Enhancing thermal management of GaN transistors with direct oil jet impingement: Experimental insights for high-power electronics

This study experimentally investigates the cooling performance of oil jet impingement on high-power GaN transistors, focusing on the effects of nozzle geometry (diameter: 0.5 mm, 1 mm; nozzle-transistor distance: 5 mm, 10 mm) and properties of two fluids (a NewOil-A and Siloil M40). At a flow rate of 80 mL/min, Siloil M40 achieved a heat transfer coefficient of 13 848 W/m 2 K, reducing junction temperatures to 120 °C under 38 W power dissipation (corresponding to a heat flux density of 135 W/cm 2 ). In contrast, NewOil-A yielded a junction temperature of 90 °C under identical power and heat flux conditions, demonstrating NewOil-A's superior cooling performance. The optimized system enabled a 198 % improvement in power handling compared to uncooled operation. Smaller nozzles (diameter: 0.5 mm) and reduced nozzle-transistor distance (5 mm) enhanced cooling efficiency. Additionally, a novel correlation linking Nusselt, Reynolds, and Prandtl numbers is proposed, offering practical design guidelines for GaN-based power electronics in applications like electric vehicles.