Method for manufacturing double-sided flexible printed board

摘要

A double-sided flexible printed circuit board is manufactured by the following steps of: (a) forming a polyimide precursor layer on a first metal layer; (b) forming a second metal layer on the polyimide precursor layer; (c) patterning the second metal layer to form a second circuit layer or (c') patterning the first metal layer to form a first circuit layer; and (d) imidating the polyimide precursor layer to form a polyimide insulating layer. The polyimide precursor layer is obtained by dissolving a polyamic acid or other polyimide precursor in N-methyl-2-pyrrolidone or the like and applying the resultant varnish to the first metal layer. The polyimide layer is then dried. The imidation ratio of the dried polyimide precursor layer is prevented from exceeding 50%.