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Electronics system-Integration Technology Conference, ESTC

作者： Xu Wang Xia Zhang Johan Liu Yan Zhang Key Laboratory of Advanced Display and System Applications & SMIT Center Shanghai University Shanghai P.R.China Current address: SanDisk Semiconductor (Shanghai) Corporation Shanghai P.R. China Department of Microtechnology and Nanoscience Chalmers University of Technology Goteborg Sweden

In earlier work, radio frequency (RF) performance of flip-chip anisotropic conductive adhesive (ACA) joints has been studied both in experiments and simulations. Nowadays, coplanar waveguide (CPW) transmission lines are being used widely as its lower loss compared to conventional MS lines. In this paper, we studied RF performance of the ACA joints for CPW lines using the simulation software HFSS. Firstly, we investigated the high frequency performance by varying distance and number of ACA particles. It shows that the S11 parameter greatly deteriorated at the lower frequency band. To further study this phenomenon, we extracted the equivalent circuit. The extracted circuit value showed that when particle number increased, the electromagnetic interaction between each particles gradually dominant the overall performance. As a result, the mutual inductance increased the equivalent inductance, and the equivalent capacitances was also increased in the interconnect region. The particle distance was found to have little influence on the RF performance. Secondary, we studied the influences of resin compound (epoxy matrix) with different dielectric constant. Resin compound greatly influence the effective constant and impedance at the output port, thus induced impedance mismatch and slightly changed S11 response in the frequency range. Finally, we performed ANOVA analysis to evaluate the impact factors among ACA resin, joint height, signal to ground bump distance, conductor overlap and particle number. The dielectric constant of resin was found to be the most important factor in flip chip CPW-CPW ACA joints. Conductor overlap and ground to signal distance are still the two main factors. To optimize the performance, the dielectric constant of resin should be as lower as possible, and the conductor overlap length and ground to signal distance should be minimized. Moreover, particle number and bump height proved to have least effect. To achieve best performance, the particle numbe

关键词： Radio frequency Flip chip Coplanar waveguides Transmission lines Resins Dielectric constant Conductors Coplanar transmission lines Inductance Impedance

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Vibration and buckling of a carbon nanotube inserted with a carbon chain

Vibration and buckling of a carbon nanotube inserted with a ...

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International Conference on (ICEPT) Electronic Packaging Technology

作者： Zhili Hu X.M. Guo Johan Liu Key Laboratory of Advanced Display and System Applications Ministry of Education & SMIT Center School of Mechatronics Engineering and Automation Shanghai University Shanghai China Shanghai Institute of Applied Mathematics and Mechanics Shanghai University China SMIT Center & Bionano Systems Laboratory Department of Microtechnology and Nanoscience Chalmers University of Technology Gothenburg Sweden

An elastic string-elastic shell model is developed to study vibration behaviors of a carbon nanowire. The present model predicts that non-coaxial vibration between the C-chain and the innermost tube does not occur due to negligible bending rigidity of the C-chain. In addition, it is found that the C-chain has most significant effect on the lowest frequency associated with radial vibration mode for circumferential wave-number 2 (n=2). In particular, the effect of the C-chain on axisymmetric radial breathing frequencies (n=0) predicted by the present model is found to be in reasonable agreement with known experimental and modeling results available in the literature.

关键词： Electron tubes Mathematical model Vibrations Equations Strain Carbon Force

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Numerical investigation on the effect of filler distribution on effective thermal conductivity of thermal interface material

Numerical investigation on the effect of filler distribution...

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International Conference on (ICEPT) Electronic Packaging Technology

作者： Cong Yue Yan Zhang Johan Liu Zhaonian Cheng Jing-yu Fan Key Laboratory of Advanced Display and System Applications Ministry of Education & SMIT Center School of Mechatronics Engineering and Automation Shanghai University Shanghai China SMIT Center & Bionano Systems Laboratory Department of Microtechnology and Nanoscience Chalmers University of Technology Gothenburg Sweden Shanghai Institute of Applied Mathematics and Mechanics Shanghai University Shanghai China

Thermal interface materials have been widely adopted in the thermal management for electronics system. Most of the thermal interface materials are made of polymers with thermally conductive particles distributed inside to enhance the thermal conductivity. Thus it is essential to figure out the effective thermal conductivity of this composite material. In the present paper, a parameterized cubic cell model had been developed and implemented by the finite element method. The numerical simulations were carried out to investigate the effect of the filler distributions on the effective thermal conductivity of the thermal interface materials. The volume percentage loadings of the particles ranging from 13% to 74% had been considered, and different particle distribution patterns had also been analyzed. The simulation results were compared with the experimental data as well as other models. A fairly good agreement was obtained for the particle volume percentage loading under consideration, which verified the developed cubic cell model.

关键词： Thermal conductivity Conductivity Materials Mathematical model Electronic packaging thermal management Numerical models Finite element methods

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Effect of encapsulation on OLED characteristics with anisotropic conductive adhesive

Effect of encapsulation on OLED characteristics with anisotr...

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Electronics system-Integration Technology Conference, ESTC

作者： Yan Zhang Mans Andreasson Johan Liu Thorvald Andersson Hsuan-Yi Liao Itsuo Watanabe Key Laboratory of Advanced Display and System Applications Ministry of Education & SMIT Center School of Mechatronics Engineering and Automation Shanghai University Shanghai China Applied seminconductor Physics Department of Microtechnology and Nanoscience Chalmers University of Technology Gothenburg Sweden SMIT Center Bionano Systems Laboratory Department of Microtechnology and Nanoscience Chalmers University of Technology Gothenburg Sweden Advanced Interconnect Material Division Hitachi Chemical Company Limited Chikusei Ibaraki Japan

Organic light emitting devices (OLEDs) is one of the most potentially interesting display technologies in the flat panel display (FPD) field. This paper investigates the effects of OLED structures and a perimeter encapsulation to protect the OLED from atmospheric exposure. Firstly, the electric features of the OLED devices with and without a copper phtalocyanine layer were measured, and the one with the additional buffer layer showed a lower turn-on voltage. Then the OLED device sample was encapsulated with a glass cover bonded to the substrate with an adhesive matrix containing micro-particles. The samples were stored in ambient conditions, and the IV characteristics were studied with shelf-time as a parameter. The measurement results indicated that the encapsulation had a significant improvement on the device operation. After two weeks of storage the encapsulated samples showed less degradation and the current density at a given operating bias was about fifty percent higher than without encapsulation.

关键词： Encapsulation Organic light emitting diodes Anisotropic magnetoresistance Conductive adhesives Flat panel displays Protection Copper Atmospheric measurements Electric variables measurement Buffer layers

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Multi-chip integrated high-power white LED device on the multi-layer ceramic substrate

Multi-chip integrated high-power white LED device on the mul...

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Electronic Components and Technology Conference (ECTC)

作者： Luqiao Yin Weiqiao Yang Yansheng Guo Kejun Ma Shuzhi Li Mingfa Chen Jia Li Jianhua Zhang School of Mechatronics and Automation Shanghai University Shanghai China Key Laboratory of Advanced Display and System Applications Ministry of Education Shanghai China Shanghai Research Center of Engineering and Technology for Semiconductor Lighting Shanghai China Rainbow Optoelectronics Material Shanghai Company Limited Shanghai China Microelectronics Technology Institute of East China Shanghai University Shanghai China

In order to solve the thermal issue and improve the thermal resistance of LED, a device with multi-chip packaged on multi-layer composite ceramic substrate is successfully packaged. The top layer of the substrate is low temperature co-fire ceramic (LTCC), while the base layer is aluminum nitride (AINx) ceramic. 18 chips(one watt) are used in the device, and all of them are simultaneously packaged on a composite ceramic substrate which is 55 mm in length and 20 mm in width. The 18 chips are designed into two rows, and three chips in series for six parallels. At the same time the same chips are packaged on aluminum (Al) substrate and alumina (AlOx) substrate. After wire bonding photoelectric parameters of the three package modules are tested, the results show that the properties of the AINx-based package has the best performances, the thermal resistance of the device is far smaller than the other devices packed on the Al substrate and the AlOx substrate. After phosphor coatings the AINx-based multi-layer ceramic substrate package has 896.1 lm (43.4 lm/W) loading 350 milliampere (mA) to each chip, and has 1081.3 lm (35.4 lm/W) loading 500 mA. The multi-chip module has little light degradation adding 500 mA to each chip after working in the room temperature for one afternoon. At last the module is simulated by ANSYS software, the highest junction temperature of the chips in the module is about 70.8degC when 1.8 watts electric power is loaded to each chip, this temperature is far lower than 125degC which will damage the chip, and he highest simulation temperature of the aluminum heat slug is about 39.3degC. The temperature of the aluminum heat slug is about 41.0degC which is tested by thermocouple in the experiments, and it is closely to the simulation temperature 39.3degC. At last the relationship between pn-junction temperature and thermal conductivity coefficient of the silver (Ag) paste , the relationship between pn-junction temperatures and convection coefficient ha

关键词： Light emitting diodes Ceramics Temperature Packaging Thermal resistance Thermal conductivity Testing Aluminum nitride Wire Bonding

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Recent Progress of Carbon Nanotubes as Cooling Fins in Electronic Packaging

Recent Progress of Carbon Nanotubes as Cooling Fins in Elect...

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2008 International Conference on Electronic Packaging Technology & High Density Packaging (ICEPT-HDP 2008), vol.2

作者： Johan Liu Yifeng Fu Teng Wang SMIT Center & Bionano Systems Laboratory Department of Microtechnology and Nanoscience Chalmers University of Technology Gothenburg Sweden Key Laboratory of Advanced Display and System Applications and SMIT Center School of Automation and Mechanical Engineering Shanghai University Shanghai China

As power density in electronic system is approaching a level that conventional cooling methods can't handle, reliability of microsystems is of large concern. In this paper, novel schemes for heat dissipation on electrical components have been reviewed with a strong focus on using Carbon Nanotubes (CNTs) as cooling fins as a basic approach. With an extraordinary high thermal conductivity, CNT is considered as an ideal material for thermal management in high heat flux microsystems. Fabricated onto a silicon substrate to form microchannels, the CNT based cooling fins show high heat dissipation efficiency. This paper reviews the ongoing research on CNT based microchannel cooler development carried out so far. Both experimental and simulation results are included and presented.

关键词： Microchannel Cooling Arrays Thermal conductivity Carbon nanotubes Heating Heat transfer

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An adaptive and fast H.264 multi-frame selection algorithm based on information from previous searches

An adaptive and fast H.264 multi-frame selection algorithm b...

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IEEE International Conference onMultimedia and Expo, ICME 2007

作者： Liquan, Shen Zhi, Liu Zhaoyang, Zhang Xuli, Shi Key Lab. of Advanced Display and System Application Ministry of Education Shanghai University Shanghai 200072 China

ISBN: (纸本)1424410177

The H.264 video coding standard adopts multiple reference frames for motion estimation. This new feature improves the prediction accuracy of inter-coding blocks significantly, but it results in a considerable increase in encoder complexity, mainly regarding to multi-frame selection and motion estimation. The reference software JM adopts the full search scheme, and the increased computation is in proportion to the number of searched reference frames. However, the reduction of prediction residues is highly dependent on the nature of sequences, not on the number of searched frames. In this paper, we propose an adaptive and fast multi-frame selection algorithm (AFMFS) based on motion vectors and SAD information coming from previous searches to adaptively terminate the procedure of multiple reference frames selection. Compared with the full search algorithm and the flexible multi-reference frame search criterion (FMRFSC), simulation results show that the proposed algorithm can save 55.28% and 40.23% computation cost on average, respectively, while it still maintains similar coding efficiency. © 2007 IEEE.

关键词： Motion estimation

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Wigner-Ville distribution and cross Wigner-Ville distribution of noisy signals

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Journal of systems Engineering and Electronics 2008年第5期000卷

作者： Chen Guanghua Ma Shiwei Liu Ming Zhu Jingming Zeng Weimin Key Laboratory of Advanced Display and System Applications Ministry of Education & Microelectronic Research and Development CenterShanghai Univ.Shanghai 200072P.R.China

The Wigner-Ville distribution (WVD) and the cross Wigner-Ville distribution (XWVD) have been shown to be efficient in the estimation of instantaneous frequency (IF).But the statistical result of the IF estimation from XWVD peak is much better than using WVD *** reason is given from a statistical point of *** studies show that XWVD of the analyzed signal can be estimated from XWVD of the noise-contaminated *** estimation is unbiased,and the variance is equal to that of *** this case,WVD cannot be estimated from WVD of the noise-contaminated ***,higher SNR is required when WVD is used to analyze signals.

关键词： Wigner-Ville distribution cross Wigner-Ville distribution instantaneous frequency expectation vari-ance

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Performance analysis of region of interest video transmission system

Performance analysis of region of interest video transmissio...

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IET Conference on Wireless, Mobile and Sensor Networks 2007, CCWMSN'07

作者： Wang, Yongfang Zhang, Zhaoyang Liu, Zhi School of Communication and Information Engineering Shanghai University Shanghai 200072 China Key Laboratory of Advanced Display and System Application Ministry of Education Shanghai 200072 China

ISBN: (纸本)9780863418365

We investigate the video transmission efficiency of channel code, modulation mode and layered space time code for region of interest video transmission system. Excellent channel code achieves more coding gains, suitable modulation mode adaptively overcomes different channel fading and layered space time code achieves not only coding gain but only diversity gain. Based on the above analysis, we propose an adaptive video transmission system according to channel environment and video constructed quality require. We derive an analytic bound for the error probability, and conduct experiments for H.264 interest of region video streaming. It is shown that the proposed system enhances the PSNR performance of region of interest significantly by adaptive choice of channel code, modulation mode, and layered space time code in the wireless channel.

关键词： Modulation

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Blue organic light emitting diodes with graded junction

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Guangdianzi Jiguang/Journal of Optoelectronics Laser 2007年第8期18卷 893-895页

作者： Zhang, Hao Liu, Shan-Peng Huang, Wei Wei, Fu-Xiang Jiang, Xue-Yin Zhang, Zhi-Lin Key Laboratory of Advanced Display and System Application Department of Materials Science Shanghai University Shanghai 201800 China

A blue organic light emitting diode (OLED) with a graded junction (GJ) at hole transporting layer (HTL) and emitted layer (EML) interface was constructed. Compared with the conventional heterojunction (HJ) OLED, GJ OLED exhibited significantly improved stability, and the half lifetime achieved 6998 h at initial luminance 100 cd/m2, which is more than 6 times longer than that of HJ OLED. And a Gaq thin layer is inserted in the TBADN/Alq interface, the step barrier from Alq Gaq to TBADN for electron injection is though formed. The GJ devices with Gaq layer show 20% higher efficiency than that of conventional and 7 times longer lifetime than that of HJ one.

关键词： Organic light emitting diodes (OLED)

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