Design and Fabrication of a Large Area Ultrathin Vapor Chamber Based on Print-Wick-Structuring Technology

We explore a large area ultrathin vapor chamber (UTVC) with special wick structures. At present, the thickness of the UTVC applied to mobile electronic devices is usually above 0.3 mm. In this article, the UTVC with a thickness of 0.2 mm and an area of more than 5000 mm2 is designed and fabricated by the print-wick-structuring (PWS) combo technology. We screen print several types of paste on the copper-etched sheet to form the specific wick structures, which greatly influences the heat transfer performance. Thus, the limitation of the traditional copper mesh wick technology in two-phase flow transportation and circulation in a large area and ultranarrow space is solved. The wick structures formed at the sintering temperature of 780 °C enable the working fluid to flow through a 60-mm path in 6 s. The test results show that the UTVC can transfer a heat load of up to 5 W and the temperature difference between the evaporator and condenser can be controlled to 2.5 °C so that the thermal resistance can reach 0.5 °C/W. In addition, the manufacturing process introduced in this article makes the UTVC feasible for mass production.