Heat Transfer Performance Evaluation of Ultrathin Flexible Heat Pipes with Vapor Channels Formed by Micro-imprint
The manufacturing equipment and fabrication process of ultrathin flexible heat pipe(UFHP)with PMMA casings are introduced in this study.A micro-column array fabricated by a separate micro-imprint mold and a high-temperature sintered multilayer copper mesh are used as vapor channel and wick,respectively,and UFHPs with a thickness of 0.67mm is fabricated.The effects of micro-imprint temperature,pressure,and dwell time on the forming of micro-pillars were studied.The test devices and the experimental methods of the heat transfer performance of UFHPs are introduced.The experimental results showed that the optimal liquid filling amount is 350-400 μL and the highest thermal conductivity reached 924.1 W/(m·K).The thermal conductivity of the UFHP is still 1.16 times that of copper with a bending angle of 90°.In summary,the UFHPs with PMMA casings fabricated by micro-imprint have the advantages of flexible structure,low cost,and low vapor flow resistance,and are an ideal solution to the heat dissipation problem of flexible wearable electronic devices.
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