The wettability and interfacial reaction thermodynamics and dynamics of novel rare-earth-containing lead-free solders in IGBT packaging were studied. Trace additions of rare-earth element have been shown to refine the microstructure and inhibit interface reaction rate, resulting in the interface layer thickness reduction, thus improving its mechanical properties. This paper investigated the effect of the addition of Ce on the wetting behavior, interfacial reaction thermodynamics and dynamics and microstructure of Sn3.0Ag0.5Cu (SAC305) alloy. Interfacial reaction thermodynamic and dynamic properties are studied by Kissinger method and DSC analysis. The effect of soldering layer defects on IGBT module heat dispersion was simulated and analyzed by ANSYS finite element method. Due to the joint voiding could increase the total thermo-mechanical stress, the addition of Ce into the SAC305 solder reduces the voiding and total thermal resistance, the joint mechanical properties and IGBT module life expectancy can be expected to be improved accordingly.