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Kyung-wook Paik - One of the best experts on this subject based on the ideXlab platform.
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A Study on the Anchoring Polymer Layer (APL) Anisotropic Conductive Films (ACFs) with Self-Exposed Conductive Particles Surface for Ultra-Fine Pitch Chip-on-Glass (COG) Applications
2019 IEEE 69th Electronic Components and Technology Conference (ECTC), 2019Co-Authors: Dal-ji Yoo, Kyung-wook PaikAbstract:In this study, APL ACFs combined with self-exposed Conductive Particles surface are newly introduced. The effects of APL ACFs properties on Conductive Particle movement and interconnection stability for ultra-fine pitch COG applications were reported earlier. It was found that the APL structure will not only suppress the Conductive Particles movement during ACFs bonding process, but also prevent electrical short circuit formation between neighboring bumps for ultra-fine pitch applications. Since the APL material has high tensile strength, the capture rate of APL ACFs is about 3 times higher than that of conventional ACFs. However, to achieve a stable electrical interconnection, the APL ACFs require additional process steps such as an oxygen plasma etching process to remove the APL polymer skins coated on the top and bottom surfaces of Conductive Particles. In this study, the polymer skin can be removed during the APL fabrication process using the self-activate monolayer (SAM) treatment on Conductive Particles. As a result, stable ACFs joint formation can be achieved without any additional oxygen plasma etching process for APL fabrication processes.
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A Study on the Conductive Particle Movements in Polyvinylidene Fluoride Anchoring Polymer Layer Anisotropic Conductive Films for 20- $\mu$ m Fine-Pitch Interconnection
IEEE Transactions on Components Packaging and Manufacturing Technology, 2019Co-Authors: Sanghoon Lee, Dal-jin Yoon, Kyung-wook PaikAbstract:Fine-pitch interconnection technology in electronic packaging has become very important because of electrical interconnection issues such as high contact resistance and open-/short-circuit failure. Nanofiber anisotropic Conductive films (ACFs) and nanofiber sheet ACFs (NS ACFs) have been developed and reported by our research group to address the challenges for fine-pitch interconnection problems. However, they require complicated fabrication processes such as electrospinning, thermal compression, and plasma etching. In this paper, anchoring polymer layer (APL) ACFs and their fabrication process are introduced. The goal in employing the APL ACFs was to simplify the complex fabrication steps of nanofibers and NS ACFs by coating methods without compromising electrical performance. With the APL coating method, the electrospinning, thermal compression, and plasma etching steps can be reduced to a single process. Nonetheless, APL ACFs exhibit excellent electrical conduction at 20- $\mu \text{m}$ fine-pitch interconnections by successfully suppressing the movement of Conductive Particles in the ACF. The capture rate of the APL ACFs was 78%, which was comparable to the value 81% of NS ACFs. APL ACFs open the possibility of cost-effective production of ACFs interconnection materials for fine-pitch applications. Therefore, we use the word “anchoring” to suppress the movement of Conductive Particles during resin flow. In this paper, we discuss the fabrication process of APL structure and electrical properties of APL ACFs.
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A Study on the Anchoring Polymer Layer(APL) Solder Anisotropic Conductive Films (ACFs) for Ultra Fine Pitch Flex-on-Flex (FOF) Assembly Using an Ultrasonic Bonding Method
2018 IEEE 68th Electronic Components and Technology Conference (ECTC), 2018Co-Authors: Dal-ji Yoo, Sang Hoo Lee, Kyung-wook PaikAbstract:In this study, APL solder ACFs combined with an ultrasonic bonding process are newly introduced. The effects of APL ACFs properties on Conductive Particle movement and interconnection stability of ultra-fine pitch COG applications were reported earlier. It was found that the APL structure will not only suppress the Conductive Particles movement during ACFs bonding process for ultra-fine pitch applications, but also prevent electrical short circuit formation between neighboring bumps. However, to achieve a stable electrical interconnection, the APL ACFs require additional process steps such as an oxygen plasma etch process to remove the APL polymer skins surrounding the Conductive Particles using a thermo-compression bonding method. However, during the vertical ultrasonic bonding process, it was found that the APL polymer skins of the Conductive Particles were successfully removed by a vertical ultrasonic vibration. Therefore, stable solder joint formation can be achieved without any additional plasma etching process needed for non-solder Conductive Particles.
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Effects of the Nylon Anchoring Polymer Layer on the Conductive Particle Movements of Anisotropic Conductive Films for Ultrafine Pitch Chip-on-Glass Applications
IEEE Transactions on Components Packaging and Manufacturing Technology, 2018Co-Authors: Dal-jin Yoon, Sanghoon Lee, Kyung-wook PaikAbstract:Electronic packaging technology has become very important in electronic devices, because electrical interconnection problems such as high contact resistance and short-circuit failure have become serious issues in ultrafine pitch interconnection. In this paper, a nylon anchoring polymer layer (APL) structure has been introduced into the anisotropic Conductive films (ACFs) system. Then, the effects of nylon APL properties on Conductive Particle movement of ACFs and its interconnection stability for ultrafine pitch chip-on-glass (COG) applications were investigated. The APL structure can significantly suppress the Particles’ movement for ultrafine pitch COG applications, and prevent the short-circuit problem between neighboring electrodes. After ACFs bonding process, the Conductive Particles capture rate of the conventional ACFs was 33%; however, that of the nylon APL ACFs showed 90%. In addition, the nylon APL ACFs showed excellent electrical interconnection properties such as stable contact resistances without any open or short-circuit failures. As a result, the nylon APL ACFs can be used as new interconnection materials for ultrafine pitch interconnection applications.
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Effects of Polymer Conductive Particle Contents on the Electrical Performance and Reliability of 50- $\mu \text{m}$ Pitch Flex-on-Flex Assemblies Using Anisotropic Conductive Films
IEEE Transactions on Components Packaging and Manufacturing Technology, 2017Co-Authors: Yan Pan, Lu Song, Shuye Zhang, Xionghui Cai, Kyung-wook PaikAbstract:Anisotropic Conductive films (ACFs) composed of an adhesive polymer resin and fine Conductive Particles such as metal-coated polymer Conductive Particles are interconnect materials for fine-pitch flex-on-flex (FOF) assembly technologies due to their fine-pitch handling capability, low-temperature bonding, and stable electrical properties due to the compliance of polymer Conductive Particles. For the ultrafine pitch FOF assembly, the polymer Conductive Particle content becomes more important due to electrical storage problem between electrodes. To design better quality ACFs materials for 50- $\mu \text{m}$ FOF assemblies, the effects of polymer Conductive Particle contents on the electrical stability and reliability of FOF ACFs joints were investigated. It was found that the bonding temperature should be less than the deformation temperature of polymer Conductive Particles, and proper Conductive Particles content should be applied to obtain the stable joint contact resistance and ACF joint morphology. When the Conductive Particle contents increased more than 4wt%, the gap width between the top and bottom electrodes increased and the deformation of Conductive Particles became less, resulting in higher contact resistance. Therefore, 4wt% of Conductive Particle ACFs bonded at 175 °C, 2 MPa for 10 s showed the lowest contact resistance of 36.2 $\text{m}\Omega $ and excellent thermal cycle (T/C) reliability up to 1000 cycles. As a result, the optimum polymer Conductive Particles contents and the bonding conditions such as temperature, pressure, and times were achieved to obtain the best performance and T/C reliability of 50- $\mu \text{m}$ pitch FOF assembly using ACFs.
Niculina Musat - One of the best experts on this subject based on the ideXlab platform.
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Conductive Particles enable syntrophic acetate oxidation between geobacter and methanosarcina from coastal sediments
Mbio, 2018Co-Authors: Amelia-elena Rotaru, Hryhoriy Stryhanyuk, Federica Calabrese, Hannah Sophia Weber, Oona Snoeyenboswest, Hans-hermann Richnow, Per O.j. Hall, Florin Musat, Pravin Malla Shrestha, Niculina MusatAbstract:: Coastal sediments are rich in Conductive Particles, possibly affecting microbial processes for which acetate is a central intermediate. In the methanogenic zone, acetate is consumed by methanogens and/or syntrophic acetate-oxidizing (SAO) consortia. SAO consortia live under extreme thermodynamic pressure, and their survival depends on successful partnership. Here, we demonstrate that Conductive Particles enable the partnership between SAO bacteria (i.e., Geobacter spp.) and methanogens (Methanosarcina spp.) from the coastal sediments of the Bothnian Bay of the Baltic Sea. Baltic methanogenic sediments were rich in Conductive minerals, had an apparent isotopic fractionation characteristic of CO2-reductive methanogenesis, and were inhabited by Geobacter and Methanosarcina As long as Conductive Particles were delivered, Geobacter and Methanosarcina persisted, whereas exclusion of Conductive Particles led to the extinction of Geobacter Baltic Geobacter did not establish a direct electric contact with Methanosarcina, necessitating Conductive Particles as electrical conduits. Within SAO consortia, Geobacter was an efficient [13C]acetate utilizer, accounting for 82% of the assimilation and 27% of the breakdown of acetate. Geobacter benefits from the association with the methanogen, because in the absence of an electron acceptor it can use Methanosarcina as a terminal electron sink. Consequently, inhibition of methanogenesis constrained the SAO activity of Geobacter as well. A potential benefit for Methanosarcina partnering with Geobacter is that together they competitively exclude acetoclastic methanogens like Methanothrix from an environment rich in Conductive Particles. Conductive Particle-mediated SAO could explain the abundance of acetate oxidizers like Geobacter in the methanogenic zone of sediments where no electron acceptors other than CO2 are available.IMPORTANCE Acetate-oxidizing bacteria are known to thrive in mutualistic consortia in which H2 or formate is shuttled to a methane-producing Archaea partner. Here, we discovered that such bacteria could instead transfer electrons via Conductive minerals. Mineral SAO (syntrophic acetate oxidation) could be a vital pathway for CO2-reductive methanogenesis in the environment, especially in sediments rich in Conductive minerals. Mineral-facilitated SAO is therefore of potential importance for both iron and methane cycles in sediments and soils. Additionally, our observations imply that agricultural runoff or amendments with Conductive chars could trigger a significant increase in methane emissions.
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Conductive Particles enable syntrophic acetate oxidation between geobacter and methanosarcina from coastal sediments
bioRxiv, 2017Co-Authors: Amelia-elena Rotaru, Hryhoriy Stryhanyuk, Federica Calabrese, Hannah Sophia Weber, Oona Snoeyenboswest, Hans-hermann Richnow, Per O.j. Hall, Florin Musat, Pravin Malla Shrestha, Niculina MusatAbstract:Coastal sediments are rich in Conductive minerals, which could impact microbial processes for which acetate is a central intermediate. In the methanogenic zone, acetate is consumed by methanogens and/or syntrophic acetate-oxidizing (SAO) consortia. SAO consortia live under extreme thermodynamic pressure and their survival depends on successful partnership. Here we demonstrate that Conductive minerals facilitate a SAO partnership between Geobacter and Methanosarcina from the coastal sediments of the Bothnian Bay, Baltic Sea. Bothnian methanogenic sediments showed a high apparent isotopic fractionation (αc 1.07) characteristic of CO2-reductive methanogenesis. The native community was represented by electrogens such as Geobacter and methanogens like Methanosarcina. Upon the addition of Conductive Particles (activated carbon and magnetite), methanogenesis from acetate increased fourfold. Geobacter (96% related to G. psychrophilus) and Methanosarcina (99% related to M. subterranea) dominated the Conductive Particle-spiked SAO communities. Using NanoSIMS we demonstrated that during SAO, Geobacter incorporated 82% of the labeled acetate as compared to only 18% by Methanosarcina. At the same time, Geobacter converted 27% of the 13C-acetate to 13CO2 as detected by IRMS. Indigenous soluble shuttles were not involved in SAO, since spiking fresh cultures with spent-media filtrate had no effect on methanogenic rates. Our results demonstrate that Geobacter oxidizes acetate to CO2 while transferring electrons extracellularly via Conductive Particles to Methanosarcina, which utilizes them for CO2 reduction to methane. In natural environments, mediation of SAO by Conductive Particles between electrogens and methanogens could impact the iron and methane cycles.
Ndy N. Ekere - One of the best experts on this subject based on the ideXlab platform.
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effect of Particle size ratio on the conducting percolation threshold of granular Conductive insulating composites
Journal of Physics D, 2004Co-Authors: Da He, Ndy N. EkereAbstract:In this paper, we apply Monte Carlo simulation to investigate the Conductive percolation threshold of granular composite of Conductive and insulating powders with amorphous structure. We focus on the effect of insulating to Conductive Particle size ratio λ = di/dc on the conducting percolation threshold pc (the volume fraction of the Conductive powder). Simulation results show that, for λ = 1, the percolation threshold pc lies between simple cubic and body centred cubic site percolation thresholds, and that as λ increases the percolation threshold decreases. We also use the structural information obtained by the simulation to study the nonlinear current–voltage characteristics of composite with solid volume fraction of Conductive powder below pc in terms of electron tunnelling for nanoscale powders, dielectric breakdown for microscale or larger powders, and pressing induced conduction for non-rigid insulating powders.
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Effect of Particle size ratio on the conducting percolation threshold of granular Conductive–insulating composites
Journal of Physics D, 2004Co-Authors: Da He, Ndy N. EkereAbstract:In this paper, we apply Monte Carlo simulation to investigate the Conductive percolation threshold of granular composite of Conductive and insulating powders with amorphous structure. We focus on the effect of insulating to Conductive Particle size ratio λ = di/dc on the conducting percolation threshold pc (the volume fraction of the Conductive powder). Simulation results show that, for λ = 1, the percolation threshold pc lies between simple cubic and body centred cubic site percolation thresholds, and that as λ increases the percolation threshold decreases. We also use the structural information obtained by the simulation to study the nonlinear current–voltage characteristics of composite with solid volume fraction of Conductive powder below pc in terms of electron tunnelling for nanoscale powders, dielectric breakdown for microscale or larger powders, and pressing induced conduction for non-rigid insulating powders.
Amelia-elena Rotaru - One of the best experts on this subject based on the ideXlab platform.
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Conductive Particles enable syntrophic acetate oxidation between geobacter and methanosarcina from coastal sediments
Mbio, 2018Co-Authors: Amelia-elena Rotaru, Hryhoriy Stryhanyuk, Federica Calabrese, Hannah Sophia Weber, Oona Snoeyenboswest, Hans-hermann Richnow, Per O.j. Hall, Florin Musat, Pravin Malla Shrestha, Niculina MusatAbstract:: Coastal sediments are rich in Conductive Particles, possibly affecting microbial processes for which acetate is a central intermediate. In the methanogenic zone, acetate is consumed by methanogens and/or syntrophic acetate-oxidizing (SAO) consortia. SAO consortia live under extreme thermodynamic pressure, and their survival depends on successful partnership. Here, we demonstrate that Conductive Particles enable the partnership between SAO bacteria (i.e., Geobacter spp.) and methanogens (Methanosarcina spp.) from the coastal sediments of the Bothnian Bay of the Baltic Sea. Baltic methanogenic sediments were rich in Conductive minerals, had an apparent isotopic fractionation characteristic of CO2-reductive methanogenesis, and were inhabited by Geobacter and Methanosarcina As long as Conductive Particles were delivered, Geobacter and Methanosarcina persisted, whereas exclusion of Conductive Particles led to the extinction of Geobacter Baltic Geobacter did not establish a direct electric contact with Methanosarcina, necessitating Conductive Particles as electrical conduits. Within SAO consortia, Geobacter was an efficient [13C]acetate utilizer, accounting for 82% of the assimilation and 27% of the breakdown of acetate. Geobacter benefits from the association with the methanogen, because in the absence of an electron acceptor it can use Methanosarcina as a terminal electron sink. Consequently, inhibition of methanogenesis constrained the SAO activity of Geobacter as well. A potential benefit for Methanosarcina partnering with Geobacter is that together they competitively exclude acetoclastic methanogens like Methanothrix from an environment rich in Conductive Particles. Conductive Particle-mediated SAO could explain the abundance of acetate oxidizers like Geobacter in the methanogenic zone of sediments where no electron acceptors other than CO2 are available.IMPORTANCE Acetate-oxidizing bacteria are known to thrive in mutualistic consortia in which H2 or formate is shuttled to a methane-producing Archaea partner. Here, we discovered that such bacteria could instead transfer electrons via Conductive minerals. Mineral SAO (syntrophic acetate oxidation) could be a vital pathway for CO2-reductive methanogenesis in the environment, especially in sediments rich in Conductive minerals. Mineral-facilitated SAO is therefore of potential importance for both iron and methane cycles in sediments and soils. Additionally, our observations imply that agricultural runoff or amendments with Conductive chars could trigger a significant increase in methane emissions.
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Conductive Particles enable syntrophic acetate oxidation between geobacter and methanosarcina from coastal sediments
bioRxiv, 2017Co-Authors: Amelia-elena Rotaru, Hryhoriy Stryhanyuk, Federica Calabrese, Hannah Sophia Weber, Oona Snoeyenboswest, Hans-hermann Richnow, Per O.j. Hall, Florin Musat, Pravin Malla Shrestha, Niculina MusatAbstract:Coastal sediments are rich in Conductive minerals, which could impact microbial processes for which acetate is a central intermediate. In the methanogenic zone, acetate is consumed by methanogens and/or syntrophic acetate-oxidizing (SAO) consortia. SAO consortia live under extreme thermodynamic pressure and their survival depends on successful partnership. Here we demonstrate that Conductive minerals facilitate a SAO partnership between Geobacter and Methanosarcina from the coastal sediments of the Bothnian Bay, Baltic Sea. Bothnian methanogenic sediments showed a high apparent isotopic fractionation (αc 1.07) characteristic of CO2-reductive methanogenesis. The native community was represented by electrogens such as Geobacter and methanogens like Methanosarcina. Upon the addition of Conductive Particles (activated carbon and magnetite), methanogenesis from acetate increased fourfold. Geobacter (96% related to G. psychrophilus) and Methanosarcina (99% related to M. subterranea) dominated the Conductive Particle-spiked SAO communities. Using NanoSIMS we demonstrated that during SAO, Geobacter incorporated 82% of the labeled acetate as compared to only 18% by Methanosarcina. At the same time, Geobacter converted 27% of the 13C-acetate to 13CO2 as detected by IRMS. Indigenous soluble shuttles were not involved in SAO, since spiking fresh cultures with spent-media filtrate had no effect on methanogenic rates. Our results demonstrate that Geobacter oxidizes acetate to CO2 while transferring electrons extracellularly via Conductive Particles to Methanosarcina, which utilizes them for CO2 reduction to methane. In natural environments, mediation of SAO by Conductive Particles between electrogens and methanogens could impact the iron and methane cycles.
Da He - One of the best experts on this subject based on the ideXlab platform.
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effect of Particle size ratio on the conducting percolation threshold of granular Conductive insulating composites
Journal of Physics D, 2004Co-Authors: Da He, Ndy N. EkereAbstract:In this paper, we apply Monte Carlo simulation to investigate the Conductive percolation threshold of granular composite of Conductive and insulating powders with amorphous structure. We focus on the effect of insulating to Conductive Particle size ratio λ = di/dc on the conducting percolation threshold pc (the volume fraction of the Conductive powder). Simulation results show that, for λ = 1, the percolation threshold pc lies between simple cubic and body centred cubic site percolation thresholds, and that as λ increases the percolation threshold decreases. We also use the structural information obtained by the simulation to study the nonlinear current–voltage characteristics of composite with solid volume fraction of Conductive powder below pc in terms of electron tunnelling for nanoscale powders, dielectric breakdown for microscale or larger powders, and pressing induced conduction for non-rigid insulating powders.
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Effect of Particle size ratio on the conducting percolation threshold of granular Conductive–insulating composites
Journal of Physics D, 2004Co-Authors: Da He, Ndy N. EkereAbstract:In this paper, we apply Monte Carlo simulation to investigate the Conductive percolation threshold of granular composite of Conductive and insulating powders with amorphous structure. We focus on the effect of insulating to Conductive Particle size ratio λ = di/dc on the conducting percolation threshold pc (the volume fraction of the Conductive powder). Simulation results show that, for λ = 1, the percolation threshold pc lies between simple cubic and body centred cubic site percolation thresholds, and that as λ increases the percolation threshold decreases. We also use the structural information obtained by the simulation to study the nonlinear current–voltage characteristics of composite with solid volume fraction of Conductive powder below pc in terms of electron tunnelling for nanoscale powders, dielectric breakdown for microscale or larger powders, and pressing induced conduction for non-rigid insulating powders.