JPS6336623B2 - - Google Patents

Description

[Detailed description of the invention]

[Technical Field] The present invention relates to a method for manufacturing a multilayer board in which an inner layer material and an outer layer material are bonded together with prepreg, and particularly to a method for manufacturing a substrate for a printed wiring board. [Background technology] Prepreg is manufactured by impregnating a base material such as glass cloth with resin varnish and drying it. However, when polyimide resin varnish is used as the resin varnish for manufacturing prepreg, polycondensation type polyimide When a resin varnish is used, there is a problem in that water is released during hot molding and reduces adhesive strength, so addition polymerization type polyimide resin varnish has traditionally been used. However, even when a prepreg manufactured using this addition polymerization type resin varnish is laminated and molded with an outer layer material such as copper foil or an inner layer material, there is still a drawback that the adhesion between the inner and outer layer materials is insufficient. [Object of the Invention] The present invention has been made in view of the above points, and an object of the present invention is to provide a method for manufacturing a multilayer board that can improve interlayer adhesion. [Disclosure of the Invention] That is, the present invention impregnates a base material with a polycondensation type polyimide resin varnish and dries it, then impregnates and dries an addition polymerization type polyimide resin varnish to create a prepreg, and uses this prepreg as an inner layer. The above object has been achieved by a method for producing a multilayer board, which is characterized by laminating and forming layers between a material and an outer layer material. The present invention will be explained in detail below. Polycondensation type polyimide resin varnishes generally have good moldability and produce products with good dimensional accuracy, and also have characteristics such as good adhesion to copper foil and good water resistance. However, since water is released by reaction during molding, there is a drawback that water is present on the adhesive surface with the copper foil, reducing the adhesiveness. Examples of commercially available polycondensation type polyimide resin varnishes include:
Torlon (Amco), Pyflon (Hitachi Chemical Co., Ltd.)
Ltd.), Umtel (G.E. Ltd.), polyimide (Japan Synthetic Rubber Co., Ltd.), etc. Moreover, as the addition polymerization type polyimide resin varnish, those conventionally used can be used. In producing prepreg, a base material such as glass cloth or paper is impregnated with the polycondensation type resin varnish and dried. In this case, the amount of resin is preferably 3 to 25%, and the volatile content is preferably 3% or less. Next, this material is further impregnated with an addition polymerization type resin varnish and dried to create a prepreg. The total resin content of this prepreg is preferably about 50%, and the volatile content is preferably about 3% or less. The thus prepared prepreg is laminated between an inner layer material made of copper foil or the like and an outer layer material, and this laminate is laminated and molded to obtain a multilayer board. By impregnating the base material with polycondensation type resin varnish and drying it, moldability, adhesion,
In addition to being able to improve water resistance, heating and drying promotes the reaction of the polycondensation type resin and evaporates water released by the condensation reaction. In particular, polycondensation type polyimide resin varnish has low viscosity and high reactivity, so it can be sufficiently impregnated into the base material, and it can react with the surface treatment agent of the base material, so it has cohesive strength. In addition, when this resin varnish is used, dimensional accuracy is good and moldability can be improved. Next, by impregnating and drying this material with an addition polymerization type resin varnish, the adhesive strength between the outer layer material, the inner layer material, and the prepreg is increased without the presence of water between the outer layer material, the inner layer material, and the prepreg. It is something that can be glued. The present invention will be specifically described below based on Examples. <Example> Polycondensation type polyimide resin varnish (manufactured by Japan Synthetic Rubber Co., Ltd., polyimide) was impregnated into a 0.1 mm thick glass cloth and dried to obtain a prepreg with a resin content of 20% and a volatile content of 2.0%. was impregnated into an addition polymerization type polyimide resin varnish and dried to obtain a prepreg with a total resin content of 55% and a volatile content of 2.0%. Next, a 1 mm thick sheet with electrical circuits formed on both sides.
The above prepreg was laminated one by one on the top and bottom surfaces of the inner layer material, and then a single-sided copper-clad polyimide laminate with a thickness of 1.0 mm was laminated on both the top and bottom of the above prepreg with the copper foil side facing the outermost side, and molded. Pressure 40Kg/ ^cm2・
Lamination molding was performed at 165° C. for 20 minutes to obtain a multilayer board with a four-layer circuit. <Conventional example> Example except that a prepreg with a resin content of 55% and a volatile content of 2.0% obtained by impregnating and drying a 0.1 mm thick glass cloth with only the addition polymerization type polyimide resin varnish used in the example was used. A multilayer board was obtained by lamination molding in the same manner as above. Next, the peeling strength of the inner layer materials of the multilayer boards obtained in Examples and Conventional Examples was measured. The results are shown below.

〔Effect of the invention〕

As described above, the present invention involves impregnating and drying a base material with a polycondensation type polyimide resin varnish, then impregnating and drying an addition polymerization type polyimide resin varnish to create a prepreg, and combining this prepreg with an inner layer material and an outer layer material. Since it is laminated and formed between the polycondensation type resin varnish and the polycondensation type resin varnish, the adhesive strength does not decrease due to the water released during the reaction of the polycondensation type resin varnish, making it possible to manufacture multilayer boards with excellent interlayer adhesive strength. It is possible.

Claims (1)

[Claims] 1 The base material is impregnated with a polycondensation type polyimide resin varnish and dried, then an addition polymerization type polyimide resin varnish is impregnated and dried to create a prepreg, and this prepreg is laminated between the inner layer material and the outer layer material. A method for manufacturing a multilayer board, characterized by carrying out lamination molding.