Patent ID: 7304377

Claim:
A package substrate comprising: a device mounting layer made of resin in which a conductive portion is formed on a device mounting surface; circuit devices mounted on said device mounting surface and electrically connected to said conductive portion; a substrate connecting layer made of resin in which external connecting terminals connected to a mounting substrate are formed; at least one function layer made of resin which is provided between the device mounting layer and the substrate connecting layer and in which predetermined circuit patterns and wirings are formed; and at least one throughhole which is formed from the device mounting layer through the function layer to the substrate connecting layer in a penetrating manner with open stubs and which electrically connects said predetermined circuit patterns to each other; and first electrical connection between the conductive portion on said device mounting surface and the predetermined circuit patterns, second electrical connection between the conductive portion on said device mounting surface and the external connecting terminals, third electrical connection between the predetermined circuit patterns and the external connecting terminals, and fourth electrical connection between the predetermined circuit patterns being achieved only by the use of said throughhole formed from the device mounting layer through the function layer to the substrate connecting layer in the penetrating manner.