Electroplating has been implemented in the fabrication of radio frequency circuits for many years. Combined with a photolithography process, this technology can be employed to precisely define both the particle size and distributions of copper wick structures in a phase-change heat transfer system. In this paper, two electroplated copper wick structures are developed to investigate characteristics of phase-change heat transfer at the early phase-change stage when applied heat flux is below . Using subcooled operating fluid, both visualization and heat transfer characterization indicate that the appearance of the onset of nucleation boiling plays a critical role in the transitions of the heat transfer model. Before the onset of nucleation boiling is triggered, heat transfer is dictated by the heat conduction of the wick, as well as evaporation on the meniscus interface. After the onset of nucleation boiling, the heat transfer coefficient is rapidly enhanced by boiling and evaporation within the wick structures. On the characterization curves of heat flux versus the substrate temperature, the wick properties, such as porosity, directly affect the onset of the nucleation boiling location. Submicrometer porous structures existing on electroplated copper pillars expedite the onset of nucleation boiling and enhance the heat transfer coefficients of the phase change.
Transitions of Heat Transfer Modes on Microfabricated Copper Wick Structures
Journal of Thermophysics and Heat Transfer ; 29 , 4 ; 820-825
2015-01-05
6 pages
Aufsatz (Zeitschrift)
Elektronische Ressource
Englisch
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