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-----NiCl in acid copper
1998
Good day. We have an acid copper bath, in which we have a problem with Nickel Chloride drag-in. The Chloride we can test for, and precipitate with silver and filter the solution, but have a problem with the nickel.
Could anybody help me with the following:
- How to test for the nickel concentration?
- What is the max concentration acceptable before the nickel interferes with the copper plating?
- How to get the excess nickel (or all of it, preferably of course) out of the bath
Thank you for your help,
Peter
Peter Knaapelectroplating shop - United Arab Emirates
1998
I do not believe you can dummy plate out the nickel and for the same reason it should not affect your plate. I am not sure if this is true at high concentrations however.
Obviously it would be beneficial to decrease the drag in from your rinses by increasing your rinsing or maybe use ion exchange to remove the nickel and the chloride in your rinse and protect your bath.
The plating lines I am most familiar with copper plate and then nickel plate. What type of plating are you doing or is the nickel being dragged back over the copper tank?
Good Luck.
John Ring1998
1. Test for nickel using AA or ICP.
2. I am guessing that nickel may not be a problem until it reaches very high concentrations, possibly as much as 500 mg/l. I remember hearing from one bath supplier that iron wasn't a problem until it passed 1000 mg/l, and we used to occasionally permanganate treat acid copper (leaving oodles of Mn in it) without noticeable problems. The experts will have to tell you for sure.
3. Instead of trying to fix the tank, which may not need fixing, improve your rinsing and keep the stuff out of your copper tank in the first place! If you are afraid of the nickel plate passivating, put a sulfuric acid dip in front of the copper tank to keep the nickel plate active AND reduce drag-in of nickel to the copper tank.
Bill Vins
microwave & cable assemblies - Mesa (what a place-a), Arizona
1998
Peter,
I did a bit of copper sulphate ⇦ on eBay or Amazon [affil link] Heavy Electroforming over Stainless that required a woods strike prep. The above suggestion of a Sulfuric Acid, approx. 10 % by volume, pre-dip is what prevented this problem for me, along with good rinsing. But I also threw some spare Pt/Ti anodes in and Cathodized the parts for one minute. The Cathodization continuously deplated the predip of any Nickel and the Hydrogen scrubbing absolutely rinsed every nook and cranny of woods. Plus there is no chance of passivation, and if you forget about the parts, they won't dissolve!
Good Luck,
Dave,
Dave Kinghorn
Chemical Engineer
SUNNYvale, California
1998
I am not aware of any problems with metallic contamination in acid Cu solutions with the exception of Cr6+ .It would help if you could detail the actual problems that you encounter to establish what is the problem
Regards
Lynn Lewis
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