JPS6068941A - Manufacture of laminated board - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a manufacturing method for suppressing warping of paper-based laminates.

Metal foil-covered laminates for printed circuits are subjected to repeated humidification and heat treatment during the circuit board manufacturing process, which causes warping or twisting of the laminate board, which often causes problems during circuit board manufacturing work or parts assembly work. . In particular, as substrate work sizes increase, circuit densities increase, processing processes become more automated, and heating process cycles increase, requirements for preventing warping and twisting of substrates are becoming increasingly strict.

Paper-based single-sided metal foil-covered laminates have an asymmetrical structure, with one side made of metal foil and the i side made of a synthetic resin-impregnated base material. Complex warping and twisting occur due to the difference in expansion and contraction with the substrate. That is, humidification occurs and the metal foil side becomes convexly warped.

Conventional paper-based laminates coated with metal foil on one side have the disadvantage that they cannot meet the severe demands for preventing warping and twisting as described above.The present invention solves the above-mentioned disadvantages and can withstand the severe conditions of humidification and heat treatment. The purpose of the present invention is to provide a paper base laminate that exhibits particularly little twist during the circuit board manufacturing process described below.

The present invention is characterized in that when laminating and molding prepreg obtained by impregnating and drying a synthetic resin into a paper base material, the wide sides of the prepreg at the center in the thickness direction are brought into contact with each other during paper base paper manufacturing. .

When paper base material is made, the felt side and the wire side have different paper densities, fiber arrangement, and fine fiber content, and in particular, many fine fibers coexist on the felt side. The present invention focuses on this point. That is, the contact between the felt surfaces of the prepregs has a large dimensional change (expansion during molding is large).

In particular, the amount of change at the center in the thickness direction is remarkable.

On the other hand, when the wire surfaces contact each other, there is little dimensional change during molding (, the difference in expansion and contraction between the surface in the thickness direction and the center is small (, and internal strain is small, so twisting occurs after molding and heat treatment). It is possible to obtain a laminate with less.

The present invention will be explained in detail below.

Example synthetic resol? 51' and 750 g of tung oil were heated to 80-85°C in the presence of 09 g of para-toluenesulfonic acid and reacted for 3 hours. Next, 25 thiammonia water 24g, 8
5% paraformaldehyde 30019 and methanol 1
00I was added and reacted at 80-85°C for 4 hours. Next, after concentrating under reduced pressure, the mixture was diluted with a toluene-non-metal mixed solvent (mixing ratio 1:1) to obtain a tung oil modified phenolic resin varnish with a resin content of 50 parts.

Next, 1/mils high-density kraft paper was impregnated with the obtained varnish and dried at +20'C to obtain a prepreg with a resin content of 46%. In this combination of 8 plies of prepreg, the two prepregs at the center in the thickness direction have their wire surfaces in contact with each other, and the 2.3 ply prepregs from both surfaces have their felt surfaces in contact with each other, and each prepreg from both surfaces l. For the second ply of prepreg, avoid contact between the felt side and the wire side, stack a sheet of 35 μ thick copper foil coated with adhesive on one surface, and heat at 17 µm.
A single-sided copper-clad laminate with a thickness of 1.6 mm was obtained by heating and pressing at o0c, rE force + 00 K9/cI& for 60 minutes. The combined configuration of prepreg and copper foil is shown in Figure 1. 1
is prepreg, 2 is wire surface, 3 is felt surface, and 4 is copper foil.

Comparative Example 1 As a combination configuration of the 8 prepregs obtained in the example, the two prepregs at the center in the thickness direction are brought into contact with the felt surface, and the other prepregs are brought into contact with the felt surface and the wire surface, A single-sided copper-clad laminate having a thickness of 1.6M was obtained in the same manner as in the example. The combined configuration of prepreg and copper foil is shown in Figure 2.

Comparative Example 2 As a combination configuration of 8 prepregs obtained in the example, the felt surface and wire surface of all of them were in contact with each other,
A single-sided copper-clad laminate having a thickness of 16 cm was obtained in the same manner as in the example.

The combined configuration of prepreg and copper foil is shown in Fig. 3.

The dimensional changes of each laminate obtained in the above Examples and Comparative Examples are shown in FIG. 4, and the torsion is shown in FIG.

The dimensional changes in Fig. 4 are as follows: 250 x 250n markings are applied to the 2nd and 4th ply prepregs from the surface.
It shows the amount of change in the lateral direction after processing. iAl represents the example, fBl represents the amount of change in Comparative Example 1, and (C) represents the amount of change in Comparative Example 2, where the curve a represents the change in the second ply from the surface, and the curve a represents the change in the fourth ply. Also, the fifth
The torsion in ♂ in the figure shows the torsion 4 of each laminate after E-8-/+60 treatment. It can be seen that the material according to the present invention has less dimensional change and less twist.

As described above, the present invention provides paper-based laminates by arranging the prepregs in the central part in the thickness direction so that their wire surfaces are in contact with each other, thereby reducing dimensional changes inside the laminate during molding and reducing internal strain. It has an extremely large industrial value, as it can reduce distortion caused by humidification and heat treatment in the subsequent circuit board manufacturing process, and is fully compatible with larger circuit board work sizes and higher circuit densities. .

[Brief explanation of drawings]

FIG. 1 is a cross-sectional view showing the layer structure of prepreg in an example of the present invention, FIGS. 2 and 3 are cross-sectional views showing the layer structure of prepreg in a comparative example, and FIG. 4 is a cross-sectional view showing the layer structure of prepreg in an example and a comparative example. FIG. 5 is a curve diagram showing the dimensional change of the laminate, and FIG. 5 is a bar graph showing the same twist. 1 is prepreg, 2 is wire side, 3 is felt side, 4
Copper foil patent applicant

Claims (1)

[Claims] A laminate board characterized in that when a paper base material 1 and a prepreg obtained by impregnating and drying a synthetic resin are laminated and molded, the wire surfaces of the prepreg at the center in the thickness direction are kept in contact with each other during paper base paper manufacturing. manufacturing method.