| abstract |
1414947 Printed circuits SIEMENS AG 25 Jan 1974 [31 Jan 1973] 03453/74 Heading H1R A thin film metal or alloy circuit structure is provided by vapour depositing a thin continuous layer of metal or alloy on a carrier; applying, exposing, and developing a photoresist lacquer to define the required circuit by exposure of the underlying layer; electrodepositing a thin gold layer thereon; electrodepositing a thicker layer of metal or alloy thereon, removing the photoresist, and removing the exposed parts of the thin metal or alloy layer. A glass or ceramic carrier 1 (Fig. 1) is vapour deposited with a Ni-Fe layer 2 and thereon a photoresist layer 3, in which channels 7 are photographically formed to expose the metal layer. An Au layer 4 (Fig. 2) is electrodeposited on the exposed parts and reinforced by a further Ni-Fe layer 5 overlain by an electrodeposited Au layer 6 as protection. The photoresist is removed, (Fig. 3, not shown), and the carrier is exchange etched in a weakly acidic Au bath to remove the exposed Ni-Fe layer 2 and replace it with Au, which is subsequently etched off in dilute KCN. The process is applicable to production of a magnetostriction free Ni-Fe control circuit for a cylinder domain store, or to microcircuit wiring for integrated circuitry. |