Electronic components with time-dependent failure rates-reasons, values and consequences

For reliability calculation of electronic components, handbooks are typically used. The calculation shows a high level of uncertainty and usually has no direct relationship to a physical damage mechanism. Moreover, the calculation procedure assumes constant failure rates. A power module ( integrated in electric and hybrid vehicles) and an electrolytic capacitor were used to examine whether this assumption is universally valid. The physics of failure of both exemplary electronic components showed that the dominant failure mode had a significantly increasing failure rate. This demonstrates that the general assumption of constant failure rate for electronic components is not permissible. It has wide-ranging consequences for reliability and safety analysis of these components and their specification. The influences of an increasing failure rate on the proper specification of a component are shown. Furthermore, the influences on preventive maintenance, functional safety and availability are considered.