Abstract: A process is disclosed for forming a printed circuit board having improved adhesion of an electrically conductive layer to an underlying dielectric surface. A thin adhesive layer, or film, of conductive material (normally copper) is sputtered onto a dielectric substrate and through holes formed therein, after which the substrate, with the then amorphous sputtered layer thereon, is further processed in a manner so as not to damage adhesion of the sputtered layer to the substrate. The initial step of this further processing can be accomplished chemically or mechanically, and preferably is accomplished by electroplating a buffer, or transition, layer of conductive material onto the sputtered layer with the buffer layer being deposited by placing the substrate, having the sputtered layer thereon, in a first electroplating bath to produce an electroplated layer having no deposit stress or a slightly compressive deposit stress.

Abstract: An improved method is disclosed for forming a printed circuit board. The desired printed circuit is established on the surface of a plastic core sheet by placing recesses therein conforming to the desired circuit, and a conductive coating is then applied so that the coating is retained at the recesses. Circuit patterns are preferably pressed into one or both sides of the plastic core sheet, and holes can be placed through the sheet to allow circuit connections between the patterns on the opposite sides of the sheet and to receive electrical leads of circuit components. A thin conductive coating is applied by vacuum deposition, and can be thickness enhanced by electroplating.