Werkwijze tot het vervaardigen van vermogengelijkrichters uit silicium.

摘要

988,252. Semi-conductor devices. STANDARD TELEPHONES & CABLES Ltd. Aug. 25, 1961 [Aug. 30, 1960], No. 30749/61. Heading H1K. In a method of manufacturing a semi-conductor device involving the steps of etching selected portions of the surface of a PN junction-containing element and of subsequently soldering on at least one contact, those parts of the surface of the element not required to be etched are masked with the soldering metal to be used in the subsequent soldering process, the soldering metal either being inherently immune to or being passivated against attack by the etchant. The manufacture of a silicon diode is described. One end of a stranded conductor 1 of copper, silver, or silver-coated copper is inserted into a ring of the same material which is compressed and heated so that a solid block 3 is formed at the end of the wire. (Alternatively, the strands of the conductor may be consolidated by melting or soldering them together.) The solid end of the wire is coated with a layer 4 of a soldering metal such as lead (or lead containing 5% of silver). The solder-covered end of the conductor is pressed against a silicon body 5 and heated in an inert or reducing atmosphere (e.g. N 2 /H 2 ) to solder the conductor to the wafer, a flake 6 of solder being simultaneously applied to the opposite face of the body. Jigs may be used to limit the spread of solder during the process. (The end of the conductor need not be precovered with solder. The conductor may be held against a wafer of solder in contact with the body and the conductor joined to the body in one operation.) The diode is now etched to remove the surface semi-conductor material around the junction, solder layer 6 acting as a mask during the process. A mixture of nitric, hydrofluoric, and acetic acids may be used. To avoid dissolution of even trace quantities of lead during etching, the diode may be dipped before etching into hydrochloric acid to form a protective chloride layer or solder layer 4 and 6. (The flexible part of the connecting lead may be protected by a plastic hose during these steps.) The remaining exposed portion of the semi-conductor body is protected with a lacquer coating 8 and the diode is soldered into its casing 9 which serves both as a connector and as a heat dissipation during operation. The diode is soldered to the casing by a comparatively low melting alloy formed from part of solder layer 6 and a layer of tin previously provided on the casing.