Heat transfer of vapor chamber with different types of microchannels

Two 40-mm × 35-mm × 1.525-mm micro vapor chambers were fabricated by inductively coupled plasma etching on silicon substrates and tested in this study. One vapor chamber exhibited convergent microchannels, whose widest and narrowest width were 0.3 mm and 0.1 mm, respectively, and the other exhibited discontinuous microchannels having width of 0.3 mm. Those micro vapor chambers that were filled with deionized water in a filling ratio of approximately 48% were tested with various titled angles and input powers. The results showed that the thermal performance of the vapor chamber having discontinuous microchannels was inferior because the spacing between microchannelend and the micropostin both condensing and evaporating sections was too far to return the condensed fluid from condensing section to the evaporating section of the vapor chamber. On the contrary, the convergent microchannel in the other vapor chamber enhanced capillary force, so that the condensed liquid could be successfully forced from the condensing section to the evaporating section even with top heating mode (–90°). The thermal resistance of the vapor chamber having convergent micro channels with top heating mode was 2.08°C/W at 22 W, while the thermal resistance of the vapor chamber with horizontal heating mode was 1.46°C/W at 28 W.