Multi-scale plasticity homogenization of Sn-3Ag-0.5Cu: from \beta-Sn micropillars to polycrystals with intermetallics

TL;DR

This study combines experimental micropillar testing and crystal plasticity modeling to understand the microstructure-sensitive mechanical behavior of Sn-3Ag-0.5Cu alloys across scales, from single crystals to polycrystals with intermetallics.

Contribution

It introduces a multi-scale homogenization approach linking single crystal slip behavior to polycrystal properties in Sn-based solders, validated by experiments.

Findings

Slip strength and rate sensitivity of key slip systems identified.

Predicted temperature- and rate-dependent behavior matches experimental data.

Mechanistic insights into microstructure-sensitive thermomechanical response of solder alloys.

Abstract

The mechanical properties of $\beta$-Sn single crystals have been systematically investigated using a combined methodology of micropillar tests and rate-dependent crystal plasticity modelling. The slip strength and rate sensitivity of several key slip systems within $\beta$-Sn single crystals have been determined. Consistency between the numerically predicted and experimentally observed slip traces has been shown for pillars oriented to activate single and double slip. Subsequently, the temperature-dependent, intermetallic-size-governing behaviour of a polycrystal $\beta$-Sn-rich alloy SAC305 (96.5Sn-3Ag-0.5Cu wt%) is predicted through a multi-scale homogenization approach, and the predicted temperature- and rate-sensitivity reproduce independent experimental results. The integrated experimental and numerical approaches provide mechanistic understanding and fundamental material properties of microstructure-sensitive behaviour of electronic solders subject to thermomechanical loading, including thermal fatigue.