Mechanics of interface with applications in electronic packaging

The purpose of this paper is to present a brief review of the mechanics of interface fracture, with a focus on applications in electronic packaging. From a structural mechanics perspective, electronic devices can be thought of as composite structures fabricated from highly dissimilar materials. Often, the interfaces between these materials are where failure is most likely to occur when the device is subjected to thermomechanical loading. The mechanics of interface fracture is a specialized subtopic within the discipline of fracture mechanics and the nonspecialist may be unaware of some of the subtle differences encountered in applying interface fracture concepts. The mechanics associated with interface fracture introduces certain mathematical concepts that may seem to be unnecessarily complicated, but are essential for its proper application. It is important that the electronic packaging reliability engineer be aware of these concepts, understanding the most important implications. This review will focus on the mechanics and computational aspects of interface fracture in electronic structures, with a particular emphasis on some details that the nonexpert could only obtain after an extensive review of the available literature. Numerical results are presented for the important problem of corner cracking between silicon and epoxy materials subjected to thermomechanical loading. These new results provide insight into the three-dimensional nature of interfacial crack propagation at bimaterial corners.