Suppression of electromigration failure in Ni added Sn-30Bi solder composite as thermal interface material

This research work investigates the effect of nickel addition (Ni) on electromigration failure resistance of lead-free solder alloy Sn–30Bi as a thermal interface material. Sn–30Bi is a potential solder suitable to be utilized as thermal interface material; however, its electromigration failure resistance under high current density are yet to explored. In the present work, the authors investigated the effect of progressive Ni addition i.e., 0.25, 0.5, and 1.0 wt.% on the microstructural evolution, thermal properties, tensile properties and electromigration behavior of the solder composites. Optical microscopy and field emission scanning electron microscopy were used to study the microstructural evolution, and elemental analysis was performed using energy dispersive spectroscopy. Simultaneous thermogravimetry-differential scanning calorimetry was used for the analysis of thermal properties of the solder alloys. After measuring tensile properties, finally, a custom-made electromigration test rig was used to investigate electromigration behavior at varying current densities. From these tests, the Sn–30Bi–0.5Ni alloy demonstrated superior electromigration failure resistance, and it seems therefore to be a very promising candidate for high-reliability thermal interface material applications.