CPV Cell Infant Mortality Study: Preprint

Six hundred and fifty CPV cells were characterized before packaging and then after a four-hour concentrated on-sun exposure. An observed fielded infant mortality failure rate was reproduced and attributed to epoxy die-attach voiding at the corners of the cells. These voids increase the local thermal resistance allowing thermal runaway to occur under normal operation conditions in otherwisedefect-free cells. FEM simulations and experiments support this hypothesis. X-ray transmission imaging of the affected assemblies was not found capable of detecting all suspect voids and therefore cannot be considered a reliable screening technique in the case of epoxy die-attach.