Electroless deposition of Ni-Cu-P alloys in acidic solutions

Inclusion of Cu in electroless deposited amorphous Ni-P alloys improves their thermal stability, brightness, and corrosion resistance. The mechanism of codeposition of a third element during the electroless deposition of Ni-P is still not clear. A simple model for codeposition of Cu is proposed. It claims the three different roles played by Cu added to the solution for electroless nickel plating: as a stabilizer (Cu+); as an accelerator (due to the catalytic properties of Ni-Cu alloys); and as affecting the solution stability (due to the formation of randomly dispersed copper particles in the solution). A comparison between copper content detected in the deposit and predicted on the basis of the model has been made. The model allowed production of amorphous Ni-Cu-P coatings with increased copper content and consequently improved thermal (nonferromagnetic) stability. (C) 1999 The Electrochemical Society. S1099-0062(99)01-022-6. All rights reserved.