Long-life electronic products need to be put in stress environment for long durations in order that items with infant mortality or defects are weeded out from the products.However

long stress durations cause aging effects on good items.For some products

failures are defined in terms of performance characteristics degrading some critical values.For reducing durations and aging effects

this paper analyzes the difference between normally and abnormally degraded products

assumes the distribution of product degradation characteristic variable is contaminated distribution model

and presents a degradation screening test design.This design firstly ascertains the model coefficient using identifiable condition of contaminated distribution combined with the analysis of degradation test

and then ascertains screening duration and screening critical value.Lastly

this paper gives an example to illustrate the feasibility of the design.