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Pressure-assisted large-area (50∗45 mm2) sintered-copper bonding for power modules

Materials Science in Semiconductor Processing 2025年 198卷

作者： Dongfang Dai Yexiong Huang Kai Zheng Jiabing Yu Xianping Chen College of Optoelectronic Engineering and Key Laboratory of Optoelectronic Technology & Systems Education Ministry of China Chongqing University 400044 Chongqing China School of Physics and Electronic Engineering Chongqing Normal University 401331 Chongqing China School of Electrical Engineering and State Key Laboratory of Power Transmission Equipment & System Security and New Technology Chongqing University 400044 Chongqing China

- In this study, we demonstrate a novel copper paste encapsulated with copper formate, enabling robust large-area bonding (50 × 45 mm 2 ) under remarkably mild conditions: middle pressure (10 ...

- In this study, we demonstrate a novel copper paste encapsulated with copper formate, enabling robust large-area bonding (50 × 45 mm 2 ) under remarkably mild conditions: middle pressure (10 MPa), rapid sintering (10 min), and low temperature (220 °C). A systematic investigation of the relationship between bonding strength and microstructural evolution is conducted . The bonded interface exhibits a low porosity of ∼10 % and achieves a bonding strength exceeding 60 MPa . Crucially, under pressures above 10 MPa , significant plastic deformation of the sintered copper is observed, accompanied by a marked reduction in surface roughness and a concomitant enhancement in bonding strength. Thermal simulations further indicate that the large-area sintered copper layer reduces the chip junction temperature by 6.6°C, highlighting its potential for thermal management applications. This breakthrough addresses the longstanding challenges of high energy consumption and inadequate bonding strength in large-scale sintering processes, offering a promising pathway for high-temperature applications in next-generation high-power devices. 1

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Research on Vibration Measurement and Characteristics of Converter Transformer Considering the Influence of Harmonics

Research on Vibration Measurement and Characteristics of Con...

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Electrical Engineering (CIYCEE), IEEE China International Youth Conference on

作者： Peiyu Jiang Zhanlong Zhang Zhicheng Pan State Key Laboratory of Power Transmission Equipment & System Security and New Technology (Chongqing University) Chongqing China Maintenance & Test Center of EHV Power Transmission Company China Southern Power Grid Guangzhou China

ISBN: (纸本)9781665400657

The vibration of the converter transformer is related to voltage and current. The high-voltage direct current transmission system contains a lot of harmonics, and the generated vibration and noise seriously affect its operating environment. The current research has not fully considered the impact of harmonics on vibration. In order to reveal the relationship between the two, this paper sets up a vibration measurement experiment, collects the vibration and voltage and current waveforms of the converter transformer box in operation, and analyzes the harmonic spectrum and the time-frequency characteristic distribution of vibration signals. The results prove that harmonics will shift the dominant frequency of vibration, and the valve-side voltage harmonics are one of the main causes of high-frequency vibration components. The research results provide a theoretical basis for the on-line diagnosis of vibration measurement technology and the suppression of vibration and noise.

关键词： Vibrations Time-frequency analysis Voltage measurement Windings Vibration measurement Transformer cores Harmonic analysis

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Mechanical Fault Diagnosis of Transformer On-Load Tap-Changer Based on Improved Variational Mode Decomposition and Support Vector Machine

Mechanical Fault Diagnosis of Transformer On-Load Tap-Change...

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International Conference on High Voltage Engineering and Application, ICHVE

作者： Hongrui Gu Youyuan Wang Bonan Li Yingyu Chen Zhihe Li State Key Laboratory of Power Transmission Equipment & System Security and New Technology Chongqing University Chongqing China

ISBN: (数字)9781728155111

ISBN: (纸本)9781728155128

Transformer on-load tap-changer (OLTC) is a key component of transformer. Vibration detection method can be applied to the mechanical condition monitoring and fault diagnosis owning to its non-invasive and high-sensitive property. However, several problems such as modal aliasing and feature one-sidedness exist in the current signal processing and fault diagnosis method for OLTC vibration signal. In the paper, an OLTC simulation experiment platform and a vibration signal sensor system are built, and three typical defects, including spring elasticity change, contact wear and contact looseness are set. The vibration signals collected by accelerometers are decomposed into a series of modal components with narrow band and distinguishing center frequency by improved variational mode decomposition (VMD). Then the features including energy, permutation entropy and singular values of each modal component are extracted, and Laplacian-score is used to select the features with better discriminative ability. Finally, the support vector machine (SVM) optimized by genetic algorithm (GA) is applied to fault diagnosis. The result shows that the proposed feature extraction method provides comprehensive and distinguishing features in each operation state, and the proposed fault diagnosis method has higher identification accuracy compared with conventional method.

关键词： Vibrations Feature extraction Support vector machines Fault diagnosis Time-frequency analysis Genetic algorithms Springs

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Study on Raman Spectroscopy Detection Method of Furfural in Transformer Oil Based on Microfluidic Chip

Study on Raman Spectroscopy Detection Method of Furfural in ...

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International Conference on High Voltage Engineering and Application, ICHVE

作者： Zhang Jiayi Chen Weigen Shi Haiyang Zhou Weiran Zhang Shuhua State Key Laboratory of Power Transmission Equipment and System Security and New Technology Chongqing University Chongqing China

ISBN: (数字)9781728155111

ISBN: (纸本)9781728155128

The content of dissolved furfural in oil is an important feature to determine the aging status of transformer insulation. Microfluidic chips are experimental devices that integrate chemical and biological analytical processes, including the synthesis, reaction, separation and detection onto one single microchip and complete the analysis. Moreover, Raman spectrum detection method of furfural in transformer oil based on microfluidic chip has very high sensitivity that could be easily used for monitoring environmental pollutants and biological analysis of samples. In this paper, a microfluidic chip has been designed. The intensity variation of the Raman characteristic peak of furfural reflects the concentration variation of furfural in oil. A direct measurement method of furfural Raman spectroscopy in oil based on microfluidic was established. The microfluidic Raman detection was carried out with deionized water as the dispersed phase, and the lowest concentration of furfural detected was 1.38 mg/L. It could be proved that the feasibility of microfluidic technology for in-situ detection of furfural Raman spectroscopy in oil, which laid the foundation for subsequent research.

关键词： Oils Microfluidics Oil insulation Power transformer insulation Bonding Standards Surface treatment

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Detection of Dissolved Gas in Transformer Oil Based on All-Optical Photoacoustic Spectroscopy

Detection of Dissolved Gas in Transformer Oil Based on All-O...

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International Conference on High Voltage Engineering and Application, ICHVE

作者： Tianhe Yang Weigen Chen State Key Laboratory of Power Transmission Equipment & System Security and New Technology Chongqing University Chongqing China

ISBN: (数字)9781728155111

ISBN: (纸本)9781728155128

The photoacoustic spectroscopy gas detection method is widely used in Dissolved Gas Analysis (DGA), which usually using a capacitive microphone as a signal detector. However, the electric nature of capacitive microphones limits the application in circumstances of electromagnetic interference. To reducing the shortcoming of anti-interference and enhancing sensitivity, this paper proposed a fiber-optic microphone instead of a capacitive microphone to detect the photoacoustic signal. The central wavelength of 1653.67 nm was used as the light source for methane acoustic excitation. The trace methane detection experiment demonstrates that, with the wavelength modulation spectrum and second-harmonic detection methods, the detection limit was achieved to be 130 ppb, which meets the requirements of indicator in Dissolved Gas Analysis.

关键词： Optical fiber sensors Spectroscopy Microphones Optical switches Gas lasers Optical fiber amplifiers Optical amplifiers

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Correction: 12-state multi-level cell storage implemented in a 128 Mb phase change memory chip

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Nanoscale 2021年第23期13卷 10608-10609页

作者： Zhitang Song Daolin Cai Yan Cheng Lei Wang Shilong Lv Tianjiao Xin Gaoming Feng State Key Laboratory of Functional Materials for Informatics Shanghai Institute of Micro-system and Information Technology Chinese Academy of Sciences Shanghai 200050 China. ztsong@*** caidl@***. Key Laboratory of Polar Materials and Devices (MOE) Department of Electronics East China Normal University Shanghai 200241 China. Semiconductor Manufacturing International Corporation Shanghai 201203 China.

Correction for '12-state multi-level cell storage implemented in a 128 Mb phase change memory chip' by Zhitang Song et al., Nanoscale, 2021, DOI: 10.1039/d1nr00100k.

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Multi-Dimension Harmonic Current Feedforward Compensation Control of AC-DC PFC Converter

Multi-Dimension Harmonic Current Feedforward Compensation Co...

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International Conference on Power Electronics and Motion Control (IPEMC)

作者： Qiwei Huang Weiguo Lu Shaoling Li Shengcai Liu State Key Laboratory of Power Transmission Equipment & System Security and New Technology Chongqing University Chongqing China

ISBN: (数字)9781728153018

ISBN: (纸本)9781728153025

Single-phase AC-DC power factor correction (PFC) converters have instantaneous input and output power imbalances, resulting in second harmonic components in the output voltage. Usually the external voltage loop is designed as a low-bandwidth mode, that is, a low-pass filter (LPF) is introduced to eliminate the influence of the output voltage harmonics on the reference current, which reduces the dynamic performance of the system. Different from the existing LPF harmonic influence suppression scheme, this paper proposes a multi-dimensional harmonic current feedforward compensation control scheme, which extracts the odd harmonics in the input current through a band-pass filter, and converts the odd harmonics in the input current into even harmonics by dq coordinate transformation wave. And the converted even harmonics are fed forward to cancel the even harmonics in the voltage outer loop, thereby suppressing the harmonic distortion of the reference current. Taking a single-phase Boost PFC circuit as an example, an experimental prototype was built and the feasibility verification of the proposed scheme was completed. The results show that compared with the traditional LPF scheme, the proposed scheme improves its dynamic response by about 70% while ensuring high-quality input current.

关键词： Prototypes Harmonic analysis Distortion Harmonic distortion Feedforward systems Voltage control Power harmonic filters

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Dual Data- and Knowledge-Driven Land Cover Mapping Framework for Monitoring Annual and Near-Real-Time Changes

SSRN

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SSRN 2024年

作者： Du, Zhenrong Yu, Le Arvor, Damien Li, Xiyu Cao, Xin Zhong, Liheng Zhao, Qiang Ma, Xiaorui Wang, Hongyu Liu, Xiaoxuan Zhang, Mingjuan Xu, Bing Gong, Peng School of Information and Communication Engineering Dalian University of Technology Dalian116024 China Department of Earth System Science Ministry of Education Key Laboratory for Earth System Modeling Institute for Global Change Studies Tsinghua University Beijing100084 China Ministry of Education Ecological Field Station for East Asian Migratory Birds Beijing100084 China Tsinghua University Department of Earth System Science Xi’an Institute of Surveying Mapping Joint Research Center for Next-Generation Smart Mapping Beijing100084 China CNRS Université Rennes 2 LETG UMR 6554 RennesF-35000 France State Key Laboratory of Remote Sensing Science Faculty of Geographical Science Beijing Normal University Beijing100875 China Ant Group Beijing100020 China Aerospace Information Research Institute Chinese Academy of Sciences Beijing100190 China College of Forestry Beijing Forestry University Beijing100083 China Department of Geography Department of Earth Sciences Institute for Climate and Carbon Neutrality University of Hong Kong 999077 Hong Kong

As one of the most important application for remote sensing monitoring, land cover mapping has witnessed notable advancements in data acquisition, algorithmic diversity, and classification accuracy. Despite the instrumental role data-driven algorithms have played in the development of global land cover products, their inherent limitations as "black box" methods often fall short of meeting end-users’ specific requirements. In this study, built upon the foundation of the earlier land cover mapping platform (FROM-GLC Plus, FGP), we bridge the gap between theoretical frameworks and practical applications by developing a dual-driven framework (FGP 2.0) that synergizes knowledge-based reasoning with data learning for intelligent remote sensing land cover mapping. By incorporating ontology-based semantic descriptions with advanced data-driven algorithms, FGP 2.0 provides the capacity for both traditional annual mapping and emerging dynamic mapping. For annual mapping, FGP 2.0 significantly improves the overall accuracy of data-driven FGP (improved by ~5%). For dynamic mapping, FGP 2.0 illustrates more precise land cover distribution and reliable changes compared to FGP and Dynamic World (DW), and an operational dynamic mapping tool has been developed on the Google Earth Engine (GEE). This innovative approach not only fulfills the current demand for reliable land cover maps but also sets a new benchmark for the integration of geoscientific expertise with machine learning techniques in environmental monitoring. © 2024, The Authors. All rights reserved.

关键词： Mapping

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IGBT Junction Temperature Measurement via Quasi-threshold Voltage Under Constant Current Source Driver

IGBT Junction Temperature Measurement via Quasi-threshold Vo...

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International Conference on Power Electronics and Motion Control (IPEMC)

作者： Kaihong Wang Luowei Zhou Pengju Sun Xiong Du State Key Laboratory of Power Transmission Equipment and System Security and New Technology Chongqing University Chongqing China

ISBN: (数字)9781728153018

ISBN: (纸本)9781728153025

Thermo-sensitive electrical parameter (TSEP) methods are widely applied in the junction temperature measurement of power semiconductor devices for reliability assessment. This paper proposes a method to measure junction temperatures of insulated-gate bipolar transistors (IGBTs) during the turn-on process. The quasi-threshold voltage is employed as an indicator of a TSEP to extract the junction temperature under constant current source (CCS) driver, utilizing the parasitic inductor between the Kelvin and power emitter terminals of an IGBT module. The relationship between the junction temperature and the quasi-threshold voltage is investigated. A dynamic switching characteristic test platform is established to experimentally verify the theoretical analysis. The experimental results show that the dependency between IGBT junction temperature and quasi-threshold voltage is close to linear but susceptible to bus voltage. Faint impact on junction temperature has been introduced by load current and bond wires lift-off. It can be concluded that quasi-threshold voltage under CCS driver is a potentially practical TSEP for online junction temperature measurement.

关键词： Temperature measurement Insulated gate bipolar transistors Temperature Voltage measurement Wires Junctions Monitoring

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Propagation Characteristics of Ultrasonic Signals Generated Partial Discharge in Transformer Oil

Propagation Characteristics of Ultrasonic Signals Generated ...

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Advanced Electrical Equipment and Reliable Operation (AEERO), International Conference on

作者： Guochao Qian Kejie Wu Jiali Lei Zhixian Zhang Yuxuan Song Weigen Chen State Key Laboratory of Power Transmission Equipment & System Security and New Technology Chongqing University Yunnan China Electric Power Research Institute of Yunnan Power Grid Co. Ltd. Yunnan China

ISBN: (纸本)9781665402651

To improve the ultrasonic detection’s sensitivity and positioning accuracy for partial discharge, reduce the attenuation of the ultrasonic signal received by the sensor, a small oil-filled tank platform was built and the ultrasonic signal propagation characteristics in transformer oil were studied based on this platform. The attenuation of ultrasonic signals at various frequencies under different distances, the barrier of insulating cardboard, and the barrier of winding are studied separately. The signal amplitude of 180kHz is attenuated to 6% of the amplitude of the reference position at the maximum experimental distance. The 200kHz signal is attenuated to less than 10% of the reference amplitude under the barrier of the insulating cardboard. Signals above 60kHz are attenuated to less than 20% of the reference amplitude when the winding is blocked. According to the research in this paper, the attenuation of high-frequency ultrasonic signals in transformer oil is stronger than that of low-frequency ultrasonic signals. This study provides a reference for the selection of the center frequency of the transformer built-in sensor and the layout of the sensor array.

关键词： Partial discharges Oils Windings Layout Crystals Oil insulation Attenuation

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