Patent ID: 8735739

Claim:
A wiring board, comprising: an insulation layer; a buildup structure formed on the insulation layer and comprising a plurality of buildup insulation layers, wherein the insulation layer and the buildup structure form a board structure; a cavity portion formed in the board structure and having an opening on a surface of the buildup structure opposite to the insulation layer, the cavity portion extending through at least one of the buildup insulation layers in the buildup structure to a first depth such that the cavity portion has a bottom surface and a wall surface, the cavity portion comprising: a groove portion formed on the bottom surface of the cavity portion along the wall surface of the cavity portion such that the bottom surface of the cavity portion extends to a second depth recessed from the first depth at the groove portion; and a pad formed on the bottom surface of the cavity portion in a position which is farther from the wall surface of the cavity portion than a position of the groove portion.