3D IC With Embedded Microfluidic Cooling: Technology, Thermal Performance, and Electrical Implications

2015 ◽  
Author(s):  
Xuchen Zhang ◽  
Xuefei Han ◽  
Thomas E. Sarvey ◽  
Craig E. Green ◽  
Peter A. Kottke ◽  
...  
Keyword(s):  
Heat Sink ◽  
Single Phase ◽  
Electrical Performance ◽  
Thermal Testing ◽  
Two Phase ◽  
Cooling Technology ◽  
Silicon Vias ◽  
The Impact ◽  
Measured Pressure ◽  
The Heat Transfer Coefficient

In this paper, a novel thermal testbed with an embedded micropin-fin heat sink is designed and fabricated. The micropin-fin array has a nominal height of 200 μm and a diameter of 90 μm. Single phase and two phase thermal testing of the micropin-fin array heat sink are performed using deionized (D.I.) water as the coolant below atmospheric pressure. The measured pressure drop is as high as 100 kPa with a mass flux of 1637 kg/m2s at a heat flux of 400 W/cm2 in a two-phase regime. The heat transfer coefficient and the vapor quality are calculated and reported. The impact of microfluidic cooling on the electrical performance of the 3D interconnects is also analyzed. The high aspect ratio through silicon vias (TSVs) used in the electrical analysis have a nominal diameter of 10 μm.

Two-Phase Flow in Microchannels

2001 ◽  
Author(s):  
G. Hetsroni ◽  
A. Mosyak ◽  
Z. Segal
Keyword(s):  
Heat Sink ◽  
High Speed ◽  
Single Phase ◽  
Flow Boiling ◽  
Electronics Cooling ◽  
Working Fluid ◽  
Microchannel Heat Sink ◽  
Two Phase ◽  
Infrared Radiometry ◽  
Phase Water

Abstract Experimental investigation of a heat sink for electronics cooling is performed. The objective is to keep the operating temperature at a relatively low level of about 323–333K, while reducing the undesired temperature variation in both the streamwise and transverse directions. The experimental study is based on systematic temperature, flow and pressure measurements, infrared radiometry and high-speed digital video imaging. The heat sink has parallel triangular microchannels with a base of 250μm. According to the objectives of the present study, Vertrel XF is chosen as the working fluid. Experiments on flow boiling of Vertrel XF in the microchannel heat sink are performed to study the effect of mass velocity and vapor quality on the heat transfer, as well as to compare the two-phase results to a single-phase water flow.

CFD Analysis of Thermal Shadowing and Optimization of Heatsinks in 3rd Generation Open Compute Server for Single-Phase Immersion Cooling

2019 ◽  
Author(s):  
Jimil M. Shah ◽  
Ravya Dandamudi ◽  
Chinmay Bhatt ◽  
Pranavi Rachamreddy ◽  
Pratik Bansode ◽  
...  
Keyword(s):  
Thermal Management ◽  
Power Density ◽  
Heat Sink ◽  
Single Phase ◽  
Data Centers ◽  
Air Cooling ◽  
Third Generation ◽  
Dielectric Fluids ◽  
Immersion Cooling ◽  
The Impact

Abstract In today’s networking world, utilization of servers and data centers has been increasing significantly. Increasing demand of processing and storage of data causes a corresponding increase in power density of servers. The data center energy efficiency largely depends on thermal management of servers. Currently, air cooling is the most widely used thermal management technology in data centers. However, air cooling has started to reach its limits due to high-powered processors. To overcome these limitations of air cooling in data centers, liquid immersion cooling methods using different dielectric fluids can be a viable option. Thermal shadowing is an effect in which temperature of a cooling medium increases by carrying heat from one source and results in decreasing its heat carrying capacity due to reduction in the temperature difference between the maximum junction temperature of successive heat sink and incoming fluid. Thermal Shadowing is a challenge for both air and low velocity oil flow cooling. In this study, the impact of thermal shadowing in a third-generation open compute server using different dielectric fluids is compared. The heat sink is a critical part for cooling effectiveness at server level. This work also provides an efficient range of heat sinks with computational modelling of third generation open compute server. Optimization of heat sink can allow to cool high-power density servers effectively for single-phase immersion cooling applications. A parametric study is conducted, and significant savings in the volume of a heat sink have been reported.

Filter-Based Unsteady RANS Computations for Single-Phase and Cavitating Flows

Volume 3 ◽  
2004 ◽  
Author(s):  
Jiongyang Wu ◽  
Wei Shyy ◽  
Stein T. Johansen
Keyword(s):  
Eddy Viscosity ◽  
Single Phase ◽  
Experimental Information ◽  
Time Dependent ◽  
Navier Stokes ◽  
Cavitating Flows ◽  
Two Phase ◽  
Navier Stokes Equation ◽  
Filter Size ◽  
The Impact

The widely used Reynolds-Averaged Navier-Stokes (RANS) approach, such as the k-ε two-equation model, has been found to over-predict the eddy viscosity and can dampen out the time dependent fluid dynamics in both single- and two-phase flows. To improve the predictive capability of this type of engineering turbulence closures, a consistent method is offered to bridge the gap between DNS, LES and RANS models. Based on the filter size, conditional averaging is adopted for the Navier-Stokes equation to introduce one more parameter into the definition of the eddy viscosity. Both time-dependent single-phase and cavitating flows are simulated by a pressure-based method and finite volume approach in the framework of the Favre-averaged equations coupled with the new turbulence model. The impact of the filter-based concept, including the filter size and grid dependencies, is investigated using the standard k-ε model and with the available experimental information.

VLSI Hotspot Cooling Using Two-Phase Microchannel Convection

2002 ◽  
Author(s):  
Jae-Mo Koo ◽  
Sungjun Im ◽  
Eun Seok Cho ◽  
Ravi S. Prasher ◽  
Evelyn Wang ◽  
...  
Keyword(s):  
Boundary Conditions ◽  
Heat Sink ◽  
Junction Temperature ◽  
Microchannel Heat Sink ◽  
Signal Delay ◽  
Two Phase ◽  
Silicon Chips ◽  
Vlsi Chip ◽  
Spatially Varying ◽  
The Impact

Two-phase microchannel heat sinks are promising for the cooling of high power VLSI chips, in part because they can alleviate spatial temperature variations, or hotspots. Hotspots increase the maximum junction temperature for a given total chip power, thereby degrading electromigration reliability of interconnects and inducing strong variations in the signal delay on the chip. This work develops a modeling approach to determine the impact of conduction and convection on hotspot cooling for a VLSI chip attached to a microchannel heat sink. The calculation approach solves the steady-state two-dimensional heat conduction equations with boundary conditions of spatially varying heat transfer coefficient and water temperature profile. These boundary conditions are obtained from a one-dimensional homogeneous two-phase model developed in previous work, which has been experimentally verified through temperature distribution and total pressure drop measurements. The new simulation explores the effect of microchannels on hotspot alleviation for 20 mm × 20 mm silicon chips subjected to spatially varying heat generation totaling 150 W. The results indicate that a microchannel heat sink of thickness near 500 μm can yield far better temperature uniformity than a copper spreader of thickness 1.5 mm.

Modeling and Simulation Challenges in Embedded Two Phase Cooling: DARPA’s ICECool Program

2015 ◽  
Author(s):  
Kaiser Matin ◽  
Avram Bar-Cohen ◽  
Joseph J. Maurer
Keyword(s):  
Heat Transfer ◽  
Modeling And Simulation ◽  
Coefficient Of Thermal Expansion ◽  
Operating Conditions ◽  
Electrical Performance ◽  
Two Phase ◽  
Modeling Tools ◽  
Analysis And Design ◽  
System Pressure ◽  
The Impact

Modeling and simulation of two-phase phenomena, as well as their impact on electrical performance and physical integrity are critical to the success of embedded cooling strategies. In DARPA’s Intrachip/Interchip Embedded Cooling (ICECool) program, thermal/electrical/mechanical co-simulation and modeling tools are being applied to the analysis and design of RF GaN MMIC (Monolithic Microwave Integrated Circuit) Power Amplifiers (PA) and digital ICs, with the ultimate goal of achieving greater than 3X electronic performance improvement. This paper addresses various simulation strategies and numerical techniques adopted by the DARPA ICECool performers, with attention devoted to co-simulation through coupled iterations of thermal, mechanical and electrical behavior for capturing device characteristics and predicting reliability and “best in class” simulations that can provide an understanding of device behavior during rugged operating conditions impacted by multi-physics environments. The effect of CTE (Coefficient of Thermal Expansion) mismatch on bond and structural integrity, the impact of cooling fluid choice on performance, the factors affecting erosion/corrosion in the microchannels, as well as electro-migration limits and joule heating effects, will also be addressed. A separate discussion of various two-phase issues, including interface tracking, system pressure drops, conjugate heat transfer, estimating near wall heat transfer coefficients, and predicting CHF (Critical Heat Flux) and dryout is also provided.

scholarly journals Analysis of welding kind impact upon phase structure and inner stresses of austenitic and duplex steel welded joints

2020 ◽  
Vol 2020 (3) ◽  
pp. 3-11
Author(s):  
Sergey Kuryntsev
Keyword(s):  
Thermal Treatment ◽  
Welded Joints ◽  
Phase Structure ◽  
High Performance ◽  
Single Phase ◽  
Negative Impact ◽  
Two Phase ◽  
Duplex Steel ◽  
High Cooling Rates ◽  
The Impact

A literature review and own investigations of the impact of a welding kind and post-welding thermal treatment upon a phase structure and residual stresses of welded joints are carried out. It is defined that such high-performance and promising welding kinds as electronic-beam welding (EBW) and laser welding (LW) have a negative impact upon a phase structure of two-phase (duplex) and single-phase steels as a result of high cooling rates of welded joints.

Computational Modeling of Extreme Heat Flux Microcooler for GaN-Based HEMT

2015 ◽  
Author(s):  
Hyoungsoon Lee ◽  
Yoonjin Won ◽  
Farzad Houshmand ◽  
Catherine Gorle ◽  
Mehdi Asheghi ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Single Phase ◽  
Simulation Models ◽  
Transfer Coefficients ◽  
Two Phase ◽  
Ansys Fluent ◽  
Heat Transfer Coefficients ◽  
Gan Hemt ◽  
Simulation Results ◽  
The Impact

This study explores an extreme heat flux limit of microcooler for GaN-based HEMTs (high electron mobile transistors) which have local power densities exceeding 30 kW/cm2 using both solid conduction simulation and single-phase/two-phase conjugate simulations. Solid conduction simulation models are developed for full geometry of the microcooler to account for the overall thermal resistances from GaN HEMT to working fluid. This allows investigating the temperature distribution of the suggested microcooler. Parametric studies are also performed to investigate the impact of geometries and heat transfer coefficients on the junction temperature. The solid conduction simulation results using COMSOL Multiphysics agree well with single-cell ANSYS Fluent simulation results. Separately, fluid-solid conjugate CFD (Computational Fluid Dynamics) simulation models provide the detailed flow information in the microchannel using a single-channel geometry with symmetry boundary conditions. Single-phase CFD simulations obtain the lower bound of total pressure drop and heat transfer coefficient at the microchannel walls for a mass velocity range of G = 6000–24000 kg/m2-s. The local temperatures and velocity distributions are reported that can help with identifying the locations of the maximum velocity and recirculation regions that are susceptible to dryouts. Two additional alternative tapered inlet designs are proposed to alleviate the significant pressure loss at the entrance of the SiC channel. The impact of the tapered inlet designs on pressure drops and heat transfer coefficients is also investigated. Two-phase simulations in microchannel are conducted using Volume-of-Fluid (VOF) method embedded in ANSYS Fluent to investigate two-phase flow patterns, flow boiling, and temperature distributions within the GaN HEMT device and SiC etched mircochannels. A user-defined function (UDF) accounts for the phase change process due to boiling at the microchannel walls. The results show that the time relaxation factor, ri has a strongly influence on both numerical convergence and flow solutions.

Three-Dimensional Integrated Circuit With Embedded Microfluidic Cooling: Technology, Thermal Performance, and Electrical Implications

2016 ◽  
Vol 138 (1) ◽  
Author(s):  
Xuchen Zhang ◽  
Xuefei Han ◽  
Thomas E. Sarvey ◽  
Craig E. Green ◽  
Peter A. Kottke ◽  
...  
Keyword(s):  
Thermal Performance ◽  
Integrated Circuit ◽  
Single Phase ◽  
Three Dimensional ◽  
Phase Region ◽  
Heat Sinks ◽  
Thermal Testing ◽  
Two Phase ◽  
Maximum Heat ◽  
Maximum Heat Transfer

This paper reports on novel thermal testbeds with embedded micropin-fin heat sinks that were designed and microfabricated in silicon. Two micropin-fin arrays were presented, each with a nominal pin height of 200 μm and pin diameters of 90 μm and 30 μm. Single-phase and two-phase thermal testing of the micropin-fin array heat sinks were performed using de-ionized (DI) water as the coolant. The tested mass flow rate was 0.001 kg/s, and heat flux ranged from 30 W/cm2 to 470 W/cm2. The maximum heat transfer coefficient reached was 60 kW/m2 K. The results obtained from the two testbeds were compared and analyzed, showing that density of the micropin-fins has a significant impact on thermal performance. The convective thermal resistance in the single-phase region was calculated and fitted to an empirical model. The model was then used to explore the tradeoff between the electrical and thermal performance in heat sink design.

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