Process for producing a printed circuit board

Disclosed is an improvement of a process for producing a printed circuit board by the so-called photo-forming method, comprising (A) a step of providing an adhesive layer on one side or both sides of an insulating substrates, (B) a step of roughening, and imparting a hydrophilic property to, the surface of said adhesive layer by a physical or chemical method, (D) a step of forming on the substrate a light sensitive material layer containing a metal in a reducible oxidized state capable of forming catalytic nuclei for non-electrolytic plating, and a light sensitive reducing agent, (E) a step of reductively precipitating metal particles constituting catalytic nuclei by selectively exposing said light sensitive material layer, and (F) a step of forming a conductor circuit layer by non-electrolytic plating after removing non-exposed portions of said light sensitive material layer; wherein the improvement comprises providing between the step (B) and the step (D), a step (C) of depositing fine particles of a light sensitive metal oxide semiconductor at least on the inner wall surface of a through hole.