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Citric acid for copper passivation?


My company is using a dilute citric acid bath to passivate copper after etching. We then assemble these passivated components into a can, then extrude the product into a rod. My question is this: What is the citric acid doing to the surface of the copper to slow oxidation? Will this hamper bonding between the components in the subsequent extrusion?

Robert Hentges
- Carteret New Jersey


Robert, Citric acid is a chelating agent which is often used in plating industry. Recently it is used in the formulation passivating stainless steel because citric acid is helpful to remove iron existing in the oxide film on stainless steels. I believe citric acid is helpful to clean the copper surface rather than passivate copper. Actually citric acid tends to remove the oxide film on copper surface instead of forming oxide film. Ling

Ling Hao
- Grand Rapids, Michigan


Can you send documentation concerning passivation of pipe (chrome).

- hassi-nessaoud


How long does it take to form a substantial oxide layer on copper? How can this be inhibited without adding a coating?

Thank you!

Dave Bucka
- Industry, California, USA


I have been working with copper and citric acid extensively. The pH value at which you are conducting your process may very much influence the results you are obtaining.

Venkata Gorantla
- New York

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