In-situ reliability analysis of solder joint by digital image correlation

A digital speckle image correlation system was developed to measure the in-situ micro-deformation of the solder joints in a flip chip on board (FCOB) assembly subject to thermal cycling. A pair of digital images acquired from an undeformed and deformed solder joint at certain temperature were correlated using a cross-search algorithm. As a result, deformation distributions in the solder joint were determined. Based on solder material's viscoplastic and underfill material's viscoelastic constitutive models, a finite element model was established to simulate the deformation of the assembly. The measurement results by correlation were then compared with the simulation results. It was found that U and V displacement fields of the solder joint obtained from the experiment and simulation are comparable.