Patent ID: 7371615

Claim:
A method for producing a heat sink for cooling a semiconductor device, comprising the steps of: forming plural base members, the base member being each in plate or block-shape, the base member each having paths shaped on one or both sides of surfaces thereof, and the base member each having connecting regions on one or both sides of surfaces thereof; coating a coating layer of Au onto the base members; putting a solder of Sn or Au—Sn alloy onto connecting regions, the connecting region being coated with the coating layer of Au; assembling the base members together such that the base members are bonding to each other at the connecting region and the paths shaped on each of the surfaces of the base members form a communicating flow path for a cooling medium inside the bonded base members; and heating to diffuse Sn from the solder of Sn or Au—Sn alloy into the coating layer of Au, and to make a bond layer of alloy containing at least 91 wt % of Au and at most 9 wt % of Sn, the bond layer being interposed between connecting regions to which the base member each connects.