Pub Date : 2018-09-01DOI: 10.1109/ESTC.2018.8546477
G. Arutinov, M. Giesbers, S. V. W. V. Doorn, F. Chiappini, R. Kusters, J. V. D. Brand
This paper reports the use of Laser-induced Forward Transfer (LIFT) technology for printing of multilayer flexible circuitries and the fabrication of micro-bumps for flip-chip bonding of packaged LEDs and bare die microcomponents. Bonding of passive and functional surface mount devices (SMD) on low-temperature polyethylene terephthalate (PET) foils have been demonstrated using two selective bonding techniques. Firstly, using a high intensity near-infrared (NIR) lamp, a bare die NFC chip was bonded on micro-bumps formed with LIFT printed isotropic conductive adhesive (ICA) within less than a minute. Secondly, using a high intensity Xenon lamp, passive components and packaged LEDs were bonded within 5 seconds on microbumps formed with conventional Sn–Ag–Cu (SAC) lead-free alloys. In the both cases, due to selective light absorption, a limited temperature increase was observed in the PET substrates allowing successful bonding of components onto the delicate polyethylene foil substrates using conventional interconnect materials.
{"title":"Integration with Light","authors":"G. Arutinov, M. Giesbers, S. V. W. V. Doorn, F. Chiappini, R. Kusters, J. V. D. Brand","doi":"10.1109/ESTC.2018.8546477","DOIUrl":"https://doi.org/10.1109/ESTC.2018.8546477","url":null,"abstract":"This paper reports the use of Laser-induced Forward Transfer (LIFT) technology for printing of multilayer flexible circuitries and the fabrication of micro-bumps for flip-chip bonding of packaged LEDs and bare die microcomponents. Bonding of passive and functional surface mount devices (SMD) on low-temperature polyethylene terephthalate (PET) foils have been demonstrated using two selective bonding techniques. Firstly, using a high intensity near-infrared (NIR) lamp, a bare die NFC chip was bonded on micro-bumps formed with LIFT printed isotropic conductive adhesive (ICA) within less than a minute. Secondly, using a high intensity Xenon lamp, passive components and packaged LEDs were bonded within 5 seconds on microbumps formed with conventional Sn–Ag–Cu (SAC) lead-free alloys. In the both cases, due to selective light absorption, a limited temperature increase was observed in the PET substrates allowing successful bonding of components onto the delicate polyethylene foil substrates using conventional interconnect materials.","PeriodicalId":198238,"journal":{"name":"2018 7th Electronic System-Integration Technology Conference (ESTC)","volume":"55 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"123468596","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 : 2018-09-01DOI: 10.1109/ESTC.2018.8546466
A. Mazloum-Nejadari, M. Lederer, G. Khatibi, B. Czerny, L. Weiss, J. Nicolics
In this study, the results of simulative and experimental investigations regarding thermal cycling (TC) of a LQFP (Low Profile Quad Flat Exposed Pad) with embedded copper wire bonds are discussed. The focus of this study is to analyze cyclic thermal and mechanical loading at high plastic strain in the heat affected zone (HAZ) above the nail-head, which may lead to fatigue failure of wire bonds in the packages. Thereby, a comparison with multiaxial mechanical test results obtained in a previous study will be drawn [1]. Indeed, the lifetime diagrams for these two methods show a clear correlation. Convincing agreement was found on experimental and on theoretical level. The described accelerated test method can be used as a rapid test for the determination of the lifetimes of wire bonds at various positions on the chip. Moreover, our testing method leads to conclusions, which enable improvements of package design.
{"title":"Investigation on the Lifetime of Copper Wire Bonds in Electronic Packages under Thermal and Mechanical Cyclic Loading","authors":"A. Mazloum-Nejadari, M. Lederer, G. Khatibi, B. Czerny, L. Weiss, J. Nicolics","doi":"10.1109/ESTC.2018.8546466","DOIUrl":"https://doi.org/10.1109/ESTC.2018.8546466","url":null,"abstract":"In this study, the results of simulative and experimental investigations regarding thermal cycling (TC) of a LQFP (Low Profile Quad Flat Exposed Pad) with embedded copper wire bonds are discussed. The focus of this study is to analyze cyclic thermal and mechanical loading at high plastic strain in the heat affected zone (HAZ) above the nail-head, which may lead to fatigue failure of wire bonds in the packages. Thereby, a comparison with multiaxial mechanical test results obtained in a previous study will be drawn [1]. Indeed, the lifetime diagrams for these two methods show a clear correlation. Convincing agreement was found on experimental and on theoretical level. The described accelerated test method can be used as a rapid test for the determination of the lifetimes of wire bonds at various positions on the chip. Moreover, our testing method leads to conclusions, which enable improvements of package design.","PeriodicalId":198238,"journal":{"name":"2018 7th Electronic System-Integration Technology Conference (ESTC)","volume":"26 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"121399415","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 : 2018-09-01DOI: 10.1109/ESTC.2018.8546371
Sheng-Chi Hsieh, C. Kung, T. Lee, Hung-Yi Lin, Pao-Nan Lee, Chen-Chao Wang
In this paper, a high quality factor 3D-inductor has been demonstrated by 3D-IPD solutionwith tall Cu pillar. It can achieve $sim7$:1 aspect ratio vertical connection without expensive TSV or TGV process, and meet the demand of high quality value wafer level process. A maximum quality factor of 60-80 has been achieved for 3D inductors in this study. Moreover, the proposed structure has been adopted to RF diplexer design with 1.0mm*0.5mm size for WiFi applications. The result shows a great performance improvement of lower insertion loss (0.31dB and 0.70dB) and larger attenuation (28dB and 26dB) than 2DIPD diplexer. Based on the measurementresult, the proposed high aspect ratio tall Cu pillar technology has been verified on RF inductors and IPD diplexer, demonstrates good performance, and is a significant promise for commercial wireless radio system.
{"title":"High-Q 3D-IPD Diplexer with High Aspect Ratio Cu Pillar Inductor","authors":"Sheng-Chi Hsieh, C. Kung, T. Lee, Hung-Yi Lin, Pao-Nan Lee, Chen-Chao Wang","doi":"10.1109/ESTC.2018.8546371","DOIUrl":"https://doi.org/10.1109/ESTC.2018.8546371","url":null,"abstract":"In this paper, a high quality factor 3D-inductor has been demonstrated by 3D-IPD solutionwith tall Cu pillar. It can achieve $sim7$:1 aspect ratio vertical connection without expensive TSV or TGV process, and meet the demand of high quality value wafer level process. A maximum quality factor of 60-80 has been achieved for 3D inductors in this study. Moreover, the proposed structure has been adopted to RF diplexer design with 1.0mm*0.5mm size for WiFi applications. The result shows a great performance improvement of lower insertion loss (0.31dB and 0.70dB) and larger attenuation (28dB and 26dB) than 2DIPD diplexer. Based on the measurementresult, the proposed high aspect ratio tall Cu pillar technology has been verified on RF inductors and IPD diplexer, demonstrates good performance, and is a significant promise for commercial wireless radio system.","PeriodicalId":198238,"journal":{"name":"2018 7th Electronic System-Integration Technology Conference (ESTC)","volume":"34 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"125564295","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 : 2018-09-01DOI: 10.1109/ESTC.2018.8546410
M. Schulz, J. Keller, C. Vernier, M. Dressler, B. Wunderle
In this paper a review of the latest research on interfacial fracture mechanical properties is given, while using the Advanced Mixed-mode Bending fracture test (AMB). The reviewed studies confirm that the AMB is a fast and accurate test method, which uses the least amount of samples and generates a wide bandwidth of mode-mix-dependent critical energy release rates. The maximum reported mode-mix bandwidth is 115° while testing only three samples. The so-far tested interfaces are built by materials commonly used in products of the microelectronic and automotive electronics industries. These material combinations are epoxy based molding compound on copper lead frame, molding compound on printed circuit boards and thermoset-based adhesive attached to a low temperature co-fired ceramic (LTCC). Further, the latest status of the current used crack length determination method is given. Combining two approaches into a new method enables the usage of images for the crack tip detection in the experimental post processing. This method is predestined for a future automatization, but is also restricted to a certain quality of the specimen surface, like the contrast and focus of the recorded parts. Nevertheless, an exemplification is given and the results are discussed.
{"title":"Status and review of advanced mixed-mode bending fracture test (AMB)","authors":"M. Schulz, J. Keller, C. Vernier, M. Dressler, B. Wunderle","doi":"10.1109/ESTC.2018.8546410","DOIUrl":"https://doi.org/10.1109/ESTC.2018.8546410","url":null,"abstract":"In this paper a review of the latest research on interfacial fracture mechanical properties is given, while using the Advanced Mixed-mode Bending fracture test (AMB). The reviewed studies confirm that the AMB is a fast and accurate test method, which uses the least amount of samples and generates a wide bandwidth of mode-mix-dependent critical energy release rates. The maximum reported mode-mix bandwidth is 115° while testing only three samples. The so-far tested interfaces are built by materials commonly used in products of the microelectronic and automotive electronics industries. These material combinations are epoxy based molding compound on copper lead frame, molding compound on printed circuit boards and thermoset-based adhesive attached to a low temperature co-fired ceramic (LTCC). Further, the latest status of the current used crack length determination method is given. Combining two approaches into a new method enables the usage of images for the crack tip detection in the experimental post processing. This method is predestined for a future automatization, but is also restricted to a certain quality of the specimen surface, like the contrast and focus of the recorded parts. Nevertheless, an exemplification is given and the results are discussed.","PeriodicalId":198238,"journal":{"name":"2018 7th Electronic System-Integration Technology Conference (ESTC)","volume":"16 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129592371","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 : 2018-09-01DOI: 10.1109/ESTC.2018.8546381
Chiu Soon Wong, Sze Yee Tan, Changlong Tan
One of the key factors which can cause to a halt of a surface-mount-technology (SMT) assembly process is due to the broken cover tape. Under such circumstances, the quality of the cover tape will need to be re-evaluated and confirmed by failure analysis, in particularly, the thickness of the cover tape. For the characterisation of flexible type material like cover tape, caliper, physical cross-section and optical techniques are some of the commonly used conventional techniques. However, destructive sample preparations are usually needed for these techniques, and the characterisation of the sample is confined to a very small region per sample preparation, therefore make them non-ideal. Profilometer is a more advanced technique that has been used widely in various applications but it has found to be not compatible for studying cover tape. In this work, we study the feasibility of using an interferometer in characterising the flexible type material through the investigation of various types of cover tapes from semiconductor industry. Results have demonstrated and verified that interferometer is a very promising technique in characterising flexible type material. This technique has enabled the characterisation of the material in 3-dimensional to an accuracy of <0.5 um non-destructively in a short amount of time as compared to the conventional techniques.
{"title":"Non-destructive Characterisation of Flexible Type Material using a White Light Interferometer","authors":"Chiu Soon Wong, Sze Yee Tan, Changlong Tan","doi":"10.1109/ESTC.2018.8546381","DOIUrl":"https://doi.org/10.1109/ESTC.2018.8546381","url":null,"abstract":"One of the key factors which can cause to a halt of a surface-mount-technology (SMT) assembly process is due to the broken cover tape. Under such circumstances, the quality of the cover tape will need to be re-evaluated and confirmed by failure analysis, in particularly, the thickness of the cover tape. For the characterisation of flexible type material like cover tape, caliper, physical cross-section and optical techniques are some of the commonly used conventional techniques. However, destructive sample preparations are usually needed for these techniques, and the characterisation of the sample is confined to a very small region per sample preparation, therefore make them non-ideal. Profilometer is a more advanced technique that has been used widely in various applications but it has found to be not compatible for studying cover tape. In this work, we study the feasibility of using an interferometer in characterising the flexible type material through the investigation of various types of cover tapes from semiconductor industry. Results have demonstrated and verified that interferometer is a very promising technique in characterising flexible type material. This technique has enabled the characterisation of the material in 3-dimensional to an accuracy of <0.5 um non-destructively in a short amount of time as compared to the conventional techniques.","PeriodicalId":198238,"journal":{"name":"2018 7th Electronic System-Integration Technology Conference (ESTC)","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"128666405","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 : 2018-09-01DOI: 10.1109/ESTC.2018.8546435
M. Schaulin, M. Oppermann, T. Zerna
In recent years, the market volume for power electronics has grown steadily and the development was assisted by innovative packaging technologies. Increased productivity and profitability requirements demand continuous improvement of production processes. New or complementary solutions for inline-capable diagnostics are required and should comply with the quality, reliability and cost-effectiveness requirements of the present and the future. In the quality testing of modern power electronic assemblies, the junction between power semiconductor and substrate is a challenge. Today, process control of this junction is mainly based on X-ray inspection, but thermography seems to be a promising approach. It works contact-free, fast and can determine the thermal properties of the package.
{"title":"Thermographic inspection method for quality assessment of power semiconductors in the manufacture of power electronics modules","authors":"M. Schaulin, M. Oppermann, T. Zerna","doi":"10.1109/ESTC.2018.8546435","DOIUrl":"https://doi.org/10.1109/ESTC.2018.8546435","url":null,"abstract":"In recent years, the market volume for power electronics has grown steadily and the development was assisted by innovative packaging technologies. Increased productivity and profitability requirements demand continuous improvement of production processes. New or complementary solutions for inline-capable diagnostics are required and should comply with the quality, reliability and cost-effectiveness requirements of the present and the future. In the quality testing of modern power electronic assemblies, the junction between power semiconductor and substrate is a challenge. Today, process control of this junction is mainly based on X-ray inspection, but thermography seems to be a promising approach. It works contact-free, fast and can determine the thermal properties of the package.","PeriodicalId":198238,"journal":{"name":"2018 7th Electronic System-Integration Technology Conference (ESTC)","volume":"31 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"122363339","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 : 2018-09-01DOI: 10.1109/ESTC.2018.8546414
Giang M. Nghiem, K. Aasmundtveit, H. Kristiansen, M. Bazilchuk
Anisotropic conductive film (ACF) is used for finepitch bonding in liquid crystal display (LCD) packaging. The film is typically composed of 3-10 $mu$m conductive particles incorporated into an epoxy based film matrix.Smaller particles (e.g., 3 $mu$ m) are used to obtain a finerpitch, driven by a demand for higher resolution. Using smaller particlesleads to a reduction in the effective contact area resulting in an increasein the resistivity. Smaller particles also exhibit a reduced tolerance forvariations in the bond line thickness which may affects the repeatability of interconnects and reliability. In this paper, we investigate the relation ofparticle deformation to the resistance of both free particles(electromechanical test) and particles embedded in an adhesive film (ACF bonding). The presence of adhesive film has resulted in a much higherparticle contact resistance and affected interconnect repeatability. Theeffect of the adhesive film is strongly dependent on the bump surface topography, and a smooth surface tends to increase the contact resistance.
{"title":"Anisotropic Conductive Film (ACF) bonding: effect of interfaces on contact resistance","authors":"Giang M. Nghiem, K. Aasmundtveit, H. Kristiansen, M. Bazilchuk","doi":"10.1109/ESTC.2018.8546414","DOIUrl":"https://doi.org/10.1109/ESTC.2018.8546414","url":null,"abstract":"Anisotropic conductive film (ACF) is used for finepitch bonding in liquid crystal display (LCD) packaging. The film is typically composed of 3-10 $mu$m conductive particles incorporated into an epoxy based film matrix.Smaller particles (e.g., 3 $mu$ m) are used to obtain a finerpitch, driven by a demand for higher resolution. Using smaller particlesleads to a reduction in the effective contact area resulting in an increasein the resistivity. Smaller particles also exhibit a reduced tolerance forvariations in the bond line thickness which may affects the repeatability of interconnects and reliability. In this paper, we investigate the relation ofparticle deformation to the resistance of both free particles(electromechanical test) and particles embedded in an adhesive film (ACF bonding). The presence of adhesive film has resulted in a much higherparticle contact resistance and affected interconnect repeatability. Theeffect of the adhesive film is strongly dependent on the bump surface topography, and a smooth surface tends to increase the contact resistance.","PeriodicalId":198238,"journal":{"name":"2018 7th Electronic System-Integration Technology Conference (ESTC)","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"125463787","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 : 2018-09-01DOI: 10.1109/ESTC.2018.8546501
J. Štulík, T. Blecha
This paper deals with nitrogen dioxide gas sensor based on multi-wall carbon nanotubes functionalized by carboxyl groups. The carbon nanotubes were non-covalent modified by lead phthalocyanine. The modification showed improvement of important sensor properties. Sensitivity change is 50 % from original value under exposure to 10 ppm of nitrogen dioxide. The dynamic properties of sensor are much better in comparison with non-modified carbon nanotubes. Gas desorption was accelerated by UV illumination and desorption time is shortened to several seconds.
{"title":"Modified CNTs for NO2 detection","authors":"J. Štulík, T. Blecha","doi":"10.1109/ESTC.2018.8546501","DOIUrl":"https://doi.org/10.1109/ESTC.2018.8546501","url":null,"abstract":"This paper deals with nitrogen dioxide gas sensor based on multi-wall carbon nanotubes functionalized by carboxyl groups. The carbon nanotubes were non-covalent modified by lead phthalocyanine. The modification showed improvement of important sensor properties. Sensitivity change is 50 % from original value under exposure to 10 ppm of nitrogen dioxide. The dynamic properties of sensor are much better in comparison with non-modified carbon nanotubes. Gas desorption was accelerated by UV illumination and desorption time is shortened to several seconds.","PeriodicalId":198238,"journal":{"name":"2018 7th Electronic System-Integration Technology Conference (ESTC)","volume":"40 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"132489901","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 : 2018-09-01DOI: 10.1109/ESTC.2018.8546349
Jörg Meyer, Prathamesh Jayant Upasani, Steffen Bickel, I. Panchenko, M. Wolf
Nanoporous intermetallic compounds (IMCs) are a promising option for interconnects in 3D integration of various electronic components. These combine the high thermal and mechanical stability of Cu-Sn-SLID (solid-liquid interdiffusion) interconnects with a strongly reduced processing time. In this paper we address the influence of the flux on the nanostructure of the interconnects. The further dissolution of Sn from the already known lamellar network of Cu$_{mathbf{3}}$Sn is reported for the first time and analyzed in detail.
纳米多孔金属间化合物(IMCs)在各种电子元件的三维集成中是一种很有前途的互连选择。这些结合了cu - sn - slip(固液互扩散)互连的高热稳定性和机械稳定性，并大大缩短了加工时间。本文研究了磁通对互连体纳米结构的影响。本文首次报道了Cu$_{mathbf{3}}$Sn片层网络中Sn的进一步溶解，并对其进行了详细的分析。
{"title":"Flux-induced porous structures in Cu-SnAg solidliquid-interdiffusion microbump interconnects","authors":"Jörg Meyer, Prathamesh Jayant Upasani, Steffen Bickel, I. Panchenko, M. Wolf","doi":"10.1109/ESTC.2018.8546349","DOIUrl":"https://doi.org/10.1109/ESTC.2018.8546349","url":null,"abstract":"Nanoporous intermetallic compounds (IMCs) are a promising option for interconnects in 3D integration of various electronic components. These combine the high thermal and mechanical stability of Cu-Sn-SLID (solid-liquid interdiffusion) interconnects with a strongly reduced processing time. In this paper we address the influence of the flux on the nanostructure of the interconnects. The further dissolution of Sn from the already known lamellar network of Cu$_{mathbf{3}}$Sn is reported for the first time and analyzed in detail.","PeriodicalId":198238,"journal":{"name":"2018 7th Electronic System-Integration Technology Conference (ESTC)","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"132496102","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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