paul dove via EV wrote:
4.2.2.11 Tin
Tin and tin plating shall not be used in any applications unless the tin is
alloyed with at least
five percent lead to prevent tin whisker growth. The presence of at least five
percent lead shall
be verified by lot sampling.
The problem arises from variations and errors in the plating process, producing
parts that have pure tin plating, despite certification that said they were not
pure tin. Even if insulated and conformal coated sometimes whiskers would
puncture to coating or insulation.
Ah, but lead has basically been banned from new products. Everything now
has to be RoHS compliant, which means no lead.
<https://en.wikipedia.org/wiki/RoHS>.
Pure tin is not that big a deal for things like terminals and
connectors, but is a problem for printed circuit boards and soldering.
The lead ban has forced an entirely new suite of alloys, fluxes, and
soldering protocols.
RoHS is "the law" in the EU. In the US, it's not federal law, but
several states have adopted Europe's RoHS requirements (California, New
York, New Jersey, Illinois, etc.) So in effect, even products sold in
the US need to meet the RoHS standards, unless you don't sell in those
states.
--
A nation of sheep will beget a government of wolves.
-- Edward R Murrow
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Lee Hart, 2521 19th St N, St. Cloud MN 56303, www.sunrise-ev.com
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