A printed circuit which may be highly flexible in configuration and design includes at least one uniformly thick, planar circuit layer including a conductive circuit pattern and an insulating circuit pattern of a cured, flowable insulating material. The printed circuit may include multiple circuit layers...http://www.google.com.tw/patents/US4306925?utm_source=gb-gplus-share專利 US4306925 - Method of manufacturing high density printed circuit
