Pub Date : 2017-05-01DOI: 10.1109/ITHERM.2017.7992567
M. Kushare, A. Jhaveri, A. Bhargav
Optical spectrometers have been of interest in remote sensing because of their ability to decipher an image scene based on its spectrum. Fore-optics, glass window, cold shield, order sorting filters (OSF), focal plane array (FPA) and cryo-cooler are integral parts of a spectrometer assembly. It can be divided into two parts: Fore optics & Integrated Detector Dewar Cooling Assembly (IDDCA). Optimum size of cryo-cooler ought to be known as weight constraints are critical in payload design. Cooling load on cryo-cooler depends on the ability of assembly's parts to absorb, transmit and radiate energy emanating from distant scene and incident on spectrometer's aperture. The experimentation with small scale components is expensive and requires sophisticated measuring and calibration techniques. Efforts have been made to develop a computational model which can hypothesize thermal parameters of IDDCA and their interdependency. This study has been carried out for the assembly using Ray optics and Heat transfer modules of COMSOL Multiphysics in the wavelength range of 800 to 5000 nm. This model examines the distribution of temperature and total heat flux on FPA in order to maintain its low temperature 90 K) for maintaining image resolution.
{"title":"Radiation heat transfer analysis of spectrometer's Dewar Cooling Assembly","authors":"M. Kushare, A. Jhaveri, A. Bhargav","doi":"10.1109/ITHERM.2017.7992567","DOIUrl":"https://doi.org/10.1109/ITHERM.2017.7992567","url":null,"abstract":"Optical spectrometers have been of interest in remote sensing because of their ability to decipher an image scene based on its spectrum. Fore-optics, glass window, cold shield, order sorting filters (OSF), focal plane array (FPA) and cryo-cooler are integral parts of a spectrometer assembly. It can be divided into two parts: Fore optics & Integrated Detector Dewar Cooling Assembly (IDDCA). Optimum size of cryo-cooler ought to be known as weight constraints are critical in payload design. Cooling load on cryo-cooler depends on the ability of assembly's parts to absorb, transmit and radiate energy emanating from distant scene and incident on spectrometer's aperture. The experimentation with small scale components is expensive and requires sophisticated measuring and calibration techniques. Efforts have been made to develop a computational model which can hypothesize thermal parameters of IDDCA and their interdependency. This study has been carried out for the assembly using Ray optics and Heat transfer modules of COMSOL Multiphysics in the wavelength range of 800 to 5000 nm. This model examines the distribution of temperature and total heat flux on FPA in order to maintain its low temperature 90 K) for maintaining image resolution.","PeriodicalId":387542,"journal":{"name":"2017 16th IEEE Intersociety Conference on Thermal and Thermomechanical Phenomena in Electronic Systems (ITherm)","volume":"12 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2017-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129807011","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 : 2017-05-01DOI: 10.1109/ITHERM.2017.7992545
W. Gerstler, Daniel J. Erno
Currently, additive manufacturing advancements are continuous and frequent. Heat transfer equipment, such as heat exchangers, are an exemplary application that benefits from additive manufacturing innovation. Attributes such as low weight and volume are attainable using additive designs. Additive also allows monolithic builds with no braze joints required. A novel geometry was conceptualized, built, tested, and compared to the test results from a conventionally manufactured heat exchanger. Both heat exchangers were designed to meet the same heat transfer and pressure drop specifications — those of a commercial fuel-cooled oil cooler. Results show the additive design has equivalent heat transfer to the conventional heat exchanger and meets the pressure drop specifications — while having 66% lower weight when built with the same material and 50% lower volume. Additionally, the additive build requires no braze joints thus is expected to have improved reliability compared to the conventional design. The additive heat exchanger design was successfully built, and passed vacuum leak tests, using four different materials: Aluminum, Titanium 6–4, Cobalt Chrome, and Inconel-718.
{"title":"Introduction of an additively manufactured multi-furcating heat exchanger","authors":"W. Gerstler, Daniel J. Erno","doi":"10.1109/ITHERM.2017.7992545","DOIUrl":"https://doi.org/10.1109/ITHERM.2017.7992545","url":null,"abstract":"Currently, additive manufacturing advancements are continuous and frequent. Heat transfer equipment, such as heat exchangers, are an exemplary application that benefits from additive manufacturing innovation. Attributes such as low weight and volume are attainable using additive designs. Additive also allows monolithic builds with no braze joints required. A novel geometry was conceptualized, built, tested, and compared to the test results from a conventionally manufactured heat exchanger. Both heat exchangers were designed to meet the same heat transfer and pressure drop specifications — those of a commercial fuel-cooled oil cooler. Results show the additive design has equivalent heat transfer to the conventional heat exchanger and meets the pressure drop specifications — while having 66% lower weight when built with the same material and 50% lower volume. Additionally, the additive build requires no braze joints thus is expected to have improved reliability compared to the conventional design. The additive heat exchanger design was successfully built, and passed vacuum leak tests, using four different materials: Aluminum, Titanium 6–4, Cobalt Chrome, and Inconel-718.","PeriodicalId":387542,"journal":{"name":"2017 16th IEEE Intersociety Conference on Thermal and Thermomechanical Phenomena in Electronic Systems (ITherm)","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2017-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"116154719","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 : 2017-05-01DOI: 10.1109/ITHERM.2017.7992462
A. Vallabhaneni, M. Gupta, Satish Kumar
AlGaN/GaN based high electron mobility transistors (AG-HEMTs) are strong candidates for the future high power and high frequency applications. But the formation of hot-spots and high temperature in these localized regions can limit their applications due to performance degradation and break-down. Understanding the underlying thermal transport processes will be an important step towards solving heat dissipation challenges in these devices. The objectives of the current study is to develop a multi-scale thermal transport model based on Boltzmann Transport Equation (BTE) to predict the hot-spot temperature accurately for a given bias voltage. At present, there are no reliable models to predict the energy (temperature) distribution near the hot spot in these devices. We developed coupled electro-thermal model to extract key information about hot-spot location and dissipated power. This information is further utilized to investigate the thermal performance of the device using BTE based model which can provide detailed view of the non-equilibrium nature of the phonon transport in the hot-spot. The interface between GaN and silicon substrate is treated with diffusive mismatch model (DMM). We calculated the spatial temperature distribution in a GaN device on silicon substrate and estimated the maximum temperature of hot spots. We also compared BTE and Fourier models for estimating the temperature distribution and found that Fourier model would significantly under predict the hot spot temperature. The multi-scale model can be used to investigate thermal transport in multi-finger devices and to explore the effect of cross-talk between different fingers.
{"title":"Thermal transport in high electron mobility transistors: A Boltzmann transport equation study","authors":"A. Vallabhaneni, M. Gupta, Satish Kumar","doi":"10.1109/ITHERM.2017.7992462","DOIUrl":"https://doi.org/10.1109/ITHERM.2017.7992462","url":null,"abstract":"AlGaN/GaN based high electron mobility transistors (AG-HEMTs) are strong candidates for the future high power and high frequency applications. But the formation of hot-spots and high temperature in these localized regions can limit their applications due to performance degradation and break-down. Understanding the underlying thermal transport processes will be an important step towards solving heat dissipation challenges in these devices. The objectives of the current study is to develop a multi-scale thermal transport model based on Boltzmann Transport Equation (BTE) to predict the hot-spot temperature accurately for a given bias voltage. At present, there are no reliable models to predict the energy (temperature) distribution near the hot spot in these devices. We developed coupled electro-thermal model to extract key information about hot-spot location and dissipated power. This information is further utilized to investigate the thermal performance of the device using BTE based model which can provide detailed view of the non-equilibrium nature of the phonon transport in the hot-spot. The interface between GaN and silicon substrate is treated with diffusive mismatch model (DMM). We calculated the spatial temperature distribution in a GaN device on silicon substrate and estimated the maximum temperature of hot spots. We also compared BTE and Fourier models for estimating the temperature distribution and found that Fourier model would significantly under predict the hot spot temperature. The multi-scale model can be used to investigate thermal transport in multi-finger devices and to explore the effect of cross-talk between different fingers.","PeriodicalId":387542,"journal":{"name":"2017 16th IEEE Intersociety Conference on Thermal and Thermomechanical Phenomena in Electronic Systems (ITherm)","volume":"75 Suppl 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2017-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"116469119","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 : 2017-05-01DOI: 10.1109/ITHERM.2017.7992528
B. Rogié, E. Monier-Vinard, N. Nguyen, N. Laraqi, V. Bissuel, O. Daniel
Burying active chips into internal layers of a Printed Wiring Board (PWB) allows increasing the density of an electronic board but leads to higher thermal stress inside its structure. To help the designers for analyzing the limits of the in-layer power dissipation, various analytical approaches were investigated. So the present work focuses on the thermal model based on a three anisotropic layers. The active chips are assumed as planar or volumetric heat sources. These assumptions are compared to a state-of-art numerical model which details all PWB layers. As expected the accuracy is depending of the geometrical representation of the source. Thus, the planar-source model is within ±16% of relative error with the numerical results when volumetric-source model is ±8%. Nevertheless, both source-models demonstrate their high capability to quickly predict the thermal behavior of embedded chips placements. Moreover, the three-dimensional representation of the chip is discussed in terms of computation effort.
{"title":"Three dimensional steady-state temperature prediction of volumetric heating sources embedded into multi-layer electronic board substrate","authors":"B. Rogié, E. Monier-Vinard, N. Nguyen, N. Laraqi, V. Bissuel, O. Daniel","doi":"10.1109/ITHERM.2017.7992528","DOIUrl":"https://doi.org/10.1109/ITHERM.2017.7992528","url":null,"abstract":"Burying active chips into internal layers of a Printed Wiring Board (PWB) allows increasing the density of an electronic board but leads to higher thermal stress inside its structure. To help the designers for analyzing the limits of the in-layer power dissipation, various analytical approaches were investigated. So the present work focuses on the thermal model based on a three anisotropic layers. The active chips are assumed as planar or volumetric heat sources. These assumptions are compared to a state-of-art numerical model which details all PWB layers. As expected the accuracy is depending of the geometrical representation of the source. Thus, the planar-source model is within ±16% of relative error with the numerical results when volumetric-source model is ±8%. Nevertheless, both source-models demonstrate their high capability to quickly predict the thermal behavior of embedded chips placements. Moreover, the three-dimensional representation of the chip is discussed in terms of computation effort.","PeriodicalId":387542,"journal":{"name":"2017 16th IEEE Intersociety Conference on Thermal and Thermomechanical Phenomena in Electronic Systems (ITherm)","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2017-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"116828171","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 : 2017-05-01DOI: 10.1109/ITHERM.2017.7992610
S. Chigullapalli, Jared A. Shipman
IoT is the new wave of technology that is rapidly rising from embedded system space into futuristic applications such as smart cities, smart cars and overall smart living. Thermal mechanical design of these devices for extreme environments becomes extremely challenging and the effect of the sun & climate can no longer be ignored. This paper describes the quantitative effect of solar radiation on the junction temperature of silicon in IoT devices and qualitatively describes the effect on continuous operation over a year in Phoenix outdoor environment.
{"title":"Thermal & solar radiation considerations for simulation & design of IoT gateways for outdoor applications","authors":"S. Chigullapalli, Jared A. Shipman","doi":"10.1109/ITHERM.2017.7992610","DOIUrl":"https://doi.org/10.1109/ITHERM.2017.7992610","url":null,"abstract":"IoT is the new wave of technology that is rapidly rising from embedded system space into futuristic applications such as smart cities, smart cars and overall smart living. Thermal mechanical design of these devices for extreme environments becomes extremely challenging and the effect of the sun & climate can no longer be ignored. This paper describes the quantitative effect of solar radiation on the junction temperature of silicon in IoT devices and qualitatively describes the effect on continuous operation over a year in Phoenix outdoor environment.","PeriodicalId":387542,"journal":{"name":"2017 16th IEEE Intersociety Conference on Thermal and Thermomechanical Phenomena in Electronic Systems (ITherm)","volume":"30 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2017-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"114585262","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 : 2017-05-01DOI: 10.1109/ITHERM.2017.7992572
Raymond Lloyd, Jer Hayes, M. Rebow, Brian Norton
Data centres account for approx. 1.3% of the world's electricity consumption, of which up to 50% of that power is dedicated to keeping the actual equipment cool. This represents a huge opportunity to reduce data centre energy consumption by tackling the cooling system operations with a focus on thermal management. This work presents a novel Data Centre Air Flow Model (DCAM) for temperature prediction of server inlet temperatures. The model is a physics-based model under-pinned by turbulent jet theory allowing a reduction in the solution domain size by using only local boundary conditions in front of the servers. Current physics-based modeling approaches require a solution domain of the entire data centre room which is expensive in terms of computation even if a small change occurs in a localized area. By limiting the solution domain and boundary conditions to a local level, the model focuses on the airflow mixing that affects temperatures while also simplifying the related computations. The DCAM model does not have the usual complexities of numerical computations, dependencies on computational grid size, meshing or the need to solve a full domain solution. The input boundary conditions required for the model can be supplied by the Building Management System (BMS), Power Distribution Units (PDU), sensors, or output from other modeling environments that only need updating when significant changes occur. Preliminary results validated on a real world data centre yield an overall prediction error of 1.2° C RMSE. The model can perform in real-time, giving way to applications for real-time monitoring, as input to optimize control of air conditioning units, and can complement sensor networks.
{"title":"A data centre air flow model for predicting computer server inlet temperatures","authors":"Raymond Lloyd, Jer Hayes, M. Rebow, Brian Norton","doi":"10.1109/ITHERM.2017.7992572","DOIUrl":"https://doi.org/10.1109/ITHERM.2017.7992572","url":null,"abstract":"Data centres account for approx. 1.3% of the world's electricity consumption, of which up to 50% of that power is dedicated to keeping the actual equipment cool. This represents a huge opportunity to reduce data centre energy consumption by tackling the cooling system operations with a focus on thermal management. This work presents a novel Data Centre Air Flow Model (DCAM) for temperature prediction of server inlet temperatures. The model is a physics-based model under-pinned by turbulent jet theory allowing a reduction in the solution domain size by using only local boundary conditions in front of the servers. Current physics-based modeling approaches require a solution domain of the entire data centre room which is expensive in terms of computation even if a small change occurs in a localized area. By limiting the solution domain and boundary conditions to a local level, the model focuses on the airflow mixing that affects temperatures while also simplifying the related computations. The DCAM model does not have the usual complexities of numerical computations, dependencies on computational grid size, meshing or the need to solve a full domain solution. The input boundary conditions required for the model can be supplied by the Building Management System (BMS), Power Distribution Units (PDU), sensors, or output from other modeling environments that only need updating when significant changes occur. Preliminary results validated on a real world data centre yield an overall prediction error of 1.2° C RMSE. The model can perform in real-time, giving way to applications for real-time monitoring, as input to optimize control of air conditioning units, and can complement sensor networks.","PeriodicalId":387542,"journal":{"name":"2017 16th IEEE Intersociety Conference on Thermal and Thermomechanical Phenomena in Electronic Systems (ITherm)","volume":"28 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2017-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"133519919","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 : 2017-05-01DOI: 10.1109/ITHERM.2017.7992533
Tuhin Sinha, J. Zitz
This research effort is geared towards establishing a robust virtual-qualification methodology for thermal performance of flip-chip packages. In the experimental analysis presented here, test vehicles were designed and tested for degradation in the module-level thermal interface material under high temperature storage (at 100C, 125C and 150C) exposure and deep thermal cycling (−40C/+125C) conditions. The experiments conducted in this study will encompass a wide range of thermo-mechanical conditions that not only explore known JEDEC variables but also provide unique insights into understanding the effects of indirect thermal degradation drivers such as package assembly loads and chip-junction temperature variations during thermal power inputs during readouts.
{"title":"A systematic experimental investigation of thermal degradation mechanisms in lidded flip-chip packages: Effects of thermal aging and cyclic loading","authors":"Tuhin Sinha, J. Zitz","doi":"10.1109/ITHERM.2017.7992533","DOIUrl":"https://doi.org/10.1109/ITHERM.2017.7992533","url":null,"abstract":"This research effort is geared towards establishing a robust virtual-qualification methodology for thermal performance of flip-chip packages. In the experimental analysis presented here, test vehicles were designed and tested for degradation in the module-level thermal interface material under high temperature storage (at 100C, 125C and 150C) exposure and deep thermal cycling (−40C/+125C) conditions. The experiments conducted in this study will encompass a wide range of thermo-mechanical conditions that not only explore known JEDEC variables but also provide unique insights into understanding the effects of indirect thermal degradation drivers such as package assembly loads and chip-junction temperature variations during thermal power inputs during readouts.","PeriodicalId":387542,"journal":{"name":"2017 16th IEEE Intersociety Conference on Thermal and Thermomechanical Phenomena in Electronic Systems (ITherm)","volume":"35 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2017-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"121901183","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 : 2017-05-01DOI: 10.1109/ITHERM.2017.7992482
Sivasubramani Krishnaswamy, Palkesh Jain, M. Saeidi, Aniket Kulkarni, Ankit Adhiya, J. Harvest
Power saving techniques and associated thermal management are inevitable for present day smartphones. Smartphones employ thermal feedback (temperature at key locations) based dynamic power management strategies to maintain the system temperature in the desired range. It is challenging to simulate the thermal behavior of such a system as running a computational fluid dynamics system with control logic consumes significant time and computation resources. An efficient transient thermal model for smartphone simulation based on Linear Time Invariant (LTI) system is proposed in this paper. State space model developed based on LTI system can be used for transient thermal simulations with similar accuracy as full 3D transient CFD model but a significantly faster run time. The model generation process starts with computation fluid dynamics (CFD) results of a smartphone model. A state model is created which is very efficient and runs orders of magnitude faster. Extracted state space model can be used to check different variations of power control logics for a given smart phone design without the need to perform Full CFD analysis. In this paper, case study has been conducted to compare results from state space model with full CFD model for specific control logic.
{"title":"Fast and accurate thermal analysis of smartphone with dynamic power management using reduced order modeling","authors":"Sivasubramani Krishnaswamy, Palkesh Jain, M. Saeidi, Aniket Kulkarni, Ankit Adhiya, J. Harvest","doi":"10.1109/ITHERM.2017.7992482","DOIUrl":"https://doi.org/10.1109/ITHERM.2017.7992482","url":null,"abstract":"Power saving techniques and associated thermal management are inevitable for present day smartphones. Smartphones employ thermal feedback (temperature at key locations) based dynamic power management strategies to maintain the system temperature in the desired range. It is challenging to simulate the thermal behavior of such a system as running a computational fluid dynamics system with control logic consumes significant time and computation resources. An efficient transient thermal model for smartphone simulation based on Linear Time Invariant (LTI) system is proposed in this paper. State space model developed based on LTI system can be used for transient thermal simulations with similar accuracy as full 3D transient CFD model but a significantly faster run time. The model generation process starts with computation fluid dynamics (CFD) results of a smartphone model. A state model is created which is very efficient and runs orders of magnitude faster. Extracted state space model can be used to check different variations of power control logics for a given smart phone design without the need to perform Full CFD analysis. In this paper, case study has been conducted to compare results from state space model with full CFD model for specific control logic.","PeriodicalId":387542,"journal":{"name":"2017 16th IEEE Intersociety Conference on Thermal and Thermomechanical Phenomena in Electronic Systems (ITherm)","volume":"7 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2017-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"130322922","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 : 2017-05-01DOI: 10.1109/ITHERM.2017.7992550
S. Kang, J. Visser, S. N. Oskouie
This paper reports on the predictive capabilities of a new commercial software called aCool with a more sophisticated representation of heat pipes that accounts for both the thermal resistance and the heat transport limitations in CFD models of thermal solutions such as heat sinks. Rather than rely solely on the theoretical heat transport capabilities of heat pipes, the properties of the heat pipes in the software are based on experimentally measured characteristics of real production copper-water heat pipes including real world defects in the wick, effects of gravity, changes in wick types along the length of the heat pipe, and changes in heat transport limits with temperature. The aCool representation of heat pipes is validated against our experimental measurements for three test case studies. The test cases include heat transport through heat pipes in a stand-alone configuration, heat spreading in the base of a heat sink for insulated-gate bipolar transistors (IGBT) cooling, and base spreading in a heat sink with an uneven air flow distribution through the fins.
{"title":"Heat pipe models in thermal design software including realistic representation of thermal resistance and heat transport limit","authors":"S. Kang, J. Visser, S. N. Oskouie","doi":"10.1109/ITHERM.2017.7992550","DOIUrl":"https://doi.org/10.1109/ITHERM.2017.7992550","url":null,"abstract":"This paper reports on the predictive capabilities of a new commercial software called aCool with a more sophisticated representation of heat pipes that accounts for both the thermal resistance and the heat transport limitations in CFD models of thermal solutions such as heat sinks. Rather than rely solely on the theoretical heat transport capabilities of heat pipes, the properties of the heat pipes in the software are based on experimentally measured characteristics of real production copper-water heat pipes including real world defects in the wick, effects of gravity, changes in wick types along the length of the heat pipe, and changes in heat transport limits with temperature. The aCool representation of heat pipes is validated against our experimental measurements for three test case studies. The test cases include heat transport through heat pipes in a stand-alone configuration, heat spreading in the base of a heat sink for insulated-gate bipolar transistors (IGBT) cooling, and base spreading in a heat sink with an uneven air flow distribution through the fins.","PeriodicalId":387542,"journal":{"name":"2017 16th IEEE Intersociety Conference on Thermal and Thermomechanical Phenomena in Electronic Systems (ITherm)","volume":"58 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2017-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129124604","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 : 2017-05-01DOI: 10.1109/ITHERM.2017.7992625
M. Alam, J. Suhling, P. Lall
The mechanical behavior of lead free solders is highly dependent on the testing temperature. Previous investigations on mechanical characterization of conventional and doped lead free SAC solders have mainly emphasized stress-strain and creep testing at temperatures from 25 to 125 °C. However, solders are exposed to very high temperatures from 125–200 °C in several harsh environment applications including well boring, geothermal energy, and aerospace engines. In the current work, we have extended our previous studies to explore mechanical properties for SAC305, SAC_Q, SAC_R, and Innolot solders at temperatures from 125–200 °C at a strain rate of 0.001 (sec−1). The Anand constitutive model with parameters measured previously using test data from 25–125 has been shown to fit the high temperature stress-strain curves reasonably well. In addition, high temperature creep behavior of SAC305 was explored. Finally, the high temperature tensile properties of the above-mentioned solders have been compared. Our results show a significant degradation of mechanical properties of lead-free solders at higher temperatures. Also, a noteworthy increase in the secondary creep strain rate has been observed. Comparison of the results for different solders has shown that the addition of dopants (e.g. Bi, Ni, and Sb) in the traditional SAC alloys improve their properties significantly.
{"title":"High temperature tensile and creep behavior of lead free solders","authors":"M. Alam, J. Suhling, P. Lall","doi":"10.1109/ITHERM.2017.7992625","DOIUrl":"https://doi.org/10.1109/ITHERM.2017.7992625","url":null,"abstract":"The mechanical behavior of lead free solders is highly dependent on the testing temperature. Previous investigations on mechanical characterization of conventional and doped lead free SAC solders have mainly emphasized stress-strain and creep testing at temperatures from 25 to 125 °C. However, solders are exposed to very high temperatures from 125–200 °C in several harsh environment applications including well boring, geothermal energy, and aerospace engines. In the current work, we have extended our previous studies to explore mechanical properties for SAC305, SAC_Q, SAC_R, and Innolot solders at temperatures from 125–200 °C at a strain rate of 0.001 (sec−1). The Anand constitutive model with parameters measured previously using test data from 25–125 has been shown to fit the high temperature stress-strain curves reasonably well. In addition, high temperature creep behavior of SAC305 was explored. Finally, the high temperature tensile properties of the above-mentioned solders have been compared. Our results show a significant degradation of mechanical properties of lead-free solders at higher temperatures. Also, a noteworthy increase in the secondary creep strain rate has been observed. Comparison of the results for different solders has shown that the addition of dopants (e.g. Bi, Ni, and Sb) in the traditional SAC alloys improve their properties significantly.","PeriodicalId":387542,"journal":{"name":"2017 16th IEEE Intersociety Conference on Thermal and Thermomechanical Phenomena in Electronic Systems (ITherm)","volume":"138 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2017-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129967063","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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