Heat dissipation component for semiconductor element

To provide a heat dissipation component for a semiconductor element, said component being endowed with high thermal conductivity and a coefficient of thermal expansion approximating that of the semiconductor element, and said component not experiencing swelling or cracking under conditions of actual use. Provided is a heat dissipation component for a semiconductor element, said component characterized in being equipped with a composite part that contains 50-80 vol% of diamond powder, the particle diameter volumetric distribution thereof having a first peak at 5-25 [mu]m and a second peak at 55-195 [mu]m, the ratio of the area of the 1-35 [mu]m particle diameter volumetric distribution and the 45-205 [mu]m particle diameter volumetric distribution being 1:9 to 4:6, the balance of the composite part comprising an aluminum-containing metal, both principal surfaces of the composite part being provided with a surface layer containing at least 80% by volume of an aluminum-containing metal and measuring 0.03-0.2 mm