JPH01215514A - Manufacture of laminated sheet for electricity - Google Patents

Abstract

PURPOSE:To manufacture a laminated sheet for electricity, which is free from a distortion and dispersion in the coefficient of thermal expansion, by a method wherein after low pressure pressing of a plurality of sheets of prepreg is performed under heating, the same is heated at the glass transition temperature of resin or higher. CONSTITUTION:A plurality of sheets of prepreg are placed between metallic plates and pressed at the lowest possible pressure. The pressure, for example, is 25kg/cm<2> in case of epoxy resin. Then the laminated sheet is heated at the glass transition temperature of resin or higher (170 deg.C or higher), a distortion within the laminated sheet is mitigated and dispersion in the coefficient of thermal expansion is made little. The laminated sheet for electricity whose reliability is improved drastically is obtained.

Description

[Detailed description of the invention] [Industrial application field]

The present invention relates to an electrical laminate with small variations in coefficient of thermal expansion.

[Prior art]

Previously, prepreg was produced by impregnating a base material such as gamma lath cloth or paper with thermosetting resin varnish and drying it, and then heating it by placing multiple sheets of prepreg between heating plates. Electrical laminates are manufactured by pressure pressing. When pressing a laminate, it is important to set the temperature and pressure to suit the prepreg. When pressing a multilayer board, the pressure is about 40 to 50 kg/am, but for a paper phenol laminate, the pressure is 70 kg/cm2 or more.The heating temperature is 165 to 175°C, and it is heat resistant with a high glass transition temperature. In the case of resin, even higher temperatures are used.

[Problem to be solved by the invention]

In conventional manufacturing methods, distortion occurs in the wall of the resulting laminate due to resin flow during molding, and this distortion varies depending on the size of the resin flow, and is larger at the edges of the board than in the middle. . This strain is alleviated when the laminate is heated and softened, resulting in shrinkage of the laminate and variations in the coefficient of thermal expansion of the plate. Furthermore, the ratio of the base material to the resin varies due to resin flow, which causes variation in the coefficient of thermal expansion of the plate. The present invention has been made in view of the above circumstances, and its purpose is to provide a method for manufacturing a highly reliable electrical laminate with small deviations in board thickness and small variations in coefficient of thermal expansion. There is a particular thing.

[Means to solve the problem]

The method for producing an electrical laminate of the present invention involves impregnating a base material with a resin varnish and drying it to obtain a prepreg, laminating a plurality of prepregs using a low-pressure press under heat, and then heating the resin to a temperature higher than its lath transition temperature. This configuration achieves the above object. [Effect 1] Multiple sheets of prepreg are laminated using a low-pressure press under heat, so there is less resin flow and the sheet thickness deviation is small. The distortion of the meat is alleviated, the variation in the coefficient of thermal expansion is reduced, and the reliability is improved. The base material used in the present invention may be paper, organic fiber cloth, inorganic fiber cloth, etc., but low thermal expansion base materials such as aromatic polyamide fiber cloth and Q-glass cloth are preferable. 7 enol resin (Tg: 120-130℃) on this base material
, epoxy resin (Tg: 130-150°C), BT resin (Tg: 240-330°C), polyimide resin (Tg:
260-300℃), polyester resin (Tg: 120
~130℃), polybutanoene resin (Tg: 260~3
00°C), melamine resin (Tg: 110-130°C),
A resin varnish such as urea resin (Tg: 80 to 110°C) is impregnated and dried. Drying temperature is 120-170°C. It is preferable that the drying time is longer than usual, and in order to reduce resin flow during molding, it is preferable that the melt viscosity and resin content of the resin are small. Next, place multiple prepregs on the metal plate, or as desired. ! 4 Foils or copper clad plates for the outer layer, multiple sheets of prepreg, copper clad plates for the inner layer, etc. are laid up in order with the opening of the mirror plate, placed on a hot platen, and pressed under heat and low pressure to produce electrical laminates. do. In this case, press at the lowest possible pressure. For example, for epoxy resin, it is 25 kg/am2 or less. The heating temperature is the same as before. Further, by performing heating and pressure molding in a vacuum, the formation of voids is suppressed and distortion is further reduced. A printed wiring board is manufactured from the electrical laminate thus manufactured by a conventional method. Next, the present invention will be explained in detail. In the following, % indicates weight %. (Example) After plasma treating the surface of an aromatic polyamide fiber cloth ("Kevlar Cloth" (trade name), manufactured by DuPont) with a thickness of 0.1a+-, a curing agent-containing epoxy resin varnish (Tg:
145° C.) and dried to produce prepreg A. Drying conditions are resin content 40%, melt viscosity 300~
The stroke was 400 poise and 140 to 155 seconds. Separately, prepreg B and prepreg C were prepared by impregnating aromatic polyamide fiber cloth ("Kevlar cloth") with a hardening agent-containing resin varnish with a thickness of 0.2 ram and 0.1 am, and drying it. The drying conditions were the same as those for prepreg A. Next, the laminate in which two sheets of prepreg A were stacked and a release film was placed on both sides was sandwiched between metal plates, and the molding pressure was increased to 25°C.
kg/am2, after vacuum forming at a molding temperature of 170°C for 100 minutes, the release film on both sides was removed to give a thickness of 0.2 mm.
A laminate A was obtained. Laminate C was obtained from prepreg C in the same manner. After this, a laminate in which four sheets of prepreg B were stacked and laminate plates A and laminate C were arranged on both sides was sandwiched between metal plates and vacuum formed for 100 minutes at a molding pressure of 25 kg/cm2 and a molding temperature of 170°C. A laminate with a thickness of 1° to 2 mm was manufactured. The laminate was then heated in an electric oven at 170° C. for 15 minutes and air cooled. The thickness and coefficient of thermal expansion of this laminate were measured. The results are shown in Table 1. (Comparative Example 1) Drying conditions were resin content 50%, 400 to 500 p Oj
Prepreg A, prepreg B, and prepreg C were produced in the same manner as in the example except that the stroke was 120 to 140 seconds. Next, the laminate in which two sheets of prepreg A were stacked and a release film was placed on both sides was sandwiched between metal plates, and the molding pressure was increased to 50°C.
kg/cI112, after vacuum forming for 100 minutes at a molding temperature of 170°C, the release film on both sides was removed and the thickness was 0.
．． A laminate A of 2III1 was obtained. Laminate C was obtained from prepreg C in the same manner. After this, a laminate in which four sheets of prepreg B were stacked and laminate plates A and laminate C were arranged on both sides was sandwiched between metal plates, and the molding pressure was 50 kg/0 m2 and the molding temperature was 170.
A laminate with a thickness of 1° and 2 mm was produced by vacuum forming at ℃ for 100 minutes. The laminate was then heated in an electric oven at 170°C for 15 minutes and air cooled. The thickness and coefficient of thermal expansion of this laminate were measured. The results are shown in Table 1. (Comparative Example 2) A laminate was produced in the same manner as in the example, heated in an electric oven at 100°C for 15 minutes, and cooled in air. The thickness and coefficient of thermal expansion of this MI laminate were measured. The results are shown in Table 1. (Comparative Example 3) A stacked board was produced in the same manner as in the example, and was allowed to cool without being heated in an electric oven. The thickness and coefficient of thermal expansion of this laminate were measured. The results are shown in Table 1. First surface plate thickness (m+) Coefficient of thermal expansion (PPM/'C) ,
Best example 1,25 1.19 0,06 6,3 4,
5 1.8 Comparative Example 1 1,24 1,12 0,12
6,2 3,2 3.0 Comparative example 2 1.25 1,18
0.06 6,2 3.8 2.431.25 1.
19 0.06 6,2 3,7 2.5 From the results in Table 1, it is clear that when the variation in plate thickness is large as in Comparative Example 1, the variation in coefficient of thermal expansion also becomes large. Example, Comparative Example 2, and Comparative Example 3), it can be seen that the variation in the coefficient of thermal expansion becomes smaller when heating is performed above Tg after molding as in the example.

【Effect of the invention】 【Effect of the invention】

In the present invention, since a plurality of sheets of prepreg are laminated and molded using a low-pressure press under heat, there is little resin flow and thickness deviation is small.
Since it is heated above the lath transition temperature, the distortion of the plate thickness is relaxed and the variation in the coefficient of thermal expansion is small, making it possible to manufacture electrical laminates with significantly improved reliability. Patent Attorney Ishi 1) Ai Shichi

Claims (2)

[Claims] (1) Electrical laminate characterized by impregnating a base material with a resin varnish and drying it to obtain a prepreg, laminating a plurality of sheets of the prepreg using a low-pressure press under heat, and then heating at a temperature equal to or higher than the glass transition temperature of the resin. Method of manufacturing the board. (2) The method for manufacturing an electrical laminate according to claim 1, wherein the base material is an aromatic polyamide fiber cloth.