JPH035987B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a method for finishing a pressureless molded single-sided metal foil-clad laminate. A laminate made of paper, glass cloth, glass paper, etc. as a base material, laminated with multiple resin-impregnated base materials impregnated with a resin liquid, and cured, and a metal foil on one or both sides of the laminate. Metal foil laminates are used as insulating boards and printed wiring boards. Conventionally, these laminates were manufactured using a batch method in which prepregs obtained by impregnating the base material with resin varnish and drying were stacked and molded by pressurizing and heating. A continuous method for impregnating, laminating, curing, etc. with resin while continuously transporting materials has been developed and is attracting attention. For example, see Japanese Patent Application Laid-open Nos. 55-4838 and 56-98136 by the present applicant. For example, if you use an unsaturated polyester resin, epoxy acrylate resin, or epoxy resin that is liquid at room temperature and does not produce gas or liquid byproducts during curing, you can convert the laminate of impregnated base material covered with metal foil to polyester film. A single-sided metal foil-clad laminate can be produced by supporting on a removable cover sheet such as the above and curing and molding without applying molding pressure. Laminated plates formed under no pressure in this manner, particularly single-sided metal foil-clad laminates, tend to warp when heated or cooled because the materials that constitute them have different coefficients of thermal expansion. This warpage can be corrected by passing the laminate through a warpage straightening device, which usually consists of three rolls, to deflect the laminate in the opposite direction to the warp. Therefore, even if the warp is corrected, it tends to change over time. The present invention therefore relates to a finishing method for correcting warpage in such a laminate so that it does not return to its original shape.
In this method, a plurality of sheet-like base materials are impregnated with resin while being conveyed continuously, laminated with impregnated base materials, and laminated with metal foil, and then continuously cured and molded with virtually no pressure. The obtained single-sided metal foil-clad laminate is cut into a predetermined size, and after post-treatment if necessary, the cut laminate is aged and then straightened for warping. The process up to the step of cutting the non-pressure formed laminate can be carried out in exactly the same manner as the method described in the above-mentioned JP-A-5-4838 and JP-A-56-98136. In order to avoid lengthening the production line, if the material is cut after most of the curing has been completed but not completely, it is subjected to a post-curing process to complete the curing. Further, if necessary, the fully cured laminate is exposed to a humid, high temperature atmosphere to stabilize the characteristic values. The post-processing after cutting is described in the applicant's JP-A-Sho.
See 55-126419, 57-58396, etc. Chemically speaking, the laminate after such a process has been almost completely cured. Therefore, it would be efficient to wait for the product to cool down and then straighten the warp immediately before shipping it as a product, but the product will gradually return to its original state due to residual internal stress. According to the present invention, the cut laminate is aged and the warpage is corrected after a stable state is achieved. For this purpose, the devices and methods described in Japanese Patent Laid-Open Nos. 55-126419 and 57-156202 can be used. For aging, the laminates may be stacked at room temperature and left for one or more days, preferably three days or more. According to the present invention, the warpage does not come back unlike when the warpage of a laminate is corrected immediately after manufacturing, and stable warpage correction can be performed. Example 1 Maleic anhydride, isophthalic acid, and diethylene glycol were charged in a molar ratio of 1:1:2, respectively, and reacted by a conventional method, and diluted so that the styrene ratio was 35% by weight to obtain an unsaturated polyester resin. . 1 part by weight of a curing agent (Perhexa 3M, manufactured by NOF) is blended with 100 parts by weight of this resin.
This was used as an impregnating resin liquid. Five sheets of kraft paper are coated with melamine resin (Nicaresin S).
-305, manufactured by Nippon Carbide), the above was degassed under reduced pressure, each layer was individually impregnated with resin liquid, and after lamination, the top surface was coated with an epoxy resin adhesive. Foil, bottom side
Laminated with PET film, continuously heated and cured at 120℃ at a line speed with a residence time of 15 minutes, peeled off the PET film and cut to produce a single-sided copper-clad laminate with dimensions of 1020mm square and 1.6mm thick. I got it.
After further post-curing this material at 150℃ for 10 minutes,
200 sheets were loaded on a pallet and left in an aging room at a room temperature of 20°C to 25°C for 4 days. Each sheet was passed through three rolls in the vertical and horizontal directions, and the amount of warpage was corrected so that the amount of warpage of the regular-sized board was 0 to 10 mm according to the JIS method, and then the change in the amount of warp over time was measured. Table 1 shows the average value of 10 sheets of standard size. Example 2 In Example 1, the product was left in the ripening chamber at a room temperature of 20° C. to 25° C. for 36 hours, and the change over time in the amount of warp after warp correction was similarly measured. The results are shown in Table 1. Comparative Example In Example 1, the product was not aged at room temperature of 20° C. to 25° C., but the warp was straightened immediately, and the change over time in the amount of warp was measured. The results are shown in Table 1.

[Table] Unit: mm

Claims (1)

[Claims] 1. Obtained by impregnating a plurality of sheet-like base materials with resin while continuously conveying them, laminating the impregnated base materials, laminating metal foil, and then continuously curing and molding them under virtually no pressure. Single-sided metal, characterized in that a single-sided metal foil clad laminate is cut to a predetermined size, and if necessary, after post-treatment, the cut laminate is left at room temperature for one day or more to straighten the warpage after aging. How to finish foil laminates.