

USC doctoral student unravels ‘tin whisker’ mystery - brianl
http://www.sc.edu/news/newsarticle.php?nid=5371#.UMQOcOTAdnE

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Dylan16807
Congratulations, now can you actually link to the paper instead of summarizing
it in half a sentence as is "caused by high-strain gradient built up inside
the device"? This is useless reporting.

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djcapelis
It is a bit hard to find one that isn't behind a paywall, but here's the
actual paper:
[http://www.osti.gov/bridge/servlets/purl/1013351-BXJitV/1013...](http://www.osti.gov/bridge/servlets/purl/1013351-BXJitV/1013351.pdf)

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cantrevealname
I assume whiskers cause a short circuit. Why can't the circuit board be coated
with plastic, epoxy, non-conductive paint, or something to prevent the
whiskers from causing a short?

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kqr2
Conformal coating is often used for protection in harsh environments.

<http://en.m.wikipedia.org/wiki/Conformal_coating>

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__alexs
Tin whiskers can break through conformal coating in some situations and the
coating process does not always cover the entire surface evenly leaving thin
areas or even entirely uncovered places in which whiskers can still form and
escape. [http://www.freelists.org/post/tinwhiskers/NASA-
experiments-c...](http://www.freelists.org/post/tinwhiskers/NASA-experiments-
conformal-coat-vs-tin-whiskers)

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guan
This is the University of South Carolina, not Southern California which most
people probably associate with “USC”.

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bcl
"Historically lead (Pb) has been added to the solders to prevent whisker
growth. Due to the harmful effects on human health and environments, it is no
longer a valid solution to prevent whisker growth with lead. With the shift to
whisker- prone “Pb-free” solders, controlling whisker growth from low melting
point metals has again become technically challenging."

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monochromatic
> While manufactures had been able to control some whiskers by mixing small
> amounts of lead into tin solder, the 2006 European Union ban on lead in most
> electronic equipment had ignited a debate among scientists about whether
> whiskers would remain a perpetual problem.

Oh Europe. Yes, let's ban the use of minuscule amounts of lead so that people
will have to replace entire devices when they fail.

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schwarz
that's not necessarily true.

As a mechanical engineer I used to work in an electronics factory. there is
still a lot of soldering done by hand. not to mention that the operators of
the automated soldering machines. during this soldering process there is a
considerable amount of fumes, even though you're using blowers and filters,
that the workers are exposed to. Lead is known to be hazardous for long
exposes. So I guess keeping the manufacture-workers safety is as important as
the end user's one.

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shorttime
This is an amazing discovery. I'm surprised it isn't more prevalent in the
news. This whisker issue has been a thorn in the side of many since ROHS was
implemented. The biggest impact with this I see is safer, more reliable
planes. How exciting.

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dav
If the functionality loss is caused by these whiskers shorting circuits, why
can't one simply restore functionality by lightly scraping the soldering to
knock off the whiskers?

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Osmium
The whiskers are often far too short for that to work, and that assumes the
whiskers are even exposed such that you could "scrape" them. Furthermore,
there'd be a risk you'd end up depositing the whiskers elsewhere on the
circuit...

