JPH06114865A - Production of laminated sheet - Google Patents

Abstract

PURPOSE:To obtain a laminated sheet reduced in strain without increasing the number of processes by cooling all of laminated sheets at a cooling speed of a specific value or less per min within the glass transition temp. range of the laminated sheets at the time of cooling after heating. CONSTITUTION:At the point of time when an outer laminated sheet is cooled to temp. higher than the glass transition temp. of the laminated sheet by 10 deg.C or slightly higher, the temp. or flow rate of the heating medium circulating through a hot plate is adjusted in order to decrease a cooling speed to control the temp. of the hot plate. By this operation, all of laminated sheets during molding are cooled at a cooling speed of 7 deg.C or lower, pref., 2 deg.C or lower per min within the temp. range of glass transition temp. + or -10 deg.C. By repeating this operation any number of times, all of the laminated sheets during molding are cooled at a cooling speed of 7 deg.C or lower, pref., 2 deg.C or lower per min within the temp. range of glass transition temp. + or -10 deg.C. By this constitution, the strain and warpage level of the laminated sheet can be reduced.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a laminated plate which has little distortion and is excellent in dimensions and warpage.

[0002]

2. Description of the Related Art Conventionally, as a method for producing a laminated plate with less distortion, there has been a method of molding at low pressure or a method of taking strain by reheating without pressure after molding. However, the latter has a defect that the number of processes increases in the latter case.

[0003]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a laminated plate having less strain without increasing the number of steps by cooling at a cooling rate of 7 ° C. or less per minute near the glass transition temperature.

[0004]

DISCLOSURE OF THE INVENTION The present invention relates to a laminated plate in which a base material is impregnated with a resin varnish, and one or a plurality of the resin varnishes are superposed to form one set, and three or more sets are simultaneously heated and pressed between hot plates. In the manufacturing method, when cooling after heating, all the laminated plates are cooled at a cooling rate of 7 ° C. or less per minute in the temperature range of the glass transition temperature ± 10 ° C. of the laminated plates. Is. As mentioned above,
The conventional methods have drawbacks such as defective molding and a large number of steps. Further, as a method of obtaining a laminated plate with less distortion, it is sufficient to cool the heating plate slowly after the end of heating, but there is a drawback that the cooling time becomes long.

The present invention solves such drawbacks by cooling the laminate at a glass transition temperature of ± 10 ° C. at a cooling rate of 7 ° C. or less per minute, thereby reducing the cooling time. Without increasing the length, it is possible to reduce the strain of the obtained laminate and reduce the level of warpage. In carrying out the method of the present invention, the same resin formulation, the same substrate,
The glass transition temperature (Tg) of the laminated plate formed by applying under the same conditions is measured in advance. All of the prepregs inserted between the hot plates, that is, external push (insertion position closest to the hot plate)
Measure the temperature of the hot plate to the middle press (insertion position far from the hot plate) and the hot plate with a thermocouple.

[0006] Molding is performed with such a constitution, and the cooling rate is reduced when the externally pressed laminate is cooled to a temperature of 10 ° C or slightly higher than the glass transition temperature in the cooling process after heating and pressurizing. To this end, the temperature and flow rate of the heat medium circulating in the heating platen are adjusted to control the heating platen temperature. By this operation, all the laminated plates being molded are cooled at a cooling rate of 7 ° C. or less per minute, preferably 2 ° C. or less per minute in a temperature range of glass transition temperature ± 10 ° C. By repeating this test operation several times, all the laminated plates under molding have a glass transition temperature of ± 10 ° C. in a temperature range of 7 ° C. or less per minute,
Preferably, conditions are determined so that the cooling rate is 2 ° C. or less per minute. Hereinafter, actual laminated board molding is performed based on these conditions.

[0007]

EXAMPLES Examples of the present invention and comparative examples (conventional examples) are shown below. The composition of the epoxy resin varnish is as follows.

[Table 1] The above materials were mixed to form a uniform varnish.

Comparative Example The above varnish was applied to a glass woven cloth having a thickness of 0.18 mm (mass 205 g / m ² ) with a resin content of 42 to
The glass woven fabric prepreg was impregnated and dried to 45% by weight. Eight sheets of this prepreg were piled up, and a copper foil of 18 μm was piled up and down as one set, and 10 sets were inserted between a pair of hot plates, and pressure heating was carried out. After the heating at the maximum temperature of 180 ° C. was completed, it was cooled at a cooling rate of 15 ° C./min to obtain a copper-clad laminate having a thickness of 1.6 mm. The glass transition temperature of this laminate was measured by thermomechanical analysis (TMA),
A value of 5 ° C. was obtained.

Example 1 Similar to the comparative example, a prepreg is inserted between hot plates and pressure heat molding is performed, cooling is started after heating is completed, and the cooling rate is reduced when the external push reaches 150 ° C. By controlling the hot platen temperature in this way, it was confirmed that the cooling rate of the external push was 2 ° C./min, and that of the intermediate push was 2 ° C./min. Pushing outward,
When the temperature reached 120 ° C. or less in both cases of the medium pressing, the cooling rate of 15 ° C./min was entered to obtain a copper-clad laminate having a thickness of 1.6 mm.

Example 2 In the same manner as in the comparative example, the prepreg was inserted between the heating plates to perform pressure heating molding, cooling was started after the heating was completed, and the external pressing reached 160 ° C. Example 1
Control the hot platen temperature in the same manner as above to confirm that the cooling rate for external push and middle push is 2 ° C / min.
At a cooling rate of 1.6 mm to obtain a copper clad laminate having a thickness of 1.6 mm.

With respect to the copper clad laminates obtained from the above Examples and Comparative Examples, the dimensional change rate and warpage in the working process were measured. The results are shown in Table 2.

[Table 2]

(Measuring method) Dimensional change rate: Measured according to JIS C 6481 Warp: Measured according to JIS C 6481 As is apparent from Table 2, in the temperature range of glass transition temperature ± 10 ° C., every minute It can be seen that the copper-clad laminate obtained by cooling at a cooling rate of 7 ° C. or less has little distortion and is excellent in warpage and dimensions.

[0013]

According to the present invention, by cooling at a cooling rate of 7 ° C. or less per minute in a temperature range of glass transition temperature ± 10 ° C., distortion is less and warpage is less than that of a conventional laminated plate without increasing man-hours. Also, it is possible to provide a laminated plate having a reduced dimensional shrinkage rate.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification code Office reference number FI technical display location B32B 31/20 7639-4F // B29K 105: 06

Claims (1)

[Claims] 1. A base material is impregnated with a resin varnish, and one or a plurality of the resin varnishes are superposed to form one set, and three sets are provided between the heating plates.
In the method for producing a laminated sheet in which the set or more are heated and pressed at the same time, the glass transition temperature of the laminated sheet is ± 1 when cooled after heating.
A method for producing a laminated plate, which comprises cooling all the laminated plates at a cooling rate of 7 ° C. or less per minute in a temperature range of 0 ° C.