Electronic tin whiskers may be behind Toyota recalls

An expert on electromagnetic interference was approached by the US government for an independent assessment of problems that have caused the massive recall of Toyota cars.

According to a document seen by TechEye, and written by EMI expert Keith Armstrong, the idea that the Toyota recall is due to sticking pedals is a smokescreen. In the document, Armstrong said he was contacted by the US government’s National Highway Traffic Safety agency to discuss the EMI (electro magnetic interference) implications behind cases of unintended acceleration.

He says tests performed by the motor industry, by the Japanese government and the US government show it’s almost impossible to stop a runaway behicle with the brakes. And if EMI is involved in cases like these, there’s no trace of a defect after an incident.

He said that if electronic circuits, software or firmware in cars go full throttle or otherwise cause an error, the circuits show no more stress than if it was behaving normally and are undetectable afterwards.

Armstrong said that manufacturers are denying that EMI could be a cause of sudden acceleration, but that view is logically unsound. Armstrong said that this is a “bankrupt argument” and that any competent design engineer knows this.

He also says that complex electronic systems are difficult to make reliable enough for safety.  He claims that electronics systems in automobiles don’t use the safety principles that are common in other industries, and even mandated. People are a poor safety back up where cars are concerned.

The standard for functional safety is IEC 61508[2] and the auto industry is lagging behind and has only just produced the first draft of its own version of the standard.

He said that lead free soldering is also a problem and can cause tin whiskers to gow which cause short circuits. This problem is documented here, and has caused serious problems in the computer industry previously.

Software, he concludes, can also be affected by EMI and can cause instability to electronic circuits.