Trapezoidal Microchannel Heat Sink With Pressure-Driven and Electro-Osmotic Flows for Microelectronic Cooling

Han, Yongdian; Lee, Yong Jiun; Zhang, Xiaowu

doi:10.1109/tcpmt.2013.2272478

Cited by 19 publications

(7 citation statements)

References 26 publications

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“…In electro-osmotic flow, the surface material that comes in contact with the electrolytic solution acquires a negative charge via deprotonation. The magnitude of the induced surface charge depends on the property of the surface and pH of the liquid and has been backed by many studies that showed that ionic strength has a significant influence on the zeta potential; hence, different zeta potentials correspond to different ionic strengths. ,, Due to the Coulombic force of attraction by the surface charge, there exists a non-uniform distribution of counter ions (having a charge opposite to the surface charge), and this distribution is referred to as the electric double layer (EDL). The initial layer of EDL is known as the stern layer, and the second layer is known as the diffuse layer.…”

Section: Problem Description and Numerical Methodologymentioning

confidence: 99%

“…Here, ϵ and ϵ o represents the relative permittivity and permittivity of vacuum respectively. The temperature dependence of relative permittivity is calculated using ϵ( T ) = 305.7 × exp ( – T /219) as referred in ref . The PDE for ion distribution is solved in COMSOL…”

Section: Problem Description and Numerical Methodologymentioning

confidence: 99%

“…They found the pressuredriven flow to be greatly enhanced by the addition of electroosmosis. Han et al 28 conducted a numerical study of flow and heat transfer in a 3D microchannel of trapezoidal shape considering the effects of both the pressure gradient and electro-osmosis. They assumed the Helmholtz−Smoluchowski velocity as a slip boundary condition on the walls and found that both flow and heat transfer are increased by the use of electro-osmosis.…”

Section: Introductionmentioning

confidence: 99%

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Electro-osmosis Aided Thin-Film Evaporation from a Micropillar Wick Structure

2022

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The heat-dissipating capacity of a surface having micropillar wick structures, which resembles the evaporator section of a vapor chamber, is mainly limited by the liquid flow rate through the porous structure (permeability) and the capillary pressure gradient. The efficacy of a regular vapor chamber is determined from two parameters, namely, the dry-out heat flux and temperature of the evaporator surface. These two parameters possess a counter relation to each other. The work described herein introduces and evaluates the performance of a novel idea of electroosmosis-aided thin-film evaporation from a micropillar array structure. This study is conducted using a discretized approach that is validated against the thin-film evaporation model and additionally the electroosmotic flow model with pre-existing pressure gradient conditions. The unique feature of this approach is that it results in an increment in the magnitude of dry-out heat flux without significantly changing the surface temperature, wherein the increase in permeability is due to the addition of electro-osmotic flow. This comprehensive model considers various geometries, zeta potentials, and extremal electric fields and establishes the beneficial effects of the application of an external electric field. The results are used to predict the sensitivity and the dependence of the dry-out heat flux and the evaporator surface temperature on these parameters. For a host of electro-osmotic parameters considered herein, a maximum increment of up to 320% in the dry-out heat flux is observed for an external electric field of 10 5 V/m. The study, therefore, conclusively demonstrates the beneficial impact of electro-osmosis in enhancing the dry-out heat flux without any significant Joule heating.

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Section: Problem Description and Numerical Methodologymentioning

confidence: 99%

Section: Problem Description and Numerical Methodologymentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Electro-osmosis Aided Thin-Film Evaporation from a Micropillar Wick Structure

2022

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“…Also, it is considered general knowledge, that elevated temperatures are adversely impacting reliability. As a consequence, an effective thermal management is essential for the GaN device is important to reach its full potential [5][6][7]. As has been shown previously, both micro-channel and micro-jet heat sinks can dissipate high heat fluxes anticipated in high power electronic devices [8][9][10].…”

Section: Background Informationmentioning

confidence: 99%

Optimizing Diamond Heat Spreaders for Thermal Management of Hotspots for GaN Devices

Obeloer

Bolliger

Han

et al. 2015

International Symposium on Microelectronics

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As devices become smaller while still requiring high reliability in the presence of extreme power densities, new thermal management solutions are needed. Nowhere is this more evident than with the use of Gallium Nitride (GaN) transistors, where engineers struggle with the thermal barriers limiting the ability to achieve the intrinsic performance potential of GaN semiconductor devices. Emerging as a common solution to this GaN thermal management challenge are metallized diamond heat spreaders. In this paper, a diamond heat spreader has been applied with a hybrid Si micro-cooler for to cool GaN devices. Several different grades and thicknesses of microwave CVD diamond heat spreaders, as well as various bonding layers, are characterized for their thermal effects. The heat spreader is bonded through a TCB (thermal compression bonding) process to a Si thermal test chip designed to mimic the hotspots of 8 GaN units. The heat dissipation capabilities were compared through experimental tests and fluid-solid coupling simulations, both showing consistent results. In one configuration, using a diamond heat spreader 400μm thick with a thermal conductivity > 2000W/mK, to dissipate 70W heating power, the maximum chip temperature can be reduced by 40.4%, for test chips 100μm thick. And 10kW/cm2 hotspot heat flux can be dissipated while maintaining the maximum hotspot temperature under 160ºC. The concentrated heat flux has been effectively reduced by the diamond heat spreader, and much better cooling capability of the Si micro-cooler has been achieved for high power GaN devices.

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“…This cross section is rather typical and obtained by wet etching the microchannel on a silicon wafer of h100i orientation. Trapezoidal cross sections are important because it is observed that the thermal performance of a micro-heat sink with trapezoidal cross section is better than its rectangular counterpart [18,19]. Furthermore, the data available in the literature largely fall in the slip flow regime (0.001 \ Kn m-\ 0.1) and the data in the transition regime (0.1 \ Kn m \ 10) is rather sparse.…”

Section: Introductionmentioning

confidence: 99%

Determination of tangential momentum accommodation coefficient and slip coefficients for rarefied gas flow in a microchannel

2018

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This paper presents an experimental study of rarefied gas flow in a trapezoidal microchannel with a constant depth of 103 lm, top width of 1143 lm, bottom width of 998 lm and length of 2 cm. The aim of the study is to verify the upper limit of the validity of the second-order slip boundary condition to model rarefied gas flows. The slip coefficients and the tangential momentum accommodation coefficient (TMAC) are determined for three different gases, viz. argon, nitrogen and oxygen, and it is observed that they compare well to the literature values. The range of mean Knudsen number (Kn m) investigated is 0.007-1.2. The non-dimensional mass flow rate exhibits the well-known Knudsen minimum in the transition regime (Kn m * 1). It is seen that the Navier-Stokes equation with a second-order boundary condition fits the data satisfactorily with a high value of correlation coefficient (r 2 [ 99.95%) in the entire range of Kn m investigated. This work contributes by extending the range of Knudsen number studied in the context of validity of the second-order slip boundary condition.

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Trapezoidal Microchannel Heat Sink With Pressure-Driven and Electro-Osmotic Flows for Microelectronic Cooling

Cited by 19 publications

References 26 publications

Electro-osmosis Aided Thin-Film Evaporation from a Micropillar Wick Structure

Electro-osmosis Aided Thin-Film Evaporation from a Micropillar Wick Structure

Optimizing Diamond Heat Spreaders for Thermal Management of Hotspots for GaN Devices

Determination of tangential momentum accommodation coefficient and slip coefficients for rarefied gas flow in a microchannel

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