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What dissolves copper and not nickel

I have a thin nickel foil (area thickness 90 microgram/cm squared). It has a supportive backing of copper (roughly the same amount of material).

I now need to remove the copper while not affecting the nickel. What should I use? ferric chloride ⇦this on eBay or Amazon [affil links] ?

Alex Murphy
- Columbus, OH, US
2001

Alex,

A solution of ammonium hydroxide at any concentration above 30% will readily dissolve copper without affecting nickel. Only problem is its obnoxious and strong odor and of course its subsequent disposal, as it forms complexes that are difficult to precipitate. Get additional help from a waste treatment company in your area, specially if it is a large project.

Regards,

Guillermo Marrufo
Monterrey, NL, Mexico
2001