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8th Thermal and Fluids Engineering Conference (TFEC)
March, 26-29, 2023, College Park, MD, USA

PUMPED, HYBRID TWO-PHASE COOLING SYSTEM FOR HIGH HEAT FLUX ELECTRONICS

Get access (open in a dialog) pages 1181-1188
DOI: 10.1615/TFEC2023.enh.045998

Abstract

Advanced Cooling Technologies, Inc. (ACT) is developing an innovative hybrid two-phase cooling system (HTPCS) that combines the unique benefits of mechanically pumped two-phase systems with capillary-driven two-phase cooling. The HTPCS has several unique evaporator features that separate this system from traditional two-phase cooling systems. First, electronics are mounted to an Aluminum Nitride (AlN) plate that is in direct contact with a region that promotes thin film evaporation on the opposite side of each transistor. Mounting locations are provided using Direct Bond Copper (DBC) traces customized to the applications needs. This arrangement greatly reduces the thermal resistance between the electronics and coolant, which allows for high power and high heat flux management without a large temperature potential. By using a Kovar envelope to which the AlN is attached, all materials are Coefficient of Thermal Expansion (CTE) matched. This prevents stress at the joint between the electronics and evaporator as the electronics increase in temperature during operation. Inside the cold plate, a dielectric coolant, such as a refrigerant, enters through an inlet tube and is exposed to several capillary structures, or wicks. These structures pull liquid a short distance to a specially designed thin film evaporation surface. ACT demonstrated the removal of heat loads >300W/cm² while maintaining device temperatures below 80°C. The concept, design, and test data are discussed in this paper.