Pub Date : 2022-05-11DOI: 10.23919/ICEP55381.2022.9795586
Kyung-Yeol Kim, Eun-Sung Ha, Tae-Ho Noh, Seung-Boo Jung
Recently, high-temperature endurance bonding has been required for the increasing demands of SiC die attachment for SiC power modules. The TLPS process is one of the promising high-heat endurance bonding methods. The general TLPS process needs a long bonding time about 60 min. To decrease the bonding time, we applied ultrasonic vibration during the soldering process. The cavitation effect induced by ultrasonic vibration can accelerate the intermetallics formation reaction. Also, we conducted the die shear test to evaluate the mechanical property after the environmental reliability test. The ultrasonic-assisted soldered joints showed superior mechanical reliability after a high-temperature storage test.
{"title":"The transient liquid phase bonding by ultrasonic-assisted soldering of Cu contained Sn-58Bi solder paste for high-temperature packaging applications","authors":"Kyung-Yeol Kim, Eun-Sung Ha, Tae-Ho Noh, Seung-Boo Jung","doi":"10.23919/ICEP55381.2022.9795586","DOIUrl":"https://doi.org/10.23919/ICEP55381.2022.9795586","url":null,"abstract":"Recently, high-temperature endurance bonding has been required for the increasing demands of SiC die attachment for SiC power modules. The TLPS process is one of the promising high-heat endurance bonding methods. The general TLPS process needs a long bonding time about 60 min. To decrease the bonding time, we applied ultrasonic vibration during the soldering process. The cavitation effect induced by ultrasonic vibration can accelerate the intermetallics formation reaction. Also, we conducted the die shear test to evaluate the mechanical property after the environmental reliability test. The ultrasonic-assisted soldered joints showed superior mechanical reliability after a high-temperature storage test.","PeriodicalId":413776,"journal":{"name":"2022 International Conference on Electronics Packaging (ICEP)","volume":"22 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2022-05-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"130534174","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 : 2022-05-11DOI: 10.23919/ICEP55381.2022.9795618
M. Honda, T. Hatakeyama, S. Nakagawa, R. Kibushi, M. Ishizuka
As the heat generation density of electronic devices increases, thermal vias are inserted in the printed circuit board (PCB) to dissipate the heat efficiently. Although the effective thermal conductivity of the PCB is important for the thermal management of electronics, measuring the effective thermal conductivity is time-consuming. Therefore, to save time, we focused on the thermal network method and examined the effect of the contraction heat flow around the thermal via on the numerically analyzed effective thermal conductivity of the PCB. The results showed that the contraction heat flow caused by the thermal via affects the range of 7 mm, and the range should be taken care of to express the contraction heat flow appropriately.
{"title":"A Thermal Network Model of a Printed Circuit Board Considering the Thermal Contraction Flow Caused by Thermal Vias","authors":"M. Honda, T. Hatakeyama, S. Nakagawa, R. Kibushi, M. Ishizuka","doi":"10.23919/ICEP55381.2022.9795618","DOIUrl":"https://doi.org/10.23919/ICEP55381.2022.9795618","url":null,"abstract":"As the heat generation density of electronic devices increases, thermal vias are inserted in the printed circuit board (PCB) to dissipate the heat efficiently. Although the effective thermal conductivity of the PCB is important for the thermal management of electronics, measuring the effective thermal conductivity is time-consuming. Therefore, to save time, we focused on the thermal network method and examined the effect of the contraction heat flow around the thermal via on the numerically analyzed effective thermal conductivity of the PCB. The results showed that the contraction heat flow caused by the thermal via affects the range of 7 mm, and the range should be taken care of to express the contraction heat flow appropriately.","PeriodicalId":413776,"journal":{"name":"2022 International Conference on Electronics Packaging (ICEP)","volume":"106 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2022-05-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"128073361","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 : 2022-05-11DOI: 10.23919/ICEP55381.2022.9795399
X. Zhao, H. Mitsugi, I. Shohji, T. Kobayashi
In this study, the Cu joint with a new high Tg epoxy resin was used as the research object. Tensile test, fracture surface observation and XPS analysis for fracture surface were performed using Cu/resin joints after high temperature and high humidity aging treatment under different conditions. The effect of aging on the adhesion strength and fracture mode of the Cu/resin joint was investigated. The analyzed results indicated that the adhesion strength of Cu/resin joint decreased with an increase in the aging time and aging temperature. Fracture mainly occurred at the Cu/resin and partially occurred at the Cu oxide formed in the surface of Cu.
{"title":"Effect of High Temperature and High Humidity Environment on Adhesion Strength of High Tg Epoxy Resin and Copper Joint","authors":"X. Zhao, H. Mitsugi, I. Shohji, T. Kobayashi","doi":"10.23919/ICEP55381.2022.9795399","DOIUrl":"https://doi.org/10.23919/ICEP55381.2022.9795399","url":null,"abstract":"In this study, the Cu joint with a new high Tg epoxy resin was used as the research object. Tensile test, fracture surface observation and XPS analysis for fracture surface were performed using Cu/resin joints after high temperature and high humidity aging treatment under different conditions. The effect of aging on the adhesion strength and fracture mode of the Cu/resin joint was investigated. The analyzed results indicated that the adhesion strength of Cu/resin joint decreased with an increase in the aging time and aging temperature. Fracture mainly occurred at the Cu/resin and partially occurred at the Cu oxide formed in the surface of Cu.","PeriodicalId":413776,"journal":{"name":"2022 International Conference on Electronics Packaging (ICEP)","volume":"86 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2022-05-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"127450809","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 : 2022-05-11DOI: 10.23919/ICEP55381.2022.9795471
T. Kobayashi, A. Kogure, I. Shohji
We focused on low-cost and high-strength cellulose nanofibers (CNFs) as a substitute for Ag used for lead- free solder material. In this study, Sn/conductive CNF composite plating film was formed on a Cu plate after the CNFs were given electrical conductivity by sulfide reduction treatment. After plating, two Cu plates with the Sn/conductive CNF composite plating film were heated and joined to investigate the microstructure of the solder joint. It was found that conductive CNFs were incorporated into Sn plating films, while after joining, the conductive CNFs were agglomerated due to the melting of Sn.
{"title":"Development of Sn Solder Plating Containing Cellulose Nanofiber","authors":"T. Kobayashi, A. Kogure, I. Shohji","doi":"10.23919/ICEP55381.2022.9795471","DOIUrl":"https://doi.org/10.23919/ICEP55381.2022.9795471","url":null,"abstract":"We focused on low-cost and high-strength cellulose nanofibers (CNFs) as a substitute for Ag used for lead- free solder material. In this study, Sn/conductive CNF composite plating film was formed on a Cu plate after the CNFs were given electrical conductivity by sulfide reduction treatment. After plating, two Cu plates with the Sn/conductive CNF composite plating film were heated and joined to investigate the microstructure of the solder joint. It was found that conductive CNFs were incorporated into Sn plating films, while after joining, the conductive CNFs were agglomerated due to the melting of Sn.","PeriodicalId":413776,"journal":{"name":"2022 International Conference on Electronics Packaging (ICEP)","volume":"96 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2022-05-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"127087593","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 : 2022-05-11DOI: 10.23919/ICEP55381.2022.9795457
J. A. Goundar, Ken Suzuki, H. Miura
The ribbon width dependency of graphene nanoribbons (GNR) on the electronic properties showed promising applications in the development of advanced photonic devices, such as multi-bandgap photovoltaic devices. However, large periodic oscillations due to the change in the number of carbon atoms is a major limitation. To effectively control the electronic band properties of the fabricated GNR-based device, in this study, application of strain to the GNR’s is proposed. This study experimentally validates the theoretical concept on an 80-nm ribbon width dumbbell-shaped-GNR structure. The device showed about clear change in the electronic properties under 3 different strain conditions with an observed gauge factor of about 1500. Under an irradiation of a focused laser beam, the device showed an improvement of about 4.5 times under applied strain when compared to an unstrained sample.
{"title":"Strain-Induced Change in the Photonic Properties of Dumbbell-Shaped Graphene Nanoribbon Structures","authors":"J. A. Goundar, Ken Suzuki, H. Miura","doi":"10.23919/ICEP55381.2022.9795457","DOIUrl":"https://doi.org/10.23919/ICEP55381.2022.9795457","url":null,"abstract":"The ribbon width dependency of graphene nanoribbons (GNR) on the electronic properties showed promising applications in the development of advanced photonic devices, such as multi-bandgap photovoltaic devices. However, large periodic oscillations due to the change in the number of carbon atoms is a major limitation. To effectively control the electronic band properties of the fabricated GNR-based device, in this study, application of strain to the GNR’s is proposed. This study experimentally validates the theoretical concept on an 80-nm ribbon width dumbbell-shaped-GNR structure. The device showed about clear change in the electronic properties under 3 different strain conditions with an observed gauge factor of about 1500. Under an irradiation of a focused laser beam, the device showed an improvement of about 4.5 times under applied strain when compared to an unstrained sample.","PeriodicalId":413776,"journal":{"name":"2022 International Conference on Electronics Packaging (ICEP)","volume":"124 14","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2022-05-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"113945270","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 : 2022-05-11DOI: 10.23919/ICEP55381.2022.9795648
Emiri Kato, R. Ishimatsu, J. Mizuno, T. Kasahara
We propose a green microfluidic electrogenerated chemiluminescence (ECL) device using 9,10-diphenylanthracene (DPA), which is one of the most studied deep-blue ECL material, as a host material. The ECL solution was prepared by dissolving DPA in an organic solvent along with green guest and assist dopant materials. 5,12-Dibutyl-1,3,8,10-tetramethylquinacridone (TMDBQA) was used as the gust, while 4,4’-bis[4-(diphenylamino)- styryl]biphenyl (BDAVBi) was used as the assist dopant. The microfluidic device with the prepared solution exhibited bright green emission. The obtained ECL spectrum was found to be almost identical to the photoluminescence spectrum of TMDBQA, and no significant contributions from DPA and BDAVBi were observed in the spectrum. We expect that the DPA host solution is promising for the fabrication of highly luminescent ECL devices.
{"title":"Green Microfluidic Electrogenerated Chemiluminescence Device Using 9,10-Diphenylanthracene as a Host Material","authors":"Emiri Kato, R. Ishimatsu, J. Mizuno, T. Kasahara","doi":"10.23919/ICEP55381.2022.9795648","DOIUrl":"https://doi.org/10.23919/ICEP55381.2022.9795648","url":null,"abstract":"We propose a green microfluidic electrogenerated chemiluminescence (ECL) device using 9,10-diphenylanthracene (DPA), which is one of the most studied deep-blue ECL material, as a host material. The ECL solution was prepared by dissolving DPA in an organic solvent along with green guest and assist dopant materials. 5,12-Dibutyl-1,3,8,10-tetramethylquinacridone (TMDBQA) was used as the gust, while 4,4’-bis[4-(diphenylamino)- styryl]biphenyl (BDAVBi) was used as the assist dopant. The microfluidic device with the prepared solution exhibited bright green emission. The obtained ECL spectrum was found to be almost identical to the photoluminescence spectrum of TMDBQA, and no significant contributions from DPA and BDAVBi were observed in the spectrum. We expect that the DPA host solution is promising for the fabrication of highly luminescent ECL devices.","PeriodicalId":413776,"journal":{"name":"2022 International Conference on Electronics Packaging (ICEP)","volume":"56 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2022-05-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"127702778","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 : 2022-05-11DOI: 10.23919/ICEP55381.2022.9795548
M. Kaneko, Kenji Takeda, M. Aibara, F. Uchikoba
This paper proposes a MEMS (Micro Electro Mechanical Systems) turbine as an organic Rankine cycle (ORC) system for an IoT (Internet of Things) edge device. The developing turbine shows millimeter scale, and it employs a low-boiling-point material as a working fluid. Therefore, this ORC system can harvest the low temperature waste heat energy. The developed MEMS turbine showed power generation with a winding wire 3-phase coil. When the heating temperature was 80 degree Celsius, the pressure was 0.28 MPa, the rotational speed was 109,090 rpm. The maximum output power was 968.5 micro VA when a load resistance was 0.5 ohm at each coil.
{"title":"Development of MEMS Structures for Miniature Organic Rankine Cycle System","authors":"M. Kaneko, Kenji Takeda, M. Aibara, F. Uchikoba","doi":"10.23919/ICEP55381.2022.9795548","DOIUrl":"https://doi.org/10.23919/ICEP55381.2022.9795548","url":null,"abstract":"This paper proposes a MEMS (Micro Electro Mechanical Systems) turbine as an organic Rankine cycle (ORC) system for an IoT (Internet of Things) edge device. The developing turbine shows millimeter scale, and it employs a low-boiling-point material as a working fluid. Therefore, this ORC system can harvest the low temperature waste heat energy. The developed MEMS turbine showed power generation with a winding wire 3-phase coil. When the heating temperature was 80 degree Celsius, the pressure was 0.28 MPa, the rotational speed was 109,090 rpm. The maximum output power was 968.5 micro VA when a load resistance was 0.5 ohm at each coil.","PeriodicalId":413776,"journal":{"name":"2022 International Conference on Electronics Packaging (ICEP)","volume":"133 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2022-05-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124021028","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 : 2022-05-11DOI: 10.23919/ICEP55381.2022.9795447
M. Koh, Kazuyoshi Yoneda, Kazutaka Nakada, Shoya Sekiguchi, Shoko Mishima, N. Ishikawa, T. Ogata
We have developed novel thermosetting low Dk/Df film for 5G application by using novel curable PPE. It showed low Dk, 3.1 at 10GHz, and low Df, 0.001 at 10GHz, high Tg, 200°C, low CTE, 18ppm and low water absorption 0.04%. And it showed good laser via process ability and good adhesion to Electroless plated Cu. We have made stacked substrate with L/S=15μm/15μm comb electrode and B-HAST test was conducted, and it showed good endurance. Transmission loss of the film was better than that of existing epoxy type low Df film.
{"title":"Novel thermosetting low Dk/Df film and its performance","authors":"M. Koh, Kazuyoshi Yoneda, Kazutaka Nakada, Shoya Sekiguchi, Shoko Mishima, N. Ishikawa, T. Ogata","doi":"10.23919/ICEP55381.2022.9795447","DOIUrl":"https://doi.org/10.23919/ICEP55381.2022.9795447","url":null,"abstract":"We have developed novel thermosetting low Dk/Df film for 5G application by using novel curable PPE. It showed low Dk, 3.1 at 10GHz, and low Df, 0.001 at 10GHz, high Tg, 200°C, low CTE, 18ppm and low water absorption 0.04%. And it showed good laser via process ability and good adhesion to Electroless plated Cu. We have made stacked substrate with L/S=15μm/15μm comb electrode and B-HAST test was conducted, and it showed good endurance. Transmission loss of the film was better than that of existing epoxy type low Df film.","PeriodicalId":413776,"journal":{"name":"2022 International Conference on Electronics Packaging (ICEP)","volume":"8 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2022-05-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124090060","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}
This study conducts power loss estimation of a silicon carbide (SiC) metal-oxide-semiconductor field-effect transistor (MOSFET) inverter in 1200V 200A power module during space-vector pulse width modulation (SVPWM) load operation using a fully integrated electromagnetic (EM)-circuit simulation. The focus of this study is placed on the switching transients of the SiC power MOSFET devices and the power losses of the SiC MOSFET inverter, including switching, conduction, diode, and reverse recovery losses. In addition, the effect of the parasitic inductances and capacitances of the SiC inverter on the switching transients and power losses are taken into account, and the values of which are calculated through Q3D Extractor under a working frequency of 1 MHz. The simulated parasitic inductances and switching waveforms are verified by the DPT experiment according to the IEC criterion. Moreover, an integrated circuit model of the SiC inverter is built to perform SVPWM switching at 400V drain bias and 30A load current, where the switching frequency and duty cycle are 15 kHz and 66%, respectively. Finally, the switching frequency effect on the power losses of the SiC inverter during load cycles is examined through parametric analysis.
{"title":"Estimation of Switching Transients and Power Losses of SiC-based Power MOSFET Inverter Using Electromagnetic-circuit Co-simulation during Six-step Commutation","authors":"Yan-Cheng Liu, Hsien-Chie Cheng, Hsin-Han Lin, Shian-Chiau Chiou, Shengyu Wu, T. Chang","doi":"10.23919/ICEP55381.2022.9795500","DOIUrl":"https://doi.org/10.23919/ICEP55381.2022.9795500","url":null,"abstract":"This study conducts power loss estimation of a silicon carbide (SiC) metal-oxide-semiconductor field-effect transistor (MOSFET) inverter in 1200V 200A power module during space-vector pulse width modulation (SVPWM) load operation using a fully integrated electromagnetic (EM)-circuit simulation. The focus of this study is placed on the switching transients of the SiC power MOSFET devices and the power losses of the SiC MOSFET inverter, including switching, conduction, diode, and reverse recovery losses. In addition, the effect of the parasitic inductances and capacitances of the SiC inverter on the switching transients and power losses are taken into account, and the values of which are calculated through Q3D Extractor under a working frequency of 1 MHz. The simulated parasitic inductances and switching waveforms are verified by the DPT experiment according to the IEC criterion. Moreover, an integrated circuit model of the SiC inverter is built to perform SVPWM switching at 400V drain bias and 30A load current, where the switching frequency and duty cycle are 15 kHz and 66%, respectively. Finally, the switching frequency effect on the power losses of the SiC inverter during load cycles is examined through parametric analysis.","PeriodicalId":413776,"journal":{"name":"2022 International Conference on Electronics Packaging (ICEP)","volume":"20 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2022-05-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"116939673","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 : 2022-05-11DOI: 10.23919/ICEP55381.2022.9795532
Z. Chen, N. Araki, Y. Kim, T. Fukuda, K. Sakui, T. Nakamura, T. Kobayashi, T. Obara, T. Ohba
To clarify the impact of backside defects on the device characteristics during wafer ultra-thinning, 20 nm-node DRAM Si wafers were thinned down to a thickness of 3-5 μm and evaluated. The dependences of the DRAM characteristics on the depth of backside defects, Si thickness, and chip position within a 300-mm wafer are described.
{"title":"Impact of Backside Defects on Device Characteristics of Ultra-Thin DRAMs with 3-5 μm Si Wafers for Bumpless Build Cube (BBCube) Application","authors":"Z. Chen, N. Araki, Y. Kim, T. Fukuda, K. Sakui, T. Nakamura, T. Kobayashi, T. Obara, T. Ohba","doi":"10.23919/ICEP55381.2022.9795532","DOIUrl":"https://doi.org/10.23919/ICEP55381.2022.9795532","url":null,"abstract":"To clarify the impact of backside defects on the device characteristics during wafer ultra-thinning, 20 nm-node DRAM Si wafers were thinned down to a thickness of 3-5 μm and evaluated. The dependences of the DRAM characteristics on the depth of backside defects, Si thickness, and chip position within a 300-mm wafer are described.","PeriodicalId":413776,"journal":{"name":"2022 International Conference on Electronics Packaging (ICEP)","volume":"16 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2022-05-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"125367375","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}
京公网安备 11010802042870号
京ICP备2023020795号-1
扫码关注我们
求助内容：
应助结果提醒方式：