Patent ID: 7038313
Filing Date: 2006-05-02
Classification: H01L

Abstract:
1. A semiconductor device comprising: a circuit board having an insulator substrate and conductor patterns on two surfaces of the insulator substrate, a semiconductor chip bonded to one of surfaces of the circuit board through one of the conductor patterns therebetween, a radiator base bonded to the other of the surfaces of the circuit board through the other of the conductor patterns therebetween for conducting heat generated in the semiconductor chip toward an outside radiation device located at a side opposite to the other of the conductor patterns, and a Pb-free solder layer for connecting the radiator base to said other of the surfaces of the circuit board, wherein said radiator base is formed of a material having anisotropic thermal conductivity so that the radiator base has thermal conductivity in a thickness direction perpendicular to a bonding plane between the radiator base and the circuit board higher than that along the bonding plane, said material of the radiator base being selected such that thermal expansion coefficient of the radiator base is equal to or less than that of the insulator substrate and difference of the thermal expansion coefficient between the radiator base and the insulator substrate along the bonding plane is less than a predetermined value to prevent the solder layer from being broken by thermal stress created between the radiator base and the circuit board.