Patent ID: 6891732

Claim:
A multilayer circuit board for mounting a semiconductor element thereon, comprising a core substrate of a metal material and a plurality of wiring layers stacked on either side of the core substrate, each of the stacked wiring layers being isolated from an adjacent wiring layer by an insulating layer interposed therebetween, the multilayer circuit board having an area at which a heat spreader for dissipating heat generated from the semiconductor element mounted on the circuit board is to be joined to the multilayer circuit board, wherein the multilayer circuit board is adapted to allow the heat spreader to be joined to the core substrate without the insulating layers being interposed therebetween, the multilayer circuit board having thermal vias piercing through the insulating layers to thereby allow the heat spreader to be joined to the core substrate through the thermal vias, the thermal vias being formed of a material having a thermal conductivity greater than the thermal conductivity of the insulating layers.