JPH10107435A - Printed wiring board and manufacturing method thereof and plate resist composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a printed wiring board with improved adhesion between a plate resist and a conductor circuit and improved reliability of heat-cycle characteristics, etc., and to provide a plate resist composition advantageous to improve adhesion with the conductor circuit. SOLUTION: A printed wiring board comprises a conductor circuit 7 provided via a plate resist 6 in a part, wherein the plate resist is not formed on the surface of resin insulating layers 3, 4 formed on a substrate 1. The resin component of the plate resist 6 is a resin composite substance consists of a thermoplastic resin and a photosensitive resin, the side wall surface of the plate resist 6 brought into contact with the conductor circuit 7 is made rough. The plate resist composition material contains acrylate of a cresol-novolak tape epoxy- resin, an imidazole curing agent, and a thermoplastic resin as the main components.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a printed wiring board, a method for producing the same, and a plating resist composition, and more particularly to a printed wiring board excellent in reliability such as adhesion between a plating resist and a conductor circuit and heat cycle characteristics. And a method for advantageously producing this printed wiring board, and at the same time, a plating resist composition that is advantageous for improving the adhesion to a conductor circuit.

[0002]

2. Description of the Related Art In an additive wiring board, a resin insulating layer (adhesive layer for electroless plating) is formed on a substrate, a plating resist is formed on a portion where a conductor pattern is not formed, and then a portion where a plating resist is not formed. It is manufactured through a process including a series of processes of forming a conductor circuit by performing electroless plating on the substrate.

The plating resist formed on the additive wiring board is composed of a layer of a resin composition comprising an acrylate of a cresol novolak type epoxy resin and an imidazole curing agent, as disclosed in Japanese Patent Application Laid-Open No. Hei 6-3179045. Is known.

In such an additive wiring board, the plating resist is composed of a layer of a resin composition, while the conductor circuit is composed of a metal layer. Has a significantly different coefficient of thermal expansion. Conventionally, a plating resist has a smooth side wall surface in contact with a conductor circuit due to a demand for a fine pattern.

[0005]

Therefore, in the case of a printed wiring board in which a plating resist is left as a permanent resist on a substrate, good adhesion is obtained because the side wall surface between the plating resist and the conductor circuit is smooth because it is smooth. However, there was a problem that cracks were generated toward the resin insulating layer (adhesive layer for electroless plating) by heat cycles because the thermal expansion coefficients were different from each other.

In addition, in the case of a printed wiring board in which a surface of a wiring board provided with a conductive circuit in a portion where no resist is formed via a plating resist is polished and smoothed, and a resin insulating layer and a conductive circuit are further formed thereon. Also, there is a problem that cracks are generated from the interface between the plating resist and the conductor circuit toward the resin insulating layer by the heat cycle. The reason is considered that the conductor circuit is plastically deformed in the polishing direction by polishing, and a protrusion is formed, and stress is concentrated on the protrusion due to a difference in thermal expansion coefficient between the plating resist and the conductor circuit, and cracks are generated from this. Can be

The main object of the present invention is to solve the above-mentioned problems of the prior art and to provide not only excellent heat resistance and electrical characteristics, but also extremely excellent adhesion between a plating resist and a conductor circuit, and heat resistance. An object of the present invention is to provide a printed wiring board excellent in reliability such as cycle characteristics and a method for advantageously manufacturing the printed wiring board. Another object of the present invention is to provide a plating resist composition having a component composition that is advantageous for improving the adhesion between a plating resist and a conductive circuit in a printed wiring board.

[0008]

Means for Solving the Problems The inventor of the present invention has made intensive studies for realizing the above-mentioned object, and as a result, has completed the invention having the following features as the gist. That is, (1) The printed wiring board of the present invention is a printed wiring board comprising a conductive circuit provided on a surface of a resin insulating layer formed on a substrate, on a portion where no plating resist is formed, via a plating resist. The resist is characterized in that a resin composite composed of a thermoplastic resin and a photosensitive resin is used as a resin component, and a sidewall portion of the plating resist that contacts a conductor circuit is roughened.

Here, in the printed wiring board according to the present invention, the resin insulating layer is preferably an adhesive layer for electroless plating, and the surface of the plating resist is flush with the surface of the conductor circuit. It is desirable that the surface be polished so as to be on top and smoothed.

(2) In the method of manufacturing a printed wiring board according to the present invention, a resin insulating layer is formed on a substrate,
In a method for manufacturing a printed wiring board, in which a plating resist is formed on a portion of a resin insulating layer surface excluding a conductor pattern, and then a conductor circuit is formed by electroless plating on a portion where no plating resist is formed, in forming the plating resist, A composition containing a mixed resin of a thermoplastic resin and a photosensitive resin as a resin component is applied thereon, dried, exposed, developed and cured, and at the same time, the surface including the side walls of the plating resist is removed with a solvent. Wherein only the thermoplastic resin portion of the mixed resin is dissolved and removed to roughen the mixed resin.

Here, in the manufacturing method according to the present invention, it is preferable that the resin insulating layer is formed using an adhesive for electroless plating, and the surface of the plating resist is in contact with the surface of the conductor circuit. It is desirable that the surface is polished and smoothed so as to be on the same plane.

(3) The plating resist composition of the present invention is characterized by containing, as main components, an acrylate of cresol novolak type epoxy resin, an imidazole curing agent and a thermoplastic resin.

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention is characterized in that a resin composite comprising a thermoplastic resin and a photosensitive resin is used as a resin component constituting a plating resist. The reason for using such a plating resist when electroless plating a printed wiring board is that when forming an electroless plating film on a substrate,
This is because the adhesion strength between the plated conductor and the resist is increased, and a highly reliable conductor pattern is obtained.

That is, a composition (plating resist composition) containing a mixed resin of a thermoplastic resin and a photosensitive resin as a resin component is applied on a substrate, dried, exposed, developed, and cured to obtain a photosensitive composition. A plating resist containing a resin composite in which a thermoplastic resin is dispersed in a resin matrix of a conductive resin as a resin component is formed in a portion where a conductor pattern is not formed. On the other hand, when the plating resist is treated with a solvent, the photosensitive resin of the resin composite does not dissolve in the solvent, and only the thermoplastic resin of the resin composite existing on the surface portion of the plating resist is dissolved in the solvent. To selectively dissolve away.

As a result, the surface including the side wall of the plating resist is roughened due to the formation of anchors (dents).
As described above, when the portion of the plating resist that comes into contact with the plating conductor is roughened, plating is deposited on the rough surface to form a conductor, so that the plating resist and the plating conductor are firmly adhered to each other, and as a result, heat is applied. Even during the cycle, no stress is generated in the resin insulating layer in contact with the interface between the conductor circuit and the plating resist, and no crack is generated.

Also, in the case of a printed wiring board in which the surface of a wiring board provided with a conductive circuit in a portion where no plating resist is formed via a plating resist is polished and smoothed, and further a resin insulating layer and a conductive circuit are formed thereon In addition, the polished plating resist and the conductor circuit can be maintained in a completely adhered state, and no crack is generated from the interface between the plating resist and the conductor circuit toward the resin insulating layer due to the heat cycle.

In the present invention, the resin composite containing a thermoplastic resin and a photosensitive resin as a resin component has a structure in which the thermoplastic resin and the photosensitive resin are phase-separated, for example, a spherical domain structure or a bicontinuous structure. It is desirable that the resin composite has the following. Here, the globular domain structure is
The term “co-continuous structure” refers to a structure in which thermoplastic resin islands are dispersed in the sea of photosensitive resin, and spherical particles of thermoplastic resin are continuously connected in a matrix of photosensitive resin to form one phase. Means the structure in which is formed. In the resin composite having these structures, since the thermoplastic resin phase is clearly present in the photosensitive resin matrix, when this is treated with a solvent, only the thermoplastic resin is selectively dissolved and removed, and the resist surface is removed. A roughened surface having clear irregularities (anchors) can be formed.

In the present invention, the plating resist containing the above resin composite as a resin component is prepared by applying a plating resist composition containing a mixed resin of a thermoplastic resin and a photosensitive resin as a resin component on a substrate, followed by drying. Next, this is formed by exposing, developing and hardening it. here,
The photosensitive resin is preferably an acrylate of a novolak type epoxy resin. This is because novolak-type epoxy resins have a rigid skeleton and are excellent in base resistance. As the novolak epoxy resin, cresol novolak epoxy resin and phenol novolak epoxy resin are preferable. Examples of the thermoplastic resin include polyether sulfone, polystyrene, polyethylene, polyvinyl chloride, and the like.

It is desirable to use an imidazole curing agent as a curing agent for the photosensitive resin which is a resin component of the plating resist composition. In particular, an epoxy resin cured with an imidazole curing agent is excellent in heat resistance and chemical resistance, and is excellent in properties with respect to a base.

The imidazole curing agent is desirably liquid at 25.degree. This is because uniform kneading is difficult with powder, and liquid can be kneaded more uniformly. Examples of such a liquid imidazole curing agent include 1-benzyl-2-methylimidazole (product name: 1B2MZ), 1-cyanoethyl-2-ethyl
-4-methylimidazole (product name: 2E4MZ-CN), 4-methyl
2-ethylimidazole (product name: 2E4MZ). The addition amount of the imidazole curing agent is desirably 1 to 10% by weight. The reason for this is that if the added amount is within this range, uniform mixing is easy.

The plating resist composition according to the present invention further includes benzophenone as an initiator, Michler's ketone as a sensitizer, and heat resistance for improving heat resistance and base resistance and imparting flexibility. A curable resin, a photosensitive monomer for improving resolution, and an acrylate polymer as a leveling agent can be added and mixed.

Benzophenone as an initiator (photopolymerization initiator) and Michler's ketone as a sensitizer (photopolymerization auxiliary) are
It is desirable to dissolve them in a heated glycol ether-based solvent at the same time, and to make them compatible with a resin mixture (plating resist composition) of a photosensitive resin and a thermoplastic resin. This is because the use of only Michler's ketone has low solubility in the above-mentioned solvent, causes a dissolved residue even when heated, and precipitates at room temperature. The reason why benzophenone and Michler's ketone are completely dissolved when mixed together in the above solvent is as follows:
Although unknown, it is presumed that benzophenone and Michler's ketone have a structure similar to a complex in a solvent, and that the formation of a structure similar to this complex may enhance the solubility of Michler's ketone. According to such a method, since benzophenone and Michler's ketone are completely dissolved in the glycol ether-based solvent, the resin mixture in which the benzophenone and the Michler's ketone are compatible becomes a homogeneous phase. As a result, the unexposed portion of the layer of the resin mixture can be completely removed by exposure and development.

The glycol ether solvent for dissolving benzophenone and Michler's ketone is preferably diethylene glycol dimethyl ether (DMDG) and / or triethylene glycol dimethyl ether (DMTG). This is because these solvents can completely dissolve benzophenone and Michler's ketone by heating at about 30 to 50 ° C.

The thermosetting resin as an additional component is preferably a bisphenol type epoxy resin. This is because a bisphenol-type epoxy resin can improve base resistance. The bisphenol type epoxy resin includes a bisphenol A type epoxy resin and a bisphenol F type epoxy resin, and the former is better when the basic resistance is important, and the latter is better when the applicability is important.

The acrylate polymer as an additive component can make the whole plating resist composition uniform. In this case, the kneading performed to obtain a liquid resist as in the related art becomes unnecessary. According to such an acrylate polymer, there is no need to disperse an antifoaming agent in the resist composition, so that the resist surface can be smoothened without developing residue. Here, the acrylate polymer is a polymer obtained by polymerizing one or more esters of an ester of acrylic acid or methacrylic acid with an alcohol having a molecular weight of 500 to 5,000.

In the present invention, the plating resist composition containing the above-mentioned additional components is preferably prepared by simultaneously dissolving and mixing benzophenone and Michler's ketone in a heated glycol ether-based solvent to prepare a mixed solution. By mixing the liquid and novolak type epoxy resin acrylate, thermoplastic resin and imidazole curing agent, and further mixing acrylate polymer, photosensitive monomer, bisphenol type epoxy resin, etc. as necessary, to prepare a uniform solution can get.

In the present invention, the surface of the plating resist formed using the above-described plating resist composition is roughened by dissolving and removing only the thermoplastic resin portion by treating the surface including the side wall with a solvent. .

Here, the solvent used for roughening the surface of the plating resist includes glycol ether solvents such as DMDG (diethylene glycol dimethyl ether) and DMTG (triethylene glycol dimethyl ether), and NMP (N-methylpyrrolidone). ) Or DM
F (dimethylformamide), methylene chloride and the like.

Hereinafter, a method for manufacturing a printed wiring board according to the present invention will be described. (1) First, an inner layer copper pattern is formed on the surface of the core substrate. The formation of a copper pattern on this substrate is performed by etching a copper-clad laminate, or an adhesive layer for electroless plating is formed on a substrate such as a glass epoxy substrate, a polyimide substrate, a ceramic substrate, and a metal substrate, There is a method in which the surface of the adhesive layer is roughened to a roughened surface, and electroless plating is performed thereon. Note that a through hole is formed in the core substrate, and the wiring layer on the front surface and the back surface can be electrically connected through the through hole.

(2) Next, a resin insulating layer is formed on the substrate on which the inner layer copper pattern has been formed in (1). In particular, in the present invention, it is desirable to use an adhesive layer for electroless plating as the resin insulating layer.

The adhesive for electroless plating is obtained by dispersing cured heat-resistant resin particles soluble in acid or oxidizing agent in uncured heat-resistant resin hardly soluble in acid or oxidizing agent. Optimal. This is because, by dissolving and removing the heat-resistant resin particles soluble in an acid or an oxidizing agent, an octopus-shaped anchor can be formed on the surface and the adhesion to the conductor circuit can be improved.

In the above-mentioned adhesive for electroless plating, the heat-resistant resin which is hardly soluble in an acid or an oxidizing agent is preferably a sensitized thermosetting resin or a composite of a sensitized thermosetting resin and a thermoplastic resin. . Exposure by photosensitization,
This is because via holes can be easily formed by development. In addition, by forming a composite with a thermoplastic resin, the toughness can be improved, and the peel strength of the conductor circuit can be improved,
This is because the occurrence of cracks in the via holes due to the heat cycle can be prevented. Specifically, epoxy acrylate obtained by reacting an epoxy resin with acrylic acid, methacrylic acid, or the like, or a composite of epoxy acrylate and polyether sulfone is preferable. The epoxy acrylate is preferably one in which 20 to 80% of all epoxy groups have reacted with acrylic acid or methacrylic acid.

In the above-mentioned adhesive for electroless plating, the heat-resistant resin particles include a heat-resistant resin powder having an average particle diameter of 10 μm or less and a heat-resistant resin powder having an average particle diameter of 2 μm or less. Agglomerated particles having a size of 2 to 10 μm, a mixture of a heat-resistant resin powder having an average particle size of 10 μm or less and a heat-resistant resin powder having an average particle size of 2 μm or less, and a heat-resistant resin powder having an average particle size of 2 to 10 μm It is desirable to select from pseudo particles obtained by adhering at least one of a heat-resistant resin powder and an inorganic powder having an average particle diameter of 2 μm or less on the surface. These are because they can form complex anchors. As the resin of the heat-resistant resin particles, epoxy resin, amino resin (melamine resin, urea resin, guanamine resin) and the like are preferable. Particularly, the solubility of an epoxy resin in an acid or an oxidizing agent can be arbitrarily changed by changing the type of the oligomer, the type of the curing agent, and the crosslinking density. For example, a bisphenol A-type epoxy resin oligomer cured with an amine-based curing agent is easily dissolved in an oxidizing agent. However, the novolak epoxy resin oligomer cured with an imidazole-based curing agent is hardly dissolved in the oxidizing agent.

In the method of the present invention, the resin insulating layer does not need to be formed by one application, but may be formed by applying a plurality of times. For example, first, an uncured resin insulating material is applied, and after drying, an adhesive for electroless plating is further applied to form a two-layer resin insulating layer. The lower layer has an average particle size of 0.1 to 0.3 μm.
An adhesive layer for electroless plating containing the following heat-resistant resin powder was used. The upper layer contained a mixture of a heat-resistant resin powder having an average particle diameter of 10 μm or less and a heat-resistant resin powder having an average particle diameter of 2 μm or less. It is also possible to use a two-layered resin insulating layer as an adhesive layer for electrolytic plating.

(3) After drying the resin insulating layer formed in the above (2), the photosensitive resin is exposed and developed. By processing, an opening for a via hole is provided.

(4) After the surface of the resin insulating layer provided with the opening for via hole in (3) is roughened with an acid or an oxidizing agent, a catalyst nucleus is provided. Here, examples of the acid that can be used for the above-mentioned roughening treatment include phosphoric acid, hydrochloric acid, sulfuric acid, and organic acids such as formic acid and acetic acid, and organic acids are particularly desirable. This is because when the roughening treatment is performed, the metal conductor layer exposed from the via hole is hardly corroded. On the other hand, as the oxidizing agent, chromic acid and permanganate (such as potassium permanganate) are desirable. In particular, in the case of dissolving and removing the amino resin, it is preferable to perform a roughening treatment alternately with an acid and an oxidizing agent. In addition, it is desirable to use a noble metal ion or a noble metal colloid for providing the catalyst nucleus. Generally, palladium chloride or a palladium colloid is used.
Note that it is desirable to perform a heat treatment to fix the catalyst core. Palladium is preferred as such a catalyst core.

(5) After providing the catalyst nucleus in the above (4), a plating resist composition containing a mixed resin of a thermoplastic resin and a photosensitive resin as a resin component is applied to the substrate, dried, exposed,
A plating resist is formed by developing and curing.

(6) The surface including the side wall of the plating resist formed in the above (5) is roughened by dissolving and removing only the thermoplastic resin portion by treating with a solvent. Here, the dissolution and removal of the thermoplastic resin exposed on the surface of the plating resist is performed by means such as immersing the substrate having the plating resist in a solvent or spraying the substrate with the solvent.

(7) The primary plating is applied to the portion where the plating resist has not been formed by the processes (5) and (6). At this time, not only a copper pattern but also a via hole is formed.
The primary plating is desirably an alloy plating using at least two or more metal ions selected from copper, nickel, cobalt and phosphorus. This is because these alloys have high strength and can improve the peel strength. In the electroless plating solution for the primary plating, it is necessary to use at least two kinds of metal ions selected from copper, nickel and cobalt. The reason for this is that these alloys have high strength and peel strength. This is because it can be improved.

In the above electroless plating solution for the primary plating, it is desirable to use hydroxycarboxylic acid as a complexing agent for forming a stable complex with copper, nickel and cobalt ions under basic conditions. In the electroless plating solution for the primary plating, a reducing agent for reducing metal ions to a metal element is selected from aldehyde, hypophosphite (referred to as phosphinate), borohydride, and hydrazine. Desirably, at least one kind is used. This is because these reducing agents are water-soluble and have excellent reducing power. In particular, hypophosphite is desirable in terms of depositing nickel. In the electroless plating solution for the primary plating, at least one basic compound selected from sodium hydroxide, potassium hydroxide, and calcium hydroxide may be used as a pH adjuster for adjusting under basic conditions. desirable. This is because under basic conditions, hydroxycarboxylic acid forms a complex with nickel ions and the like. As the hydroxycarboxylic acid, citric acid, malic acid, tartaric acid and the like are desirable. This is because these easily form a complex with nickel, cobalt, and copper.
The concentration of the hydroxycarboxylic acid is preferably 0.1 to 0.8M. The reason for this is that if it is less than 0.1 M, a sufficient complex cannot be formed, resulting in abnormal precipitation and decomposition of the liquid. On the other hand, if it exceeds 0.8 M, problems such as a low deposition rate and an increase in generation of hydrogen occur.

The electroless plating solution for the primary plating desirably contains bipyridyl. The reason for this is that bipyridyl can suppress the generation of metal oxides in the plating bath and the generation of nodules. Note that copper ions, nickel ions, and cobalt ions are supplied by dissolving a compound of copper, nickel, and cobalt such as copper sulfate, nickel sulfate, cobalt sulfate, copper chloride, nickel chloride, and cobalt chloride.

The primary plating film formed by such an electroless plating solution has excellent followability to the roughened surface of the adhesive layer for electroless plating, and traces the form of the roughened surface as it is. Therefore, the primary plating film has an anchor like the roughened surface. Therefore, the adhesion of the secondary plating film formed on the primary plating film is secured by the anchor. Therefore, in order to control the peel strength, the primary plating film is desirably a plating film having a high strength to be deposited by the electroless plating solution as described above, while the secondary plating film has a high electric conductivity and a high deposition rate. Therefore, a plating film deposited with a simple copper plating solution is more desirable than composite plating.

(8) Secondary plating is performed on the primary plating film formed in (7) to form a conductor circuit including a via hole composed of the primary plating film and the secondary plating film. The plating film formed by the secondary plating is preferably a copper plating film. The electroless plating solution for the above-mentioned secondary plating has a copper ion concentration of 0.005 in an electroless plating solution comprising copper ions, trialkanolamine, a reducing agent and a pH adjuster.
~ 0.015mol / l, concentration of pH adjuster is 0.25 ~ 0.35mol
/ L, and it is preferable to use an electroless plating solution having a reducing agent concentration of 0.01 to 0.04 mol / l. This is because the plating solution has a stable bath and generates little nodules and the like. In the above electroless plating solution for secondary plating,
Desirably, the concentration of trialkanolamine is 0.1-0.8M. This is because the plating precipitation reaction most easily proceeds in this range. The trialkanolamine is desirably at least one selected from triethanolamine, triisopanolamine, trimethanolamine, and tripropanolamine. Because it is water-soluble. In the above electroless plating solution for secondary plating, the reducing agent is desirably at least one selected from aldehyde, hypophosphite, borohydride, and hydrazine. This is because it is water-soluble and has a reducing power under basic conditions. The pH adjuster is desirably at least one selected from sodium hydroxide, potassium hydroxide, and calcium hydroxide.

(9) Further, if necessary, the surface of the plating resist and the surface of the conductor circuit including via holes are polished so as to be on the same plane, and the processing of (2) to (8) is repeated, Obtain a desired multilayer printed wiring board. On the surface layer of the multilayer printed wiring board thus obtained, a plating resist is formed on the roughened surface of the resin insulating layer whose surface is roughened, and the side wall portion of the plating resist that contacts the conductor circuit is roughened. The structure is such that the conductor circuit is provided in a state where the conductive circuit is exposed on the non-formation surface of the plating resist. For this reason,
The exposed conductor circuit is protected by covering with a solder resist having an opening at a portion where a solder layer is to be formed.

(10) Then, nickel-gold plating is applied to a portion (pad portion) of the solder resist opening where the solder layer is to be formed, and the solder layer is formed on this portion by a solder transfer method or a screen printing method. Form. In addition,
The solder transfer method is a method in which a solder pattern is formed on a film, and the solder pattern is transferred to the pad by heating and reflowing while the solder pattern is in contact with the pad. Note that the solder layer may be a solder bump.

[0046]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to embodiments. (1) 18 μm on both sides of substrate 1 made of glass epoxy resin or BT (bismaleimide triazine) resin having a thickness of 1 mm
A copper-clad laminate obtained by laminating m copper foils 9 was used as a starting material (see FIG. 1 (a)). By etching the copper foil 9 of the copper-clad laminate in a pattern according to a conventional method, the inner layer copper pattern 2 was formed on both surfaces of the substrate 1 (see FIG. 1B).

(2) The substrate on which the inner layer copper pattern 2 has been formed in the above (1) is washed with water and dried, and then the substrate is acid-degreased and soft-etched. Then, a catalyst solution comprising palladium chloride and an organic acid is used. After treatment to give a Pd catalyst and activate this catalyst, plating is carried out in an electroless plating bath, and Cu-Ni-P
An uneven layer (roughened surface) having a thickness of 2.5 μm of the alloy was formed. Further, the substrate was washed with water and immersed in an electroless tin plating bath composed of a tin borofluoride-thiourea solution at 50 ° C. for 1 hour, and a 0.3 μm-thick surface was formed on the roughened surface of the Cu-Ni-P alloy.
m of the tin-substituted plating layer was formed.

(3) Cresol novolak epoxy resin
After mixing 70 parts by weight of a 25% acrylate (manufactured by Nippon Kayaku), 25 parts by weight of polyether sulfone (manufactured by Mitsui Toatsu), 4 parts by weight of benzophenone, 0.4 part by weight of Michler's ketone and an imidazole-based curing agent, N-methylpyrrolidone is mixed. (NM
While adding P), the viscosity is 30 Pa · s with a homodisper stirrer.
And kneaded with three rolls to obtain an interlayer insulating agent.

(4) 70 parts by weight of 25% acrylate of cresol novolac type epoxy resin (manufactured by Nippon Kayaku, molecular weight 2500) dissolved in DMDG (dimethyl glycol dimethyl ether), 30 parts by weight of polyether sulfone (PES), imidazole Curing agent (Shikoku Chemicals, trade name: 2E4MZ-
CN) 4 parts by weight, 10 parts by weight of caprolactone-modified tris (acroxyethyl) isocyanurate (trade name: Alonix M325) manufactured by Toagosei Co., Ltd., 5 parts by weight of benzophenone (Kanto Chemical) as a photoinitiator ,
0.5 parts by weight of Michler's ketone (Kanto Chemical) as a photosensitizer, 35 parts by weight of epoxy resin particles having an average particle size of 5.5 μm and 5 parts by weight of an epoxy resin particle having an average particle size of 0.5 μm were added to this mixture. After mixing, the mixture was mixed while adding normal methylpyrrolidone (NMP), adjusted to a viscosity of 2000 cps with a homodisper stirrer, and then kneaded with three rolls to obtain a photosensitive adhesive solution.

(5) The interlayer insulating agent obtained in the above (3) is
Using a roll coater, both surfaces of the substrate after the treatment of (2) were applied, left in a horizontal state for 20 minutes, and then dried (prebaked) at 60 ° C. to form an insulating layer 3. Further, the photosensitive adhesive solution obtained in the above (4) is applied on the insulating layer 3 by using a roll coater, left in a horizontal state for 20 minutes, and then dried (prebaked) at 60 ° C. Then, an adhesive layer 4 was formed (see FIG. 1 (c)).

(6) A photomask film on which via holes are drawn is placed on both sides of the substrate on which the interlayer resin insulating layer composed of the insulating layer 3 and the adhesive layer 4 is formed in the above (5), and ultraviolet rays are applied. Irradiate and expose. (7) The exposed substrate was spray-developed with triethylene glycol dimethyl ether (DMTG) to form an opening as a 100 μmφ via hole in the interlayer resin insulating layer. Furthermore, the substrate is 3,000 mJ with an ultra-high pressure mercury lamp.
/ Cm ² , and heat treatment at 100 ° C. for 1 hour and then at 150 ° C. for 5 hours to obtain a 50 μm-thick film having an opening (via hole forming opening 5) with excellent dimensional accuracy equivalent to a photomask film. Interlayer resin insulation layer (two-layer structure)
Was formed. Note that the tin plating layer is partially exposed in the opening serving as the via hole.

(8) The substrate having the via hole forming openings 5 formed in (6) and (7) is immersed in chromic acid for 2 minutes, and then the epoxy resin particles in the interlayer resin insulating layer are dissolved. ,
The surface of the interlayer resin insulation layer was roughened, and then immersed in a neutralizing solution (manufactured by Shipley) and washed with water (FIG. 1 (d)).
reference).

(9) The surface roughening treatment (roughening depth 20 μm)
By applying a palladium catalyst (manufactured by Atotech) to the substrate subjected to m), catalyst nuclei were attached to the surfaces of the interlayer resin insulating layer and the via hole openings.

(10) 46.67 g of a photosensitizing oligomer (molecular weight 4000) obtained by acrylizing 50% of an epoxy group of a cresol novolak type epoxy resin (manufactured by Nippon Kayaku) in 60 parts by weight of DMDG dissolved in methyl ethyl ketone. 15.0 g of 80 parts by weight of dissolved bisphenol A type epoxy resin (manufactured by Yuka Shell, Epicoat 1001), 1.6 g of imidazole hardener (manufactured by Shikoku Chemicals, trade name: 2E4MZ-CN), polyvalent acrylic as a photosensitive monomer 3 g of a monomer (manufactured by Nippon Kayaku, trade name: R604) and 1.5 g of a polyvalent acrylic monomer (manufactured by Kyoeisha Chemical, trade name: DPE6A) were further mixed, and 0.5 part by weight of 2 parts by weight based on the total weight of these mixtures. -0.36 g of acrylate polymer consisting of ethylhexyl acrylate, butyl acrylate, ethyl acrylate and hydroxy acrylate, dissolved in NMP 30% let
Mixture A was prepared by mixing and stirring 12 g of polyethersulfone (PES). On the other hand, 2 g of benzophenone (manufactured by Kanto Kagaku) as a photoinitiator and 0.2 g of Michler's ketone (manufactured by Kanto Kagaku) as a photosensitizer were heated to 40 ° C.
g of DMDG to prepare a mixture B. The liquid mixture A and the liquid mixture B were mixed and stirred to obtain a liquid resist composition.

(11) The liquid resist composition is applied on both sides of the substrate after the treatment for providing the catalyst nucleus in the above (9) using a roll coater, dried at 70 ° C. for 60 minutes, and dried with PES. The epoxy acrylate was phase-separated to form a 30 μm thick resin layer.

(12) A mask on which a pattern is drawn is laminated on the resin layer formed in the above (11), and is exposed by irradiating ultraviolet rays under the condition of 1000 mJ / cm ² , and then heated at 75 ° C. for 15 minutes. Processing was performed.

(13) The resin layer exposed in the above (12) is treated with DMTG
To form a plating resist on the substrate where the conductor circuit pattern has come off.
/ Cm ² , exposure at 100 ° C for 1 hour, then 150 ° C for 3 hours.
Heat treatment was performed for a long time to form a permanent resist 6 on the interlayer resin insulating layer.

(14) By spraying N-methylpyrrolidone (NMP) on the permanent resist 6 formed in (13),
By selectively dissolving and removing only the PES existing on the surface including the side wall of the permanent resist 6, the permanent resist 6 is removed.
Was roughened (see FIG. 1 (e)).

(15) On the substrate that has been subjected to the roughening treatment in (14),
Pre-plating treatment (specifically, sulfuric acid treatment and activation of catalyst nuclei) is performed in advance, and then the resist non-formed portion is formed by electroless plating using an electroless copper plating bath (primary plating bath, secondary plating bath). A conductor layer was formed by an additive method by depositing an electroless copper plating having a thickness of about 15 μm to form an outer layer copper pattern 7 and a via hole 8 (see FIG. 1 (f)).

(16) One side of the substrate on which the conductor layer was formed by the additive method in the above (15) was subjected to
The surface of the permanent resist and the uppermost surface of the conductive circuit including via holes were polished with a 600 belt abrasive paper until they were flush with each other. Next, buffing was performed to remove the scratches caused by the belt sander (polishing using only buffing may be performed). Such a series of polishing was similarly performed on the other surface of the substrate, thereby forming a printed substrate in which both surfaces of the substrate were flat (smooth).

(17) By repeating the above steps,
A conductor layer was further formed by the additive method.
Then, a multilayer printed wiring board having six layers was manufactured by building up the wiring layers in this manner (FIG. 1 (g)).
reference).

(Comparative Example) Basically the same as in Example, except that 50% of the epoxy groups of a cresol novolak type epoxy resin (trade name: EOCN-103S, manufactured by Nippon Kayaku) dissolved in DMDG were acrylated. Oligomers for imparting photosensitivity (molecular weight 4000), imidazole curing agent (trade name: 2E4MZ-CN, manufactured by Shikoku Chemicals), acrylic isocyanate that is a photosensitive monomer (trade name: Aronix M215, manufactured by Toagosei Co., Ltd.)
), Benzophenone as photoinitiator (Kanto Chemical), Michler's ketone as photosensitizer (Kanto Chemical)
Was mixed with NMP using the following composition, the viscosity was adjusted to 3000 cps with a homodisper stirrer, and then kneaded with three rolls to produce a multilayer printed wiring board. Resist composition; photosensitive epoxy / PES / M215 / BP /
MK / imidazole = 70/30/10/5 / 0.5 / 5 In this comparative example, the plating resist was not roughened.

The multilayer printed wiring boards manufactured in the above Examples and Comparative Examples were subjected to 2,000 heat cycle tests at -65 ° C. to 125 ° C. As a result, in the example, no cracks occurred in the upper and lower interlayer resin insulating layers in contact with the interface between the conductor circuit and the plating resist. On the other hand, in the comparative example, as shown in FIG. 2, cracks occurred in the upper and lower interlayer resin insulating layers in contact with the interface between the conductor circuit and the plating resist.

That is, when the conductor circuit is plastically deformed by polishing the wiring board, a projection as shown in FIGS. 2 and 3 is formed at the interface between the conductor circuit and the plating resist. According to the present invention, even when an interlayer resin insulating layer was further formed on the polished surface, it was confirmed by a heat cycle test that cracks did not occur in the interlayer resin insulating layer.

The printed wiring board (see FIG. 4) manufactured without polishing the surface of the wiring board on which the plating resist was formed was subjected to a heat cycle test.
It was confirmed that no cracks occurred in the interlayer resin insulation layer.

[0066]

As described above, according to the present invention, by using a resin composite comprising a thermoplastic resin and a photosensitive resin as a resin component constituting a plating resist for a printed wiring board, plating of the plating resist can be performed. Since the surface in contact with the conductor is roughened, it has not only excellent heat resistance and electrical characteristics, but also extremely excellent adhesion between the plating resist and the conductor circuit, and excellent reliability such as heat cycle characteristics. A printed wiring board can be provided.

[Brief description of the drawings]

FIG. 1 is a view showing one manufacturing process of a printed wiring board according to the present invention in an example.

FIG. 2 is an enlarged schematic cross-sectional view showing a state after a heat cycle test on a printed wiring board of a comparative example.

FIG. 3 is an enlarged schematic cross-sectional view showing a state after a heat cycle test on the printed wiring board of the example.

FIG. 4 is an enlarged schematic cross-sectional view showing a printed wiring board manufactured without polishing the surface of a wiring board on which a plating resist is formed in Examples.

[Explanation of symbols]

REFERENCE SIGNS LIST 1 substrate 2 inner layer copper pattern 3 insulating layer (interlayer resin insulating layer) 4 adhesive layer (interlayer resin insulating layer) 5 opening for via hole 6 plating resist (permanent resist) 7 outer layer copper pattern (conductor circuit via plating resist) ) 8 Via hole 9 Copper foil

Claims (7)

[Claims] 1. A printed wiring board comprising a conductive circuit provided on a surface of a resin insulating layer formed on a substrate via a plating resist in a portion where no plating resist is formed, wherein the plating resist is made of a thermoplastic resin and a photosensitive resin. A printed wiring board, characterized in that a resin composite comprising a resin is used as a resin component, and a side wall portion of the plating resist contacting a conductor circuit is roughened. 2. The printed wiring board according to claim 1, wherein the resin insulating layer is an adhesive layer for electroless plating. 3. The printed wiring board according to claim 1, wherein the surface of the plating resist is polished and smoothed so as to be flush with the surface of the conductor circuit. 4. A resin insulating layer is formed on a substrate, a plating resist is formed on a portion of the surface of the resin insulating layer other than the conductor pattern, and a conductive circuit formed by electroless plating is formed on a portion where the plating resist is not formed. In the method of manufacturing a printed wiring board to be formed, in forming the plating resist, a composition containing a mixed resin of a thermoplastic resin and a photosensitive resin as a resin component is applied to a substrate, dried, exposed, and developed. At the same time as hardening by curing, the surface including the side wall portion of the plating resist is treated with a solvent to dissolve and remove only the thermoplastic resin portion of the mixed resin to roughen the surface. Manufacturing method. 5. The method according to claim 4, wherein the resin insulating layer is formed using an adhesive for electroless plating. 6. The method according to claim 4, wherein a surface of the plating resist is polished and smoothed so as to be flush with a surface of the conductor circuit. 7. A plating resist composition comprising, as main components, an acrylate of a cresol novolac epoxy resin, an imidazole curing agent, and a thermoplastic resin.