HEAT SINK, SEMICONDUCTOR PACKAGE AND SEMICONDUCTOR MODULE

Provided is a heat sink having a clad structure of Co-Mo composite materials and Cu materials, satisfying high heat-sink properties required of the heat sink for use in a semiconductor package with a frame on which a high-output and small-sized semiconductor is mounted, and preventing, when applied to the semiconductor package with a frame, crack of the frame due to local stress concentration. The heat sink has three or more Cu layers and two or more Cu-Mo composite layers alternately stacked in a thickness direction so that the Cu layers are outermost layers on both sides thereof, the Cu layers as the outermost layers each having a thickness t1 of 40 μm or more, the heat sink satisfying 0.06≤t1/T≤0.27 (where T: heat sink thickness) and t2/T≤0.36/[(total number of layers−1)/2] (where t2: Cu-Mo composite layer thickness, the total number of layers: sum of numbers of Cu layers and Cu-Mo composite layers).