Numerical simulation of interface delamination - with application to IC packaging

Abstract

Numerical simulation is employed to gain a deeper understanding on interface delamination in IC packages during reflow soldering. Using the vapor pressure incorporated cell element model, the research concentrates on identifying the possible crack initiation mechanisms, and also the crack initiation position along interfaces in a thin quad flat pack (TQFP) and a plastic ball grid array (PBGA) package. For TQFP and PBGA, increased initial porosity and vapor pressure cause rises in the void growth and fall in stress carrying capacity of the cell elements, resulting in weakened interfaces. The regions of intense void growth for both interfaces appear to concentrate near the interface corners. A full field analysis of the overmold in the PBGA package reveals that with the complete delamination of the die/die attach interface, the critically damaged region in the overmold closest to the die attach will undergo cracking, and lead to popcorn failure.