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How to maintain pyro-copper?

I run a pyro-copper plate line, using the copper plate as a mask for heat treatment. The normal chemical analyses is carried out, with twice weekly checks of pH, ammonia ⇦this on eBay or Amazon [affil links] , copper and pyro to copper ratio. I have just introduced Hull cell into the checks and this has enabled me to get better control. The only grey area I have is cyanide contamination (due to the strike), should I only react from the results of the Hull cell. Or treat with hydrogen peroxide on a weekly basis. If so what is the procedure.

Peter O'Shea
Plating Shop - Somerset, UK
2007

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Peter,
If you are dragging in Cn to the pyro Cu bath you will have to adjust the ph downward often. If it does become a problem, rinsing after the strike should be increased. If that doesn't work a mild potassium hydroxide dip before the pyrophosphate Cu will help. Good Luck!

Mark Baker
Process Engineer - Syracuse, New York
2007

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Hello!

as a follow-up to this topic, I was wondering if anyone knows of a good ammonia monitoring protocol for the pyrophosphate copper plating process. The literature has been a great help for analytical chem techniques to monitor e.g. pyro/Cu ratio, but I have found that maintaining the correct ammonia concentration has still come down to empirical means: "From experience I've learned I need to add X mL/L per day" etc.

I would like to quantify the concentration of the active NH3-containing species in my electrolyte somehow in order to keep it as constant as possible. Any ideas?

Thanks in advance!

Iain Brooks
- Toronto, Ontario, Canada
February 19, 2008