Try ammonium per sulphate (20% approximately).  It works beautifully.
We use that regularly


cheers

Muralidhar



>>> yoonsw@ime.a-star.edu.sg 05/21/03 11:02AM >>>
I'm looking for the selective Ni etchant which does not attack Cu.
I tried with HNO3. It works with more than 100um dimension.
But now I have to work with 50um dimension. So undercutting is too
severe.
After etching only 30um left. There was about 10um undercutting.
Actually Ni is NiV.

Thanks in advance.