Power-module substrate with heat-sink

A power-module substrate with heat-sink, comprising:

• a power-module substrate in which a circuit layer made of copper or a copper alloy is disposed on one surface of a ceramic board and a metal layer made of copper or a copper alloy is disposed on the other surface of the ceramic board;
• and
• a heat sink which is bonded on the metal layer of the power-module substrate and formed from an aluminum-impregnated silicon carbide porous body in which aluminum or an aluminum alloy is impregnated in a porous body made of silicon carbide, wherein
• where yield stress of the circuit layer is σ1 (MPa), a thickness of the circuit layer is t1 (mm), and a bonding area between the circuit layer and the ceramic board is A1 (mm2) and yield stress of the metal layer is σ2 (MPa), a thickness of the metal layer is t2 (mm), and a bonding area between the metal layer and the ceramic board is A2 (mm2);
• wherein
• the thickness t1 is formed to be not less than 0.1 mm and not more than 3.0 mm,
• the thickness t2 is formed to be not less than 0.15 mm and not more than 5.0 mm and the thickness t2 is formed to be larger than the thickness t1, and
• a ratio {(σ2×t2×A2)/(σ1×t1×A1)} is in a range not less than 1.5 and not more than 15.