JPH0470991B2 - - Google Patents

Description

[Detailed description of the invention]

INDUSTRIAL APPLICATION FIELD The present invention relates to a method for manufacturing a laminate with little dimensional shrinkage during processing steps such as printed circuit board manufacturing. Conventional technology As is well known, laminates are made by piling up the necessary number of prepregs made by impregnating and drying a base material such as paper, glass cloth, cloth, etc. with thermosetting resin to form a B stage, and if necessary, adding copper foil to one side. Alternatively, it is manufactured by stacking the two sides together, sandwiching them between stainless steel plates, applying heat and pressure to harden the resin, and then cooling under pressure to at least 100 degrees Celsius or less, below the glass transition temperature of the resin, and then dismantling it. . Problems to be Solved by the Invention However, in the conventional method of sandwiching prepreg between stainless steel plates and molding, the free movement of thermal contraction during cooling of the resin is regulated by the molding pressure. In addition, since the stainless steel plate and copper foil or mold release polymer film (acetate film, etc.) are always in contact with each other, the resin that is in contact with them on the inside is subject to heat shrinkage due to friction with the stainless steel plate. Movement is regulated. As a result, dimensional shrinkage of the laminate occurs during processing steps such as printed circuit board manufacturing, and positional displacement of circuits occurs during circuit processing steps. The present invention provides a method for manufacturing a laminate in which dimensional shrinkage during the processing steps as described above is suppressed. Means for Solving the Problems In order to solve these problems, the present invention was developed as a result of studies, and in order to avoid the influence of the stainless steel plates, the formed laminates are disassembled while they are still hot, and at least We have discovered that it is possible to produce a laminate with low dimensional shrinkage by disassembling the resin at a temperature above the glass transition temperature (Tg) of the cured resin. Function: Since the thermosetting resin is disassembled at a high temperature during the cooling process after curing, the pressure applied during cooling of the disassembled and taken out laminate can be atmospheric pressure. In addition, until now, there was friction between the stainless steel plate and the copper foil or polymer release film during cooling, but by eliminating this friction, the factors that hinder thermal contraction due to cooling of the resin will be reduced. Copper foil,
Only the minimum necessary materials are required to construct the laminate together with the base material, and it is thought that thermal contraction during cooling is more sufficient than in the past. If the disassembly temperature is lower than the glass transition temperature, most of the curing shrinkage and heat shrinkage have already been completed.
Even if subsequent contractions are allowed to occur freely, they have little effect. Examples The substrate for the laminate used in the present invention is paper, woven fabrics such as natural fibers, organic synthetic fibers, inorganic fibers, nonwoven fabrics, and mat, and is not particularly limited. Further, the resin used is a thermosetting resin such as an epoxy resin, a phenol resin, a polyester resin, a melamine resin, a polyimide resin, etc., but is not limited thereto. Furthermore, depending on the application, the copper foil may or may not be integrated into the surface, but the invention is not limited thereto either. Examples 1 to 3 Epoxy resin with an epoxy equivalent weight of 520 (trade name EP-
1001, manufactured by Yuka Ciel) 100 parts, dicyandiamide 4 parts, 2-ethyl-4-methylimidazole 0.3
A varnish with a solid content of 55 wt% was prepared.
The varnish was impregnated into a glass nonwoven fabric (weight 75 g/m ² ) and a glass woven fabric and dried, and the amount of resin was
A glass nonwoven fabric prepreg with a resin content of 77wt% and a glass woven fabric prepreg with a resin content of 40wt% were produced. After using six sheets of prepreg for the core layer and placing one sheet of prepreg on each surface layer, 18μ thick copper foil was placed on both surfaces, sandwiched between stainless steel plates, and heated at a pressure of 35Kg/cm ² and a temperature of Heat and pressure were applied at 170°C for 90 minutes. During cooling, the temperature of the laminate was 160°C (Example 1), 140°C (Example 2),
At 120° C. (Example 3), each laminate was dismantled and the laminate was taken out to obtain a laminate with a thickness of 1.6 m/m. Table 1 shows the measurement test results of the dimensional shrinkage rate of each laminate. The dimensional shrinkage rate is determined by drilling two 1φ holes in a 320 x 50 m/m test piece with a distance of 300 m/m between the holes, etching the test piece, treating it with E-0.5/170, and then The dimensional shrinkage rate was measured. Comparative Examples 1 to 2 Heat and pressure molding was performed in the same manner as in Examples, and when the temperature of the laminate was 100°C (Comparative Example 1) and 70°C (Comparative Example 2) during cooling, disassembly was performed and laminated. Got the board. Table 1 shows the dimensional shrinkage rate of each laminate.

[Table] Effects of the Invention As is clear from Table 1, according to the present invention, the resin undergoes sufficient thermal contraction during molding and cooling, so the dimensional shrinkage in the subsequent processing process of the laminate is kept smaller than before. Its industrial value is extremely large.

Claims (1)

[Claims] 1. In the production of laminates, the required number of prepregs are impregnated into a base material with thermosetting resin, dried and B-staged, sandwiched between stainless steel plates, heated and pressed to harden, and then cooled. A method for manufacturing laminates, which is characterized by dismantling at a temperature higher than the glass transition temperature (Tg) of the cured resin.