Semiconductor fabrication

924,209. Semi-conductor devices. PHILCO CORPORATION. May 7, 1959 [May 7, 1958], No. 15686/59. Class 37. A semi-conductor device is mounted in an hermetically sealed easing by means of a body of good heat-conducting properties fastened to the enclosure. Fig. 6 shows an exploded view of a transistor and its housing before assembly. A wafer 18 of semi-conductive material has an alloy emitter contact 19 and a ring-shaped base electrode 17 on one face and an alloy collector contact 20 on the rear face. The semi-conductor device is supported by a nickel-plated silver stud 23 which is soldered to the collector electrode. The stud is then held in a chuck to facilitate soldering of leads 21, 22 and is cleaned by etching and baked to volatilize extraneous matter. The stud-mounted assembly is then cold welded to nickel-plated ring 27 to ensure good heat conductivity from the collector junction to the housing. Lugs 29 on this ring locate it accurately on the lower part 13 of a housing for the device. This part of the housing has connection 15 passing through glass insulation in the base. Collector connection 15 passes through hole 301. Filaments 21, 22 are now welded to their leads. The top and bottom members 13, 12 are then pressure welded to each other sandwiching ring 27 as described in Specification 869,934. A further baking process may precede the welding. Fig. 7 shows a modification in which the emitter is supported by a strip 33 of rectangular crosssection the end of which is sandwiched between the two parts of the housing. A rectangular frame base 37 connects to base lead 39. A screwed stud may be welded to the housing to facilitate mounting. Fig. 9 (not shown) shows such an arrangement mounted on the magnetic yoke of a loud-speaker.