Most semiconductor devices have lifetimes that extend over many years at normal use. However, we cannot wait years to study a device; we have to increase the applied stress. Applied stresses enhance or accelerate potential fail mechanisms, help identify the root cause, and help TI take actions to prevent the failure mode.

In semiconductor devices, some common accelerants are temperature, humidity, voltage, and current. In most cases, the accelerated testing does not change the physics of the failure, but it does shift the time for observation. The shift between accelerated and use condition is known as ‘derating.’