Patent ID: 7183497

Claim:
A multilayer wiring board including solder having a solder reflow temperature and comprising: a core substrate having a thickness direction, a first principal plane and a second principal plane, and a plurality of through-holes, each comprising a penetration hole including an inner wall and having a diameter of no greater than 200 μm and opening at the first principal plane and second principal plane and a through-hole conductor provided on the inner wall of the penetration hole; an interlayer insulating layer disposed at least on one side of at least one of the first principal plane of the core substrate and the second principal plane of the core substrate; a wiring layer disposed on the surface of the interlayer insulating layer; a hardened filling material filling the through-holes and having a thickness direction; and a lid conductor closing at least one end of the through-holes, wherein the hardened filling material has a value of linear expansion that is no greater than 1.2% in a temperature region from room temperature to the solder reflow temperature and a mean coefficient of thermal expansion in the thickness direction of between 20 ppm/K and 40 ppm/K and wherein the core substrate has a mean coefficient of thermal expansion in the thickness direction of a value such that the absolute value of the difference between the mean coefficient of thermal expansion of the hardened filling material and the core substrate is no greater than 20 ppm/K.