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How to reduce smut on sulfurized nickel (S-nickel) anodes

Dear all , could have advise me for Pure Nickel sulfamate plating bath please? I'm using Pure-Nickel sulfamate for plating on my product. We found Ni pH drop during running so we decided to change anode from Sulfur-free anode to S-anode.

After that, pH tendency up (increase trend), finally no more pH problem. But beside of this activity I found Nickel anode generates smut (EDX analysis shows NiS). This smut has contaminated my plating solution. Then plated parts show Ni whisker on my part. Plating bath conditions show a little bit Ni metal concentration reduce even too much drag out. Could help to advise me how to reduce smut on S-Ni anode ?

APIROM WATTANAWIKKIJ
leadframes - UTHAI, AYUTHAYA, THAILAND
2003

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Hi, cousin Apirom.

Sulfurized nickel anodes are widely used, and they don't generally cause any contamination of nickel plating solutions -- but they do require anode bags to contain the smut. Are the anodes in bags? Sometimes even double bags are used. The purpose of sulfurized anodes is to more readily dissolve into the plating solution. Although there may be some relationship between the anodes and the nickel whiskers, I do not think that the sulfurized anodes are causing the whiskers.

Regards,

Ted Mooney, P.E.
Striving to live Aloha
finishing.com - Pine Beach, New Jersey
March 8, 2011