Patent ID: 8586875

Claim:
A wiring board, comprising: a substrate having a first surface and a second surface on an opposite side of the first surface, the substrate having a first penetrating hole penetrating through the substrate between the first surface and the second surface, a first through-hole conductor formed on an inner wall of the first penetrating hole, a filler filled inside the first through hole conductor and forming a second penetrating hole in the first penetrating hole, and a second through-hole conductor formed in the second penetrating hole; a first conductive circuit formed on the first surface of the substrate comprising a metal foil layer; a second conductive circuit formed on the second surface of the substrate comprising a metal foil layer; a first conductive portion formed on one end of the second penetrating hole; and a second conductive portion formed on an opposite end of the second penetrating hole, wherein the first through-hole conductor is connecting the first conductive circuit and the second conductive circuit, the second through-hole conductor is connecting the first conductive portion and the second conductive portion, the first conductive circuit has a thickness which is set greater than a thickness of the first conductive portion, the second through-hole conductor comprises a conductive material deposited in the second penetrating hole, the first and second conductive portions integrally include the conductive material of the second penetrating hole, the first conductive circuit comprises a first electroless plated layer, a first electrolytic plated layer, a second electroless plated layer and a second electrolytic plated layer formed on the metal foil layer of the first conductive circuit, the second conductive circuit comprises a first electroless plated layer, a first electrolytic plated layer, a second electroless plated layer and a second electrolytic plated layer formed on the metal foil layer of the second conductive circuit, the first conductive portion formed on the one end of the second penetrating hole comprises an electroless plated layer and an electrolytic plated layer, the second conductive portion formed on the opposite end of the second penetrating hole comprises an electroless plated layer and an electrolytic plated layer, and the conductive material of the second through-hole conductor comprises an electrolytic plated metal forming the electrolytic plated layers of the first and second conductive portions.