Abstract: Printed circuit boards with plated through-holes are prepared by an electroless plating process using a self-supported, adherent, photohardenable sheet. The self-supported photohardenable sheet preferably is composed of a photopolymerizable material and may be a thick, homogeneous sheet or it may be a sheet reinforced with a foraminous material therein. The self-supported sheet is imagewise exposed to actinic radiation to form an adherent circuit pattern thereon comprising the unexposed areas. Through-holes are introduced into the pad areas of the circuit pattern, powdered catalyst is applied to the adherent pattern and through-holes and the catalytic image is plated in an electroless plating bath. The self-supported sheet may be used without additional catalyzing steps to make single sided, two-sided or multilayered printed circuit boards with plated throughholes and interconnections.

Abstract: An improved process for preparing printed circuit boards whereby through-holes are introduced into an element comprising a substrate, a photosensitive resist layer, and a superposed, strippable support. The through-holes are catalyzed prior to removal of the strippable support. After exposure the imaged photoresist is developed, the catalyzed-through-holes are electrolessly plated and the printed circuit is prepared using the developed image. Single sided, two or more layered printed circuit boards with plated-through-holes and interconnections can be prepared by this process.