SE359406

1,268,978. Making electrical contacts; work guides. BUNKER-RAMO CORP. 31 March, 1970 [14 April, 1969], No. 15061/70. Headings B3A and B3W. [Also in Divisions C7 and H2] An electrical contact is made by forming spaced apart locating pilots in a metal tape 24, selectively coating the tape 24 which resist material so as to form regularly recurring non- coated areas 40, plating a non-corrosive metal on to the non-coated areas 40 of the tape 24, removing the resist material and punching and forming the tape to form individual contacts, each having a plated wear area adapted to engage a similar wear area on another contact. A cadmium bronze tape 24 is passed through a punching press (22), (Figs. 2 and 4, not shown), where pilot holes 25 are formed by a punch (26b). The tape 24 is currently positioned by a side guide (26c) and a locating pin (26a) engaging a previously formed hole. Alternatively, the tape 24 may be provided with printed or embossed areas adapted to be sensed in subsequent processing steps. After cleaning the tape at (30), it is selectively coated with printing ink by rollers (34), (Fig. 5, not shown), so as to form non-coated areas 40, the ink being dried at (36). The holes 25 in the tape 24 are engaged by projections (38) on the rollers (34) so as to precisely locate the bare areas 40. The tape is next passed beneath cleaning nozzles 41 and into a plating tank 47 containing an anode 48 and supplied with a potassium gold cynanide electrolyte from a reservoir 52 whereby the bare areas 40 are plated with gold having a thickness of 30 micro inches. If a relay 53 detects the absence of plating current, the electrolyte is drained into a container 53A to prevent the cadmium in the tape dissolving in the gold solution. The printing ink is subsequently removed by spray nozzles 44, downstream of which the plating power supply is connected to the cleaned tape 24. After plating, the area of each contact member is precisely located in a punch press 56 and the contacts formed and separated from the tape by dies 57. The contact is formed with a protuberance (20), (Fig. 1, not shown). The contacts are finally electrolessly plated with gold to a thickness of 2-5 micro inches.