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Satin Coat alternative for electronic equipment enclosure

January 5, 2015

Q. I am working on a cold rolled steel, powder coated part that is used as an enclosure for a piece of electronic equipment.

The part used to be satin coat steel. Some spots on the part are masked prior to powder coating to provide a conductive electrical ground path.

Since the part is used in electronic equipment, the finishing needs to be RoHS compliant to be sold in the EU. We are no longer able to get RoHS compliant satin coat steel, and are looking at alternative finishes. Furthermore, we cannot use zinc electroplating as we've experienced significant issues with zinc whiskering in the past.

We've tried iron phosphate, but our current supplier is giving us a large percentage of parts with rust present on the masked areas. It is not clear whether this is due to inherent lack of corrosion protection of iron phosphate or has something to do with the finisher's process.

We're currently looking at using zinc nickel plating or zinc phosphate base coat instead, but both seem to not be available in Western Canada, so it might be more cost-effective to find an alternate solution.

In summary, I need a finishing process for cold rolled steel that:
- provides at least light corrosion protection
- acts well as a base coat for powder coating
- is conductive
- is RoHS compliant
- is not zinc electroplating

Any input would be greatly appreciated!

Denys [last name deleted for privacy by Editor]
- British Columbia, Canada

A. Why not nickel plating, maybe with a trivalent chromium top layer?

Jim Treglio - scwineryreview.com
PVD Consultant & Wine Lover - San Diego,
California
January 6, 2015