P. Bansode, Rohit Suthar, Rabin Bhandari, A. Lakshminarayana, Naga Tejesh Ede, Gautam Gupta, V. Simon, Himanshu Modi, Vivek Nair, Pardeep Shahi, S. Saini, Krishna Bhavana Sivaraju, D. Agonafer
The data center's server power density and heat generation have increased exponentially because of the recent, unparalleled rise in the processing and storing of massive amounts of data on a regular basis. One-third of the overall energy used in conventional air-cooled data centers is directed toward cooling information technology equipment (ITE). The traditional air-cooled data centers must have low air supply temperatures and high air flow rates to support high-performance servers, rendering air cooling inefficient and compelling data center operators to use alternative cooling technology. Due to the direct interaction of dielectric fluids with all the components in the server, single-phase liquid immersion cooling (Sp-LIC) addresses mentioned problems by offering a significantly greater thermal mass and a high percentage of heat dissipation. Sp-LIC is a viable option for hyper-scale, edge, and modular data center applications because, unlike direct-to-chip liquid cooling, it does not call for a complex liquid distribution system configuration and the dielectric liquid can make direct contact with all server components. Immersion cooling is superior to conventional air-cooling technology in terms of thermal energy management however, there have been very few studies on the reliability of such cooling technology. A detailed assessment of the material compatibility of different electronic packaging materials for immersion cooling was required to comprehend their failure modes and reliability. For the mechanical design of electronics, the modulus, and glass transition temperature (Tg) are essential material characteristics. The substrate is a crucial element of an electronic package that has a significant impact on the reliability and failure mechanisms of electronics at both the package and the board level. As per Open Compute Project (OCP) design guidelines for immersion-cooled IT equipment, the traditional material compatibility tests from standards like ASTM 3455 can be used with certain appropriate adjustments. The primary focus of this research is to address two challenges: The first part is to understand the impact of thermal aging on the thermo-mechanical properties of the halogen-free substrate core in the single-phase immersion cooling. Another goal of the study is to comprehend how thermal aging affects the thermo-mechanical characteristics of the substrate core in the air. In this research the substrate core is aged in synthetic hydrocarbon fluid (EC110), Polyalphaolefin 6 (PAO 6), and ambient air for 720 hours each at two different temperatures: 85°C and 125°C and the complex modulus and the glass transition temperature before and after aging are calculated and compared.
{"title":"Impact of Immersion Cooling On Thermomechanical Properties of Halogen-free Substrate Core","authors":"P. Bansode, Rohit Suthar, Rabin Bhandari, A. Lakshminarayana, Naga Tejesh Ede, Gautam Gupta, V. Simon, Himanshu Modi, Vivek Nair, Pardeep Shahi, S. Saini, Krishna Bhavana Sivaraju, D. Agonafer","doi":"10.1115/1.4066044","DOIUrl":"https://doi.org/10.1115/1.4066044","url":null,"abstract":"\u0000 The data center's server power density and heat generation have increased exponentially because of the recent, unparalleled rise in the processing and storing of massive amounts of data on a regular basis. One-third of the overall energy used in conventional air-cooled data centers is directed toward cooling information technology equipment (ITE). The traditional air-cooled data centers must have low air supply temperatures and high air flow rates to support high-performance servers, rendering air cooling inefficient and compelling data center operators to use alternative cooling technology. Due to the direct interaction of dielectric fluids with all the components in the server, single-phase liquid immersion cooling (Sp-LIC) addresses mentioned problems by offering a significantly greater thermal mass and a high percentage of heat dissipation. Sp-LIC is a viable option for hyper-scale, edge, and modular data center applications because, unlike direct-to-chip liquid cooling, it does not call for a complex liquid distribution system configuration and the dielectric liquid can make direct contact with all server components. Immersion cooling is superior to conventional air-cooling technology in terms of thermal energy management however, there have been very few studies on the reliability of such cooling technology. A detailed assessment of the material compatibility of different electronic packaging materials for immersion cooling was required to comprehend their failure modes and reliability. For the mechanical design of electronics, the modulus, and glass transition temperature (Tg) are essential material characteristics. The substrate is a crucial element of an electronic package that has a significant impact on the reliability and failure mechanisms of electronics at both the package and the board level. As per Open Compute Project (OCP) design guidelines for immersion-cooled IT equipment, the traditional material compatibility tests from standards like ASTM 3455 can be used with certain appropriate adjustments. The primary focus of this research is to address two challenges: The first part is to understand the impact of thermal aging on the thermo-mechanical properties of the halogen-free substrate core in the single-phase immersion cooling. Another goal of the study is to comprehend how thermal aging affects the thermo-mechanical characteristics of the substrate core in the air. In this research the substrate core is aged in synthetic hydrocarbon fluid (EC110), Polyalphaolefin 6 (PAO 6), and ambient air for 720 hours each at two different temperatures: 85°C and 125°C and the complex modulus and the glass transition temperature before and after aging are calculated and compared.","PeriodicalId":15663,"journal":{"name":"Journal of Electronic Packaging","volume":null,"pages":null},"PeriodicalIF":2.2,"publicationDate":"2024-07-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141820079","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The demand for compact, lightweight, and stretchable printed electric circuits has increased with the advancement of flexible printing technology in electronics. The viability of environmentally friendly water-based inks with low-impact waste requires the development of process recipes for component attachment on flexible substrates. The focus of this paper is on demonstrating a comprehensive study of process parameters and component attachment on the aerosol jet printer (AJP) platform, utilizing water-based silver nanoparticle ink. The investigation covers printing parameters, including UAMFC, SMFC, stage speed, multiple passes, and sintering analysis (time and temperature). Evaluation of print quality is conducted using white light interferometry (WLI) and optical microscopy images. The cross-sectional area (CSA) of printed lines is computed by integrating the bell-shaped CSA obtained from the WLI test. Electrical and mechanical properties are quantified in terms of resistivity and shear load to failure. Optimized parameters from the printing and sintering process are employed to print traces, and various components are attached using Electrically Conductive Adhesive (ECA). The impact of sustainable ink and ECA on passive components is analyzed by comparing their performance before and after attachment. Components within an acceptable range of the rated value are in proper functioning order, contributing to the advancement of flexible and sustainable electronics. Finally, a practical differentiator circuit has been used to demonstrate the functionally working circuitry and compared the output with the simulated one.
{"title":"Process Recipe and Functional Circuitry Performance On Aerosol Jet Printed Water-Based Silver Ink","authors":"Pradeep Lall, Sabina Bimali, Scott Miller","doi":"10.1115/1.4066041","DOIUrl":"https://doi.org/10.1115/1.4066041","url":null,"abstract":"\u0000 The demand for compact, lightweight, and stretchable printed electric circuits has increased with the advancement of flexible printing technology in electronics. The viability of environmentally friendly water-based inks with low-impact waste requires the development of process recipes for component attachment on flexible substrates. The focus of this paper is on demonstrating a comprehensive study of process parameters and component attachment on the aerosol jet printer (AJP) platform, utilizing water-based silver nanoparticle ink. The investigation covers printing parameters, including UAMFC, SMFC, stage speed, multiple passes, and sintering analysis (time and temperature). Evaluation of print quality is conducted using white light interferometry (WLI) and optical microscopy images. The cross-sectional area (CSA) of printed lines is computed by integrating the bell-shaped CSA obtained from the WLI test. Electrical and mechanical properties are quantified in terms of resistivity and shear load to failure. Optimized parameters from the printing and sintering process are employed to print traces, and various components are attached using Electrically Conductive Adhesive (ECA). The impact of sustainable ink and ECA on passive components is analyzed by comparing their performance before and after attachment. Components within an acceptable range of the rated value are in proper functioning order, contributing to the advancement of flexible and sustainable electronics. Finally, a practical differentiator circuit has been used to demonstrate the functionally working circuitry and compared the output with the simulated one.","PeriodicalId":15663,"journal":{"name":"Journal of Electronic Packaging","volume":null,"pages":null},"PeriodicalIF":2.2,"publicationDate":"2024-07-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141819004","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Accelerated testing has been executed to examine the combined influence of electromigration (EM) stressors (elevated current density and elevated ambient temperature) and tensile stress on the lifetime of SAC305 solder joints (300 [µm] diameter) at two current densities (8,500 and 9,100 [A/cm^2]), two ambient temperatures (100 and 150 [°C]), and five tensile stresses (0, 0.5, 1, 2.5, and 5 [MPa]). 60 total samples were tested, four of which survived the 500-hour test duration limit. As tensile stress was increased, a significant reduction in lifetime was observed for each of the four EM conditions (current density-temperature pairs). Voltage drop across the solder samples was measured in situ, capturing the time to failure for all samples and allowing for the development of life prediction models based on the multi-stress experimental scenario. Post failure analysis of the samples tested under combined electromigration and tensile stress showed necking or breakage at the Cu/SAC305 interface on the upstream side of electron flux. Cross-sectional analysis of tested samples is consistent with findings from other studies regarding electromigration failure in Cu/SAC305/Cu solder joint assemblies, where the intermetallic regions at Cu/SAC305 interfaces grow asymmetrically. Inherent process-voids in the experimental samples are discussed as a source of error and a brief computational examination of the impact of process-related voiding on stress as well as current density and self-heating within solder samples is provided.
{"title":"Incorporating Tensile Stress into Electromigration Life Prediction for Cu/SAC305/Cu Solder Joints","authors":"Whit Vinson, David R. Huitink","doi":"10.1115/1.4066014","DOIUrl":"https://doi.org/10.1115/1.4066014","url":null,"abstract":"\u0000 Accelerated testing has been executed to examine the combined influence of electromigration (EM) stressors (elevated current density and elevated ambient temperature) and tensile stress on the lifetime of SAC305 solder joints (300 [µm] diameter) at two current densities (8,500 and 9,100 [A/cm^2]), two ambient temperatures (100 and 150 [°C]), and five tensile stresses (0, 0.5, 1, 2.5, and 5 [MPa]). 60 total samples were tested, four of which survived the 500-hour test duration limit. As tensile stress was increased, a significant reduction in lifetime was observed for each of the four EM conditions (current density-temperature pairs). Voltage drop across the solder samples was measured in situ, capturing the time to failure for all samples and allowing for the development of life prediction models based on the multi-stress experimental scenario. Post failure analysis of the samples tested under combined electromigration and tensile stress showed necking or breakage at the Cu/SAC305 interface on the upstream side of electron flux. Cross-sectional analysis of tested samples is consistent with findings from other studies regarding electromigration failure in Cu/SAC305/Cu solder joint assemblies, where the intermetallic regions at Cu/SAC305 interfaces grow asymmetrically. Inherent process-voids in the experimental samples are discussed as a source of error and a brief computational examination of the impact of process-related voiding on stress as well as current density and self-heating within solder samples is provided.","PeriodicalId":15663,"journal":{"name":"Journal of Electronic Packaging","volume":null,"pages":null},"PeriodicalIF":2.2,"publicationDate":"2024-07-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141819163","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Increasing heat flux in power electronics modules is taxing the limits of thermal management technologies. This is the result of wide bandgap semiconductor devices with superior voltage blocking capabilities. These same devices have the capability of operating at elevated junction temperatures when properly packaged. Transient liquid phase bonding forms intermetallic compounds with high melting temperatures at more conventional processing temperatures. Copper and tin transient liquid phase intermetallic formation in SAC305 solder bonds can be accelerated using copper nanowires. This work explores the feasibility of accelerated transient liquid phase bonding using solder and nanowires. This includes electroforming of nanowires, contact angle analysis of solder on nanowires, void analysis using scanning acoustic microscopy and cross-sectional scanning electron microscopy. SAC305 solder is deposited on substrates with 0.4 µm diameter copper nanowires using a 75µm stencil and subjected to solder reflow. It is found that atmospheric storage at 260 °C results in regions of complete intermetallic bonding after 2 hours. Shear strength of bonds completed with this nanowire transient liquid phase bonding method averages 11.99 kg or 13 MPa.
{"title":"Transient Liquid Phase Bond Acceleration Using Copper Nanowires","authors":"John Harris, David R. Huitink","doi":"10.1115/1.4066042","DOIUrl":"https://doi.org/10.1115/1.4066042","url":null,"abstract":"\u0000 Increasing heat flux in power electronics modules is taxing the limits of thermal management technologies. This is the result of wide bandgap semiconductor devices with superior voltage blocking capabilities. These same devices have the capability of operating at elevated junction temperatures when properly packaged. Transient liquid phase bonding forms intermetallic compounds with high melting temperatures at more conventional processing temperatures. Copper and tin transient liquid phase intermetallic formation in SAC305 solder bonds can be accelerated using copper nanowires. This work explores the feasibility of accelerated transient liquid phase bonding using solder and nanowires. This includes electroforming of nanowires, contact angle analysis of solder on nanowires, void analysis using scanning acoustic microscopy and cross-sectional scanning electron microscopy. SAC305 solder is deposited on substrates with 0.4 µm diameter copper nanowires using a 75µm stencil and subjected to solder reflow. It is found that atmospheric storage at 260 °C results in regions of complete intermetallic bonding after 2 hours. Shear strength of bonds completed with this nanowire transient liquid phase bonding method averages 11.99 kg or 13 MPa.","PeriodicalId":15663,"journal":{"name":"Journal of Electronic Packaging","volume":null,"pages":null},"PeriodicalIF":2.2,"publicationDate":"2024-07-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141819822","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Jacob Lamotte-Dawaghreh, Joseph Herring, S. Pundla, Rohit Suthar, Vivek Nair, P. Bansode, Gautam Gupta, D. Agonafer, Joseph Madril, Tim Ouradnik, Michael Matthews, Ian Winfield
To fulfill the increasing data processing demands within modern data centers, a corresponding increase in server performance is necessary. This leads to subsequent increases in power consumption and heat generation in the servers due to high performance processing units. Currently, air cooling is the most widely used thermal management technique in data centers, but it has started to reach its limitations in cooling of high-power density packaging. Therefore, industries utilizing data centers are looking to single-phase immersion cooling to reduce the operational and cooling costs by enhancing the thermal management of servers. In this study, heat sinks with triply periodic minimal surface lattice structures were designed for application in single-phase immersion cooling of data center servers. These designs are made possible by Electrochemical Additive Manufacturing technology due to their complex topologies. The Electrochemical Additive Manufacturing process allows for generation of complex heat sink geometries not possible using traditional manufacturing processes. Geometric complexities including amorphous and porous structures with high surface area to volume ratio enable Electrochemical Additive Manufacturing heat sinks to have superior heat transfer properties. Our objective is to compare various heat sink geometries by minimizing max case temperature in a single-phase immersion cooling setup for a natural convection setup. Computational fluid dynamics in ANSYS Fluent is utilized to compare the Electrochemical Additive Manufacturing heat sink designs. The additively manufactured heat sink designs are evaluated by comparing their thermal performance under natural convection conditions. This study presents a novel approach to heat sink design and bolsters the capability of Electrochemical Additive Manufacturing-produced heat sinks.
{"title":"Electrochemical Additive Manufacturing Based Design of a Heat Sink for Single Phase Natural Convection Immersion Cooling Application","authors":"Jacob Lamotte-Dawaghreh, Joseph Herring, S. Pundla, Rohit Suthar, Vivek Nair, P. Bansode, Gautam Gupta, D. Agonafer, Joseph Madril, Tim Ouradnik, Michael Matthews, Ian Winfield","doi":"10.1115/1.4065987","DOIUrl":"https://doi.org/10.1115/1.4065987","url":null,"abstract":"\u0000 To fulfill the increasing data processing demands within modern data centers, a corresponding increase in server performance is necessary. This leads to subsequent increases in power consumption and heat generation in the servers due to high performance processing units. Currently, air cooling is the most widely used thermal management technique in data centers, but it has started to reach its limitations in cooling of high-power density packaging. Therefore, industries utilizing data centers are looking to single-phase immersion cooling to reduce the operational and cooling costs by enhancing the thermal management of servers. In this study, heat sinks with triply periodic minimal surface lattice structures were designed for application in single-phase immersion cooling of data center servers. These designs are made possible by Electrochemical Additive Manufacturing technology due to their complex topologies. The Electrochemical Additive Manufacturing process allows for generation of complex heat sink geometries not possible using traditional manufacturing processes. Geometric complexities including amorphous and porous structures with high surface area to volume ratio enable Electrochemical Additive Manufacturing heat sinks to have superior heat transfer properties. Our objective is to compare various heat sink geometries by minimizing max case temperature in a single-phase immersion cooling setup for a natural convection setup. Computational fluid dynamics in ANSYS Fluent is utilized to compare the Electrochemical Additive Manufacturing heat sink designs. The additively manufactured heat sink designs are evaluated by comparing their thermal performance under natural convection conditions. This study presents a novel approach to heat sink design and bolsters the capability of Electrochemical Additive Manufacturing-produced heat sinks.","PeriodicalId":15663,"journal":{"name":"Journal of Electronic Packaging","volume":null,"pages":null},"PeriodicalIF":2.2,"publicationDate":"2024-07-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141826375","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Mostafa Olyaei, Sagar Singh, Kaiying Jiang, Y. Gurumukhi, Kenneth E. Goodson, Mehdi Asheghi, Nenad Miljkovic
A virtual testbed simulation framework is created for the economic, reliability, and lifetime analysis of battery thermal management control strategies in electric vehicles. The system-level model is created in the MATLAB environment using the Simscape library and custom components are developed as required. A lumped parameter coupled electro-thermal model with temperature and state of charge (SOC) dependent cell parameters is adopted from the literature to characterize battery performance. Suitable cell capacity degradation models are implemented to capture the cycle aging and calendar aging of the battery. The economic benefit of extending the lithium iron phosphate (LFP) battery lifetime by optimal thermal conditioning is weighed against the corresponding energy cost of the operation allowing for the assessment and adoption of economy-conscious strategies under different conditions. Active cooling of the battery using a vapor compression system along with a preconditioning strategy is benchmarked against passive cooling by a radiator for operating cost, battery lifetime, and net cost savings. Active cooling with precooling before fast charging can maintain optimal battery temperature but requires an additional electricity cost of 170-530 $/year, compared to passive cooling. However, the added cost is more than compensated for by the increase in battery lifetime by 1.4-1.9 years leading to a net saving of 140-550 $/year.
{"title":"Virtual Testbed for Economical and Reliability Analysis of Battery Thermal Management Control Strategies","authors":"Mostafa Olyaei, Sagar Singh, Kaiying Jiang, Y. Gurumukhi, Kenneth E. Goodson, Mehdi Asheghi, Nenad Miljkovic","doi":"10.1115/1.4065988","DOIUrl":"https://doi.org/10.1115/1.4065988","url":null,"abstract":"\u0000 A virtual testbed simulation framework is created for the economic, reliability, and lifetime analysis of battery thermal management control strategies in electric vehicles. The system-level model is created in the MATLAB environment using the Simscape library and custom components are developed as required. A lumped parameter coupled electro-thermal model with temperature and state of charge (SOC) dependent cell parameters is adopted from the literature to characterize battery performance. Suitable cell capacity degradation models are implemented to capture the cycle aging and calendar aging of the battery. The economic benefit of extending the lithium iron phosphate (LFP) battery lifetime by optimal thermal conditioning is weighed against the corresponding energy cost of the operation allowing for the assessment and adoption of economy-conscious strategies under different conditions. Active cooling of the battery using a vapor compression system along with a preconditioning strategy is benchmarked against passive cooling by a radiator for operating cost, battery lifetime, and net cost savings. Active cooling with precooling before fast charging can maintain optimal battery temperature but requires an additional electricity cost of 170-530 $/year, compared to passive cooling. However, the added cost is more than compensated for by the increase in battery lifetime by 1.4-1.9 years leading to a net saving of 140-550 $/year.","PeriodicalId":15663,"journal":{"name":"Journal of Electronic Packaging","volume":null,"pages":null},"PeriodicalIF":2.2,"publicationDate":"2024-07-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141826186","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Convective heat transfer by jet impingement cooling offers a suitable solution for high heat flux applications. Compared to techniques that rely on bulk conduction in series with convection, direct liquid impingement reduces the thermal resistance between power device hot spots and the coolant. Although capable of highly efficient cooling, static impingement devices must be designed for the worst-case cooling requirements for a transient power profile. This can result in wasted hydraulic performance. Aircraft, highway vehicles, and heavy machinery fall into this category where a substantial factor of safety is required. This work proposes a method for improving power electronics reliability by limiting temperature fluctuations at reduced coolant pressure requirements during transient power cycling using a variable area jet. Single phase jet impingement cooling is implemented in an active control scheme using a variable diameter iris mechanism as the primary nozzle architecture. In addition to pressure drop and temperature control, the active nozzle structure introduces the ability to create pulsating jet flows to further enhance the heat transfer compared to fixed-geometry nozzles. The key underlying fluid mechanics characteristic of pulsating flows is the effect of disrupting the thermal boundary layer on the electrical device surface. By introducing a variable diameter jet, eddy formation can be fine-tuned for optimal boundary layer disruption. Using the definition of the Strouhal number, vortex shedding created by the non-steady jet flows is directly correlated with the resulting Nusselt number as a function of the iris kinematics. An experimental apparatus for jet impingement thermal-fluid testing is used to evaluate the Nusselt number versus Strouhal number for a parametric study of variable diameter iris configurations. The apparatus utilizes a voice coil actuator to achieve sine and square waveforms, to vary the amplitude of actuation, and to vary the mean of actuation. Finally, power cycling with a single emulated hot spot is performed to estimate the reliability increase as a result of maintaining constant junction temperatures with the active jet impingement scheme.
{"title":"Variable Area Jet Impingement for Enhanced Junction Temperature Control of High-Power Electronics","authors":"Reece Whitt, D. Huitink","doi":"10.1115/1.4065944","DOIUrl":"https://doi.org/10.1115/1.4065944","url":null,"abstract":"\u0000 Convective heat transfer by jet impingement cooling offers a suitable solution for high heat flux applications. Compared to techniques that rely on bulk conduction in series with convection, direct liquid impingement reduces the thermal resistance between power device hot spots and the coolant. Although capable of highly efficient cooling, static impingement devices must be designed for the worst-case cooling requirements for a transient power profile. This can result in wasted hydraulic performance. Aircraft, highway vehicles, and heavy machinery fall into this category where a substantial factor of safety is required. This work proposes a method for improving power electronics reliability by limiting temperature fluctuations at reduced coolant pressure requirements during transient power cycling using a variable area jet. Single phase jet impingement cooling is implemented in an active control scheme using a variable diameter iris mechanism as the primary nozzle architecture. In addition to pressure drop and temperature control, the active nozzle structure introduces the ability to create pulsating jet flows to further enhance the heat transfer compared to fixed-geometry nozzles. The key underlying fluid mechanics characteristic of pulsating flows is the effect of disrupting the thermal boundary layer on the electrical device surface. By introducing a variable diameter jet, eddy formation can be fine-tuned for optimal boundary layer disruption. Using the definition of the Strouhal number, vortex shedding created by the non-steady jet flows is directly correlated with the resulting Nusselt number as a function of the iris kinematics. An experimental apparatus for jet impingement thermal-fluid testing is used to evaluate the Nusselt number versus Strouhal number for a parametric study of variable diameter iris configurations. The apparatus utilizes a voice coil actuator to achieve sine and square waveforms, to vary the amplitude of actuation, and to vary the mean of actuation. Finally, power cycling with a single emulated hot spot is performed to estimate the reliability increase as a result of maintaining constant junction temperatures with the active jet impingement scheme.","PeriodicalId":15663,"journal":{"name":"Journal of Electronic Packaging","volume":null,"pages":null},"PeriodicalIF":2.2,"publicationDate":"2024-07-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141828748","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pardeep Shahi, Ali Heydari, Bahareh Eslami, Vahideh Radmard, Chandraprakash Hinge, Himanshu Modi, Lochan Sai Reddy Chinthaparthy, Mohammad Tradat, D. Agonafer, Jeremy Rodriguez
Demand is growing for the dense and high-performing IT computing capacity to support artificial intelligence, deep learning, machine learning, autonomous cars, the Internet of things, etc. This led to an unprecedented growth in transistor density for high-end CPUs and GPUs, creating thermal design power (TDP) of even more than 700 watts for some of the NVIDIA existing GPUs. Cooling these high TDP chips with air cooling comes with a cost of the higher form factor of servers and noise produced by server fans close to the permissible limit. Direct-to-chip cold plate-based liquid cooling is highly efficient and becoming more reliable as the advancement in technology is taking place. Several components are used in the liquid-cooled data centers for the deployment of cold plate based direct to chip liquid cooling like cooling loops, rack manifolds, CDUs, row manifolds, quick disconnects, flow control valves, etc. Row manifolds used in liquid cooling are used to distribute secondary coolant to the rack manifolds. Characterizing these row manifolds to understand the pressure drops and flow distribution for better data center design and energy efficiency is important. In this paper, the methodology is developed to characterize the row manifolds. Water-based coolant Propylene glycol 25% was used as the coolant for the experiments and experiments were conducted at 21 °C coolant supply temperature. Two, six-port row manifolds' P-Q curves were generated, and the value of supply pressure and the flow rate were measured at each port. The results obtained from the experiments were validated by a technique called Flow Network Modeling (FNM). FNM technique uses the overall flow and thermal characteristics to represent the behavior of individual components.
为支持人工智能、深度学习、机器学习、自动驾驶汽车、物联网等，对高密度、高性能 IT 计算能力的需求与日俱增。这导致高端 CPU 和 GPU 的晶体管密度出现了前所未有的增长，英伟达（NVIDIA）现有的一些 GPU 的热设计功率（TDP）甚至超过了 700 瓦。使用风冷冷却这些高 TDP 芯片的代价是服务器的外形尺寸较高，服务器风扇产生的噪音接近允许极限。随着技术的进步，基于冷板的直接芯片液冷技术不仅效率高，而且越来越可靠。液冷数据中心在部署基于冷板的直接芯片液冷时使用了多种组件，如冷却回路、机架歧管、CDU、行歧管、快速断开装置、流量控制阀等。液体冷却中使用的排歧管用于向机架歧管分配二次冷却剂。为了更好地设计数据中心并提高能效，必须对这些列管进行特性分析，以了解其压降和流量分布。本文开发了一种方法来表征机架歧管。实验使用 25% 的水基冷却剂丙二醇作为冷却剂，实验在 21 °C 的冷却剂供应温度下进行。生成了两个六端口排流歧管的 P-Q 曲线，并测量了每个端口的供应压力值和流量。实验结果通过一种名为 "流动网络建模（FNM）"的技术进行了验证。FNM 技术使用整体流动和热特性来表示单个组件的行为。
{"title":"Methodology to Characterize Row Manifolds for High Power Direct to Chip Liquid Cooling Data Centers","authors":"Pardeep Shahi, Ali Heydari, Bahareh Eslami, Vahideh Radmard, Chandraprakash Hinge, Himanshu Modi, Lochan Sai Reddy Chinthaparthy, Mohammad Tradat, D. Agonafer, Jeremy Rodriguez","doi":"10.1115/1.4065948","DOIUrl":"https://doi.org/10.1115/1.4065948","url":null,"abstract":"\u0000 Demand is growing for the dense and high-performing IT computing capacity to support artificial intelligence, deep learning, machine learning, autonomous cars, the Internet of things, etc. This led to an unprecedented growth in transistor density for high-end CPUs and GPUs, creating thermal design power (TDP) of even more than 700 watts for some of the NVIDIA existing GPUs. Cooling these high TDP chips with air cooling comes with a cost of the higher form factor of servers and noise produced by server fans close to the permissible limit. Direct-to-chip cold plate-based liquid cooling is highly efficient and becoming more reliable as the advancement in technology is taking place. Several components are used in the liquid-cooled data centers for the deployment of cold plate based direct to chip liquid cooling like cooling loops, rack manifolds, CDUs, row manifolds, quick disconnects, flow control valves, etc. Row manifolds used in liquid cooling are used to distribute secondary coolant to the rack manifolds. Characterizing these row manifolds to understand the pressure drops and flow distribution for better data center design and energy efficiency is important. In this paper, the methodology is developed to characterize the row manifolds. Water-based coolant Propylene glycol 25% was used as the coolant for the experiments and experiments were conducted at 21 °C coolant supply temperature. Two, six-port row manifolds' P-Q curves were generated, and the value of supply pressure and the flow rate were measured at each port. The results obtained from the experiments were validated by a technique called Flow Network Modeling (FNM). FNM technique uses the overall flow and thermal characteristics to represent the behavior of individual components.","PeriodicalId":15663,"journal":{"name":"Journal of Electronic Packaging","volume":null,"pages":null},"PeriodicalIF":2.2,"publicationDate":"2024-07-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141828692","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Jessica Harsono, Joseph P. Kozak, Hala Tomey, William Yerkes, Jonathan Neville
Since most traditional spacecraft are designed to operate in a vacuum environment, forced convection cooling has seen limited use in space-applications. This paper considers an ideal candidate–the Dragonfly Lander, a rotorcraft being sent into Deep-space to conduct experiments on Saturn's largest moon, Titan. A forced convection based thermal management solution is presented for the Rotor Drive Electronics (RDE) unit, a high-power electronics box responsible for controlling the rotors that allow the Lander to fly on Titan. A thermal flow model was built in Solidworks Flow Simulation to evaluate the effectiveness of a fan system integrated into the packaging design and used as the primary method for cooling the RDE. The model was validated with temperature data collected from custom designed ground support equipment. It was found that utilizing forced convection allows temperatures of the electronics within the tightly packaged RDE to remain within operational limits when conductive and radiative heat transfer alone are insufficient. Titan's dense atmosphere results in greater mass flow rates through fans compared to on Earth, making forced convection a particularly efficient method of heat transfer. This research may guide the use of forced convection in future space missions, or non-traditional environments.
{"title":"Convection Cooling of Power Electronics Operating in Deep-Space","authors":"Jessica Harsono, Joseph P. Kozak, Hala Tomey, William Yerkes, Jonathan Neville","doi":"10.1115/1.4065947","DOIUrl":"https://doi.org/10.1115/1.4065947","url":null,"abstract":"\u0000 Since most traditional spacecraft are designed to operate in a vacuum environment, forced convection cooling has seen limited use in space-applications. This paper considers an ideal candidate–the Dragonfly Lander, a rotorcraft being sent into Deep-space to conduct experiments on Saturn's largest moon, Titan. A forced convection based thermal management solution is presented for the Rotor Drive Electronics (RDE) unit, a high-power electronics box responsible for controlling the rotors that allow the Lander to fly on Titan. A thermal flow model was built in Solidworks Flow Simulation to evaluate the effectiveness of a fan system integrated into the packaging design and used as the primary method for cooling the RDE. The model was validated with temperature data collected from custom designed ground support equipment. It was found that utilizing forced convection allows temperatures of the electronics within the tightly packaged RDE to remain within operational limits when conductive and radiative heat transfer alone are insufficient. Titan's dense atmosphere results in greater mass flow rates through fans compared to on Earth, making forced convection a particularly efficient method of heat transfer. This research may guide the use of forced convection in future space missions, or non-traditional environments.","PeriodicalId":15663,"journal":{"name":"Journal of Electronic Packaging","volume":null,"pages":null},"PeriodicalIF":2.2,"publicationDate":"2024-07-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141830446","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Ali Heydari, Qusai Soud, Mohammad Tradat, Ahmad R. Gharaibeh, Najmeh Fallahtafti, Jeremy Rodriguez, Bahgat Sammakia
As web-based AI applications are growing rapidly, server rooms face escalating computational demands, prompting enterprises to either upgrade their facilities or outsource to co-located sites. This growth strains conventional HVAC systems, which struggle to handle the substantial thermal load, often resulting in hotspots. Liquid-to-Air (L2A) Coolant Distribution Units (CDUs) emerge as a solution, efficiently cooling servers by circulating liquid coolant through cooling loops mounted on each server board. In this study, the performance of a 24-kW L2A CDU is evaluated across various scenarios, emphasizing cooling effect, stability, and reliability. Experimental tests involve a rack with three thermal test vehicles (TTVs), monitoring both liquid coolant and air sides for analysis. Tests are conducted in a limited air-conditioned environment, resembling upgraded server rooms with conventional AC systems. The study also assesses the impact of high-power density cooling units on the server room environment, measuring noise, air velocity, and ambient temperature against ASHRAE standards for human comfort. Recommendations for optimal practices and potential system improvements are included in the research, addressing the growing need for efficient cooling solutions amidst escalating computational demands.
随着基于网络的人工智能应用的快速增长，机房面临着不断升级的计算需求，这促使企业要么升级其设施，要么将其外包到共用地点。这种增长对传统的暖通空调系统造成了压力，因为传统系统难以应对巨大的热负荷，往往会产生热点。液-气（L2A）冷却液分配装置（CDU）作为一种解决方案应运而生，它通过安装在每块服务器板上的冷却回路循环液态冷却液，有效地冷却服务器。本研究评估了 24 千瓦 L2A CDU 在各种情况下的性能，重点关注冷却效果、稳定性和可靠性。实验测试包括一个带有三个热测试车（TTV）的机架，对液体冷却剂和空气两侧进行监测分析。测试在有限的空调环境中进行，类似于使用传统空调系统的升级版服务器机房。研究还评估了高功率密度冷却装置对机房环境的影响，并根据 ASHRAE 人体舒适度标准测量了噪音、风速和环境温度。研究还提出了最佳实践和潜在系统改进建议，以满足在计算需求不断升级的情况下对高效冷却解决方案日益增长的需求。
{"title":"L2A Cdus Performance and Considerations for Server Rooms Upgrade with Conventional Air Conditioning","authors":"Ali Heydari, Qusai Soud, Mohammad Tradat, Ahmad R. Gharaibeh, Najmeh Fallahtafti, Jeremy Rodriguez, Bahgat Sammakia","doi":"10.1115/1.4065942","DOIUrl":"https://doi.org/10.1115/1.4065942","url":null,"abstract":"\u0000 As web-based AI applications are growing rapidly, server rooms face escalating computational demands, prompting enterprises to either upgrade their facilities or outsource to co-located sites. This growth strains conventional HVAC systems, which struggle to handle the substantial thermal load, often resulting in hotspots. Liquid-to-Air (L2A) Coolant Distribution Units (CDUs) emerge as a solution, efficiently cooling servers by circulating liquid coolant through cooling loops mounted on each server board. In this study, the performance of a 24-kW L2A CDU is evaluated across various scenarios, emphasizing cooling effect, stability, and reliability. Experimental tests involve a rack with three thermal test vehicles (TTVs), monitoring both liquid coolant and air sides for analysis. Tests are conducted in a limited air-conditioned environment, resembling upgraded server rooms with conventional AC systems. The study also assesses the impact of high-power density cooling units on the server room environment, measuring noise, air velocity, and ambient temperature against ASHRAE standards for human comfort. Recommendations for optimal practices and potential system improvements are included in the research, addressing the growing need for efficient cooling solutions amidst escalating computational demands.","PeriodicalId":15663,"journal":{"name":"Journal of Electronic Packaging","volume":null,"pages":null},"PeriodicalIF":2.2,"publicationDate":"2024-07-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141828549","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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