Morphologies and characteristics of tin whiskers on surface of SnAgCuCe/Er lead-free solder

Large sized CeSn₃ and ErSn₃ phases precipitated in the Sn-3.8Ag-0.7Cu1.0Ce/Er solder alloy are oxidized when they are exposed in air, and tin whiskers can rapidly grow on the surface of the oxidized CeSn₃ and ErSn₃ phase. The growth behavior of tin whiskers formed on the surface of the oxidized CeSn₃ and ErSn₃ phases was investigated.The results indicate that not only traditional cylinder-like tin whiskers but also some special ones are observed on the surface of the oxidized CeSn₃ and ErSn₃ phases, such as stripelike tin whiskers, distorted tin whiskers, tin whisekrs with variable cross sections, branch-type tin whiskers, merging-type tin whiskers and jointing-type tin whiskers and so on.