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Letter 030
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Larry Hanke |
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----- It is likely that a nitric acid solution of a moderate strength 20-40% will dissolve Cu-Zn without touching the noble metals. You'll have to experiment a bit with the concentration and immersion time, but it should be doable.
----- If all you want to do is remove Copper and Zinc from Platinum and Iridium any number of etches for Copper should be able to do the job. And remove the Zinc almost incidentally. A Persulfate/Sulfuric Acid Microetch for small amounts of work, or a Ammoniacal etch for large amount should do the job with no attack on the substrate. Contact a vendor of Printed Circuit Board processing chemicals for the Persulfate, or use generic Sodium Persulfate at 8 oz/gal in 2 percent Sulfuric, at 80-100 F.
Rudy Sedlak |
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