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Tuesday, November 24, 2015

Evil whiskers

Dilbert became my favorite comic strip twenty years ago, displacing The Wizard of Id. (Special acclaim is due Catbert, the "evil HR director".) In recent months Scott Adams has featured the Company Robot, who in today's strip alludes to its powerful future through "upgrades".

Not so fast. The robot's undoing could be whiskers, one of the very strange phenomena of science.

When a device such as a smartphone or a laptop is assembled from electronic components, many connections must be made. This was true back in the days of vacuum tubes, but now the connections are tiny because today's components are smaller and packed together more densely. Then and now, connections between electronic components are most often made by solder, a soft and conductive alloy with a low melting point. There are many formulas for solder, but electronics mainly used a solder composed of tin and lead.

Until 2003, that is, when the Europeans promulgated their RoHS rules that, for all practical purposes, banned lead from solder because of its high chemical reactivity and its high toxicity when lead ions displace calcium ions in animals including humans. Calcium is very important to life! So, it makes sense to ban lead in electronic devices, but there was a reason why the lead was in solder to begin with — and the reason was to prevent whiskers that "grow" spontaneously from tin. Whiskers cause short-circuits, and they can also act as microwave antennas in places where microwaves cause mischief.

The outcome is that electronic devices are not as reliable as they once were. They simply die of old age when a whisker grows long enough or is jarred loose inside the device. (Ever had a device quit working because you dropped it only a foot or two onto a soft surface? Now you know why.) Engineers, chemists, and physicists have been struggling for 15 years now to overcome whiskers without destroying the economics of assembling electronic devices. It's difficult. Even silver and gold have been found to form whiskers.

To make things worse: when a device quits working because of whiskers, it is virtually impossible for a repair technician to find the offending "nefarious needle of pain". And if one such needle can be found and removed, odds are that its brothers and sisters will make themselves known soon.

The savvy engineer thinks, if a device might quit working in 5 to 10 years because of a whisker, why design the rest of the device last any longer? We have entered an age of disposable electronics.