Ag-Sn Transient Liquid Phase Bonding for High Temperature Electronic Packaging: Effect of Ag Content

Transient liquid phase (TLP) bonding is a promising solution for high temperature (HT) electronic devices as high-quality bonds can be formed at a temperature much lower than the melting point of the resulted joint. In this work, Ag-rich Ag-Sn TLP bonding was evaluated as a potential die attach solution for HT (250 °C) electronic applications. The influence of varying the Ag content on the mechanical strength of the Ag-Sn TLP joint was investigated through room temperature (RT) and HT shear tests. The study was complemented with X-ray imaging of any void formation, and scanning electron microscope (SEM)/energy-dispersive X-ray spectroscopy (EDX) spectra for composition and morphology analysis. It is shown that the Ag-rich joint comprises Ag and Ag3Sn intermetallic compound (IMC), and no obvious void was observed. The shear strengths of the joints measured at both RT and 250 °C have satisfied the requirement for HT applications. In addition, the fractured surfaces after the shear test showed that the failure of Ag-rich joints occurred mostly in the Ag3Sn IMC region. Furthermore, the shear strength improved with increasing Ag content (up to 81.5 at.%) in the bond.