Metal Finishing Guide Book

2011-2012 Surface Finishing Guidebook

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Page 157 of 707

electroplating solutions TROUBLESHOOTING ROHS-COMPLIANT ELECTROLESS NICKEL BY DUNCAN BECKETT, JOHN SZCZYPKA, BOULES MORCOS, AND GREG TERRELL, MACDERMID, INC Lead and cadmium in consumer products have come under increased regula- tory scrutiny due to the growing number of products requiring end-of-life treatment and disposal. Moreover, global concerns regarding human health and environmental risks associated with the use of hazardous substances has led the European Union to enact regulations to restrict the use of certain hazardous substances. The Restriction of Hazardous Substances Directive (RoHS) was adopted in February 2003 and enacted on July 1, 2006. It restricts the use of six substances to specific limits: • Cadmium and hexavalent chromium must be below 0.01% by weight. • Lead, PBB (polybrominated biphenyls), and PBDE (polybrominated diphenyl ethers) must be no more than 0.1% by weight. • Mercury must be less 0.01% by weight and must not have been intentionally added. Of the six substances, only lead and cadmium have been used in electroless nickel (EN) plating. Since the discovery of the electroless plating method in 1944 until the RoHS Directive came into force, lead and cad- mium were relied upon to respectively provide stability for the plating solution and brightness for the resulting deposit. Prior to the enact- ment of the RoHS Directive, the type and amount of stabi- lizers and brighteners were unpublished, closely guarded trade secrets. MacDermid and other supply houses of proprietary plating chemistries did a con- siderable amount of 156 Figure 1: Roughness due to foreign matter in the solution.

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