Insulated Gate Bipolar Transistor (IGBT) is one of the basic electronic components of rail and electric vehicle traction systems. They are used for switching and can perform this task very quickly. Regarding its operation, thermal modelling of IGBT modules is vital for obtaining temperature distribution for these components and thermal resistances of the entire IGBT as well. Nowadays, Computational Fluid Dynamics (CFD) is a robust and advantageous tool for modelling fluid flow and heat transfer problems that can be adopted to the thermal design of such critical components to better understand the effects of the design variables on the thermal-hydraulic performance of IGBT. This study is about conjugate heat transfer in a heat sink with diode and IGBT chips as heat sources and investigates the effect of minichannel porosity on Nusselt number (Nu) and the pumping power at several inlet Reynolds number (Re). The CFD analysis have been conducted parametrically and revealed that with increasing Re, both Nu and pumping powers increased significantly, indicating that heat transfer enhancement as well as power consumption are dominated by the flowrate. It is also shown that low minichannel porosities provide higher Nu and pumping power as well. The parametric studies provided a knowledge about the thermal-hydraulic performance of the IGBT and assisted to understand the effects of the governing parameters on the target functions.