Camille Good has posted an interesting discussion of the RoHS-awareness of product safety organizations UL and CSA. I was particularly glad to read about the prohibited flame retardants in ABS, a kind of plastic used for making housings for electronic products, as I had not seen info on the extent to which PBBs and PBDEs are used in our industry. (I wish that more discussion of this topic would appear in the Halogenfree forum.) She concludes with a question. I can't contribute to that, but I would like to comment on a topic she touched on - cadmium used as an electrical contact..
In her posting, Camille referred to the disappearance of cadmium contacts from RoHS-compliant products. This is a topic that was discussed quite a few months ago in this forum, including by Nick Jolly, then of the UK's Department of Trade and Industry. The latest information from DTI appears in its guidance document, dated July 2004, on implementation of its regulations implementing the RoHS directive. It is available at <http://www.dti.gov.uk/sustainability/weee/RoHS_Regs_Draft_Guidance.pdf> http://www.dti.gov.uk/sustainability/weee/RoHS_Regs_Draft_Guidance.pdf.
At the end of that guidance document is Annex C, which provides quite valuable "Guidance on the specific applications of mercury, lead, cadmium and hexavalent chromium set out in Schedule 2 of the RoHS Regulations, which are exempt from its requirements." In that annex is a discussion of cadmium, which reads:<?xml:namespace prefix = o ns = "urn:schemas-microsoft-com:office:office" />
11. Cadmium plating except for applications banned under Directive 91/338/EEC (OJ No. L 186, 12 July 1991, p. 59) amending Directive 76/769/EEC (OJ No. L262, 27 September 1976, p. 201) relating to restrictions on the marketing and use of certain dangerous substances and preparations.
Directive 91/338/EEC amending Directive 76/769/EEC relating to restrictions on the marketing and use of certain dangerous substances and preparations, gives the following definition of cadmium plating: "Within the meaning of this Directive, 'cadmium plating' means any deposit or coating of metallic cadmium on a metallic surface." This definition is seen as applying for the purpose of the RoHS Regulations. [Note that the cadmium does not need to have been deposited by a chemical plating process to qualify for this definition.]
Subsequently, the Marketing and Use Directive (as amended) bans the use of cadmium plating in a variety of product sectors. However, that Directive allows the use of cadmium plating for "electrical contacts in any sector of use, on account of the reliability required of the apparatus on which they are installed." As a result, in this context cadmium plating is prohibited for products manufactured in the household goods and central heating and air conditioning plant sectors. However, it is viewed as being permitted for electrical contacts in all the WEEE categories to which the RoHS Regulations apply.
I take it that in the UK at least, the use of cadmium for electrical contacts is regarded as permitted by the RoHS directive. Since no other country seems to have issued a contrary interpretation, I think that a good case could be made for not abandoning cadmium contacts where it is of benefit to the application.
Gordon Davy
Baltimore, MD
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410-993-7399
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