Activating catalytic solution for electroless plating and method of

Abstract

There is provided a method of forming a conductive film having a predetermined pattern in hybrid ICs, high frequency dielectric filters and the like which makes it possible to safely and efficiently perform a series of the steps of preparing an activating catalytic solution for forming a photoreactive film on a base, forming the photoreactive film through the application of the activating catalytic solution, producing an activating catalyst by exposing particular regions of the photoreactive film, developing by flushing away the photoreactive film in unexposed regions, and immersing the base in an electroless plating bath without using an organic solvent and which allows the formation of a plating film having high electrical conductivity and high strength of adherence. A hydrophilic activating catalytic solution is used which is obtained by dissolving copper oxalate, a palladium salt such as palladium chloride into an alkaline solution such as ammonia. Since the activating catalytic solution itself does not include any organic solvent, the photoreactive film can be flushed away in unexposed regions using water at the developing step, which allows immediate immersion into an electroless plating bath.