Methodology of accelerated aging

Outlines are given for eight alternative black-box (i.e., input-output) methodologies that are appropriate for estimating, from external characteristics, the reliability of semiconductor lasers or other gradually degrading manufactured products with lifetimes too long to measure directly over practical time spans. These reliability estimates, which are essential for various components of such systems as submarine communication cables or satellites, are obtained from two classes of data. One class consists of the measured properties of statistically equivalent components, i.e., samples from the manufactured population, that have been operated to failure or at least to a significant degree of degradation. This degradation is often brought about in a shortened time span through the application of a temperature or other “accelerating stress” that is large compared to the operating temperature or other stress of the intended application. The other class of data is, for each component, comprised of the predeployment properties of that very component, including particularly its own predeployment degradation rate (which may also be measured under accelerating stresses). Brief consideration is given in passing to important special cases when only one of these two classes of data is available.