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Cyanide copper plating without adding carbonates

can we perform effective cyanide copper plating process without addition of carbonate to the bath solution?
If not, why should we add carbonate?
what will be the effect if there is no carbonates in the solution?

Ramanna Jakkanagoudar
newly joined plating shop employee - Bangalore, Karnataka, India
August 25, 2010

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Dear Ramanna Jakkanagoudar,

You can easily start without carbonate, however it will form over time anyway.
The hydroxide from the electrolyte reacts with the CO2 and the cyanide reacts with the oxygen from the air and so carbonates are formed in increasing amounts. After a period of time (Ranging from months to a year), depending upon the aeration of your solution, it will even cause porosity in your Copper deposit.

The initial addition is done, as carbonate increases the applicable anodic current density and some people claim it works as a grain refiner in plain non-brightener containing electrolytes. Without any carbonates in the electrolyte the anodes will passivate at much lower current density.

For further reading, buy or lend the books F.A. Lowenheim - Electroplating, Fundamentals of Surface Finishing [adv: this book on eBay , Amazon, AbeBooks] or L.J. Durney Electroplating Engineering Handbook [on AbeBooks or eBay or Amazon] , it will save you from "re-inventing the wheel"

Kind regards,

Harry

Harry van der Zanden
- Budapest, Hungary
August 26, 2010