Tin whiskers formation in Sn₀.₇Cu₀.₀₅Ni₁.₅Bi under electro-migration stressing

Stress induced by electrical current testing indeed has caused the formation of many whiskers growth in soldering applications. The aim of this investigation is to investigate the electrical current testing to the formation of whiskers. Also the mitigation could be achieved with the additional element of Nickel-Bismuth (Ni–Bi). Characterization of whisker growths are evaluated using the Scanning Electron Microscopy (SEM) on the deposits near anode and cathode areas. Synchrotron micro-XRF were performed on Sn₀.₇Cu₀.₀₅Ni₁.₅Bi at anode and cathode to accurately observe the distributions of elements in the sample. The obtained results demonstrate that the whisker growths with the effect of current stressing is associated with the intermetallic compound (IMCs) thickness on the anode and cathode areas. Finding shows that by addition of Ni-Bi elements can help to reduce the amount of whiskers form by refining the IMCs formation.