Finite element based three dimensional crack propagation simulation on interfaces in electronic packages

Interface delamination phenomenon has been a great concern for semiconductor package reliability. In order to better understand the package failure mechanisms, crack initiation and propagation behavior of interface flaws have to be investigated in detail. In this paper, three dimensional interface crack propagation is examined using the enriched finite element method. A fatigue crack growth simulation technique, which has been widely studied in the literature to predict steady state crack growth behavior after crack initiation in homogeneous materials, is extended to three dimensional interface cracks. The method described uses a modified version of the classical fatigue crack growth rate "law" developed by Paris and Erdogan to simulate stable crack growth under cyclic loading conditions, with the crack constrained to the plane of the interface. The crack driving force, which is chosen as cyclic strain energy release rate, is calculated using the enriched finite element method. As a practical example in semiconductor package reliability analysis, the method is used to simulate the propagation of a three-dimensional interface crack on a silicon/epoxy interface under various loading conditions. Plots of advancement of the crack front and the changes in total strain energy release rates as the crack shape evolves during propagation are also given. Lastly, crack propagation simulation is demonstrated for a generic package model using a submodeling technique.