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Copper Removal

I am trying to locate a chemical solution that will strip Copper from 1) Nickel, 2) Gold and Nickel. The overall component thickness is less than .002"

Wade Leveille
- Milford, Massachusetts

This is a very delicate operation and you will need to monitor it carefully. There is one solution you may like to try; it is a dip process using 200 g/l CrO3 with 12 ml/l conc H2SO4. This operates at room temperature and is used to remove copper from tool steels, so it doesn't affect steels and if watched carefully it probably won't affect nickel or nickel-gold.

Trevor Crichton
R&D practical scientist The Pheasantries - Chesham, U.K.

Dear Mr. Leveille,

Here is another recipe:

230 g/l sodium sulfide
16 g/l sulfur
Boil to dissolve sulfur. Use at room temperature.
Brush off loose sulfide. Rinse and dip in 10% sodium cyanide solution. Repeat several times.

Kind regards,

Sjamp van Esch
- Eindhoven, The Netherlands

Chromic acid is OK but toxic. An ammoniacal stripper is commercially available that is a better choice.

Russell Richter
Gar Electroforming Div.

Danbury, Connecticut, USA

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