Patent ID: 8686300

Claim:
A printed wiring board comprising: an outermost resin insulation layer having a first surface and a second surface on an opposite side of the first surface, the outermost resin insulation layer having a plurality of conducting structures provided in an electronic component mounting region, wherein each conducting structure extends from the first surface to the second surface and comprises: an opening for a first via conductor, wherein the opening has a surface diameter at the second surface; a pad formed on the first surface of the resin insulation layer and configured to mount an electronic component; a first conductive circuit formed on the second surface of the resin insulation layer; and a first via conductor formed in the opening and connecting the pad and the first conductive circuit, the first via conductor having a contacting portion where the via conductor contacts the pad, said contacting portion being located between the first and second surfaces of the outermost resin insulating layer, the via conductor having a contact diameter at the contacting portion which is smaller than the surface diameter of the opening at the second surface, wherein the pad comprises an embedded portion embedded in the outermost resin insulation layer and a protruding portion protruding beyond the first surface of the outermost resin insulation layer, and the embedded portion has an external shape which is greater than an external shape of the protruding portion such that an upper surface of the embedded portion is left exposed by the protruding portion and the upper surface of the embedded portion is axially recessed from the first surface of the resin insulating layer; at least one insulation layer positioned underneath the outermost resin insulation layer and having a stacked via conductor extending through the insulating layer and which is aligned with one of said first via conductors to form a stacked via structure with said one of the first via conductors, said stacked via conductor being centered in said component mounting region.