High heat flux two-phase cooling of electronics with integrated diamond/porous copper heat sinks and microfluidic coolant supply

Abstract

We here present an approach to cooling of electronics requiring dissipation of extreme heat fluxes exceeding 1 kW/cm2 over ∼1 cm2 areas. The approach applies a combination of heat spreading using laser micromachined diamond heat sinks; evaporation/boiling in fine featured (5 µm) conformal porous copper coatings; microfluidic liquid routing for uniform coolant supply over the surface of the heat sink; and phase separation to control distribution of liquid and vapor phases. We characterize the performance of these technologies independently and integrated into functional devices. We report two-phase heat transfer performance of diamond/porous copper heat sinks with microfluidic manifolding at full device scales (0.7 cm2) with heat fluxes exceeding 1300 W/cm2 using water working fluid. We further show application of hydrophobic phase separation membranes for phase management with heat dissipation exceeding 450 W/cm2 at the scale of a single extended surface (∼300 µm).