In this paper, quantitative microstructure studies were performed on multiple length scales to investigate effect of La doping on SnAg lead free solder materials. Variables considered in this paper include doping amount, aging temperature and aging time. It was found that La doping refines the microstructure and reduces microstructure coarsening rate, but the inter-particle spacing remains unaffected. Therefore, higher La doping level leads to higher volume fraction of the eutectic phase due to the increased total number of Ag_3Sn particles.
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