Pub Date : 2002-08-07DOI: 10.1109/ITHERM.2002.1012504
R. Anton, H. Jonsson, B. Palm
Cooling of data centers has emerged as an area of increasing importance in the field of electronics thermal management. As the packaging and power densities are steadily increasing, so will the need for efficient and reliable cooling systems. In this paper, a model of an air conditioning unit is described. The model offers considerable flexibility in terms of the ability to choose between different designs of heat exchangers (evaporators and condensers), and working media, and hence the model offers the possibility to optimize the design. The model is developed using EES (Engineering Equation Solver), a programming environment that provides the thermo-physical properties for the working media used. The heat transfer and pressure drop in the components, are modeled using an integral approach, i.e. the overall behavior of each component is modeled. This approach has been proven to give adequate accuracy.
{"title":"Modeling of air conditioning systems for cooling of data centers","authors":"R. Anton, H. Jonsson, B. Palm","doi":"10.1109/ITHERM.2002.1012504","DOIUrl":"https://doi.org/10.1109/ITHERM.2002.1012504","url":null,"abstract":"Cooling of data centers has emerged as an area of increasing importance in the field of electronics thermal management. As the packaging and power densities are steadily increasing, so will the need for efficient and reliable cooling systems. In this paper, a model of an air conditioning unit is described. The model offers considerable flexibility in terms of the ability to choose between different designs of heat exchangers (evaporators and condensers), and working media, and hence the model offers the possibility to optimize the design. The model is developed using EES (Engineering Equation Solver), a programming environment that provides the thermo-physical properties for the working media used. The heat transfer and pressure drop in the components, are modeled using an integral approach, i.e. the overall behavior of each component is modeled. This approach has been proven to give adequate accuracy.","PeriodicalId":299933,"journal":{"name":"ITherm 2002. Eighth Intersociety Conference on Thermal and Thermomechanical Phenomena in Electronic Systems (Cat. No.02CH37258)","volume":"101 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2002-08-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"126581693","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 : 2002-08-07DOI: 10.1109/ITHERM.2002.1012438
B. Cullimore
Thermal engineers are now commonly responsible for sizing and selecting active cooling components such as fans and heat sinks, and increasingly single and two-phase coolant loops.. Meanwhile, heat transfer and fluid flow design analysis software has matured, growing both in ease of use and in phenomenological modeling prowess. Unfortunately, most software retains a focus on point-design simulations and needs to do a better job of helping thermal engineers not only evaluate designs, but also investigate alternatives and even automate the search for optimal designs. This paper shows how readily available nonlinear programming (NLP) techniques can be successfully applied to automating design synthesis activities, allowing the thermal engineer to approach the problem from a higher level of automation. This paper briefly introduces NLP concepts, and then demonstrates their application both to a simplified fin (extended surface) as well as a more realistic case: a finned heat sink.
{"title":"Nonlinear programming applied to thermal and fluid design optimization","authors":"B. Cullimore","doi":"10.1109/ITHERM.2002.1012438","DOIUrl":"https://doi.org/10.1109/ITHERM.2002.1012438","url":null,"abstract":"Thermal engineers are now commonly responsible for sizing and selecting active cooling components such as fans and heat sinks, and increasingly single and two-phase coolant loops.. Meanwhile, heat transfer and fluid flow design analysis software has matured, growing both in ease of use and in phenomenological modeling prowess. Unfortunately, most software retains a focus on point-design simulations and needs to do a better job of helping thermal engineers not only evaluate designs, but also investigate alternatives and even automate the search for optimal designs. This paper shows how readily available nonlinear programming (NLP) techniques can be successfully applied to automating design synthesis activities, allowing the thermal engineer to approach the problem from a higher level of automation. This paper briefly introduces NLP concepts, and then demonstrates their application both to a simplified fin (extended surface) as well as a more realistic case: a finned heat sink.","PeriodicalId":299933,"journal":{"name":"ITherm 2002. Eighth Intersociety Conference on Thermal and Thermomechanical Phenomena in Electronic Systems (Cat. No.02CH37258)","volume":"44 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2002-08-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"126925098","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 : 2002-08-07DOI: 10.1109/ITHERM.2002.1012561
H. Lu, C. Bailey
Recently, research has been carried out to test a novel bumping method which omits the under bump metallurgy forming process by bonding copper columns directly onto the Al pads of the silicon dies. This bumping method could be adopted to simplify the flip chip manufacturing process, increase the productivity and achieve a higher I/O count. This paper describes an investigation of the solder joint reliability of flip-chips based on this new bumping process. Computer modelling methods are used to predict the shape of solder joints and response of flip chips to thermal cyclic loading. The accumulated plastic strain energy at the comer solder joints is used as the damage indicator. Models with a range of design parameters have been compared for their reliability. The parameters that have been investigated are the copper column height, radius and solder volume. The ranking of the relative importance of these parameters is given. For most of the results presented in the paper, the solder material has been assumed to be the lead-free 96.5Sn3.5Ag alloy but some results for 60Sn40Pb solder joints have also been presented.
{"title":"Computer modelling of the reliability of flip chips with metal column bumping","authors":"H. Lu, C. Bailey","doi":"10.1109/ITHERM.2002.1012561","DOIUrl":"https://doi.org/10.1109/ITHERM.2002.1012561","url":null,"abstract":"Recently, research has been carried out to test a novel bumping method which omits the under bump metallurgy forming process by bonding copper columns directly onto the Al pads of the silicon dies. This bumping method could be adopted to simplify the flip chip manufacturing process, increase the productivity and achieve a higher I/O count. This paper describes an investigation of the solder joint reliability of flip-chips based on this new bumping process. Computer modelling methods are used to predict the shape of solder joints and response of flip chips to thermal cyclic loading. The accumulated plastic strain energy at the comer solder joints is used as the damage indicator. Models with a range of design parameters have been compared for their reliability. The parameters that have been investigated are the copper column height, radius and solder volume. The ranking of the relative importance of these parameters is given. For most of the results presented in the paper, the solder material has been assumed to be the lead-free 96.5Sn3.5Ag alloy but some results for 60Sn40Pb solder joints have also been presented.","PeriodicalId":299933,"journal":{"name":"ITherm 2002. Eighth Intersociety Conference on Thermal and Thermomechanical Phenomena in Electronic Systems (Cat. No.02CH37258)","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2002-08-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"130476606","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 : 2002-08-07DOI: 10.1109/ITHERM.2002.1012559
Q. Yu, H. Kikuchi, S. Ikeda, M. Shiratori, M. Kakino, N. Fujiwara
Clarifies the dynamic behavior of BGA or CSP packaging subjected to an impact loading, and establishes a simple analytical method of impact reliability assessment for solder joints. In order to take dynamic material properties into account, a high deformation speed tension test and a vibration test were carried out to obtain the strain rate dependence of yield stress and Young's modulus of solder materials and PCB. A 3-D analytical model of PCB mounted with a BGA chip was used to simulate the impact behavior of BGA packaging, and explicit-based FEM code LS-DYNA was used to carry out the dynamic analysis. It was found that the impact reliability of solder joints is greatly affected by the falling posture. However, it was found that fine meshing of solder joints causes a rapid augmentation of calculation cost. In this study, the authors proposed a new method of transient response analysis by utilizing implicit-based FEM code NASTRAN to drop the calculation cost of impact study. It was shown that the present method can accurately simulate the dynamic behavior of BGA packaging including the time histories of the deformations and stresses, and it can drop the CPU time to about one tenth of that of LS-DYNA analysis.
{"title":"Dynamic behavior of electronics package and impact reliability of BGA solder joints","authors":"Q. Yu, H. Kikuchi, S. Ikeda, M. Shiratori, M. Kakino, N. Fujiwara","doi":"10.1109/ITHERM.2002.1012559","DOIUrl":"https://doi.org/10.1109/ITHERM.2002.1012559","url":null,"abstract":"Clarifies the dynamic behavior of BGA or CSP packaging subjected to an impact loading, and establishes a simple analytical method of impact reliability assessment for solder joints. In order to take dynamic material properties into account, a high deformation speed tension test and a vibration test were carried out to obtain the strain rate dependence of yield stress and Young's modulus of solder materials and PCB. A 3-D analytical model of PCB mounted with a BGA chip was used to simulate the impact behavior of BGA packaging, and explicit-based FEM code LS-DYNA was used to carry out the dynamic analysis. It was found that the impact reliability of solder joints is greatly affected by the falling posture. However, it was found that fine meshing of solder joints causes a rapid augmentation of calculation cost. In this study, the authors proposed a new method of transient response analysis by utilizing implicit-based FEM code NASTRAN to drop the calculation cost of impact study. It was shown that the present method can accurately simulate the dynamic behavior of BGA packaging including the time histories of the deformations and stresses, and it can drop the CPU time to about one tenth of that of LS-DYNA analysis.","PeriodicalId":299933,"journal":{"name":"ITherm 2002. Eighth Intersociety Conference on Thermal and Thermomechanical Phenomena in Electronic Systems (Cat. No.02CH37258)","volume":"9 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2002-08-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"128000079","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 : 2002-08-07DOI: 10.1109/ITHERM.2002.1012523
A. Minichiello, C. Belady
This paper presents the thermal design methodology used to design a multi-processor enterprise server, the RP8400. The proposed methodology combines well-known analytical and experimental thermal design tools, including heat transfer correlations, Flow Network Modeling (FNM) and Computational Fluid Dynamics (CFD) techniques, and experimental measurements. The key benefit of this methodology is its emphasis on the use of varied design tools, each applied at its optimal point in the product design cycle. Thus, analysis time is greatly reduced, with acceptable sacrifice to accuracy and detail, during the earliest stages of design when the design concept is fluid, new ideas abound, and speed is paramount. Detailed analyses, providing a greater degree of accuracy, are performed in the latter stages of the development cycle when designs are firm, changes are fewer, and optimization/validation is the goal. In this manner, thermal risk is systematically reduced throughout the product design cycle. This paper begins with an overview of the thermal design methodology. Direct application of the methodology to the design of an enterprise server, the RP8400, is discussed. Numerical modeling and empirical results are presented and compared, followed by a discussion of methods for improving thermal design in future products.
{"title":"Thermal design methodology for electronic systems","authors":"A. Minichiello, C. Belady","doi":"10.1109/ITHERM.2002.1012523","DOIUrl":"https://doi.org/10.1109/ITHERM.2002.1012523","url":null,"abstract":"This paper presents the thermal design methodology used to design a multi-processor enterprise server, the RP8400. The proposed methodology combines well-known analytical and experimental thermal design tools, including heat transfer correlations, Flow Network Modeling (FNM) and Computational Fluid Dynamics (CFD) techniques, and experimental measurements. The key benefit of this methodology is its emphasis on the use of varied design tools, each applied at its optimal point in the product design cycle. Thus, analysis time is greatly reduced, with acceptable sacrifice to accuracy and detail, during the earliest stages of design when the design concept is fluid, new ideas abound, and speed is paramount. Detailed analyses, providing a greater degree of accuracy, are performed in the latter stages of the development cycle when designs are firm, changes are fewer, and optimization/validation is the goal. In this manner, thermal risk is systematically reduced throughout the product design cycle. This paper begins with an overview of the thermal design methodology. Direct application of the methodology to the design of an enterprise server, the RP8400, is discussed. Numerical modeling and empirical results are presented and compared, followed by a discussion of methods for improving thermal design in future products.","PeriodicalId":299933,"journal":{"name":"ITherm 2002. Eighth Intersociety Conference on Thermal and Thermomechanical Phenomena in Electronic Systems (Cat. No.02CH37258)","volume":"82 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2002-08-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"134206918","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 : 2002-08-07DOI: 10.1109/ITHERM.2002.1012543
G. Glinski, C. Bailey
The curing of conductive adhesives and underfills can save considerable time and offer cost benefits for the microsystems and electronics packaging industry. In contrast to conventional ovens, curing by microwave energy generates heat internally within each individual component of an assembly. The rate at which heat is generated is different for each of the components and depends on the material properties as well as the oven power and frequency. This leads to a very complex and transient thermal state, which is extremely difficult to measure experimentally. Conductive adhesives need to be raised to a minimum temperature to initiate the cross-linking of the resin polymers, whilst some advanced packaging materials currently under investigation impose a maximum temperature constraint to avoid damage. Thermal imagery equipment integrated with the microwave oven can offer some information on the thermal state but such data is based on the surface temperatures. This paper describes computational models that can simulate the internal temperatures within each component of an assembly including the critical region between the chip and substrate. The results obtained demonstrate that due to the small mass of adhesive used in the joints, the temperatures reached are highly dependent on the material properties of the adjacent chip and substrate.
{"title":"Microwave cure of conductive adhesives for flip-chip & microsystems applications","authors":"G. Glinski, C. Bailey","doi":"10.1109/ITHERM.2002.1012543","DOIUrl":"https://doi.org/10.1109/ITHERM.2002.1012543","url":null,"abstract":"The curing of conductive adhesives and underfills can save considerable time and offer cost benefits for the microsystems and electronics packaging industry. In contrast to conventional ovens, curing by microwave energy generates heat internally within each individual component of an assembly. The rate at which heat is generated is different for each of the components and depends on the material properties as well as the oven power and frequency. This leads to a very complex and transient thermal state, which is extremely difficult to measure experimentally. Conductive adhesives need to be raised to a minimum temperature to initiate the cross-linking of the resin polymers, whilst some advanced packaging materials currently under investigation impose a maximum temperature constraint to avoid damage. Thermal imagery equipment integrated with the microwave oven can offer some information on the thermal state but such data is based on the surface temperatures. This paper describes computational models that can simulate the internal temperatures within each component of an assembly including the critical region between the chip and substrate. The results obtained demonstrate that due to the small mass of adhesive used in the joints, the temperatures reached are highly dependent on the material properties of the adjacent chip and substrate.","PeriodicalId":299933,"journal":{"name":"ITherm 2002. Eighth Intersociety Conference on Thermal and Thermomechanical Phenomena in Electronic Systems (Cat. No.02CH37258)","volume":"27 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2002-08-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"132613551","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 : 2002-08-07DOI: 10.1109/ITHERM.2002.1012570
D. Sadler, R. Changrani, P. Roberts, C. Chou, F. Zenhausern
Integrated microfluidic devices for amplification and detection of biological samples that employ closed-loop temperature monitoring and control have been demonstrated within a multilayer low temperature co-fired ceramics (LTCC) platform. Devices designed within this platform demonstrate a high level of integration including integrated microfluidic channels, thick-film screen-printed Ag-Pd heaters, surface mounted temperature sensors, and air-gaps for thermal isolation. In addition, thermal-fluidic finite element models have been developed using CFDRC ACE+ software which allow for optimization of such parameters as heater input power, fluid flow rate, sensor placement, and air-gap size and placement. Two examples of devices that make use of these concepts are provided. The first is a continuous flow polymerase chain reaction (PCR) device that requires three thermally isolated zones of 94/spl deg/C, 65/spl deg/C, and 72/spl deg/C, and the second is an electronic DNA detection chip which requires hybridization at 35/spl deg/C. Both devices contain integrated heaters and surface mount silicon transistors which function as temperature sensors. Closed loop feedback control is provided by an external PI controller that monitors the temperature dependent I-V relationship of the sensor and adjusts heater power accordingly. Experimental data confirms that better than +/- 0.5/spl deg/C can be maintained for these devices irrespective of changing ambient conditions. In addition, excellent matching with model predictions has been achieved, thus providing a powerful design tool for thermal-fluidic microsystems.
{"title":"Thermal management of BioMEMS","authors":"D. Sadler, R. Changrani, P. Roberts, C. Chou, F. Zenhausern","doi":"10.1109/ITHERM.2002.1012570","DOIUrl":"https://doi.org/10.1109/ITHERM.2002.1012570","url":null,"abstract":"Integrated microfluidic devices for amplification and detection of biological samples that employ closed-loop temperature monitoring and control have been demonstrated within a multilayer low temperature co-fired ceramics (LTCC) platform. Devices designed within this platform demonstrate a high level of integration including integrated microfluidic channels, thick-film screen-printed Ag-Pd heaters, surface mounted temperature sensors, and air-gaps for thermal isolation. In addition, thermal-fluidic finite element models have been developed using CFDRC ACE+ software which allow for optimization of such parameters as heater input power, fluid flow rate, sensor placement, and air-gap size and placement. Two examples of devices that make use of these concepts are provided. The first is a continuous flow polymerase chain reaction (PCR) device that requires three thermally isolated zones of 94/spl deg/C, 65/spl deg/C, and 72/spl deg/C, and the second is an electronic DNA detection chip which requires hybridization at 35/spl deg/C. Both devices contain integrated heaters and surface mount silicon transistors which function as temperature sensors. Closed loop feedback control is provided by an external PI controller that monitors the temperature dependent I-V relationship of the sensor and adjusts heater power accordingly. Experimental data confirms that better than +/- 0.5/spl deg/C can be maintained for these devices irrespective of changing ambient conditions. In addition, excellent matching with model predictions has been achieved, thus providing a powerful design tool for thermal-fluidic microsystems.","PeriodicalId":299933,"journal":{"name":"ITherm 2002. Eighth Intersociety Conference on Thermal and Thermomechanical Phenomena in Electronic Systems (Cat. No.02CH37258)","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2002-08-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"130494372","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 : 2002-08-07DOI: 10.1109/ITHERM.2002.1012442
S. E. Larson
Three-dimensional, transient computational fluid-dynamic (CFD) models require finite-volume grids in the spatial as well as temporal domain. The grid can become extremely large, even for component-level problems. This initially results in long computation times during grid optimization, even with high-speed and parallel processing computers. It also results in extremely long computation times once the grid has been optimized. Solution times are further increased when the transient load is cyclic in nature. To reduce computation time, lumped resistance-capacitance (R/sub th/C/sub th/) methods developed by Larson and Li [2000] were benchmarked at the component level, then the system level. Next, the use of root-mean-squared current (I.) as a steady-state approximation was benchmarked at both the component and system level. Finally, both methods were applied to streamline the analysis of automotive electronic controls. Limitations of both the R/sub th/C/sub th/ and steady-state methods are discussed. Cycle time reduction values for both component and system level are presented.
{"title":"Application of lumped R/sub th/C/sub th/ and approximate steady-state methods for reducing transient analysis solution time","authors":"S. E. Larson","doi":"10.1109/ITHERM.2002.1012442","DOIUrl":"https://doi.org/10.1109/ITHERM.2002.1012442","url":null,"abstract":"Three-dimensional, transient computational fluid-dynamic (CFD) models require finite-volume grids in the spatial as well as temporal domain. The grid can become extremely large, even for component-level problems. This initially results in long computation times during grid optimization, even with high-speed and parallel processing computers. It also results in extremely long computation times once the grid has been optimized. Solution times are further increased when the transient load is cyclic in nature. To reduce computation time, lumped resistance-capacitance (R/sub th/C/sub th/) methods developed by Larson and Li [2000] were benchmarked at the component level, then the system level. Next, the use of root-mean-squared current (I.) as a steady-state approximation was benchmarked at both the component and system level. Finally, both methods were applied to streamline the analysis of automotive electronic controls. Limitations of both the R/sub th/C/sub th/ and steady-state methods are discussed. Cycle time reduction values for both component and system level are presented.","PeriodicalId":299933,"journal":{"name":"ITherm 2002. Eighth Intersociety Conference on Thermal and Thermomechanical Phenomena in Electronic Systems (Cat. No.02CH37258)","volume":" 47","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2002-08-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"113951269","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 : 2002-08-07DOI: 10.1109/ITHERM.2002.1012577
T. Fisher, D. G. Walker
This paper considers the effect of anode heating from high-energy electrons produced by field emission. Large fields accelerate emitted electrons as they traverse a vacuum gap toward the anode. Electron energy is transferred to the anode by collisions with the lattice. The nonequilibrium transfer of electron kinetic energy to anode thermal energy is examined. Results demonstrate that the energy distribution of impinging electrons affects the transmission and dissipation of thermal energy. A Monte Carlo technique is used to resolve the thermalization of electrons and accounts for electron beam strength and spatial distribution. The results indicate that local heat fluxes of the order 10 kW/cm/sup 2/ occur at the anode surface and that heating is a strong function of field strength because of the exponential relationship between applied voltage and current. Under practical conditions, temperature increases of 10/spl deg/C are predicted from a single point emission source.
{"title":"Analysis and simulation of anode heating from electron field emission","authors":"T. Fisher, D. G. Walker","doi":"10.1109/ITHERM.2002.1012577","DOIUrl":"https://doi.org/10.1109/ITHERM.2002.1012577","url":null,"abstract":"This paper considers the effect of anode heating from high-energy electrons produced by field emission. Large fields accelerate emitted electrons as they traverse a vacuum gap toward the anode. Electron energy is transferred to the anode by collisions with the lattice. The nonequilibrium transfer of electron kinetic energy to anode thermal energy is examined. Results demonstrate that the energy distribution of impinging electrons affects the transmission and dissipation of thermal energy. A Monte Carlo technique is used to resolve the thermalization of electrons and accounts for electron beam strength and spatial distribution. The results indicate that local heat fluxes of the order 10 kW/cm/sup 2/ occur at the anode surface and that heating is a strong function of field strength because of the exponential relationship between applied voltage and current. Under practical conditions, temperature increases of 10/spl deg/C are predicted from a single point emission source.","PeriodicalId":299933,"journal":{"name":"ITherm 2002. Eighth Intersociety Conference on Thermal and Thermomechanical Phenomena in Electronic Systems (Cat. No.02CH37258)","volume":"69 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2002-08-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124428829","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 : 2002-08-07DOI: 10.1109/ITHERM.2002.1012552
R. Kiumi, J. Yoshioka, F. Kuriyama, N. Saito, M. Shimoyama
Eutectic tin-silver (Sn-Ag), tin-copper (Sn-Cu), and tin-silver-copper (Sn-Ag-Cu) solder alloys are potential lead-free materials for low-temperature processing of solder bumps on wafers. But, before they can be adopted to replace the existing lead-free materials, processes have to be developed to provide controls over composition, height and shape uniformity, and defect formation, such as micro-voids, which are detrimental to bump reliability. Over the last six years, we have developed an electroplating technology using a dip-plating machine for processing the three types of eutectic lead-free solder bumps on silicon wafer. Our process is suitable for mass production with well-controlled bump geometry and composition, and uniformity within 10% over the entire wafer. In this paper, we will describe our process and present our results on the bump properties, such as composition, melting point, and microstructure of the bumps.
{"title":"Processing, properties, and reliability of electroplated lead-free solder bumps","authors":"R. Kiumi, J. Yoshioka, F. Kuriyama, N. Saito, M. Shimoyama","doi":"10.1109/ITHERM.2002.1012552","DOIUrl":"https://doi.org/10.1109/ITHERM.2002.1012552","url":null,"abstract":"Eutectic tin-silver (Sn-Ag), tin-copper (Sn-Cu), and tin-silver-copper (Sn-Ag-Cu) solder alloys are potential lead-free materials for low-temperature processing of solder bumps on wafers. But, before they can be adopted to replace the existing lead-free materials, processes have to be developed to provide controls over composition, height and shape uniformity, and defect formation, such as micro-voids, which are detrimental to bump reliability. Over the last six years, we have developed an electroplating technology using a dip-plating machine for processing the three types of eutectic lead-free solder bumps on silicon wafer. Our process is suitable for mass production with well-controlled bump geometry and composition, and uniformity within 10% over the entire wafer. In this paper, we will describe our process and present our results on the bump properties, such as composition, melting point, and microstructure of the bumps.","PeriodicalId":299933,"journal":{"name":"ITherm 2002. Eighth Intersociety Conference on Thermal and Thermomechanical Phenomena in Electronic Systems (Cat. No.02CH37258)","volume":"92 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2002-08-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"122742462","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}
京公网安备 11010802042870号
京ICP备2023020795号-1
扫码关注我们
求助内容：
应助结果提醒方式：