Strain gauge mfr. by vacuum vapour deposition - ensures measurement bridge null point stability with low resistance drift

摘要

A method of mfg. a strain gauge by vapour deposition on a substrate in a vacuum is designed to ensure null point stability of the bridge arrangement in which such a gauge is used by achieving a low resistance drift. After a predefined resistance of the strain gauge is achieved, an inorganic electrically non-conducting covering is applied. An oxidising atmosphere is formed inside the vacuum chamber under control dependent on the gauge resistance. The press. in the chamber is maintained at 5 x 10-5 torr by controlled oxygen input. The deposited material is placed in a vapouriser and the substrate is suitably masked.