On the electrochemical migration mechanism of tin in electronics

Electrochemical migration (ECM) of tin can result in the growth of a metal deposit with a dendritic structure from cathode to anode. In electronics, such growth can lead to short circuit of biased electrodes, potentially leading to intermittent or complete failure of an electronic device. In this paper, mechanistic aspects of ECM of tin are discussed in detail, using experimental results on ECM of tin in various environments and varying potential bias. Results on the formation of local pH changes by the electrodes and experiments observations are combined with thermodynamic stability of tin species as depicted in the Pourbaix diagram.

► The mechanism of electrochemical migration of tin in electronics is described.
► Examples from experiments in various environments are given.
► Strong pH gradients are found in the electrolyte, between the electrode terminals.
► Stability of tin species in the pH domains are crucial for the formation of tin dendrites.
► Migration is an interplay between reaction dynamics and ionic contaminants in solution.