JPH09252182A - Multilayered printed circuit board - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent a printed circuit board from generating a crack or peeling phenomenon, by controlling deterioration of heat resistance property and reliability of electric insulation property and by remarkably enhancing the physical stability. SOLUTION: In the printed wiring board comprising at least a first circuit pattern 2a formed on an insulated substrate 1, an insulation layer 3 coated on the first circuit pattern 2a and a second circuit pattern formed on the insulation layer 3, the coated insulation layer 3 is formed by dispersing phenoxy resin using the epoxy resin as the main element.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a multilayer printed wiring board.

[0002]

2. Description of the Related Art Generally, a printed wiring board used for various electric products has a multi-layer printing structure in which a circuit pattern is multi-layered with an increase in circuit density and an insulating layer is interposed therebetween. Wiring boards have been developed.

In the manufacturing process of a multilayer printed wiring board, the inner layer circuit pattern and the outer layer circuit pattern are separated and the insulating layer is
By a laminating method of laminating an insulating material on a pattern and a so-called build-up method of applying a molten insulating agent, electroless plating,
It plays a role of closely adhering the conductor, which will be a circuit pattern formed by electrolytic plating, and the insulating substrate.

A multilayer printed wiring board manufactured by a lamination method, in which an insulating material containing fibers serving as a skeleton such as kraft paper or glass fiber is laminated on an inner layer circuit pattern formed on a substrate, has a through hole and punching due to outer shape formation. Although a crack is generated by the stress acting on the processed part during the machining of, the kraft paper, the glass fiber and the like prevent the growth thereof, thereby preventing the quality problem.

[0005]

By the way, as one method for forming a multilayer printed wiring board, in a so-called build-up method of applying and adhering an insulating layer on the formed inner layer circuit pattern, a heat-resistant resin is generally used. Since the insulating layer is formed by applying a mixture of the synthetic rubber and synthetic rubber, there is no substance that forms the skeleton of the above-mentioned kraft paper, glass fiber, etc. It is fragile and easily cracks or peels off, and rubber components (acrylic rubber, silicone rubber) for imparting impact resistance not only lower the heat resistance and insulation reliability but also may peel off the insulating layer. There was a big problem in terms of quality.

[0006]

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and includes a first circuit pattern formed on an insulating substrate and an insulating layer applied on the first circuit pattern. And at least a second circuit pattern formed on the insulating layer, wherein the applied insulating layer has a phenoxy resin dispersed with at least one of epoxy, polyimide, and phenol resin as a main component. The present invention provides a multi-layer printed wiring board.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION An embodiment of a multilayer printed wiring board according to the present invention will be described in detail below with reference to FIG.

FIG. 1 shows a manufacturing process by a build-up method of a multilayer printed wiring board according to the present invention.
As shown in (A), conductor layers 2 and 2 to be inner layer circuit patterns are formed by pressure bonding (heating / pressurizing) on both surfaces of an insulating substrate 1 to be a base material. The conductor layer 2 is formed on at least one surface of the insulating substrate 1. At this time, since the crimped surfaces of the conductor layers 2 and 2 are formed with minute irregularities, the crimping of the both is favorably performed.

Then, a resist film is formed on the conductor layers 2 and 2, and the inner layer circuit pattern 2a is formed by exposing, developing and etching {FIG. 1 (B)}.

Then, the insulating layer 3 is applied and formed in the step of FIG. The insulating layer 3 contains a heat-resistant resin containing at least one of epoxy, polyimide, phenol resin, etc. as a main component, and a phenoxy resin and its modified product are added in place of the conventional rubber-based component.

The phenoxy resin and its modified products give a sea-island distribution in the resin. Since it is soluble in oxidizers such as chromic acid and permanganate used in the surface roughening process described later, it is a rough solution containing anchors resulting from the dissolution of the phenoxy resin and its modified products on the surface of the insulating layer. A surface is formed. Further, the phenoxy resin and its modified product have a function of enhancing flexibility, and can relax mechanical impact and mechanical / thermal stress like the rubber component. Further, the phenoxy resin is a thermoplastic but has a high molecular weight, has a glass transition point higher than that of a rubber-based elastomer by 30 ° C. or more, and improves heat resistance as an insulating layer. Furthermore, the phenoxy resin and its modified products have properties similar to those of the hard epoxy resin, and contribute to the improvement of electrical reliability.

As the composition of the insulating layer 3 in this embodiment, 100 parts by weight of bisphenol A type epoxy resin (made by Yuka Shell: E-1001) 30 parts by weight of phenol novolac type epoxy resin (made by Yuka Shell: E-154) 30 parts by weight Parts Phenoxy resin 10 parts by weight Imidazole curing agent (2P4MHZ manufactured by Shikoku Kasei) 20 parts by weight Barium sulfate 5 parts by weight Calcium carbonate (particles of 10 μm or less) 20 parts by weight.

In the step of FIG. 1D, the through holes 4 are formed by mechanical processing such as drilling. During this processing, the mechanical and thermal stress of the above-mentioned phenoxy resin and its modified material is relaxed. By the action, the physical strength of the insulating layer can be significantly increased, and cracks and peeling phenomena can be avoided.

[0014]

[Table 1]

Table 1 shows the conventional insulating layer mixed with rubber (Carboxy terminated butadiene acrylo as synthetic rubber).
nitrile copolymer) and the insulating layer in the example of the present invention are compared and shown, and the one in which the phenoxy resin is dispersed has a difference of one digit from the conventional one.

After that, the surface of the insulating layer 3 is roughened by a permanganate treatment solution to roughen the surface of the insulating layer 3 to about 5 μm, and then an outer layer conductor which becomes an outer layer circuit pattern is formed by plating as shown in FIG. 1 (E). 5 is formed.

Then, in the step of FIG. 1F, a resist film is formed on the conductor layers 5 and 5 in the same manner as the above-mentioned step, and exposed and developed to form the outer layer circuit pattern 5a,
5a and the through-hole conductor 5b are formed to finally obtain a multilayer printed wiring board formed in multiple layers.

[0018]

According to the multilayer printed wiring board according to the present invention described in detail above, the insulating layer formed by coating between circuit patterns has a physical strength significantly increased by dispersing the phenoxy resin and its modified product. The effect is that it can be increased, and cracks and peeling phenomena can be avoided.

[Brief description of drawings]

FIG. 1 is a manufacturing process diagram showing an embodiment of a multilayer printed wiring board according to the present invention.

[Explanation of symbols]

1 ... Insulating substrate, 2a ... Inner layer circuit pattern, 3 ... Insulating layer,
4 ... Through hole, 5a ... Outer layer circuit pattern.

[Procedure amendment]

[Submission date] July 9, 1996

[Procedure amendment 1]

[Document name to be amended] Statement

[Correction target item name] Name of invention

[Correction method] Change

[Correction contents]

Title of invention Multilayer printed wiring board

Claims (1)

[Claims] 1. At least a first circuit pattern formed on an insulating substrate, an insulating layer applied on the first circuit pattern, and a second circuit pattern formed on the insulating layer. In the printed wiring board described above, the applied insulating layer is a multilayer printed wiring board in which a phenoxy resin is dispersed with at least one of epoxy, polyimide, and phenol resin as a main component.