High-density fine-line printed circuits prodn. - by forming circuit on a substrate, laminating a flowable insulating film and removing film and circuit pattern from substrate

摘要

Printed circuit is formed by (a) placing a layer of photosensitive material of thickness at least equal to the conductor thickness on a smooth polished substrate surface, (b) placing a mask pattern on the layer, (c) developing and removing material exposed by the pattern, (d) forming a smooth conductive circuit pattern, (e) removing all remaining photosensitive material, (f) laminating a uniformly thick preformed film of flowable insulator (pref. polyamide imide) to the surface and the conductor pattern, and (g) stripping the insulator sheet and conductive pattern from the substrate.