Step-stress accelerated degradation analysis for highly reliable products

Collecting accelerated degradation test (ADT) data can provide useful lifet ime information for highly reliable products if there exists a product qual ity characteristic whose degradation over time can be related to reliabilit y. However, conducting a constant-stress ADT is very costly. This is obviou sly not applicable for assessing the lifetime of a newly developed product because typically only a few test samples (prototypes) are available. To ov ercome this difficulty, we propose a step-stress accelerated degradation te st (SSADT) in this paper. A case study of light emitting diodes data is use d to illustrate the proposed procedure, It is seen that SSADT has several a dvantages over a constant-stress ADT. SSADT not only reduces the experiment al cost significantly, but also provides the reliability analysts an effici ent tool to assess the lifetime distribution of highly reliable products.