Electronic devices may receive ESD discharges which will not fail the device immediately but at some time later (perhaps years). After a device experience an ESD hit and has not fail catastrophically still
may be degraded and hence its lifespan will be somewhat shortened. Latent damage is cumulative in nature as every time a discharge hits the device, it becomes weaker and more prone to terminal collapse, the per design component characteristics would have varied.
Unfortunately there is no way of detecting a latent fault in a device as it may pass all test and after extensive burn-in periods, unless of course we apply some destructive type of testing analysis. In
fact the device is expected to be at its worst when arriving to the purchase’s premises as an assembled piece of equipment, it would have gone through many potential latent fault exposures eg the many stages of the production line of the device, final testing, packing, PCB
assembly manufacturers, delivery subcontractors, etc…