composition layer) is laminated on a metal-clad laminate using an adhesive film or the like as a laminating material, the resulting printed wiring board has a cured insulating resin layer, i.e., an insulating layer, on one or both sides. A conductive layer is formed on the insulating layer, but the surface roughness of the insulating layer is low. Therefore, generally, the insulating layer is roughened by a roughening process including a desmearing process to form unevenness on the insulating layer, and then the conductive layer is formed by electroless plating and/or electrolytic plating.

However, if the substrate with the insulating resin layer of the present embodiment is laminated as a stacking material on a metal foil-clad laminate, the resulting printed wiring board will have a substrate such as copper foil on one or both sides. Therefore, when the substrate has conductivity such as copper foil, even without applying a plating treatment, a circuit pattern can be directly formed on the substrate, and a high-density fine wiring can be formed. In addition, when manufacturing a printed wiring board or a substrate for mounting semiconductor components, even if the substrate is etched and then subjected to a plating treatment, the adhesion between the insulating layer and the plating can still be improved because the substrate surface will be transferred to the insulating resin layer.

In the manufacture of printed wiring boards, in order to electrically connect each conductive layer, via holes and/or through holes need to be processed. When the hole processing is performed, a roughening treatment including desmearing is performed afterwards. When the surface of the printed wiring board is protected by a conductive layer such as copper foil that has excellent adhesion to the insulating layer, the surface roughness of the printed wiring board can be suppressed even if the roughening treatment is performed.

Hole processing is usually performed by mechanical drilling, CO2 laser, UV laser and YAG laser. When the surface of the printed wiring board is protected by a conductive layer such as copper foil, the energy of these drillings or lasers can be enhanced. Therefore, according to this embodiment, inorganic substances such as glass fibers exposed from the hole surface can be ideally removed during hole processing. In addition, the roughening treatment usually consists of a swelling step, a surface roughening and slag dissolving step, and a neutralization step.

In the swelling step, a swelling agent is used to swell the surface of the insulating layer. The swelling agent is not particularly limited as long as it can improve the wettability of the surface of the insulating layer and swell the surface of the insulating layer to a degree that can promote the subsequent surface roughening and oxidative decomposition in the slag dissolution step. Examples thereof include alkaline solutions and surfactant solutions.

In the surface roughening and slag dissolving, an oxidizing agent is used to roughen the surface of the insulating layer and dissolve the slag at the same time. As for the oxidizing agent, an alkaline permanganate solution can be cited, and as an ideal specific example, an aqueous potassium permanganate solution and an aqueous sodium permanganate solution can be cited. The oxidizing agent treatment is called wet deslagging. In addition to wet deslagging, it can also be appropriately combined with dry deslagging by plasma treatment or UV treatment, mechanical grinding by a polishing wheel, and other well-known roughening treatments such as sandblasting.

In the neutralization step, the oxidizing agent used in the previous step is neutralized by a reducing agent. As the reducing agent, for example, an amine reducing agent can be mentioned. As a preferred specific example, an acidic aqueous solution such as a hydroxylamine sulfate aqueous solution, an ethylenediaminetetraacetic acid aqueous solution, and a nitrilotriacetic acid aqueous solution can be mentioned.

In this embodiment, after the vias and/or through holes are provided, or after the vias and/or through holes are debonded, metal plating is preferably performed to electrically connect the conductive layers. In this embodiment, even if metal plating is performed, the surface of the conductive layer is transferred to the insulating layer, thereby improving the adhesion between the insulating layer and the metal plating.

There is no particular limitation on the method of metal plating treatment, and a method of metal plating treatment in the manufacture of a general multi-layer printed wiring board can be appropriately used. There is no particular limitation on the method of metal plating treatment and the type of chemical solution used for plating, and a method of metal plating treatment and chemical solution used in the manufacture of a general multi-layer printed wiring board can be appropriately used. The chemical solution used for metal plating treatment can also be a commercial product. There is no particular limitation on the metal plating treatment method, and examples thereof include: treatment with a degreasing solution, treatment with a soft etching solution, pickling, treatment with a pre-dip solution, treatment with a catalyst solution, treatment with an accelerator solution, treatment with a chemical copper solution, pickling, and immersion in a copper sulfate solution and current flow.

Furthermore, when using a substrate with an insulating resin layer in a semi-hardened state for stacking, a printed wiring board can be obtained by generally applying heat treatment to the semi-hardened insulating resin layer and completely hardening it. In this embodiment, another substrate with an insulating resin layer can also be stacked on the obtained printed wiring board.

There is no particular limitation on the lamination method by the stacking method, and a vacuum pressure laminator can be preferably used. In this case, the substrate with the insulating resin layer of this embodiment can be laminated with an elastic body such as rubber interposed between the metal foil laminate. There is no particular limitation on the lamination conditions as long as they are the conditions used for lamination of a normal printed wiring board, and for example, the lamination can be carried out at a temperature of 70°C to 140°C, a contact pressure of 1kgf/ ^cm2 to 11kgf/ ^cm2 , and a reduced pressure environment of 20hPa or less. After lamination, the laminated insulating resin layer can also be smoothed by hot pressing using a metal plate. Lamination and smoothing can be performed continuously using a commercially available vacuum pressurized laminator. After lamination or smoothing, the insulating resin layer can be completely hardened by heating it for thermal hardening. The thermal hardening conditions vary depending on the types of components contained in the resin composition, but generally the hardening temperature is above 100°C and below 300°C, the pressure is above 0.1kgf/ ^cm2 and ^below 100kgf/cm2 (about 9.8kPa and below 9.8MPa), and the hardening time is 30 seconds to 5 hours.

The method for forming a circuit pattern on the copper foil or conductor layer on one or both sides of the printed wiring board in this embodiment can be exemplified by a semi-additive method, a full-additive method, and a subtractive method, etc. Among them, the semi-additive method is preferred from the perspective of forming a fine wiring pattern.

As an example of a method for forming a circuit pattern using a semi-additive method, one can cite a method of selectively applying electrolytic plating (pattern plating) using a plating resist, then stripping the plating resist, and etching the entire surface appropriately to form a wiring pattern. In the formation of a circuit pattern using a semi-additive method, electroless plating and electrolytic plating can be combined. At this time, it is advisable to dry each after electroless plating and after electrolytic plating. There is no particular limitation on drying after electroless plating, for example, it is advisable to dry at a temperature above 80°C and below 180°C for 10 minutes to 120 minutes. Drying after electrolytic plating is not particularly limited, and is preferably performed at a temperature of 130° C. or higher and 220° C. or lower for 10 to 120 minutes. The plating is preferably copper plating.

The insulating layer formed by the substrate with the resin layer of this embodiment has excellent plating adhesion. Here, the "plating adhesion" can be evaluated by, for example, using a sample formed with a conductive layer (plated copper) with a thickness of 18μm, measuring the adhesion of the conductive layer three times in accordance with JIS C6481 (5.7. (peel strength)), and finding the average value. In addition, for samples that swell due to drying after electrolytic copper plating, the non-swelled part is used for evaluation. The "plating adhesion" is preferably 0.1kN/m or more, more preferably 0.2kN/m or more, and more preferably 0.3kN/m or more.

An example of a method of forming a circuit pattern using a subtractive method is a method of forming a circuit pattern by selectively removing a conductive layer using an etching resist. Specifically, for example, a circuit pattern can be formed as follows. A dry film resist (e.g., RD-1225 (trade name) manufactured by Hitachi Chemical) is laminated (laminated) on the entire surface of a copper foil at a temperature of 110±10°C and a pressure of 0.50±0.02MPa. Then, exposure and masking are performed along the circuit pattern. Thereafter, the dry film resist is developed using a 1% sodium carbonate aqueous solution, and finally the dry film resist is stripped using an amine-based resist stripping solution. In this way, a circuit pattern can be formed on the copper foil.

In this embodiment, an insulating layer and/or a conductive layer may be further stacked on the printed wiring board to obtain a multi-layer printed wiring board. The inner layer of the multi-layer printed wiring board may also have a circuit substrate. The insulating resin layer in the substrate with the insulating resin layer of this embodiment will constitute one of the insulating layer and the conductive layer of the multi-layer printed wiring board.

There is no particular limitation on the method of lamination, and the method generally used for lamination of a conventional printed wiring board can be used. As for the lamination method, for example: multi-stage pressing, multi-stage vacuum pressing, laminator, vacuum laminator, and autoclave forming machine can be cited. The temperature during lamination is not particularly limited, for example, it is above 100°C and below 300°C. The pressure during lamination is not particularly limited, for example, it is above 0.1kgf/ ^cm2 and ^below 100kgf/cm2 (about 9.8kPa and below 9.8MPa). The heating time during lamination is not particularly limited, for example, it is 30 seconds to 5 hours. In addition, the degree of hardening can be adjusted as needed, for example, by post-hardening in a temperature range of above 150°C and below 300°C.

[Substrate for mounting semiconductor elements] As described above, the laminate of the present embodiment can be used as a substrate for mounting semiconductor elements. The substrate for mounting semiconductor elements can be manufactured, for example, by laminating the substrate with the insulating resin layer of the present embodiment on a metal foil-clad laminate, and masking and patterning the surface or substrate such as copper foil on one side of the obtained laminate to form a circuit pattern. The masking and patterning can utilize the known masking and patterning methods implemented in the manufacture of printed wiring boards, and are not particularly limited. It is preferable to form the circuit pattern by the above-mentioned subtractive method. The circuit pattern can be formed on only one side of the laminate, or on both sides.

[Multi-layer coreless substrate (multi-layer printed wiring board)] The stacked body of this embodiment can be made into a coreless substrate. As an example of a coreless substrate, a multi-layer coreless substrate can be cited. A multi-layer coreless substrate, for example, comprises: a multi-layer insulating layer consisting of a first insulating layer and one or more second insulating layers stacked on one side of the first insulating layer; and a multi-layer conductive layer consisting of a first conductive layer arranged between each layer of the multi-layer insulating layer and a second conductive layer arranged on the surface of the outermost layer of the multi-layer insulating layer; and the first insulating layer and the aforementioned second insulating layer each have a cured insulating resin layer in a substrate with an insulating resin layer of the present embodiment. A specific example of a multi-layer coreless substrate is described using FIG2 . FIG2 is a schematic diagram showing an example of a multi-layer coreless substrate in the present embodiment. The multi-layer coreless substrate 100 shown in FIG2 includes a first insulating layer 111 and two second insulating layers 112 stacked on the first insulating layer 111 in a single-sided direction (the bottom direction in the figure), and the first insulating layer 111 and the two second insulating layers 112 are each formed using an insulating resin layer in the base material with an insulating resin layer of the present embodiment. Furthermore, the multi-layer coreless substrate 100 shown in FIG. 2 has a multi-layer conductive layer composed of a first conductive layer 113 disposed between each layer of the multi-layer insulating layer (insulating layers 111 and 112) and a second conductive layer 113 disposed on the outermost layer of the multi-layer insulating layer (insulating layers 111 and 112). [Example]

The present invention is described in more detail below using embodiments and comparative examples, but the present invention is not limited thereto.

[Example 1] 60 parts by mass of block copolymer polyimide (product name: YN-003N, manufactured by PI Technology Laboratory), 40 parts by mass of 2,2-bis-[4-(4-maleimidephenoxy)phenyl]propane (product name: BMI-80, manufactured by K.I. Chemical Industry Co., Ltd.), 60 parts by mass of spherical silica (product name: SO-C1, average particle size 0.3 μm, manufactured by Admatechs Co., Ltd.), and 0.2 parts by mass of a wetting dispersant (product name: BYK-W903, manufactured by BYK Co., Ltd.) were blended and mixed, and then diluted with N-methyl-2-pyrrolidone (hereinafter referred to as "NMP") to obtain varnish A which is a solution of a resin composition. The obtained varnish A was applied to the matte side of a 12 μm thick copper foil (product name: 3EC-M2S-VLP, manufactured by Mitsui Metal & Mining Co., Ltd.) using a coating bar to obtain a coating film. The coating film was then heat-dried at 180°C for 10 minutes to obtain a resin-coated copper foil having a first resin layer formed on the copper foil.

Then, 36 parts by weight of biphenyl aralkyl phenolic resin (product name: KAYAHARD GPH-103, hydroxyl equivalent: 231 g/eq., manufactured by Nippon Kayaku Co., Ltd.), 39 parts by weight of biphenyl aralkyl epoxy resin (product name: NC-3000-FH, manufactured by Nippon Kayaku Co., Ltd., epoxide equivalent: 320 g/eq.), 39 parts by weight of naphthalene aralkyl epoxy resin (product name: HP-9900, epoxide equivalent: 274 g/eq.) were blended and mixed. q., DIC Co., Ltd.) 7 parts by mass, bis(3-ethyl-5-methyl-4-maleimidophenyl)methane (product name: BMI-70, K.I. Chemical Co., Ltd.) 18 parts by mass, 2,4,5-triphenylimidazole (Tokyo Chemical Industry Co., Ltd.) 0.5 parts by mass, and then diluted with methyl ethyl ketone to obtain a varnish B which is a solution of a resin composition. The obtained varnish B is applied to the first resin layer side of the resin-attached copper foil obtained in the above method using a coating bar to obtain a coating film. Then, the coated film was dried by heating at 150°C for 10 minutes, thereby obtaining a substrate (resin sheet) having an insulating resin layer having a first resin layer and a second resin layer in order from the substrate side. The thickness of the first resin layer was 2.5 μm, and the thickness of the second resin layer was 5.4 μm.

[Example 2] 60 parts by mass of block copolymer polyimide (product name: YN-003N, manufactured by PI Technology Laboratory), 40 parts by mass of 2,2-bis-[4-(4-maleimide phenoxy)phenyl]propane (product name: BMI-80, manufactured by K.I. Chemical Industry Co., Ltd.), 60 parts by mass of spherical silica (product name: SO-C1, average particle size 0.3 μm, manufactured by Admatechs Co., Ltd.), and 0.2 parts by mass of a wetting dispersant (product name: BYK-W903, manufactured by BYK Co., Ltd.) were blended and mixed, and then diluted with NMP to obtain varnish A which was a solution of a resin composition. The obtained varnish A was applied to the matte side of a 12 μm thick copper foil (product name: 3EC-M2S-VLP, manufactured by Mitsui Metal & Mining Co., Ltd.) using a coating bar to obtain a coating film. The coating film was then heat-dried at 180°C for 10 minutes to obtain a resin-coated copper foil having a first resin layer formed on the copper foil.

Then, 36 parts by weight of biphenyl aralkyl phenolic resin (product name: KAYAHARD GPH-103, hydroxyl equivalent: 231 g/eq., manufactured by Nippon Kayaku Co., Ltd.), 39 parts by weight of biphenyl aralkyl epoxy resin (product name: NC-3000-FH, manufactured by Nippon Kayaku Co., Ltd., epoxide equivalent: 320 g/eq.), and 39 parts by weight of naphthalene aralkyl epoxy resin (product name: HP-9900, epoxide equivalent: 274 g/eq., manufactured by DIC (co., Ltd.) 7 parts by mass, bis(3-ethyl-5-methyl-4-maleimidophenyl)methane (product name: BMI-70, manufactured by K.I. Chemicals Co., Ltd.) 18 parts by mass, slurry silica (product name: SC2050-MB, average particle size 0.7 μm, manufactured by Admatechs Co., Ltd.) 300 parts by mass, styrene butadiene rubber (product name: JSR TR2003, JSR Co., Ltd.) 20 parts by mass, wetting dispersant 1 (product name: DISPERBYK-161, BYK Co., Ltd.) 1 part by mass, wetting dispersant 2 (product name: DISPERBYK-111, BYK Co., Ltd.) 2 parts by mass, silane coupling agent (product name: KBM-403, Shin-Etsu Chemical Co., Ltd.) 1 part by mass, 2,4,5-triphenylimidazole (Tokyo Chemical Industry Co., Ltd.) 0.5 part by mass, and then diluted with methyl ethyl ketone to obtain varnish B which is a solution of the resin composition. The obtained varnish B (resin composition) was applied to the first resin layer side of the resin-attached copper foil obtained in the above method using a coating bar to obtain a coating film. Then, the coating film was heated and dried at 150°C for 10 minutes to obtain a substrate (resin sheet) with an insulating resin layer having a first resin layer and a second resin layer in order from the substrate side. The thickness of the first resin layer was 2.5 μm, and the thickness of the second resin layer was 5.1 μm.

[Example 3] 60 parts by mass of block copolymer polyimide (product name: YN-003N, manufactured by PI Technology Laboratory), 40 parts by mass of 2,2-bis-[4-(4-maleimide phenoxy)phenyl]propane (product name: BMI-80, manufactured by K.I. Chemical Industry Co., Ltd.), 60 parts by mass of spherical silica (product name: SO-C1, average particle size 0.3 μm, manufactured by Admatechs Co., Ltd.), and 0.2 parts by mass of a wetting dispersant (product name: BYK-W903, manufactured by BYK Co., Ltd.) were blended and mixed, and then diluted with NMP to obtain varnish A which was a solution of a resin composition. The obtained varnish A was applied to the matte side of a 12 μm thick copper foil (product name: 3EC-M2S-VLP, manufactured by Mitsui Metal & Mining Co., Ltd.) using a coating bar to obtain a coating film. The coating film was then heat-dried at 180°C for 10 minutes to obtain a resin-coated copper foil having a first resin layer formed on the copper foil.

Then, 36 parts by weight of biphenyl aralkyl phenolic resin (product name: KAYAHARD GPH-103, hydroxyl equivalent: 231 g/eq., manufactured by Nippon Kayaku Co., Ltd.), 39 parts by weight of biphenyl aralkyl epoxy resin (product name: NC-3000-FH, manufactured by Nippon Kayaku Co., Ltd., epoxide equivalent: 320 g/eq.), and 39 parts by weight of naphthalene aralkyl epoxy resin (product name: HP-9900, epoxide equivalent: 274 g/eq., manufactured by DIC (co., Ltd.) 7 parts by mass, bis(3-ethyl-5-methyl-4-maleimidodiphenyl)methane (product name: BMI-70, manufactured by K.I. Chemicals Co., Ltd.) 18 parts by mass, slurry silica (product name: SC2050-MB, average particle size 0.7 μm, manufactured by Admatechs Co., Ltd.) 420 parts by mass, styrene butadiene rubber (product name: JSR TR2003, JSR Co., Ltd.) 20 parts by mass, wetting dispersant 1 (product name: DISPERBYK-161, BYK Co., Ltd.) 1 part by mass, wetting dispersant 2 (product name: DISPERBYK-111, BYK Co., Ltd.) 2 parts by mass, silane coupling agent (product name: KBM-403, Shin-Etsu Chemical Co., Ltd.) 1 part by mass, 2,4,5-triphenylimidazole (Tokyo Chemical Industry Co., Ltd.) 0.5 part by mass, and then diluted with methyl ethyl ketone to obtain varnish B which is a solution of the resin composition. The obtained varnish B was applied to the first resin layer side of the resin-attached copper foil obtained in the above method using a coating bar to obtain a coating film. Then, the coating film was heated and dried at 150°C for 10 minutes to obtain a substrate (resin sheet) with an insulating resin layer having a first resin layer and a second resin layer in order from the substrate side. The thickness of the first resin layer was 2.5 μm, and the thickness of the second resin layer was 4.7 μm.

[Example 4] 50 parts by mass of block copolymer polyimide (product name: YN-003N, manufactured by PI Technology Laboratory), 50 parts by mass of 2,2-bis-[4-(4-maleimide phenoxy)phenyl]propane (product name: BMI-80, manufactured by K.I. Chemical Industry Co., Ltd.), 60 parts by mass of spherical silica (product name: SO-C1, average particle size 0.3 μm, manufactured by Admatechs Co., Ltd.), and 0.2 parts by mass of a wetting dispersant (product name: BYK-W903, manufactured by BYK Co., Ltd.) were blended and mixed, and then diluted with NMP to obtain varnish A which was a solution of a resin composition. The obtained varnish A was applied to the matte side of a 12 μm thick copper foil (product name: 3EC-M2S-VLP, manufactured by Mitsui Metal & Mining Co., Ltd.) using a coating bar to obtain a coating film. The coating film was then heat-dried at 180°C for 10 minutes to obtain a resin-coated copper foil having a first resin layer formed on the copper foil.

Then, 36 parts by weight of biphenyl aralkyl phenolic resin (product name: KAYAHARD GPH-103, hydroxyl equivalent: 231 g/eq., manufactured by Nippon Kayaku Co., Ltd.), 39 parts by weight of biphenyl aralkyl epoxy resin (product name: NC-3000-FH, manufactured by Nippon Kayaku Co., Ltd., epoxide equivalent: 320 g/eq.), and 39 parts by weight of naphthalene aralkyl epoxy resin (product name: HP-9900, epoxide equivalent: 274 g/eq., manufactured by DIC (co., Ltd.) 7 parts by mass, bis(3-ethyl-5-methyl-4-maleimidophenyl)methane (product name: BMI-70, manufactured by K.I. Chemicals Co., Ltd.) 18 parts by mass, slurry silica (product name: SC2050-MB, average particle size 0.7 μm, manufactured by Admatechs Co., Ltd.) 300 parts by mass, styrene butadiene rubber (product name: JSR TR2003, JSR Co., Ltd.) 20 parts by mass, wetting dispersant 1 (product name: DISPERBYK-161, BYK Co., Ltd.) 1 part by mass, wetting dispersant 2 (product name: DISPERBYK-111, BYK Co., Ltd.) 2 parts by mass, silane coupling agent (product name: KBM-403, Shin-Etsu Chemical Co., Ltd.) 1 part by mass, 2,4,5-triphenylimidazole (Tokyo Chemical Industry Co., Ltd.) 0.5 part by mass, and then diluted with methyl ethyl ketone to obtain varnish B which is a solution of the resin composition. The obtained varnish B (resin composition) was applied to the first resin layer side of the resin-attached copper foil obtained in the above method using a coating bar to obtain a coating film. Then, the coating film was heated and dried at 150°C for 10 minutes to obtain a substrate (resin sheet) with an insulating resin layer having a first resin layer and a second resin layer in order from the substrate side. The thickness of the first resin layer was 2.5 μm, and the thickness of the second resin layer was 5.1 μm.

[Example 5] 60 parts by mass of block copolymer polyimide (product name: YN-003N, manufactured by PI Technology Laboratory), 40 parts by mass of 2,2-bis-[4-(4-maleimide phenoxy)phenyl]propane (product name: BMI-80, manufactured by K.I. Chemical Industry Co., Ltd.), 60 parts by mass of spherical silica (product name: SO-C1, average particle size 0.3 μm, manufactured by Admatechs Co., Ltd.), and 0.2 parts by mass of a wetting dispersant (product name: BYK-W903, manufactured by BYK Co., Ltd.) were blended and mixed, and then diluted with NMP to obtain varnish A which was a solution of a resin composition. The obtained varnish A was applied to the matte side of a 12 μm thick copper foil (product name: 3EC-M2S-VLP, manufactured by Mitsui Metal & Mining Co., Ltd.) using a coating bar to obtain a coating film. The coating film was then heat-dried at 180°C for 10 minutes to obtain a resin-coated copper foil having a first resin layer formed on the copper foil.

Then, 36 parts by weight of biphenyl aralkyl phenolic resin (product name: KAYAHARD GPH-103, hydroxyl equivalent: 231 g/eq., manufactured by Nippon Kayaku Co., Ltd.), 39 parts by weight of biphenyl aralkyl epoxy resin (product name: NC-3000-FH, manufactured by Nippon Kayaku Co., Ltd., epoxide equivalent: 320 g/eq.), and 39 parts by weight of naphthalene aralkyl epoxy resin (product name: HP-9900, epoxide equivalent: 274 g/eq.) were blended and mixed. q., DIC Co., Ltd.), 7 parts by mass of bis(3-ethyl-5-methyl-4-maleimidophenyl)methane (product name: BMI-70, K.I. Chemical Co., Ltd.), 18 parts by mass of 2,4,5-triphenylimidazole (Tokyo Chemical Industry Co., Ltd.), and 0.5 parts by mass of 2,4,5-triphenylimidazole were added, and then diluted with methyl ethyl ketone to obtain a varnish B which is a solution of a resin composition. The obtained varnish B was applied to the first resin layer side of the resin-attached copper foil obtained in the above method using a coating bar to obtain a coating film. Then, the coated film was dried by heating at 150°C for 10 minutes, thereby obtaining a substrate (resin sheet) having a first resin layer and a second resin layer with an insulating resin layer in order from the substrate side. The thickness of the first resin layer was 2.5 μm, and the thickness of the second resin layer was 8.9 μm.

[Example 6] 40 parts by mass of biphenyl aralkyl epoxy resin (product name: NC-3000-FH, manufactured by Nippon Kayaku Co., Ltd.), 60 parts by mass of 2,2-bis-[4-(4-maleimide phenoxy)phenyl]propane (product name: BMI-80, manufactured by K.I. Chemical Industry Co., Ltd.), 60 parts by mass of spherical silica (product name: SO-C1, average particle size 0.3 μm, manufactured by Admatechs Co., Ltd.), and a wetting dispersant (product name: BYK-W903, BYK Co., Ltd.) was added in an amount of 0.2 parts by mass, and then diluted with NMP to obtain a varnish A which was a solution of a resin composition. The obtained varnish A was applied to the matte side of a 12 μm thick copper foil (product name: 3EC-M2S-VLP, Mitsui Metal & Mining Co., Ltd.) using a coating bar to obtain a coating film. Then, the coating film was heated and dried at 200°C for 10 minutes to obtain a resin-coated copper foil having a first resin layer formed on the copper foil.

Then, 36 parts by weight of biphenyl aralkyl phenolic resin (product name: KAYAHARD GPH-103, hydroxyl equivalent: 231 g/eq., manufactured by Nippon Kayaku Co., Ltd.), 39 parts by weight of biphenyl aralkyl epoxy resin (product name: NC-3000-FH, manufactured by Nippon Kayaku Co., Ltd., epoxide equivalent: 320 g/eq.), and 39 parts by weight of naphthalene aralkyl epoxy resin (product name: HP-9900, epoxide equivalent: 274 g/eq.) were blended and mixed. q., DIC Co., Ltd.), 7 parts by mass of bis(3-ethyl-5-methyl-4-maleimidophenyl)methane (product name: BMI-70, K.I. Chemical Co., Ltd.), 18 parts by mass of 2,4,5-triphenylimidazole (Tokyo Chemical Industry Co., Ltd.), and 0.5 parts by mass of 2,4,5-triphenylimidazole were added, and then diluted with methyl ethyl ketone to obtain a varnish B which is a solution of a resin composition. The obtained varnish B was applied to the first resin layer side of the resin-attached copper foil obtained in the above method using a coating bar to obtain a coating film. Then, the coated film was dried by heating at 150°C for 10 minutes, thereby obtaining a substrate (resin sheet) having an insulating resin layer having a first resin layer and a second resin layer in order from the substrate side. The thickness of the first resin layer was 2.7 μm, and the thickness of the second resin layer was 5.4 μm.

[Example 7] 60 parts by mass of block copolymer polyimide (product name: YN-003N, manufactured by PI Technology Laboratory), 40 parts by mass of 2,2-bis-[4-(4-maleimide phenoxy)phenyl]propane (product name: BMI-80, manufactured by K.I. Chemical Industry Co., Ltd.), 60 parts by mass of spherical silica (product name: SO-C1, average particle size 0.3 μm, manufactured by Admatechs Co., Ltd.), and 0.2 parts by mass of a wetting dispersant (product name: BYK-W903, manufactured by BYK Co., Ltd.) were blended and mixed, and then diluted with NMP to obtain varnish A which was a solution of a resin composition. The obtained varnish A was applied to the matte side of a 12 μm thick copper foil (product name: 3EC-M2S-VLP, manufactured by Mitsui Metal & Mining Co., Ltd.) using a coating bar to obtain a coating film. The coating film was then heat-dried at 180°C for 10 minutes to obtain a resin-coated copper foil having a first resin layer formed on the copper foil.

Then, 36 parts by weight of biphenyl aralkyl phenolic resin (product name: KAYAHARD GPH-103, hydroxyl equivalent: 231 g/eq., manufactured by Nippon Kayaku Co., Ltd.), 39 parts by weight of biphenyl aralkyl epoxy resin (product name: NC-3000-FH, manufactured by Nippon Kayaku Co., Ltd., epoxide equivalent: 320 g/eq.), and 39 parts by weight of naphthalene aralkyl epoxy resin (product name: HP-9900, epoxide equivalent: 274 g/eq., manufactured by DIC (co., Ltd.) 7 parts by mass, bis(3-ethyl-5-methyl-4-maleimidophenyl)methane (product name: BMI-70, manufactured by K.I. Chemicals Co., Ltd.) 18 parts by mass, slurry silica (product name: SC2050-MB, average particle size 0.7 μm, manufactured by Admatechs Co., Ltd.) 350 parts by mass, styrene butadiene rubber (product name: JSR TR2003, JSR Co., Ltd.) 20 parts by mass, wetting dispersant 1 (product name: DISPERBYK-161, BYK Co., Ltd.) 1 part by mass, wetting dispersant 2 (product name: DISPERBYK-111, BYK Co., Ltd.) 2 parts by mass, silane coupling agent (product name: KBM-403, Shin-Etsu Chemical Co., Ltd.) 1 part by mass, 2,4,5-triphenylimidazole (Tokyo Chemical Industry Co., Ltd.) 0.5 part by mass, and then diluted with methyl ethyl ketone to obtain varnish B which is a solution of the resin composition. The obtained varnish B (resin composition) was applied to the first resin layer side of the resin-attached copper foil obtained in the above method using a coating bar to obtain a coating film. Then, the coating film was heated and dried at 150°C for 10 minutes to obtain a substrate (resin sheet) with an insulating resin layer having a first resin layer and a second resin layer in order from the substrate side. The thickness of the first resin layer was 2.5 μm, and the thickness of the second resin layer was 4.8 μm.

[Example 8] 60 parts by mass of block copolymer polyimide (product name: YN-003N, manufactured by PI Technology Laboratory), 40 parts by mass of 2,2-bis-[4-(4-maleimide phenoxy)phenyl]propane (product name: BMI-80, manufactured by K.I. Chemical Industry Co., Ltd.), 30 parts by mass of spherical silica (product name: SO-C1, average particle size 0.3 μm, manufactured by Admatechs Co., Ltd.), and 0.2 parts by mass of a wetting dispersant (product name: BYK-W903, manufactured by BYK Co., Ltd.) were blended and mixed, and then diluted with NMP to obtain varnish A which was a solution of a resin composition. The obtained varnish A was applied to the matte side of a 12 μm thick copper foil (product name: 3EC-M2S-VLP, manufactured by Mitsui Metal & Mining Co., Ltd.) using a coating bar to obtain a coating film. The coating film was then heat-dried at 180°C for 10 minutes to obtain a resin-coated copper foil having a first resin layer formed on the copper foil.

Then, 36 parts by weight of biphenyl aralkyl phenolic resin (product name: KAYAHARD GPH-103, hydroxyl equivalent: 231 g/eq., manufactured by Nippon Kayaku Co., Ltd.), 39 parts by weight of biphenyl aralkyl epoxy resin (product name: NC-3000-FH, manufactured by Nippon Kayaku Co., Ltd., epoxide equivalent: 320 g/eq.), and 39 parts by weight of naphthalene aralkyl epoxy resin (product name: HP-9900, epoxide equivalent: 274 g/eq., manufactured by DIC (co., Ltd.) 7 parts by mass, bis(3-ethyl-5-methyl-4-maleimidophenyl)methane (product name: BMI-70, manufactured by K.I. Chemicals Co., Ltd.) 18 parts by mass, slurry silica (product name: SC2050-MB, average particle size 0.7 μm, manufactured by Admatechs Co., Ltd.) 350 parts by mass, styrene butadiene rubber (product name: JSR TR2003, JSR Co., Ltd.) 20 parts by mass, wetting dispersant 1 (product name: DISPERBYK-161, BYK Co., Ltd.) 1 part by mass, wetting dispersant 2 (product name: DISPERBYK-111, BYK Co., Ltd.) 2 parts by mass, silane coupling agent (product name: KBM-403, Shin-Etsu Chemical Co., Ltd.) 1 part by mass, 2,4,5-triphenylimidazole (Tokyo Chemical Industry Co., Ltd.) 0.5 part by mass, and then diluted with methyl ethyl ketone to obtain varnish B which is a solution of the resin composition. The obtained varnish B (resin composition) was applied to the first resin layer side of the resin-attached copper foil obtained in the above method using a coating rod to obtain a coating film. Then, the coating film was heated and dried at 150°C for 10 minutes to obtain a substrate (resin sheet) with an insulating resin layer having the first resin layer and the second resin layer in order from the substrate side. The thickness of the first resin layer was 1.8μm, and the thickness of the second resin layer was 3.2μm. [Example 9] 60 parts by mass of block copolymer polyimide (product name: YN-003N, manufactured by PI Technology Laboratory), 40 parts by mass of 2,2-bis-[4-(4-maleimide phenoxy)phenyl]propane (product name: BMI-80, manufactured by K.I. Chemical Industry Co., Ltd.), 30 parts by mass of spherical silica (product name: SO-C1, average particle size 0.3 μm, manufactured by Admatechs Co., Ltd.), and 0.2 parts by mass of a wetting dispersant (product name: BYK-W903, manufactured by BYK Co., Ltd.) were blended and mixed, and then diluted with NMP to obtain varnish A which was a solution of a resin composition. The obtained varnish A was applied to the matte side of a 12 μm thick copper foil (product name: 3EC-M2S-VLP, manufactured by Mitsui Metal & Mining Co., Ltd.) using a coating bar to obtain a coating film. The coating film was then heat-dried at 180°C for 10 minutes to obtain a resin-coated copper foil having a first resin layer formed on the copper foil.

Then, 36 parts by weight of biphenyl aralkyl phenolic resin (product name: KAYAHARD GPH-103, hydroxyl equivalent: 231 g/eq., manufactured by Nippon Kayaku Co., Ltd.), 39 parts by weight of biphenyl aralkyl epoxy resin (product name: NC-3000-FH, manufactured by Nippon Kayaku Co., Ltd., epoxide equivalent: 320 g/eq.), and 39 parts by weight of naphthalene aralkyl epoxy resin (product name: HP-9900, epoxide equivalent: 274 g/eq., manufactured by DIC (co., Ltd.) 7 parts by mass, bis(3-ethyl-5-methyl-4-maleimidophenyl)methane (product name: BMI-70, manufactured by K.I. Chemicals Co., Ltd.) 18 parts by mass, slurry silica (product name: SC2050-MB, average particle size 0.7 μm, manufactured by Admatechs Co., Ltd.) 350 parts by mass, styrene butadiene rubber (product name: JSR TR2003, JSR Co., Ltd.) 20 parts by mass, wetting dispersant 1 (product name: DISPERBYK-161, BYK Co., Ltd.) 1 part by mass, wetting dispersant 2 (product name: DISPERBYK-111, BYK Co., Ltd.) 2 parts by mass, silane coupling agent (product name: KBM-403, Shin-Etsu Chemical Co., Ltd.) 1 part by mass, 2,4,5-triphenylimidazole (Tokyo Chemical Industry Co., Ltd.) 0.5 part by mass, and then diluted with methyl ethyl ketone to obtain varnish B which is a solution of the resin composition. The obtained varnish B (resin composition) was applied to the first resin layer side of the resin-attached copper foil obtained in the above method using a coating bar to obtain a coating film. Then, the coating film was heated and dried at 150°C for 10 minutes to obtain a substrate (resin sheet) with an insulating resin layer having a first resin layer and a second resin layer in order from the substrate side. The thickness of the first resin layer was 1.8 μm, and the thickness of the second resin layer was 1.6 μm.

[Example 10] 60 parts by mass of block copolymer polyimide (product name: YN-003N, manufactured by PI Technology Laboratory), 40 parts by mass of 2,2-bis-[4-(4-maleimidephenoxy)phenyl]propane (product name: BMI-80, manufactured by K.I. Chemical Industry Co., Ltd.), 60 parts by mass of spherical silica (product name: SO-C1, average particle size 0.3 μm, manufactured by Admatechs Co., Ltd.), and 0.2 parts by mass of a wetting dispersant (product name: BYK-W903, manufactured by BYK Co., Ltd.) were blended and mixed, and then diluted with NMP to obtain varnish A which was a solution of a resin composition. The obtained varnish A was applied to the matte side of a 12 μm thick copper foil (product name: 3EC-M2S-VLP, manufactured by Mitsui Metal & Mining Co., Ltd.) using a coating bar to obtain a coating film. The coating film was then heat-dried at 180°C for 10 minutes to obtain a resin-coated copper foil having a first resin layer formed on the copper foil.

Then, 36 parts by weight of biphenyl aralkyl phenolic resin (product name: KAYAHARD GPH-103, hydroxyl equivalent: 231 g/eq., manufactured by Nippon Kayaku Co., Ltd.), 39 parts by weight of biphenyl aralkyl epoxy resin (product name: NC-3000-FH, manufactured by Nippon Kayaku Co., Ltd., epoxide equivalent: 320 g/eq.), and 39 parts by weight of naphthalene aralkyl epoxy resin (product name: HP-9900, epoxide equivalent: 274 g/eq.) were blended and mixed. q., DIC Co., Ltd.), 7 parts by mass of bis(3-ethyl-5-methyl-4-maleimidophenyl)methane (product name: BMI-70, K.I. Chemical Co., Ltd.), 18 parts by mass of 2,4,5-triphenylimidazole (Tokyo Chemical Industry Co., Ltd.), and 0.5 parts by mass of 2,4,5-triphenylimidazole were added, and then diluted with methyl ethyl ketone to obtain a varnish B which is a solution of a resin composition. The obtained varnish B was applied to the first resin layer side of the resin-attached copper foil obtained in the above method using a coating bar to obtain a coating film. Then, the coated film was dried by heating at 150°C for 10 minutes, thereby obtaining a substrate (resin sheet) having an insulating resin layer having a first resin layer and a second resin layer in order from the substrate side. The thickness of the first resin layer was 2.5 μm, and the thickness of the second resin layer was 23.2 μm.

[Example 11] 60 parts by mass of block copolymer polyimide (product name: YN-003N, manufactured by PI Technology Laboratory), 40 parts by mass of 2,2-bis-[4-(4-maleimide phenoxy)phenyl]propane (product name: BMI-80, manufactured by K.I. Chemical Industry Co., Ltd.), 60 parts by mass of spherical silica (product name: SO-C1, average particle size 0.3 μm, manufactured by Admatechs Co., Ltd.), and 0.2 parts by mass of a wetting dispersant (product name: BYK-W903, manufactured by BYK Co., Ltd.) were blended and mixed, and then diluted with NMP to obtain varnish A which was a solution of a resin composition. The obtained varnish A was applied to the matte side of a 12 μm thick copper foil (product name: 3EC-M2S-VLP, manufactured by Mitsui Metal & Mining Co., Ltd.) using a coating bar to obtain a coating film. The coating film was then heat-dried at 180°C for 10 minutes to obtain a resin-coated copper foil having a first resin layer formed on the copper foil.

Then, 36 parts by weight of biphenyl aralkyl phenolic resin (product name: KAYAHARD GPH-103, hydroxyl equivalent: 231 g/eq., manufactured by Nippon Kayaku Co., Ltd.), 39 parts by weight of biphenyl aralkyl epoxy resin (product name: NC-3000-FH, manufactured by Nippon Kayaku Co., Ltd., epoxide equivalent: 320 g/eq.), and 39 parts by weight of naphthalene aralkyl epoxy resin (product name: HP-9900, epoxide equivalent: 274 g/eq.) were blended and mixed. q., DIC Co., Ltd.), 7 parts by mass of bis(3-ethyl-5-methyl-4-maleimidophenyl)methane (product name: BMI-70, K.I. Chemical Co., Ltd.), 18 parts by mass of 2,4,5-triphenylimidazole (Tokyo Chemical Industry Co., Ltd.), and 0.5 parts by mass of 2,4,5-triphenylimidazole were added, and then diluted with methyl ethyl ketone to obtain a varnish B which is a solution of a resin composition. The obtained varnish B was applied to the first resin layer side of the resin-attached copper foil obtained in the above method using a coating bar to obtain a coating film. Then, the coated film was dried by heating at 150°C for 10 minutes, thereby obtaining a substrate (resin sheet) having an insulating resin layer having a first resin layer and a second resin layer in order from the substrate side. The thickness of the first resin layer was 2.5 μm, and the thickness of the second resin layer was 17.9 μm.

[Example 12] 60 parts by mass of block copolymer polyimide (product name: YN-003N, manufactured by PI Technology Laboratory), 40 parts by mass of 2,2-bis-[4-(4-maleimide phenoxy)phenyl]propane (product name: BMI-80, manufactured by K.I. Chemical Industry Co., Ltd.), 60 parts by mass of spherical silica (product name: SO-C1, average particle size 0.3 μm, manufactured by Admatechs Co., Ltd.), and 0.2 parts by mass of a wetting dispersant (product name: BYK-W903, manufactured by BYK Co., Ltd.) were blended and mixed, and then diluted with NMP to obtain varnish A which was a solution of a resin composition. The obtained varnish A was applied to the matte side of a 12 μm thick copper foil (product name: 3EC-M2S-VLP, manufactured by Mitsui Metal & Mining Co., Ltd.) using a coating bar to obtain a coating film. The coating film was then heat-dried at 180°C for 10 minutes to obtain a resin-coated copper foil having a first resin layer formed on the copper foil.

Then, 36 parts by weight of biphenyl aralkyl phenolic resin (product name: KAYAHARD GPH-103, hydroxyl equivalent: 231 g/eq., manufactured by Nippon Kayaku Co., Ltd.), 39 parts by weight of biphenyl aralkyl epoxy resin (product name: NC-3000-FH, manufactured by Nippon Kayaku Co., Ltd., epoxide equivalent: 320 g/eq.), and 39 parts by weight of naphthalene aralkyl epoxy resin (product name: HP-9900, epoxide equivalent: 274 g/eq.) were blended and mixed. q., DIC Co., Ltd.), 7 parts by mass of bis(3-ethyl-5-methyl-4-maleimidophenyl)methane (product name: BMI-70, K.I. Chemical Co., Ltd.), 18 parts by mass of 2,4,5-triphenylimidazole (Tokyo Chemical Industry Co., Ltd.), and 0.5 parts by mass of 2,4,5-triphenylimidazole were added, and then diluted with methyl ethyl ketone to obtain a varnish B which is a solution of a resin composition. The obtained varnish B was applied to the first resin layer side of the resin-attached copper foil obtained in the above method using a coating bar to obtain a coating film. Then, the coated film was dried by heating at 150°C for 10 minutes, thereby obtaining a substrate (resin sheet) having an insulating resin layer having a first resin layer and a second resin layer in order from the substrate side. The thickness of the first resin layer was 2.5 μm, and the thickness of the second resin layer was 14.3 μm.

[Example 13] 60 parts by mass of block copolymer polyimide (product name: YN-003N, manufactured by PI Technology Laboratory), 40 parts by mass of 2,2-bis-[4-(4-maleimide phenoxy)phenyl]propane (product name: BMI-80, manufactured by K.I. Chemical Industry Co., Ltd.), 60 parts by mass of spherical silica (product name: SO-C1, average particle size 0.3 μm, manufactured by Admatechs Co., Ltd.), and 0.2 parts by mass of a wetting dispersant (product name: BYK-W903, manufactured by BYK Co., Ltd.) were blended and mixed, and then diluted with NMP to obtain varnish A which was a solution of a resin composition. The obtained varnish A was applied to the matte side of a 12 μm thick copper foil (product name: 3EC-M2S-VLP, manufactured by Mitsui Metal & Mining Co., Ltd.) using a coating bar to obtain a coating film. The coating film was then heat-dried at 180°C for 10 minutes to obtain a resin-coated copper foil having a first resin layer formed on the copper foil.

Then, 36 parts by weight of biphenyl aralkyl phenolic resin (product name: KAYAHARD GPH-103, hydroxyl equivalent: 231 g/eq., manufactured by Nippon Kayaku Co., Ltd.), 39 parts by weight of biphenyl aralkyl epoxy resin (product name: NC-3000-FH, manufactured by Nippon Kayaku Co., Ltd., epoxide equivalent: 320 g/eq.), and 39 parts by weight of naphthalene aralkyl epoxy resin (product name: HP-9900, epoxide equivalent: 274 g/eq.) were blended and mixed. q., DIC Co., Ltd.), 7 parts by mass of bis(3-ethyl-5-methyl-4-maleimidophenyl)methane (product name: BMI-70, K.I. Chemical Co., Ltd.), 18 parts by mass of 2,4,5-triphenylimidazole (Tokyo Chemical Industry Co., Ltd.), and 0.5 parts by mass of 2,4,5-triphenylimidazole were added, and then diluted with methyl ethyl ketone to obtain a varnish B which is a solution of a resin composition. The obtained varnish B was applied to the first resin layer side of the resin-attached copper foil obtained in the above method using a coating bar to obtain a coating film. Then, the coated film was dried by heating at 150°C for 10 minutes, thereby obtaining a substrate (resin sheet) having an insulating resin layer having a first resin layer and a second resin layer in order from the substrate side. The thickness of the first resin layer was 2.5 μm, and the thickness of the second resin layer was 4.5 μm.

[Comparative Example 1] 36 parts by mass of biphenyl aralkyl phenolic resin (product name: KAYAHARD GPH-103, hydroxyl equivalent: 231 g/eq., manufactured by Nippon Kayaku Co., Ltd.), 39 parts by mass of biphenyl aralkyl epoxy resin (product name: NC-3000-FH, manufactured by Nippon Kayaku Co., Ltd., epoxy equivalent: 320 g/eq.), 39 parts by mass of naphthalene aralkyl epoxy resin (product name: HP-9900, epoxy equivalent: 274 g/eq.) were blended and mixed. ., DIC Co., Ltd.), 7 parts by mass of bis(3-ethyl-5-methyl-4-maleimidodiphenyl)methane (product name: BMI-70, K.I. Chemical Co., Ltd.), 18 parts by mass of 2,4,5-triphenylimidazole (Tokyo Chemical Industry Co., Ltd.), and 0.5 parts by mass of 2,4,5-triphenylimidazole (Tokyo Chemical Industry Co., Ltd.) were added, and then diluted with methyl ethyl ketone to obtain a varnish A which is a solution of a resin composition. The obtained varnish A was applied to the matte side of a 12 μm thick copper foil (product name: 3EC-M2S-VLP, Mitsui Metal & Mining Co., Ltd.) using a coating bar to obtain a coating film. Then, the coated film was heated and dried at 150°C for 10 minutes, thereby obtaining a resin-coated copper foil on which a first resin layer was formed.

36 parts by mass of biphenyl aralkyl phenolic resin (product name: KAYAHARD GPH-103, hydroxyl equivalent: 231 g/eq., manufactured by Nippon Kayaku Co., Ltd.), 39 parts by mass of biphenyl aralkyl epoxy resin (product name: NC-3000-FH, manufactured by Nippon Kayaku Co., Ltd., epoxy equivalent: 320 g/eq.), 39 parts by mass of naphthalene aralkyl epoxy resin (product name: HP-9900, epoxy equivalent: 274 g/eq., manufactured by DIC (co., Ltd.) 7 parts by mass, bis(3-ethyl-5-methyl-4-maleimidodiphenyl)methane (product name: BMI-70, manufactured by K.I. Chemicals Co., Ltd.) 18 parts by mass, slurry silica (product name: SC2050-MB, average particle size 0.7 μm, manufactured by Admatechs Co., Ltd.) 300 parts by mass, styrene butadiene rubber (product name: JSR TR2003, JSR Co., Ltd.) 20 parts by mass, wetting dispersant 1 (product name: DISPERBYK-161, BYK Co., Ltd.) 1 part by mass, wetting dispersant 2 (product name: DISPERBYK-111, BYK Co., Ltd.) 2 parts by mass, silane coupling agent (product name: KBM-403, Shin-Etsu Chemical Co., Ltd.) 1 part by mass, 2,4,5-triphenylimidazole (Tokyo Chemical Industry Co., Ltd.) 0.5 part by mass, and then diluted with methyl ethyl ketone to obtain varnish B which is a solution of the resin composition. The obtained varnish B was applied to the first resin layer side of the resin-attached copper foil obtained in the above method using a coating bar to obtain a coating film. Then, the coating film was heated and dried at 150°C for 10 minutes to obtain a substrate (resin sheet) with an insulating resin layer having a first resin layer and a second resin layer in order from the substrate side. The thickness of the first resin layer was about 2.0 μm, and the thickness of the second resin layer was 5.1 μm.

[Comparative Example 2] 36 parts by mass of biphenyl aralkyl phenolic resin (product name: KAYAHARD GPH-103, hydroxyl equivalent: 231 g/eq., manufactured by Nippon Kayaku Co., Ltd.), 39 parts by mass of biphenyl aralkyl epoxy resin (product name: NC-3000-FH, manufactured by Nippon Kayaku Co., Ltd., epoxy equivalent: 320 g/eq.), 39 parts by mass of naphthalene aralkyl epoxy resin (product name: HP-9900, epoxy equivalent: 274 g/eq.) were blended and mixed. ., DIC Co., Ltd.), 7 parts by mass of bis(3-ethyl-5-methyl-4-maleimidodiphenyl)methane (product name: BMI-70, K.I. Chemical Co., Ltd.), 18 parts by mass of 2,4,5-triphenylimidazole (Tokyo Chemical Industry Co., Ltd.), and 0.5 parts by mass of 2,4,5-triphenylimidazole (Tokyo Chemical Industry Co., Ltd.) were added, and then diluted with methyl ethyl ketone to obtain a varnish A which is a solution of a resin composition. The obtained varnish A was applied to the matte side of a 12 μm thick copper foil (product name: 3EC-M2S-VLP, Mitsui Metal & Mining Co., Ltd.) using a coating bar to obtain a coating film. Then, the coated film was heated and dried at 150°C for 10 minutes, thereby obtaining a resin-coated copper foil on which a first resin layer was formed.

Then, 36 parts by weight of biphenyl aralkyl phenolic resin (product name: KAYAHARD GPH-103, hydroxyl equivalent: 231 g/eq., manufactured by Nippon Kayaku Co., Ltd.), 39 parts by weight of biphenyl aralkyl epoxy resin (product name: NC-3000-FH, manufactured by Nippon Kayaku Co., Ltd., epoxide equivalent: 320 g/eq.), and 39 parts by weight of naphthalene aralkyl epoxy resin (product name: HP-9900, epoxide equivalent: 274 g/eq., manufactured by DIC (co., Ltd.) 7 parts by mass, bis(3-ethyl-5-methyl-4-maleimidodiphenyl)methane (product name: BMI-70, manufactured by K.I. Chemicals Co., Ltd.) 18 parts by mass, slurry silica (product name: SC2050-MB, average particle size 0.7 μm, manufactured by Admatechs Co., Ltd.) 420 parts by mass, styrene butadiene rubber (product name: JSR TR2003, manufactured by JSR Co., Ltd.) 40 parts by mass, wetting and dispersing agent 1 (product name: DISPERBYK-161, manufactured by BYK Co., Ltd.) 1 part by mass, wetting and dispersing agent 2 (product name: DISPERBYK-111, manufactured by BYK Co., Ltd.) 2 parts by mass, silane coupling agent (product name: KBM-403, manufactured by Shin-Etsu Chemical Co., Ltd.) 1 part by mass, 2,4,5-triphenylimidazole (manufactured by Tokyo Chemical Industry Co., Ltd.) 0.5 part by mass, and then diluted with methyl ethyl ketone to obtain varnish B which is a solution of a resin composition. The obtained varnish B was applied to the first resin layer side of the resin-attached copper foil obtained in the above method using a coating bar to obtain a coating film. Then, the coating film was heated and dried at 150°C for 10 minutes to obtain a substrate (resin sheet) with an insulating resin layer having a first resin layer and a second resin layer in order from the substrate side. The thickness of the first resin layer was 2.0 μm, and the thickness of the second resin layer was 4.3 μm.

[Comparative Example 3] 60 parts by mass of block copolymer polyimide (product name: YN-003N, manufactured by PI Technology Laboratory) and 40 parts by mass of 2,2-bis-[4-(4-maleimide phenoxy)phenyl]propane (product name: BMI-80, manufactured by K.I. Chemical Industry Co., Ltd.) were blended and mixed, and then diluted with NMP to obtain varnish A which is a solution of a resin composition. The obtained varnish A was applied to the matte side of a 12μm thick copper foil (product name: 3EC-M2S-VLP, manufactured by Mitsui Metals & Mining Co., Ltd.) using a coating bar to obtain a coating film. Then, the coated film was heated and dried at 180° C. for 10 minutes, thereby obtaining a resin-coated copper foil on which a first resin layer was formed.

Then, 36 parts by weight of biphenyl aralkyl phenolic resin (product name: KAYAHARD GPH-103, hydroxyl equivalent: 231 g/eq., manufactured by Nippon Kayaku Co., Ltd.), 39 parts by weight of biphenyl aralkyl epoxy resin (product name: NC-3000-FH, manufactured by Nippon Kayaku Co., Ltd., epoxide equivalent: 320 g/eq.), and 39 parts by weight of naphthalene aralkyl epoxy resin (product name: HP-9900, epoxide equivalent: 274 g/eq., manufactured by DIC (co., Ltd.) 7 parts by mass, bis(3-ethyl-5-methyl-4-maleimidophenyl)methane (product name: BMI-70, manufactured by K.I. Chemicals Co., Ltd.) 18 parts by mass, slurry silica (product name: SC2050-MB, average particle size 0.7 μm, manufactured by Admatechs Co., Ltd.) 300 parts by mass, styrene butadiene rubber (product name: JSR TR2003, JSR Co., Ltd.) 20 parts by mass, wetting dispersant 1 (product name: DISPERBYK-161, BYK Co., Ltd.) 1 part by mass, wetting dispersant 2 (product name: DISPERBYK-111, BYK Co., Ltd.) 2 parts by mass, silane coupling agent (product name: KBM-403, Shin-Etsu Chemical Co., Ltd.) 1 part by mass, 2,4,5-triphenylimidazole (Tokyo Chemical Industry Co., Ltd.) 0.5 part by mass, and then diluted with methyl ethyl ketone to obtain varnish B which is a solution of the resin composition. The obtained varnish B (resin composition) was applied to the first resin layer side of the resin-attached copper foil obtained in the above method using a coating bar to obtain a coating film. Then, the coating film was heated and dried at 150°C for 10 minutes to obtain a substrate (resin sheet) with an insulating resin layer having a first resin layer and a second resin layer in order from the substrate side. The thickness of the first resin layer was 2.5 μm, and the thickness of the second resin layer was 5.1 μm.

[Comparative Example 4] 30 parts by mass of block copolymer polyimide (product name: YN-003N, manufactured by PI Technology Laboratory) and 60 parts by mass of 2,2-bis-[4-(4-maleimide phenoxy)phenyl]propane (product name: BMI-80, manufactured by K.I. Chemical Industry Co., Ltd.) were blended and mixed, and then diluted with NMP to obtain varnish A which was a solution of a resin composition. The obtained varnish A was applied to the matte side of a 12μm thick copper foil (product name: 3EC-M2S-VLP, manufactured by Mitsui Metals & Mining Co., Ltd.) using a coating bar to obtain a coating film. Then, the coated film was heated and dried at 180° C. for 10 minutes, thereby obtaining a resin-coated copper foil on which a first resin layer was formed.

Then, 36 parts by weight of biphenyl aralkyl phenolic resin (product name: KAYAHARD GPH-103, hydroxyl equivalent: 231 g/eq., manufactured by Nippon Kayaku Co., Ltd.), 39 parts by weight of biphenyl aralkyl epoxy resin (product name: NC-3000-FH, manufactured by Nippon Kayaku Co., Ltd., epoxide equivalent: 320 g/eq.), and 39 parts by weight of naphthalene aralkyl epoxy resin (product name: HP-9900, epoxide equivalent: 274 g/eq., manufactured by DIC (co., Ltd.) 7 parts by mass, bis(3-ethyl-5-methyl-4-maleimidophenyl)methane (product name: BMI-70, manufactured by K.I. Chemicals Co., Ltd.) 18 parts by mass, slurry silica (product name: SC2050-MB, average particle size 0.7 μm, manufactured by Admatechs Co., Ltd.) 300 parts by mass, styrene butadiene rubber (product name: JSR TR2003, JSR Co., Ltd.) 20 parts by mass, wetting dispersant 1 (product name: DISPERBYK-161, BYK Co., Ltd.) 1 part by mass, wetting dispersant 2 (product name: DISPERBYK-111, BYK Co., Ltd.) 2 parts by mass, silane coupling agent (product name: KBM-403, Shin-Etsu Chemical Co., Ltd.) 1 part by mass, 2,4,5-triphenylimidazole (Tokyo Chemical Industry Co., Ltd.) 0.5 part by mass, and then diluted with methyl ethyl ketone to obtain varnish B which is a solution of the resin composition. The obtained varnish B (resin composition) was applied to the first resin layer side of the resin-attached copper foil obtained in the above method using a coating bar to obtain a coating film. Then, the coating film was heated and dried at 150°C for 10 minutes to obtain a substrate (resin sheet) with an insulating resin layer having a first resin layer and a second resin layer in order from the substrate side. The thickness of the first resin layer was 4 μm, and the thickness of the second resin layer was 5.1 μm.

<Characteristics> The properties of the substrate with insulating resin layer were measured using the following method.

[Production of inner circuit substrate] The inner circuit substrate was obtained by roughening the copper foil surfaces of both sides of a glass cloth-based BT resin double-sided copper-clad laminate (copper foil thickness 12μm, thickness 0.2mm, Mitsubishi Gas Chemical Co., Ltd., product name: CCL-HL832NS) with an inner circuit having a copper residual rate of 60% by using a pretreatment liquid (MEC Co., Ltd., product name: CZ8100).

[Manufacturing of metal-clad laminate] Two substrates with insulating resin layers are arranged so that the surface of the second resin layer faces the inner circuit substrate and sandwiches the inner circuit substrate. Then, the laminate is formed at a pressure of 3.0 MPa and a temperature of 220°C for 60 minutes to obtain a copper-clad laminate.

[Measurement of thickness reduction (TΔ)] The copper-clad laminate obtained as described above was polished in a direction parallel to its lamination direction and a cross section was exposed to obtain a sample. The thickness of the first resin layer of the obtained sample was measured using a scanning electron microscope (SEM), and the thickness reduction was evaluated by comparing it with the thickness of the first resin layer in the substrate with an insulating resin layer. The thickness reduction (TΔ) of the first resin layer was calculated as described above from the thickness of the first resin layer of the substrate with an insulating resin layer and the thickness of the first resin layer of the copper-clad laminate. For the second resin layer, calculate the thickness reduction in the same way as above.

[Formability (filling property) of printed wiring boards] The copper foil on both sides of the copper-clad laminate was removed by etching to obtain a sample. The surface of the obtained sample was visually observed to evaluate the presence of pores. Here, pores refer to areas with gaps and no resin. When the presence of pores is confirmed to be large, specifically, when the area occupied by pores in the observation area is more than 30% relative to the average resin, it is considered to be impossible to form and is evaluated as "C". Although the presence of pores can be confirmed, when the number is small, specifically, when the area occupied by pores in the observation area is less than 30% relative to the average resin, it is considered to be formable and is evaluated as "B". When the presence of voids was not confirmed, the mold was considered to be good and the evaluation was A. The results are shown in Table 1.

《Minimum melt viscosity of resin sheet》 The minimum melt viscosity of the second resin layer in the substrate with insulating resin layer obtained as described above was measured using a rheometer (manufactured by TA Instruments Japan Co., Ltd.) at a starting temperature of 80°C, an end temperature of 180°C, a heating rate of 3°C/min, a frequency of 10 pts/s, and a strain of 0.1%. The lower the minimum melt viscosity, the better the flow characteristics (resin fluidity) during the production of the laminate, and the better the formability. The results of the minimum melt viscosity of the second resin layer are shown in Table 1.

"Insulation reliability evaluation" (Production of inner circuit substrate for insulation reliability evaluation) The copper foil surfaces on both sides of a glass cloth-based BT resin double-sided copper-clad laminate (copper foil thickness 12μm, thickness 0.2mm, Mitsubishi Gas Chemical Co., Ltd., product name: CCL-HL832NS) with an inner circuit for insulation reliability evaluation formed by a subtractive method were roughened using a pretreatment liquid (MEC Co., Ltd., product name: CZ8101) to obtain an inner circuit substrate for insulation reliability evaluation.

(Preparation of a substrate for insulation reliability evaluation) The substrate with an insulating resin layer is arranged so that the surface of the second resin layer faces the inner circuit substrate for insulation reliability evaluation and the inner circuit substrate is clamped. Then, lamination molding is performed at a pressure of 3.0 MPa and a temperature of 220°C for 120 minutes to obtain a copper-clad laminate with an insulation layer thickness of 5 μm. The outer circuit for insulation reliability evaluation is manufactured from the copper-clad laminate by a subtractive method to obtain a substrate for insulation reliability evaluation.

-Insulation reliability evaluation method- The above-mentioned insulation reliability evaluation substrate was subjected to moisture absorption treatment at 85℃, 60%RH for 168 hours, and then reflow treatment was performed at 260℃ for 3 times. For the insulation reliability evaluation substrate after reflow treatment, the final resistance value when the resistance value was measured for 96 hours under HAST conditions (130℃, 85%RH, 5.0V) was calculated, and the evaluation was performed in accordance with the following standards while visually observing during the measurement. <Standard>"A": No short circuit occurred during the measurement, and the final resistance value was 1.0×10 ⁸ Ω or more. "B": No short circuit occurred during the measurement, and the final resistance value did not reach 1.0×10 ⁸ Ω. "C": Short circuit occurred during the measurement. The results are shown in Table 1.

[Table 1] Embodiment 1 Embodiment 2 Embodiment 3 Embodiment 4 Embodiment 5 Embodiment 6 Embodiment 7 Embodiment 8 Embodiment 9 Reviews 1st resin layer Thickness reduction (%) 20 20 20 25 20 25 20 twenty three twenty three Thickness in copper-clad laminate (μm) 2.0 2.0 2.0 1.9 2.0 2.0 2.0 1.4 1.4 Second resin layer Thickness reduction (%) 44 41 36 41 44 44 38 38 38 Thickness in copper-clad laminate (μm) 3.0 3.0 3.0 3.0 5.0 3.0 3.0 2.0 1.0 Minimum melt viscosity (Pa･s) 100 60,000 110,000 60,000 100 100 80,000 80,000 80,000 Insulation reliability A A A A A A A A B Formability (filling properties) A A B A A A B B B Embodiment 10 Embodiment 11 Embodiment 12 Embodiment 13 Comparison Example 1 Comparison Example 2 Comparison Example 3 Comparison Example 4 Reviews 1st resin layer Thickness reduction (%) 20 20 20 20 44 44 40 52 Thickness in copper-clad laminate (μm) 2.0 2.0 2.0 2.0 1.1 1.1 1.5 1.9 Second resin layer Thickness reduction (%) 44 44 44 38 41 31 41 41 Thickness in copper-clad laminate (μm) 13.0 10.0 8.0 2.5 3.0 3.0 3.0 3.0 Minimum melt viscosity (Pa･s) 100 100 100 100 60,000 150,000 60,000 60,000 Insulation reliability A A A B C C C C Formability (filling properties) A A A B A C B B

As shown in Table 1, in the embodiment, the insulation reliability and the embedding property are all better than B or above. On the other hand, in the comparative example where the thickness of the first resin layer is reduced by more than 30%, the insulation reliability is as low as C. In addition, in the comparative example 2 where the minimum melt viscosity of the second resin layer is 150,000 Pa･s, the embedding property is as poor as C. [Industrial Usability]

According to the present invention, a base material with an insulating resin layer useful for printed wiring boards or semiconductor device mounting substrates, a laminate using the same, and a method for producing the laminate can be provided, and the present invention has industrial applicability in these fields.

10: Base material with resin layer 12: Base material 14: First resin layer 16: Second resin layer 20: Inner circuit board 22: Base board 24: Conductor layer 30: Laminated body 100: Multi-layer coreless substrate 111,112: Insulation layer 113: Conductor layer

[Figure 1] (A) ~ (B) are schematic diagrams for explaining the reduction in thickness of the first resin layer in this embodiment. [Figure 2] is a schematic diagram showing an example of a multi-layer coreless substrate in this embodiment.

Claims (19)

A substrate with an insulating resin layer comprises: a substrate, a first resin layer disposed on the substrate, and having a thickness reduction of less than 30% when formed at 220°C and 3.0 MPa under pressure for 60 minutes, and a second resin layer disposed on the first resin layer; the first resin layer contains 50 to 500 parts by mass of a filler relative to 100 parts by mass of the resin solid component. For a substrate with an insulating resin layer as in claim 1, the minimum melt viscosity of the second resin layer is less than 100,000 Pa.s. For a substrate with an insulating resin layer as claimed in claim 1 or 2, the thickness of the first resin layer is less than 10 μm. A substrate with an insulating resin layer as claimed in claim 1 or 2, wherein the thickness of the second resin layer is greater than 2.0 μm. A substrate with an insulating resin layer as claimed in claim 1 or 2, wherein the combined thickness of the first resin layer and the second resin layer is greater than 3 μm and less than 20 μm. The substrate with an insulating resin layer as claimed in claim 1 or 2, wherein the first resin layer contains a material selected from the group consisting of polyimide, liquid crystal polyester, epoxy resin, cyanate ester compound, maleimide compound, phenolic resin, thermosetting modified polyphenylene ether resin, benzophenone

At least one of the group consisting of a compound, an organic-modified polysiloxane compound, and a compound having a polymerizable unsaturated group. The substrate with an insulating resin layer as claimed in claim 1 or 2, wherein the second resin layer contains a material selected from epoxy resin, cyanate compound, maleimide compound, phenolic resin, thermosetting modified polyphenylene ether resin, benzoic acid

At least one of the group consisting of compounds, organic-modified polysiloxane compounds and compounds having polymerizable unsaturated groups. The substrate with an insulating resin layer as in claim 1 or 2 is used for the production of a coreless substrate to be mounted on a printed wiring board or a semiconductor component mounting substrate. A substrate with an insulating resin layer as claimed in claim 8, wherein the coreless substrate is a 3-layer coreless substrate. A laminate having a stacking layer, the stacking layer being a stacking layer of a conductive layer and an insulating layer formed by using a substrate with an insulating resin layer as in claim 1 or 2. The laminated body of claim 10, wherein the thickness of at least one insulating layer is greater than 1 μm and less than 15 μm. The stacked body of claim 10, wherein the stacked layer has multiple layers of the conductive layer and the insulating layer, and the conductive layer is arranged between each of the insulating layers and on the surface of the outermost layer of the stacked layer. The stacked body of claim 10, wherein in the stacked layer, the conductive layer and the insulating layer are alternately stacked, and the stacked layer has 3 or 4 insulating layers. The stacked body of claim 10 is a coreless substrate. A method for manufacturing a laminated body, comprising the steps of forming a stacked layer consisting of a conductive layer and the insulating layer by forming an insulating layer on the surface of a conductive layer using a substrate with an insulating resin layer as in claim 1 or 2. A method for manufacturing a laminate as claimed in claim 15, wherein the thickness of at least one insulating layer is greater than 1 μm and less than 15 μm. A method for manufacturing a stacked body as claimed in claim 15, wherein the stacked layer has multiple layers of the conductive layer and the insulating layer, and the conductive layer is arranged between each of the insulating layers and on the surface of the outermost layer of the stacked layer. A method for manufacturing a laminate as claimed in claim 15, wherein the insulating layer has 3 or 4 layers. A method for manufacturing a laminate as claimed in claim 15, wherein the laminate is a coreless substrate.

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