ACID COPPER PLATING PROBLEM
A discussion started in 2007 & continuing through 2017(2007)
Q. We are experiencing a problem with our acid copper. Our amps are dropping to zero while our volts are increasing and the plating has no shine. We tried different rectifiers and the problem remains. We are now carbon filtering the tank but it does not seem to be helping after 2 days. The tank is 200 gals. I'm at the end of my rope with too many deadlines unable to be met until the problem is rectified. Thanks...Don.Don Prestage
plating shop owner - USA
A. If the anodes are phosphorized copper as they should be, then the anodes are polarized. Take them out, remove the bags, replace with new clean bags, put back in. The black sludge is "hazardous waste".
Robert H Probert
Robert H Probert Technical Services
Garner, North Carolina
Editor's note: Mr. Probert is the author of Aluminum How-To / Aluminio El Como
A. Service anode or change to new.John Hu
The first thing you need to do is a complete analysis of your solution to check that your bath is in balance. Carbon treating without knowing what you are treating for is pointless.
If your analysis shows that the copper and acid levels are correct then do a hull cell and play with the brightener levels until you get a satisfactory plate in the mid range current densities.
If all else fails ask the chemical suppliers if they can help, they are usually extremely helpful and can normally offer the services of an expert to try to sort out your problems.
I must admit that it is a long time since I played with acid solutions, normally dealing with cyanide or pyrophosphate systems these days so I apologise for my vagueness but there are simple rules to apply to a situation like yours: Analyse, Hull Cell, expert, dump.
If your production pressures are high sometimes it is more economical to dump the solution and start again rather than have a long down time while you try to sort the problem.
Hope you get your problem sorted soon.
Aerospace - Yeovil, Somerset, UK
A. You will "lose" your ability to carry current when the amount of copper in solution has become too high raising your ratio of copper sulfate.
Titrate the solution and see if you are within spec; if not, the easiest solution is to cut the bath. You can test it out first in Hull Cells.
plating shop - Hbg, Pennsylvania
A. Hi Don
plating - Turkey
A. This is classic anode polarization and most likely due to too high copper sulphate content and possibly low temperature.
- Port Melbourne, Australia
A. Hi Don,
The chloride level in your bath is low. The level must be above 40 ppm and below 80 ppm for satisfactory passage of current.
Do this and let us know.
- New Delhi, India
With deep regret we
sadly advise that
Asif passed away
on Jan 24, 2016
A. Hi Don,
I believe your problem is TOO much chloride -- are the anodes getting a white coating on them? If so, take them out and scrub until you see clean copper.
You may have to do this a few times.
I had this same problem in my electroforming tank.
- Durban, South Africa
A. The total concentration of copper sulfate and sulfuric acid should not be higher than 300 g/l otherwise you get polarisation.
chemical process supplier
A. Everyone has valid advice. Basically they have told you to check everything since you could have too much or too little. The most valid advice is to call your supplier. They generally will offer to run an analysis of your bath at no charge (this is included in what is called customer service) and since you are having a problem they should then offer their learned opinion of what the corrective measures are.
Before everyone jumps on and comments I would like to clarify that periodic analysis by the vendor is not a substitute for having the capacity to have routine analysis done on premises or locally, nor that every time you have a small problem go running to your vendor (enough people do to give me days when I wish cell phones had not been invented). But the vendor does have product specific knowledge to their formulations as well (usually) as having people with a wealth of knowledge. Also your supplier should be sure you have a Technical Data Sheet for the products and processes being purchased, analytical instruction and a trouble shooting guide.
One point I forgot, if you are using "city water" in your acid copper, you should have the necessary chloride without adding any. If you have been making large additions of water and not of acid or salts that would tend to raise the chloride level (maybe). Get an analysis and test panels done!
- Great Neck, New York
October 2, 2011
A. I am sure that your problem is high copper sulphate if your bath solution about 100 liter only you must to get out 25 liter from your solution and put 25 liter ionized water good luckMajed Janineh
- Beith Lehem Israel
A. Dear Don,
At first I am not sure what is really the issue in your plating bath.
At first you need to analyze the bath very regularly specially if it's a 24-hr operation. Depletion of additives and other chemical varies in every panels loaded in the bath and that is why there should be a regular routine analysis.
1) firstly, how is the current density, is it calculated as per number of panels per rack.
2) how is the chloride content and how is the color of the anodes, black phosphorized film should be seen on the anodes.
3) what is your process, is it pattern or panel plating (for PCB process), should the color of the bath is greenish then it should be contaminated much with more organics on it. maybe there is a need to do carbon treatment and check TOC.
You need to investigate further and the assistance of the chemical supplier also will help a lot to troubleshoot the issue.
Thank you very much.
Reducing Sulfate level in a Copper BathDecember 3, 2017 -- this entry appended to this thread by editor in lieu of spawning a duplicative thread
Q. Hi everyone, I am a student of Chemical Engineering in Brazil and recently I started an internship in a company that works with electroplating. We have collected cylinders for use in rotogravure.
I'm very new to the subject and it's been hard to find materials (handbooks are all sold in the USA and I can not find any PDFs), so I'd like to rely on your experience to answer the following question:
How do you make the correction of copper baths?
We work with 1000 L baths with H2SO4: 50-70 g / L and CuSO4: 200-220 g / L.
Here the baths are in contact with a very high amount of copper's chips, so with the passage of days the amount of sulfate increases a lot and to correct it the head of the sector uses the following strategy: Discard a certain amount of the bath (for example 100 L), complete the bath with water again and add more acid to compensate for what was lost.
In my opinion, we lose a lot of copper, acid and water every week. I've already suggested removing copper chips from the bath, but since I'm a newbie I do not have much credibility.
Another idea I thought was to precipitate sulfate with Barium Carbonate. I do not know if it works, but I intend to experiment with it.
Thank you for your attention and sorry by my English!
- João Pessoa, Paraíba, Brazil
A. Hi cousin Jerlan. I think your problem is more properly described as excess copper rather than excess sulphate per se; there is no place for sulphate to come from during operation, but dissolving anodes can contribute to excess copper.
You will read above that two responders do suggest your action of bailing out some of the solution and replacing it with water -- but I think this was suggested as an emergency fix, not as an operational routine.
The thing to investigate is whether you are using phosphorized anodes. These are intended to solve just this problem. After that is assured, then you might consider reducing the number of anodes and, if necessary, making a small and controlled chloride adjustment.
Ted Mooney, P.E. RET
Pine Beach, New Jersey
Striving to live "Aloha"
December 28, 2017
Thanks, Mr. Mooney! It really helped me.
Sorry it took so long to answer :)
- João Pessoa, Paraíba, Brazil
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