**6. Conclusions**

gy amplification factors introduced in Section 4.5.3 were used to increase the energy around

**Figure 12.** *a*), (*b*), and (*c*) are experimentally observed microstructures of the same location; (*d*), (*e*), and (*f*) are simulat‐

A micrograph from a normal thermal cycling test was used to verify the simulation results (see Fig. 13 (a)). The sample was examined after 5000 TCs and the micrograph was taken from the center of the cross section. The major IMPs were highlighted in Fig. 13 (a) for easy recognition and Fig. 13 (b) was used as the initial microstructure for the microstructural sim‐ ulation. As compared with in situ samples, solder interconnections in normal thermal cy‐ cling tests experience moderate plastic deformation, and thereby, require long incubation

Four snapshots (after 1500, 3000, 4000, and 5000 TCs respectively) of the simulated micro‐ structural evolution are presented in Fig. 14. Since there are no interfaces and pre-existing grain boundaries in the calculation domain, the intermetallic particles are the most favorable sites for nucleation in this case. The particle stimulated nucleation is shown in the simula‐ tion results and the initiation of recrystallization near the IMPs is clearly visible in Fig. 14 (a). The growth of the new grains at the expense of the strain-hardened matrix is presented in Fig. 14 (b)-(*d*). After 4000 TCs, since the whole matrix is consumed by the recrystallized

ed microstructures after 500, 1000, and 1500 thermal cycles respectively [39].

time for recrystallization.

the IMPs.

108 Recent Developments in the Study of Recrystallization

In this chapter, the current understanding of the microstructural changes in solder intercon‐ nections was introduced, followed by a brief review of the Monte Carlo simulations of grain growth and recrystallization. A new algorithm for predicting dynamic recrystallization in solder interconnections during thermal cycling tests was presented. The algorithm was real‐ ized by combining a Potts model based Monte Carlo method and a finite element method. The correlation between real time and MC simulation time was established with the help of the in situ test results. Recrystallization with the presence of intermetallic particles in solder matrix was simulated by introducing the energy amplification factors in the particle-affected deformation regions. The algorithm predicts the incubation period of the recrystallization as well as the growth tendency of the recrystallized region, which are in good agreement with the experimental findings. Although the research for the microstructural simulation of sol‐ der interconnections is still at its primary stage, the presented algorithm shows potential for better reliability assessment of solder interconnections used in the electronics industry.

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Simulation of Dynamic Recrystallization in Solder Interconnections during Thermal Cycling

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