Inductive Spike Causes Premature Transistor Failure
The worst sort of failure mode is the one that is invisible — no tests, root cause analysis, or part swap-out can ferret out the root cause.
In the EDN Tales From the Cube installment Time Bomb: The Case of the Invisible Failure Mode, Engineer Walter Lindenbach shares his ghost-hunting experience when he was called in to investigate a peculiar problem with his company’s oil-rig-monitorinig device. Time and time again, the transistor that switched the relay coil would fail within a year of installation and the units would be returned for repair.
Though it took some effort, Lindenbach describes his success at finding the failure mode and correcting the problem.