Performance test of an ultra-thin flat heat pipe with a 0.2 mm thick vapor chamber

In this paper, a novel ultra-thin flat heat pipe (UFHP) with an active steam chamber of 76 x 46 x 0.2mm(3) is successfully designed, fabricated and tested. The innovation point of the UFHP is its thinner thickness with only 0.65 mm total thickness which can reduce the space for heat dissipation in electronic devices and accommodate its increasingly compact structure. Another innovation point is the design of supporting pillars. It is etched in the UFHP to avoid the ultra-thin chamber deformation and can also supply vertical channels for liquid reflux. Thermal performance is assessed and results reveal that the optimal operating power of the UFHP is 7.1-13.7 W at different tilt angles and liquid filling rates. When the filling rate is 1.05 and the tilt angle is 90 degrees, it has the best performance, and the minimum average thermal resistance is 1.15 degrees C W-1 with the input power varying from 7.1 to 13.7 W. When the input power is 15.9 W and the evaporator temperature is 60 degrees C, the heat transfer performance of the vertically placed UFHP is perfect and with a thermal conductivity of 800 W m(-1) K-1. This research is of great significance for the production of UFHP with ultra-thin thickness and good heat transfer performance.