GB1151658A - Resistors - Google Patents

Abstract

1,151,658. Glass compositions for encapsulating metals. E. I. DU PONT DE NEMOURS & CO. 1 May, 1967 [2 May, 1966], No. 20101/67. Heading C1M. [Also in Division H1] Resistors incorporating palladium or palladium oxide or both and possibly gold, silver or other noble metals are encapsulated in a glaze incorporating a composition containing (A) from 70-99% (by weight) of a glass frit containing either (1) 50-85% PbO, 0-15% CdO, 1-20% B 2 O 3 and 0-15% SiO 2 or (2) 50-70% PbO, 15-45% PbF 2 , 1-15% B 2 O 3 and 1-5% SiO 2 or any mixture of (1) and (2) and (B) from 1-30% of finely divided fused silica, petalite, spodumene or beta eucryptite or any mixture thereof. Component A may also contain as separate additives up to 10% MgO, CaO, TiO 2 , ZnO, SrO, ZrO 2 , SnO 2 , BaO or Bi 2 O 3 and may be used as glass constituents in amounts up to 10% by weight of the glass present. The glass component and component (B) may be ballmilled together or separately and applied to the resistor as a paste by mixing with a vehicle such as water or methyl, ethyl, butyl, propyl and/or higher alcohols, an ester, terpine, a polyterpine resin, a polymethacrylate or ethylcellulose in solvents such as aliphatic petroleum naphtha, terpene and alcohol ethers of ethylene glycol. The vehicle may contain volatile liquids such as kerosene, xylene or toluene, the preferred vehicle being a 5% solution of ethyl cellulose in beta-terpinol. After application by dipping or screen stencilling the encapsulating composition is fired for about two minutes at from 520-510‹ C. The resistor may be printed on a substrate of fosterite, sapphire, steatite, titanium dioxide, alkali earth titanates, zircon, porcelain or alumina. In one example the printed register comprises a 70% inorganic binder, the remaining 30% comprising 50% silver, 47¢% palladium and 2¢% palladium oxide.