Pub Date : 2000-05-23DOI: 10.1109/ITHERM.2000.866843
S. Shidore, V. Adams, T. Lee
A previously validated detailed model of a 119-pin Flip-Chip Plastic Ball Grid Array (FC-PBGA) package was created and validated against experimental data for natural convection and forced convection environments. Next, two compact models were derived, a two-resistor model (created using the JEDEC-standard based computational approach), and a multi-resistor model (created using the DELPHI optimization approach that was boundary condition independent within engineering accuracy). The compact models were placed in natural convection and forced convection (velocities of 1 and 2 m/s) environments with and without a heatsink. Based on the agreement obtained between the detailed model and compact model simulations, the accuracy and validity of the two compact models was assessed. Of the two compact thermal models considered, the Delphi multi-resistor model provided the same predictive estimates (within 5%) as simulations involving a detailed thermal model of the package in natural and forced convection environments both with and without attached heatsinks. Some thermal modeling issues were addressed with respect to implementation of compact thermal models with attached heatsinks.
{"title":"A study of compact thermal model topologies in CFD for a flip chip plastic ball grid array package","authors":"S. Shidore, V. Adams, T. Lee","doi":"10.1109/ITHERM.2000.866843","DOIUrl":"https://doi.org/10.1109/ITHERM.2000.866843","url":null,"abstract":"A previously validated detailed model of a 119-pin Flip-Chip Plastic Ball Grid Array (FC-PBGA) package was created and validated against experimental data for natural convection and forced convection environments. Next, two compact models were derived, a two-resistor model (created using the JEDEC-standard based computational approach), and a multi-resistor model (created using the DELPHI optimization approach that was boundary condition independent within engineering accuracy). The compact models were placed in natural convection and forced convection (velocities of 1 and 2 m/s) environments with and without a heatsink. Based on the agreement obtained between the detailed model and compact model simulations, the accuracy and validity of the two compact models was assessed. Of the two compact thermal models considered, the Delphi multi-resistor model provided the same predictive estimates (within 5%) as simulations involving a detailed thermal model of the package in natural and forced convection environments both with and without attached heatsinks. Some thermal modeling issues were addressed with respect to implementation of compact thermal models with attached heatsinks.","PeriodicalId":201262,"journal":{"name":"ITHERM 2000. The Seventh Intersociety Conference on Thermal and Thermomechanical Phenomena in Electronic Systems (Cat. No.00CH37069)","volume":"23 2 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2000-05-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"127813309","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2000-05-23DOI: 10.1109/ITHERM.2000.866844
J.Y. Chang, C. Yu, R. Webb
This paper reports the results of CFD analysis to cool the 30-W socketed CPU of a desktop computer with minimum air flow rate and minimum heat sink size. This was achieved using only the fan in the power supply for all air movement in the chassis. A duct was employed to direct the air flow over the CPU and then to the inlet air vents of the power supply. Use of this duct allowed more than 10/spl deg/C reduction of the CPU case temperature, relative to a unducted design. The CFD analysis results were confirmed by experiment, and the predicted CPU case temperatures agreed within /spl plusmn/2.9/spl deg/C of the experimental values for the ducted cases. This paper describes the methodology of CFD analysis for the heat sink/duct design, and describes experimental procedures to validate the predictions.
{"title":"Identification of minimum air flow design for a desktop computer using CFD modeling","authors":"J.Y. Chang, C. Yu, R. Webb","doi":"10.1109/ITHERM.2000.866844","DOIUrl":"https://doi.org/10.1109/ITHERM.2000.866844","url":null,"abstract":"This paper reports the results of CFD analysis to cool the 30-W socketed CPU of a desktop computer with minimum air flow rate and minimum heat sink size. This was achieved using only the fan in the power supply for all air movement in the chassis. A duct was employed to direct the air flow over the CPU and then to the inlet air vents of the power supply. Use of this duct allowed more than 10/spl deg/C reduction of the CPU case temperature, relative to a unducted design. The CFD analysis results were confirmed by experiment, and the predicted CPU case temperatures agreed within /spl plusmn/2.9/spl deg/C of the experimental values for the ducted cases. This paper describes the methodology of CFD analysis for the heat sink/duct design, and describes experimental procedures to validate the predictions.","PeriodicalId":201262,"journal":{"name":"ITHERM 2000. The Seventh Intersociety Conference on Thermal and Thermomechanical Phenomena in Electronic Systems (Cat. No.00CH37069)","volume":"26 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2000-05-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"131865419","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2000-05-23DOI: 10.1109/ITHERM.2000.866831
Michael Yang
Simulation software is a good tool to reduce design cycles and prototypes. The accuracy of the results depend on the users' inputs. Software can provide very accurate results when the inputs are reliable. Software can provide very poor results if the model, boundary conditions, or solution parameters are not represented properly. The user, not the software, is responsible for the accuracy of the results. To adequately use software, the user must become familiar with the built in hnctions and their limits of applicability. You must have a complete understanding of thermal theory so you can judge when a calculated result is in error based on an error in your input. Both Flothenn and Icepak are popular thermal analysis computational fluid dynamics (CFD) software packages in electronic cooling. The scope of this comparison is not to be used by the reader as the only basis for selecting a CFD tool. The frst thermal study was conducted using Icepak and Flotherm to calculate heat transfer fiom an aluminum plate due to natural convection and forced convection (turbulent flow, 300 fpm) environment. Three different types of mesh sizes were compared to theory and experimental data. The second study was to simulate the thermal performance of a RF power amplifier in a steady state forced convection environment. Both Icepak and Flotherm can provide almost the same level of performance. The quality of the prediction depends on the users' background and experience.
{"title":"A comparison of using icepak and flotherm in electronic cooling","authors":"Michael Yang","doi":"10.1109/ITHERM.2000.866831","DOIUrl":"https://doi.org/10.1109/ITHERM.2000.866831","url":null,"abstract":"Simulation software is a good tool to reduce design cycles and prototypes. The accuracy of the results depend on the users' inputs. Software can provide very accurate results when the inputs are reliable. Software can provide very poor results if the model, boundary conditions, or solution parameters are not represented properly. The user, not the software, is responsible for the accuracy of the results. To adequately use software, the user must become familiar with the built in hnctions and their limits of applicability. You must have a complete understanding of thermal theory so you can judge when a calculated result is in error based on an error in your input. Both Flothenn and Icepak are popular thermal analysis computational fluid dynamics (CFD) software packages in electronic cooling. The scope of this comparison is not to be used by the reader as the only basis for selecting a CFD tool. The frst thermal study was conducted using Icepak and Flotherm to calculate heat transfer fiom an aluminum plate due to natural convection and forced convection (turbulent flow, 300 fpm) environment. Three different types of mesh sizes were compared to theory and experimental data. The second study was to simulate the thermal performance of a RF power amplifier in a steady state forced convection environment. Both Icepak and Flotherm can provide almost the same level of performance. The quality of the prediction depends on the users' background and experience.","PeriodicalId":201262,"journal":{"name":"ITHERM 2000. The Seventh Intersociety Conference on Thermal and Thermomechanical Phenomena in Electronic Systems (Cat. No.00CH37069)","volume":"28 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2000-05-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124034613","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2000-05-23DOI: 10.1109/ITHERM.2000.866804
M. Stevanovic, M. Yovanovich, J. Culham
An approximate mechanical model is developed for predicting the radius of contact between a sphere and a layered substrate. The complex solution of Chen and Engel is reduced to the simple root finding procedure for the unknown contact radius. Numerical data from the model of Chen and Engel are obtained for several combinations of layer material. It is shown that with the proper selection of dimensionless parameters the numerical results fall on a single curve that is easily correlated. Radius predictions show good agreement with experimental measurements.
{"title":"Modeling contact between rigid sphere and elastic layer bonded to rigid substrate","authors":"M. Stevanovic, M. Yovanovich, J. Culham","doi":"10.1109/ITHERM.2000.866804","DOIUrl":"https://doi.org/10.1109/ITHERM.2000.866804","url":null,"abstract":"An approximate mechanical model is developed for predicting the radius of contact between a sphere and a layered substrate. The complex solution of Chen and Engel is reduced to the simple root finding procedure for the unknown contact radius. Numerical data from the model of Chen and Engel are obtained for several combinations of layer material. It is shown that with the proper selection of dimensionless parameters the numerical results fall on a single curve that is easily correlated. Radius predictions show good agreement with experimental measurements.","PeriodicalId":201262,"journal":{"name":"ITHERM 2000. The Seventh Intersociety Conference on Thermal and Thermomechanical Phenomena in Electronic Systems (Cat. No.00CH37069)","volume":"70 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2000-05-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"127470291","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2000-05-23DOI: 10.1109/ITHERM.2000.866850
E. Egan, G. Kelly, T. O'Donovan, D. Murtagh, L. Herard
The manufacturing process of chip-scale plastic ball grid arrays (PBGAs) can cause appreciable warpage. The simultaneous manufacture of PBGAs can be accomplished by attaching a matrix of silicon dies onto a bottom layer of substrate. The resulting structure is termed a matrix PBGA. Because the matrix PBGA has too complex a structure for a simple mechanistic model, response surface methodology (RSM) is used to construct an empirical model of the warpage. The response surface model is created by regression analysis between the design parameters and data obtained through 3D finite element simulations. Another method, the dual-curvature approach, which is based on classical mechanics, is also used to predict matrix PBGA warpage. The prediction quality of the two models, is compared using three different error metrics, and the prediction variance of the response surface model is discussed. Comparison of the dual-curvature and response surface models shows the response surface estimates to conform more closely with simulation results.
{"title":"Response surface methodology for matrix PBGA warpage prediction","authors":"E. Egan, G. Kelly, T. O'Donovan, D. Murtagh, L. Herard","doi":"10.1109/ITHERM.2000.866850","DOIUrl":"https://doi.org/10.1109/ITHERM.2000.866850","url":null,"abstract":"The manufacturing process of chip-scale plastic ball grid arrays (PBGAs) can cause appreciable warpage. The simultaneous manufacture of PBGAs can be accomplished by attaching a matrix of silicon dies onto a bottom layer of substrate. The resulting structure is termed a matrix PBGA. Because the matrix PBGA has too complex a structure for a simple mechanistic model, response surface methodology (RSM) is used to construct an empirical model of the warpage. The response surface model is created by regression analysis between the design parameters and data obtained through 3D finite element simulations. Another method, the dual-curvature approach, which is based on classical mechanics, is also used to predict matrix PBGA warpage. The prediction quality of the two models, is compared using three different error metrics, and the prediction variance of the response surface model is discussed. Comparison of the dual-curvature and response surface models shows the response surface estimates to conform more closely with simulation results.","PeriodicalId":201262,"journal":{"name":"ITHERM 2000. The Seventh Intersociety Conference on Thermal and Thermomechanical Phenomena in Electronic Systems (Cat. No.00CH37069)","volume":"8 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2000-05-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"131479506","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2000-05-23DOI: 10.1109/ITHERM.2000.866188
Y. Zhao, C. Basaran, A. Cartwright, T. Dishongh
Concurrent vibration and thermal environment is commonly encountered in the service life of electronic packaging, such as automotive, airplane, military and mobile electronic devices. Solder joint reliability has been a critical issue of the overall design of microelectronic devices. However, the contribution of vibration to thermal fatigue life of solder joints has rarely been investigated. Vibration is taken as a loading case that only causes elastic material response. Literature is scarce on vibration plasticity and vibration caused fatigue. The standard practice in the industry is to use Miner's rule to calculate combined environment fatigue life. This study shows that using Miner's rule for fatigue life under combined loading is inaccurate. There are a number of models on thermomechanical behavior of solder joints, yet few models are verified by test data obtained from actual package size solder joints under realistic thermomechanical loading. The authors see the need of such tests for the purpose of better understanding of material behavior of solder joints under thermal and vibration loading and providing a solid basis for more accurate material modeling and fatigue life prediction. This paper reports observations from a series of concurrent thermal cycling and vibration tests on 63Sn/37Pb solder joints of an actual ball grid array (BGA) package. Moire interferometry (MI) is used to measure the inelastic deformation field of solder joints with submicron resolution, A large capacity Super AGREE thermal chamber and a high acceleration electrodynamic shaker is assembled together to perform the concurrent cycling. The cyclic plasticity of solder joints and microstructure evolution are discussed and related to fatigue life prediction.
{"title":"Inelastic behavior of microelectronics solder joints under concurrent vibration and thermal cycling","authors":"Y. Zhao, C. Basaran, A. Cartwright, T. Dishongh","doi":"10.1109/ITHERM.2000.866188","DOIUrl":"https://doi.org/10.1109/ITHERM.2000.866188","url":null,"abstract":"Concurrent vibration and thermal environment is commonly encountered in the service life of electronic packaging, such as automotive, airplane, military and mobile electronic devices. Solder joint reliability has been a critical issue of the overall design of microelectronic devices. However, the contribution of vibration to thermal fatigue life of solder joints has rarely been investigated. Vibration is taken as a loading case that only causes elastic material response. Literature is scarce on vibration plasticity and vibration caused fatigue. The standard practice in the industry is to use Miner's rule to calculate combined environment fatigue life. This study shows that using Miner's rule for fatigue life under combined loading is inaccurate. There are a number of models on thermomechanical behavior of solder joints, yet few models are verified by test data obtained from actual package size solder joints under realistic thermomechanical loading. The authors see the need of such tests for the purpose of better understanding of material behavior of solder joints under thermal and vibration loading and providing a solid basis for more accurate material modeling and fatigue life prediction. This paper reports observations from a series of concurrent thermal cycling and vibration tests on 63Sn/37Pb solder joints of an actual ball grid array (BGA) package. Moire interferometry (MI) is used to measure the inelastic deformation field of solder joints with submicron resolution, A large capacity Super AGREE thermal chamber and a high acceleration electrodynamic shaker is assembled together to perform the concurrent cycling. The cyclic plasticity of solder joints and microstructure evolution are discussed and related to fatigue life prediction.","PeriodicalId":201262,"journal":{"name":"ITHERM 2000. The Seventh Intersociety Conference on Thermal and Thermomechanical Phenomena in Electronic Systems (Cat. No.00CH37069)","volume":"2 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2000-05-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"130299371","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2000-05-23DOI: 10.1109/ITHERM.2000.866173
L. Mercado, V. Sarihan
Increasing die size and large CTE (Coefficient of Thermal Expansion) mismatch in FC-PBGA (Flip-Chip Plastic Ball Grid Array) packages have made die fractures a major failure mode during reliability testing. Most die fractures observed before was die backside vertical cracking, which was caused by excessive package bending and backside defects. However, due to die edge defects induced by the singulation process and the choice of underfill material, an increasing number of die cracks were found to initiate from die edge and propagate horizontally across the die. In order to improve package reliability and performance, die edge cracking has to be eliminated. An extensive finite element analysis was completed to investigate die edge cracking and find its solutions. A fracture mechanics approach was used to evaluate the effect of various package parameters on die edge initiated fractures. Strain energy release rate was found to be an effective technique for evaluating die edge initiated fractures from singulation-induced flaws. The impact of initial flaw size and a variety of package parameters was investigated. Unlike in die backside cracking, the dominant parameters causing die edge horizontal fractures are more closely related to local effects.
{"title":"Evaluation of die edge cracking in flip-chip PBGA packages","authors":"L. Mercado, V. Sarihan","doi":"10.1109/ITHERM.2000.866173","DOIUrl":"https://doi.org/10.1109/ITHERM.2000.866173","url":null,"abstract":"Increasing die size and large CTE (Coefficient of Thermal Expansion) mismatch in FC-PBGA (Flip-Chip Plastic Ball Grid Array) packages have made die fractures a major failure mode during reliability testing. Most die fractures observed before was die backside vertical cracking, which was caused by excessive package bending and backside defects. However, due to die edge defects induced by the singulation process and the choice of underfill material, an increasing number of die cracks were found to initiate from die edge and propagate horizontally across the die. In order to improve package reliability and performance, die edge cracking has to be eliminated. An extensive finite element analysis was completed to investigate die edge cracking and find its solutions. A fracture mechanics approach was used to evaluate the effect of various package parameters on die edge initiated fractures. Strain energy release rate was found to be an effective technique for evaluating die edge initiated fractures from singulation-induced flaws. The impact of initial flaw size and a variety of package parameters was investigated. Unlike in die backside cracking, the dominant parameters causing die edge horizontal fractures are more closely related to local effects.","PeriodicalId":201262,"journal":{"name":"ITHERM 2000. The Seventh Intersociety Conference on Thermal and Thermomechanical Phenomena in Electronic Systems (Cat. No.00CH37069)","volume":"73 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2000-05-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"115756160","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2000-05-23DOI: 10.1109/ITHERM.2000.866171
K. Wang, Y. Huang, A. Chandra, K. Hu
Interfacial shear stress, peeling stress, and die cracking stress due to thermal and elastic mismatch in layered electronic assemblies are one of the major causes of the mechanical failure of electronic packages. A simple but rather accurate method is developed to estimate these thermal stresses for packages with different layer lengths. For layered electronics with thin adhesives, analytical expressions are obtained for interfacial shear stress and peeling stress, and they agree well with the finite element analysis, especially when the moduli of adhesive layers are significantly lower than the moduli of the other layers. An analytic expression of die cracking stress is also obtained for multilayer electronic assemblies.
{"title":"Interfacial shear stress, peeling stress, and die cracking stress in trilayer electronic assemblies","authors":"K. Wang, Y. Huang, A. Chandra, K. Hu","doi":"10.1109/ITHERM.2000.866171","DOIUrl":"https://doi.org/10.1109/ITHERM.2000.866171","url":null,"abstract":"Interfacial shear stress, peeling stress, and die cracking stress due to thermal and elastic mismatch in layered electronic assemblies are one of the major causes of the mechanical failure of electronic packages. A simple but rather accurate method is developed to estimate these thermal stresses for packages with different layer lengths. For layered electronics with thin adhesives, analytical expressions are obtained for interfacial shear stress and peeling stress, and they agree well with the finite element analysis, especially when the moduli of adhesive layers are significantly lower than the moduli of the other layers. An analytic expression of die cracking stress is also obtained for multilayer electronic assemblies.","PeriodicalId":201262,"journal":{"name":"ITHERM 2000. The Seventh Intersociety Conference on Thermal and Thermomechanical Phenomena in Electronic Systems (Cat. No.00CH37069)","volume":"7 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2000-05-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"125166809","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2000-05-23DOI: 10.1109/ITHERM.2000.866201
Xi-Shu Wang, Shou-wen Yu, N. Kawagoishi
The thermal-mechanical fatigue tests were carried out at the different temperatures, axial push pull loading and both coupling cases. So that investigate the fatigue stress and/or strain in surface of specimens for Sn/Pb solder joints. Moreover, the relationship between the thermal-mechanical cyclic stress and strain were discussed for estimation the fatigue stress/strain as well as fatigue crack growth rate. According to the results of the thermal-mechanical strain to be analyzed, the thermal-mechanical fatigue stress or strain can be nearly estimated by the experimental results. And the fatigue crack growth rate can also be expressed by the term /spl Delta//spl epsi//sub eqp.//sup n'/ l using the measured strain range under the disproportional loading of thermal-mechanical coupling. The results were compared with both 62Sn38Pb and 62Sn36Pb2Ag in different experimental data. On the other hand, experimentally obtained the either thermal, mechanical or both coupling fatigue crack growth rate can be evaluated based on the small crack growth law, for many electronic solder joints materials. It is possible that thermal-mechanical fatigue crack growth rate the solder joints or/and fatigue life easily and practically predicted based on the small crack growth law.
{"title":"Estimation of the thermal-mechanical fatigue behavior of Sn/Pb solder joints","authors":"Xi-Shu Wang, Shou-wen Yu, N. Kawagoishi","doi":"10.1109/ITHERM.2000.866201","DOIUrl":"https://doi.org/10.1109/ITHERM.2000.866201","url":null,"abstract":"The thermal-mechanical fatigue tests were carried out at the different temperatures, axial push pull loading and both coupling cases. So that investigate the fatigue stress and/or strain in surface of specimens for Sn/Pb solder joints. Moreover, the relationship between the thermal-mechanical cyclic stress and strain were discussed for estimation the fatigue stress/strain as well as fatigue crack growth rate. According to the results of the thermal-mechanical strain to be analyzed, the thermal-mechanical fatigue stress or strain can be nearly estimated by the experimental results. And the fatigue crack growth rate can also be expressed by the term /spl Delta//spl epsi//sub eqp.//sup n'/ l using the measured strain range under the disproportional loading of thermal-mechanical coupling. The results were compared with both 62Sn38Pb and 62Sn36Pb2Ag in different experimental data. On the other hand, experimentally obtained the either thermal, mechanical or both coupling fatigue crack growth rate can be evaluated based on the small crack growth law, for many electronic solder joints materials. It is possible that thermal-mechanical fatigue crack growth rate the solder joints or/and fatigue life easily and practically predicted based on the small crack growth law.","PeriodicalId":201262,"journal":{"name":"ITHERM 2000. The Seventh Intersociety Conference on Thermal and Thermomechanical Phenomena in Electronic Systems (Cat. No.00CH37069)","volume":"2010 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2000-05-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"117054321","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2000-05-23DOI: 10.1109/ITHERM.2000.866852
Y. Guo, Jie-Hua Zhao
Failure induced by die cracking is one of the concerns in flip-chip packaging design and reliability study. In this paper, a thermal stress model called bi-material plate (BMP) model for analyzing flip-chip packages is developed. The analytical model, which has a closed form solution, is validated by finite element method and extensive experimental measurements for applications in flip-chip packages. Using this model, die stress and curvature can be determined effectively. It offers a significant advantage in estimating the die stress and package reliability in the process of selecting and evaluating the design and material parameters for the flip-chip packages. From this model, it is evident that the curvature and the bending stress are independent of die size if the edge effect is neglected. Further more, the bending stress is independent of absolute die thickness if substrate to die thickness ratio is kept the same. The die curvature and the bending stress have simple correlation in certain range of thickness ratio.
{"title":"A practical die stress model and its applications in flip-chip packages","authors":"Y. Guo, Jie-Hua Zhao","doi":"10.1109/ITHERM.2000.866852","DOIUrl":"https://doi.org/10.1109/ITHERM.2000.866852","url":null,"abstract":"Failure induced by die cracking is one of the concerns in flip-chip packaging design and reliability study. In this paper, a thermal stress model called bi-material plate (BMP) model for analyzing flip-chip packages is developed. The analytical model, which has a closed form solution, is validated by finite element method and extensive experimental measurements for applications in flip-chip packages. Using this model, die stress and curvature can be determined effectively. It offers a significant advantage in estimating the die stress and package reliability in the process of selecting and evaluating the design and material parameters for the flip-chip packages. From this model, it is evident that the curvature and the bending stress are independent of die size if the edge effect is neglected. Further more, the bending stress is independent of absolute die thickness if substrate to die thickness ratio is kept the same. The die curvature and the bending stress have simple correlation in certain range of thickness ratio.","PeriodicalId":201262,"journal":{"name":"ITHERM 2000. The Seventh Intersociety Conference on Thermal and Thermomechanical Phenomena in Electronic Systems (Cat. No.00CH37069)","volume":"25 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2000-05-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"116576096","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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