Patent ID: 7434311

Claim:
A printed wiring board manufacturing method comprising the steps of: (a) providing a number of through holes in a substrate made of an insulating material coated with a copper foil; (b) forming a conductive film for making the inside of the through holes electrically conductive; (c) coating an outer surface of the substrate with a photosensitive dry film, and developing and hardening the photosensitive dry film as a plating resist; (d) copper-plating the inside of the through holes, opened by causing the photosensitive dry film to be dissolved and eliminated, and copper-plating the opening periphery of the through holes; (e) forming a metal protective film for coating the copper-plated area with the metal protective film; (f) separating and eliminating photosensitive dry film; (g) forming a circuit pattern with the copper foil; and (h) performing an overlaying treatment as a post-process to protect the circuit pattern, wherein in the coating, developing and hardening steps, the photosensitive dry film is coated on one side of the outer surface of the substrate made of a laminated sheet of which both sides are coated with copper, and in the copper-plating step, at least the inside of the through holes and the opening periphery of the through holes on one side are copper-electroplated, and in a masking step for coating the other side of the outer surfaces of the substrate with a masking layer is conducted between the copper-plating step and the metal protective film forming step, and a step for eliminating the masking layer is conducted together with the separating step after the metal protective film forming step.