Gallium Liquid Metal Embrittlement of Tin-based Solder Alloys

We report on the embrittlement of tin (Sn)-based solder by liquid gallium (Ga). Exposure to liquid Ga results in a degradation of the intrinsic mechanical properties of the solder due to its ductile-to-brittle transition. Important changes in the solder microstructure accompany this degradation and are predominantly associated with a spontaneous recrystallization of Sn during Ga diffusion into the solder. A detailed investigation of the solder microstructure evolution identifies the recrystallization process as a Continuous Static Recrystallization (C-SRX). Taking into account mechanisms of atomic transport as well as the creation and propagation of defects, a novel liquid metal embrittlement (LME) model is herein proposed, namely the Diffusion-Induced Recrystallization Evolution (DIRE) model.