Pub Date : 2010-05-18DOI: 10.1109/TCAPT.2010.2045378
M. Koganemaru, T. Ikeda, N. Miyazaki, H. Tomokage
Stress-induced shifts of the direct current characteristics on n-type metal oxide semiconductor field effect transistors (nMOSFETs) were investigated experimentally. The stress sensitivities of nMOSFET characteristics were measured by the 4-point bending method, and the gate-length dependence of transconductance shifts caused by uniaxial stress was evaluated. As a result, it is shown that the gate-length dependence of transconductance shifts is attributed to parasitic resistance of the nMOSFETs. Also, this paper verified the electron-mobility model proposed in the previous study that includes stress effects in comparison with the experimental results. As a result, several improvements for the electron-mobility model are proposed in this paper. We describe the change of the conduction-band energy induced by the shear deformation of silicon. The shear deformation with a uniaxial stress along the direction of silicon should be considered in the change of the conduction-band energy.
{"title":"Experimental Study of Uniaxial-Stress Effects on DC Characteristics of nMOSFETs","authors":"M. Koganemaru, T. Ikeda, N. Miyazaki, H. Tomokage","doi":"10.1109/TCAPT.2010.2045378","DOIUrl":"https://doi.org/10.1109/TCAPT.2010.2045378","url":null,"abstract":"Stress-induced shifts of the direct current characteristics on n-type metal oxide semiconductor field effect transistors (nMOSFETs) were investigated experimentally. The stress sensitivities of nMOSFET characteristics were measured by the 4-point bending method, and the gate-length dependence of transconductance shifts caused by uniaxial stress was evaluated. As a result, it is shown that the gate-length dependence of transconductance shifts is attributed to parasitic resistance of the nMOSFETs. Also, this paper verified the electron-mobility model proposed in the previous study that includes stress effects in comparison with the experimental results. As a result, several improvements for the electron-mobility model are proposed in this paper. We describe the change of the conduction-band energy induced by the shear deformation of silicon. The shear deformation with a uniaxial stress along the direction of silicon should be considered in the change of the conduction-band energy.","PeriodicalId":55013,"journal":{"name":"IEEE Transactions on Components and Packaging Technologies","volume":"33 1","pages":"278-286"},"PeriodicalIF":0.0,"publicationDate":"2010-05-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1109/TCAPT.2010.2045378","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"62520169","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 : 2010-05-18DOI: 10.1109/TCAPT.2010.2046326
T. Świa̧tczak, B. Vermeersch, G. De Mey, B. Więcek, J. Banaszczyk, M. Felczak
In this paper, it is outlined how thermal AC measurements can be carried out on a resistor deposited on an electronic substrate. The AC approach enables us to limit ourselves to phase measurements which can be carried out with a much higher precision than amplitude measurements. It will also be demonstrated how the phase measurements at a well-chosen frequency can be used to measure the heat transfer coefficient.
{"title":"Evaluation of the Heat Transfer Coefficient in Microcircuits From the Frequency Analysis of the Thermal Transient Response","authors":"T. Świa̧tczak, B. Vermeersch, G. De Mey, B. Więcek, J. Banaszczyk, M. Felczak","doi":"10.1109/TCAPT.2010.2046326","DOIUrl":"https://doi.org/10.1109/TCAPT.2010.2046326","url":null,"abstract":"In this paper, it is outlined how thermal AC measurements can be carried out on a resistor deposited on an electronic substrate. The AC approach enables us to limit ourselves to phase measurements which can be carried out with a much higher precision than amplitude measurements. It will also be demonstrated how the phase measurements at a well-chosen frequency can be used to measure the heat transfer coefficient.","PeriodicalId":55013,"journal":{"name":"IEEE Transactions on Components and Packaging Technologies","volume":"176 1","pages":"260-266"},"PeriodicalIF":0.0,"publicationDate":"2010-05-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1109/TCAPT.2010.2046326","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"62520238","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 : 2010-05-10DOI: 10.1109/TCAPT.2010.2042717
Y. Liu, Yuanxing Zhang, L. Liang
This paper proposes a new prediction method for electromigration (EM) induced void generation of solder bumps in a wafer level chip scale package. The methodology is developed based on discretized weighted residual method in a user-defined finite element analysis framework to solve the local ME governing equation with the variable of atomic concentration. The local solution of atomic concentration is incorporated in the multiphysics environment for electrical, thermal and stress in both sub-model and global model. The new method takes the advantage of solving the variable of atomic density, it avoids directly solving the divergences of the atomic flux, which includes the atomic density gradient items and is very hard and challenging to get the solution by traditional method. Comparison of the atomic density distributions with and without considering the atomic density gradient for representive nodes is investigated. The simulation results for voids and time to failure (TTF) are discussed and correlated with previous test results. Finally, the analysis of the impact of under ball metallurgy and solder bump geometry on the void generation and TTF is presented.
{"title":"Prediction of Electromigration Induced Voids and Time to Failure for Solder Joint of a Wafer Level Chip Scale Package","authors":"Y. Liu, Yuanxing Zhang, L. Liang","doi":"10.1109/TCAPT.2010.2042717","DOIUrl":"https://doi.org/10.1109/TCAPT.2010.2042717","url":null,"abstract":"This paper proposes a new prediction method for electromigration (EM) induced void generation of solder bumps in a wafer level chip scale package. The methodology is developed based on discretized weighted residual method in a user-defined finite element analysis framework to solve the local ME governing equation with the variable of atomic concentration. The local solution of atomic concentration is incorporated in the multiphysics environment for electrical, thermal and stress in both sub-model and global model. The new method takes the advantage of solving the variable of atomic density, it avoids directly solving the divergences of the atomic flux, which includes the atomic density gradient items and is very hard and challenging to get the solution by traditional method. Comparison of the atomic density distributions with and without considering the atomic density gradient for representive nodes is investigated. The simulation results for voids and time to failure (TTF) are discussed and correlated with previous test results. Finally, the analysis of the impact of under ball metallurgy and solder bump geometry on the void generation and TTF is presented.","PeriodicalId":55013,"journal":{"name":"IEEE Transactions on Components and Packaging Technologies","volume":"33 1","pages":"544-552"},"PeriodicalIF":0.0,"publicationDate":"2010-05-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1109/TCAPT.2010.2042717","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"62519924","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 : 2010-05-03DOI: 10.1109/TCAPT.2010.2040737
S. Karajgikar, Smitha M. N. Rao, J. Sin, D. Agonafer, J. Chiao, D. Popa, H. Stephanou
This paper describes the modeling for a packaged in-plane micropump developed at the Automation and Robotics Research Institute, The University of Texas, Arlington, TX. Amongst the family of micro-electro-mechanical system (MEMS) devices, thermal actuators are important owing to their capability to deliver a large force and displacement. Due to fabrication and cost-savings advantages, these actuators are now commonly used in several applications, such as optical-communication switches, micro-assembly, and micro-positioners. The proposed micropump design is based on these actuators fabricated by a one-step deep reactive ion etching process and packaged for protection and appropriate thermal dissipation. In the current ongoing research, the thermal actuator forms an integral part of an in-plane micropump. The flow rate is controlled by the variations in actuator displacement and corresponding force generated. Flow rates of several micro-liters per minute can be obtained making this pump suitable for drug delivery applications. Actuation is caused by application of voltage and resulting joule heating effect of the MEMS chevron beams. This results in displacement of the beams (actuator) which is proportional to the difference in temperature. Some of the parameters governing the displacement include the applied voltage, resistivity of the device, substrate thickness, and air gap between the device and the substrate. In this paper, the proposed micro-pump was analyzed for its thermal performance, pumping force, and the corresponding flow rate. The analysis was performed at device, die, and package levels. Thermal analysis showed that there exists a linear relationship between the applied voltage and the resulting temperature. Maximum temperature was always noted at the center of the chevron beams. The analysis also showed that force generated by the thermal actuators mainly depends on the average temperature of the chevron beams. Maximum force of 3.73 mN was noted for the packaged micropump at 23 V. This corresponded to an average beam temperature of 453°C and a flow rate of 11.2 μl/min. Performance assessment of the pump showed that for every 5 kPa increase in backpressure, flow rate reduced approximately by 5%.
{"title":"Electro-Thermal Analysis of In-Plane Micropump","authors":"S. Karajgikar, Smitha M. N. Rao, J. Sin, D. Agonafer, J. Chiao, D. Popa, H. Stephanou","doi":"10.1109/TCAPT.2010.2040737","DOIUrl":"https://doi.org/10.1109/TCAPT.2010.2040737","url":null,"abstract":"This paper describes the modeling for a packaged in-plane micropump developed at the Automation and Robotics Research Institute, The University of Texas, Arlington, TX. Amongst the family of micro-electro-mechanical system (MEMS) devices, thermal actuators are important owing to their capability to deliver a large force and displacement. Due to fabrication and cost-savings advantages, these actuators are now commonly used in several applications, such as optical-communication switches, micro-assembly, and micro-positioners. The proposed micropump design is based on these actuators fabricated by a one-step deep reactive ion etching process and packaged for protection and appropriate thermal dissipation. In the current ongoing research, the thermal actuator forms an integral part of an in-plane micropump. The flow rate is controlled by the variations in actuator displacement and corresponding force generated. Flow rates of several micro-liters per minute can be obtained making this pump suitable for drug delivery applications. Actuation is caused by application of voltage and resulting joule heating effect of the MEMS chevron beams. This results in displacement of the beams (actuator) which is proportional to the difference in temperature. Some of the parameters governing the displacement include the applied voltage, resistivity of the device, substrate thickness, and air gap between the device and the substrate. In this paper, the proposed micro-pump was analyzed for its thermal performance, pumping force, and the corresponding flow rate. The analysis was performed at device, die, and package levels. Thermal analysis showed that there exists a linear relationship between the applied voltage and the resulting temperature. Maximum temperature was always noted at the center of the chevron beams. The analysis also showed that force generated by the thermal actuators mainly depends on the average temperature of the chevron beams. Maximum force of 3.73 mN was noted for the packaged micropump at 23 V. This corresponded to an average beam temperature of 453°C and a flow rate of 11.2 μl/min. Performance assessment of the pump showed that for every 5 kPa increase in backpressure, flow rate reduced approximately by 5%.","PeriodicalId":55013,"journal":{"name":"IEEE Transactions on Components and Packaging Technologies","volume":"33 1","pages":"329-339"},"PeriodicalIF":0.0,"publicationDate":"2010-05-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1109/TCAPT.2010.2040737","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"62520129","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 : 2010-05-03DOI: 10.1109/TCAPT.2010.2040069
Zhou Jian-hui, Yang Chun-xin
The procedure of the parametric design and numerical simulation is developed to enhance greatly fan design efficiency, which can generate high quality hexahedral mesh automatically. The numerical simulation can be performed automatically and the aerodynamic performance of the fan can be characterized without using any other tools. The developed procedure can be employed to the optimization design of the fan. Based on the procedure of the parametric design and numerical simulation, the influences of various design parameters on the aerodynamic performance of the fan are investigated deeply. Such influences can provide physical insight into the flow characteristics of the fan. The multiparameter constrained optimization procedure based on the combination algorithms of design of experiments, response surface models, genetic algorithm, and mixed integer optimization, is carried out aiming at the fan to maximize its coefficient of flow rate over the operating range rather than at a single operating point with parallel computational fluid dynamics. Results show that the aerodynamic average flow rate coefficient of the optimal fan is increased by 14.5% compared to the initially designed fan. This paper demonstrates the potential of the proposed procedure to be applied widely in industry for the purpose of improving work efficiency among engineers.
{"title":"Parametric Design and Numerical Simulation of the Axial-Flow Fan for Electronic Devices","authors":"Zhou Jian-hui, Yang Chun-xin","doi":"10.1109/TCAPT.2010.2040069","DOIUrl":"https://doi.org/10.1109/TCAPT.2010.2040069","url":null,"abstract":"The procedure of the parametric design and numerical simulation is developed to enhance greatly fan design efficiency, which can generate high quality hexahedral mesh automatically. The numerical simulation can be performed automatically and the aerodynamic performance of the fan can be characterized without using any other tools. The developed procedure can be employed to the optimization design of the fan. Based on the procedure of the parametric design and numerical simulation, the influences of various design parameters on the aerodynamic performance of the fan are investigated deeply. Such influences can provide physical insight into the flow characteristics of the fan. The multiparameter constrained optimization procedure based on the combination algorithms of design of experiments, response surface models, genetic algorithm, and mixed integer optimization, is carried out aiming at the fan to maximize its coefficient of flow rate over the operating range rather than at a single operating point with parallel computational fluid dynamics. Results show that the aerodynamic average flow rate coefficient of the optimal fan is increased by 14.5% compared to the initially designed fan. This paper demonstrates the potential of the proposed procedure to be applied widely in industry for the purpose of improving work efficiency among engineers.","PeriodicalId":55013,"journal":{"name":"IEEE Transactions on Components and Packaging Technologies","volume":"33 1","pages":"287-298"},"PeriodicalIF":0.0,"publicationDate":"2010-05-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1109/TCAPT.2010.2040069","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"62520051","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 : 2010-05-03DOI: 10.1109/TCAPT.2010.2041929
W. Wits, T. Vaneker
A novel, integrated approach in thermal management of electronic products, based on two-phase cooling, is presented. A flat miniature heat pipe, integrated inside the laminated structure of a printed circuit board (PCB) has been developed, based on mainstream PCB fabrication processes. Hot spots on the PCB, caused by heat dissipating components, can be cooled with relatively small temperature gradients across the board. An analytical model is presented to predict the behavior of the embedded heat pipe for various geometries, orientations, and operating temperatures. Experimental verification has shown successful heat pipe operation. The heat pipe exhibited a measured equivalent thermal conductivity more than seven times higher than solid copper. Low-thermal resistance values establish this concept as a promising thermal management solution for future electronic products. As mainstream manufacturing techniques are applied, thin PCBs with integrated cooling support can be produced at low-cost.
{"title":"Integrated Design and Manufacturing of Flat Miniature Heat Pipes Using Printed Circuit Board Technology","authors":"W. Wits, T. Vaneker","doi":"10.1109/TCAPT.2010.2041929","DOIUrl":"https://doi.org/10.1109/TCAPT.2010.2041929","url":null,"abstract":"A novel, integrated approach in thermal management of electronic products, based on two-phase cooling, is presented. A flat miniature heat pipe, integrated inside the laminated structure of a printed circuit board (PCB) has been developed, based on mainstream PCB fabrication processes. Hot spots on the PCB, caused by heat dissipating components, can be cooled with relatively small temperature gradients across the board. An analytical model is presented to predict the behavior of the embedded heat pipe for various geometries, orientations, and operating temperatures. Experimental verification has shown successful heat pipe operation. The heat pipe exhibited a measured equivalent thermal conductivity more than seven times higher than solid copper. Low-thermal resistance values establish this concept as a promising thermal management solution for future electronic products. As mainstream manufacturing techniques are applied, thin PCBs with integrated cooling support can be produced at low-cost.","PeriodicalId":55013,"journal":{"name":"IEEE Transactions on Components and Packaging Technologies","volume":"33 1","pages":"398-408"},"PeriodicalIF":0.0,"publicationDate":"2010-05-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1109/TCAPT.2010.2041929","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"62519779","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 : 2010-05-03DOI: 10.1109/TCAPT.2010.2044412
Kai-Shing Yang, Jhih-Hao Jhong, Yur-Tsai Lin, K. Chien, Chi-Chuan Wang
This paper examines the airside performance of heat sinks having fin patterns of delta, semi-circular vortex generators, plain fin and their combinations. Test results indicate that the heat transfer performance is strongly related to the developing and fully developed flow characteristics. The augmentations via vortex generator are relatively effective when the flow is in the developing region whereas they become quite less effective in the fully developed region. This is especially pronounced when the fin pitch is small or operated at a lower frontal velocity. Actually, the plain fin geometry outperforms most of the fin patterns at the fully developed region. This is because a close spacing prevented the formation of vortex, and the presence of interrupted surface may also suffer from the degradation by constriction of conduction path. The results suggest that the vortex generators operated at a higher frontal velocity and at a larger fin pitch are more beneficial than that of plain fin geometry. The semi-circular vortex generator possesses the highest heat transfer coefficients and pressure drops at developing region, suggesting the mechanism of blockage of conduction path cannot be overlooked. The performance of dense or loose vortex generator is moderate either in a developing or fully developed region. In association with the VG-1 criteria (same pumping power and same heat transfer capacity), the asymmetric design (VG+plain) reveals the best results. The design could reduce 31.1% required heat dissipation area at a frontal velocity of 5 m/s within a developing region. Yet, it is still applicable in a fully developed region with an area reduction of 1.8-11.5% at a frontal velocity 3-5 m/s.
{"title":"On the Heat Transfer Characteristics of Heat Sinks: With and Without Vortex Generators","authors":"Kai-Shing Yang, Jhih-Hao Jhong, Yur-Tsai Lin, K. Chien, Chi-Chuan Wang","doi":"10.1109/TCAPT.2010.2044412","DOIUrl":"https://doi.org/10.1109/TCAPT.2010.2044412","url":null,"abstract":"This paper examines the airside performance of heat sinks having fin patterns of delta, semi-circular vortex generators, plain fin and their combinations. Test results indicate that the heat transfer performance is strongly related to the developing and fully developed flow characteristics. The augmentations via vortex generator are relatively effective when the flow is in the developing region whereas they become quite less effective in the fully developed region. This is especially pronounced when the fin pitch is small or operated at a lower frontal velocity. Actually, the plain fin geometry outperforms most of the fin patterns at the fully developed region. This is because a close spacing prevented the formation of vortex, and the presence of interrupted surface may also suffer from the degradation by constriction of conduction path. The results suggest that the vortex generators operated at a higher frontal velocity and at a larger fin pitch are more beneficial than that of plain fin geometry. The semi-circular vortex generator possesses the highest heat transfer coefficients and pressure drops at developing region, suggesting the mechanism of blockage of conduction path cannot be overlooked. The performance of dense or loose vortex generator is moderate either in a developing or fully developed region. In association with the VG-1 criteria (same pumping power and same heat transfer capacity), the asymmetric design (VG+plain) reveals the best results. The design could reduce 31.1% required heat dissipation area at a frontal velocity of 5 m/s within a developing region. Yet, it is still applicable in a fully developed region with an area reduction of 1.8-11.5% at a frontal velocity 3-5 m/s.","PeriodicalId":55013,"journal":{"name":"IEEE Transactions on Components and Packaging Technologies","volume":"33 1","pages":"391-397"},"PeriodicalIF":0.0,"publicationDate":"2010-05-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1109/TCAPT.2010.2044412","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"62519978","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 : 2010-05-03DOI: 10.1109/TCAPT.2010.2041779
S. Ebbens, D. Hutt, Changqing Liu
The ability of alkanethiol monolayers deposited on copper to prevent surface oxidation has suggested their application as preservatives for fluxless soldering. However, the utility of such coatings for this purpose will critically depend on their ability to continue to preserve the substrate during exposure to elevated temperatures throughout the electronics manufacturing process. Consequently, the aim of this paper is to systematically determine the effect of storage temperature and duration on the ability of alkanethiol coated copper samples to undergo fluxless soldering. Similarly, the effect of pre-heating copper immediately prior to soldering is also investigated. The effect of reducing atmospheric oxygen concentration during storage and soldering is also considered as a potential route to improve the thermal resilience of the coatings. Parallel to ascertaining these industrially relevant performance parameters, a quantitative correlation between surface chemistry and solder wetting is established, and the temperature dependence of the kinetics of surface oxidation through an alkanethiol barrier layer is discussed.
{"title":"The Thermal Stability of Alkanethiol Self-Assembled Monolayers on Copper for Fluxless Soldering Applications","authors":"S. Ebbens, D. Hutt, Changqing Liu","doi":"10.1109/TCAPT.2010.2041779","DOIUrl":"https://doi.org/10.1109/TCAPT.2010.2041779","url":null,"abstract":"The ability of alkanethiol monolayers deposited on copper to prevent surface oxidation has suggested their application as preservatives for fluxless soldering. However, the utility of such coatings for this purpose will critically depend on their ability to continue to preserve the substrate during exposure to elevated temperatures throughout the electronics manufacturing process. Consequently, the aim of this paper is to systematically determine the effect of storage temperature and duration on the ability of alkanethiol coated copper samples to undergo fluxless soldering. Similarly, the effect of pre-heating copper immediately prior to soldering is also investigated. The effect of reducing atmospheric oxygen concentration during storage and soldering is also considered as a potential route to improve the thermal resilience of the coatings. Parallel to ascertaining these industrially relevant performance parameters, a quantitative correlation between surface chemistry and solder wetting is established, and the temperature dependence of the kinetics of surface oxidation through an alkanethiol barrier layer is discussed.","PeriodicalId":55013,"journal":{"name":"IEEE Transactions on Components and Packaging Technologies","volume":"33 1","pages":"251-259"},"PeriodicalIF":0.0,"publicationDate":"2010-05-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1109/TCAPT.2010.2041779","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"62520223","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 : 2010-04-26DOI: 10.1109/TCAPT.2009.2039794
M. Dogruoz, M. Arik
Seamless advancements in the electronics industry lead to high heat fluxes from very limited thermal real estates. Use of natural convection air cooling is of interest to meet some of the low flux cooling needs, while active cooling techniques via liquid or forced convection are the methods of choice. In natural convection heat transfer applications, the components used for cooling may represent a significant portion of the overall weight of the system. Consequently, advanced materials are of interest in such applications, as they may substantially reduce the total size and weight of the system. Many of these advanced materials have anisotropic thermophysical properties, hence the control of thermal conductivity is crucial. This paper is motivated to address the lack of understanding of the use of anisotropic advanced materials in natural convection environments. Numerical simulations are carried out to test the performance of heat sinks made of such materials and comparisons are made with the heat sinks of traditional engineering materials under the same conditions. The results demonstrate that the total weight of the system may be reduced drastically with the use of advanced materials relative to the most commonly used heat sink materials at the same thermal performance. A figure of merit (FOM) is proposed to compare the thermal performance of different heat sinks. Total resistance, conduction and convection resistances, and performance-related FOM values for each heat sink are presented. It is shown that the conduction thermal resistance is dominant at lower fin thicknesses for sparse heat sinks while it is negligible for dense heat sinks. Pyrolytic graphite-based heat sinks demonstrate the best thermal performance, while carbon-foam heat sinks produce the highest FOM values due to the material's low density.
{"title":"On the Conduction and Convection Heat Transfer From Lightweight Advanced Heat Sinks","authors":"M. Dogruoz, M. Arik","doi":"10.1109/TCAPT.2009.2039794","DOIUrl":"https://doi.org/10.1109/TCAPT.2009.2039794","url":null,"abstract":"Seamless advancements in the electronics industry lead to high heat fluxes from very limited thermal real estates. Use of natural convection air cooling is of interest to meet some of the low flux cooling needs, while active cooling techniques via liquid or forced convection are the methods of choice. In natural convection heat transfer applications, the components used for cooling may represent a significant portion of the overall weight of the system. Consequently, advanced materials are of interest in such applications, as they may substantially reduce the total size and weight of the system. Many of these advanced materials have anisotropic thermophysical properties, hence the control of thermal conductivity is crucial. This paper is motivated to address the lack of understanding of the use of anisotropic advanced materials in natural convection environments. Numerical simulations are carried out to test the performance of heat sinks made of such materials and comparisons are made with the heat sinks of traditional engineering materials under the same conditions. The results demonstrate that the total weight of the system may be reduced drastically with the use of advanced materials relative to the most commonly used heat sink materials at the same thermal performance. A figure of merit (FOM) is proposed to compare the thermal performance of different heat sinks. Total resistance, conduction and convection resistances, and performance-related FOM values for each heat sink are presented. It is shown that the conduction thermal resistance is dominant at lower fin thicknesses for sparse heat sinks while it is negligible for dense heat sinks. Pyrolytic graphite-based heat sinks demonstrate the best thermal performance, while carbon-foam heat sinks produce the highest FOM values due to the material's low density.","PeriodicalId":55013,"journal":{"name":"IEEE Transactions on Components and Packaging Technologies","volume":"33 1","pages":"424-431"},"PeriodicalIF":0.0,"publicationDate":"2010-04-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1109/TCAPT.2009.2039794","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"62519971","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 : 2010-03-25DOI: 10.1109/TCAPT.2010.2042716
M. Chaudhari, B. Puranik, A. Agrawal
A synthetic jet is a zero-net-mass-flux device, which synthesizes stagnant air to form a jet, and is potentially useful for cooling. Due to the inherent suction and ejection processes in a synthetic jet, its utility in a confined enclosure is not obvious. The synthetic jet impingement heat transfer characteristics inside a rectangular duct are studied in this paper. In addition, the effect of cross-flow created using either fans or another synthetic jet on its heat dissipation capability is examined. Experiments are conducted for different jet Reynolds numbers (Re), in the range of 950-4000, at different offset positions of the synthetic jet with respect to a heated block flush mounted on one surface of the duct. The height of the duct is the same (25 mm) for all measurements while the width is varied between 110 mm and 330 mm in order to examine the effect of confinement on the heat transfer coefficient. The change in the width of the duct is found to have a negligible effect on heat transfer. The heat transfer coefficient is found to be more with synthetic jet direct impingement (150 W/m2 · K) than with combined flow (both impingement and cross-flow) (134 W/m2 · K) or with only cross-flow (45 W/m2 · K) in the duct. The offset of the synthetic jet from the center of the heated block is found to drastically reduce the heat transfer. These results are expected to be useful for designing synthetic jet-based cooling solutions.
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