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Poor adhesion of Nickel plated onto Nickel

1999

Hello, I'm an Italian student in electronic engineering and I need some information on Nickel electroplating for my thesis. In my thesis I must plate nickel from a nickel sulfamate bath onto a seed of nickel, obtained by thermal evaporation, through some photoresist mold (like the liga process). After plating I obtain nickel structure of some micron in thickness but these structure have a very poor adhesion to the nickel seed layer. I have tried to polish the nickel seed layer (before plating) with a dipping in a solution of HCl and water (10%) but the results are the same.

I will be very grateful to you for an hints to resolve my problem.

with best regards

Andrea Morini
- Pisa (Italy)

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1999

Hi, Andrea. You need a Wood's Nickel Strike (or perhaps a sulphamate nickel strike). Nickel passivates quickly, that is, it grows a thin layer of tarnish. You can't plate onto tarnish; rather you need this high-acid nickel strike to simultaneously attack the tarnish and deposit fresh nickel.

Dini's "Electrodeposition" has a great chapter on nickel strikes and adhesion. Good luck.

Ted Mooney, P.E.
Striving to live Aloha
finishing.com - Pine Beach, New Jersey