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Durable, Conductive, RoHS Aluminum Coating Suggestions
-----) May 16, 2022
Q. I am designing an aluminum tool (6061-T6) that needs to have a durable finish, is conductive (or at least ESD safe), and is RoHS compliant. I have ruled out chemical conversion coatings due to their lack of durability, ruled out anodization due to its lack of conductivity, and I am now considering an electroless nickel, though I hear they are not all RoHS.
I am trying to find a process that is inherently RoHS without specification on a drawing, as it would require additional documentation to validate RoHS compliance based on our procedure.
Any suggestions on finishes? Or is there another type of note I can specify without calling for RoHS specifically? (Like a type of plating or rinsing solution.)
- Milwaukee, Wisconsin
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A. Hi Sean. It is true that some electroless nickel processes contained lead, cadmium, or other RoHS proscribed substances in the past. I'm not sure that any major supplier still uses them, but there is nothing preventing a small, foreign, or home-brewer from including them. But I don't think this situation applies only to electroless nickel. Conversion coatings often had small amounts of non-RoHS materials in them as well. And zinc platers have been known to accidentally place a few cadmium balls in their zinc plating tank.
I appreciate your predicament and hope someone can correct me but I think it is difficult to insure RoHS compliance without specifying it. Some day the standard specifications for various platings may be updated to include a requirement that the coatings be RoHS-compliant, but to my knowledge it's not the case so far. Good luck!
Luck & Regards,
Ted Mooney, P.E. RET
Striving to live Aloha
finishing.com - Pine Beach, New Jersey