PURPOSE: To prevent the malfunctioning of an element without obstructing thermal diffusion by making an insulating layer between an electrode plate, on which a signal input terminal of a power element is fixed, and a thermal diffusion substrate thicker than a section, on which another signal terminal is fast stuck, and a section between the thermal diffusion substrate and a holding plate.
CONSTITUTION: The thickness ta of an insulator 61b on which the electrode plate 66', on which a base terminal 89a is attached, is placed is made larger than the thickness bo of an insulator 61a between the thermal diffusion substrate 62 and the holding plate 60, capacity per a unit area between the substrate 62 and the electrode 66' is made smaller than that between the substrate 62 and the holding plate 60, and thermal resistance per the unit area is increased. A diode 64, a capacity 72 and a resistor 75 are each formed on insulators 61d, 61c, the thickness tb, tc is selected with their relations ta>tb and ta>tc are formed, and radiation is improved. Base and emitter terminals 89a, 89b are fitted to the electrode plates 66', 66", and mechamical strength is held therein. According to this constitution, parasitic capacity can be minimized without hindering radiant property, and the device, which does not cause malfunctioning such as an arm short circuiting while the radiation thereof is excellent, is obtained.
KAWAMATA SHIYOUICHI
KURIHARA YASUTOSHI
ENDOU TSUNEHIRO
TAJIMA FUMIO
MIYASHITA KUNIO
