Fabrication and experimental investigation of silicon micro heat pipes for cooling electronics

Abstract

An experimental investigation was conducted to determine the thermal behaviour of micro heat pipe (MHP) arrays micromachined in silicon wafers. Two types of MHP arrays were tested, one with triangular channels, 230 μm wide, 170 μm deep, and the other with triangular channels, 500 μm wide, 340 μm deep, coupled with arteries. Both types of arrays were fabricated using an anisotropic etching process. Once fabricated, a plain Si wafer was used to seal the pipe array hermetically. Two working fluids were tested, ethanol and methanol. A polysilicon heater was used to supply the heat input, and cooling water flowing through the condenser was used as a heat sink. Fill charges from 0% up to 66% were tested. The axial temperature variation along the length of the pipe was measured using T-type thermocouples connected to a data acquisition system. The effective thermal conductivity was evaluated using the experimental temperature profiles and 3D thermal modelling. The results show a maximum improvement of 300% in effective thermal conductivity at high heat flux, which demonstrates enhanced heat transfer in a prototype with liquid arteries.

Recent Advances in Vapor Chamber Transport Characterization for High-Heat-Flux Applications

“…Silicon micro heat pipes generally are described by an embedded array of discrete parallel non-circular channels that each behave as a two-phase evaporation/condensation loop to increase the inherent thermal conductivity of silicon [183][184][185]. Several investigations have also developed planar vapor chambers composed entirely of silicon with axially-grooved wick structures [186].…”

A New Reference Correlation for the Viscosity of Methanol

“…22 In fact, the future hydrogen economy may largely rely on methanol because it is safer to distribute hydrogen chemically bonded in liquid form than as a pure compound through gas pipelines. Some other applications of methanol include heat pipes in solar energy applications, 68 working fluid in cooling microelectronics, 79 and as an inhibitor of the formation of gas hydrates in pipelines. 69 The development of accurate thermophysical property formulations for methanol will aid engineers involved in process design in these and other fields.…”

Lamination and Characterization of a Polyethylene-Terephthalate Flexible Micro Heat Pipe

“…Many reports focused on micro heat pipe fabrication using silicon wafer for patterning hundred-micrometer structures (Berre et al, 2003). Although such materials could against high pressure difference, they have low or even no flexibility and are expensive (Sobhan et al, 2007).…”