As power electronic applications continue to switch higher levels of voltage and current in smaller-sized component packages, the resulting increase in power density requires efficient thermal management. This paper compares the thermal performance for operating a metal-oxide-semiconductor field-effect transistor on a water-cooled pole-arrayed heat sink versus a novel water-cooled microchannel heat sink. Details are presented on an innovative technique using Fourier analysis techniques for determining the thermal capacitance modeling parameter for the heat sinks from experimental data.