Porous wicking-material-based two-phase passive cooling is a promising technology for high heat-flux management for its advantage of pumping-free and self-regulating characteristics, which utilizes capillary pressure for coolant delivery in response to the real-time heat flux from the hot spots. In this work, graded copper inverse opals (g-CIOs) material is designed and fabricated with bottom layers of smaller pores and larger pores near the top in the thickness direction. The small pores provide high capillary pressure for liquid delivery, and large pores ensure a low viscous pressure drop. This anisotropic wicking material design overcomes the challenge of dissipating high heat fluxes while scaling up wicking distances by decoupling the permeability and capillary pressure in vertical and lateral directions. g-CIOs material is fabricated with template-assisted copper electrodeposition. We developed a multi-step electrodeposition process with templates made of packed and sintered polystyrene spheres of different sphere sizes to have independent control over the permeability for each layer of different pore sizes. A semi-analytical model based on Darcy’s law is utilized for a parametric study on the impact of total wick thickness and graded pore-size combinations on the critical heat fluxes and wicking distances, illuminating optimizations and design regimes for graded CIOs capable for high heat flux and large area cooling applications.


Design and Fabrication of Graded Copper Inverse Opals (G-Cios) for Capillary-Fed Boiling in High Heat Flux Cooling Applications

Division / Sponsors: 
Electronic & Photonic Packaging Division (EPPD)

Paper Proceedings: https://asmedigitalcollection.asme.org/InterPACK/InterPACK2020/volume/84041

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