Semiconductor mounting device and method for manufacturing semiconductor mounting device

A method for manufacturing a semiconductor mounting device, comprising:

• forming a plurality of first bumps on a first substrate;
• forming a plurality of second bumps configured to mount a semiconductor element on a surface of a second substrate;
• and
• connecting the first substrate and the second substrate via the first bumps,
• wherein the first substrate has 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, the second substrate has 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, the plurality of first bumps is formed on an outermost first conductor layer of the first conductor layers formed on an outermost first insulation layer of the first insulation layers, the plurality of second bumps is formed on an outermost third conductor layer of the third conductor layers formed on an outermost second insulation layer of the second insulation layers, 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, and the buildup layers are formed on the surfaces of the core substrate and the second conductor layers, respectively.