Thermal analysis of Silicon Carbide (SiC) power semiconductor packages is a crucial design step to ensure highly reliable device performance at elevated temperatures. The square-root-t extrapolation method is widely adopted to approximate the temperature development within the SiC die for short time transients when device temperature measurements cannot be performed. The reduced thermal resistance of the SiC die leads to smaller thermal time constants. Therefore, the approximation of the heat propagation in SiC devices also has to include the die attach. This paper analyzes the thermal behavior of SiC power semiconductor packages by means of comprehensive FEM simulations, allowing to more precisely determine the error of the temperature estimation based on the square-root-t approximation for SiC power devices. © 2021 IEEE.