The surface energies of β-Sn — A new concept for corrosion and whisker mitigation

Abstract

Corrosion data provided under high-temperature and high-humidity conditions as well as tin whisker growth studies are explained by differences in the surface energy of lattice planes within the crystal structure of β-tin. For this purpose, electrodeposited tin finishes were investigated regarding their microstructure utilizing X-ray diffraction, cross-sectional SEM and EBSD analysis. The corrosion as well as the tin whisker propensity strongly depends on the preferred orientation of the surface finishes. With an increasing texture along the (211) lattice plane a decreasing corrosion and whisker propensity was observed, in contrary, the presence of the (101) and (112) textures results in an increased corrosion and whisker propensity. The maximum whisker length was reduced by one order of magnitude by changing the preferred orientation towards the (211) lattice plane of the tin finish. Modified embedded-atom method simulations of tin surfaces demonstrate the minimization of the surface energy of (211) surfaces, whereas the surface energies of the (101) and (112) Miller planes are increased. We find a strong connection between the minimization of surface energy and the corrosion and tin whisker propensity of electrodeposited tin finishes. To our best knowledge, this is the first study connecting the influence of the electrodeposition parameters on the corrosion and whisker propensity explained by calculations of the surface energies of

Effect of Cu Substrate Roughness and Sn Layer Thickness on Whisker Development from Sn Thin-Films

“…Jagtap et al [17] reported that whisker growth is more likely from the Sn grains with lower indices, like <100> or near-<100>, than from higher ones, like <321>. Eckold et al [18] showed similar results, that the <211> orientation is a preferred orientation because this orientation ensures lower corrosion propensity than the <220> or <321>. Zhang et al [19] reported that whisker susceptibility is generally low in Sn layers with multi-peak texture (like <112> <101> <103>).…”

The influence of the crystallographic structure of the intermetallic grains on tin whisker growth

“…Eckold et. al found that in Sn layers the preferred orientation of grains is <211>, because grains with such orientation have lower corrosion and tin whisker susceptibility than grains with <321> or <220> orientation [17]. However, Zhang et.…”

Isotropic Sodiation Behaviors of Ultrafast-Chargeable Tin Crystals

“…Although this two-stage sodiation process was observed in all three different diffusion couples, a slight difference is observed at the very beginning of the reaction; the first-stage Na diffusion, as characterized by the amorphization of c-Sn, is slower for the Na/Sn⟨101⟩ diffusion couple. This is probably because of the comparatively stable nature of the (101) surface of the Na/Sn⟨101⟩ diffusion couple. , However, after this initial amorphization stage, the amorphous structures of the interfaces become similar regardless of the orientation of c-Sn; this weakens/nullifies the directionality of Na diffusion and promotes isotropic diffusion, explaining the mechanistic origin of isotropic swelling (Figure ).…”

“…This is probably because of the comparatively stable nature of the (101) surface of the Na/Sn⟨101⟩ diffusion couple. 54,55 However, after this initial amorphization stage, the amorphous structures of the interfaces become similar regardless of the orientation of c-Sn; this weakens/nullifies the directionality of Na diffusion and promotes isotropic diffusion, explaining the mechanistic origin of isotropic swelling (Figure 2).…”