Review of shelf life evaluation methods and a physics of failure approach for shelf life estimation for electronic components

Abstract

Long term storage reliability or shelf life is not well understood in the electronic industry. In this article, we identified inconsistent shelf life interpretations used in the electronics industry and inadequacies of recommended shelf live values and shelf life evaluation methods in standards, manufacturers' documents and in the literature. A Physics of Failure (PoF) shelf life estimation approach that applies to most storage-induced mechanisms in electronic components is developed. In this approach, storage induced mechanisms are categorized into three main groups: 1) storage mechanisms that continues into use conditions, 2) storage mechanisms that affect usability of a component and 3) storage mechanisms that triggers other failure mechanisms under subsequent life cycle stresses. Failure Mechanism, Mode and Effect Analysis (FMMA) taking into account both storage and use conditions of the component is first performed to select the most critical storage induced mechanism. Depending on the mechanism and its category, physics of failure model and acceptance criteria can be selected for shelf life estimation. This approach is demonstrated with electrolyte evaporation in electrolytic capacitors and moisture diffusion induced delamination in plastic encapsulated components.