Modelling the Impact of Crystal Orientation on Mechanical Damage of Sac305

The reliability of SAC305 solder joints is largely dependent on the microstructure of the solder joints in microelectronic assemblies, particularly on the anisotropic nature of <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$\beta$</tex>-Sn grains and their crystallographic orientations. This paper explores how crystal orientations across grain boundaries and their arrangements influence mechanical deformation using the Crystal Plasticity Finite Element Method (CPFEM). Three structured case studies are conducted using two different sets of crystal orientations. First, a comparative analysis of SAC3035 deformation behaviour under mechanical shear and tensile loading for the defined sets of orientations is undertaken. Based on these results, mechanical tensile loading is chosen for two additional case studies, to further investigate how different crystal orientations across grain boundaries affect strain accumulation, slip system activation, and stress redistribution. The findings show that higher plastic deformation driven by slip systems activation are strongly influenced by the crystal orientation around the grain boundaries, while the presence of misaligned crystal orientations acts as a barrier to plastic deformation by restricting dislocation movement. The study quantifies the effects of several microstructural configurations in terms of crystalline Lagrangian strain, the accumulated plastic strain, and the activation of crystal slips. It has been highlighted that there are certain favourable arrangements of crystal orientation across grain boundaries that can lead to an improved SAC305 reliability performance.