HIGH THERMAL CONDUCTIVITY SUBSTRATE

PROBLEM TO BE SOLVED: To solve the problem that a semiconductor element falls in thermal breakdown, since heat generated by the semiconductor element during operation is not efficiently radiated. SOLUTION: The high thermal conductivity substrate 1 is formed by impregnating copper in a sintered porous compact of tungsten powder having a mean grain size of 50-100 μm, not containing grains of 20 μm or less and composed of the sintered porous compact of tungsten 75-95 wt.% and copper 5-25 wt.%. It is used in a package for housing semiconductor elements. This efficiently radiates heat to outside through the base 1, if a semiconductor element 4 generates a lot of heat during operating. Thus the semiconductor element 4 is always at adequate temperatures and operable stably and normally for a long time.