Electromigration effect upon the Sn/Ag and Sn/Ni interfacial reactions at various temperatures

Abstract

This study investigated the effects of the passage of electric currents of 500 A/cm2 density through Sn/Ag couples annealed at 120 and 160 °C. The results showed that when the direction of electron flow was from the Sn side to Ag, it enhanced the growth of the Ag3Sn phase at the interface, and it retarded the Ag3Sn phase growth when the electrons flowed from the Ag side to Sn. Similar results were found in the Sn/Ni system. The Ni3Sn4 phase formed in the Sn/Ni couples annealed at 160 and 180 °C. The growth rate of the Ni3Sn4 phase increased when the electrons flowed from the Sn side to Ni side, and decreased if the direction of electron flow was reversed. The thickness of the reaction layers was measured, and the apparent effective charges za∗ for Sn were determined. The values of za∗ decreased with increasing temperatures, which indicated that the effect of electromigration on interfacial reactions became less significant at higher temperatures.