| 摘要 |
PROBLEM TO BE SOLVED: To form an insulating substrate layer easy to bore by laser by a method wherein a heat curable resin particle which is solid and cured at room temperature is dispersed among fibers having an organic fiber formed in a nonwoven state with a curable binder resin as an essential ingredient. SOLUTION: A sheet is made from a slurry containing a fiber having an organic fiber as an essential ingredient and a heat curable resin particle, a curable binder resin is applied to the obtained sheet, and then the curable binder rein is cured to a B stage or a C stage by heating to be dried. As the organic fiber to be used, a polyvinyl chloride based fiber such as a polyamide fiber, a polyvinyl chloride fiber, a vinylchloride-ethylene copolymer fiber, etc., polyvinylidene chloride fiber, etc., are given. As for the heat curable resin particle to be used which is solid and uncured at room temperature, particles of an epoxy-based resin, a phenol-based resin, a cyanate-based resin, a polyimide- based resin, or the like are given. |
