Methodology for DIC-based evaluation of the fracture behaviour of solder materials under monotonic and creep loadings

Abstract

New lead-free solder alloys for electronic packaging contain doping elements conferring upon them improved properties in terms of ease of processibility and strength under high temperature operation conditions. Studies on their resistance to quasi-static rupture remain however relatively limited. In this work, the SAC-based solder alloy, known as InnoLot, is considered and its rupture under monotonic and creep loadings is investigated experimentally and numerically. The Digital Image Correlation (DIC) technique is employed to evaluate the stress intensity factor, as well as the J- and C(t)-integrals, from full-field measurements on notched specimens. The numerical formulations of the theoretical concepts for computation of the physical fracture quantities are provided in the framework of the DIC algorithm. Results derived from the DIC experiments are compared with predictions given by finite element models, and good agreement is found in general. The observed discrepancies can be explained by lack of resolution of the optical setup measurements in the infinitesimal strain regime or by uncertainty associated with the identified material parameters used in the evaluation of stresses from the acquired strains.