CPV Cell Infant Mortality Study

Abstract

Six hundred and fifty CPV cells were characterized before packaging and then after a four‐hour concentrated on‐sun exposure. An observed 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 operating conditions in otherwise defect‐free cells. FEM simulations and experiments support this hypothesis. X‐ray transmission imaging of the affected assemblies was found incapable of detecting all suspect voids and therefore cannot be considered a reliable screening technique in the case of epoxy die‐attach.