JPS56112665A - Selecting method for insulated cylindrical package type semiconductor device - Google Patents

Abstract

PURPOSE:To make it possible to detect and to remove the insulated cylindrical package type semiconductor device in which some conductive foreign matters are sealed, by making use of high electric field. CONSTITUTION:Between a wire electrode 22 which is connected to a DC high voltage generating circuit 21 and a flat earthed electrode 23 which faces the wire electrode 22, an insulated cylindrical package type semiconductor device consisting of an insulated cylindrical package 10 and a semiconductor device 6 is placed and connected to the DC power source 24. By driving the DC high voltage generating circuit 21, a high electric field is developed between the wire electrode 22 and the flat earthed electrode 23 and it is applied to the semiconductor device 6 through the cathode and anode radiation electrodes 8, 9. By so doing a highly concentrated electric field is generated in the peripheral part of the N type semiconductor layer 2, and if any conductive foreign matters DELTA are sealed inside the insulated cylindrical package 10, they are attached between the peripheral part of the N type semiconductor device 2 and the anode radiation electrode 9 because of the concentrate electric field, and a heavy current flow from the DC power source 24 to the conductive foreign matter A, and the function of the P<+>-N junction J of the semiconductor device 6 is deteriorated or damaged.