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H. Cross Co. is one of the largest suppliers of elliptically shaped etched
molybdenum foil for hermetic sealing of quartz lamps. Etched molybdenum
foil, of all metals, is used since its coefficient of expansion is the
closest to quartz. The elliptical shape produces an air and gas tight lead
into the lamp envelope, thus preventing filament degradation during lamp
operation.
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Etched foil leads are welded assemblies used as the lead wires in many
types of hard glass or quartz encapsulated devices for high temperature
applications. They provide the functions of internal and external
electrical connection and mechanical support, plus a hermetic sealing
capability for pinch seals. Applications include mercury arc lamps,
tungsten-halogen cycle lamps, infrared heat lamps, and certain electronic
and instrumentation applications.
H. Cross Company starts with a very tightly controlled molybdenum wire
made to our own specifications free from inclusions, splits, or
contaminations. It is then rolled very thin without creating pin holes
or leaker lines.
After rolling, the material is electrolytically etched, again under
stringent controls, to arrive at the elliptical shape with the proper
thickness and width to special requirements of each customer. It is then
cleaned, annealed, inspected and spooled for shipment. For best protection
of the sharp edges, the spools of H. Cross Company design are slightly
wider than the ribbon.
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