Thermo-Mechanical Characterization of Au-In Transient Liquid Phase Bonding Die-Attach

Semiconductor die-attach techniques are critically important in the implementation of high-temperature wide-bandgap power devices. In this paper, thermal and mechanical characteristics of Au-In transient liquid phase (TLP) die-attach are examined for SiC devices. Samples with SiC diodes TLP-bonded to copper-metalized silicon nitride substrates are made using several different values for such fabrication properties as gold and indium thickness, Au/In ratio, and bonding pressure. The samples are then characterized for die-attach voiding, shear strength, and thermal impedance. It is found that the Au-In TLP-bonded samples offer a high average shear strength of 22.0 kgf and a low average thermal impedance of 0.35 K/W from the device junction through the substrate. It is also discovered that some of the fabrication properties have a greater influence on the bond characteristics than others. Overall, TLP bonding remains promising for high-temperature power electronic die-attach.