Design and solderability characterization of novel Au-30Ga solder for high-temperature packaging

摘要

To meet the needs of high-temperature packaging for high-power devices, a novel Au-30Ga solder was designed and prepared, and its solderability was characterized in this work. The results showed that it was a eutectic alloy with a melting point of 450 °C, consisting of AuGa phase and AuGa_2 phase. The novel Au-30Ga solder possessed high thermal conductivity, excellent wettability and higher working temperature than traditional Au-based solders. The shear strength of Au-30Ga/ Ni joint can reach 77.1 MPa, which was much higher than that of Au-20Sn/Ni and Au-12Ge/Ni joints. The addition of a trace amount of Ni helped to enhance the shear strength of the Au-30Ga/Ni joint, but had no significant effect on the micro-structure of the Au-30Ga/Ni joint. Two Ni-Ga intermetallic compound layers were formed at the Au-30Ga/Ni interface, which thickened with an increase in soldering time. In addition, a new Au_7Ga_3 phase would be observed in the seam when the re flow time was more than 5 min.