Patent ID: 8729405

Claim:
A wiring board, comprising: a substrate having a first penetrating hole and a plurality of second penetrating holes formed around the first penetrating hole; a first conductive portion formed on a first surface of the substrate and positioned at a first end portion of the first penetrating hole; a second conductive portion formed on the first surface of the substrate and positioned at first end portions of the second penetrating holes around the first conductive portion; a third conductive portion formed on a second surface of the substrate on an opposite side of the first surface and positioned at a second end portion of the first penetrating hole; a fourth conductive portion formed on the second surface of the substrate and positioned at second end portions of the second penetrating holes around the third conductive portion; a first through-hole conductor formed in the first penetrating hole and comprising a conductive material filling the first penetrating hole of the substrate, the first through-hole conductor electrically connecting the first conductive portion and the third conductive portion; a plurality of second through-hole conductors formed in the second penetrating holes and comprising a conductive material filling the second penetrating holes, the plurality of second through-hole conductors electrically connecting the second conductive portion and the fourth conductive portion; and a second through-hole structure comprising a third through-hole conductor and a plurality of fourth through-hole conductors formed around the third through-hole conductor, wherein the substrate includes a reinforcing material having portions protruding into the first through-hole conductor and second through-hole conductors, respectively, the first through-hole conductor and second through-hole conductors form a first through-hole structure, the first through-hole conductor in the first through-hole structure is electrically connected to the plurality of fourth through-hole conductors in the second through-hole structure, and the second through-hole conductors in the first through-hole structure are electrically connected to the third through-hole conductor in the second through-hole structure.