Pub Date : 2000-05-23DOI: 10.1109/ITHERM.2000.866802
I. Mudawar
This paper explores the recent research developments in high-heat-flux thermal management. Cooling schemes such as pool boiling, detachable heat sinks, channel flow boiling, micro-channel and mini-channel heat sinks, jet-impingement, and sprays, are discussed and compared relative to heat dissipation potential, reliability, and packaging concerns. It is demonstrated that, while different cooling options can be tailored to the specific needs of individual applications, system considerations always play a paramount role in determining the most suitable cooling scheme. It is also shown that extensive fundamental electronic cooling knowledge has been amassed over the past two decades. Yet there is now a growing need for hardware innovations rather than perturbations to those fundamental studies. An example of these innovations is the cooling of military avionics, where research findings from the electronic cooling literature have made possible the development of a new generation of cooling hardware which promise order of magnitude increases in heat dissipation compared to today's cutting edge avionics cooling schemes.
{"title":"Assessment of high-heat-flux thermal management schemes","authors":"I. Mudawar","doi":"10.1109/ITHERM.2000.866802","DOIUrl":"https://doi.org/10.1109/ITHERM.2000.866802","url":null,"abstract":"This paper explores the recent research developments in high-heat-flux thermal management. Cooling schemes such as pool boiling, detachable heat sinks, channel flow boiling, micro-channel and mini-channel heat sinks, jet-impingement, and sprays, are discussed and compared relative to heat dissipation potential, reliability, and packaging concerns. It is demonstrated that, while different cooling options can be tailored to the specific needs of individual applications, system considerations always play a paramount role in determining the most suitable cooling scheme. It is also shown that extensive fundamental electronic cooling knowledge has been amassed over the past two decades. Yet there is now a growing need for hardware innovations rather than perturbations to those fundamental studies. An example of these innovations is the cooling of military avionics, where research findings from the electronic cooling literature have made possible the development of a new generation of cooling hardware which promise order of magnitude increases in heat dissipation compared to today's cutting edge avionics cooling schemes.","PeriodicalId":201262,"journal":{"name":"ITHERM 2000. The Seventh Intersociety Conference on Thermal and Thermomechanical Phenomena in Electronic Systems (Cat. No.00CH37069)","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2000-05-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129275176","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 : 2000-05-23DOI: 10.1109/ITHERM.2000.866215
H. Zhu, Y. Guo, Wen-Ying Li, A. Tseng
Mechanical properties of solder masks are critical in the reliability performance of flip-chip packages. Many recent studies show that the mechanical properties of solder mask materials have great influence on moisture absorption, delamination at interconnections and solder fatigue life in flip-chip packages. There are also assembly process issues related to the properties of solder masks. In this article, an experimental investigation that mechanically characterizes solder one mask material is conducted. Mechanical properties such as Young's modulus, failure strength and creep behaviors are determined based on the measured data from the experiments. The testing temperature is set at two levels: 25/spl deg/C and 80/spl deg/C. The major instrument is a sophisticated micromechanical tester.
{"title":"Mechanical characterization of solder mask materials in electronic packaging applications","authors":"H. Zhu, Y. Guo, Wen-Ying Li, A. Tseng","doi":"10.1109/ITHERM.2000.866215","DOIUrl":"https://doi.org/10.1109/ITHERM.2000.866215","url":null,"abstract":"Mechanical properties of solder masks are critical in the reliability performance of flip-chip packages. Many recent studies show that the mechanical properties of solder mask materials have great influence on moisture absorption, delamination at interconnections and solder fatigue life in flip-chip packages. There are also assembly process issues related to the properties of solder masks. In this article, an experimental investigation that mechanically characterizes solder one mask material is conducted. Mechanical properties such as Young's modulus, failure strength and creep behaviors are determined based on the measured data from the experiments. The testing temperature is set at two levels: 25/spl deg/C and 80/spl deg/C. The major instrument is a sophisticated micromechanical tester.","PeriodicalId":201262,"journal":{"name":"ITHERM 2000. The Seventh Intersociety Conference on Thermal and Thermomechanical Phenomena in Electronic Systems (Cat. No.00CH37069)","volume":"141 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2000-05-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"133605435","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 : 2000-05-23DOI: 10.1109/ITHERM.2000.866198
T. Ratanawilai, B. Hunter, G. Subbarayan, D. Rose
High-sensitivity laser moire interferometry technique has proven to be invaluable in characterizing electronic packages. It is often contrasted to the classical strain gage technique as a more powerful, whole-field alternative for the characterization of electronic packages. In this paper, we present a systematic comparison of the accuracy of thermal strains measured using the moire technique to that obtained using strain gages. The effective thermal strains in approximately twenty printed circuit board specimens were measured using the two techniques. The results of the two techniques showed good overall correlation, but differed from each other by as much as 2.73 PPM. The possible sources of error in each technique are identified and discussed. Of practical significance, the measured effective coefficient of thermal expansion varied in wide range by as much as 5 PPM about the commonly used value of 17 PPM. This has been shown in a related study as causing a significant reliability impact for a plastic ball grid array package assembly.
{"title":"A comparison between moire interferometry and strain gages for effective CTE measurement in electronic packages","authors":"T. Ratanawilai, B. Hunter, G. Subbarayan, D. Rose","doi":"10.1109/ITHERM.2000.866198","DOIUrl":"https://doi.org/10.1109/ITHERM.2000.866198","url":null,"abstract":"High-sensitivity laser moire interferometry technique has proven to be invaluable in characterizing electronic packages. It is often contrasted to the classical strain gage technique as a more powerful, whole-field alternative for the characterization of electronic packages. In this paper, we present a systematic comparison of the accuracy of thermal strains measured using the moire technique to that obtained using strain gages. The effective thermal strains in approximately twenty printed circuit board specimens were measured using the two techniques. The results of the two techniques showed good overall correlation, but differed from each other by as much as 2.73 PPM. The possible sources of error in each technique are identified and discussed. Of practical significance, the measured effective coefficient of thermal expansion varied in wide range by as much as 5 PPM about the commonly used value of 17 PPM. This has been shown in a related study as causing a significant reliability impact for a plastic ball grid array package assembly.","PeriodicalId":201262,"journal":{"name":"ITHERM 2000. The Seventh Intersociety Conference on Thermal and Thermomechanical Phenomena in Electronic Systems (Cat. No.00CH37069)","volume":"31 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2000-05-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"115081703","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 : 2000-05-23DOI: 10.1109/ITHERM.2000.866838
M. Yovanovich
Thermal and mechanical models for contact, gap and joint resistances are presented for non-conforming, smooth hemi-spherical surfaces. The spreading/constriction resistance relation is applicable for light mechanical loads, and the gap resistance relation was developed for gap substances such as gases, liquids and greases. The joint resistance of the interface formed by a silicon chip and a smaller aluminum heat sink was developed and an illustrative example typical of microelectronic applications was presented.
{"title":"Thermal-mechanical models for non-conforming surface contacts","authors":"M. Yovanovich","doi":"10.1109/ITHERM.2000.866838","DOIUrl":"https://doi.org/10.1109/ITHERM.2000.866838","url":null,"abstract":"Thermal and mechanical models for contact, gap and joint resistances are presented for non-conforming, smooth hemi-spherical surfaces. The spreading/constriction resistance relation is applicable for light mechanical loads, and the gap resistance relation was developed for gap substances such as gases, liquids and greases. The joint resistance of the interface formed by a silicon chip and a smaller aluminum heat sink was developed and an illustrative example typical of microelectronic applications was presented.","PeriodicalId":201262,"journal":{"name":"ITHERM 2000. The Seventh Intersociety Conference on Thermal and Thermomechanical Phenomena in Electronic Systems (Cat. No.00CH37069)","volume":"39 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2000-05-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"123062428","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 : 2000-05-23DOI: 10.1109/ITHERM.2000.866181
Seok-Hwan Moon, Choon‐Gi Choi, G. Hwang, Tae Coo Choy
The thermal density of electronic parts and systems has been increased continuously as high speed and high density are required for them. The heat generation of the CPU of a notebook PC of higher than the Pentium-II grade has been recently increased to be more than 10 W, and the available packaging space has been compacted. Therefore, it has become inevitable to perform cooling by using miniature heat pipes. In the present study, new woven-wired-type wick with a large capillary limit and a high productivity has been developed, and heat pipes with the diameter of 3 mm or 4 mm to cooling of small-sized electronic parts such as CPU of a notebook PC. Have been designed and manufactured. Further, in as much as the operational characteristics of miniature heat pipes (MHPs) with the diameter of 3 mm or 4 mm are different from those of general medium-sized heat pipes, a performance test has been performed in order to review heat-transfer characteristics and affects of various factors on the performance of MHPs. The operational factors include charging ratio of working fluid, the total length of heat pipes, lengths of an evaporator and a condenser, inclination of installation, number of wick strands, thermal load, etc. The limiting powers of 3 mm MHP and 4 mm MHP are shown to be 6.8 W and 19.5 W, respectively, with angle of inclination of -5/spl deg/. These show that there is a high possibility of application if one or two MHPs are installed for cooling of CPU more than 10 W.
随着电子器件和系统对高速度和高密度的要求，其热密度不断提高。最近，Pentium-II以上等级的笔记本电脑的CPU发热量已提高到10w以上，并且可用的封装空间已被压缩。因此，利用微型热管进行冷却已成为必然。本研究开发了一种具有大毛细极限和高生产率的新型编织丝型芯，以及直径为3mm或4mm的热管，用于笔记本电脑CPU等小型电子部件的冷却。已被设计和制造。此外，针对直径为3mm和4mm的微型热管的工作特性与一般中型热管的不同，进行了性能测试，以审查传热特性以及各种因素对微型热管性能的影响。运行因素包括工质充注比、热管总长度、蒸发器和冷凝器长度、安装倾角、芯束数、热负荷等。3 mm MHP和4 mm MHP的极限功率分别为6.8 W和19.5 W，倾斜角为-5/spl°/。这表明，如果在10w以上的CPU上安装1 ~ 2台mhp，应用的可能性很大。
{"title":"Experimental study on performance of a miniature heat pipe with woven-wired wick","authors":"Seok-Hwan Moon, Choon‐Gi Choi, G. Hwang, Tae Coo Choy","doi":"10.1109/ITHERM.2000.866181","DOIUrl":"https://doi.org/10.1109/ITHERM.2000.866181","url":null,"abstract":"The thermal density of electronic parts and systems has been increased continuously as high speed and high density are required for them. The heat generation of the CPU of a notebook PC of higher than the Pentium-II grade has been recently increased to be more than 10 W, and the available packaging space has been compacted. Therefore, it has become inevitable to perform cooling by using miniature heat pipes. In the present study, new woven-wired-type wick with a large capillary limit and a high productivity has been developed, and heat pipes with the diameter of 3 mm or 4 mm to cooling of small-sized electronic parts such as CPU of a notebook PC. Have been designed and manufactured. Further, in as much as the operational characteristics of miniature heat pipes (MHPs) with the diameter of 3 mm or 4 mm are different from those of general medium-sized heat pipes, a performance test has been performed in order to review heat-transfer characteristics and affects of various factors on the performance of MHPs. The operational factors include charging ratio of working fluid, the total length of heat pipes, lengths of an evaporator and a condenser, inclination of installation, number of wick strands, thermal load, etc. The limiting powers of 3 mm MHP and 4 mm MHP are shown to be 6.8 W and 19.5 W, respectively, with angle of inclination of -5/spl deg/. These show that there is a high possibility of application if one or two MHPs are installed for cooling of CPU more than 10 W.","PeriodicalId":201262,"journal":{"name":"ITHERM 2000. The Seventh Intersociety Conference on Thermal and Thermomechanical Phenomena in Electronic Systems (Cat. No.00CH37069)","volume":"18 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2000-05-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"116816545","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 : 2000-05-23DOI: 10.1109/ITHERM.2000.866190
M. Sakane, H. Yamamoto
This paper studies creep-fatigue life prediction under shear loading by making extensive torsion creep-fatigue experiments using four kinds of strain waves. The linear damage rule, the strain range partitioning method, the frequency modified fatigue life and the ductility exhaustion model were applied to the experimental data, but no methods accurately predicted the creep-fatigue life. A new method based on the strain rate ratio, which predicted the creep-fatigue life within a factor of 4 scatter band, was developed.
{"title":"A strain rate ratio approach for assessing creep-fatigue life of 63Sn-37Pb solder under shear loading","authors":"M. Sakane, H. Yamamoto","doi":"10.1109/ITHERM.2000.866190","DOIUrl":"https://doi.org/10.1109/ITHERM.2000.866190","url":null,"abstract":"This paper studies creep-fatigue life prediction under shear loading by making extensive torsion creep-fatigue experiments using four kinds of strain waves. The linear damage rule, the strain range partitioning method, the frequency modified fatigue life and the ductility exhaustion model were applied to the experimental data, but no methods accurately predicted the creep-fatigue life. A new method based on the strain rate ratio, which predicted the creep-fatigue life within a factor of 4 scatter band, was developed.","PeriodicalId":201262,"journal":{"name":"ITHERM 2000. The Seventh Intersociety Conference on Thermal and Thermomechanical Phenomena in Electronic Systems (Cat. No.00CH37069)","volume":"17 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2000-05-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"125224740","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 : 2000-05-23DOI: 10.1109/ITHERM.2000.866183
R.A. Sahan
Low-order dynamical models of transitional natural convective air-cooling system in a vertical channel with periodically repeated discrete heat sources are developed. Proper orthogonal decomposition (POD) methodology has been applied to supercritical oscillatory solutions, obtained by solving the flow governing partial differential equations (PDEs) with a spectral element method at Grashof number, Gr=25000. POD is used to extract the empirical eigenfunctions, to compress the data and to identify the organized spatio-temporal structures. Low-order models (LOMs), consisting of reduced number of nonlinear ordinary differential equations (ODEs), are derived using the computed empirical eigenfunctions as basis functions and applying Galerkin projection (GP). The ability of the reduced models to describe the dynamics of the flow and temperature fields at design conditions is studied. In this study, at least four modes for both velocity and temperature are required to predict self-sustained oscillations in time. The LOM predictions based on four modes are in excellent agreement with the full model results, capturing the short- and long-time nonlinear dynamical behavior of the thermo-fluid system. The developed LOMs may be used to make feasible parametric studies with less computational effort and storage requirements, to investigate stability behavior of the forced/natural convective air-cooling systems, and to explore possible flow control strategies.
{"title":"Low-order dynamical modeling of natural convective air-cooling system in a vertical channel","authors":"R.A. Sahan","doi":"10.1109/ITHERM.2000.866183","DOIUrl":"https://doi.org/10.1109/ITHERM.2000.866183","url":null,"abstract":"Low-order dynamical models of transitional natural convective air-cooling system in a vertical channel with periodically repeated discrete heat sources are developed. Proper orthogonal decomposition (POD) methodology has been applied to supercritical oscillatory solutions, obtained by solving the flow governing partial differential equations (PDEs) with a spectral element method at Grashof number, Gr=25000. POD is used to extract the empirical eigenfunctions, to compress the data and to identify the organized spatio-temporal structures. Low-order models (LOMs), consisting of reduced number of nonlinear ordinary differential equations (ODEs), are derived using the computed empirical eigenfunctions as basis functions and applying Galerkin projection (GP). The ability of the reduced models to describe the dynamics of the flow and temperature fields at design conditions is studied. In this study, at least four modes for both velocity and temperature are required to predict self-sustained oscillations in time. The LOM predictions based on four modes are in excellent agreement with the full model results, capturing the short- and long-time nonlinear dynamical behavior of the thermo-fluid system. The developed LOMs may be used to make feasible parametric studies with less computational effort and storage requirements, to investigate stability behavior of the forced/natural convective air-cooling systems, and to explore possible flow control strategies.","PeriodicalId":201262,"journal":{"name":"ITHERM 2000. The Seventh Intersociety Conference on Thermal and Thermomechanical Phenomena in Electronic Systems (Cat. No.00CH37069)","volume":"23 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2000-05-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"126535609","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 : 2000-05-23DOI: 10.1109/ITHERM.2000.866214
W. Xie, S. Sitaraman
Research on system-on-package (SOP) with integrated substrate is being pursued at Georgia Tech. The integrated substrate contains embedded thin-film passive components in a multilayered substrate to achieve higher performance, lower cost, smaller size and lighter weight. However, as in all multilayered structures, SOP integrated substrate could have higher interfacial stresses and therefore could have interfacial delamination induced by material properties mismatch under thermal loading, if not carefully designed and fabricated. In this study, numerical analyses have been performed to investigate interfacial delamination propagation in SOP integrated substrate under thermal loading. Three candidate base layer materials and two dielectric layer materials have been studied. Recommendations for reducing delamination propagation were suggested. Further study is being conducted to investigate effects of time and temperature dependent material properties and cyclic thermal loading conditions.
{"title":"Numerical study of interfacial delamination in a system-on-package (SOP) integrated substrate under thermal loading","authors":"W. Xie, S. Sitaraman","doi":"10.1109/ITHERM.2000.866214","DOIUrl":"https://doi.org/10.1109/ITHERM.2000.866214","url":null,"abstract":"Research on system-on-package (SOP) with integrated substrate is being pursued at Georgia Tech. The integrated substrate contains embedded thin-film passive components in a multilayered substrate to achieve higher performance, lower cost, smaller size and lighter weight. However, as in all multilayered structures, SOP integrated substrate could have higher interfacial stresses and therefore could have interfacial delamination induced by material properties mismatch under thermal loading, if not carefully designed and fabricated. In this study, numerical analyses have been performed to investigate interfacial delamination propagation in SOP integrated substrate under thermal loading. Three candidate base layer materials and two dielectric layer materials have been studied. Recommendations for reducing delamination propagation were suggested. Further study is being conducted to investigate effects of time and temperature dependent material properties and cyclic thermal loading conditions.","PeriodicalId":201262,"journal":{"name":"ITHERM 2000. The Seventh Intersociety Conference on Thermal and Thermomechanical Phenomena in Electronic Systems (Cat. No.00CH37069)","volume":"107 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2000-05-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124680574","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 : 2000-05-23DOI: 10.1109/ITHERM.2000.866834
Ann Garrison Damn, R. Osiander, J. Champion, Ted Swanson, D. Douglas, Lisa M. Grob
This paper discusses a new technology for variable emissivity (vari-e) radiator surfaces, which has significant advantages over traditional radiators and promises an alternative design technique for future spacecraft thermal control systems. All spacecraft rely on radiative surfaces to dissipate waste heat. These radiators have special coatings, typically with a low solar absorptivity and a high infrared-red emissivity, that are intended to optimize performance under the expected heat load and thermal sink environment. The dynamics of the heat loads and thermal environment make it a challenge to properly size the radiator and often require some means of regulating the heat rejection rate of the radiators in order to achieve proper thermal balance. Specialized thermal control coatings, which can passively or actively adjust their emissivity offer an attractive solution to these design challenges. Such systems would allow intelligent control of the rate of heat loss from a radiator in response to heat load and thermal environmental variations. Intelligent thermal control through variable emissivity systems is well suited for nano and pico spacecraft applications where large thermal fluctuations are expected due to the small thermal mass and limited electric resources. Presently there are three different types of vari-e technologies under development: Micro Electro-Mechanical Systems (MEMS) louvers, Electrochromic devices, and Electrophoretic devices. This paper will describe several prototypes of micromachined (MEMS) louvers and experimental results for the emissivity variations measured on theses prototypes. It will further discuss possible actuation mechanisms and space reliability aspects for different designs. Finally, for comparison, parametric evaluations of the thermal performance of the new vari-e technology and standard thermal control systems are also presented in this paper.
{"title":"Variable emissivity through MEMS technology","authors":"Ann Garrison Damn, R. Osiander, J. Champion, Ted Swanson, D. Douglas, Lisa M. Grob","doi":"10.1109/ITHERM.2000.866834","DOIUrl":"https://doi.org/10.1109/ITHERM.2000.866834","url":null,"abstract":"This paper discusses a new technology for variable emissivity (vari-e) radiator surfaces, which has significant advantages over traditional radiators and promises an alternative design technique for future spacecraft thermal control systems. All spacecraft rely on radiative surfaces to dissipate waste heat. These radiators have special coatings, typically with a low solar absorptivity and a high infrared-red emissivity, that are intended to optimize performance under the expected heat load and thermal sink environment. The dynamics of the heat loads and thermal environment make it a challenge to properly size the radiator and often require some means of regulating the heat rejection rate of the radiators in order to achieve proper thermal balance. Specialized thermal control coatings, which can passively or actively adjust their emissivity offer an attractive solution to these design challenges. Such systems would allow intelligent control of the rate of heat loss from a radiator in response to heat load and thermal environmental variations. Intelligent thermal control through variable emissivity systems is well suited for nano and pico spacecraft applications where large thermal fluctuations are expected due to the small thermal mass and limited electric resources. Presently there are three different types of vari-e technologies under development: Micro Electro-Mechanical Systems (MEMS) louvers, Electrochromic devices, and Electrophoretic devices. This paper will describe several prototypes of micromachined (MEMS) louvers and experimental results for the emissivity variations measured on theses prototypes. It will further discuss possible actuation mechanisms and space reliability aspects for different designs. Finally, for comparison, parametric evaluations of the thermal performance of the new vari-e technology and standard thermal control systems are also presented in this paper.","PeriodicalId":201262,"journal":{"name":"ITHERM 2000. The Seventh Intersociety Conference on Thermal and Thermomechanical Phenomena in Electronic Systems (Cat. No.00CH37069)","volume":"46 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2000-05-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"126534835","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 : 2000-05-23DOI: 10.1109/ITHERM.2000.866809
T. Zapach, T. Newhouse, J. Taylor, P. Thomasing
An analytical model for the optimization of pin fin heatsinks was developed. The model is based on correlations of flow resistance and heat transfer from studies of tube bank heat exchangers. Experimental verification of the model shows that, with some minor modification to the heat transfer correlations, it reasonably represents heat transfer trends. Flow resistance trends are under-predicted for both inline and staggered pin arrangements. Even with these limitations this tool is useful for the optimization and pin arrangement selection of pin fin heatsinks.
{"title":"Experimental verification of a model for the optimization of pin fin heatsinks","authors":"T. Zapach, T. Newhouse, J. Taylor, P. Thomasing","doi":"10.1109/ITHERM.2000.866809","DOIUrl":"https://doi.org/10.1109/ITHERM.2000.866809","url":null,"abstract":"An analytical model for the optimization of pin fin heatsinks was developed. The model is based on correlations of flow resistance and heat transfer from studies of tube bank heat exchangers. Experimental verification of the model shows that, with some minor modification to the heat transfer correlations, it reasonably represents heat transfer trends. Flow resistance trends are under-predicted for both inline and staggered pin arrangements. Even with these limitations this tool is useful for the optimization and pin arrangement selection of pin fin heatsinks.","PeriodicalId":201262,"journal":{"name":"ITHERM 2000. The Seventh Intersociety Conference on Thermal and Thermomechanical Phenomena in Electronic Systems (Cat. No.00CH37069)","volume":"16 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2000-05-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"134448527","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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