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New Challenge after the 0.15mm Vapor Chamber: Foldable Vapor Chamber
Keywords: Foldable smartphone, Thermal management, Vapor chamber
Our group and Kelvin Thermal have demonstrated 0.25mm Vapor Chamber in 2015, which was further thinned to 0.20mm in 2017 and 0.15mm in 2018. Our novel cooling solutions are expected to support the advancement of smartphones in the 5G era. We will review this technology evolution, followed by presenting a new challenge and opportunity: foldable vapor chambers for foldable smartphones. We will review a few key concepts taken from approximately 100 US patents on foldable phone by major electronics manufacturers such as Apple, Samsung, LG, Microsoft, etc. Then, we will present our design studies on three possible strategies for thermal management of a simulated foldable smartphone. Three cases are studied: graphite heat spreader, two thermal ground planes (TGP) with a graphite hinge and a single large TGP. TGP is also known as vapor chamber or 2-D flat heat pipe. The design studies were performed using FEM models validated against experimental measurement of the thermal response of two different TGPs at two different input powers. In the fully unfolded configuration, a significant difference is observed between different thermal management strategies. For design using a graphite heat spreader, the temperature distribution across the OLED display is about 13.1C. For the design using two TGPs, the temperature distribution is about 5.4C. Finally, for the design using a single large TGP, the temperature distribution is only 0.8C. These results demonstrate that foldable TGP is the best solution for thermal management of future foldable smartphones.
Ali Nematollahisarvestani, Research Assistant
University of Colorado Boulder
Boulder, CO
United States

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