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/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/ITherm45881.2020.9190531
T. Olatunji, Mahsa Montazeri, D. Huitink
The need to increase the power density in electronic devices is being limited by the reliability of power devices and its components. To counter this problem, devices will need to have nonconventional designs and features that can help mitigate thermal and mechanical stress concerns, in order to improve failure rates at critical locations within power devices and packages. A major problem plaguing power densification arises from the reliability of the device due to thermomechanical stresses and strains at interfaces that are amplified in harsh environment electronics such as in electric vehicle applications, where temperature extremes are common. One solution to enabling longer interconnect life lies in compliant interconnects, wherein various compliant geometries using photolithography-based approaches to fabricate suspended structures for allowing deflection between chip and substrate. These features reduce stress on the interconnection itself, resulting in improved lifetimes, particularly in solder joints. Yet these structures usually come at a cost of lateral many additional processing steps during interconnect fabrication. In this work, we present an additive approach to fabricate copper-plated compliant interconnects directly on printed circuit boards (PCBs). This approach can accomplish similar thermomechanical stress alleviation to formerly reported methods, but with fewer process steps, and new geometry availability. This work reports the fabrication procedure, process engineering and characterization in addition to the compliance evaluation for a semi-subtractive structure manufacturing process enabled through a novel additive manufacturing methodology.
{"title":"Fabrication of Copper Compliant Iinterconnects on a Printed Circuit Board: An Additive Approach","authors":"T. Olatunji, Mahsa Montazeri, D. Huitink","doi":"10.1109/ITherm45881.2020.9190531","DOIUrl":"https://doi.org/10.1109/ITherm45881.2020.9190531","url":null,"abstract":"The need to increase the power density in electronic devices is being limited by the reliability of power devices and its components. To counter this problem, devices will need to have nonconventional designs and features that can help mitigate thermal and mechanical stress concerns, in order to improve failure rates at critical locations within power devices and packages. A major problem plaguing power densification arises from the reliability of the device due to thermomechanical stresses and strains at interfaces that are amplified in harsh environment electronics such as in electric vehicle applications, where temperature extremes are common. One solution to enabling longer interconnect life lies in compliant interconnects, wherein various compliant geometries using photolithography-based approaches to fabricate suspended structures for allowing deflection between chip and substrate. These features reduce stress on the interconnection itself, resulting in improved lifetimes, particularly in solder joints. Yet these structures usually come at a cost of lateral many additional processing steps during interconnect fabrication. In this work, we present an additive approach to fabricate copper-plated compliant interconnects directly on printed circuit boards (PCBs). This approach can accomplish similar thermomechanical stress alleviation to formerly reported methods, but with fewer process steps, and new geometry availability. This work reports the fabrication procedure, process engineering and characterization in addition to the compliance evaluation for a semi-subtractive structure manufacturing process enabled through a novel additive manufacturing methodology.","PeriodicalId":193052,"journal":{"name":"2020 19th IEEE Intersociety Conference on Thermal and Thermomechanical Phenomena in Electronic Systems (ITherm)","volume":"109 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":"115669910","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}
Pub Date : 2020-07-01DOI: 10.1109/ITherm45881.2020.9190455
P. Lall, Jinesh Narangaparambil
Flexible and stretchable devices have attracted great interest in the printed electronics industry for health monitoring of critical infrastructure applications. Additive printing technology is gaining much popularity for fabrication of flexible circuits due to its ease of setup, cost-efficient and its ability of miniaturization. Aerosol Jet Printing is one of the methods of additive printing, which is a popular technology due to non-contact printing, precision and good quality print on flexible substrates, low setup time and reduction of fabrication cost. All these versatilities can be easily applied sensors for health monitoring. Ability to print sensors allows for a tighter integration into the underlying structures providing new opportunities for placement of sensor ever closer to the point of measurement than possible with discrete sensors. In this paper, the humidity sensor is designed and fabricated with the help of aerosol-jet printing on paper substrate. Two kinds of papers with different surface quality used in this study with varied number of passes of the printed conductive line. The printed sensors were tested under the controlled environment of 30°C and relative humidity varying in the range of 20% to 90%. The sensor was also tested for its performance in up sweep and down sweep of relative humidity to quantify the hysteresis. Long-term stability and repeatability have also been quantified.
{"title":"Process Development and Performance Analysis of Additively Printed Humidity Sensor using Aerosol Jet Printing","authors":"P. Lall, Jinesh Narangaparambil","doi":"10.1109/ITherm45881.2020.9190455","DOIUrl":"https://doi.org/10.1109/ITherm45881.2020.9190455","url":null,"abstract":"Flexible and stretchable devices have attracted great interest in the printed electronics industry for health monitoring of critical infrastructure applications. Additive printing technology is gaining much popularity for fabrication of flexible circuits due to its ease of setup, cost-efficient and its ability of miniaturization. Aerosol Jet Printing is one of the methods of additive printing, which is a popular technology due to non-contact printing, precision and good quality print on flexible substrates, low setup time and reduction of fabrication cost. All these versatilities can be easily applied sensors for health monitoring. Ability to print sensors allows for a tighter integration into the underlying structures providing new opportunities for placement of sensor ever closer to the point of measurement than possible with discrete sensors. In this paper, the humidity sensor is designed and fabricated with the help of aerosol-jet printing on paper substrate. Two kinds of papers with different surface quality used in this study with varied number of passes of the printed conductive line. The printed sensors were tested under the controlled environment of 30°C and relative humidity varying in the range of 20% to 90%. The sensor was also tested for its performance in up sweep and down sweep of relative humidity to quantify the hysteresis. Long-term stability and repeatability have also been quantified.","PeriodicalId":193052,"journal":{"name":"2020 19th IEEE Intersociety Conference on Thermal and Thermomechanical Phenomena in Electronic Systems (ITherm)","volume":"28 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":"123133663","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/ITherm45881.2020.9190446
P. Lall, Ved Soni, Scott Miller
The major contributor to the boost in flexible power source research is the growing need for wearable devices, fitness accessories and biomedical equipment. Flexible batteries are required to sustain repetitive mechanical stresses during motion in addition to the usual desirable features such as high capacity, fast charge capability and low susceptibility towards degradation. The investigation of cyclic deformation of batteries is limited and the reported studies are conducted for a shorter number of flex cycles and that too with manual flexing instead of a deformation setup. The purpose of this research is to understand the degradation behavior of lithium ion batteries subjected to cyclic flexing deformation along with accelerated deep charge-discharge life cycling. Furthermore, the power sources are tested for the combined effect of mechanical and electrical loads by varying the charge C-Rate. By measuring the battery current and terminal voltage, assessment of its capacity and battery state of health is conducted. Finally, the state of health of the battery is correlated to these parameters with a regression model.
{"title":"Effect of Dynamic Folding with Varying Fold Orientations and C-rates on Flexible Power Source Capacity Degradation","authors":"P. Lall, Ved Soni, Scott Miller","doi":"10.1109/ITherm45881.2020.9190446","DOIUrl":"https://doi.org/10.1109/ITherm45881.2020.9190446","url":null,"abstract":"The major contributor to the boost in flexible power source research is the growing need for wearable devices, fitness accessories and biomedical equipment. Flexible batteries are required to sustain repetitive mechanical stresses during motion in addition to the usual desirable features such as high capacity, fast charge capability and low susceptibility towards degradation. The investigation of cyclic deformation of batteries is limited and the reported studies are conducted for a shorter number of flex cycles and that too with manual flexing instead of a deformation setup. The purpose of this research is to understand the degradation behavior of lithium ion batteries subjected to cyclic flexing deformation along with accelerated deep charge-discharge life cycling. Furthermore, the power sources are tested for the combined effect of mechanical and electrical loads by varying the charge C-Rate. By measuring the battery current and terminal voltage, assessment of its capacity and battery state of health is conducted. Finally, the state of health of the battery is correlated to these parameters with a regression model.","PeriodicalId":193052,"journal":{"name":"2020 19th IEEE Intersociety Conference on Thermal and Thermomechanical Phenomena in Electronic Systems (ITherm)","volume":"5 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":"125398361","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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