Pitting problem with acid copper plating

Letter 1102

Pitting problem with acid copper plating

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I am having a pitting problem in an acid copper plating bath. The parts are 3 dimensional bronze plumbing parts. The parts are sanded, vapor degreased, electrocleaned, acid cleaned, 10% sulfuric, then plated at 10 to 15 ASF. The bath is 25 opg CuSO4, 4%v.v. sulfuric and 95 ppm Cl-. The bath is air agitated. The bath has been carbon treated 2 months ago when this problem came up, but it didn't help. The bath was analyzed for metals as follows:

Nickel 210 ppm
Zinc 55 ppm
Iron 350ppm
Lead 11 ppm
Cadmium 60ppm

The bath is bright blue.

If anyone has any suggestions I would appreciate them.

chris Shea

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Check for a source of fine bubbles. Is there an air leak in the suction side of your filter pump?

Bill Vins
microwave & cable assemblies
Mesa (what a place-a), Arizona

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Try to plate an non casted part and look if the problem still exist.

If there is no pits you have to change your pretreatments.

If the problem is your plating bath add an antipitting agent to your bath.

Gabriel Schonwald
Interplate Ltd.

Bnei Berak, Israel

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I have seen this a lot of times, pitting on bright acid copper can be controlled by very very good filtering.

Sara Michaeli
chemical process supplier
Israel

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Dear Chris, Try a cyanide copper strike first,the concentrated sulfuric acid from the bath will have a tendency to pit before plating. Also a little wetting agent will help.

Good luck,
David

David Guleserian
- Rhode Island

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I think I'd side with David on this one. Depending on the alloy, I would not be surprised to see that the acid copper bath is attacking it. Looking with low power magnification (loupe), is this 'pitting' perfect hemisperical craters that would be associated with gas evolution from some source, or is it roughness?

Ted Mooney, P.E.
finishing.com
Brick, New Jersey

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Dear Chris,

Try to add to your pickling bath before Cu plating some amount of brightner you use with copper plating bath. Let me know if this help you overcome your pitting problems.

Best regards
Jerzy Skowronek

Skowronek Jerzy - Water Treatment Cooperation AB ‰BY Sweden -

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SOUNDS TO ME THE CHLORIDES ARE TO HIGH. I WOULD DECANT TO REDUCE TO AROUND 60 PPM. HIGH CLORIDES WILL AFFECT THE CARRIER COMPONENT IN THE HIGH CURRENT DENSIDIES CAUSING STRIATIONS AND MAKES IT HARDER TO CONTROL BRIGHTENERS. IF ANTIPIT AGENT DOESNT WORK, I'D TRY THIS NEXT,IF ALL CLEANING POSSIBILITES HAVE BEEN PERFOMED ON THE PARTS

JOHN ROLLINS - SPEC PLATING - FRIDLEY MINN

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