| 摘要 |
1494394 Selective gold electro-plating WESTERN ELECTRIC CO Inc 19 Feb 1975 [19 Feb 1974(2)] 7091/75 Heading C7B [Also in Division H1] A composite surface comprising regions of Ti and regions of Pt, Pd and/or Au is selectively gold electro-plated on the latter by controlling the cathodic potential of the surface below that at which gold deposition occurs on the Ti, by which is meant less than 50000 Au nucleation sites per cm<SP>2</SP> on the Ti. Conventional baths are used, with optionally 20 ppb to 2 ppm of Pb present. Details of plating onset potentials for Pd, Pt and Au in relation to Ti are given, and control may be effected via a calomel electrode and potentiostat, although two-electrode systems are possible. The potential may be increased stepwise or continuously during plating. The Ti may be a layer on a conventional semi-conductor substrate, e.g. based on Si, and bear a printed circuit pattern of the Pt, Pd and/or Au. It may optionally be protected with a photo-resist during plating. |
