Semiconductor rectifier device

847,179. Semi-conductor rectifiers. WESTING- HOUSE ELECTRIC CORPORATION. Aug. 1, 1958 [Aug. 9, 1957], No. 24847/58. Class 37. A rectifier device as shown in Fig. 2 comprises a semi-conductor rectifier cell 1 soldered to a flat base 7 of any suitable material, preferably copper, by a solder, preferably of 95 % lead and 5 % indium, the base 7 is mounted within a substantially cup shaped member 8 with which it is preferably integral. The base 8 has a passageway 11 and tube 9 for evacuating the sealed enclosure. The base 8 is attached preferably by soldering with a 100% tin solder, to a heat dissipating means which may be water cooled or, as shown in Fig. 2, be a relatively massive cylindrical portion provided with radial cooling pins. On the other side of cell 1 a conductor 17 is attached in an enclosure formed by ring 16 attached to the top electrode of cell 1, a solder 95% lead and 5% indium being used. The conductor 17 comprises a heavy multistrand twisted copper cable in order to provide flexibility between the semi-conductor cell and the enclosure. The top of the conductor is cold welded to a cup 19 of soft oxygen free copper which is silver brazed to a sleeve 20 preferably of "Kovar" (Registered-Trade Mark) formed with a re-entrant portion in order to absorb mechanical deformation. This sleeve is fused to a glass tube 21 which is fused to a second tube of Kovar which completes the sealed enclosure around the semi-conductor cell by being projection welded to the base 8. The cooling radiator is coaxially mounted on a reduced diameter of the cup 19 preferably by being soldered by a 100% tin solder. The radiator extends down over the glass seal 21 in order to protect it from mechanical damage and a lead 25 is soldered to the radiation for external connection. Semi-conductor cell, comprises a slice of N type silicon, or germanium, with a layer of aluminium, or indium, alloyed to the upper surface and having an upper support plate, preferably of tungsten or molybdenum bonded to the surface by the alloying material. The lower surface of the slice is also supported by a similar plate soldered to the semi-conductor material by a silver alloy if the material is silicon or by pure tin solder if the semi-conductor is germanium.