plating, anodizing, & finishing Q&As since 1989
Why does Ni prevent Cu migration to Au?
I am new in electroplating field and I would like to know why Ni prevents the migration of Cu to Au?
Thanks a lot Regards,KT
- Hong Kong
First of two simultaneous responses -- 2003
For better understanding please compare ionic radii of Au, Cu, Ni with each other you will find out the mechanism.Hadi Khosravi
Tavaanazmayan - Tehran, Iran
Second of two simultaneous responses -- 2003
Cu migrates into Au by forming a solid-solid solution. Ni doesn't form a solid solution with Cu or Au, so it acts as a barrier.
James Totter, CEF
- Tallahassee, Florida
The nickel is a "barrier layer" that stops the diffusion of copper into the gold. It is all to do with the "solubility" of one metal in another.
R&D practical scientist
Chesham, Bucks, UK