Patent ID: 8022532

Claim:
An interposer to be provided together with a semiconductor chip in a semiconductor device and, when the semiconductor device is mounted on a mount board, disposed between the semiconductor chip and the mount board, the interposer comprising: an insulative substrate of an insulative resin; an island provided on one surface of the insulative substrate to be bonded to a rear surface of the semiconductor chip via a bonding agent; a thermal pad provided on the other surface of the insulative substrate opposite from the one surface in generally opposed relation to the island with the intervention of the insulative substrate; thermal vias extending through the insulative substrate from the one surface to the other surface to connect the island to the thermal pad in a thermally conductive manner; metal terminals formed on the other surface of the insulative substrate; and connection vias, being different from thermal vias, extending through the insulative substrate from the one surface to the other surface to be connected to the metal terminals respectively, wherein the thermal vias include a first thermal via having a relatively-large diameter and a second thermal via having a relatively-small diameter, and each of the connection vias has a diameter that is smaller than the diameter of the first thermal via and larger than the diameter of the second thermal via.