GB1253224A - - Google Patents

Abstract

1,253,224. Nickel plating. STAUFFER CHEMICAL CO. Nov.21, 1968 [Dec.4, 1967], No.55225/68. Headings C7B and C7F. An electroless nickel solution comprises nickel ions, hypophosphite ions, and fluoborate and/or sulphamate ions, the pH of the solution being 4.0 to 7.0. The preferred sources of fluoborate and sulphamate ions are Ni fluoborate and Ni sulphamate respectively; this avoids the introduction of undesirable extraneous ions into the bath. In order that high nickel ion concentrations may be achieved in the bath, glycolate and/or acetate ions may be added thereto, preferably as the corresponding acid. The pH of the solution is preferably maintained above 5.3 using a borate buffer, and plating rate accelerators such as ammonium fluoride and/or thiourea may be added. A wetting agent may also be added, with a non-ionic type such as polyoxyethylene 2-ethylhexyl phosphate being preferred, but other suitable agents are mentioned. The ranges of concentrations for the above mentioned ingredients, not all of which need be present simultaneously, are: - Nickel ion 1 to 40 g/l Hypophosphite ion 59 to 150 g/l Fluoborate and/or sulphamate ion 2 per Ni ion Borate ion 15 to 50 g/l Glycolate ion 7 to 35 g/l Acetate ion 10 to 25 g/l Ammonium fluoride 2 to 10 g/l Thiourea 0.2 to 0.8 p.p.m. A solution as described above can be used in an electroless-electrolytic process, where, after deposition of a first layer electrolessly, electric current may be applied so that a second layer is deposited electrolytically. The following substrates are catalytic and may be directly nickel-plated: Fe, Co, Ni, Ru, Rh, Pd, Os, Ir, Pt and Ag, whilst Bi, Cd, Sn, Pb, Zn, plastics, glass, and wood must be sensitized prior to plating by known methods, e.g. SnCl 2 /PdCl 2 . Prior cleaning and degreasing may be necessary and suitable procedures are described.