The ever-increasing need for power consumption in electronic devices, coupled with the requirement for thinner size, calls for the development of efficient heat spreading components. Vapor chambers (VCs), because of their ability to effectively spread heat over a large area by two-phase heat transfer, seem ideal for such applications. However, creating thin and efficient vapor chambers that work over a wide range of power inputs is a persisting challenge. VCs that use wicks for circulating the phase changing media, suffer from capillary restrictions, dry-out, clogging, increase in size and weight, and can often be costly. Recent developments in wick-free wettability patterned vapor chambers replace traditional wicks with laser-fabricated wickless components. An experimental setup allows for fast testing and experimental evaluation of water-charged VCs with liquid-assisted cooling. The sealed chamber can maintain vacuum for long durations, and can be used for testing of very thin wick-free VCs. This work extends our previous study by decreasing overall thickness of the wick-free VC down to 3 mm and evaluates its performance. Furthermore, the impact of wettability patterns on VC performance is investigated, by carrying out experiments both in non-patterned and patterned VCs. Experiments are first carried out on a wick-free VC with no wettability patterns and comprising of an entirely superhydrophilic evaporator coupled with a hydrophobic condenser. Thereafter, wettability patterns that aid the rapid return of water to the heated site on the evaporator and improve condensation on the condenser of the vapor chamber are implemented. The thermal characteristics show that the patterned VCs outperform the non-patterned VCs under all scenarios. The patterned VCs exhibit low thermal resistance independent of fluid charging ratio withstanding higher power inputs without thermal dry-outs.

翻译：电子设备功耗的持续增长以及对更薄尺寸的需求，推动了高效散热组件的发展。均温板因其能够通过两相传热在大面积上有效散热的特性，似乎非常适合此类应用。然而，制造可在宽功率输入范围内工作的薄型高效均温板仍是一个持续存在的挑战。使用毛细芯循环相变介质的均温板存在毛细限制、干涸、堵塞、尺寸和重量增加等问题，且通常成本高昂。近年来无芯润湿性图案化均温板的进展，用激光制造的无芯组件替代了传统毛细芯。一种实验装置可对带液冷辅助的充水均温板进行快速测试和实验评估。密封腔体可长时间维持真空，并可用于测试极薄的无芯均温板。本研究通过将无芯均温板的总厚度降至3毫米，扩展了前期工作并评估其性能。此外，通过在无图案和图案化均温板上进行实验，研究了润湿性图案对均温板性能的影响。实验首先在无润湿性图案的无芯均温板上进行，其蒸发器完全为超亲水表面，冷凝器为疏水表面。随后，在蒸发器上实施有助于水快速回流至加热区域、在冷凝器上改善凝结的润湿性图案。热特性表明，在所有场景下，图案化均温板的性能均优于无图案均温板。图案化均温板表现出较低的热阻，且不依赖于充液率，能够承受更高的功率输入而不会发生热干涸。