Pub Date : 2007-08-01DOI: 10.1109/ICEPT.2007.4441480
L. Mao, Z.O. Wang
The effects of a vacancy on the electronic conductance in a finite one dimensional imperfect quantum wire represents by a sequence of delta function potential were discussed. The results show that the peak of the maximum electronic conductance in the forbidden band caused by vacancy will be largely affected if the position of the vacancy changes. And the position of vacancy is found to have a little effect on the position of the maximum electronic conductance in the forbidden region. All these results demonstrate that for one vacancy existing in a nanowire, the electronic conductance in the conduction band will be deteriorated due to destructive interference of electronic waves.
{"title":"Simulation the Effect of the Defect on the Conductance of Nanowire","authors":"L. Mao, Z.O. Wang","doi":"10.1109/ICEPT.2007.4441480","DOIUrl":"https://doi.org/10.1109/ICEPT.2007.4441480","url":null,"abstract":"The effects of a vacancy on the electronic conductance in a finite one dimensional imperfect quantum wire represents by a sequence of delta function potential were discussed. The results show that the peak of the maximum electronic conductance in the forbidden band caused by vacancy will be largely affected if the position of the vacancy changes. And the position of vacancy is found to have a little effect on the position of the maximum electronic conductance in the forbidden region. All these results demonstrate that for one vacancy existing in a nanowire, the electronic conductance in the conduction band will be deteriorated due to destructive interference of electronic waves.","PeriodicalId":325619,"journal":{"name":"2007 8th International Conference on Electronic Packaging Technology","volume":"28 26 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":"124715609","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.2007.4441386
Dapeng Zhu, Jiuirong Guo, L. Luo
The Kelvin structure was designed on alumina MCM-D substrate to evaluate the substrate electromigration (EM) reliability. The Median Time To Failure (t50) and the resistance shift of the interconnection via of Kelvin structure were measured by applying different current (DC) under different ambient temperatures. A thermal compensation method was adopted which ensured the packaged test structures fail at the same condition. The test results show that the active energy and the current density exponent of anodic alumina substrate are 0.57 eV and 1.03 respectively. The failure of the Kelvin structure during EM test is caused by the void formation at the interconnection of lines and vias where the current bending in 90-degree corner accelerate the EM process.
{"title":"Electromigration Study on Micro-vias of Multi-layer Anodic Alumina Substrate with a Thermal Compensated on-line Measurement Scheme","authors":"Dapeng Zhu, Jiuirong Guo, L. Luo","doi":"10.1109/ICEPT.2007.4441386","DOIUrl":"https://doi.org/10.1109/ICEPT.2007.4441386","url":null,"abstract":"The Kelvin structure was designed on alumina MCM-D substrate to evaluate the substrate electromigration (EM) reliability. The Median Time To Failure (t50) and the resistance shift of the interconnection via of Kelvin structure were measured by applying different current (DC) under different ambient temperatures. A thermal compensation method was adopted which ensured the packaged test structures fail at the same condition. The test results show that the active energy and the current density exponent of anodic alumina substrate are 0.57 eV and 1.03 respectively. The failure of the Kelvin structure during EM test is caused by the void formation at the interconnection of lines and vias where the current bending in 90-degree corner accelerate the EM process.","PeriodicalId":325619,"journal":{"name":"2007 8th International Conference on Electronic Packaging Technology","volume":"227 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":"122372510","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.2007.4441538
Dong Wang, Xiaosong Ma, Dan Guo
The purpose of this paper is to study effect of thermal cycle condition on the reliability of lead-free flip chip solder joint. Flip chip assembly was subjected to thermal cycle (MIT-STD-883) condition. Two dimensional finite element analysis (FEA) has been carried out using ANSYS commercial software. There are two types of lead-free solder (Sn96.5-Ag3.5 and Sn95.5-Ag3.8-Cu0.7). They used flip chip solder joints have been evaluated. For each lead-free flip chip solder joint, thermal stress and strain have been studied. The plastic strain is mainly effect on thermal fatigue of solder joint, so two types of lead-free solder joint compare with Sn63-Pb37 solder joint in equivalent plastic strain, and thermal fatigue life of these three types of solder joint has been analyzed and assessed.
{"title":"Reliability Analysis of Lead-free Flip Chip Solder Joint","authors":"Dong Wang, Xiaosong Ma, Dan Guo","doi":"10.1109/ICEPT.2007.4441538","DOIUrl":"https://doi.org/10.1109/ICEPT.2007.4441538","url":null,"abstract":"The purpose of this paper is to study effect of thermal cycle condition on the reliability of lead-free flip chip solder joint. Flip chip assembly was subjected to thermal cycle (MIT-STD-883) condition. Two dimensional finite element analysis (FEA) has been carried out using ANSYS commercial software. There are two types of lead-free solder (Sn96.5-Ag3.5 and Sn95.5-Ag3.8-Cu0.7). They used flip chip solder joints have been evaluated. For each lead-free flip chip solder joint, thermal stress and strain have been studied. The plastic strain is mainly effect on thermal fatigue of solder joint, so two types of lead-free solder joint compare with Sn63-Pb37 solder joint in equivalent plastic strain, and thermal fatigue life of these three types of solder joint has been analyzed and assessed.","PeriodicalId":325619,"journal":{"name":"2007 8th International Conference on Electronic Packaging Technology","volume":"31 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":"128566536","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.2007.4441562
Y.C. Lee
Packaging is critical to the advancement of microsystems integrating microelectromechanical systems (MEMS) with microelectronic, optoelectronic and microwave devices. This paper discusses microsystems packaging with three cases: a) packaging of MEMS: flip-chip assembly to interconnect MEMS devices with other components; b) packaging for MEMS: novel MEMS devices fabricated using packaging technologies such as flexible circuit; and c) MEMS for packaging: MEMS devices used for active alignment for optoelectronic packaging. With such a close relationship between packaging and MEMS, we expect to see many novel microsystems with packaging and MEMS technologies fully integrated in the future.
{"title":"Packaging and Microelectromechanical Systems (MEMS)","authors":"Y.C. Lee","doi":"10.1109/ICEPT.2007.4441562","DOIUrl":"https://doi.org/10.1109/ICEPT.2007.4441562","url":null,"abstract":"Packaging is critical to the advancement of microsystems integrating microelectromechanical systems (MEMS) with microelectronic, optoelectronic and microwave devices. This paper discusses microsystems packaging with three cases: a) packaging of MEMS: flip-chip assembly to interconnect MEMS devices with other components; b) packaging for MEMS: novel MEMS devices fabricated using packaging technologies such as flexible circuit; and c) MEMS for packaging: MEMS devices used for active alignment for optoelectronic packaging. With such a close relationship between packaging and MEMS, we expect to see many novel microsystems with packaging and MEMS technologies fully integrated in the future.","PeriodicalId":325619,"journal":{"name":"2007 8th International Conference on Electronic Packaging Technology","volume":"1 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":"129835291","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.2007.4441494
Y. Ai, Xiaobing Luo, Sheng Liu
This paper presents the design and modeling of a micromachined thermal convective gyroscope with bidirectional jets. Unlike earlier reported thermal convective gyroscopes, the proposed gyroscope comprises two chambers for gas jet deflection. Mathematical analysis was applied to investigate the centrifugal acceleration coupling in both single directional jet detection method and bidirectional jets detection method. Analysis results revealed that bidirectional jets detection method can effectively reduce centrifugal acceleration coupling which induces the nonlinearity of the output electric signal. The applicable range of bidirectional jets detection method is twice wider than that of single directional jet detection method. Numerical simulation was applied to investigate the gyroscope performance, which concluded that the temperature difference DeltaT shows good linearity to the angular rate omega, the nonlinearity is 0.6%. The sensitivity of the proposed gyroscope was estimated to be 1.26mV/deg/s with the supply voltage of 15 V.
{"title":"Design and Modeling of Micromachined Thermal Convective Gyroscope with Bidirectional Jets","authors":"Y. Ai, Xiaobing Luo, Sheng Liu","doi":"10.1109/ICEPT.2007.4441494","DOIUrl":"https://doi.org/10.1109/ICEPT.2007.4441494","url":null,"abstract":"This paper presents the design and modeling of a micromachined thermal convective gyroscope with bidirectional jets. Unlike earlier reported thermal convective gyroscopes, the proposed gyroscope comprises two chambers for gas jet deflection. Mathematical analysis was applied to investigate the centrifugal acceleration coupling in both single directional jet detection method and bidirectional jets detection method. Analysis results revealed that bidirectional jets detection method can effectively reduce centrifugal acceleration coupling which induces the nonlinearity of the output electric signal. The applicable range of bidirectional jets detection method is twice wider than that of single directional jet detection method. Numerical simulation was applied to investigate the gyroscope performance, which concluded that the temperature difference DeltaT shows good linearity to the angular rate omega, the nonlinearity is 0.6%. The sensitivity of the proposed gyroscope was estimated to be 1.26mV/deg/s with the supply voltage of 15 V.","PeriodicalId":325619,"journal":{"name":"2007 8th International Conference on Electronic Packaging Technology","volume":"15 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":"128038200","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.2007.4441425
Hongwen He, Guangchen Xu, H. Hao, F. Guo
Electromigration is one of the severe reliability problems in IC progress. In this paper, the electromigration of eutectic Sn3.8Ag0.7Cu solder reaction couples were studied under high temperature (150degC) and high current density (5times103 A/cm2) in three days. An original design which could reduce the local Joule heating caused by current crowding was produced. Voltage change was also monitored during this experiment. Hillocks and valleys were found at the anode side and cathode side respectively. Unlike aging test, electromigration could promote the formation of intermetallic compound (IMC) at cathode side and inhibit the formation of IMC at anode side. Cracks also appeared along the cathode side after electromigration in three days, but they were not leading the solder reaction couple to failure.
{"title":"Electromigration in Lead-Free Sn3.8Ag0.7Cu Solder Reaction Couple","authors":"Hongwen He, Guangchen Xu, H. Hao, F. Guo","doi":"10.1109/ICEPT.2007.4441425","DOIUrl":"https://doi.org/10.1109/ICEPT.2007.4441425","url":null,"abstract":"Electromigration is one of the severe reliability problems in IC progress. In this paper, the electromigration of eutectic Sn3.8Ag0.7Cu solder reaction couples were studied under high temperature (150degC) and high current density (5times103 A/cm2) in three days. An original design which could reduce the local Joule heating caused by current crowding was produced. Voltage change was also monitored during this experiment. Hillocks and valleys were found at the anode side and cathode side respectively. Unlike aging test, electromigration could promote the formation of intermetallic compound (IMC) at cathode side and inhibit the formation of IMC at anode side. Cracks also appeared along the cathode side after electromigration in three days, but they were not leading the solder reaction couple to failure.","PeriodicalId":325619,"journal":{"name":"2007 8th International Conference on Electronic Packaging Technology","volume":"1 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":"128452468","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.2007.4441473
W. Fang, Hongbo Yang, Ming Zhou, A. Tsui
Nowadays, power management semiconductor suppliers have taken big steps to provide environmentally sound and green product solutions to meet the ever increasing demand of high performance electronics in the global consumer, industrial, computer, communication and automotive markets. The challenges are two fold. Very strict reliability performance and the green requirements have to be met at the same time. These requirements mainly bring three challenges to current electronic device manufacturers: Lead-free plating process, green compound package and Pb-free die attach materials. GEM. as an international power management manufacturing services provider, has already taken action to meet the global new requirement. In tins paper, the research path and process improvement of green package manufacturing in GEM is presented, and the packaging trend of future high power and high thermal capability power management device is also discussed.
{"title":"Green Policy in an International Power Management Manufacturing Services Provider in China","authors":"W. Fang, Hongbo Yang, Ming Zhou, A. Tsui","doi":"10.1109/ICEPT.2007.4441473","DOIUrl":"https://doi.org/10.1109/ICEPT.2007.4441473","url":null,"abstract":"Nowadays, power management semiconductor suppliers have taken big steps to provide environmentally sound and green product solutions to meet the ever increasing demand of high performance electronics in the global consumer, industrial, computer, communication and automotive markets. The challenges are two fold. Very strict reliability performance and the green requirements have to be met at the same time. These requirements mainly bring three challenges to current electronic device manufacturers: Lead-free plating process, green compound package and Pb-free die attach materials. GEM. as an international power management manufacturing services provider, has already taken action to meet the global new requirement. In tins paper, the research path and process improvement of green package manufacturing in GEM is presented, and the packaging trend of future high power and high thermal capability power management device is also discussed.","PeriodicalId":325619,"journal":{"name":"2007 8th International Conference on Electronic Packaging Technology","volume":"97 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":"122218181","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.2007.4441537
Wang Geng-lin, Wang Li-yan, Dong Li-jun, Huang Zheng
In the course of analyzing and deducing leak rate formula of fine leak test measurement of helium mass spectrometer, equivalent standard leak rate L is replaced with standard helium leak rate LHe . Helium gas exchange time constant zetaHe is cited, and the contents of typical gases inside hermetic cavity is calculated. It shows that after properly handling the measured leak rate deviation, a series of formulas of the paper can be used to perform engineering calculation on the process of gas exchange. zetaHes are calculated corresponding to leak rate criterion under various test conditions of current Chinese national military standards and US military standards in fine leak test of helium mass spectrometer, so real LHe is preferable to virtual L. Additionally, it is noted that zetaHe is the characteristic parameter to measure the relative hermeticity, and especially, most leak rate criterions in current military standards cannot guarantee meeting the requirement of internal vapor content, so by analyzing the improvement in the standards and existing hermeticity levels, it is evident that there still exists the necessity for the standards to be further improved.
{"title":"Study on Leak Rate Formula and Criterion for Helium Mass Spectrometer Fine Leak Test","authors":"Wang Geng-lin, Wang Li-yan, Dong Li-jun, Huang Zheng","doi":"10.1109/ICEPT.2007.4441537","DOIUrl":"https://doi.org/10.1109/ICEPT.2007.4441537","url":null,"abstract":"In the course of analyzing and deducing leak rate formula of fine leak test measurement of helium mass spectrometer, equivalent standard leak rate L is replaced with standard helium leak rate LHe . Helium gas exchange time constant zetaHe is cited, and the contents of typical gases inside hermetic cavity is calculated. It shows that after properly handling the measured leak rate deviation, a series of formulas of the paper can be used to perform engineering calculation on the process of gas exchange. zetaHes are calculated corresponding to leak rate criterion under various test conditions of current Chinese national military standards and US military standards in fine leak test of helium mass spectrometer, so real LHe is preferable to virtual L. Additionally, it is noted that zetaHe is the characteristic parameter to measure the relative hermeticity, and especially, most leak rate criterions in current military standards cannot guarantee meeting the requirement of internal vapor content, so by analyzing the improvement in the standards and existing hermeticity levels, it is evident that there still exists the necessity for the standards to be further improved.","PeriodicalId":325619,"journal":{"name":"2007 8th International Conference on Electronic Packaging Technology","volume":"152 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":"122828670","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.2007.4441439
Feng Gao, C. P. Wang, X. J. Liu, K. Ishida
Sn-Ag-Cu base solders are the most potential candidates to substitute of Sn-Pb eutectic solder. Gold (Au) coatings are used to protect conductor surface from oxidation and thereby to promote the solderability, and nickel (Ni) is often used as a diffusion barrier layer between lead-free solders and substrates to restrict the growing of intermetallic compound layers. And the gold and nickel also are added to the Pb-free solders to improve their performance. In the present work, the thermodynamic calculations of phase equilibria in the Sn-Ag-Cu-Ni-Au system were carried out using the CALPHAD method. Some examples of application are presented, and it is shown that the CALPHAD method is a good tool to design Pb-free solders and understand the interfacial reaction.
{"title":"Thermodynamic Calculation of Phase Equilibria and Its Applications in the Sn-Ag-Cu-Ni-Au System","authors":"Feng Gao, C. P. Wang, X. J. Liu, K. Ishida","doi":"10.1109/ICEPT.2007.4441439","DOIUrl":"https://doi.org/10.1109/ICEPT.2007.4441439","url":null,"abstract":"Sn-Ag-Cu base solders are the most potential candidates to substitute of Sn-Pb eutectic solder. Gold (Au) coatings are used to protect conductor surface from oxidation and thereby to promote the solderability, and nickel (Ni) is often used as a diffusion barrier layer between lead-free solders and substrates to restrict the growing of intermetallic compound layers. And the gold and nickel also are added to the Pb-free solders to improve their performance. In the present work, the thermodynamic calculations of phase equilibria in the Sn-Ag-Cu-Ni-Au system were carried out using the CALPHAD method. Some examples of application are presented, and it is shown that the CALPHAD method is a good tool to design Pb-free solders and understand the interfacial reaction.","PeriodicalId":325619,"journal":{"name":"2007 8th International Conference on Electronic Packaging Technology","volume":"24 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":"125940932","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.2007.4441382
Y. Chapuis, A. Debray, H. Fujita
In this paper, we discuss a flip-chip packaging method using liquid solder for 3D large-scale electronic/MEMS co-integration. This approach has been inspired from self-assembly technique which is emerging as one of the main methods for fabrication of heterogeneous micro-and nano-systems. We proposed to form solder bump by coating liquid solder directly on electrodes of a MEMS chip based on sophisticate microstructures of electrostatic microactuator array. Self-alignment and assembly techniques for electronic receptor chip were also detailed in order to achieve efficient flip-chip of MEMS and Electronic chip without any stiction and contamination problem. Functionality of the system has been validated and perspectives discussed.
{"title":"3-D Large-Scale IC/MEMS Co-Integration Using Liquid Solder for Flip-Chip Assembly","authors":"Y. Chapuis, A. Debray, H. Fujita","doi":"10.1109/ICEPT.2007.4441382","DOIUrl":"https://doi.org/10.1109/ICEPT.2007.4441382","url":null,"abstract":"In this paper, we discuss a flip-chip packaging method using liquid solder for 3D large-scale electronic/MEMS co-integration. This approach has been inspired from self-assembly technique which is emerging as one of the main methods for fabrication of heterogeneous micro-and nano-systems. We proposed to form solder bump by coating liquid solder directly on electrodes of a MEMS chip based on sophisticate microstructures of electrostatic microactuator array. Self-alignment and assembly techniques for electronic receptor chip were also detailed in order to achieve efficient flip-chip of MEMS and Electronic chip without any stiction and contamination problem. Functionality of the system has been validated and perspectives discussed.","PeriodicalId":325619,"journal":{"name":"2007 8th International Conference on Electronic Packaging Technology","volume":"1 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":"129789990","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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