Ōsaka, Japan
Ōsaka, Japan

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Okada A.,Daiken Chemical Co. | Okada A.,University of Fukui | Ogihara T.,University of Fukui
Key Engineering Materials | Year: 2010

Several types of Ag powder were used as electrode paste for a multilayer ceramic substrate. The shrinkage behavior of the silver powders was investigated during the sintering. Bending and cracking were frequently observed on the substrate when coarse powders that show a broad size distribution and aggregation were used. The shrinkage curve of the Ag paste obtained by spray pyrolysis agreed well with that of the substrate. Furthermore, the electrical properties of the Ag paste were also determined. The resistivity of a silver electrode sintered at 900°C was about 2.00×10-6 Ω·cm. © (2010) Trans Tech Publications.


Yamamoto Y.,Daiken Chemical Co. | Yamamoto Y.,University of Fukui | Ogihara T.,University of Fukui
Key Engineering Materials | Year: 2010

Silver nanoparticles produced with a solid-phase thermal decomposition method were used for the preparation of a conductive paste supporting curing at low temperatures. The conducting paste was prepared by blending fine spherical silver powder and silver nanoparticles with a diameter of 20nm in order to reduce the electric resistivity of the electrodes. Although the viscosity of the conducting paste increased by about 25% after 60 days, it exhibited superior stability to dispersion in comparison to commercial paste. The electric resistivity of the electrode was of the order of 10 -6Ωcm at a curing temperature of 200° C. Using this conducting paste, it is possible to print at widths of 20μ m. The resistivity was further reduced by 1% in the high temperature test at 120° C, by 5% in the high humidity and high temperature test, and by 5% during the thermal shock test at temperatures ranging from -45 to 80° C. © (2010) Trans Tech Publications.


Uruno H.,Toyohashi University of Technology | Oke S.,Tsuyama National College of Technology | Suda Y.,Toyohashi University of Technology | Takikawa H.,Toyohashi University of Technology | And 5 more authors.
IEEJ Transactions on Fundamentals and Materials | Year: 2010

RuO2 nanoparticles were supported on arc-black (AB) with different pH of Ru colloidal solutions. For lower pH, RuO2 particles in nanometer size were dispersed on AB, although for higher pH, RuO2 particles were aggregated. The RuO2-supported-AB prepared at pH 5 had the highest amount of RuO2 and showed the highest capacitance. © 2010 The Institute of Electrical Engineers of Japan.


Sato T.,Toyohashi University of Technology | Suda Y.,Toyohashi University of Technology | Uruno H.,Toyohashi University of Technology | Takikawa H.,Toyohashi University of Technology | And 5 more authors.
Journal of Physics: Conference Series | Year: 2012

In this study, we used two types of carbon nanomaterials, arc-black (AcB) which has an amorphous structure and carbon nano-balloon (CNB) which has a graphitic structure as electrochemical capacitor electrodes. We made a coin electrode from these carbon materials and fabricated an electric double-layer capacitor (EDLC) that sandwiches a separator between the coin electrodes. On the other hand, RuO 2 was loaded on these carbon materials, and we fabricated a pseudo-capacitor that has an ion insertion mechanism into RuO 2. For comparison with these carbon materials, activated carbon (AC) was also used for a capacitor electrode. The electrochemical properties of all the capacitors were evaluated in 1M H 2SO 4 aqueous solution. As a result of EDLC performance, AcB electrode had a higher specific capacitance than AC electrode at a high scan rate (≥ 100 mV/s). In the evaluation of pseudo-capacitor performance, RuO 2-loaded CNB electrode showed a high specific capacitance of 734 F/g per RuO 2 weight. © Published under licence by IOP Publishing Ltd.


Ikeda T.,Toyohashi University of Technology | Kaida S.,Toyohashi University of Technology | Satou T.,Toyohashi University of Technology | Suda Y.,Toyohashi University of Technology | And 7 more authors.
Japanese Journal of Applied Physics | Year: 2011

Arc black (AcB) was prepared in N2 gas using the twin-torch arc discharge apparatus, and a hollow capsule with graphite layers named a carbon nano balloon (CNB) was obtained by heat treatment of the AcB in Ar gas at 2400 °C. Transmission electron microscopy, Raman spectroscopy, thermogravimetric analysis, and compressive resistivity measurement confirmed that the CNB was well graphitized. In the direct methanol fuel cell (DMFC) application of these carbon nanomaterials, catalyst metal nanoparticles were supported on the AcB, and a membrane-electrode assembly (MEA) was formed from the catalyst-supported AcB and the CNB by hotpressing them on an electrolyte film. The MEA containing the CNB resulted in a higher DMFC performance than that without the CNB, indicating that the CNB with lower compressive resistivity than the AcB works as a material for the improvement of electric conductivity in an MEA. © 2011 The Japan Society of Applied Physics.


Shigemune T.,Osaka University | Koizumi A.,Osaka University | Kashiwagi Y.,Osaka Municipal Technical Research Institute | Kakiuchi H.,Daiken Chemical Co. | And 12 more authors.
Zairyo/Journal of the Society of Materials Science, Japan | Year: 2015

We fabricated Ag electrodes on GaN-based blue light-emitting diodes (LEDs) by direct screen printing with Ag nanoparticle paste instead of commonly used dry processes. After the direct screen printing of Ag nanoparticle pastes on p-type GaN, successive sintering was carried out at 450°C for 30 min. LEDs with a square electrode size of 0.5 mm showed a threshold and operating voltage of 3.3 and 4.4 V, respectively. The maximum emission efficiency was obtained at 13 mA. These results suggest that screen printed Ag electrodes have a potential for use in GaN-based blue LEDs. © 2015 The Society of Materials Science, Japan.


Morisada Y.,Osaka Municipal Technical Research Institute | Nagaoka T.,Osaka Municipal Technical Research Institute | Fukusumi M.,Osaka Municipal Technical Research Institute | Kashiwagi Y.,Osaka Municipal Technical Research Institute | And 4 more authors.
Journal of Electronic Materials | Year: 2011

A low-temperature pressureless bonding process using a mixture of trimodal-sized Ag nanoparticles was proposed to form excellent Cu-to-Cu joints. Cu-to-Cu joints formed using the mixed Ag nanoparticles at 350°C for 5 min showed bonding strength of 13.7 MPa, in spite of the bonding process without pressure. Elongated dimples observed on the fracture surface of the Cu-to-Cu joint strongly support the effect of the trimodal mixture system of Ag nanoparticles in the low-temperature pressureless bonding process. © 2011 TMS.


Obata S.,Gifu Prefectural Ceramics Research Institute | Iwata Y.,Gifu Prefectural Ceramics Research Institute | Yokoyama H.,Gifu Prefectural Ceramics Research Institute | Sakurada O.,Gifu University | And 2 more authors.
Ceramic Transactions | Year: 2010

A water soluble titanate compound (TNB Lac) prepared by direct reaction of titanium tetra n butoxide (TNB) with lactic acid (Lac) in water showed characteristics of a polyanion and acted as a dispersant for preparing aqueous aluminum titanate (Al 2TiO 5) slurries. The isoelectric point of Al 2TiO 3 particles shifted to lower pH with increasing concentration of TNB Lac. The rheological behavior of aqueous Al 2TiO 5 slurries with TNB Lac was examined and evaluated. The dispersion and fluidity of aqueous Al 2TiO 5 slurry were enhanced by the addition of TNB Lac at pH 10, and the thickening limit of the well dispersed and fluidized slurry with 0.075 mmol g 1 TNB Lac was found at a solid content of 79 wt%. A high green density of 63% for the sintered powder was obtained through the slip casting process using slurries with 0.075 mmol g 1 TNB Lac. The maximum relative density value of the sintered bodies was 96.5% when the green body was fired at 1500°C. The sintered body had a homogeneous grain growth and dense microstructure without pores or abnormal grain growth.


Kashiwagi Y.,Osaka Municipal Technical Research Institute | Saitoh M.,Osaka Municipal Technical Research Institute | Hasegawa T.,Osaka Municipal Technical Research Institute | Matsukawa K.,Osaka Municipal Technical Research Institute | And 8 more authors.
2016 International Conference on Electronics Packaging, ICEP 2016 | Year: 2016

Ag electrodes were formed on InGaN/GaN multi-quantum well blue light emitting diode (LED) substrates by using needle-type dispensing of Ag nanoink and the heat treatment as wet processes. The patterns by using the needle-type dispenser system are drawn out of a dot matrix method like an inkjet printer, and thus, arbitrary graphics can be produced. After patterning, the conductive Ag films as electrodes were formed by sintering at 450°C for 30 minutes under the atmospheric conditions. The fabricated LED emitted blue light with a threshold and operating voltage of 3.3 and 4.4 V, respectively. These results suggest that the wet processed Ag electrodes have a potential for use in the production of GaN based LEDs. © 2016 The Japan Institute of Electronics Packaging.

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