Modeling interface fracture in flip chip assembly

A flip chip assembly with underfill delamination subjected to thermal cycling loading was investigated using the finite element method and interface fracture mechanics. Numerical evaluation of the mixed mode stress intensity factors and mode mixing parameter for interface cracks located at the silicon/underfill and silicon/FR4 interfaces was carried out. Four types of delamination conditions in flip chip assembly were modeled. The variation of mode mixing and stress intensity factors along with crack length and the variation within a whole thermal cycle are analyzed. The comparison of the results between different conditions is also presented.