| 摘要 |
A magnetic metal is plated on to one surface of a web of dielectric material by electrolessly depositing a metallic film on all surfaces of the web and then moving the web through a bath containing an electrolyte, an anode and a cathode at least partially submerged in the electrolyte, the web being maintained in tight contact with the cathode so as to exclude electrolyte from one side of the web. Preferably the web, before being electrolessly plated, is provided with holes which give additional current paths during the electroplating to ensure a more uniform deposit. The holes may be in lines longitudinally of the web, the plated web being cut along the lines to produce plated webs of lesser width. The cathodic electrode may be a rotatable drum or it may be a continuously moving conductive ribbon which passes through the plating bath in the form of a parabolic loop round a suitably shaped support. In the latter modification the ribbon, after being separated from the plated web, may be passed through a stripping bath and a rinsing bath to remove any metal plated thereon, before being returned to the electrolysis bath. In both modifications the anode in the electrolysis bath has a shape conforming to that of the cathode. In an example an electroless plating bath for depositing nickel on an elongated polyethylene terephthalate web has the composition .nickel sulphate hexahydrate.18.4 grams/litre .sodium hypophosphite monohydrate.24.4 grams/litre .acetic acid.3.6 grams/litre .sodium acetate.4.8 grams/litre .lactic acid (85%).31.0 grams/litre .sodium succinate hexahydrate.16.2 grams/litre .lead ion.5 p.p.m The bath is operated at a temperature of 180-210 DEG F. and at a pH of 5.2 /sB 0.6 (adjusted with sodium hydroxide). The web is previously sensitized with a 30 grams/litre stannous chloride solution containing 10 ml/litre of HCl, and then a 0.1 gram/litre of palladium chloride solution containing 10 ml/litre of HCl to give a thin coat of palladium, with water rinses after each immersion. Electroplating is carried out in a cobalt sulphate-nickel sulphate bath containing sodium hypophosphite and ammonium chloride and, possibly, saccharin to act as a stress removing ingredient. |
