PURPOSE: To produce prepreg for printed circuit board having improved drying workability, impregnating properties to substrate and excellent heat resistance, by impregnating a substrate with varnish blended with a solid epoxy resin as a resin component and drying.
CONSTITUTION: (A) A solid epoxy resin (e.g. bisphenol A type) having preferably 500W2,000 average molecular weight is blended with (B) 0.01W1 equivalent based on 1 equivalent component A of tetrabromobisphenol A, (C) 0.5W1.5 equivalent based on the component A of a polyhydric phenol (e.g. bisphenol), (D) 0.01W5pts.wt. based on 100pts.wt. component A of curing promoter, preferably an imidazole compound containing an imino group masked with acrylonitrile, etc., and (E) a solvent (e.g. acetone) to give varnish, which is impregnated into a substrate such as glass cloth and dried in a drying furnace at 60W200°C to produce prepreg.
FUKUDA TOMIO
KOBAYASHI KAZUHITO
HOSHI IKUO
YUSA MASAMI
