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Yan Zhou - One of the best experts on this subject based on the ideXlab platform.

  • pressureless bonding process using ag nanoparticle paste for flexible Electronics Packaging
    Scripta Materialia, 2012
    Co-Authors: Jianfeng Yan, Yan Zhou, Guisheng Zou, Jialie Ren, Jiuchun Yan
    Abstract:

    We have developed a new method for preparing a paste containing a high concentration of Ag nanoparticles for pressureless bonding. A nanoscale layer of polyvinylpyrrolidone coated on the nanoparticles prevents the coalescence of Ag nanoparticles. After heating in air, sintering and bonding occur after the decomposition of polyvinylpyrrolidone. Joint strengths were increased significantly using this new Ag nanoparticle paste as bonding material. Robust joints with shear strength above 20 MPa were formed even without additional bonding pressure.

  • Low temperature sintering of Ag nanoparticles for flexible Electronics Packaging
    Applied Physics Letters, 2010
    Co-Authors: A. Hu, Hani Alarifi, Giuseppe Compagnini, Giuseppe Patanè, J Y Guo, Yan Zhou, C.x. Xu
    Abstract:

    We achieve robust bonding of Cu wires to Cu pads on polyimide with silver nanopaste cured at 373 K. The paste is prepared by simply condensing Ag nanoparticle (NP) solution via centrifuging. The bonding is formed by solid state sintering of Ag NPs through neck growth and direct metallic bonding between clean Ag–Cu interfaces. Both experiment and Monte Carlo simulation confirm that the melting point of joint clusters increases during sintering. This creates improved bonds for use at an elevated operating temperature using Ag NPs.

Johan Liu - One of the best experts on this subject based on the ideXlab platform.

  • new nano thermal interface material for heat removal in Electronics Packaging
    2006 1st Electronic Systemintegration Technology Conference, 2006
    Co-Authors: Johan Liu, M O Olorunyomi, Wen Xuan Wang, T Aronsson, Dongkai Shangguan
    Abstract:

    The need for faster, smaller, and more reliable and efficient products has resulted in increase of heat generated in microelectronic components. The removal of the heat generated is an important issue in electronic Packaging. The present research work aims at developing a new class of nano-Thermal Interface Material (NanoTIM) that has low thermal resistance, high thermal conductivity and mechanical strength using the electrospinning process. With the electrospinning process, polymer nano-fibers with nano-scale diameter are formed. Nano-particles such as nano-silver particles, nano-carbon nanotubes (CNT) and nano-silicon carbide particles were embedded into the nano-fibers to enhance the thermal conductivity and to reduce the thermal resistivity. Optical and Scanning Electron Microscopy (SEM) analysis techniques were used to determine the morphology of the nano-composite fibers obtained. Thermal resistivity, conductivity and mechanical strength of the nano-composite materials formed were measured. In addition, the manufactured nano-materials were characterized using the Thermo Gravimetric Analyzer (TGA) and the Differential Scanning Calorimetric (DSC) analysis techniques to study the softening, melting as well as degradation behavior. The mechanical strength was also studied using a multi-functional mechanical tester. The results show that the nano-fiber based composite nano-TIMs have similar thermal conductivity, 3 to 9 times lower thermal resistivity, similar operation temperature range and degradation behavior, 2 to 5 times higher ultimate tensile strength, in comparison with commercially available TIMs. By adding adhesive functions into the process, a new class of nano-TIM tape has been produced.

  • aca bonding technology for low cost Electronics Packaging applications current status and remaining challenges
    4th International Conference on Adhesive Joining and Coating Technology in Electronics Manufacturing. Proceedings. Presented at Adhesives in Electroni, 2000
    Co-Authors: Johan Liu
    Abstract:

    Anisotropically Conductive Adhesives (ACAs) have been used in Electronics Packaging for decades on glass substrate, and recently in contactless smart-card module assembly and for bare chip attach on flexible and rigid substrates. This paper summarises various technologies used in connection with ACA joining. A summary of our understanding on electrical, thermal, physical, chemical, environmental and cost behaviours of ACAs in conjunction with various Packaging applications are elaborated. Finally, future research areas and remaining issues are pointed out.

  • experimental and theoretical characterization of electrical contact in anisotropically conductive adhesive
    IEEE Transactions on Advanced Packaging, 2000
    Co-Authors: Yanli Wang, Johan Liu, Xitao Wang, Zonghe Lai, Guoliang Chen, M Willander
    Abstract:

    Electrical conduction through anisotropically conductive adhesive (ACA) is caused by deformation of metal fillers under pressure and heat. In this work, the hardness of the electrical particles under various deformation degrees was determined by nano-indentor measurements and the electrical resistance of the electrical contacts was measured under various deformation degrees. Theoretical model and simulation have been developed for the microscopic mechanism of the electrical conduction through metal fillers in the anisotropically conductive adhesive. By comparing with experimental data it is concluded that the deformation of the metal filler in our ACA is plastic even at rather low external load. Further theoretical simulation reveals two important aspects of the conductance characteristics. The conductance is improved by increasing the external load but the dependence of the conductance on the spatial position of the metal filler becomes stronger. Design and optimization of the ACA with respect to the absolute value of the electric conductance and its dependence on the spatial position of the metal filler are of essential importance for the Electronics Packaging application of the anisotropically conductive adhesives.

  • ACA bonding technology for low cost Electronics Packaging applications-current status and remaining challenges
    4th International Conference on Adhesive Joining and Coating Technology in Electronics Manufacturing, Proceedings - Presented at Adhesives in Electron, 2000
    Co-Authors: Johan Liu
    Abstract:

    Anisotropically Conductive Adhesives (ACAs) have been used in Electronics Packaging for over a decade on glass substrates, and more recently in contactless smart-card module assembly and for bare chip attach on flexible and rigid substrates. Summarises various technologies used in connection with ACA joining. A summary of our understanding of the electrical, thermal, physical, chemical, environmental and cost behaviours of ACAs in conjunction with various Packaging applications Is elaborated. Finally, future research areas and remaining issues are pointed out.

  • Overview of conductive adhesive joining technology in Electronics Packaging applications
    Proceedings of 3rd International Conference on Adhesive Joining and Coating Technology in Electronics Manufacturing 1998 (Cat. No.98EX180), 2026
    Co-Authors: Johan Liu, Z. Lai, Helge Kristiansen, C. Khoo
    Abstract:

    This paper presents an overview of the current status of use of conductive adhesives in various Electronics Packaging applications. Strong emphasis is placed on recent developments in surface mount and flip-chip technology, as these methods in combination with conductive adhesives represent the latest developments in the area of Electronics Packaging. It is concluded that little practical use of conductive adhesives in surface mount has been found. In flip-chip applications, both isotropically and anisotropically conductive adhesives (ICAs and ACAs) have been used in real applications. Greater use is expected in the near future in this fast developing area.

Thierry Lebey - One of the best experts on this subject based on the ideXlab platform.

  • co fired aln tin assembly as a new substrate technology for high temperature power Electronics Packaging
    Ceramics International, 2013
    Co-Authors: Zarel Valdeznava, Masahiro Kozako, Sophie Guillemetfritsch, Marc Ferrato, Thierry Lebey
    Abstract:

    New wide-band gap semiconductors (SC) for power Electronics such as SiC, GaN and diamond will allow higher power densities, leading to higher operating temperatures. However, the surrounding materials will also undergo an increase in temperature, meaning that a parallel effort is needed in SC Packaging technologies research. One of the essential components, the substrate, is used to insulate electrically the SC from the rest of the system, drain the generated heat and provide a path to connect the SC to the rest of the system. Direct bonded copper (DBC) and active metal-brazed (AMB) substrates have limited temperature and cycling operation, owing to the large differences in the thermal expansion coefficients between the ceramics and the metals. In this work we propose a new and original substrate technology based on two co-sintered ceramics: an insulating ceramic (AlN) and a conductive one (TIN). The microstructure, the chemical compatibility and the electrical properties indicate that the proposed substrate could operate at a temperature above 200 1C the current substrate technologies, which makes it particularly attractive for high-temperature power Electronics applications.

  • stress grading in integrated power modules
    Conference on Electrical Insulation and Dielectric Phenomena, 2007
    Co-Authors: Cyrille Duchesne, Thierry Lebey, Emmanuel Dutarde, M M Guyennet, Selim Dagdag
    Abstract:

    Power Electronics Packaging, like integrated power modules, constitute an advanced technology leading to power density increase, weight and volume decrease and enhancing the reliability level. However, the continuous increase of the voltage lead to questions regarding power device environment. We discuss in the following different solutions able to achieve the electric stress gradation.

Yunhui Mei - One of the best experts on this subject based on the ideXlab platform.

  • rapid sintering of nano ag paste at low current to bond large area 100 mm2 power chips for Electronics Packaging
    Journal of Materials Processing Technology, 2018
    Co-Authors: Yijing Xie, Yunhui Mei, Yanjie Wang, Haining Xie, Kun Zhang, Shuangtao Feng, Kim Shyong Siow
    Abstract:

    Abstract We achieved robust bonding of a large area power chip (>100 mm2) with sintered Ag joint produced by the electrical current assisted sintering (ECAS) technique operating at low current (1.1 kA) and short sintering time (10 s). Our ECAS-ed Ag joint possessed low thermal resistance (∼0.18 °C/W), high density (89.6%), as well as good static and dynamic electrical properties during switching on and off of the power chip. Our TEM analysis explained that the good electrical and thermal performances of the power chip were attributed to the high density of twins formed in the ECAS-ed nano-Ag joint.

  • simplification of low temperature sintering nanosilver for power Electronics Packaging
    Journal of Electronic Materials, 2013
    Co-Authors: Yunhui Mei, Yunjiao Cao, Dan Han
    Abstract:

    Conventional solders cannot meet the requirements for high-temperature applications. Recently, a low-temperature sintering technique involving a nanosilver paste has been developed for attaching semiconductor chips to substrates. Sintered nanosilver joints showed high reliability in high-temperature applications. We used the nanosilver paste to attach 10 mm × 10 mm chips by introducing a pressure as low as only 1 MPa during drying at 185°C. Die-shear tests showed that shear strengths of higher than 50 MPa could be generated by applying 5 MPa at 225°C for only 10 s or 1 MPa at 150°C for 600 s, followed by sintering for only 60 s at 275°C. The sintering temperature could be reduced to 250°C in most applications with a slight reduction in shear strength. As a result of good bonding, significant plastic flow and ductile fracture of the sheared silver joint could be observed by scanning electron microscopy (SEM). SEM also showed that the fracture of the sheared silver joint was a cohesive failure.

  • rapid sintering nanosilver joint by pulse current for power Electronics Packaging
    IEEE Transactions on Device and Materials Reliability, 2013
    Co-Authors: Yunhui Mei, Yunjiao Cao
    Abstract:

    Sintering of nanosilver paste has been extensively studied as a lead-free die-attach solution for bonding semiconductor chips. The bonding process typically consists of a low-temperature drying step to remove organic solvents in the paste followed by sintering at around 250°C . Normally, a soak time of several minutes at the sintering temperature is necessary to establish strong bond strength by the conventional heating method. In this paper, we tested the feasibility of applying pulses of alternating electrical current through the nanosilver bonding layer to achieve strong joints in less than a second, not minutes. Experiments were carried out by joining rectangular copper blocks that were either coated with a layer of electroplated silver or without. A layer of nanosilver paste was stencil printed on one block, dried at temperature below 100°C, before the other copper block was placed on. The bonding members were then inserted under an alternating-current spot-welding machine for rapid joining with current pulses. Die-shear test was used to quantify the joint strength. Investigated processing variables on the joint strength were current level, current-on time, nanosilver bondline thickness, predrying temperature and time, and copper surface finish. Scanning electron microscopy was used to characterize the joint microstructure. It is suggestive that the current sintering of nanosilver paste could be used for rapid joining of metal-to-metal connection, such as bonding copper bus bars onto power Electronics modules.

C.x. Xu - One of the best experts on this subject based on the ideXlab platform.

  • Low temperature sintering of Ag nanoparticles for flexible Electronics Packaging
    Applied Physics Letters, 2010
    Co-Authors: A. Hu, Hani Alarifi, Giuseppe Compagnini, Giuseppe Patanè, J Y Guo, Yan Zhou, C.x. Xu
    Abstract:

    We achieve robust bonding of Cu wires to Cu pads on polyimide with silver nanopaste cured at 373 K. The paste is prepared by simply condensing Ag nanoparticle (NP) solution via centrifuging. The bonding is formed by solid state sintering of Ag NPs through neck growth and direct metallic bonding between clean Ag–Cu interfaces. Both experiment and Monte Carlo simulation confirm that the melting point of joint clusters increases during sintering. This creates improved bonds for use at an elevated operating temperature using Ag NPs.