Abstract: A process for producing printed circuits including a dry substrate activation process and copper deposition without electroless plating is disclosed. The process requires fewer wet chemical baths, is less environmentally hazardous, and more efficient than conventional processes. Initially, sacrificial copper layers are laminated to the surface of a prepreg substrate and through holes are drilled therein. The sacrificial layer is then removed by etching and copper is sputter deposited upon the substrate surface and the walls of the through holes. Photoresist is then applied, exposed and developed to create the desired pattern of circuit lines. Next, copper is deposited in the photoresist channels and on the through hole walls by electroplating. After the photoresist is stripped, the exposed sputtered copper is removed by differential etching.

Abstract: After cleaning and removal of oxidic layers, the defective copper conductors are completely etched off the surface of the external planes of a multilayer circuit board, and the copper on the walls of the plated through holes is etched at an etching rate continuously decreasing toward the center of the hole walls. Subsequently, an activating layer of copper is applied on the surface of the substrate and on the adjacent parts of the surface of the hole walls. Copper conductors defined by a photoresist mask in a known manner, are deposited on the surface of the activating layer following the additive technique, the copper is deposited on the entire surface of the hole walls. As the maximum etching depth of the copper on the hole wall is approximately 0.2 mm maximum, and as the activating layer is applied up to a depth of approximately 1.2 mm a perfect copper overlap on the walls is ensured.

Abstract: A method of improving the adherence of conductive metallic lines to a polyimide resin layer by incompletely curing the polyimide resin prior to deposition of the metal layer, and subsequently completely curing the polyimide resin layer after the metal layer is deposited.

Abstract: A composition for etching polyimide based polymers comprised of a tetraalkyl ammonium hydroxide and an organic acid selected from the group of acetic acid, tartaric acid and oxalic acid.The etchant may be used to texture polyimide films or form perforations through polyimide substrates or layers, particularly in the fabrication of printed circuits and semiconductor devices where via holes are required for interconnection of circuitry.