On the basis of MIL STD 883 method 1012 and SEMI standard G30-88 and G32-86. purely electrical approaches were implemented to measure the thermal resistance of CSOP24 package. Firstly the temperature sensitive parameter (TSP) was measured and calibrated in a temperature controlled fluid trough. Then proper test conditions including measurement current (IM) and test power PHmiddot were chosen according to experiments. Thermal resistance measurements were carried out in the two conditions: radiator with big heat sink which keeps the case temperature Tc at 60 degC. and temperature controlled fluid trough. In addition, two kinds of thermal test chips with different size (1.91times1.91mm and 3.92times3.92mm) were used to test the influence of the chip size. Experimental result was provided. Moreover, the thermal resistance of the CSOP24 package was simulated by utilizing Fluent software.
{"title":"Evaluation of the Thermal Resistance of CSOP24 Ceramic Package","authors":"Xiao Peng, Shuidi Wang, Songliang Jia, Jian Cai, Qiang Huang, Rongzhen Ding","doi":"10.1109/ICEPT.2007.4441523","DOIUrl":"https://doi.org/10.1109/ICEPT.2007.4441523","url":null,"abstract":"On the basis of MIL STD 883 method 1012 and SEMI standard G30-88 and G32-86. purely electrical approaches were implemented to measure the thermal resistance of CSOP24 package. Firstly the temperature sensitive parameter (TSP) was measured and calibrated in a temperature controlled fluid trough. Then proper test conditions including measurement current (IM) and test power PHmiddot were chosen according to experiments. Thermal resistance measurements were carried out in the two conditions: radiator with big heat sink which keeps the case temperature Tc at 60 degC. and temperature controlled fluid trough. In addition, two kinds of thermal test chips with different size (1.91times1.91mm and 3.92times3.92mm) were used to test the influence of the chip size. Experimental result was provided. Moreover, the thermal resistance of the CSOP24 package was simulated by utilizing Fluent software.","PeriodicalId":325619,"journal":{"name":"2007 8th International Conference on Electronic Packaging Technology","volume":"12 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2007-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"132208713","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 : 2007-08-01DOI: 10.1109/ICEPT.2007.4441407
Jie Bai, F. Qin, Tong An
A 3-D finite element model of board level BGA package was built and the Input-G method was used to analyze dynamic solder joint stress in the package during drop/impact. Boundary condition, bolt effects of the test board and peeling stress mechanism were emphasized in current investigation. Dynamic responses of solder joint in frequency domain and time domain were analyzed to find main mechanism of stress generation. The results show that bolt constraints have a significant influence on the dynamic stress in solder joints. The bolt constraints must be treated as zero horizontal displacement in the area the bolt acted in the numerical model. The stress in the solder joint reaches its peak at 0.4ms and the maximum peeling stress is located at the most outer corner of the package. The peeling stress is dominated by the deflection of the PCB board. Due to effect of the 5th vibrating mode, the stress-time curve of the solder joints is not smooth.
{"title":"Dynamic Stress of Solder Joints under Board-Level Drop/Impact","authors":"Jie Bai, F. Qin, Tong An","doi":"10.1109/ICEPT.2007.4441407","DOIUrl":"https://doi.org/10.1109/ICEPT.2007.4441407","url":null,"abstract":"A 3-D finite element model of board level BGA package was built and the Input-G method was used to analyze dynamic solder joint stress in the package during drop/impact. Boundary condition, bolt effects of the test board and peeling stress mechanism were emphasized in current investigation. Dynamic responses of solder joint in frequency domain and time domain were analyzed to find main mechanism of stress generation. The results show that bolt constraints have a significant influence on the dynamic stress in solder joints. The bolt constraints must be treated as zero horizontal displacement in the area the bolt acted in the numerical model. The stress in the solder joint reaches its peak at 0.4ms and the maximum peeling stress is located at the most outer corner of the package. The peeling stress is dominated by the deflection of the PCB board. Due to effect of the 5th vibrating mode, the stress-time curve of the solder joints is not smooth.","PeriodicalId":325619,"journal":{"name":"2007 8th International Conference on Electronic Packaging Technology","volume":"34 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2007-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"127636895","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 : 2007-08-01DOI: 10.1109/ICEPT.2007.4441442
L. Buenaflor, S. Dal, I. Estinozo
This paper presents the behavior of SnAgCu (SAC) solder paste when analyzed using thermal profiling when exposed to (1) conventional reflow and (2) newly adjusted profiles. Thermal gravimetric analyzer (TGA) was used extensively to study the thermal properties of the flux and to simulate the heating processes the material undergoes during ball-attach reflow process. Experiments have proved that slower ramp rate will allow gradual evaporation of volatiles prior the non-volatile reaction of flux material at soak zone. This understanding of the reaction that takes place prior to soak zone will enable ball-attach engineers to reduce the residue contamination on the ball surface by preventing the amount of solid components to be dragged atop the ball surface during rapid outgassing of solvents at a faster pre-heat ramp rate.
{"title":"Thermal Profiling to Overcome Flux Residue Formation in a No-clean Solder Paste for Lead-free Surface Mount Technology","authors":"L. Buenaflor, S. Dal, I. Estinozo","doi":"10.1109/ICEPT.2007.4441442","DOIUrl":"https://doi.org/10.1109/ICEPT.2007.4441442","url":null,"abstract":"This paper presents the behavior of SnAgCu (SAC) solder paste when analyzed using thermal profiling when exposed to (1) conventional reflow and (2) newly adjusted profiles. Thermal gravimetric analyzer (TGA) was used extensively to study the thermal properties of the flux and to simulate the heating processes the material undergoes during ball-attach reflow process. Experiments have proved that slower ramp rate will allow gradual evaporation of volatiles prior the non-volatile reaction of flux material at soak zone. This understanding of the reaction that takes place prior to soak zone will enable ball-attach engineers to reduce the residue contamination on the ball surface by preventing the amount of solid components to be dragged atop the ball surface during rapid outgassing of solvents at a faster pre-heat ramp rate.","PeriodicalId":325619,"journal":{"name":"2007 8th International Conference on Electronic Packaging Technology","volume":"5 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2007-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"121292431","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 : 2007-08-01DOI: 10.1109/ICEPT.2007.4441409
B. Jie, Q. Fei, An Tong, Na Chen
In this paper, a very detailed finite element model of PCB board and BGA package was constructed. A dynamic drop/impact simulation of the board-level package was conducted by LS-DYNA and Input-G approach under the drop Condition H recommended by JEDEC standard JESD22-B111. A PCB deflection equivalent static analysis was conducted also in order to investigate the difference of peeling stress between the dynamic and the static model.
{"title":"Influence of PCB Vibration Modal on Peeling Stress of Solder Joints in Board-level Package Under Drop Impact","authors":"B. Jie, Q. Fei, An Tong, Na Chen","doi":"10.1109/ICEPT.2007.4441409","DOIUrl":"https://doi.org/10.1109/ICEPT.2007.4441409","url":null,"abstract":"In this paper, a very detailed finite element model of PCB board and BGA package was constructed. A dynamic drop/impact simulation of the board-level package was conducted by LS-DYNA and Input-G approach under the drop Condition H recommended by JEDEC standard JESD22-B111. A PCB deflection equivalent static analysis was conducted also in order to investigate the difference of peeling stress between the dynamic and the static model.","PeriodicalId":325619,"journal":{"name":"2007 8th International Conference on Electronic Packaging Technology","volume":"11 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2007-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"123097578","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 : 2007-08-01DOI: 10.1109/ICEPT.2007.4441384
R. Aschenbrenner, E. Jung, T. Braun, U. Oestermann, J. Bauer, K. Becker, H. Reichl
A new packaging technology for a micro-electro-mechanical system (MEMS) pressure sensor was developed to allow the integration of the sensor in a probe mounted on the outside of the airplane. Thus this packaging concept will increase the reliability of equipment by avoiding extra pneumatic connections. Intrinsic advantages of this approach are the avoidance of pressure leaks and the elimination of bad pneumatic connection risk during installation or maintenance phases.
{"title":"New Sensor Packaging Concept for Avionic Application","authors":"R. Aschenbrenner, E. Jung, T. Braun, U. Oestermann, J. Bauer, K. Becker, H. Reichl","doi":"10.1109/ICEPT.2007.4441384","DOIUrl":"https://doi.org/10.1109/ICEPT.2007.4441384","url":null,"abstract":"A new packaging technology for a micro-electro-mechanical system (MEMS) pressure sensor was developed to allow the integration of the sensor in a probe mounted on the outside of the airplane. Thus this packaging concept will increase the reliability of equipment by avoiding extra pneumatic connections. Intrinsic advantages of this approach are the avoidance of pressure leaks and the elimination of bad pneumatic connection risk during installation or maintenance phases.","PeriodicalId":325619,"journal":{"name":"2007 8th International Conference on Electronic Packaging Technology","volume":"12 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2007-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"121053589","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 : 2007-08-01DOI: 10.1109/ICEPT.2007.4441376
L. Xia, Jiang Han, Jianqiang Guo, Han Zhao
Currently, ball grid array (BGA) is the mainstream technology of semiconductor package. The alignment accuracy of BGA ball mounting processing has a great impact on the rate of finished products. In order to reduce the accuracy requirement for mechanism and increase the automation level, visual servo technology is introduced to BGA ball mounting processing in tins paper. Coaxial lighting is adopted to emphasize the characteristics of positioning hole, and parallel processing flow is designed for image capture. Image smoothing and histogram equalization technology are used in image preprocessing to clear up image noise and increase image contrast. Template matching technology is used to identify the positioning hole and calculate the coordinates of positioning hole. And the difference between the coordinates of header and substrate is used as the driving signal to achieve the automatic alignment. Double-closed-loop feedback is adopted in servo system to improve positioning accuracy. And S-shape acceleration curve reduces the impact in the movement. Based on the research on the above technology, an effective scheme for automatic orientation of BGA ball mounting processing is put forward, and it will provide the great support to the development of BGA ball mounting machine.
{"title":"Technology Research on Automatic Alignment of BGA Ball Mounting Machine Based on Visual Servo","authors":"L. Xia, Jiang Han, Jianqiang Guo, Han Zhao","doi":"10.1109/ICEPT.2007.4441376","DOIUrl":"https://doi.org/10.1109/ICEPT.2007.4441376","url":null,"abstract":"Currently, ball grid array (BGA) is the mainstream technology of semiconductor package. The alignment accuracy of BGA ball mounting processing has a great impact on the rate of finished products. In order to reduce the accuracy requirement for mechanism and increase the automation level, visual servo technology is introduced to BGA ball mounting processing in tins paper. Coaxial lighting is adopted to emphasize the characteristics of positioning hole, and parallel processing flow is designed for image capture. Image smoothing and histogram equalization technology are used in image preprocessing to clear up image noise and increase image contrast. Template matching technology is used to identify the positioning hole and calculate the coordinates of positioning hole. And the difference between the coordinates of header and substrate is used as the driving signal to achieve the automatic alignment. Double-closed-loop feedback is adopted in servo system to improve positioning accuracy. And S-shape acceleration curve reduces the impact in the movement. Based on the research on the above technology, an effective scheme for automatic orientation of BGA ball mounting processing is put forward, and it will provide the great support to the development of BGA ball mounting machine.","PeriodicalId":325619,"journal":{"name":"2007 8th International Conference on Electronic Packaging Technology","volume":"27 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2007-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"116070343","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 : 2007-08-01DOI: 10.1109/ICEPT.2007.4441394
Y.Y. Ma
The relentless trend of ever increasing functionality integration and die shrinkage for cost reduction and miniaturization of products has led to intense heat dissipation in IC chips. UTAC has successfully developed a simple alternative thermal enhancement technology, which overcomes those problems inherent to HS-PBGA. Aiming to minimize prototype revisions and reduce overall turnaround time from design, to prototype, to high volume assembly production, this paper describes approaches of the design optimization for XP-BGA through mechanical and thermal modeling on designed experimental legs. Result shows that the predicted and actual measurement for thermal performance and mechanical warpage was less than 5%, and 45% respectively in terms of error range.
{"title":"Development of Multi Chip Module BGA Package for High Power Application","authors":"Y.Y. Ma","doi":"10.1109/ICEPT.2007.4441394","DOIUrl":"https://doi.org/10.1109/ICEPT.2007.4441394","url":null,"abstract":"The relentless trend of ever increasing functionality integration and die shrinkage for cost reduction and miniaturization of products has led to intense heat dissipation in IC chips. UTAC has successfully developed a simple alternative thermal enhancement technology, which overcomes those problems inherent to HS-PBGA. Aiming to minimize prototype revisions and reduce overall turnaround time from design, to prototype, to high volume assembly production, this paper describes approaches of the design optimization for XP-BGA through mechanical and thermal modeling on designed experimental legs. Result shows that the predicted and actual measurement for thermal performance and mechanical warpage was less than 5%, and 45% respectively in terms of error range.","PeriodicalId":325619,"journal":{"name":"2007 8th International Conference on Electronic Packaging Technology","volume":"34 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2007-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"114062332","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 : 2007-08-01DOI: 10.1109/ICEPT.2007.4441503
W. Jong, S. Peng
Owing to the fine pitch and the more pin counts on the higher density packaging processes, the anisotropic conductive film (ACF) is widely used for the electronic packages. The ACF is pressured to mount between the chip and the substrate so that the degree of deformation of the conductive particles can affect the performance of the package. In this study, the effects of the bonding pressures and temperatures on the chip on flex (COF) will be investigated in order to obtain the deformation of ACF. Moreover, the reliability assessment of ACF in the COF is a serious concern, such as the effect of the thermal cycles. Therefore, the behavior and reliability of components on the COF with the bonding procedures will be studied under the thermal cyclic loading in detail.
{"title":"The Influences of ACF with Bonding Processes on COF under Thermal Cyclic Loading","authors":"W. Jong, S. Peng","doi":"10.1109/ICEPT.2007.4441503","DOIUrl":"https://doi.org/10.1109/ICEPT.2007.4441503","url":null,"abstract":"Owing to the fine pitch and the more pin counts on the higher density packaging processes, the anisotropic conductive film (ACF) is widely used for the electronic packages. The ACF is pressured to mount between the chip and the substrate so that the degree of deformation of the conductive particles can affect the performance of the package. In this study, the effects of the bonding pressures and temperatures on the chip on flex (COF) will be investigated in order to obtain the deformation of ACF. Moreover, the reliability assessment of ACF in the COF is a serious concern, such as the effect of the thermal cycles. Therefore, the behavior and reliability of components on the COF with the bonding procedures will be studied under the thermal cyclic loading in detail.","PeriodicalId":325619,"journal":{"name":"2007 8th International Conference on Electronic Packaging Technology","volume":"66 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2007-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"122991401","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}
Vacuum packaging is introduced as a main mode for the MEMS (micro-electronics-mechanical-system) devices packaging. The reliability of devices in a vacuum package has become the most important part for the successful commercialization. With the decrease in the dimension and material processing, the ubiquitous surface effect between device and substrate has become more and more effective. Surface-micromachined structures formed by the wet etching of sacrificial layers are commonly plagued by problems of sticking to the substrate. The failure of devices according to the stiction has become a main factor of the MEMS reliability. In this paper, we present an experimental way to analyze the two important force of the surface effect: the capillary force and the van der Waals force. We use the cantilever beam as a classic MEMS device, and the structure of beam is specially designed for the experiment. We believe that it can greatly reduce the capillary force in the vacuum environment, so we separate the two forces through two different environmental experiments. This paper simulates different packaging environment to divide capillary force from stiction force, and analyzes the composition of the stiction force. The experimental results and theoretical summary could provide a useful reference for the design and predict the stiction failure of micro-structure.
{"title":"Effect of Vacuum Package on the Stiction Force of Micro-structure","authors":"Junwen Liu, Jing Song, Qing-An Huang, Jie-ying Tang","doi":"10.1109/ICEPT.2007.4441527","DOIUrl":"https://doi.org/10.1109/ICEPT.2007.4441527","url":null,"abstract":"Vacuum packaging is introduced as a main mode for the MEMS (micro-electronics-mechanical-system) devices packaging. The reliability of devices in a vacuum package has become the most important part for the successful commercialization. With the decrease in the dimension and material processing, the ubiquitous surface effect between device and substrate has become more and more effective. Surface-micromachined structures formed by the wet etching of sacrificial layers are commonly plagued by problems of sticking to the substrate. The failure of devices according to the stiction has become a main factor of the MEMS reliability. In this paper, we present an experimental way to analyze the two important force of the surface effect: the capillary force and the van der Waals force. We use the cantilever beam as a classic MEMS device, and the structure of beam is specially designed for the experiment. We believe that it can greatly reduce the capillary force in the vacuum environment, so we separate the two forces through two different environmental experiments. This paper simulates different packaging environment to divide capillary force from stiction force, and analyzes the composition of the stiction force. The experimental results and theoretical summary could provide a useful reference for the design and predict the stiction failure of micro-structure.","PeriodicalId":325619,"journal":{"name":"2007 8th International Conference on Electronic Packaging Technology","volume":"55 3-4","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2007-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"132811338","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 : 2007-08-01DOI: 10.1109/ICEPT.2007.4441398
Yuanxiang Zhang, Lilma Liang, Yangjian Xia, Y. Liu, S. Irving, T. Luk
Thermal simulation and analysis play a significant role in development of new generation of IC package design. However, in general IC design engineers and package engineers do not have the skills of performing such simulation and analysis. One way of overcoming tins problem is to develop a tool which can perform thermal analysis on package models automatically. Based on tins idea, a customized tool called WBExcel is developed with ANSYS workbench and Excel. It is easy for user to input necessary data in an intuitive Excel spreadsheet. After that the whole thermal simulation (including meshing, loading/boundary condition, solving, post-process and thermal results) will be completed automatically and efficiently. Tins paper introduces the general methodology of the simulation interface and system. This simulation tool has been applied to MLP package family and the results agree well with those from the normal ANSYS simulation and measurement.
{"title":"Modeling Automation System for Electronic Package Thermal Analysis using Excel Spreadsheet","authors":"Yuanxiang Zhang, Lilma Liang, Yangjian Xia, Y. Liu, S. Irving, T. Luk","doi":"10.1109/ICEPT.2007.4441398","DOIUrl":"https://doi.org/10.1109/ICEPT.2007.4441398","url":null,"abstract":"Thermal simulation and analysis play a significant role in development of new generation of IC package design. However, in general IC design engineers and package engineers do not have the skills of performing such simulation and analysis. One way of overcoming tins problem is to develop a tool which can perform thermal analysis on package models automatically. Based on tins idea, a customized tool called WBExcel is developed with ANSYS workbench and Excel. It is easy for user to input necessary data in an intuitive Excel spreadsheet. After that the whole thermal simulation (including meshing, loading/boundary condition, solving, post-process and thermal results) will be completed automatically and efficiently. Tins paper introduces the general methodology of the simulation interface and system. This simulation tool has been applied to MLP package family and the results agree well with those from the normal ANSYS simulation and measurement.","PeriodicalId":325619,"journal":{"name":"2007 8th International Conference on Electronic Packaging Technology","volume":"32 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2007-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"133233985","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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