| 摘要 |
1,162,390. Semi-conductor devices. PHILIPS ELECTRONIC & ASSOCIATED INDUSTRIES Ltd. 12 Dec., 1966 [15 Dec., 1965], No. 55524/66. Heading H1K. [Also in Division C7] An ohmic contact to a body of N-type oxidic ceramic consists of a chromium-(nickel and/or cobalt) layer (which may contain up to 10% of other metals) with a chromium content of not less than 50 weight per cent and a superposed layer of a solderable material such as silver or nickel. The semi-conductor for PTC resistors may be titanium dioxide doped with an oxide of tungsten or niobium; barium or barium-strontium titanate doped with lanthanum oxide; or as in the examples BaTi 1À0175 O 3 +0À15 mol. per cent Sb 2 O 3 or Ba 0À7 Sr 0À3 Ta 1À0175 O 3 + 0À15 mol. per cent Sb 2 O 3 . For NTC resistors a suitable semi-conductor is (Fe 1-α Tiα) 2 O 3 , α = 0À1-0À3. Voltage dependent resistors may have an ohmic contact as described and a known barrier electrode. The chromium-containing layers may be formed by evaporation from sources low in chromium in view of the high volatility of chromium. Suitable sources are (in weight per cent) Co80Cr20; Ni90Cr10; Ni80Cr20; Ni60Cr40; Ni76Cr15Fe9; and Ni72Cr20Fe5SilÀOMn1À0Ti0.5Cu0.5 The layer of solderable material is formed by deposition in vacuo without exposing the chromiumcontaining layer to air. Leads may be secured to a silver layer with a solder constituted by Sn57 Pb36 Ag7. |
