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Cleaning copper for soldering purposes

Q. Dear Readers,

I am currently trying to clean an oxide from some small copper parts that are to be soldered to solar cells. The copper parts have been wire cut to shape and are thus coated with quite a thick oxide, not to mention contaminants from the wire cutting bath.

I have tried a dilute solution of HCl and have even mixed this with a little H2SO4 but the results are still only about 80% effective. Unfortunately the parts are quite delicate and I therefore cannot afford to vigorously tumble them although I have tried a bubbling method which is a little more effective. Once soldered, the parts are encapsulated so I cannot afford to have any residues left on them as they are exposed to extreme conditions in a solar concentrator.

Any help on cleaning copper would be greatly appreciated.


James Cotsell



A. HCl and H2SO4 are not oxidizing acids, and I think that's what may be missing. The gentlest copper bright dip is probably a mix of sulfuric acid and hydrogen peroxide. I suggest you buy this as a proprietary to get the instructions, for safety, and because stabilizers are needed to keep the hydrogen peroxide from rapidly decomposing.

Ted Mooney,
Ted Mooney, P.E.
Striving to live Aloha - Pine Beach, New Jersey

A. I assume that by wire cutting that you mean wire EDM. If the cutting parameters are off, you may be getting a "slag" rather than an oxide. If so, it is going to be much tougher than a simple oxide to get off. When you find a vendor that looks good to you, Ask them if they will do a few sample pieces for you, so you can see if it works to your needs.

James Watts
Navarre, Florida

May 26, 2015

Q. Dear Sirs

Anyone can suggest for my problem on soldering process, when my soldering operator process cannot join the tinned cable with Plated Tin Terminal, also cannot join same cable to Blackish Copper rivet ...
Please kindly suggest, either re-plating the terminals or how to clean copper rivets?

Thank you

Raeem Sterling

July 28, 2015

Hi Raeem,

You may apply electrolytic degreasing follow by acid dip to clean copper rivets. Also, you may apply post treatment step (so call solder guard chemistry) after terminal tin plating to preserve tin despoit solderability during storage/transportation.


David Shiu
David Shiu
- Singapore

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