Patent ID: 7994432

Claim:
A circuit wiring board comprising: a wiring substrate; and a heat resistant substrate accommodated in the wiring substrate and having a thermal expansion coefficient in a range between 3 ppm to 10 ppm and comprising a core substrate and a built-up wiring layer formed over the core substrate, the built-up wiring layer comprising a plurality of conductive layers, a plurality of interlayer resin insulating layers and a via hole conductor connecting the conductive layers through one of the interlayer resin insulating layers, wherein the core substrate has a first surface and a second surface on an opposite side of the first surface, the built-up layer is formed over the first surface, and the core substrate has a through hole conductor electrically connecting the built-up layer to the second surface of the core substrate, the heat resistant substrate further comprises a plurality of loading pads positioned to be connected to an electrode of an electronic component on a surface of the built-up wiring board, the through hole conductor is formed in a plurality at a pitch, and the loading pads are positioned a pitch which is smaller than the pitch of the through hole conductors of the core substrate.