PROCESS FOR PRODUCING THIN COPPER FOIL-CLAD CIRCUIT BOARD SUBSTRATE

摘要

A process for producing a thin copper foil-clad circuit board substrate which comprises subjecting a copper foil-clad circuit board substrate (a) comprising an electrically insulating support overlaid on one or both sides with a copper foil having an average thickness of 12 mu m or more to etching with a copper-etching solution thereby to etch the whole surface of the copper foil at a predetermined etching rate selected from the range of from 0.01 to 0.4 mu m/sec, thereby to reduce the thickness of the copper foil on at least one side of the insulating support to 10 to 80 % of its original thickness with the thickness variation of the remaining etched copper foil being within +/-1.0 mu m on the basis of a desired thickness, wherein said copper foil-clad circuit board substrate (a) is one in which the surface of the copper foil is substantially free of adherent dust particles having an average particle diameter of 3 mu m or more.