Fracture mechanics analysis of delamination failures in IC packages

This paper describes the application of fracture mechanics to the analysis of delamination in IC packages. An introduction to the fundamentals of interfacial fracture mechanics will first be given together with a description of some numerical methods for calculating fracture mechanics parameters such as strain energy release rate and mode mixity. Fracture mechanics methodology will then be applied to analyze the popcorn cracking failure of moisture-preconditioned plastic-encapsulated IC packages undergoing solder reflow. The effect of moisture in engendering hygrostress and degrading interfacial fracture toughness will be discussed. Simulation of heat transfer and moisture diffusion processes occurring during package qualification will be described. Experiments which verify the methodology for predicting delamination in packages using the fracture mechanics approach will then be presented, followed by some interesting case studies.