PURPOSE: To obtain a semiconductor device having very high voltage resistance in a structure containing an exposed pn-junction surface by coating an insulating film on the pn-junction surface, then containing the semiconductor device in an airtight metal box, and sealing the box with highly insulating gas.
CONSTITUTION: In a thyristor having a structure that the end of a pn-junction is exposed with moat, the moat is coated with an insulating film 51 made of glass film, Si3N4 film, Al2O3 film, PSG film, etc. to protect the exposed pn-junction surface. This device is normally molded with resin, but the dielectric strength of the device is increased without resin. That is, an anode electrode 9 having larger area than the device is fixed to the back surface of the device, and an airtight sealing metal box 53 is welded using the end extended from the electrode 9. Then, the box is evacuated thermally to vacuum, inert gas 52 such as Ar, N2 is filled in the box, and the box is sealed airtightly. Thus, no segregation due to DC electric field with ion in an organic material occurs, and its leakage current may not be increased.
ISHIKAWA EIICHI
MIYASHITA TAKAO
MISAWA YUTAKA
