Pub Date : 2011-12-19DOI: 10.1109/ISAPM.2011.6105724
Wenkai Mu, Wei Zhou, P. Wu
The electromigration behavior of a solder joint with Cu-core/Sn-shell structure under 1.3×104 A/cm2 was investigated in this work. As Cu has lower electrical resistivity than Sn, the Cu core was chosen primarily as the path for current flux. Compared with the traditional solder joint, this core/shell solder has two couples of cathode and anode due to the additional Cu core. It is found that most morphology changes appeared at the region where current crowding occurred according to finite element simulation. Under electron wind force, some Sn grain at the anodes rotated as a result of stress relaxation and the angle of the rotation increased with prolonging the stressing time. No obvious intermetallic compound growth was found.
研究了铜芯/锡壳结构焊点在1.3×104 a /cm2下的电迁移行为。由于铜的电阻率比锡低，因此主要选择铜铁芯作为电流通量的路径。与传统焊点相比，由于增加了铜芯，该焊点具有阴极和阳极两对。通过有限元模拟发现，形貌变化主要发生在电流拥挤发生的区域。在电子风的作用下，阳极处的Sn晶粒由于应力松弛而发生旋转，且旋转角度随应力时间的延长而增大。未发现明显的金属间化合物生长。
{"title":"Electromigration behavior of Cu-core/Sn-shell solder joints","authors":"Wenkai Mu, Wei Zhou, P. Wu","doi":"10.1109/ISAPM.2011.6105724","DOIUrl":"https://doi.org/10.1109/ISAPM.2011.6105724","url":null,"abstract":"The electromigration behavior of a solder joint with Cu-core/Sn-shell structure under 1.3×104 A/cm2 was investigated in this work. As Cu has lower electrical resistivity than Sn, the Cu core was chosen primarily as the path for current flux. Compared with the traditional solder joint, this core/shell solder has two couples of cathode and anode due to the additional Cu core. It is found that most morphology changes appeared at the region where current crowding occurred according to finite element simulation. Under electron wind force, some Sn grain at the anodes rotated as a result of stress relaxation and the angle of the rotation increased with prolonging the stressing time. No obvious intermetallic compound growth was found.","PeriodicalId":6440,"journal":{"name":"2011 International Symposium on Advanced Packaging Materials (APM)","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2011-12-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"89532045","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 : 2011-12-19DOI: 10.1109/ISAPM.2011.6105678
Jian Li, B. An, Jian Qin, Yiping Wu
A novel nano copper conductive ink, composed of anti-oxidation nano copper particles and chemical additives, had been successfully developed and employed for RFID application. A pattern of UHF RFID antenna was chosen to print on polyimide (PI) film by ink-jet printing, and then cured by UV light to form the copper wire. The adhesion of the nano copper ink film on PI was checked by cross cut tape test, and the results showed 100% film remained. As the RFID antennas and RF chips were packaged by anisotropic conductive adhesive to form the RFID inlays, the reading distance of the inlays can reach 3 meters. This proved that nano copper conductive ink had a potential for RFID application.
{"title":"Nano copper conductive ink for RFID application","authors":"Jian Li, B. An, Jian Qin, Yiping Wu","doi":"10.1109/ISAPM.2011.6105678","DOIUrl":"https://doi.org/10.1109/ISAPM.2011.6105678","url":null,"abstract":"A novel nano copper conductive ink, composed of anti-oxidation nano copper particles and chemical additives, had been successfully developed and employed for RFID application. A pattern of UHF RFID antenna was chosen to print on polyimide (PI) film by ink-jet printing, and then cured by UV light to form the copper wire. The adhesion of the nano copper ink film on PI was checked by cross cut tape test, and the results showed 100% film remained. As the RFID antennas and RF chips were packaged by anisotropic conductive adhesive to form the RFID inlays, the reading distance of the inlays can reach 3 meters. This proved that nano copper conductive ink had a potential for RFID application.","PeriodicalId":6440,"journal":{"name":"2011 International Symposium on Advanced Packaging Materials (APM)","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2011-12-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"90636687","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 : 2011-12-19DOI: 10.1109/ISAPM.2011.6105682
Tian Wen-chao, Cao Yanrong, Wang Hongming
A MEMS (Micro-Electro-Mechanical Systems) RF (Radio Frequency) switch with the low loss and high isolation is presented. The model of a reconfigurable patch antenna with K and Ku wave bands is set up. The reconfigurable antenna has two work frequencies by changing the topology structure with the RF switch. The bandwidth is expanded from 1.16% to 7.71% by adding two parasitic patches. The resonance frequencies are 20.1GHz and 12.5GHz, respectively. The gains of K and Ku wave bands are obtained.
{"title":"Analysis of reconfigurable antenna with K and Ku wave bands based on RF switch","authors":"Tian Wen-chao, Cao Yanrong, Wang Hongming","doi":"10.1109/ISAPM.2011.6105682","DOIUrl":"https://doi.org/10.1109/ISAPM.2011.6105682","url":null,"abstract":"A MEMS (Micro-Electro-Mechanical Systems) RF (Radio Frequency) switch with the low loss and high isolation is presented. The model of a reconfigurable patch antenna with K and Ku wave bands is set up. The reconfigurable antenna has two work frequencies by changing the topology structure with the RF switch. The bandwidth is expanded from 1.16% to 7.71% by adding two parasitic patches. The resonance frequencies are 20.1GHz and 12.5GHz, respectively. The gains of K and Ku wave bands are obtained.","PeriodicalId":6440,"journal":{"name":"2011 International Symposium on Advanced Packaging Materials (APM)","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2011-12-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"79203725","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 : 2011-12-19DOI: 10.1109/ISAPM.2011.6105700
W. Zhu, P. Lai, Shaohua Yang
Mechanical reliability of epoxy molding compounds in plastic packages of integrated circuits (IC) is greatly affected by the compound ability to absorb moisture. In this paper, the hygro-thermal effect of a 2-layer stacked die package was investigated which emphasized on the hygroscopic stress and thermal mismatch stress. By finite element analysis (FEA), the distribution of moisture diffusion, thermo-mechanical stress, hygro-mechanical stress and hygro-thermo-mechanical stress under hygro-thermal environment were simulated and calculated. The simulation results showed that the bottom die-attach endured higher thermal stress after the moisture preconditioning under 85°C /85% RH. By simulation of hygroscopic swelling stress during reflow process, it was indicated that the critical position for the package reliability located at the corner of the bottom die and the interface between the bottom die-attach and die. Therefore, the reliability of the bottom layers is relatively low under hygro-thermal environment.
{"title":"Effect of hygro-thermo-mechanical stress on reliability of stacked die package","authors":"W. Zhu, P. Lai, Shaohua Yang","doi":"10.1109/ISAPM.2011.6105700","DOIUrl":"https://doi.org/10.1109/ISAPM.2011.6105700","url":null,"abstract":"Mechanical reliability of epoxy molding compounds in plastic packages of integrated circuits (IC) is greatly affected by the compound ability to absorb moisture. In this paper, the hygro-thermal effect of a 2-layer stacked die package was investigated which emphasized on the hygroscopic stress and thermal mismatch stress. By finite element analysis (FEA), the distribution of moisture diffusion, thermo-mechanical stress, hygro-mechanical stress and hygro-thermo-mechanical stress under hygro-thermal environment were simulated and calculated. The simulation results showed that the bottom die-attach endured higher thermal stress after the moisture preconditioning under 85°C /85% RH. By simulation of hygroscopic swelling stress during reflow process, it was indicated that the critical position for the package reliability located at the corner of the bottom die and the interface between the bottom die-attach and die. Therefore, the reliability of the bottom layers is relatively low under hygro-thermal environment.","PeriodicalId":6440,"journal":{"name":"2011 International Symposium on Advanced Packaging Materials (APM)","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2011-12-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"73942199","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 : 2011-12-19DOI: 10.1109/ISAPM.2011.6105676
L. Guoguang, Huang Yun, Lei Zhifeng
The main failure mechanisms of high power diode lasers such as material defects, mirror damage and solder related failures as well as to methods which significantly suppress the occurrence of catastrophic failure and solder related failures are investigated in this paper. Meanwhile, in order to obtain the lifetime data of high power QCM cm-bar arrays, we have set up an automated diode array reliability experiment to examine the characteristics of high power QCW cm-bar arrays over time, and aging test results up to 2.0×109 shots at 25°C will be reported.
{"title":"Studies of the degradation mechanisms in high power diode lasers","authors":"L. Guoguang, Huang Yun, Lei Zhifeng","doi":"10.1109/ISAPM.2011.6105676","DOIUrl":"https://doi.org/10.1109/ISAPM.2011.6105676","url":null,"abstract":"The main failure mechanisms of high power diode lasers such as material defects, mirror damage and solder related failures as well as to methods which significantly suppress the occurrence of catastrophic failure and solder related failures are investigated in this paper. Meanwhile, in order to obtain the lifetime data of high power QCM cm-bar arrays, we have set up an automated diode array reliability experiment to examine the characteristics of high power QCW cm-bar arrays over time, and aging test results up to 2.0×109 shots at 25°C will be reported.","PeriodicalId":6440,"journal":{"name":"2011 International Symposium on Advanced Packaging Materials (APM)","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2011-12-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"89541873","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 : 2011-12-19DOI: 10.1109/ISAPM.2011.6105698
Yao-Ling Kuo, Kwang-Lung Lin
The interfacial interaction between liquid eutectic Sn9Zn solder and electroplated Ni layer was investigated in the temperatures range of 230 ∼ 290°C. The interaction gives rise to various Ni-Zn intermetallic compounds, Ni5Zn21 and NiZn3, and Ni-Zn solid solution layer. The evolution of these layers is temperature dependent. The thickness of the interfacial reaction layer was measured with respect to reaction temperature and reaction time. The growth behavior of the interfacial layer and the activation energy of the interaction were discussed. The reaction mechanism was found to vary with respect to reaction temperature.
{"title":"The kinetics of interfacial interaction between eutectic Sn9Zn solder and nickel plating","authors":"Yao-Ling Kuo, Kwang-Lung Lin","doi":"10.1109/ISAPM.2011.6105698","DOIUrl":"https://doi.org/10.1109/ISAPM.2011.6105698","url":null,"abstract":"The interfacial interaction between liquid eutectic Sn9Zn solder and electroplated Ni layer was investigated in the temperatures range of 230 ∼ 290°C. The interaction gives rise to various Ni-Zn intermetallic compounds, Ni5Zn21 and NiZn3, and Ni-Zn solid solution layer. The evolution of these layers is temperature dependent. The thickness of the interfacial reaction layer was measured with respect to reaction temperature and reaction time. The growth behavior of the interfacial layer and the activation energy of the interaction were discussed. The reaction mechanism was found to vary with respect to reaction temperature.","PeriodicalId":6440,"journal":{"name":"2011 International Symposium on Advanced Packaging Materials (APM)","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2011-12-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"91512127","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 : 2011-12-19DOI: 10.1109/ISAPM.2011.6105740
Ge Dandong, C. Meng, Koh Liang Kng Ian, M. Walter
This report discloses an advanced approach to improve the prediction of electronic IC packages' reliability performance by studying packaging materials' thermo-mechanical properties at different high temperature storage conditions. Package level reliability has been well studied. However, during material screening stage, it is difficult to estimate the impact of IC packaging materials on package reliability performance based on typical material properties such as CTE, Tg and Storage Modulus determined at time zero stage. In this study, 3 types of Epoxy mold compounds (EMCs) were characterized with their thermo-mechanical properties by means of TGA, TMA and DMA at different 175°C high temperature storage (HTS) durations, i.e. 0hr, 1000hrs and 2000hrs respectively. Furthermore, simulation assessments for package stress are conducted for EMC evaluation at package level. The thermo-mechanical properties of EMC materials obtained are used as inputs for static linear simulation. Package stresses are retrieved from the simulation for relative comparison. The simulation results clearly show that the material degradation due to HTS has significant impact on the package stress level especially at high temperature range, which is critical for packages with stringent reliability requirement in automotive industry.
{"title":"A comparison study of thermal aging effect on mold compound and its impact on leadframe packages stress","authors":"Ge Dandong, C. Meng, Koh Liang Kng Ian, M. Walter","doi":"10.1109/ISAPM.2011.6105740","DOIUrl":"https://doi.org/10.1109/ISAPM.2011.6105740","url":null,"abstract":"This report discloses an advanced approach to improve the prediction of electronic IC packages' reliability performance by studying packaging materials' thermo-mechanical properties at different high temperature storage conditions. Package level reliability has been well studied. However, during material screening stage, it is difficult to estimate the impact of IC packaging materials on package reliability performance based on typical material properties such as CTE, Tg and Storage Modulus determined at time zero stage. In this study, 3 types of Epoxy mold compounds (EMCs) were characterized with their thermo-mechanical properties by means of TGA, TMA and DMA at different 175°C high temperature storage (HTS) durations, i.e. 0hr, 1000hrs and 2000hrs respectively. Furthermore, simulation assessments for package stress are conducted for EMC evaluation at package level. The thermo-mechanical properties of EMC materials obtained are used as inputs for static linear simulation. Package stresses are retrieved from the simulation for relative comparison. The simulation results clearly show that the material degradation due to HTS has significant impact on the package stress level especially at high temperature range, which is critical for packages with stringent reliability requirement in automotive industry.","PeriodicalId":6440,"journal":{"name":"2011 International Symposium on Advanced Packaging Materials (APM)","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2011-12-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"87430413","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 : 2011-12-19DOI: 10.1109/ISAPM.2011.6105737
Shufeng Zhao
The moisture absorption experiments of 8 kinds of molding compound and two kinds of organic substrate at 30°C/60% RH was performed to evaluate the moisture absorption performance. Organic substrate absorbed more moisture than molding compound, which provides validation of baking process before die attach during assembly, and possible cause of inter-layer popcorn during ball attach or solder reflow of some laminated substrate device. Influence of resin type and filler content on moisture absorption of molding compound was analyzed. Occurrence of moisture in condensed state is assumed to be cause of non-Fickian diffusion of moisture, and simulation result with corrected diffusion coefficient showed good explanation to the experimental absorption curve.
{"title":"Moisture absorption of molding compound and organic substrate","authors":"Shufeng Zhao","doi":"10.1109/ISAPM.2011.6105737","DOIUrl":"https://doi.org/10.1109/ISAPM.2011.6105737","url":null,"abstract":"The moisture absorption experiments of 8 kinds of molding compound and two kinds of organic substrate at 30°C/60% RH was performed to evaluate the moisture absorption performance. Organic substrate absorbed more moisture than molding compound, which provides validation of baking process before die attach during assembly, and possible cause of inter-layer popcorn during ball attach or solder reflow of some laminated substrate device. Influence of resin type and filler content on moisture absorption of molding compound was analyzed. Occurrence of moisture in condensed state is assumed to be cause of non-Fickian diffusion of moisture, and simulation result with corrected diffusion coefficient showed good explanation to the experimental absorption curve.","PeriodicalId":6440,"journal":{"name":"2011 International Symposium on Advanced Packaging Materials (APM)","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2011-12-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"84535786","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 : 2011-12-19DOI: 10.1109/ISAPM.2011.6105686
L. Xu, X. H. Chen, X. J. Liu, Y. Yu, Y. R. Wu
The effects of dispersion states of carbon nanotubes on thermal conductivity and Micro-hardness of Multi-walled carbon nanotube (MWCNT) reinforced copper nanocomposites were investigated. The nanocomposites were fabricated in a novel method. It involves the synthesis of MWCNT-implanted copper composite spheres and the preparation of the MWCNT/copper bulk materials using vacuum hot pressing and hot rolling. The thermal conductivity of the composites with different concentration of MWCNTs were measured. Although the coefficient of thermal conductivity decreases with the increase of the MWCNT content, it is still high enough to be used as electronic packaging materials even the concentration of MWCNTS in the composite is up to 5 wt%. Furthermore, the microhardness of the nanocomposites are much higher than that of pure copper, which is ascribed to the good dispersion of the MWCNTs in matrix.
{"title":"Thermal conductivity and microhardness of MWCNTs/copper nanocomposites","authors":"L. Xu, X. H. Chen, X. J. Liu, Y. Yu, Y. R. Wu","doi":"10.1109/ISAPM.2011.6105686","DOIUrl":"https://doi.org/10.1109/ISAPM.2011.6105686","url":null,"abstract":"The effects of dispersion states of carbon nanotubes on thermal conductivity and Micro-hardness of Multi-walled carbon nanotube (MWCNT) reinforced copper nanocomposites were investigated. The nanocomposites were fabricated in a novel method. It involves the synthesis of MWCNT-implanted copper composite spheres and the preparation of the MWCNT/copper bulk materials using vacuum hot pressing and hot rolling. The thermal conductivity of the composites with different concentration of MWCNTs were measured. Although the coefficient of thermal conductivity decreases with the increase of the MWCNT content, it is still high enough to be used as electronic packaging materials even the concentration of MWCNTS in the composite is up to 5 wt%. Furthermore, the microhardness of the nanocomposites are much higher than that of pure copper, which is ascribed to the good dispersion of the MWCNTs in matrix.","PeriodicalId":6440,"journal":{"name":"2011 International Symposium on Advanced Packaging Materials (APM)","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2011-12-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"86678747","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 : 2011-12-19DOI: 10.1109/ISAPM.2011.6105749
S. Ito, T. Ogashiwa, Y. Kanehira, H. Ishida, S. Shoji, J. Mizuno
This paper describes wafer level vacuum packaging with sub-micron Au particles for MEMS (micro electro mechanical systems) applications. Low temperature bonding is indispensable for relevant MEMS packaging, and use of sub-micron Au particles are suitable for hermetic seal bonding. For the fabrication of hermetically sealed wafer level packaging, a base silicon wafer and a cap glass wafer were bonded at around 200°C. Before bonding, the surface of seal rings was observed with a laser microscope to investigate the effect of surface roughness for hermeticity. After bonding, bonded wafers were dipped in the hydrofluoroether for 30 min. As a result, surface flatness of Au particles contributed to achieve hermetic sealing. Double seal rings structures were also useful to realize hermetic sealing.
{"title":"Evaluations of low temperature bonding using Au sub-micron particles for wafer level MEMS packaging","authors":"S. Ito, T. Ogashiwa, Y. Kanehira, H. Ishida, S. Shoji, J. Mizuno","doi":"10.1109/ISAPM.2011.6105749","DOIUrl":"https://doi.org/10.1109/ISAPM.2011.6105749","url":null,"abstract":"This paper describes wafer level vacuum packaging with sub-micron Au particles for MEMS (micro electro mechanical systems) applications. Low temperature bonding is indispensable for relevant MEMS packaging, and use of sub-micron Au particles are suitable for hermetic seal bonding. For the fabrication of hermetically sealed wafer level packaging, a base silicon wafer and a cap glass wafer were bonded at around 200°C. Before bonding, the surface of seal rings was observed with a laser microscope to investigate the effect of surface roughness for hermeticity. After bonding, bonded wafers were dipped in the hydrofluoroether for 30 min. As a result, surface flatness of Au particles contributed to achieve hermetic sealing. Double seal rings structures were also useful to realize hermetic sealing.","PeriodicalId":6440,"journal":{"name":"2011 International Symposium on Advanced Packaging Materials (APM)","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2011-12-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"82841323","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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