The Role of Lengthscale in the Creep of Sn-3Ag-0.5Cu Solder Microstructures

Creep of directionally solidified Sn-3Ag-0.5Cu wt.% (SAC305) samples with near-<110> orientation along the loading direction and different microstructural lengthscale is investigated under constant load tensile testing at a range temperatures. The creep performance improves by refining microstructure, i.e. decrease in secondary dendrite arm spacing ({\lambda}2), eutectic intermetallic ({\lambda}e) compound (IMC) size, indicating as longer lifetime, lower strain rate, change activation energy (Q) increase ductility homogeneity macro- micro-structural deformation samples. dominating mechanism obstacle-controlled dislocation room temperature transits to lattice-associated vacancy diffusion elevated (T/T_M > 0.7 0.75). mechanisms are using electron backscatter diffraction (EBSD) heterogeneity identified between b/-Sn dendrites regions containing Ag3Sn Cu6Sn5 particles. size recrystallised grains modulated dendritic spacings, however, recrystalised for coarse-scaled (largest {\lambda}2 {\lambda}e) only localised next IMCs without growth size.