Design, development and tests of high-performance silicon vapor chamber

This paper presents a novel triple stack process to develop an all-silicon thermal ground plane (TGP) vapor chamber that enables fabrication of compact, large scale, low thermal expansion coefficient mismatch and high-performance heat transfer devices. The TGP vapor chamber is formed through bonding three etched silicon wafers. On both the top and bottom wafers, microscale and high aspect ratio wick structures are etched for liquid transport. The 1.5 mm thick middle layer contains the cavities for vapor flow. To achieve hermetic seal, glass frit with four sealing rings, approximately 300 mu m wide and 30 mu m thick, is used to bond the edges and supporting posts. For experimental evaluations, 3 mm x 38 mm x 38 mm TGP vapor chambers are developed. The volume density of the heat transfer device is approximately 1.5 x 10(3) kg m(-3). Measurement of mass loss and stability studies of heat transfer indicates that the vapor chamber system is hermetically sealed. Using ethanol as the operating liquid, high heat transfer performance is demonstrated. Effective thermal conductivity reaches over 2500 W m(-1) . K-1. Under high g environment, experimental results show good liquid transport capabilities of the wick structures.