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-----Coverage problem with bright nickel bath
Q. I am using a bright nickel sulphate bath. All brighteners, leveling agents and wetting agents seem to be fine but I am only getting a very thin plate in the low current density areas. I'm running a PH of 3.8 to 4.2. I would appreciate any information and/or insight into this problem.
Thanks,
William A Steeverowner/operator metal finishing shop - Fredericton, New Brunswick, Canada
2004
A. I would suggest running a standardized Hull Cell ⇦ huh? panel to make sure the problem is actually in the nickel bath, and to further quantify what is meant by very thin plate in the LCD areas, William.
Ted Mooney, P.E.
Striving to live Aloha
finishing.com - Pine Beach, New Jersey
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2003
First of two simultaneous responses --
A. How thin is thin and how low is "low current density areas"? Do you know how thick the nickel should be in these LCD areas? Please give more details.
Trevor Crichton
R&D practical scientist
Chesham, Bucks, UK
2004
Second of two simultaneous responses -- 2004
A. WILLIAM,
I READ YOUR PLATING PROBLEM, I THINK WE DO NOT HAVE ENOUGH INFORMATION FOR YOUR NICKEL BATH. MR.TED SAID RUN THE HULL CELL PANEL HE IS RIGHT TO RUN THE PANEL..WE DO NOT KNOW THE CONCENTRATION OF YOUR BATH, LIKE NICKEL sulphate, NICKEL CHLORIDE AND BORIC ACID, BAGS YOU USE FOR NICKEL ANODE BASKETS ⇦ huh? HOW OLD IS? YOUR PART HAVE DEEP RECESS AREA ?
Popatbhai B. Patel
electroplating consultant - Roseville, Michigan
A. I agree with the previous replies that there is not enough info in your letter. Yet I would operate the solution with a higher PH. 3.8 is very low for a bright nickel (it is OK for sulfamate, not for sulphate). Try to raise the PH to 4.3-4.6.
Sara Michaeli
Tel-Aviv-Yafo, Israel
2004
A. There is no argument that more information is needed. However, there are certain checks that can be made prior to a detailed chemical and Hull Cell evaluation. I suggest checking the anode baskets (if baskets are used.) There may be a buildup of black sludge that will not only insulate the effective anode area, but cause the destruction of the brighteners in the bath. Usually this is seen when the baskets are less than 1/2 full. Also, you can check each and every bus bar joint from the source of the DC current to the plating tank. Any hot joints could indicate corrosion is present and is reducing the amount of current reaching the tank. A check of the Current Source by a good technician could do wonders.
By this time the Lab folks will have the analysis and Hull Cell done, and interpreted. Remember to keep your eyes open. Problems can often be right in front of us, and we walk right by them. Good luck.
Ed Budman [dec]
- Pennsylvania
With deep sadness we advise that our good friend Ed passed away Nov. 24, 2018
2004
Q. Good day to all,
We seemed to have encountered a problem with our Technics "bright" Ni bath. It's a manual operation and we are running at around 50 amps per sq. ft. for 7 min. with a pump running and plenty of air agitation. We currently are plating machined brass caps and our parts are getting plenty clean in the beginning between soak and electroclean, and when we rack the parts we find it will be a beautiful .0002- .0004 plating on the outside and 1/2 way up the inside then it stops. We think part of it may be these new 18-spot racks. So on the next run we ran a solo part held by a copper wire with the air and pump turned off and the amps all the way down to 5 amps per sq. ft. for 7 min and the part..... Perfect! Inside and out. We are thinking the racks / wetting agent. But why would it plate so well with no agitation in a low current density area? Totally stumped.
Owner/ operator/ student - Carson City, Nevada, United States of America
July 13, 2013
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July 16, 2013 A. Hi Glen,  Blake Kneedler Feather Hollow Eng. - Stockton, California A. Hello Glenn, process engineer - Malone, New York July 17, 2013 |
A. Dear Glen,
There could be numerous reasons for poor throw in LC areas. From low nickel chloride to surface tension on parts caused by your wetting agent. Make sure you are getting the amps your rectifier is reading to the cathode. Low bath movement vs a bubbling brew is best. But also you should be turning the tank over 3 to 5 times an hour in order to form a diffusion layer.
Bob Winslow
- Dayton, Nevada, USA
July 22, 2013
July 24, 2013
A. Good day Glenn.
Hope you sorted out your problem. There was good advice given and I would like to offer some more.
18 pcs. on new racks do not plate well up in the interior (LCD) of the parts @ 50 ASF, but one piece on copper wire @ 5 ASF plates outstanding with no air/agitation. That is a huge reduction as ASF.
It doesn't indicate a brightener/carrier overload/imbalance, as this will show up in the LCD areas.
What is the spline material UNDER the plastisol coating of your new racks? I have had similar issues plating with new racks VS old racks, and the new ones were splined with SS with CU hooks VS the old racks splined with Cu. The SS does impede current flow. Is there air entrapment in the interior areas of the CAPS, explaining no air/agitation provides better results? What is the position of the cap?
Why not run a hull cell to determine throw as LCD on a panel, and find the actual ASF throw. I would also verify the amperage on the rectifier.
Hope this helps and happy electrolyzing!
Regards,
- Whitby, Ont., Canada
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