Determining the most likely site and mode of thermomechanical failure in multi-material systems

Abstract

A methodology for predicting sites and modes of thermomechanical failure in IC and MEMS packages is developed. Singular stress fields around several stress concentration locations in a typical plastic-encapsulated IC package are calculated using special variable-order singular boundary elements and the singular value decomposition method. The strain energy density distributions around all the stress concentration locations are then obtained from the singular stress fields and compared. The most likely failure site as the temperature of the package is raised is then determined as well as the likely modes of failure, ie interfacial delamination or cracking of mold compound.