Nickel-phosphorus electroplating and bath therefor

摘要

An all chloride bath is provided for electroplating nickel phosphorus on a substrate. The bath includes 0.7-1.3 molar Ni+, 1-2 molar Cl-, and 1-3 molar HPO3+2. The bath also optionally contains 0.2-0.6 molar PO4-3. The bath contains as little sulfate as possible. Any sodium lauryl sulfate in the bath can be removed using a carbon filter. The electroplatings produced according to the invention have Knight shift, density, and non-uniform thickness properties more characteristic of electroplated nickel phosphorus than electroless. They have lower tensile strength, increased inherent brightness, and reduced graininess compared to electroplating from baths including sulfate. The bath has increased cathode efficiency, increased conductivity, and reduced formation of unwanted precipitates compared to baths with sulfates. The bath constituents may be provided from NiCl2.6H2O and H3PO3; or from Ni(H2PO3)2 and HCl.