| 摘要 |
912,554. Glass-to-metal seals. PACIFIC SEMICONDUCTORS Inc. March 4, 1960, No. 7848/60. Class 36. In the manufacture of diode bodies consisting of a pair of metal tubes 12 spaced by a sealed-on glass sleeve 13, manufacturing tolerances between the glass and metal, which interfere with the normal R.F. heating process, are accommodated by a presealing step consisting of quickly heating to a temperature slightly above the softening-point of the glass, quickly cooling below this temperature, and slowly cooling through the annealing range of the glass. During this process the glass shrinks on to the metal tubes and produces an imperfect " black " seal, the metal tubes being covered with a black oxide. Subsequent R.F. heating produces a " grey " hermetic seal. The tubes 12 may be of " Kovar " (Registered Trade Mark) and the sleeve 13 of a hard boro-silicate glass, e.g. 80 % silicon, 14% boric oxide, 4% soda, and 2% alumina. For the pre-sealing treatment, the bodies are threaded on to a series of nickel-chromium alloy wires 11 supported on brackets 25, 26 in a nickel boat 18. The boat is placed for 80- 90 seconds in a preheated oven and then quickly moved to a box of insulating material, e.g. asbestos, in which it quickly cools below the softening-point of the glass. Thereafter, it cools through the annealing range over about 15 minutes. For the final sealing process, each body is placed on a mandrel 44 by means of tongs 40. This mandrel is spring-biased upwards and is depressed to carry the body into the R.F. coil 45 by a complementary mandrel 43. |
