Dewen Tian

Guizhou University

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Chunqing Wang

Northeast Agricultural University

Yanhong Tian

Harbin Institute of Technology

Shumei Cui

Harbin Institute of Technology

Huayuan Liu

State Key Laboratory of Vehicle NVH and Safety Technology

Sifang Zhao

Beijing Institute of Technology

Qiwei Xu

Chongqing University

Qianfan Zhang

Harbin Institute of Technology

Yaqing Wang

Beijing Institute of Mathematical Sciences and Applications

John H. Lau

Micron Corporation (United States)

Y.M. Cheung

Hong Kong Baptist University

Cooperative Institutions

Beihang University

Harbin Institute of Technology

ASM Pacific Technology (China)

ASM International

Chinese Academy of Sciences

Shanghai Jiao Tong University

Beijing Institute of Technology

University of Chinese Academy of Sciences

Shandong University

Nanjing University

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Fast Tunable Biological Fluorescence Detection Device with Integrable Liquid Crystal Filter

Crystals (2021)

Qing Yang Tong Sun Xinyu Wu Guangchao Cui Mengzheng Yang

Detecting a variety of biological samples accurately and swiftly in an integrated way is of great practical significance. Currently, biofluorescent spectrum detection still largely relies on microscopic spectrometers. In this study, we propose an integrable method to detect biofluorescent spectrums with designed liquid crystal tunable filter (LCTF), in order to identify typical biological samples such as cells and bacteria. Hela cells labeled with red and green fluorescent proteins and Pseudomonas with fluorescence wavelengths of 610 nm, 509 nm and 450 nm, respectively, are inspected. High-resolution (6 μm) biofluorescent results have been achieved, together with clear images of the Hela cell clusters and the Pseudomonas bacteria colonies. Biofluorescence signals can be detected at a high transmittance (above 80%), and the response time of the device can reach 20 ms or below. The proposed method has the potential to be integrated into a microfluidic system to detect and identify the biofluorescent signals as a high throughput, low-cost option, for both high resolution and large field observation applications.

HeLa

10.3390/cryst11030272

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Citations (3)

The construction and simulation of V2G system in micro-grid

International Conference on Electrical Machines and Systems (2011)

Shumei Cui Liu Xiao-fei Dewen Tian Qianfan Zhang Liwei Song

Vehicle-to-Grid (V2G) technology has caught people's attention. Applications of V2G in general Power Grid face some challenges. It is complicated to control, in need of large amounts of EVs and hard to realize in the short term. In this paper V2G is applied to micro-grid and V2G system is constructed based on a parking lot. The structure is proposed in which bidirectional AC/DC and bidirectional DC/DC converters share one common DC bus, and also the coordination control strategy is given. Meanwhile this paper presents a general micro-source model as well as a V2G model. Simulation of voltage regulation and renewable energy support is conducted and results prove the availability of proposed structure and control strategy. The work is meaningful to the control and operation for micro-grid and V2G.

Vehicle-to-Grid

10.1109/icems.2011.6073378

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Citations (33)

High quality & low thermal resistance eutectic flip chip LED bonding

Ngai-Sze Lam Chi‐Yung Lee Ming-Yeung Wan Dewen Tian Ming Li

Die attach process plays a key role in the thermal management of high power LED packages by governing the thermal resistance of the solder interfaces between the LED chips and the substrate materials. In this paper, comparison was made between the GaN based flip chip LED packages fabricated by (1) heated collet and (2) flux reflow eutectic die attach process. Thermal transient characteristics of the samples had been investigated based on the evaluation of the differential structure function and chip temperature measurement by infrared microscopy. It was shown that LEDs with higher void content would result in higher thermal resistance and chip temperature. Under high power operation at 6W, it was estimated that the junction temperature would exceed 80°C with void content 40%, which was at least 10°C higher comparing to that with void content 20%. Based on the result, LEDs samples bonded by heated collet die attach process had an average void content of 8.8% with 0.9% standard deviation, which were smaller comparing to the samples bonded by flux reflow die attach process (40% void content with standard deviation 20.5%). Due to the advantage of small void content control, it is possible to fabricate high power LED package with low thermal resistance, consistent and reliable die attach quality by using heated collet die attach process.

Void (composites)

Infrared microscopy

Eutectic bonding

10.1109/icept.2013.6756673

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Citations (5)

Effect of thermal aging on microstructure, shear and mechanical shock failures for solder ball bonding joint

Dewen Tian Hongtao Chen Chunqing Wang

The interfacial microstructure evolution between Sn-3.5Ag-0.75Cu solder ball and Au/Ni/Cu pad was investigated under as-bonded and thermal aging conditions. Moreover, the shear and mechanical shock tests were carried out to study the failure mechanisms. Results showed that only one intermetallic compound, fine needle-like AuSn ₄ was found at the solder/pad interface under as-bonded condition. After aging, Ag ₃ Sn appeared in the solder bulk as a particle-like or elongated structure. Meanwhile, the intermetallic compounds layer became flat and a quaternary intermetallic compound Cu-Sn-Ni-Au appeared between AuSn ₄ layer and Ni(NiFe) layer. In addition, parts of AuSn ₄ spalled into the solder bulk with long hour aging. In the shear test, the solder joint exhibited a ductile failure. While in the mechanical shock test, the cracks initiated at the right end of the horizontal pad and propagate through the interfaces between IMCs. Furthermore, the factors dominating the failure mode were investigated which consists of external force and stress distribution, interfacial reaction and strain rate

Thermal shock

Direct shear test

10.1109/icept.2005.1564653

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Citations (4)

“Cultural Exchanges” as a Pillar to the China-EU Relations

Research series on the Chinese dream and China's development path (2016)

Dewen Tian

Pillar

10.1007/978-981-10-1145-0_4

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Citations (2)

Numerical simulation of solder spreading and solidification during solder jet bumping process

Dewen Tian Chunqing Wang Yanhong Tian

A VOF model is developed to simulate the solder spreading and solidification during solder jet bumping process. This model is based on fixed mesh method, and accounts for the surface tension, wetting effects, and heat transfer with solidification. The visualizations of the transient impact processes are employed in order to compare and validate the numerical model presented. Results show the spreading and recoiling process coupled with the solidification leads to a final cone-shaped solder bump. The variation of gravitational potential energy in the impingement is too small to be neglected. The simulated results are in excellent agreement with the photographic images.

Bumping

Transient (computer programming)

10.1109/icept.2008.4607032

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Citations (0)

Effect of solidification on solder bump formation in solder jet process: Simulation and experiment

Transactions of Nonferrous Metals Society of China (2008)

Dewen Tian Chunqing Wang Yanhong Tian

10.1016/s1003-6326(08)60205-8

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Citations (21)

Modeling of Micropitch Shift of a Magnetoelectrical Sensor During Laser Solder Ball Bonding Process

IEEE Transactions on Advanced Packaging (2009)

Dewen Tian Chunqing Wang Yanhong Tian

With the development of optoelectronics and microelectromechanical systems (MEMS) packaging, laser soldering has become an extensively used interconnection technique in electronic manufacturing industry. Postsolder shift in assembling of such components is the most challenging issue to affect the packaging yields. To maintain a high coupling efficiency or accuracy, tight control of postsolder shift is required. In the present work, a 3-D thermal-mechanical coupled finite element model was developed to investigate the time-dependent pitch shift induced by the laser solder ball bonding process. This model accounted for the laser interaction, the heat conduction, the thermal induced deformation and the phase change of the solder and could reflect the actual laser soldering process. The modeling results show different deformation mechanisms in the prebumping and reflow processes. The pitch shift is mainly induced by the thermal shrinkage of solder. The pitch angles obtained from the finite element analysis are in good agreement with those from the measurement using laser goniometer.

Electronic Packaging

10.1109/tadvp.2008.2008634

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Citations (4)

Research on vehicle control strategy for electric variable transmission in HEV

Qiwei Xu Jianing Xu Dewen Tian

This paper focused on the vehicle control strategy for electric variable transmission in hybrid electric vehicle. The operation modes of hybrid electric vehicle based on electric variable transmission were analyzed, and the vehicle control strategy based on the logic thresholds was proposed, according to the power requirement, current vehicle speed, and SOC of battery. Then, the simulation model of hybrid electric vehicle based on electric variable transmission was built, and the simulation results demonstrate the feasibility of the proposed strategy.

Continuously variable transmission

10.1109/icems.2013.6754518

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Citations (1)

Warpage and Thermal Characterization of Fan-Out Wafer-Level Packaging

John H. Lau Ming Li Dewen Tian Nelson Fan Eric Kuah

In this study, the warpage and thermal performances of fan-out wafer-level packaging (FOWLP) are investigated. Emphasis is placed on the characterization of the effects of FOWLP important parameters, such as chip size, chip thickness, package/chip area ratio, epoxy molding compound (EMC), chip EMC cap, carrier material and thickness, and die-attach film, on the warpage after post mold cure (PMC) and backgrinding of the EMC. The simulation results are compared with the experimental measurements. Also, the thermal performance (junction-to-ambient thermal resistance) of FOWLP with various chip thicknesses is characterized. Finally, some FOWLP important parameters affecting the warpage and thermal performances are recommended.

Fan-out

Wafer-level packaging

Characterization

Wafer-scale integration

10.1109/ectc.2017.309

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Citations (42)