GB570158A - - Google Patents

Abstract

570,158. Inductances. STEVENS, R. J., and BURNHAM, T. H. Oct. 25, 1943, Nos. 17522 and 17523. [Class 38 (ii)] [Also in Group XXXVI] Electrical components such as inductances employ thin metallic films obtained by depositing, for example, by electro-deposition, a coating of the metal which is to form the film, upon a thin sheet of a dissimilar metal and then dissolving the latter so as to leave the film floating on the surface of the dissolving liquid. To facilitate removal of the film, the liquid has added to it a little ethyl or higher alcohol to reduce the surface tension, or the film may be transferred by a sheet of glass to a tensionreducing liquid bath. To facilitate its eventual adhesion to a carrier or backing, such as a rod, the foil is passed to a bath containing isinglass and a preservative such as formaldehyde. After application to its support, the film may be further treated electrolytically to alter its thickness throughout or at localized zones, such as for building up terminals. A helical cut may be made in the film to leave a helical conducting covering on the support. In obtaining gold foil, the gold is plated on to a copper foil which is then treated with silver nitrate to replace the copper with silver, which is then dissolved in nitric acid. Other metals referred to are silver, lead and bismuth. Suitable materials for the supports are porcelain, glass and plastics of the phenolic, urea, or cellulose acetate types.