Characterization and simulation of delamination on package-level considering sub-critical interfacial fracture-parameters under cyclic loading.

Abstract

Delamination is a significant risk to the reliability of optical sensor packages. This is especially the case when undergoing reliability stress tests, such as cyclic loading. Characterization of the fatigue behavior of different materials in use is difficult challenging due to the limited access to samples that represent the actual packaging process. To address this challenges, a special fatigue bending test setup was used to generate crack growth characteristics for the interface between silicon tiles and non-conductive die-attach adhesive. A virtual crack closure technique was applied to calculate the strain energy release rate using the finite element method. Using the data, a fatigue crack growth rate curve was generated, to show the sub-critical crack propagation and determine the constants of Paris’ law. In addition, successfully conducted tests on samples to analyze the interface between injection-molded liquid crystal polymer to nonconductive adhesive and silicon tiles to Ag-filled conductive adhesive are presented in this work.