Heat sink substrate consisting essentially of copper and molybdenum and method of manufacturing the same

A Cu—Mo composite heat sink substrate, consisting essentially of a Cu—Mo composite substrate which is formed by impregnating melted copper (Cu) into a molybdenum (Mo) green compact and which is given in the form of a rolled plate obtained by rolling the Cu—Mo composite plate in a rolling direction after impregnation, the rolled plate comprising 40-60 wt % of Cu and exhibiting characteristic anisotropy,

• said characteristic anisotropy of the rolled plate being specified by a difference between the thermal expansion coefficient in a direction parallel to the rolling direction and that perpendicular to the rolling direction;
• the difference between the thermal expansion coefficients being not greater than 8%;
• the Cu∫Mo composite substrate being made from the Mo green compact which comprises a mixture of copper powder not greater than 5 wt % and the balance of molybdenum.

A large area heat sink substrate semiconductor device, the heat sink substrate consisting essentially of a single layer composite material composed of copper and molybdenum and having a thermal conductivity of at least 200 W/m·K and a thermal expansion coefficient of 12×10−6/K or less within a temperature range of from room temperature to 200° C.;

• the heat sink substrate exhibiting characteristic anisotropy of thermal conductivity and thermal expansion coefficient in a substrate surface direction thereof;
• the characteristic anisotropy being specified by a difference of 12% or less between the lengthwise direction and the lateral direction of the thermal conductivity and by another difference of 8% or less between the lengthwise direction and the lateral direction of the thermal expansion coefficient.