Step-stress accelerated degradation analysis for highly reliable products

Collecting accelerated degradation test (ADT) data can provide useful lifetime information for highly reliable products if there exists a product quality characteristic whose degradation over time can be related to reliability. However, conducting a constant-stress ADT is very costly. This is obviously not applicable for assessing the lifetime of a newly developed product because typically only a few test samples (prototypes) are available. To overcome this difficulty, we propose a step-stress accelerated degradation test (SSADT) in this paper. A case study of light emitting diodes data is used to illustrate the proposed procedure, It is seen that SSADT has several advantages over a constant-stress ADT. SSADT not only reduces the experimental cost significantly, but also provides the reliability analysts an efficient tool to assess the lifetime distribution of highly reliable products.