Patent ID: 8643154

Claim:
A semiconductor mounting device, comprising: a first substrate comprising a plurality of first insulation layers, a plurality of first conductor layers formed on the first insulation layers, and a plurality of via conductors connecting the first conductor layers; a second substrate comprising a core substrate, a plurality of second conductor layers, a plurality of through-hole conductors and a plurality of buildup layers comprising a plurality of second insulation layers and a plurality of third conductor layers; a plurality of first bumps connecting the first substrate and the second substrate and formed on an outermost first conductor layer of the first conductor layers formed on an outermost first insulation layer of the first insulation layers; and a plurality of second bumps positioned to mount a semiconductor element to the second substrate and formed on an outermost third conductor layer of the third conductor layers formed on an outermost second insulation layer of the second insulation layers, wherein the second substrate has a thickness which is greater than a thickness of the first substrate, the second conductor layers are formed on opposite surfaces of the core substrate, respectively, the through-hole conductors are formed in penetrating holes through the core substrate and connecting the second conductor layers to each other, the buildup layers are formed on the surfaces of the core substrate and the second conductor layers, respectively, and the via conductors in the first substrate are stacked over and make contact with one another such that the via conductors form a plurality of columnar structures.