Multiscale Simulation of Microstructural Changes in Solder Interconnections During Thermal Cycling

Abstract

It has been observed that, under cyclic thermal loading conditions, the as-solidified microstructures of solder interconnections composed of a few large colonies are transformed into more or less equi-axed grains by recrystallization. These recrystallized microstructures provide continuous networks of grain boundaries through solder interconnections, and, consequently, they offer favorable paths for cracks to propagate intergranularly. In this work a quantitative multiscale method, combining the Monte Carlo (MC) and finite element (FE) methods, was developed for the first time to predict the recrystallization and grain growth in solder interconnections. This method can be used to establish a lifetime prediction model that is based on these microstructural changes. The inhomogeneous nucleation model was employed in the MC model, while the non-uniform stored energy distribution was scaled from the FE model results. The assumption that, during thermal cycling 5% of the work in the interconnections is stored as energy, gives results that are in agreement with experimental observations. The method predicts well the incubation period and the growth rate of the recrystallization as well as the expansion of the recrystallized region.

The role of microstructure in the thermal fatigue of solder joints

“…In Fig. 10b , all joints show a strong correlation between the measured damage (area fraction with MO > 8°) and the simulated peaks in SED, consistent with local peaks in SED being the driving force for recrystallisation 47 , 52 , 53 and fatigue crack nucleation 48 – 50 . Comparing the simulations and experiments in Figs.…”

A Mechanistic Thermal Fatigue Model for SnAgCu Solder Joints

“…[40][41][42][43][44] However, the steady-state dislocation structure generated during the low-temperature dwell remains stable after a few minutes 37 even though the work there continues to increase. Anyway, as we shall see, it appears that the contribution of the low temperature to the overall rate of recrystallization is in fact minor.…”

Fatigue Reliability Analysis of Sn–Ag–Cu Solder Joints Subject to Thermal Cycling

“…The reduced microhardness makes the deformation and subsequent intergranular cracking concentrate in the recrystallized microstructure [43]. Li et al [44] developed a new method to predict the onset and progress of recrystallization in solder interconnection under TC test by combining the FE simulation and Monte Carlo (MC) method. The stored energy distribution from FE simulation was mapped onto the MC model to predict the onset and progress of recrystalliztion.…”