Patent attributes
A wiring substrate is manufactured by attaching an adhesive protective film to a metal-foiled laminate sheet, forming bottomed via holes by partially removing the film and an insulating film, filling conductive pastes into the holes, and peeling the film. A wiring substrate is manufactured by forming an adhesive protective layer so as to cover a patterned metal foil on a metal-foiled laminate sheet, forming bottomed step via holes by partially removing the layer and an insulating film, filling conductive pastes into the holes, and peeling off a protective film. The wiring substrate and the second wiring substrate are laminated in such a way that protruding parts of the pastes come into contact with respective protruding parts of the pastes.
