Electro-Thermal Co-Design of Emerging Electronics

Transcription

1 Electro-Thermal Co-Design of Emerging Electronics with on-chip integration of novel cooling strategies Suresh V. Garimella Cooling Technologies Research Center, an NSF I/UCRC Purdue University 1

2 Grand Challenge Continued scaling of electronics is being impeded, since: High-performance VLSI is approaching the passive cooling limit Current design approaches require large margins, leading to poor power efficiency Low-power applications require further significant reductions in power per function Electrical and thermal designs and hardware typically interface only at the chip level There is a critical need for thermal solutions that are matched with electrical needs at matched spatial and temporal granularity 2

3 Some Solutions Relative Temperature (C) Microjets 50μm Novel interface materials Thermoelectrics Laser cooling Microchannels Piezofans Integrated Thermal Management and Control Ions Neutral Molecules Micropumps Microscale thinfilm evaporation Ionic winds Electric Field and Ion Motion Pumping Electrodes Substrate Electrowetting

4 Research Needs Interfaces (improved contact conductance/spreading) models, materials, characterization Novel high-conductivity materials Embedded thermoelectrics Passive liquid-based approaches Integrated, active microfluidic approaches (microchannels, micropumps, electrowetting, microjets) Development of new fluids Improved ultimate heat rejection novel approaches to air cooling (ion driven flows, low-noise mini-fans, piezoelectric fans) Power reduction for all active cooling strategies Energy recovery Improved micro- and nano-scale diagnostics

5 Thermal Contact Conductance Black, Garimella, AIAA JTHT, 2005 Singhal, Litke, Black, Garimella, IJHMT, 2005 Xu, Fisher, IJHMT, 2006 Load Cell Experiment (Al 1 micron) Numerical Prediction Before Numerical Prediction After Column Support Bolts Column Support Bolts TCC (W/K) Direction of onedimensional heat flux Insulated heat source Electrolytic iron flux meters Al-Al 1 μm Ra Interface Pressure (MPa) H c Radiation shield (Front half removed to expose test column) Experimental samples H s H equ Column Power Input Terminals Insulated heat sink iv Coolant Inlet Coolant Outlet Base Plate Experimental Test Column Coated Joints T Fisher CNT TIM

6 Heat Pipes and Vapor Chambers Transient analysis of miniature flat heat pipes at high heat fluxes Prediction of transient temperature, velocity and pressure fields in the heat pipe Prediction of dryout Dissipation from multiple hot spots Prediction of required wick properties Wick performance and transport measurements Thermocouple Pass-through Heater Conical Cap Condensate Collection Annulus Vacuum Pressure Gage Clamp Wick Liquid Pool Pressure drop (N/m 2 ) z(m) condenser section mm x(m) 400 Δ P v Vapor pressure drop Vapor core thickness = 0.4 mm Vapor core thickness = 0.8 mm Vadakkan, Garimella, Murthy, JHT, 2004 Iverson et al., AIAA JTHT, Δ P l liquid pressure drop x(m)

7 Thin-Film Evaporation Delineate contributions of heat transfer, thermocapillary convection and evaporation in the thin film region to the overall heat transfer from liquid films Develop methods of sustaining thin films over larger areas Develop integrated modeling tools which account for heat transfer within the film, vapor diffusion and evaporation Contact line Tube Wall Meniscus Dhavaleswarapu et al., Phys Fluids 2007 Wang, Garimella, Murthy, IJHMT 2007 Tube Wall MicroPIV in evaporating meniscus

8 Two-Phase Transport in Microchannels Fundamentals of convective boiling and two-phase flow in microscale channels still not well understood In-situ measurement of temperature, pressure Instabilities and hysteresis effects Flow-regime determination and regime-based modeling ONB studies Models for two-phase pressure drop and heat transfer coefficients Liu, Lee, Garimella, IJHMT, 2005 Liu, Garimella, JHT, (In press) Lee, Garimella, IJHMT (in press)

9 Two-Phase Transport in Microchannels Fluid outlet Inlet and outlet Temperatures W c = 381 μm, H c = 392 μm Q = 35 ml/min 12,500 fps Heat sink Liquid inlet Interface for wall temperature measurement and heat input Pressure drop q = 6.77 W/cm Chen, Garimella, IJ Multiphase Flow 2006 Chen, Garimella, ASME JEP 2006 Re = 230 (liquid at inlet)

10 Chip-Integrated Micropumps Chip-integration of microscale pumping can increase heat removal with small form factors, significantly reducing package resistance Need for: Low-cost, reliable MEMS components Low-volume integrated micropumps Considerations: Flow rate Maximum back pressure Miniaturization Suitability for integration Enhance induction EHD with fluid motion from a vibrating diaphragm -V/2 Increasing Electrical Conductivity Diaphragm with Electrodes Channel Substrate Traveling-wave sinusoid -V -V/2 Piezoelectric Patch Heat Flux + V/2 Charge Clouds + V + V/2 Fluid Velocity Heat Flux (Active Device) Combined Stack Bus bars and electrodes Microfabricated channels Singhal, Garimella, IEEE TAP 2005 Singhal, Garimella, Raman, Appl Mech Rev 2004

11 Electrically Actuated Droplets Develop technologies enabling electrical actuation and control of droplets for providing chip-integrated thermal management solutions Significantly enhanced control of flow at the microscale High liquid velocities at low voltages Noiseless, very low power consumption Solutions for chip-level and hot-spot thermal management Droplet Droplet Droplet resting on top of grooves Droplet wetting grooves Bahadur, Garimella, Langmuir 2007 Bahadur, Garimella, JMM 2006 Patent pending

12 Microscale Ion Driven Airflow Chip-integrated, ionic wind convection enhancement Increases heat transfer over local, high-heat-flux regions Provides additional cooling capacity without impacting volume of overall cooling system Provides flexibility in thermal solutions for portable electronics boundary layer profile upstream of ionic wind boundary layer profile downstream of ionic wind 30 C C C C ionized air e ~10μm φ emitting cathode Infrared image of a heated plate with bulk flow cooling Demonstration of 25 C drop due to ionic wind Schlitz, Garimella, Fisher, ASME IMECE, 2004 Zhang, Fisher, Garimella, J Appl Phys, 2004 Peterson, Zhang, Fisher, Garimella, PSST, 2005 Go, Garimella, Fisher, Mongia, J Appl Phys (in press)

13 Miniature Piezoelectric Fans A y x B B B Piezoelectric Fan #1 A (a) t= 1/30 sec B D A (b) t= 2/30 sec (c) t= 3/30 sec A A (d) t= 5/30 sec Development of low-power, noiseless, piezoelectrially actuated vibrating cantilevers has added to the thermal management toolkit Continued development of predictive tools for design and optimization is needed P Piezoelectric Fan #2 Single-Fan Experiments G Flow visualization near a boundary, at different times; fan turned on at t = 0 s. Contours of local convection coefficients with A = 10 mm. G/A = 0.01 C A (e) t= 8/30 s (f) t= 10/30 (g) t= 13/30 s G/A = 0.50 G/A = 2.0 (h) t= 15/30 Two-Fan Experiments G/A = 0.01, P/A = 1.0 G/A = 0.01, P/A = 1.25 G/A = 0.01, P/A = 4.0 Kimber, Garimella, Raman, JHT (in press) Açıkalın, Garimella, Raman, Petroski, IJHFF (in press) Açıkalın, Wait, Garimella, Raman, HTE W/m2 K

14 Enhanced Transport in Open-Cell Foams Effective Thermal Conductivity, W/mK Alum inum - Air C alm idi E xperim ents Tetrakaidecahedron Model BCC Model Boomsma Model C alm idi M odel Bhattacharya M odel Porosity Porosity Analytical Fluent 2 R Radius R _ = Flow Direction Cube BCC Final Geometry y x Krishnan, Murthy, Garimella, ASME JHT, 2005 Krishnan, Murthy, Garimella, ASME JHT, 2006 z Constant Heat Flux

15 Selected References S. V. Garimella, Advances In Mesoscale Thermal Management Technologies for Microelectronics, Microelectronics Journal Vol. 37, pp , S. Krishnan, S. V. Garimella, G. Chrysler, and R. Mahajan, Towards a Thermal Moore s Law, IEEE Trans Advanced Packaging (in press). S. V. Garimella and C. B. Sobhan, Transport in Microchannels - A Critical Review, Ann. Rev. Heat Transfer, C. B. Sobhan and S. V. Garimella, A Comparative Analysis of Studies on Heat Transfer and Fluid Flow in Microchannels, Microscale Thermophysical Engineering, Vol. 5, pp , V. Singhal, S. V. Garimella, and A. Raman Microscale Pumping Technologies for Microchannel Cooling Systems, Applied Mechanics Reviews, Vol. 57, pp , S. V. Garimella, V. Singhal and D. Liu, On-Chip Thermal Management with Microchannel Heat Sinks and Integrated Micropumps, Procs IEEE Vol. 94, No. 8, pp , D. Liu, P.S. Lee, and S. V. Garimella, Prediction of the Onset of Nucleate Boiling in Microchannel Flow, International Journal of Heat and Mass Transfer, Vol. 48, pp , D. Liu, S. V. Garimella and S. T. Wereley, Infrared Micro-Particle Image Velocimetry Measurement in Silicon-Based Microdevices, Experiments in Fluids Vol. 38, pp , P.-S. Lee, S. V. Garimella, and D. Liu, Investigation of Heat Transfer in Rectangular Microchannels, International Journal of Heat and Mass Transfer, Vol. 48, pp , T. Chen and S. V. Garimella, Measurements and High-Speed Visualizations of Flow Boiling of a Dielectric Fluid in a Silicon Microchannel Heat Sink, Int J Multiphase Flow Vol. 32, pp , V. Singhal and S. V. Garimella, A Novel Valveless Micropump with Electrohydrodynamic Enhancement for High Heat Flux Cooling, IEEE Transactions on Advanced Packaging, Vol. 28, V. Singhal and S. V. Garimella, Induction Electrohydrodynamics Micropump for High Heat Flux Cooling, Sensors and Actuators A Vol. 134, pp , V. Bahadur and S. V. Garimella, Energy-Based Model for Electrowetting-Induced Droplet Actuation, Journal of Micromechanics and Microengineering Vol. 16, pp , V. Bahadur and S. V. Garimella, Electrowetting-Based Control of Static Droplet States on Rough Surfaces, Langmuir (available online). H. K. Dhavaleswarapu, P. Chamarthy, S. V. Garimella, and J. Y. Murthy, Experimental Investigation of Steady Buoyant- Thermocapillary Convection Near an Evaporating Meniscus, Physics of Fluids (in press). H. Wang, S. V. Garimella, and J. Y. Murthy, Characteristics of an Evaporating Thin Film in a Microchannel, International Journal of Heat and Mass Transfer (in press).

16 Selected References S. V. Garimella and C. B. Sobhan, Recent Advances in the Modeling and Applications of Nonconventional Heat Pipes, Chapter 4, Advances in Heat Transfer, Vol. 35, pp , U. Vadakkan, S. V. Garimella and J. Y. Murthy, Transport in Flat Heat Pipes at High Heat Fluxes from Multiple Discrete Heat Sources, ASME Journal of Heat Transfer, Vol. 126, pp , 2004 B. D. Iverson, T. W. Davis, S. V. Garimella, M. T. North, and S. Kang, Heat and Mass Transport in Heat Pipe Wick Structures, AIAA J Thermophysics and Heat Transfer Vol. 21, pp , V. Singhal, P. J. Litke, A. F. Black and S. V. Garimella, An Experimentally Validated Thermomechanical Model for the Prediction of Thermal Contact Conductance, International Journal of Heat and Mass Transfer Vol. 48, pp , A. F. Black, V. Singhal and S. V. Garimella, Analytical Investigation and Predictive Correlation for Constriction Resistance, AIAA J Thermophysics and Heat Transfer, Vol. 18, pp , D. J. Schlitz, S. V. Garimella and T. S. Fisher, Microscale Ion-Driven Air Flow over a Flat Plate, Procs. HT-FED04, ASME Heat Transfer/Fluids Engineering Summer Conference, HT-FED , July 11-15, 2004, Charlotte, NC. M. S. Peterson, W. Zhang, T. S. Fisher, and S. V. Garimella, Low-Voltage Ionization of Air with Carbon-Based Materials, Plasma Sources Science and Technology, Vol. 14, pp , W. Zhang, T. S. Fisher and S. V. Garimella, Simulation of Ion Generation and Breakdown in Atmospheric Air, Journal of Applied Physics, Vol 96, No. 11, pp , D. Go, S. V. Garimella, T. S. Fisher, and R. K. Mongia Ionic Winds for Locally Enhanced Cooling, Journal of Applied Physics (in press). T. Açıkalın, A. Raman and S. V. Garimella, Two-dimensional Streaming Flows Induced by Resonating Thin Beams, J Acoustical Society of America, Vol. 114, pp , S. Basak, A. Raman and S. V. Garimella, Dynamic Response Optimization of Piezoelectrically Excited Thin Resonant Beams, ASME Journal of Vibration and Acoustics Vol. 127, pp , M. Kimber, S. V. Garimella and A. Raman, Local Heat Transfer Coefficients Induced by Piezoelectrically Actuated Vibrating Cantilevers, ASME Journal of Heat Transfer (in press). S. Krishnan, J. Y. Murthy and S. V. Garimella, A Two-Temperature Model for Solid/Liquid Phase Change in Metal Foams, ASME Journal of Heat Transfer Vol. 127, pp , S. Krishnan, J. Y. Murthy and S. V. Garimella, A Two-Temperature Model for the Analysis of Passive Thermal Control Systems, ASME Journal of Heat Transfer, Vol. 126, pp , 2004.