Experimental research demonstrates the performance of electronic devices on plate fin heat sinks in order to guarantee that operating temperatures are kept as low as possible for reliability. Paraffin wax (PCM) is a substance that is used to store energy and the aluminum plate fin cavity base is chosen as a Thermal Conductivity Enhancer (TCEs). The effects of PCM material (Phase shift material), cavity form base (Rectangular, Triangular, Concave and Convex) with PCM, Reynolds number (Re= 4000-20000) on heat transfer effectiveness of plate fin heat sinks were experimentally explored in this research. The thermal performance of concave base plate fin heat sink with PCM is increased up to 7.8% compared to other cavity base heat sinks.