GB1053304A - - Google Patents

Abstract

1,053,304. Metal support formed by stripping coating. SIEMENS & HALSKE A. G. Jan. 30, 1964 [Feb. 4, 1963; April 25, 1963; Oct. 14, 1963], No.4092/64. Headings C7B and C7F. [Also in Division H1] In manufacturing an assembly comprising a non-ferromagnetic metallic base plate having magnetizable material deposited as a thin layer on discrete areas of one face, e.g. by vapour deposition, cathode sputtering, or electroplating, the base plate is formed by depositing a metallic material onto the surface of a carrier having very smooth surfaces, e.g. a polished plate of glass or synthetic material so that the deposit conforms very closely to the carrier surface and subsequently stripping off the metallic layer so formed, and the magnetizable material is deposited on the face of the layer which contacted the carrier surface. Typically a polished optically flat glass plate is rendered electrically conductive on one face by cleaning in a hot aqueous solution of chromic oxide and sulphuric acid, accompanied by ultrasonics, followed by electroless deposition of copper, gold, or silver, and copper is then electroplated over the conductive layer, e.g. from an acid copper bath containing phenolsulphonic acid and a wetting agent at 40‹C. An adhesive foil of synthetic resin is then applied to the copper for stripping it from the glass plate and the smooth copper face is then coated with a 81-19% Ni-Fe alloy by electrolytic or vapour deposition. To form a magnetic memory matrix Fig. 4 (not shown), a photo-sensitive varnish is then employed to make a resist mask by photographic exposure and development, and the unprotected areas etched away electrolytically with a solution of hydrochloric and citric acids, whereafter the remaining varnish is removed with trichlorethylene. Silicon oxide is then vapour-deposited over the magnetic alloy and copper areas, and two layers of conductive strips insulated by silicon oxide are applied so that the strips intersect at right angles over the magnetic elements. In alternate methods of forming the smooth metal face, Figs. 5 to 10 (not shown), a cleaned flat glass plate is subjected successively to solutions of acid aqueous stannous chloride and alcoholic alkaline formaldehyde solution and is then chemically silvered all over with an aqueous ammonia solution of silver nitrate and rochelle salt followed by heating. A thin layer of copper is then electrodeposited from an acid copper bath and the margins and edges are then masked with a bath-resistant tape, whereafter more copper is electrodeposited and the metal is cut through along the edges of the masking tape to free two copper bodies having thin layers of smooth silver. The bodies may then be electroplated with gold containing small amounts of cobalt and indium from a cyanide bath and the magnetic material is deposited subsequently on the face adjacent the silver layer. In another modification Figs. 11 to 13 (not shown) of this method, a further inner border of masking tape is applied to ensure a more uniform deposit of copper at the edges. Reference has been directed by the Comptroller to Specification 992, 368.