Short Circuit Stout, Wheatstone Bridge, and Ampere Amber are three of the craft beers on tap at a micro-brewery owned by three—maybe you guessed who already?–electrical engineers.

Component manufacturers are continually developing new and smaller packages for components that are mere fractions of a millimeter and have board to component clearances of less than a mil. Pick and place machines have new accessories that allow placement of these almost invisible parts. Components are placed extremely close together. How do you effectively clean under something so small?

No-lead solder is a relatively recent legislated fact of life that necessitated new solder, new fluxes, higher temperatures, and new solder processing equipment. Many new approaches, alloys, chemicals, and soldering processes have been developed to address these issues. Tin whisker problems also increased dramatically. Time-delayed effects, however, often will not show up until a product is out the door and has been in service for even a year or two. The pace of product development covers up some of these time-delayed issues when products are routinely discarded for newer models. For products such as mobile phones, problems don’t often show up because comparatively few people are using a mobile phone that is more than 2-3 years old.

Various metals widely used in electronics, such as tin and zinc, often show hairlike protrusions on their surfaces. These “whiskers” can be responsible for current leakage and short circuits in electronic equipment, causing billion-dollar losses in the auto, aviation, and space industries. But the formation mechanism of whiskers has remained a mystery for over 60 years and researchers have been unable to provide even order-of-magnitude predictions of whisker parameters.

Now, Victor Karpov at the University of Toledo, Ohio, has proposed a theory that provides, for the first time, quantitative estimates of whisker nucleation, growth rates, and length distributions.

Karpov’s analysis delivers estimates of whisker parameters that are generally consistent with observations

more reliable models of whisker evolution will be useful not only for microelectronic technologies, but also for large-area photovoltaic

Thanks to that wonderful ROHS stuff the EU passed more than a decade ago, we should be seeing a few high-profile failures of electronic components due to tin whiskers. These tiny hair-like extrusions of metal found most commonly in lead-free solder have destroyed billion dollar satellites and shut down nuclear reactors, despite no one knowing exactly how these whiskers form. Now there’s a new theory of metal whisker formation (abstract, unless you have access to APS) that actually has predictive power.

[V. G. Karpov] from the University of Toledo suggest these whiskers are formed by differences in charge induced by metallurgical anomalies – contamination, differences in the grain of the solder, and oxides.

The theory of whisker growth is generally consistent with observed rates of whisker growth and other properties.

The debate over the role of tin whiskers in Toyota’s unintended acceleration case has returned, and government administrators are expected to answer more questions on the subject this week.

Even after the National Highway Traffic Safety Administration (NHTSA) declared in 2011 that there was no electronic cause for Toyota’s problems, the debate had quietly continued. It rose to prominence again this month, when a US senator stepped in.

“Recently, whistleblowers have provided my office with information, supported by documentation, which raises concerns that the scope of the NHTSA and NASA investigations may have been too narrow,” Sen. Charles E. Grassley (R-IA) wrote in a letter

Tin whiskers — small metal dendrites that sometimes form on electroplated tin — are an important topic for design engineers, because they can cause short circuits and arcing in electrical equipment. In Toyota’s case, tin whiskers were considered a potential culprit in the “unintended acceleration” claims that grabbed headlines three years ago.

The Cassini spacecraft’s plasma spectrometer, responsible for measuring the energy levels of electrons and protons, is back up and running after NASA engineers spent nine months troubleshooting an electrical problem with it.

The spectrometer was turned off last June after reports showed fluctuating voltage.

After months of investigating the matter, it was discovered that the tin plating on the spacecraft’s electronics components had grown “whiskers.” While very small (less than the diameter of human hair), they were still big enough to contact another conducting surface. This, in turn, caused the device to short out.

Researchers aren’t exactly sure why this phenomenon occurs, but they now know that “tin whiskers” can occur both in space and here on Earth.

“We can’t do anything about the tin whiskers, but the research showed that the whiskers could not carry enough current to cause harm to the spacecraft. So we believe we can live with them.”