I bet like me you thought nothing grows inside your PC, how wrong we are in The Guardian Kurt Jacobsen reports on microscopic growths in your our PCs known as tin whiskers are causing circuit boards to short out and fail.

On April 17 2005, the Millstone nuclear generating plant in Connecticut shut down when a circuit board monitoring a steam pressure line short-circuited. In 2006, a huge batch of Swatch watches, made by the eponymous Swiss company, were recalled at an estimated cost of $1bn (£500m). In both cases, “tin whiskers” – microscopic growths of the metal from soldering points on a circuit board – were blamed for causing the problems.

It’s not the first time these mysterious growths have been blamed for electronics failures. In 1998 the Galaxy IV communications satellite sputtered out after just five years; engineers diagnosed its failure as due to “whiskers”.

The US military blamed them for malfunctioning F-15 radar systems and misguided Phoenix and Patriot missiles. In 1986, the US Food and Drug Administration recalled a number of pacemakers because of these same whiskers. In fact, they’ve been known about since the 1940s, and happen with cadmium and zinc, too: during the Second World War, similar whiskers would short the cadmium tuning capacitors in aircraft radios. A decade later, tin-based relays in AT&T telephone switching centres were found to cause shorts.

The solution to “whiskering”? Mix lead into the solder, as was done from the 1950s. Colin Hughes, a physicist who worked on the first British nuclear bomb, told me that the whiskering problem never came up during his career.

But now the lead is gone, by legal mandate, and whiskers are back – causing potential problems for us all.

Since 2006, lead has been banned from solder in the European Union under the 2003 Reduction of Hazardous Substance (RoHS) directive, which gave manufacturers three years to phase out lead.
The logic seemed reasonable. Removing lead from petrol (where it was used to prevent engine mistiming) brought clear environmental and health benefits, taking a harmful chemical that can affect intelligence out of the atmosphere. Removing lead from solder, the 37% lead, 63% tin alloy used to join metal objects in everything from plumbing to circuit boards, was an obvious next step to prevent it leaching into ground water from dumped items in landfills.

But without lead to tame it, tin behaves oddly on circuit boards. Left alone, tin plating, like cadmium and zinc, spontaneously generates microscopic shreds of metal – about one to five microns in diameter, or less than one-tenth as wide as a human hair – which push up from the base. If they grow far enough to touch another current-carrying location, they’ll cause a short that can wreck the equipment while leaving barely any trace.

The only response we can have I guess is get the longest warranty possible on anything we purchase.