Stopping the Tin Whisker Stalkers

Researchers aim to suppress filaments that sprout from tin coatings in lead-free electronic equipment

Just as a tiny blood clot can fell a seemingly hale human, a tin 'whisker' can bring an electronic device to its knees.

Electrical shorts caused by growth of these needle-like metal crystals have knocked out guided missiles and communication satellites, shut down a nuclear power plant, and caused heart pacemakers to fail.

Tin whiskers, which are electrically conductive, are most likely to cause a short in devices in which the electronic circuits are less than 1 mm apart, according to Galyon, who oversees IBM's tin whisker abatement efforts.

The risk is even greater in an environment such as a space capsule, under the hood of an automobile, or an airplane that is exposed to severe thermal cycling and high humidity, he says. Whiskers can also grow in consumer products such as cell phones and watches, though the ramifications are far less significant.

Whiskers have been studied for more than 60 years, but environmental regulations instituted in the European Union a year ago, and under development in China, are lending added urgency to the work. That's because these regulations severely restrict the use of lead, which electronics manufacturers have relied on for decades to reduce the growth of tin whiskers.

For the Full Chemical and Engineering (C&EN) article by Sophie L. Rovner see
http://pubs.acs.org/cen/science/85/8529sci1.html