| 摘要 |
PURPOSE:To obtain a composite sheet usable as flexible printed circuit boards comprising a metal foil and a plastic layers, by casting and applying a heat-resistant high polymer solution to a metal foil, followed by aging at a specific temperature for a long time. CONSTITUTION:A solution of a heat-resistant high polymer, e.g. polyamide-imide, etc. is cast on a metal foil, e.g. copper foil, etc., and set to touch, preferably at 150 deg.C, then dried and solidified at 260-300 deg.C. The composite sheet thus obtained is aged at a temperature in the range of the drying one to ordinary temperature for a long time. Preferably, the aging temperature and time are controlled within the area surrounded by the lines connecting the four points (180, 5), (180, 30), (100, 8) and (100, 120). Aging in the atomosphere of an inert gas, e.g. nitrogen, etc. is preferred without degrading bond strength. |
