JPS602333A - Manufacture of laminate plate - Google Patents

Abstract

PURPOSE:To manufacture laminate plates free of warping and torsion by a method in which processes of depressurization and pressurization are repeated 1-3 times in molding a laminate plate by hot-pressing laminated pre-pregs impregnated with a resin. CONSTITUTION:A given number of pre-pregs formed by impregnating a thermosetting resin into a base material and then drying it are laminated and hot-pressed to form a laminate plate. In such a process, processes of depressurization and pressurization are repeated 1-3 times. Accumulated strain in the laminate plate can thus be dispersed and eased to relieve warping and torsion. The depressurizing time is equal to the time of pressing operation, or preferably 0.5-5min, because no complete no-load is obtained when depressurized if the depressurizing time is too short, and also because interlayer delamination occurs in the laminate plate if the depressurizing time is too long.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for manufacturing a laminate with less warpage and twisting.

In recent years, the wiring density of printed wiring boards has increased, and
As the automation of machining processes progresses, strict requirements are being made to suppress warpage and twisting.

However, the laminate board that is the substrate for printed wiring boards,
Warpage and twisting occur due to the difference in thermal shrinkage rate between the base material and the resin. In order to suppress this warpage and twisting, the rate of increase in heating temperature and molding pressure during laminated board molding may be adjusted.
Various improvements have been made, such as changing the melt viscosity of the resin and considering the structure of the base material, but they are still not sufficient.

The present invention focuses on molding pressure, which is relatively easy to control, and aims to produce a laminate with less warpage and twisting.

In order to achieve the above object, the present invention has the following features: In the step of forming a laminate by stacking a predetermined number of prepregs obtained by impregnating and drying a thermosetting resin into a base material and heating and pressing them, the following steps are taken: The process of returning to the original pressure (called depressurization) is 1.
It is characterized by repeating ~3 times.

If heating and pressing are continued consistently, the resin will harden with residual distortion, resulting in the formation of a laminate that is susceptible to warping and twisting.

On the other hand, in the present invention, since the pressure is once removed during heating and pressurization, the strain that had been accumulated up to that point is dispersed and relaxed, and a laminate with less warpage and twisting can be produced. If the pressure is released and then the pressure is returned to the original level, the interlayer adhesion of the laminate may deteriorate or new distortion may occur, so this should be avoided.

Incidentally, the time for depressurization is the time for the press operation, and if it is too short, it may not be possible to completely release the load even after depressurizing, and if it is too long, there is a risk that delamination of the laminate may occur. The depressurization time is preferably α6 to 5 minutes.

The present invention will be explained in detail below.

Example 1 Glass nonwoven fabric base material 5 prepregs obtained by impregnating and drying epoxy resin were stacked together, sandwiched between C mirror plates, and the 6 sets were inserted into a press hot plate and heated and pressurized. . The heating and pressurization was carried out in a pattern as shown in Drawing 1.

In other words, as shown by curve a, the temperature of the press heating plate is set to 17
Heating is carried out by holding at 0° C. for 70 minutes. Curve C shows the temperature change of the prepreg located at the center between the press hot platens, and the pressure indicated by curve @b was maintained at 20:9/C1l until the temperature reached 130°C, and then the pressure was increased to soy/cd.

After 50 minutes had passed after heating, the pressure was depressurized for 1 minute to a no-pressure state, and the pressure was increased to the original pressure of 80#/cIIt.
After a few minutes, similar depressurization and pressure increase were performed again to form six laminates with a thickness of 1 m.

Example 2 A laminate was molded in the same manner as in Example 1 except that the steps of depressurization and pressure increase were performed once.

Comparative Example A laminate was molded in the same manner as in Example 1, except that the steps of depressurization and pressure increase were repeated four times.

Conventional Example A laminate was molded under the same heating and pressing conditions as in Example 1 without depressurizing even once.

Each of the laminates obtained as described above was cut into sample pieces of 400 x 200 circles, and warpage and torsion were measured in accordance with JIS-C-6481i at normal conditions and after heating at 150°C for 30 minutes. The results are shown in Table 1. Each measured value of warp and twist in the table indicates the maximum value under normal conditions to the maximum value after heating.

Table 1 As is clear from Table 1, according to the present invention, it was possible to obtain a laminate with less warpage and twisting, and the variation in warpage and twisting that occurred was also small. Also,
Since the present invention is based on pressure control, it is relatively easy to operate, and its industrial value is extremely great.

[Brief explanation of the drawing]

The drawing is a curve diagram showing changes over time in temperature and pressure in laminated molding in one embodiment of the present invention. a is the press platen temperature, b is the pressure, and C is the prepreg temperature.

Claims (1)

[Claims] L In the step of forming a laminate by heating and pressing a predetermined number of sheets of prepreg obtained by impregnating and drying a base material with a thermosetting resin, the pressure is once released and the original pressure base is restored. A method for producing a laminate, characterized by repeating the reconstitution step 1 to 3 times. 2. The method for manufacturing a laminate according to claim 1, wherein the time period during which the pressure is released is 0.5 to 5 minutes.