JPH0429391A - Manufacture of laminated plate for printed circuit - Google Patents

Abstract

PURPOSE:To improve heat resistance of an obtained laminated plate by using aluminum hydroxide not processed through a pulverizing step as a filler in a manufacturing step. CONSTITUTION:Aluminum hydroxide not processed through a pulverizing step is used as a laminated plate in which a surface layer is made of thermosetting resin-immersed glass woven cloth, and an intermediate layer is formed of glass nonwoven fabric immersed with varnish using aluminum hydroxide as a filler in thermosetting resin. That is, high temperature of starting temperature of decomposition due to heat absorption of the aluminum hydroxide is aimed at. Thus, the heat resistance of the plate can be set equivalently to that of the plate using other filler.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a method for manufacturing a printed circuit laminate that has excellent heat resistance, contains few ionic impurities, and has low conductivity.

(Prior art) As a laminate for one-way printing, a laminate (hereinafter referred to as composite laminates) have come into widespread use.

Laminated boards made of woven glass fabric impregnated with epoxy resin have excellent mechanical strength, dimensional stability, heat resistance, etc., and have high reliability in through-hole plating, so they can be used in computers, communications equipment, electronic switching equipment, etc. It is widely used in industrial equipment. However, since only glass woven fabric is used as the base material, punching is not possible in the drilling process, which is one of the processing steps for printed circuit boards, and the reality is that drilling is required.

On the other hand, composite laminates are economically cheaper than woven glass fabric laminates and have the advantage of being able to be punched and punched, and have attracted attention as glass-based laminates with good workability. The reliability of through-hole plating was evaluated to be lower than that of glass woven fabric base laminates. The reason for this is that the composition of the glass woven fabric base epoxy laminate is such that the weight ratio of the organic epoxy resin to the inorganic glass woven fabric is about 40:60. In this case, it is thought that the epoxy resin mainly provides excellent electrical performance, and the glass woven fabric provides good mechanical performance such as bending strength and dimensional stability.

General composite laminates use glass nonwoven fabric as the base material for the intermediate layer, so the weight ratio of epoxy resin and inorganic materials is approximately 60 + 40, which is the opposite ratio to that of glass woven fabric laminates, and the reliability of through-hole plating. was rated as having low gender. In order to improve these drawbacks, by incorporating a large amount of inorganic filler and increasing the ratio of inorganic substances in the composite laminate, it is possible to improve the reliability of through-hole plating to the same level or higher than that of glass woven fabric laminates.

Inorganic fillers that can be used include clay, talc, mica, silica powder, alumina, aluminum hydroxide, glass powder, titanium white, wollastonite, etc. Among these, aluminum hydroxide is effective for improving heat resistance. It is effective, has few ionic impurities, and has excellent insulation properties, which are features not found in other fillers. However, on the other hand, it has the problem of inferior heat resistance compared to other fillers.

(Problems to be Solved by the Invention) The present invention improves the heat resistance of a laminate using aluminum hydroxide, which is optimal as an insulating inorganic filler, without losing the excellent features of conventional composite laminates. The aim is to make the heat resistance equivalent to that of laminates using fillers.

(Means for Solving the Problems) In the present invention, the surface layer is made of a glass woven fabric impregnated with a thermosetting resin, and the intermediate layer is made of a glass nonwoven fabric impregnated with a varnish in which the thermosetting resin is impregnated with aluminum hydroxide as a filler. This is a method for manufacturing a laminate for printed circuits, characterized in that aluminum hydroxide that does not go through a pulverization process is used in the laminate.

When aluminum hydroxide was used as a filler in conventional composite laminates, there was a problem in that the heat resistance was poor.

This is because aluminum hydroxide begins to decompose at around 210°C due to heat absorption and releases water.

The powdered aluminum hydroxide currently in use is obtained from hawkide and caustic soda as raw materials, by precipitating aluminum hydroxide from a slurry state, filtering and washing, drying, and pulverizing to adjust the particle size.

Silica, wollastonite, alumina, glass powder, talc, etc. are used to compensate for the above drawbacks, but they suffer from poor workability in terms of hardness and poor moisture absorption and insulation properties due to ionic impurities. There is.

The present invention focuses on increasing the start temperature of decomposition due to endothermic action of aluminum hydroxide. As mentioned above, conventional aluminum hydroxide undergoes a pulverization process for particle size adjustment, which destroys the crystal structure of aluminum hydroxide and facilitates release of water.

By paying attention to this and using aluminum hydroxide which does not go through the pulverization process during the manufacturing process, it is possible to improve the heat resistance to the same level as the other fillers mentioned above. In this case, the average particle size is 5 to 10 μm, and the maximum particle size is 40 μm.
m or less is desirable.

(Example) The composition of the epoxy resin varnish is shown in Table 1.

Table 1 A uniform varnish was prepared by mixing the above materials.

Next, the varnish blended for the surface layer was applied to a glass woven fabric (Nittobo WE-18-RB84) with a resin content of 42 to
It was impregnated and dried to a concentration of 45% to obtain a glass woven prepreg.

Subsequently, an inorganic filler of the following formulation was added to 100 parts of resin to a varnish similarly formulated for the intermediate layer, and the mixture was stirred and mixed to prepare an inorganic filler-containing varnish.

95 parts of aluminum hydroxide (average particle size 5 to 10 μm) that does not undergo a pulverization process 5 parts of ultrafine powdered silica (Carplex, manufactured by Geotsugi Pharmaceutical Co., Ltd.) This inorganic filler-containing varnish is applied to a glass nonwoven fabric base material (manufactured by Nippon Vilene) with resin and A prepreg was obtained by impregnation and drying so that the inorganic filler content was 90%.

A glass non-woven fabric base material prepreg is used as an intermediate layer, the glass woven fabric prepreg is placed on the upper and lower surface layers, metal foil is further layered on top of that, and the molding temperature is +65°C, 1 pressure cuff 0 kg/
Lamination molding was carried out for 90 minutes using ALF to obtain a 1.6-thick copper-clad laminate.

(Comparative Example) A copper-clad laminate having a thickness of 1.6 mm was obtained in the same manner as in the above Example, except that aluminum hydroxide that had undergone a conventional pulverization process was blended.

The solder heat resistance and reflow solder heat resistance of the obtained copper-clad M-layer board were comparatively measured. The results are shown in Table 2.

Table 2 (Note) Soldering heat resistance: Time until blistering occurs Reflow soldering heat resistance: Number of treatments until blistering occurs As is clear from the results in Table 2, aluminum hydroxide that does not go through the pulverization process has a crystalline structure. Since it is stronger, decomposition is less likely to occur and the temperature at which water is released becomes higher, improving the heat resistance of the laminate.

(Effects of the Invention) According to the present invention, aluminum hydroxide, which does not go through the pulverization process, is used as a filler in the manufacturing process, so the heat resistance of the obtained laminate has been greatly improved. Since it is fully compatible with surface mounting technology, it can be applied to applications in fields where only glass-based laminates have traditionally been used.

Claims (1)

[Claims] (1) The surface layer is made of a glass woven fabric impregnated with a thermosetting resin, and the intermediate layer is made of a glass nonwoven fabric impregnated with a resin containing 10 to 200% by weight of aluminum hydroxide based on the thermosetting resin. A method for manufacturing a laminate for printed circuits, wherein the aluminum hydroxide does not undergo a pulverization step in the manufacturing process.