Enhancing Electromigration Resistance of Sn1Ag0.5Cu Solder by Adding Single Ni or Ge Microelement

Abstract

Our previous study has demonstrated that Ni and Ge microelements-added Sn1Ag0.5Cu0.07Ni0.01Ge (SACNG) solder showed a higher electromigration (EM) resistance than Sn1Ag0.5Cu (SAC) solder. However, it is not yet clear whether enhancing the EM resistance of SAC solder is taken by both of Ni and Ge microelements, or taken by single Ni or Ge microelement. This paper investigates the respective effect of single Ni and Ge microelements on the EM resistance of SAC solder. The EM resistances of Sn1Ag0.5Cu0.07Ni and Sn1Ag0.5Cu0.01Ge solders are experimentally compared via the morphological change, which is quantitatively investigated by measuring the ratio of the total EM-induced hillock volume to the time for current supply in a certain area in a sample. The experimental conditions are same as those used for SAC and SACNG solders in our previous study, and the result is analyzed together with the two reported solders mentioned above. It is concluded that single Ni and Ge microelements separately enhance the EM resistance of SAC solder, and adding of both Ni and Ge microelements together further enhances it. A possible mechanism is proposed to explain the investigated effects.