GB1002358A - Improvements in and relating to the manufacture of electrical components by coating of metal on to an insulating substrate - Google Patents

Abstract

Electrical circuit components e.g. resistors, are made by depositing a layer of a first metal on an insulating substrate e.g. heat-resisting glass, preferably by sputtering, and then a further layer of a second metal, part of which is subsequently removed. The first metal may be Ta, W, Ti, Cr, Mo, or nichrome, and is of higher electrical resistance than the second metal e.g. Au, Pt group, Ir, Ag, Ni, Al, and Cu. For example, glass is sputtered cathodically with a layer of Ta, and then similarly coated with Au, both steps being effected in vacuum or in argon gas. A photo-sensitive resist is applied, and a desired pattern formed using U.V. light and a photographic negative as stencil. The unexposed resist is removed, and the exposed gold pattern etched to expose the Ta layer the exposed resist layer being protected by heating at 135 DEG C.; alternatively the Ta layer may also be removed, the exposed resist removed and a further pattern formed on the remaining gold layer, which is again etched to expose the lower gold layer. A copper mask may be used by applying it to the substrate and sputtering the Ta and Au layers through the mask which is then dissolved away. An apparatus is described in which the heated substrates are in turn brought under the separate sputtering zones. A resistor is also illustrated of a tantalum strip coating on glass with thick gold conductor tabs of low resistance.