JPS6411466B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a laminated board used as an electrical insulating board, etc., and an object of the present invention is to suppress the occurrence of warping and twisting. Synthetic resin laminates are made by impregnating a continuous sheet-like fibrous base material such as paper, glass woven fabric, glass non-woven fabric, cloth, etc. with synthetic resin varnish such as phenolic resin or epoxy resin and drying the prepreg to a predetermined length. It is manufactured by cutting, stacking a predetermined number of sheets, and applying heat and pressure. Prepreg is cut to a predetermined length and stacked, and for convenience of work, it is customary to take out a predetermined number of stacked prepregs in the order in which they were stacked, stack them, and heat and press them when manufacturing a laminate. In this case, continuous long sheets of paper, woven fabrics, non-woven fabrics, cloth, etc. have uneven papermaking during manufacturing and uneven coating during coating. Since this unevenness tends to occur continuously, distortion is amplified in laminates manufactured by stacking a predetermined number of sheets using the method described above, and further warping occurs due to heating during punching, etc. Twisting tends to increase. In view of the above-mentioned points, the present invention aims to suppress the occurrence of warping and twisting of a laminate due to uneven paper manufacturing of continuous base materials and uneven coating of resin varnish. The method of the present invention involves impregnating a continuous long sheet-like base material with synthetic resin varnish, drying it, and cutting it into predetermined lengths to obtain prepregs. This is a method for manufacturing a laminate, which is characterized by stacking the sheets and forming them under heat and pressure. According to the present invention, even if the lot of prepregs is the same, by stacking the prepregs with the front and back sides alternately, it is possible to cancel out the unevenness of paper manufacturing of the base material and the unevenness of coating of the resin, thereby achieving uniformity. A laminate is obtained. In the conventional method, prepregs from the same lot are stacked as they are, so unevenness in the papermaking of the base material and unevenness in the coating of the resin overlap, resulting in distortion when the laminate is made. Next, examples of the present invention will be described. Example 1 A continuous long piece of 11 mils bleached kraft paper was impregnated with 45 to 48% of tung oil-modified phenolic resin and dried.
Three sheets of prepreg cut into mm x 1055 mm were stacked with the front and back alternated, with the base material direction unchanged, and copper foil was placed on the surface, and this was laminated and molded for 60 minutes at a temperature of 170℃ and a pressure of 80Kg/ ^cm2.0.6 A mm-thick copper-clad laminate was obtained. This is called Invention A. Example 2 Eight sheets of prepreg obtained in the same manner as in Example 1 were stacked with the front and back sides alternated, and laminated and molded under the same conditions as in Example 1 to obtain a 1.6 mm thick copper-clad laminate. This will be referred to as Invention B. Example 3 Twelve sheets of prepreg obtained in the same manner as in Example 1 were stacked with the front and back sides alternated, and laminated and molded under the same conditions as in Example 1 to obtain a 2.5 mm thick copper clad laminate. This will be referred to as Invention C. Comparative Examples 1 to 3 The same prepregs as in Example 1 were stacked in one direction (without alternating the front and back), but in the same manner as in Examples 1 to 3.
Copper-clad laminates with a thickness of 1.6 mm and 2.5 mm were obtained. These laminates are referred to as comparative products D, E, and F, respectively. Each laminate obtained in the above Examples and Comparative Examples was
A sample was cut to 320 mm, printed and etched on the copper foil, and then punched out to a size of 300 mm x 200 mm using a $60 press to give a residual copper content of approximately 50%, and the same sample was heated at 160°C for 60 minutes. Table 1 shows the results of measuring the amount of twist and warpage of the sample. The number of samples is
20 pieces each. The method for measuring torsion is to place the sample on a table with its smooth convex surface facing up, press each of the four corners, and find the maximum value of the uplift of the diagonal corners. In addition, the warpage measurement method involves placing the sample on a table with the convex surface facing up, and determining the inner radius from the table surface to the highest position of the convex portion of the sample.

[Table] As can be seen from the results in Table 1, according to the present invention, a good laminate with no particular twist and little variation in warpage was obtained. As explained above, sheet-like materials that are generally manufactured continuously (paper, glass cloth, glass nonwoven fabric, prepreg using cloth, etc.) tend to have a density distribution (unevenness) in the flow direction. This tendency is further amplified in the case of laminates obtained by stacking the sheets in the same order as they were cut. However, in the present invention, the substrates are aligned in the same direction and stacked with the front and back sides alternately stacked, so these density distributions (unevenness) are canceled out and become uniform, resulting in a good laminate without twisting or warping. can be provided.

Claims (1)

[Claims] 1 A continuous sheet-like base material is impregnated with a synthetic resin, dried, and cut into a predetermined length. A pre-preg is obtained by stacking a predetermined number of prepregs with the base material directions aligned and the front and back sides alternated, and then heated and pressurized. A method for manufacturing a laminate.