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Why does Ni prevent Cu migration to Au?

2003

Dear Sir,

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

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First of two simultaneous responses --

Dear sir,

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
2003

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Second of two simultaneous responses --

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
2003

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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.

Trevor Crichton
R&D practical scientist
Chesham, Bucks, UK
2003