Mg₂Sn-induced whisker growth on the surfaces of Mg/Sn/Mg ultrasonic-assisted soldering joints

In this paper, the phenomena of Mg₂Sn-induced Sn whisker growth were explored on the surfaces of Mg/Sn/Mg ultrasonic-assisted soldering joints after aging treatment. The in-situ observation and thermal analysis confirmed that the formation and the corrosion of Mg₂Sn nanoparticles were the dominant reason of Sn whisker growth. The Mg₂Sn accumulation at the grain boundaries would pin the dislocation slip and affect the continuity of whisker growth, and the boundary angle would thus play a decisive role in the growth shape of Sn whiskers due to the pining effect of Mg₂Sn. This study might be conducive to elucidating the growth behavior of Sn whiskers and provide the exploration strategy to further improve the bonding strength of Mg/Sn/Mg ultrasonic-assisted soldering joints.