Air Jet Impingement Cooling of Electronic Devices Using Additively Manufactured Nozzles

This article reports the design, fabrication, and demonstration of additively manufactured air jet impingement coolers for the thermal management of high-power gallium nitride (GaN) transistors. The polymer jet coolers impinge high-speed airflow with a velocity of 42-195 m/s (Reynolds number between 1.87 \times 10^{4} and 8.77 \times 10^{4}) onto working GaN devices mounted on a printed circuit board (PCB). The air jet provides cooling heat fluxes of up to 58.4 W/cm², cooling rates of up to 6.6 °C/s, and convective heat transfer coefficient ranging from 5.2 to 17.0 kW/( \text{m}^{2}\cdot \text{K} ). The cooling performance is comparable to that of jet coolers made from other materials and manufacturing technologies. A key benefit of additive manufacturing (AM) is design freedom and geometric complexity, which we highlight by demonstrating three different packaging configurations, each enabled by a different jet cooler design that is customized for different types of packaging configurations: Cooler 1 directs two parallel impinging jets onto the top side of two devices; cooler 2 directs two air jets onto the front side and two air jets onto the back side of two devices; and cooler 3 directs air jets onto the front side of four devices mounted on parallel adjacent circuit boards. The second benefit of AM is the ability to consolidate multiple components into a single part, which we highlight by combining a nozzle, a fluidic delivery system, and a flow distributor within a volume of 80 mm \times80 mm \times100 mm. This work demonstrates the potential of AM to create complex, lightweight, fluidic delivery systems to achieve thermally and hydrodynamically optimized air jet cooling for high-power-density electronic devices.