Abstract:

Grain morphology of SnAgCu (SAC) solder alloys is known to evolve throughout their life due to recrystallization caused by mechanical and/or thermal cycling. Changes in grain morphology affect the overall anisotropic mechanical behavior of few-grained (oligocrystalline) SAC solder joints. The recrystallization occurs preferentially and locally in high deformation regions in solder joints, resulting in the formation of small grains and new grain boundaries. This behavior has been studied experimentally by different researchers and various attempts have been made to model the recrystallization in solder joints under different cycling conditions. The objectives of this article are to: (i) demonstrate a procedure for explicit modeling of recrystallization in critical regions of anisotropic oligocrystalline solder joints, using multi-level nested Voronoi tessellation techniques; and (ii) demonstrate the effects of the recrystallization on solder joint creep response, using anisotropic Hill-Garofalo representation of each grain and an isotropic Mises-Garofalo representation of the intervening grain boundaries.

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