| 摘要 |
777,985. PN junction rectifiers. WESTING- HOUSE ELECTRIC INTERNATIONAL CO. Jan. 7, 1955 [Jan. 14, 1954], No. 539/55. Class 37. A rectifier for handling currents of the order of hundreds of amperes comprises a wafer 2 of germanium or silicon of one conductivity type but with a surface layer of opposite conductivity type a first molybdenum plate 6 secured in good thermal and electrical. contact with said layer and a second molybdenum plate 3 similarly secured to the opposite face of the wafer. In the embodiment (Fig. 1) a wafer 2 of N type Ge is soldered to molybdenum plate 3 with pure tin or tin lead with or without donor impurities such as antimony and phosphorous and plate 6 is soldered on with indium 5 which produces a PN junction within the semiconductor. Aluminium may be used in place of indium with silicon. Alternatively a wafer of P type material may be used and molybdenum plate 6 may be secured via a layer 5 of donor material such as antimony. Encasing and cooling. The rectifier may be hermetically enclosed in a glass cylinder with metal ends to which the electrical connections are made. One of the molybdenum plates may be secured to a water-cooled end wall of the casing and the other molybdenum plate may be connected to the other end wall by a flexible lead, Fig. 2 (not shown), or by a water-cooled cylinder 40, Fig. 3, extending through and brazed to a casing end member 33 and having a flexible connecting strip 46. In an air-cooled modification, Fig. 4 (not shown) one end of the casing to which one of the rectifier molybdenum plates is directly secured is provided with a copper block and cooling fins and the other side of the rectifier is connected via a flexible lead to a metal tube which projects through the opposite end of the casing and has further cooling fins. This tube is used as a terminal and for filling the casing with a suitable gas. In another modification, Fig. 5, specially suitable for building into a stack, the casing is a ceramic ring soldered to enlarged end plates 63, 66. Further cooling fins are provided at 64 and the space is filled with an inert gas through a pipe 68. The flexible connection between the rectifier element and the upper plate is by way of flexible diaphragms 67. |
