Rants

Is RoHS really better for the environment?

Author: rickj • Category: Rants • Posted on Thu Jul 10, 2014 12:46 pm • Viewed: 21921x • 0 comments

A surprising number of metals are capable of spontaneously growing whiskers. They do it under ordinary room conditions. The whiskers are thin, but up to millimetres long and highly conductive. They are death to electronics. We've known about this since 1946, and found a way to eliminate metallic whiskers, but we are now inviting them back.

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At least aluminum, cadmium, gold, indium, lead, silver, tin, and zinc will grow whiskers. All of these metals have been important in electronics, though the use of cadmium is rare now that we understand its toxicity. Metallic whiskers are typically 0.5um to 10um in width, so they are difficult to see: compare this to human hair, at about 50um diameter. Their length is impressive; a specimen 23 mm long is the current record holder. With a growth rate as fast as 15um/s (that's a millimetre in 6.7 minutes) they can sneak...

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