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Prevention of oxidation of lead plating on copper parts
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Gentlemen;
As stated, copper fabrications only...we do tin, tin/lead (90/10) and 100% lead (97/3, 90/10 also). Recently, we have had a customer return parts to us for "oxidation". They state that under a microscope, you can see the green tint that indicates "oxidation" (if that is the correct word for it). Also, the customer tells us that the "oxidation" can be minimized by certain chemicals in the pretreatment cleaning process, but they do not know what they are.(they had another supplier with the same problem, and this supplier found the solution) Can you tell me what pretreatment methods or chemicals would prevent or deter "oxidation" on lead plating on copper parts?
The oxidation appears to be the copper (green tint) appearing thru the lead plating. Standard plating thickness is .002"
Thank you,
David Fordcopper fabrication w/plating line - Decatur, Tennessee, USA
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I haven't any experience plating lead onto copper, but have plated copper onto lead. The explanation given you sounds "hokie" as oxidation is usually prevented by post-plating processes. I suspect that the color is from oxidation of copper plated onto the parts. If so, you can probably remove the copper from the plating solution by "dummy" plating, as copper is more noble than lead or tin.
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Ken Vlach - Goleta, California |
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It seems since I first wrote this letter, I have learned that the oxidation seems to be occurring on top of the lead plating (copper battery inserts plated with 93/7% lead/tin). What is the best post-plating process (rinse technique, chemical dips, etc) to prevent the oxidation from occurring?
David Fordcopper fabrication w/plating line - Decatur, Tennessee, USA
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A dip in a solution of stearic acid in xylene is a common way to retard (but not prevent) oxidation of tin. Use matte tin rather than bright tin for better solderability. Sorry, I do not remember the mixture ratios, but it is in print in a few common references.
James Watts- Navarre, Florida
February 9, 2010
We see oxidation of copper wire through a clear jacket. How do I prevent this "greening" of fine tinsel wire?
Steve mc- Vancouver Washington USA
July 8, 2010
My question is similar: What causes oxidation and/or corrosion of electrodeposited tin plating on phosphor bronze and how to prevent it?
We observed the oxidation/corrosion on pins making up a connector and the oxidized pins are usually the first 2 pins or last 2 pins.
Thank you.
- Singapore