JPH03139897A - Manufacture of laminate sheet for printed circuit - Google Patents

Abstract

PURPOSE:To reduce warp and torsion due to strain at the time of molding by heating and pressurization by using glass nonwoven cloths having the different thickness and arranging prepreg having the different contents of inorganic filler with nonwoven clothes for molding by heating and pressurization. CONSTITUTION:In the constitution having a surface layer of glass woven cloths impregnated with varnish having epoxy resin as the main component while having an intermediate layer of the glass nonwoven cloths impregnated with varnish, in which aforesaid varnish contains inorganic filler, prepreg having a lot of the contents of inorganic filler using thick glass nonwoven cloths of 30 to 80g/cm<2> in weighing as the intermediate layer is arranged on the copper foil side, while prepreg having a lot of the contents of inorganic filler using thick glass nonwoven cloths of 100 to 200g/cm<2> in weighing is arranged on the opposite side in order to mold these surface layer and intermediate layer by heating and pressurization. Thereby, extension at the time of heating and pressurization is balanced with the thickness direction of flexibility deformation to curve up to the same level with a both side copper-clad laminated plate thus to improve the stability against torsion.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a method for manufacturing a single-sided copper-clad laminate that is less likely to warp or twist and has excellent dimensional stability.

[Conventional technology]

As laminates for printed circuits, there are a large number of laminates (hereinafter referred to as composite laminates) in which glass nonwoven fabric is used as an intermediate layer base material, glass woven fabric is used as a surface layer base material, and these base materials are impregnated with epoxy resin and heated and pressed. came to be used for.

Laminated boards made of glass woven fabric impregnated with epoxy resin have excellent mechanical strength, dimensional stability, heat resistance, etc., and are highly reliable through-hole plating, so they can be used in computers, communication equipment, and electronic exchange equipment. It is widely used in industrial electronic equipment such as 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 excellent mechanical performance such as bending strength and dimensional stability.

By the way, composite laminates generally use non-woven glass fabric as the base material for the intermediate layer, which is more prone to warping and twisting during hot-pressure molding than laminates using woven fabric base materials. It was said that the dimensional stability was poor. This problem is further amplified in a laminated board in which #R foil is laminated only on one side.

[Problem to be solved by the invention]

The present invention aims to reduce the warping and twisting of single-sided copper-clad laminates due to distortion during hot-pressure forming to the same extent as double-sided steel-clad laminates, without losing the excellent features of composite laminates. do.

[Means to solve the problem]

The present invention has a structure in which the surface layer is a glass woven fabric impregnated with a varnish containing an epoxy resin as a main component, and the intermediate layer is a glass nonwoven fabric impregnated with a varnish containing a non-AT filler. This is a method for producing a printed circuit laminate using a glass nonwoven fabric, which is characterized in that prepregs having different inorganic filler contents are arranged on the nonwoven fabric of the parentheses and then molded under heat and pressure.

In the present invention, preferably, the surface layer is made of a glass woven fabric impregnated with a varnish containing bisphenol A type epoxy resin and novolak type epoxy resin as the epoxy resin components, and the intermediate layer is preferably made of a glass woven fabric impregnated with a varnish mainly composed of the same resin as the surface layer. A laminate for printed circuits comprising several types of glass nonwoven fabric substrates of different thicknesses in which a varnish is impregnated with an epoxy resin containing an inorganic filler, and the surface layer and the intermediate layer are heated and pressurized. This is a method of manufacturing a board.

The bisphenol A type epoxy resin used in the present invention is suitably one having an i of 1,700 to 1,200 based on epoxy. Laminated boards using low-molecular-weight epoxy resins cannot absorb mechanical and thermal shocks during the processing process, which often leads to breakage. Therefore, the molecular weight of the epoxy resin used is increased, and epoxy equivalents of 700 or more are used. When used, the molecular weight between the crosslinking points becomes larger than before, and the mechanical and thermal shock during processing described above is absorbed as molecular movement, making it difficult for the laminate to break. On the other hand, when the molecular weight of bisphenol A type epoxy resin is increased, the viscosity does not decrease even when heated during pressure molding, and the resin is difficult to penetrate into the interface with glass fibers and metal foil, leaving air bubbles that reduce adhesive strength. Lower it.

Therefore, the decrease in crosslinking density due to increase in molecular weight can be suppressed by using a novolac type epoxy resin in combination. When this novolac type epoxy resin is used in combination, a bisphenol A type epoxy resin having an epoxy equivalent of 1200 or less can be used. If an epoxy resin with a higher molecular weight than this is used, even if a novolak type epoxy resin is used in combination, the result will be poor in terms of practicality such as solvent resistance.

In the present invention, a brominated bisphenol epoxy resin is usually used, and the bromine content is 15 to 30% (
% by weight (the same applies hereinafter) is preferred.

In addition, the blending ratio with bisphenol A type epoxy resin is not particularly limited, but bisphenol A type epoxy resin 6
0 to 90 parts of novolac type epoxy resin 40-10
In the present invention, even if a part of the bisphenol A epoxy resin having an epoxy equivalent of 700 to 1,200 is replaced with an epoxy compound having a lower epoxy equivalent than this, the dimensions, warping, and torsion that are the objectives of the present invention cannot be achieved. Effective for stability.

The amount of inorganic filler in the intermediate layer used in the present invention is preferably 10 to 200%, particularly preferably 40% to the resin.
~200% included.

If it is less than 10%, the effect of improving heat resistance will be small, and if it is more than 200%, the resin viscosity during mixing will become too high, making it difficult to impregnate the glass nonwoven fabric base material. If it is less than 40%, the dimensional stability and reliability of through-hole plating deteriorates, which is not preferable.

Particularly preferably, it is 40-80% on the copper foil side, 170-200% on the opposite side, and 90-20% if there is a layer between these.
Prepregs containing 160 parts of inorganic filler are obtained. The glass nonwoven fabric at this time was also 30% on the copper foil side.
A thin one with a basis weight of ~80g/nf, and 10g/nf on the other side.
Use a thick one with a basis weight of 0 to 200 g/rrf. If there is an intermediate layer, either one may be used, or one having a basis weight between the two may be used.

Next, a prepreg made by impregnating this glass non-woven fabric base material with epoxy resin varnishes having different contents of inorganic fillers is used as an intermediate layer, an epoxy resin-impregnated glass woven fabric is placed on the surface layer, and copper foil is further layered and heated. By pressing and integrating, a printed circuit laminate according to the present invention is obtained.

[For production]

Since conventional composite laminates use glass nonwoven fabric as the base material of the intermediate layer, they are said to be inferior in warpage, twisting, and dimensional stability compared to laminates with glass woven fabric base materials. In particular, in a configuration in which copper foil is laminated only on one side, the problem is amplified even further when balancing the elongation and shrinkage deformation in the thickness direction. Torsional stability can be improved.

〔Example〕

The composition of the epoxy resin varnish is as follows.

Part 1 table The materials were mixed to produce a uniform varnish.

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 having a composition shown in Table 2 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.

This inorganic filler-containing varnish was impregnated into a glass nonwoven fabric substrate having the basis weight shown in Table 2 so that the content of resin and inorganic filler was 90% and dried to obtain a prepreg.

(Unit 2 parts) A structure in which the glass woven fabric prepreg is arranged on the upper and lower surface layers and the glass nonwoven fabric base material prepreg is used as the intermediate layer, and prepreg A and prepreg C are arranged as the combination of the intermediate layer (Example 1), In addition to prepreg A and prepreg B (Example 2), prepreg B or C
Layer 35μm thick W4 foil only on the side surface, and molding temperature 1.
Lamination molding was carried out at 65° C. and a pressure of 60 kg/cii for 90 minutes to obtain a copper-clad laminate having a thickness of 1.6 m.

Comparative Example The thickness was 1.6 in the same manner as in Example 1.2 except that the intermediate layer in the above Example was composed of prepreg A alone.
A laminate of wa was obtained.

The warpage of the obtained copper-clad laminate was measured.

The results are shown in Table 3.

The warpage was measured on a copper-clad laminate cut to a size of 30 x 30 cm, subjected to various treatments, and then placed on a flat plate.
It was determined by the highest value of the height.

Warpage of copper-clad laminate (unit: m) As is clear from Table 2, it can be seen that the copper-clad laminate according to Example 1.2 has an excellent effect in suppressing the occurrence of warpage.

〔Effect of the invention〕

By arranging it on the side of the laminate, it is possible to suppress distortion during hot-pressure molding, so warping is significantly reduced compared to conventional composite laminates that uniformly contain inorganic filler, and it is equivalent to double-sided copper-clad laminates. level, and is suitable as a manufacturing method for industrial printed circuit laminates.

Claims (1)

[Claims] (1) In a structure in which the surface layer is a glass woven fabric impregnated with a varnish containing an epoxy resin as a main component, and the intermediate layer is a glass nonwoven fabric impregnated with a varnish containing an inorganic filler, the intermediate layer has a basis weight of 30. ~80g/cm^
A prepreg with a low content of inorganic filler using thin glass nonwoven fabric of No. 2 is placed on the copper foil side, and the basis weight is 100 to 2.
Single-sided copper for printed circuits, characterized in that a prepreg with a high content of inorganic filler using a thick glass non-woven fabric of 00g/cm^2 is arranged on the opposite side, and the surface layer and the intermediate layer are heated and press-molded. Method for manufacturing tension laminates.