Reliable HT electronic packaging — Optimization of a Au-Sn SLID joint

Au-Sn solid-liquid-interdiffusion (SLID) bonding has proven to be a favorable die attach and interconnect technology for high temperature (HT) applications. In combination with silicon carbide (SiC) devices, Au-Sn SLID bonding has potential to be a key technology in future HT electronic systems. In this paper an optimized HT Au-Sn SLID joint is presented. Finite element analysis (FEA) were performed to design an optimized Au-Sn SLID joint for a HT Cu / Si3N4 / Cu / NiP / Au / Au-Sn / Au / Ni / Ni2Si / SiC package (representing a SiC transistor assembled onto a Si3N4 substrate). The optimized package (minimized residual stress at application temperature) was fabricated and investigated experimentally. The bond strength of the optimized joint was superb, with an average die shear strength of 140 MPa. An optimization of bonding time (1–10 min), temperature (290–350 °C) and atmosphere (ambient air, vacuum) was performed. Superb joints were fabricated at a bonding time of 6 min, and a bonding temperature of 300 °C, demonstrating an efficient, industry-feasible Au-Sn SLID bonding process.