JPH09307232A - Printed wiring board and manufacturing method thereof - Google Patents

Abstract

(57) Abstract: A step of stacking a synthetic resin sheet on a main surface of a supporting substrate on which a group of conductor bumps is formed in contact with each other, and stacking the synthetic resin sheet on the laminate. Primary heating and pressurizing the arranged ones to pierce and expose the tip of the bump group in the thickness direction of the synthetic resin sheet, and a step of piercing and exposing the tip of the conductor bump group and laminating a conductive metal foil on the exposed surface. And a laminated body in which the conductive metal foils are laminated and arranged.
Next, a step of applying pressure to connect the tip of the bump group to the surface of the conductive metal foil by plastic deformation to form a through-type conductor wiring portion; and a conductive metal foil of a laminated body on which the through-type conductor wiring portion is formed. In a method for manufacturing a printed wiring board including a step of forming a pattern for connecting to the through-type conductor wiring portion by etching, the hardness of the tip end portion of the conductor bump is softer than the hardness of the conductor bump on the supporting base side. A method for manufacturing a printed wiring board, which is characterized in that it has a configuration. [Effect] Simplifies the manufacturing process of printed wiring boards,
A printed wiring board having high connection reliability and a method for manufacturing the same can be provided.

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 and a method for manufacturing the same, and in particular, it has a structure in which wiring layers are connected by a penetrating conductor wiring portion and enables high-density wiring and mounting. A highly reliable printed wiring board is provided, and the manufacturing method thereof is a method which can be manufactured reasonably with a good yield.

[0002]

2. Description of the Related Art In a two-layer or multi-layer printed wiring board, electrical connection between wiring layers such as double-sided conductive patterns is required.
It is done as follows. That is, in a two-layer printed wiring board, perforation is performed at a predetermined position of a double-sided copper-clad laminate, and electroless and electrolytic plating treatments are performed on the entire surface including the inside of the hole to thicken the metal layer on the inner wall surface of the hole to ensure continuity. The electrical connection between wiring layers with improved reliability is performed. In the case of a multilayer printed wiring board, after patterning the copper foils stretched on both sides of the substrate, copper foils are laminated and arranged on the pattern surfaces via an insulating sheet, and integrated by heating and pressing. After that, similarly to the above-mentioned two-layer printed wiring board, electrical connection between wiring layers by punching and plating and patterning of the surface copper foil are performed to obtain a multilayer printed wiring board. In the production of the printed wiring board, as a means for electrically connecting the wiring layers without using a plating method, a hole is made at a predetermined position of the double-sided copper-clad laminate, and a conductive paste or the like is poured into the hole and cured. A method of electrically connecting wiring layers has also been performed.

[0003]

As described above, in a method of manufacturing a printed wiring board using a plating method for electrical connection between wiring layers, a copper clad laminate is punched for electrical connection between wiring layers. However, there is a drawback in that a plating process including the inner wall of the hole is required and the manufacturing process of the printed wiring board is complicated. On the other hand, a method of embedding a conductive paste in a hole for electrical connection between wiring layers by printing or the like also requires a hole forming step as in the case of the plating method. Moreover, it is particularly difficult to pour the conductive paste or the like into the holes even if the hole diameter is small, and there is a problem in reliability. In either case,
The necessity of the perforating step is reflected in the cost and yield of the printed wiring board, and there is a drawback that the demand for cost reduction cannot be met.

Further, according to the above-mentioned conventional method, since conductor holes for connecting wiring layers are provided on the front and back surfaces of the printed wiring board, wiring cannot be formed and components cannot be mounted in that area. There is a problem that the improvement of the density is restricted and the improvement of the mounting density of components is also hindered. With the miniaturization and weight reduction of electronic devices, high density wiring of printed wiring boards by the conventional method,
It cannot be said that high-density mounting is sufficient, and a more effective printed wiring board and its manufacturing method are desired. The present invention has been made to address these situations,
It is a reliable printed wiring board capable of high-density wiring and mounting by a simple process, and is a method of manufacturing this with a high yield.

[0005]

According to the present invention, there is provided a step of placing a synthetic resin sheet on a main surface of a supporting substrate having a group of conductor bumps formed at predetermined positions so as to be in contact with each other, and laminating the synthetic resin sheet. Primary heating and pressurizing of the stacked sheets arranged to penetrate and expose the tip of the bump group in the thickness direction of the synthetic resin sheet, and a conductive metal foil is laminated on the penetrated and exposed surface of the tip of the conductor bump group. A step of arranging, and a step of secondarily pressing the laminated body in which the conductive metal foils are laminated and connecting the tip of the bump group to the surface of the conductive metal foil by plastic deformation to form a through conductor wiring portion. In the method for manufacturing a printed wiring board, including the step of forming a pattern for connecting to the through-type conductor wiring portion by etching on the conductive metal foil of the laminated body on which the through-type conductor wiring portion is formed, Tip of bump Hardness parts is a method for manufacturing a printed wiring board, characterized in that a softer structure than the hardness of the support base side of the conductor bump. Further, the present invention provides a conductor bump group formed on a supporting base, wherein the hardness of the supporting base side of the conductor bump is different from the hardness of the tip part, and the conductor bump group is formed on the supporting base having a softer tip part. Is. Further, the present invention provides a conductor bump group formed on a supporting base, wherein the hardness of the supporting base side of the conductor bump is different from the hardness of the tip end of the conductor bump group, and the tip end is softer. This is the printed wiring board used.

[0006]

BEST MODE FOR CARRYING OUT THE INVENTION In the present invention, the supporting substrate forming the conductor bump group includes, for example, a synthetic resin sheet or a conductive sheet (foil) having good peelability. This supporting substrate is
It may be a single sheet or a patterned sheet and is not particularly limited.

In the present invention, the conductor bump group may be formed not only on one main surface of the support substrate but also on both main surfaces.

In the present invention, the conductor bump can penetrate through the synthetic resin sheet or the like at the heating and pressurizing state in which the resin content of the synthetic resin sheet is in the plastic state or above the glass transition temperature, that is, the primary pressurizing step. It has a certain degree of hardness, and is configured such that the hardness of the tip of the conductor bump is softer than the hardness of the conductor bump on the side of the support base so that the tip is easily plastically deformed in the secondary pressing stage.

In the present invention, the method of making the hardness of the tip end of the conductor bump different from the hardness of the supporting substrate side is, for example, to prepare a bump forming composition having different hardness after curing, and the hardness of the supporting substrate side is high. One with a low hardness is placed on the tip side, or the heating time of the portion of the conductor bump on the side of the supporting base is increased so that the curing degree is different even if the same composition is used. There are ways. By adopting such a structure in the conductor bump, the connection reliability between the conductor bump and the conductive metal foil to be connected in the secondary pressurization becomes higher, and the shape of the portion embedded in the synthetic resin sheet is improved. Deformation can be minimized, which is effective for forming a high-density wiring board.

In the present invention, the conductor bumps are silver, gold,
It is composed of a conductive composition such as copper, solder or the like, an alloy or a mixed powder thereof, and a binder composition such as a polyimide resin, a phenol resin or a polyester resin, or a conductive metal, or the like.

In the present invention, the conductive bumps are formed by a printing method using a relatively thick metal mask, and the number of times of printing is two or more because the composition is different. The height of the conductor bump is not particularly limited, but is generally about 0.1 to 0.4 mm.

In the present invention, the synthetic resin sheet for penetrating the conductor bump group and forming the penetrating conductor wiring portion is, for example, a thermoplastic sheet and has a thickness of 0.05 to
0.8 mm is common. Here, examples of the thermoplastic sheet include polycarbonate resin, thermoplastic polyimide resin, and polyether ether ketone resin.
The B-stage thermosetting resin sheet includes epoxy resin, polyimide resin, phenol resin, bismaleimide triazine resin and the like. These synthetic resins may be used alone or may contain an insulating inorganic material or an organic filler, and are a prepreg-based sheet formed by combining with a reinforcing material such as glass cloth, mat, organic synthetic fiber cloth or mat, or paper. May be.

In the present invention, the shape of the conductor bump group formed on the supporting substrate is not particularly limited, and examples thereof include a conical shape as shown in FIG.

In the present invention, in the primary pressing step, a roller made of heatable metal, heat-resistant resin, ceramics, etc., and a roller which elastically deforms when pressed, for example, made of rubber such as butadiene or neoprene, A method of passing between rollers made of polytetrafluoroethylene resin or the like is preferable.

In the present invention, when the pressed body is arranged on the synthetic resin sheet side (the side opposite to the supporting substrate on which the conductor bump group is formed) in the primary pressurizing step, the tip of the conductor bump group can be more easily and securely formed. It is possible to penetrate the synthetic resin sheet. The material is not particularly limited, but for example, a silicon film or the like is used.

In the present invention, it is general to use a hydraulic type multi-stage vacuum press or an autoclave type fresh air press in the secondary pressurizing step.

According to the method for manufacturing a printed wiring board of the present invention, the conductor wiring portion between the layers for electrically connecting the wiring layers is
By the first pressurization in the so-called laminated integration process, first, the tip of the conductor bump penetrates the predetermined position of the synthetic resin sheet forming the interlayer insulating layer with high accuracy and certainty, and the second pressurization causes the above-mentioned composite press. Plastic deformation easily occurs due to plasticization of the resin-based sheet and pressure contact of the tip of the conductor bump to the conductive metal foil surface, and reliable lamination integration and reliable electrical connection between wiring layers are achieved. . That is, by simplifying the process, it is possible to form a highly accurate and reliable electrical connection between fine wiring layers at arbitrary positions, and it is possible to manufacture a high-density printed wiring board at low cost. Become. Further, it is not necessary to form a connection hole for electrical connection between the wiring layers, and accordingly, high-density wiring and high-density mounting can be realized.

[0018]

EXAMPLES Examples will be described below with reference to the drawings. 0.
A silver paste (hardness after curing: Brin) using 018 mm electrolytic copper foil as a support substrate 1 and polyimide as a binder
ell hardness 43) is printed on the roughened surface of the copper foil using a metal mask, and after curing, a silver paste using polyimide as a binder (hardness after curing: Brinell hardness 35) is printed using the metal mask. The conductor bumps 2 were formed by curing (FIG. 1). The conductor bump 2 is hard on the support base side and soft on the tip end.

On the other hand, a polyetherimide resin sheet having a thickness of 0.15 mm is prepared as the synthetic resin sheet 3,
A primary pressure was passed through a roller composed of a metallic roller and a flexible rubber roller, which were opposed to the formed conductor bump and heated to 250 ° C. (FIG. 2). Next, a 0.018 mm electrolytic copper foil (conductive metal foil) 4 is placed on the penetrating surface of the conductor bump, a contact plate 5 is placed (FIG. 3), and a hydraulic press 27
Secondary pressure was applied at 0 ° C. and 50 kg / cm ² for 60 minutes. As a result, a double-sided copper clad laminate for a printed wiring board having a conductor wiring portion 6 penetrating was obtained (FIG. 4). Conductor circuits were formed on these surfaces by an etching method to obtain a two-layer printed wiring board. An electrical inspection, which is usually performed by inspecting a printed wiring board, was applied to this, but there was no problem in electrical connection, and there was no problem in reliability in a solder heat resistance test at 288 ° C. for 60 seconds.

[0020]

According to the present invention, it is possible to provide a two-layer printed wiring board or a multilayer printed wiring board having high connection reliability and a manufacturing method thereof while simplifying the manufacturing process of the printed wiring board. In particular, in the case of a multi-layer printed wiring board having a long process, the process is greatly simplified and the effect on the factory of productivity is great. Then, the hole-drilling plating step in the conventional method is not necessary, and defects occurring in the manufacturing process can be reduced.
Further, since the printed wiring board of the present invention has no interlayer connection hole,
The wiring density can be remarkably improved, and the component mounting density can also be expected to be improved.

[Brief description of drawings]

FIG. 1 is a sectional view showing a stage in which a conductor bump group is formed on a supporting base.

FIG. 2 is a view showing that a synthetic resin sheet is placed on a supporting substrate having a conductor bump group formed in FIG. Sectional view showing steps

FIG. 3 is a diagram in which the synthetic resin sheet formed in FIG. 2 and the supporting base having the conductor bump group are primarily pressed, but a conductive metal foil is arranged on the surface through which the bumps penetrate, and a pressing plate is arranged and the second pressing is performed. Sectional view of the stage

FIG. 4 is a cross-sectional view of a laminated board having through conductor wiring portions formed by secondarily pressing the one in the stage of FIG.

FIG. 5 is a cross-sectional view of conductor bumps having different hardnesses formed on a support base.

[Explanation of symbols]

 1 Support Base 2 Conductive Bump 3 Synthetic Resin Sheet 4 Conductive Metal Foil 5 Contact Plate 6 Conductor Wiring Part 7 Penetrating Conductor Bump Tip (Softer than Part 8) 8 Conductor Bump Support Base Side (from Part 7) hard)

Claims (3)

[Claims] 1. A step of laminating and placing a synthetic resin sheet on a main surface of a supporting substrate on which a group of conductor bumps are formed at predetermined positions, and a step of laminating a synthetic resin sheet on the laminated body. Next, heating and pressurizing to penetrate and expose the tip of the bump group in the thickness direction of the synthetic resin sheet; piercing the tip of the conductor bump group and placing a conductive metal foil on the exposed surface; 2 layers of laminated metal foil
Next, a step of applying pressure to connect the tip of the bump group to the surface of the conductive metal foil by plastic deformation to form a through-type conductor wiring portion; and a conductive metal foil of a laminated body on which the through-type conductor wiring portion is formed. In a method for manufacturing a printed wiring board including a step of forming a pattern for connecting to the through-type conductor wiring portion by etching, the hardness of the tip end portion of the conductor bump is softer than the hardness of the conductor bump on the supporting base side. A method for manufacturing a printed wiring board, which is characterized in that it has a configuration. 2. A conductor bump group formed on a supporting base, wherein the hardness of the supporting base side of the conductor bump is different from the hardness of the tip end of the conductor bump, and the tip end is softer. 3. A conductor bump group formed on a support base, wherein the conductor bump group formed on a support base is such that the hardness of the support base side of the conductor bump is different from the hardness of the tip part, and the tip part is softer. Printed wiring board used.