Fluid-to-Fluid Spot-to-Spreader (F2/S2) Hybrid Heat Sink for Integrated Chip-Level and Hot Spot-Level Thermal Management

2009 ◽  
Vol 131 (2) ◽  
Author(s):  
Craig Green ◽  
Andrei G. Fedorov ◽  
Yogendra K. Joshi
Keyword(s):  
Integrated Circuits ◽  
Heat Sink ◽  
Cooling System ◽  
Hot Spot ◽  
Heat Fluxes ◽  
Close Coupling ◽  
Thermal Fluids ◽  
Spot Cooling ◽  
Dynamics Simulations ◽  
Heat Sink Design

An innovative heat sink design aimed at meeting both the hot spot and large background heat flux requirements of next generation integrated circuits is presented. The heat sink design utilizes two separate unmixed fluids to meet the cooling requirements of the chip with one fluid acting as a fluidic spreader dedicated to cooling the hot spots only, while the second fluid serves as both a coolant for the background heat fluxes and an on-chip regenerator for the hot spot fluid. In this paper the conceptual heat sink design is presented and its theoretical capabilities are explored through optimization calculations and computational fluid dynamics simulations. It has been shown that through close coupling of the two thermal fluids the proposed hybrid heat sink can theoretically remove hot spot heat fluxes on the order of 1 kW/cm2 and background heat fluxes up to 100 W/cm2 in one compact and efficient package. Additionally, it has been shown that the F2/S2 design can handle these thermal loads with a relatively small pressure drop penalty, within the realm of existing micropump technologies. Finally, the feasibility of the F2/S2 design was demonstrated experimentally by modifying a commercially available, air-cooled aluminum heat sink to accommodate an integrated hot spot cooling system and fluidic spreader. The results of these experiments, where the prototype heat sink was able to remove hot spot heat fluxes of up to 365 W/cm2 and background heat fluxes of up to 20 W/cm2, are reported.

Adaptive Hot-Spot Cooling of Integrated Circuits Using Digital Microfluidics

2005 ◽  
Author(s):  
Phil Paik ◽  
Vamsee K. Pamula ◽  
Krishnendu Chakrabarty
Keyword(s):  
Integrated Circuits ◽  
Integrated Circuit ◽  
Hot Spots ◽  
High Performance ◽  
Cooling System ◽  
Hot Spot ◽  
Digital Microfluidics ◽  
Ic Design ◽  
Spot Cooling ◽  
Digital Microfluidic

Thermal management is becoming an increasingly important issue in integrated circuit (IC) design. The ability to cool ICs is quickly reaching a limit with today’s package-level solutions. While a number of novel cooling methods have been introduced, many of which are microfluidic approaches, these methods are unable to adaptively address the uneven thermal profiles and hot-spots generated in high performance ICs. In this paper, we present a droplet-based digital microfluidic cooling system for ICs that can adaptively cool hot-spots through real-time reprogrammable flow. This paper characterizes the effectiveness of microliter-sized droplets for cooling by determining the heat transfer coefficient of a droplet shuttling back and forth in an open system over a hot-spot at various speeds. Cooling is found to be significantly enhanced at higher flow rates of droplets. In order to further enhance cooling, the effect of varying droplet aspect ratio (width/height) in a confined system was also studied.

Study of the Hot Spots in Integrated Circuits Cooled by Microfluidic Heatsinks

2007 ◽  
Author(s):  
Alireza Motieifar ◽  
Cyrus Shafai ◽  
Hassan M. Soliman
Keyword(s):  
Fluid Flow ◽  
Integrated Circuits ◽  
Heat Sink ◽  
Hot Spots ◽  
Hot Spot ◽  
Solid Material ◽  
Heat Fluxes ◽  
Heat Sinks ◽  
Fem Method ◽  
Spot Temperature

The thermal input into high-power Integrated Circuits (IC) can have local peaks or hot spots with heat fluxes far exceeding 100 W/cm2. In this work, the temperature distribution on a microfluidic heatsink has been simulated using the FEM method. The effects of the fluid flow and thickness of the heatsink on the hot spot temperature have been studied. Simulations have been performed for a 1 cm × 1 cm heat sink loaded with 100 W/cm2 heating power, with a 1 mm hot spot of 1000 W/cm2 and a 3 mm hot spot of 500 W/cm2. Heat sinks fabricated from silicon, nickel, and copper are considered. These results show that the effect of increasing the thickness of the heatsink on the peak temperature of the hot spot depends on the solid material and the fluid flow. Simulations showed that the hot spot temperature rise can be about 40% higher if a nickel heat sink is used instead of a copper heat sink.

Investigation of On-Chip Hot Spot Cooling Using Microchannel Heat Sink

2013 ◽  
Vol 455 ◽  
pp. 466-469
Author(s):  
Yun Chuan Wu ◽  
Shang Long Xu ◽  
Chao Wang
Keyword(s):  
Heat Flux ◽  
Heat Sink ◽  
Hot Spots ◽  
Hot Spot ◽  
High Heat ◽  
High Heat Flux ◽  
Microchannel Heat Sink ◽  
Three Dimensional Model ◽  
Spot Cooling ◽  
On Chip

With the increase of performance demands, the nonuniformity of on-chip power dissipation becomes greater, causing localized high heat flux hot spots that can degrade the processor performance and reliability. In this paper, a three-dimensional model of the copper microchannel heat sink, with hot spot heating and background heating on the back, was developed and used for numerical simulation to predict the hot spot cooling performance. The hot spot is cooled by localized cross channels. The pressure drop, thermal resistance and effects of hot spot heat flux and fluid flow velocity on the cooling of on-chip hot spots, are investigated in detail.

Preliminary Analysis of Unprotected Loss of Heat Sink in Small Long Life Gas Cooled Fast Reactor

2015 ◽  
Vol 751 ◽  
pp. 268-272
Author(s):  
Su'ud Zaki ◽  
Nuri Trianti ◽  
Rosidah M. Indah
Keyword(s):  
Fast Reactor ◽  
Heat Sink ◽  
Channel Model ◽  
Cooling System ◽  
Hot Spot ◽  
Natural Circulation ◽  
Heat Removal ◽  
Reducing Power ◽  
Secondary System ◽  
Heat Removal System

The failure of the secondary side in Gas Cooled Fast Reactor system, which may contain co-generation system, will cause loss of heat sink (LOHS) accident. In this study accident analysis of unprotected loss of heat sink due to the failure of the secondary cooling system has been investigated. The thermal hydraulic model include transient hot spot channel model in the core, steam generator, and related systems. Natural circulation based heat removal system is important to ensure inherent safety capability during unprotected accidents. Therefore the system similar to RVACS (reactor vessel auxiliary cooling system) is also plays important role to limit the level of consequence during the accident. As the results some simulations for small 60 MWt gas cooled fast reactors has been performed and the results show that the reactor can anticipate the failure of the secondary system by reducing power through reactivity feedback and remove the rest of heat through natural circulations based decay heat removal (RVACS system).

Thermal Analysis of Miniature Low Profile Heat Sinks With and Without Fins

2009 ◽  
Vol 131 (3) ◽  
Author(s):  
V. Egan ◽  
P. A. Walsh ◽  
E. Walsh ◽  
R. Grimes
Keyword(s):  
Heat Transfer ◽  
Heat Sink ◽  
Volume Flow Rate ◽  
Electronic Devices ◽  
Heat Fluxes ◽  
Heat Sinks ◽  
Superior Performance ◽  
Low Profile ◽  
In Series ◽  
Heat Sink Design

Reliable and efficient cooling solutions for portable electronic devices are now at the forefront of research due to consumer demand for manufacturers to downscale existing technologies. To achieve this, the power consumed has to be dissipated over smaller areas resulting in elevated heat fluxes. With regard to cooling such devices, the most popular choice is to integrate a fan driven heat sink, which for portable electronic devices must have a low profile. This paper presents an experimental investigation into such low profile cooling solutions, which incorporate one of the smallest commercially available fans in series with two different heat sink designs. The first of these is the conventionally used finned heat sink design, which was specifically optimized and custom manufactured in the current study to complement the driving fan. While the second design proposed is a novel “finless” type heat sink suitable for use in low profile applications. Together the driving fan and heat sinks combined were constrained to have a total footprint area of 465 mm2 and a profile height of only 5 mm, making them ideal for use in portable electronics. The objective was to evaluate the performance of the proposed finless heat sink design against a conventional finned heat sink, and this was achieved by means of thermal resistance and overall heat transfer coefficient measurements. It was found that the proposed finless design proved to be the superior cooling solution when operating at low fan speeds, while at the maximum fan speed tested of 8000 rpm both provided similar performance. Particle image velocimetry measurements were used to detail the flow structures within each heat sink and highlighted methods, which could further optimize their performance. Also, these measurements along with corresponding global volume flow rate measurements were used to elucidate the enhanced heat transfer characteristics observed for the finless design. Overall, it is shown that the proposed finless type heat sink can provide superior performance compared with conventional finned designs when used in low profile applications. In addition a number of secondary benefits associated with such a design are highlighted including lower cost, lower mass, lower acoustics, and reduced fouling issues.

Thermoelectric Coolers for Hotspot Thermal Management of 3D Stacked Chips

2011 ◽  
Author(s):  
Matthew Redmond ◽  
Kavin Manickaraj ◽  
Owen Sullivan ◽  
Satish Kumar
Keyword(s):  
Integrated Circuits ◽  
Thermal Management ◽  
Power Density ◽  
Hot Spot ◽  
Thermal Contact ◽  
Three Dimensional ◽  
Heat Removal ◽  
Thermoelectric Coolers ◽  
Vertical Coupling ◽  
Spot Cooling

Three dimensional (3D) technologies with stacked chips have the potential to provide new chip architecture, improved device density, performance, efficiency, and bandwidth. Their increased power density also can become a daunting challenge for heat removal. Furthermore, power density can be highly non-uniform leading to time and space varying hotspots which can severely affect performance and reliability of the integrated circuits. Thus, it is important to mitigate thermal gradients on chip while considering the associated cooling costs. One method of thermal management currently under investigation is the use of superlattice thermoelectric coolers (TECs) which can be employed for on demand and localized cooling. In this paper, a detailed 3D thermal model of a stacked electronic package with two dies and four ultrathin integrated TECs is studied in order to investigate the efficacy of TECs in hot spot cooling for a 3D technology. We observe up to 14.6 °C of cooling at a hot spot inside the package by TECs. A strong vertical coupling has been observed between the TECs located in top and bottom dies. Bottom TECs can detrimentally heat the top hotspots in both steady state and transient operation. TECs need to be carefully placed inside the package to avoid such undesired heating. Thermal contact resistances between dies, inside the TEC module, and between the TEC and heat spreader are shown to have a crucial effect on TEC performance inside the package. We observed that square root current pulse can provide very efficient short-duration transient cooling at hotspots.

Design of a New Oil Spraying Device for Hot Spot Cooling in Large Scale Electric Power Transformers

2008 ◽  
Vol 9 (2) ◽  
Author(s):  
Kourosh Mousavi Takami ◽  
Jafar Mahmoudi
Keyword(s):  
Thermal Management ◽  
Large Scale ◽  
Cooling System ◽  
Hot Spot ◽  
Considerable Effect ◽  
Power Transformers ◽  
Insulation Aging ◽  
Simulation Results ◽  
Spot Cooling ◽  
Spot Temperature

Hot spot temperature (HST) is the most important parameter in the operation of power transformers. The HST has to be held under a prescribed limit. HST has a considerable effect on the insulation aging. Therefore detecting, monitoring and removing the HST could be a very important and necessary action for utilities. A new design of oil spraying and its effect, along with a thermal management in a transformer cooling system has been studied in this paper. The effect of oil fluid flow on the HST problem has been considered in this paper; and the calculations and simulation have been performed by Ants algorithm. The simulation results have been validated based on a 230/63/20 kV, 250MVA transformer at the Sari substation in Iran, and the results indicate that the new design could mitigate the limitations of transformer loading due to the HST problem. The Ants algorithm have been proposed and applied for accomplishing this task and to give an improved level of accuracy.

Enhanced Thermoelectric Cooler for On-Chip Hot Spot Cooling

2007 ◽  
Author(s):  
Peng Wang ◽  
Avram Bar-Cohen ◽  
Bao Yang
Keyword(s):  
Hot Spot ◽  
Heat Fluxes ◽  
Operating Conditions ◽  
Optimum Operating ◽  
Cooling Power ◽  
Thermoelectric Cooler ◽  
Thermoelectric Coolers ◽  
Cooling Performance ◽  
Spot Cooling ◽  
On Chip

Due to shrinking feature size and increasing transistor density, combined with the performance demanded from next-generation microprocessors, on-chip hot spots, with their associated high heat fluxes and sharp temperature gradients, have emerged as the primary driver for thermal management of today’s IC technology. This paper describes the novel use of thermoelectric coolers for on-chip hot spot cooling through the use of a copper mini-contact pad, which connects the thermoelectric cooler and the silicon chip thus concentrating the thermoelectric cooling power. A package-level numerical simulation is developed to predict the local on-chip hot spot cooling performance which can be achieved with such mini-contacts. Attention is focused on the hot spot temperature reduction associated with variations in mini-contact size and the thermoelectric element thickness, as well as the parasitic effect of the thermal contact resistance introduced by the mini-contact enhanced TEC. This numerical model and simulation results are validated by comparison to spot cooling experiments with a uniformly heated chip serving as the test vehicle. The experimental results demonstrate that a copper mini-contact pad can improve spot cooling performance by 80 ∼ 115% on a 500μm thick silicon chip under optimum operating conditions and that larger power dissipation on the chip leads to better spot cooling performance.

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