Metal finishing Q&As since 1989

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Zinc Whisker formation on Trivalent Chrome

My company is moving towards compliance to RoHS directive and are encountering a number of questions relating to Whiskers. While we move from Hexavalent Chromium to Trivalent Chrome are the same types of problems with Zinc/Chromium Whiskers in Trivalent processes as there is with the Hexavalent Chromium?

George Cutler
transistor devices - Hackettstown, NJ
2005

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With what I've seen on whisker formation, it's due to stress in the deposit which would be entirely related to the zinc deposit and has nothing to do with the chromate, either hex or tri! My belief is that it has no bearing on the propensity to whisker.

Now if you asked "how does removing lead from tin-lead impact whisker growth potential?" that's a whole nother matter! You'd better have a good razor if you "get the lead out"; whiskers will be a plenty!

Milt Stevenson, Jr.
Syracuse, New York
2005

When you talk about hexavalent chromium and trivalent chrome are you referring to passivate solutions or chrome plating solutions? If you are referring to passivate solutions then the same zinc plating problems will exist whichever passivate solution you use.

Dougie Lightfoot
- Fife, Scotland
2005

does the application of chromate conversion coatings give additional protection against zinc whiskers.

George Cutler
transistor devices - Hackettstown NJ
2005

The chromate conversion takes place independently of and after the electroplating process so can offer no protection against the formation of zinc whiskers.

Dougie Lightfoot
- Scotland
2005