Summary for acid copper plating pitting Discussion
acid copper plating pitting is discussed as a troubleshooting problem on bronze plumbing parts that were cleaned, acid dipped, and plated in an air-agitated bath. Chris Shea reports a bright blue bath with 25 opg CuSO4, 4% sulfuric acid, 95 ppm chloride, and elevated metals, and says carbon treatment did not help. Ted Mooney suggests checking for a source of fine bubbles, such as an air leak on the suction side of the filter pump. Jerzy Skowronek recommends adding some of the copper brightener to the pickling bath before plating. John Rollins believes the chlorides are too high and advises decanting to reduce them to around 60 ppm, noting high chlorides can affect the carrier and brightener control. Another contributor agrees that poor filtration, high chloride, or excess additive can all cause pitting. Diki Mulhaedi asks whether Hull Cell testing can reveal the issue, and Ted replies that a hanging Hull Cell or racked panels may be needed if standard Hull Cell panels do not show the defect.
1998
Q. 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 350 ppm
- Lead 11 ppm
- Cadmium 60 ppm
The bath is bright blue.
If anyone has any suggestions I would appreciate them.
chris Shea
A. 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
1997
A. Try to plate a non cast part and look if the problem still exists.
If there are no pits you have to change your pretreatments.
If the problem is your plating bath, add an anti-pitting agent to your bath.
Gabriel Schonwald
Bnei Berak, Israel
1998
A. I have seen this a lot of times, pitting in bright acid copper can be controlled by very very good filtering.
Sara Michaeli
Tel-Aviv-Yafo, Israel
1997
A. 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
1997
A. 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 hemispherical craters that are associated with gas evolution from some source, or is it roughness?
Ted Mooney, P.E.
Striving to live Aloha
finishing.com – Pine Beach, New Jersey
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1997
A. Dear Chris,
Try to add to your pickling bath before Cu plating some amount of brightener you use with copper plating bath. Let me know if this helps you overcome your pitting problems.
Best regards
Skowronek Jerzy
– water treatment – Sweden
1999
A. SOUNDS TO ME THE CHLORIDES ARE TOO HIGH. I WOULD DECANT TO REDUCE TO AROUND 60 PPM. HIGH CHLORIDES WILL AFFECT THE CARRIER COMPONENT IN THE HIGH CURRENT DENSITIES CAUSING STRIATIONS, AND MAKE IT HARDER TO CONTROL BRIGHTENERS. IF ANTI-PIT AGENT doesn’t WORK, I’D TRY THIS NEXT, IF ALL CLEANING POSSIBILITIES HAVE BEEN PERFORMED ON THE PARTS.
JOHN ROLLINS
PLATING – FRIDLEY Minnesota
1999
A. Dear seniors,
I have experiences regarding this pitting problem in acid copper … all everything mention in this forum are correct in my view, such as:
– insufficient good filtration will generate pitting
– too high chloride also
– even sometimes excess of additive also
So sometimes we have to try one by one from those possibilities.
Q. But the question I would raise to this forum is can we know that the pitting from hull cell plate? Because sometimes the pitting doesn’t show in the hull cell but appeared in the part. Does anyone has idea about this? Because my concern is if we can control by hull cell then it’s more easy to control it on the solution
diki mulhaedi
chemicals supplier – jakarta, indonesia
August 10, 2015
A. Thanks Diki. If the pitting is not present on Hull Cell ⇦ huh?
panels, a next step might be to try a “hanging Hull Cell”; this has holes in it and actually sits in the main plating tank so you can look for problems that don’t appear in the standard Hull Cell test, but might appear in this situation. Alternately you can rack (or “wire”) Hull Cell panels to your plating racks to see if they pit when carried through the whole cycle.
Regards,
Ted Mooney, P.E. RET
Striving to live Aloha
finishing.com – Pine Beach, New Jersey
Need quick confidential answers? $25
Need project assistance? $100/hr.