The reliability of solder joints is affected significantly by thermomechanical
properties such as creep and thermal fatigue. In this work, the creep of
directionally solidified (DS) Sn-3Ag-0.5Cu wt.% (SAC305) dog-bone samples
(gauge dimension: 10 9 2 9 1.5 mm) with a controlled or fibre
texture is investigated under constant load testing (stress level:  30 MPa) at
a range of temperatures from 20C to 200C. Tensile testing is performed and
the secondary creep strain rate and the localised strain gradient are studied
by two-dimensional optical digital image correlation (2-D DIC). The dominating
creep mechanisms and their temperature dependence are explored at
the microstructural scale using electron backscatter diffraction (EBSD), which
enables the understanding of the microstructural heterogeneity of creep
mechanisms at different strain levels, temperatures and strain rates. Formation
of subgrains and the development of recrystallization are observed
with increasing strain levels. Differences in the deformation of b-Sn in dendrites
and in the eutectic regions containing Ag3Sn and Cu6Sn5 are studied
and related to changes in local deformation mechanisms.
Key words: Pb-free solder, creep, microstructure evolution, recrystallization

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• Evaluating Creep Deformation in Controlled Microstructures of Sn-3Ag-0.5Cu Solder