Antenna consisting of multiple semiconductor transmit/receive modules(TRMs) is the most important feature for active electronically scanned array (AESA) radar. AESA radar uses multiple TRMs belonging to antenna in order to trasmit and receive RF signals and generates various types of radar beams which make it possible to search, track, map terrain, etc. simultaneously. Semiconductor chips in TRM for RF signal processing make significant heating occurs. Heat made by TRMs is removed by cooling plate in which cooling path is formed. In this study, shape and cross-sectional aspect ratio of cooling path which are the main factors affecting thermal performance are analyzed.