PURPOSE: To perform heat radiation from a semiconductor pellet with extremely good efficiency, by providing a heat exchanging tube as a metallic electrode for taking out current.

CONSTITUTION: A heat compensating plate 2 of tungsten is soldered and fixed to the center of the upper surface of a copper base 1 serving as an anode metallic electrode and radiator, and further, the surface of the anode electrode of a thyristor 3 is soldered on the upper surface thereof. The heating part 4a at one end of the heat exchanging tube 4 is soldered on the surface of the cathode electrode of the thyristor 3 with a cathode lead 5 mounted on the heating part 4c at the other end extended through the fitting part of the radiating fin of the heat exchanging tube 4 by a screw. The thyristor 3 is surrounded by the side walls 7 of the case of an insulator 6 being airtight-sealed. Thus, the heat generated in the thyristor 3 is radiated with good efficiency from the radiating fin 4d on the outside of the heat exchanging tube 4 as a metallic electrode for taking out the current of the cathode electrode.