Pub Date : 2020-07-01DOI: 10.1109/ITherm45881.2020.9190513
Ian Hu, Hung-Hsien Huang, Po‐Cheng Huang, Jui-Cheng Yu, C.N. Liao, M. Shih, David Tamg, C. Hung
With continuously increased power and power density, heat pipe and vapor chamber are widely used for electrical device cooling. However, to integrate them into a package for more efficient thermal dissipation is the most critical topic for next generation semiconductor device cooling. Using electroplating process for forming micro-wick structure on the copper plate is the most reasonable process for package level thermal ground plane development, which could be directly produced on the copper clad laminate substrate. The dendritic copper wick resulting from electroplating has the benefit of high performance, gravity against ability, low cost, clean, fast process and the most important thing - using existing substrate manufacturing process. In this paper, different electroplating current density and process time are evaluated for forming pore and dendrite to be the wick. Capillary limit is the dominate factor for the performance of a thermal ground plane, which is proportional to the capillary performance index. The produced wick has the index up to 0.5 um, which is as good as the high performance sintered and composite wicks; the thermal ground plane produced by the electroplated wick has the potential to have high effective thermal conductivity.
{"title":"Development of Ultra-Thin Thermal Ground Plane with High Performance Electroplated Wick","authors":"Ian Hu, Hung-Hsien Huang, Po‐Cheng Huang, Jui-Cheng Yu, C.N. Liao, M. Shih, David Tamg, C. Hung","doi":"10.1109/ITherm45881.2020.9190513","DOIUrl":"https://doi.org/10.1109/ITherm45881.2020.9190513","url":null,"abstract":"With continuously increased power and power density, heat pipe and vapor chamber are widely used for electrical device cooling. However, to integrate them into a package for more efficient thermal dissipation is the most critical topic for next generation semiconductor device cooling. Using electroplating process for forming micro-wick structure on the copper plate is the most reasonable process for package level thermal ground plane development, which could be directly produced on the copper clad laminate substrate. The dendritic copper wick resulting from electroplating has the benefit of high performance, gravity against ability, low cost, clean, fast process and the most important thing - using existing substrate manufacturing process. In this paper, different electroplating current density and process time are evaluated for forming pore and dendrite to be the wick. Capillary limit is the dominate factor for the performance of a thermal ground plane, which is proportional to the capillary performance index. The produced wick has the index up to 0.5 um, which is as good as the high performance sintered and composite wicks; the thermal ground plane produced by the electroplated wick has the potential to have high effective thermal conductivity.","PeriodicalId":193052,"journal":{"name":"2020 19th IEEE Intersociety Conference on Thermal and Thermomechanical Phenomena in Electronic Systems (ITherm)","volume":"8 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2020-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"122726633","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2020-07-01DOI: 10.1109/ITherm45881.2020.9190186
R. L. Amalfi, Filippo Cataldo, J. Marcinichen, J. Thome
This paper advances the work presented at ITHERM 2019 in which a novel thermal technology has been introduced to cool servers and datacenter racks more efficiently compared to the traditional air-based cooling solutions. As reported in the state-of-the-art and the previous papers published by the same authors, heat flux dissipation in telecom servers and high-performance computing servers is following an exponentially increasing trend in order to handle the new requirements of higher data transmission, data processing, data storage and massive device connectivity dictated by the next industrial revolution. This trend translates into the need for upgrading the capacity of existing servers and datacenter racks, as well as building new datacenters around the globe. The envisioned cooling technology, which will improve datacenter energy usage, is based on a novel combination of low-height thermosyphons operating in parallel to passively dissipate the heat generated by the servers and rack-level thermosyphons equipped with an overhead compact condenser, to dissipate the total power from the server rack to the room-level water cooling loop.The present paper is mainly focused on the experimental evaluation of the thermal performance of a 7-cm high liquid-cooled thermosyphon designed to cool a 2-U server with a maximum heat dissipation here of 200 W (but could have gone even higher) over a 4 x 4 cm2 pseudo-chip footprint. A new test setup and filling rig were designed at Nokia Bell Labs in order to accurately evaluate thermosyphon thermal performance over a wide range of heat loads, secondary side mass flow rates and inlet temperatures, using R1234ze(E) as the working fluid. A new extensive database was obtained, capturing the entire thermosyphon characteristic curve, expressed as total thermal resistance as a function of the power. Here, the experimental results are presented and discussed in detail, and they demonstrate that passive two-phase thermosyphon-based approach provides significant advantages in terms of cooling performance, energy efficiency and noise level compared to other datacenter cooling solutions available on the market or under development.
本文推进了在ITHERM 2019上提出的工作，其中引入了一种新的热技术，与传统的空气冷却解决方案相比，可以更有效地冷却服务器和数据中心机架。正如最新技术和同一作者之前发表的论文所报道的那样，为了应对下一次工业革命所要求的更高的数据传输、数据处理、数据存储和大规模设备连接的新要求，电信服务器和高性能计算服务器的热流耗散正呈指数级增长趋势。这一趋势意味着需要升级现有服务器和数据中心机架的容量，以及在全球范围内构建新的数据中心。设想中的冷却技术将改善数据中心的能源使用，它基于一种新颖的组合，即并联运行的低高度热虹吸管被动地消散服务器和机架级热虹吸管产生的热量，机架级热虹吸管配备了顶部紧凑型冷凝器，将服务器机架的总功率消散到房间级水冷却回路。本论文主要集中在一个7厘米高的液冷热虹吸管的热性能的实验评估，该设计用于冷却一个2-U服务器，在4 x 4 cm2的伪芯片占地面积上，最大散热为200 W(但可能更高)。为了准确评估热虹吸在大范围热负荷、二次侧质量流量和入口温度下的热性能，诺基亚贝尔实验室设计了一套新的测试装置和填充装置，使用R1234ze(E)作为工作流体。获得了一个新的广泛的数据库，捕获了整个热虹吸特性曲线，表示为总热阻作为功率的函数。本文对实验结果进行了详细的介绍和讨论，结果表明，与市场上或正在开发的其他数据中心冷却解决方案相比，基于被动两相热虹吸的方法在冷却性能、能源效率和噪音水平方面具有显著优势。
{"title":"Experimental Characterization of a Server-Level Thermosyphon for High-Heat Flux Dissipations","authors":"R. L. Amalfi, Filippo Cataldo, J. Marcinichen, J. Thome","doi":"10.1109/ITherm45881.2020.9190186","DOIUrl":"https://doi.org/10.1109/ITherm45881.2020.9190186","url":null,"abstract":"This paper advances the work presented at ITHERM 2019 in which a novel thermal technology has been introduced to cool servers and datacenter racks more efficiently compared to the traditional air-based cooling solutions. As reported in the state-of-the-art and the previous papers published by the same authors, heat flux dissipation in telecom servers and high-performance computing servers is following an exponentially increasing trend in order to handle the new requirements of higher data transmission, data processing, data storage and massive device connectivity dictated by the next industrial revolution. This trend translates into the need for upgrading the capacity of existing servers and datacenter racks, as well as building new datacenters around the globe. The envisioned cooling technology, which will improve datacenter energy usage, is based on a novel combination of low-height thermosyphons operating in parallel to passively dissipate the heat generated by the servers and rack-level thermosyphons equipped with an overhead compact condenser, to dissipate the total power from the server rack to the room-level water cooling loop.The present paper is mainly focused on the experimental evaluation of the thermal performance of a 7-cm high liquid-cooled thermosyphon designed to cool a 2-U server with a maximum heat dissipation here of 200 W (but could have gone even higher) over a 4 x 4 cm2 pseudo-chip footprint. A new test setup and filling rig were designed at Nokia Bell Labs in order to accurately evaluate thermosyphon thermal performance over a wide range of heat loads, secondary side mass flow rates and inlet temperatures, using R1234ze(E) as the working fluid. A new extensive database was obtained, capturing the entire thermosyphon characteristic curve, expressed as total thermal resistance as a function of the power. Here, the experimental results are presented and discussed in detail, and they demonstrate that passive two-phase thermosyphon-based approach provides significant advantages in terms of cooling performance, energy efficiency and noise level compared to other datacenter cooling solutions available on the market or under development.","PeriodicalId":193052,"journal":{"name":"2020 19th IEEE Intersociety Conference on Thermal and Thermomechanical Phenomena in Electronic Systems (ITherm)","volume":"39 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2020-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"133510103","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2020-07-01DOI: 10.1109/ITherm45881.2020.9190616
A. Alsaati, J. Weibel, A. Marconnet
Thermal management is one of the major operational concerns for data centers and accounts for a significant fraction of total power consumption. Passive immersion cooling solutions have been explored owing to their potential for offering low overall thermal resistance in very dense rack configurations where there is no room for conventional heat sinks between printed circuit boards. Further, in practice, regions of high heat flux are localized to where processing units are positioned. Non-uniform heating, as well as local hot spots, could affect thermal performance as a result of the need for rewetting of the surface with liquid during boiling. This work explores immersion cooling in submillimeter confined liquid filled gaps with localized heat sources. Specifically, this work investigates the thermofluidic characteristics of highly confined boiling surfaces. A camera is used to visualize the two-phase flow regimes and instabilities that occur prior to critical heat flux (CHF) limits. Two distinct boiling regimes are observed (namely, intermittent boiling and partial dryout). Both the heated fraction of the area within the confined region and the gap spacing affect the CHF values and thermal performance prior to CHF. The optimum thermal performance, in terms of the surface superheat, is experimentally observed for a confinement corresponding to a Bond number of 0.2. However, at this optimum condition based on surface superheat, the CHF is significantly reduced to 27% of the unconfined CHF limit. Significant additional reductions in the CHF are also experimentally observed when the adiabatic confinement surface is extended beyond the heater edge. This additional fundamental understanding of the impact of spatial confinement on the thermal performance of immersion cooling has broad implications for two-phase thermal management solutions.
{"title":"Confined Immersion Cooling in Microscale Gaps","authors":"A. Alsaati, J. Weibel, A. Marconnet","doi":"10.1109/ITherm45881.2020.9190616","DOIUrl":"https://doi.org/10.1109/ITherm45881.2020.9190616","url":null,"abstract":"Thermal management is one of the major operational concerns for data centers and accounts for a significant fraction of total power consumption. Passive immersion cooling solutions have been explored owing to their potential for offering low overall thermal resistance in very dense rack configurations where there is no room for conventional heat sinks between printed circuit boards. Further, in practice, regions of high heat flux are localized to where processing units are positioned. Non-uniform heating, as well as local hot spots, could affect thermal performance as a result of the need for rewetting of the surface with liquid during boiling. This work explores immersion cooling in submillimeter confined liquid filled gaps with localized heat sources. Specifically, this work investigates the thermofluidic characteristics of highly confined boiling surfaces. A camera is used to visualize the two-phase flow regimes and instabilities that occur prior to critical heat flux (CHF) limits. Two distinct boiling regimes are observed (namely, intermittent boiling and partial dryout). Both the heated fraction of the area within the confined region and the gap spacing affect the CHF values and thermal performance prior to CHF. The optimum thermal performance, in terms of the surface superheat, is experimentally observed for a confinement corresponding to a Bond number of 0.2. However, at this optimum condition based on surface superheat, the CHF is significantly reduced to 27% of the unconfined CHF limit. Significant additional reductions in the CHF are also experimentally observed when the adiabatic confinement surface is extended beyond the heater edge. This additional fundamental understanding of the impact of spatial confinement on the thermal performance of immersion cooling has broad implications for two-phase thermal management solutions.","PeriodicalId":193052,"journal":{"name":"2020 19th IEEE Intersociety Conference on Thermal and Thermomechanical Phenomena in Electronic Systems (ITherm)","volume":"4 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2020-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"133999268","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2020-07-01DOI: 10.1109/eucap.2016.7481097
{"title":"Awards Page","authors":"","doi":"10.1109/eucap.2016.7481097","DOIUrl":"https://doi.org/10.1109/eucap.2016.7481097","url":null,"abstract":"","PeriodicalId":193052,"journal":{"name":"2020 19th IEEE Intersociety Conference on Thermal and Thermomechanical Phenomena in Electronic Systems (ITherm)","volume":"30 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2020-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124264440","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2020-07-01DOI: 10.1109/ITherm45881.2020.9190589
Ellann Cohen, Genevieve Gaudin, R. Cardenas
Thermal engineers must design the heat exchanger geometry of an actively cooled notebook computer to meet an overall thermal resistance target for their thermal solution. Geometric parameters for the heat exchanger must be chosen to meet system, blower and thermal constrains. The typical approach is for the thermal engineer to estimate the adequate heat exchanger geometry and to iterate the design using feedback from correlations and simulations. These feedback mechanisms have trade-offs between accuracy and time often resulting in long iteration cycles to arrive at an optimal design. In this paper a neural network approach is utilized to predict heat exchanger air-flow impedance and thermal resistance using a large CFD generated training dataset. A 3-level 8-factor full factorial DOE on notebook representative heat exchanger configurations was created and solved using IcePak resulting in 3^8=6,561 distinct runs. This dataset was then used in MATLAB to train a neural network for both air-flow impedance and thermal resistance with resulting R correlation coefficients greater than 0.99. The result is an accurate and fast method for the thermal engineer to iterate the heat exchanger geometry for optimal performance. Also demonstrated in this paper is the applicability and effectiveness of using neural networks for multi-factor thermal predictions.
{"title":"Predicting Notebook Heat Exchanger Performance Using a Neural Network Approach","authors":"Ellann Cohen, Genevieve Gaudin, R. Cardenas","doi":"10.1109/ITherm45881.2020.9190589","DOIUrl":"https://doi.org/10.1109/ITherm45881.2020.9190589","url":null,"abstract":"Thermal engineers must design the heat exchanger geometry of an actively cooled notebook computer to meet an overall thermal resistance target for their thermal solution. Geometric parameters for the heat exchanger must be chosen to meet system, blower and thermal constrains. The typical approach is for the thermal engineer to estimate the adequate heat exchanger geometry and to iterate the design using feedback from correlations and simulations. These feedback mechanisms have trade-offs between accuracy and time often resulting in long iteration cycles to arrive at an optimal design. In this paper a neural network approach is utilized to predict heat exchanger air-flow impedance and thermal resistance using a large CFD generated training dataset. A 3-level 8-factor full factorial DOE on notebook representative heat exchanger configurations was created and solved using IcePak resulting in 3^8=6,561 distinct runs. This dataset was then used in MATLAB to train a neural network for both air-flow impedance and thermal resistance with resulting R correlation coefficients greater than 0.99. The result is an accurate and fast method for the thermal engineer to iterate the heat exchanger geometry for optimal performance. Also demonstrated in this paper is the applicability and effectiveness of using neural networks for multi-factor thermal predictions.","PeriodicalId":193052,"journal":{"name":"2020 19th IEEE Intersociety Conference on Thermal and Thermomechanical Phenomena in Electronic Systems (ITherm)","volume":"34 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2020-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"125164040","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2020-07-01DOI: 10.1109/ITherm45881.2020.9190272
Wenbin Tian, Michael Berktold, C. Carte, Ellen Tan
Thermocouples are widely used in industry for temperature measurement due to their high accuracy and sensitivity. However, thermocouples can act as a heatsink or a heat spreader when attached onto the top surface of small components like Voltage Regulator Modules (VRM), Capacitors, Platform Controller Hubs (PCH), and etcetera. This could alter cooling conditions of components, consequently leading to temperature measurement discrepancy on these modules. This discrepancy could be more obvious for smaller components without a heatsink or heat spreader attached. Also, the potential discrepancy relies on not only package material of components but the type of thermocouples considering the different thermocouple wire composition. This paper focuses on investigating temperature measurement discrepancies for 36-gauge type T and 36-gauge type J thermocouples on components without heatsinks or heat spreaders attached. Analysis is performed with both numerical simulation modeling using the CFD tool FloTHERM and actual testing measurements based on Intel commercial server products.
{"title":"Investigation on Reading Discrepancy of Type T and Type J Thermocouples","authors":"Wenbin Tian, Michael Berktold, C. Carte, Ellen Tan","doi":"10.1109/ITherm45881.2020.9190272","DOIUrl":"https://doi.org/10.1109/ITherm45881.2020.9190272","url":null,"abstract":"Thermocouples are widely used in industry for temperature measurement due to their high accuracy and sensitivity. However, thermocouples can act as a heatsink or a heat spreader when attached onto the top surface of small components like Voltage Regulator Modules (VRM), Capacitors, Platform Controller Hubs (PCH), and etcetera. This could alter cooling conditions of components, consequently leading to temperature measurement discrepancy on these modules. This discrepancy could be more obvious for smaller components without a heatsink or heat spreader attached. Also, the potential discrepancy relies on not only package material of components but the type of thermocouples considering the different thermocouple wire composition. This paper focuses on investigating temperature measurement discrepancies for 36-gauge type T and 36-gauge type J thermocouples on components without heatsinks or heat spreaders attached. Analysis is performed with both numerical simulation modeling using the CFD tool FloTHERM and actual testing measurements based on Intel commercial server products.","PeriodicalId":193052,"journal":{"name":"2020 19th IEEE Intersociety Conference on Thermal and Thermomechanical Phenomena in Electronic Systems (ITherm)","volume":"33 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2020-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"134236692","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2020-07-01DOI: 10.1109/ITherm45881.2020.9190530
P. Lall, Tony Thomas, K. Blecker
Remaining Useful Life (RUL) estimation of electronic packages for different conditions of vibration loads and temperatures have various applications in scheduling maintenance and component replacement effectively to reduce the cost of the same. In this study, SAC305 alloy is used as the solder alloy, and the RUL is estimated using different particle filtering and time-series analysis techniques. The test board is a lead-free SAC305 daisy chain CABGA package which is subjected to different temperatures 25oC, 55oC, 100oC and 155oC for two vibration acceleration levels of 5g and 10g. The vibration of the test board is carried out to its first natural frequency for all conditions of temperature and vibration load. Strain signals are acquired using data acquisition and signal amplifying unit from four separate locations of the test board at a frequent time interval during vibration as the parameter used for predicting failure. In-situ measurements of resistance of the packages are also measured to identify the failure of the packages during vibration. The strain signals acquired at regular intervals during vibration at different locations of the board are used to find the feature vectors that can predict failure. Principal component analysis (PCA) is used as the data reduction technique for both time and frequency-based features of the strain signal. Feature vectors are estimated from the time, frequency, and spectral content of the strain signal using different multivariate statistical techniques. The variations in the feature vectors for different conditions of temperature and load is studied by combining all the feature vector data together and analyzing it for different patterns. The correlation of the same is studied to understand the changes in the feature vectors with different conditions. The two major feature vectors that can predict the failure includes frequency and spectral content from 500 Hz to 2000 Hz of the strain signal and the instantaneous frequency of the whole strain signal.
{"title":"RUL Estimations of SAC305 Solder PCB's under Different Conditions of Temperature and Vibration Loads","authors":"P. Lall, Tony Thomas, K. Blecker","doi":"10.1109/ITherm45881.2020.9190530","DOIUrl":"https://doi.org/10.1109/ITherm45881.2020.9190530","url":null,"abstract":"Remaining Useful Life (RUL) estimation of electronic packages for different conditions of vibration loads and temperatures have various applications in scheduling maintenance and component replacement effectively to reduce the cost of the same. In this study, SAC305 alloy is used as the solder alloy, and the RUL is estimated using different particle filtering and time-series analysis techniques. The test board is a lead-free SAC305 daisy chain CABGA package which is subjected to different temperatures 25oC, 55oC, 100oC and 155oC for two vibration acceleration levels of 5g and 10g. The vibration of the test board is carried out to its first natural frequency for all conditions of temperature and vibration load. Strain signals are acquired using data acquisition and signal amplifying unit from four separate locations of the test board at a frequent time interval during vibration as the parameter used for predicting failure. In-situ measurements of resistance of the packages are also measured to identify the failure of the packages during vibration. The strain signals acquired at regular intervals during vibration at different locations of the board are used to find the feature vectors that can predict failure. Principal component analysis (PCA) is used as the data reduction technique for both time and frequency-based features of the strain signal. Feature vectors are estimated from the time, frequency, and spectral content of the strain signal using different multivariate statistical techniques. The variations in the feature vectors for different conditions of temperature and load is studied by combining all the feature vector data together and analyzing it for different patterns. The correlation of the same is studied to understand the changes in the feature vectors with different conditions. The two major feature vectors that can predict the failure includes frequency and spectral content from 500 Hz to 2000 Hz of the strain signal and the instantaneous frequency of the whole strain signal.","PeriodicalId":193052,"journal":{"name":"2020 19th IEEE Intersociety Conference on Thermal and Thermomechanical Phenomena in Electronic Systems (ITherm)","volume":"12 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2020-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"131658978","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2020-07-01DOI: 10.1109/ITherm45881.2020.9190297
Murat Parlak, E. Örs, Abuzer Özsunar
As electronic technology develops continuously, space and power allocated for cooling demands increase with time. Therefore, it becomes necessary to develop effective approaches to decrease the cooling power spent and allocated space to obtain low SWAP (Size Weight and Power) values. In this study, the application of T-Shaped branching is studied numerically in detail to get uniform temperature distribution and low-pressure drop as far as the chip junction temperature (GaN MMIC- Monolithic Microwave Integrated Circuit) is kept below the allowable temperature limit. The hotspot has a very challenging value with over 300W/cm2. The cooling liquid temperature is 45°C and the hot spot case temperature has to be kept below 100°C. In the analysis, the %60 ethylene glycol water mixture (EGW) is used as a cooling fluid and all analyses are done using constant thermal properties of materials. The microchannel heatsink has been already designed according to the given allowable volume and it is kept unchanged throughout the study. Since there are 8x2 heat sources, it is essential to guide the flow for uniform flow and temperature distribution. Because of size limitation in the cold plate, the inlet and outlet of the manifold are squeezed to a small area. It consists of two main lines, one is distributing and the other is collecting. They are designed to distribute the fluid as much as equal among the hotspots. All analyses are carried out with different flow rate input and branching is applied both free design and using the rule of Hess Murray (Construction Law) and the results of the solutions are compared and evaluated in terms of pressure drop, temperature uniformity, pumping power, flow balance
{"title":"Numerical Study of Multi Hot Spot GaN Cooling in a Cold Plate Considering Different Flow Networks","authors":"Murat Parlak, E. Örs, Abuzer Özsunar","doi":"10.1109/ITherm45881.2020.9190297","DOIUrl":"https://doi.org/10.1109/ITherm45881.2020.9190297","url":null,"abstract":"As electronic technology develops continuously, space and power allocated for cooling demands increase with time. Therefore, it becomes necessary to develop effective approaches to decrease the cooling power spent and allocated space to obtain low SWAP (Size Weight and Power) values. In this study, the application of T-Shaped branching is studied numerically in detail to get uniform temperature distribution and low-pressure drop as far as the chip junction temperature (GaN MMIC- Monolithic Microwave Integrated Circuit) is kept below the allowable temperature limit. The hotspot has a very challenging value with over 300W/cm2. The cooling liquid temperature is 45°C and the hot spot case temperature has to be kept below 100°C. In the analysis, the %60 ethylene glycol water mixture (EGW) is used as a cooling fluid and all analyses are done using constant thermal properties of materials. The microchannel heatsink has been already designed according to the given allowable volume and it is kept unchanged throughout the study. Since there are 8x2 heat sources, it is essential to guide the flow for uniform flow and temperature distribution. Because of size limitation in the cold plate, the inlet and outlet of the manifold are squeezed to a small area. It consists of two main lines, one is distributing and the other is collecting. They are designed to distribute the fluid as much as equal among the hotspots. All analyses are carried out with different flow rate input and branching is applied both free design and using the rule of Hess Murray (Construction Law) and the results of the solutions are compared and evaluated in terms of pressure drop, temperature uniformity, pumping power, flow balance","PeriodicalId":193052,"journal":{"name":"2020 19th IEEE Intersociety Conference on Thermal and Thermomechanical Phenomena in Electronic Systems (ITherm)","volume":"146 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2020-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"133138119","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2020-07-01DOI: 10.1109/ITherm45881.2020.9190378
Ashraf Alghanmi, Selvin P. Thomas, Aravinthan Gopanna, Majed A. Alrefae
Current trends of decreasing the size of electronic devices accompanied by raising their energy density imply the search for alternative thermal management materials. Reinforcing polymers with thermally conductive metallic materials is considered as one of the feasible solutions to overcome the thermal management issues for modern electronic devices. In this work, we report the thermal properties of composite materials made of polypropylene (PP) with copper (Cu) particles in different weight percentages; 0, 3, 6 and 10%. The effective thermal conductivity of the Cu/PP composites is measured by the Armfield Linear Heat Conduction experimental setup. Results show that the effective thermal conductivity of the polymer matrix increases slightly with the addition of Cu particles. This effect can be attributed to the higher thermal conductivity of the metal particles compared to the polymer as well as the effective reinforcement in the polymer matrix. In addition, thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC) techniques were utilized to characterize the Cu/PP composites. The addition of 10 weight% of Cu particles improves the temperature stability of the composites by approximately 12%. However, the melting point and the crystallization temperatures remain almost unchanged, with values of approximately 161°C and 114°C, respectively. These preliminary experiments are intended to deliberate on the influences of metal particles in polymers to enhance their thermal properties without affecting their durability and mechanical properties. Such composites will be essential components in electronic packaging to spread thermal energy efficiently.
{"title":"Thermal Properties of Copper Particles-filled Polypropylene Composites","authors":"Ashraf Alghanmi, Selvin P. Thomas, Aravinthan Gopanna, Majed A. Alrefae","doi":"10.1109/ITherm45881.2020.9190378","DOIUrl":"https://doi.org/10.1109/ITherm45881.2020.9190378","url":null,"abstract":"Current trends of decreasing the size of electronic devices accompanied by raising their energy density imply the search for alternative thermal management materials. Reinforcing polymers with thermally conductive metallic materials is considered as one of the feasible solutions to overcome the thermal management issues for modern electronic devices. In this work, we report the thermal properties of composite materials made of polypropylene (PP) with copper (Cu) particles in different weight percentages; 0, 3, 6 and 10%. The effective thermal conductivity of the Cu/PP composites is measured by the Armfield Linear Heat Conduction experimental setup. Results show that the effective thermal conductivity of the polymer matrix increases slightly with the addition of Cu particles. This effect can be attributed to the higher thermal conductivity of the metal particles compared to the polymer as well as the effective reinforcement in the polymer matrix. In addition, thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC) techniques were utilized to characterize the Cu/PP composites. The addition of 10 weight% of Cu particles improves the temperature stability of the composites by approximately 12%. However, the melting point and the crystallization temperatures remain almost unchanged, with values of approximately 161°C and 114°C, respectively. These preliminary experiments are intended to deliberate on the influences of metal particles in polymers to enhance their thermal properties without affecting their durability and mechanical properties. Such composites will be essential components in electronic packaging to spread thermal energy efficiently.","PeriodicalId":193052,"journal":{"name":"2020 19th IEEE Intersociety Conference on Thermal and Thermomechanical Phenomena in Electronic Systems (ITherm)","volume":"8 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2020-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"115342031","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2020-07-01DOI: 10.1109/ITherm45881.2020.9190437
Minghong Jian, Xin Wei, S. Hamasha, J. Suhling, P. Lall
Realistic service conditions of electronics involve varying loading scenarios. The fatigue behavior of lead-free solder alloys under varying stress amplitude cycling is still not well understood. Service life predictions based on the common linear damage accumulation rules such as Miner’s rule, ignore the effect of varying stress amplitude cycling. This can result in a large error and misunderstanding of solder alloys’ fatigue performance. No research work has investigated the Bi-doped solder alloys under varying stress amplitude cycling. In this study, individual solder joints of three different types of Sn-Ag-Cu based solder alloys (SAC305, SAC-Q, and SAC-R) are cycled at room temperature under single and varying stress amplitude. The results indicate that the linear damage accumulation rules overestimate the fatigue life (cycles) of solder alloys under varying stress amplitude cycling. There is a significant effect of varying stress amplitude cycling on Bi-doped solder joints. SAC-Q shows more fatigue resistance than SAC305 and SAC-R in both single and varying stress amplitude cases. Also, the result shows that the average inelastic work of mild stress cycling is increased after every switch from mild to harsh stress amplitude. After the crack initiation, it will dramatically increase after each switch under varying amplitude cycling.
{"title":"Effect of Varying Amplitude Cycling on SAC-Bi Solder Joint Fatigue","authors":"Minghong Jian, Xin Wei, S. Hamasha, J. Suhling, P. Lall","doi":"10.1109/ITherm45881.2020.9190437","DOIUrl":"https://doi.org/10.1109/ITherm45881.2020.9190437","url":null,"abstract":"Realistic service conditions of electronics involve varying loading scenarios. The fatigue behavior of lead-free solder alloys under varying stress amplitude cycling is still not well understood. Service life predictions based on the common linear damage accumulation rules such as Miner’s rule, ignore the effect of varying stress amplitude cycling. This can result in a large error and misunderstanding of solder alloys’ fatigue performance. No research work has investigated the Bi-doped solder alloys under varying stress amplitude cycling. In this study, individual solder joints of three different types of Sn-Ag-Cu based solder alloys (SAC305, SAC-Q, and SAC-R) are cycled at room temperature under single and varying stress amplitude. The results indicate that the linear damage accumulation rules overestimate the fatigue life (cycles) of solder alloys under varying stress amplitude cycling. There is a significant effect of varying stress amplitude cycling on Bi-doped solder joints. SAC-Q shows more fatigue resistance than SAC305 and SAC-R in both single and varying stress amplitude cases. Also, the result shows that the average inelastic work of mild stress cycling is increased after every switch from mild to harsh stress amplitude. After the crack initiation, it will dramatically increase after each switch under varying amplitude cycling.","PeriodicalId":193052,"journal":{"name":"2020 19th IEEE Intersociety Conference on Thermal and Thermomechanical Phenomena in Electronic Systems (ITherm)","volume":"27 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2020-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"115015224","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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