| 摘要 |
881,833. Semi-conductor devices. WESTERN ELECTRIC CO. Inc. Feb. 28, 1958 [March 1, 1957], No. 6529/58. Class 37. A method of making a semi-conductor device comprises applying to a base assembly on which is mounted a PN-junction body a metallic cover-plate, the base assembly or cover-plate including a protuberant part to engage the body, and applying pressure and heat to the coverplate to bind it to the assembly and to press the protuberant part against the body to form an ohmic contact therewith. In the embodiment (Fig. 2) a forged base 12 of nickel, washers 14 and 15 of brazing materials, e.g. silver-copper eutectic, silver, copper, or nickel, containing titanium, an alumina or steatite annulus 13 , and nickel washer 16 are assembled as shown, heated to 980‹ C. and then rapidly cooled in argon to form a sub-assembly. A monocrystalline PN or PNPN-junction silicon element 11 is placed within the raised margin 18 on the gold-coated protuberance 19. A shaped nickel cover member 17 gold plated on its lower face is then mounted on top of the subassembly and its periphery pressed into contact with washer 16 so that the pressure at point 20 is 30,000 lbs./sq. inch for ¢-5 minutes while the assembly is heated to 310-325‹ C. The process results in thermo-compression bonds being formed between the gold layers 17, 26 and element 11 and between the edges of cover member 17 and the washer 16. As an alternative the cover may be cold welded or resistance welded to the washer in which case the gold layers are merely in pressure contact with the element 11. The cover member is so designed that in the finished device, in spite of manufacturing tolerances in other parts of the assembly, the pressure exerted on the semiconductor element is constant and independent of dimensional changes likely to arise in operation. This is effected by stressing the member beyond its elastic limit. Specification 881,832 is referred to. |
