• Proceedings of the Materials Research Society of Korea Conference
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• 2009.05a
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• pp.12.2-12.2
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• 2009

전자 디스플레이 산업의 중요성과 미래사회에서 요구되는 정보기기로써 유연한 기판을 사용한 소자에 대한 수요가 급격히 증가하고 있으며, 이들 산업에 응용되기 위해서는 저비용, 고생산 공정이 요구되고 있다. 이를 위해 인쇄전자 기술에 대한 연구가 활발히 진행되고 있다. 특히, 금속배선은 모든 소자의 기본이면서 낮은 저항과 높은 신뢰성을 동시에 요구하고 있어 인쇄전자 기술이 해결해야 할 가장 어려운 난제 중의 하나이다. 따라서 본 연구에서는 낮은 저항과 높은 신뢰성을 만족시킬 수 있는 새로운 금속배선 공정으로서 폴리이미드 필름을 초발수 처리한 후 친수 패턴을 하여 전도성 잉크에 함침함으로서 친수 패턴을 따라 금속배선이 이루어 지도록 하는 방법을 제안하고자 한다. 폴리이미드 필름의 표면을 플라즈마 처리하여 표면에 나노돌기를 형성시키고 불소기를 함유한 코팅층을 형성시킴으로써 물에 대한 접촉각이 $150^{\circ}$이상이 되도록 초발수 처리할 수 있었다. 초발수 처리된 폴리이미드 기판에 쉐도우 마스크를 사용하여 UV조사함으로써 조사된 부분만 친수성을 가지는 패턴을 형성하였다. 이렇게 친수 패턴이 제작된 초발수 폴리이미드 유연기판을 실버잉크에 함침함으로써 선폭 $200{\mu}m$를 가지는 금속배선을 형성시켰다. 형성된 금속배선의 단면 형상을 측정하였으며, 열처리를 통하여 비저항이 $30{\mu}{\Omega}$-cm를 얻을 수 있었다. 통상 1회의 함침으로는 금속배선의 두께가 150nm정도로 금속배선으로 사용하기에는 얇아 배선의 두께를 증가시키기 위하여 수 회 함침을 시도하여 $2{\mu}m$의 두께로 증가시킬 수 있었다. 이때 선폭과 선간 간격은 크게 변하지 않고 두께만 증가시킬 수 있었다. 이는 금속배선을 형성한 후에도 폴리이미드 유연기판의 초발수성은 그대로 유지되어 여러번 함침할 때 잉크가 이미 형성된 배선에만 묻게 되어 두께는 증가하나 선폭과 선간 간격은 증가하지 않는 것으로 판단된다. 사용한 실버잉크는 실버의 함량은 10~20wt%인 수계 잉크였다.

• Korean Journal of Materials Research
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• v.30 no.11
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• pp.621-626
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• 2020

This study is aimed at preparing and evaluating the plasma resistance of YAS (Y₂O₃-Al₂O₃-SiO₂) coating layer with crystalline YAG phase contents. For this purpose, YAS frits with controlled phase contents are prepared and melt-coated on sintered Al₂O₃ ceramics. Then, the results of phase analysis of crystalline YAS coating layer are compared to that of YAS frits, and discussed with regard to the plasma resistance of the YAS coating layer. The phase contents of the YAS frit change in a manner different from that of the prepared YAS coating layer, presumably owing to the composition change of YAS frit during the melt-coating process. The plasma resistance of the YAS coating layer is shown to increase with the YAG phase contents in the coating layer. Comparing the weight loss of YAS coating layer with those of commercial Y₂O₃, Al₂O₃, and quartz ceramics, the plasma resistance of the prepared YAS coating layer is 8 times higher than that of quartz and 3 times higher than that of Al₂O₃; this layer shows 70 % of the resistance of Y₂O₃.

• Proceedings of the Korean Vacuum Society Conference
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• 1999.07a
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• pp.212-212
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• 1999

Ar-O2 분위기의 Plasma 표면 처리된 OPP 의 polymer 위에 약 400$\AA$ 정도로 sputter 코팅된 Al의 부착력에 관하여 연구를 하였다. 금속과 polymer와 같이 성질이 서로 다른 물질이 서로 결합할 때 접착력은 제품의 성능과 신뢰도를 결정하는데 매우 중요한 인자이다. 최근 고분자재료의 표면을 플라즈마 처리 (plasma surface treatment)에 의해 고분자와 금속도포(coating) 층간의 접착력향상에 따라, 증착필름 및 인쇄용 필름 등의 기능도 향상시킬 수 있다. 저온 plasma를 이용한 표면처리는 plastic 재료가 가지고 있는 기본적인 특성을 저해하지 않고, 그 표면 층만을 개량하는 plasma 또는 sputter etching 갚은 electrical discharge 방법은 진공 증착 방식에서 많이 사용되고 있다. 7$\mu\textrm{m}$의 두께 OPP polymer를 10m/min의 속도로 OPP의 표면을 연속 plasma pretreatment를 하였다. 5$\times$10-2torr에서, PEM(Plasma Emission Monitor)를 이용하여 plasma intensity에 따른 Ar/O2비를 변화시키면서 test를 하였다. AFM과 XPS를 이용하여 OPP의 표면분석을 하였다. 이 plasma처리는 기존의 D.C plasma 처리 방식과는 달리 Midium frequency AC voltage hollow cathod 방식으로 plasma를 발생된 high energy plasma 분위기를 만들 수 있다. 이러한 방식은 -cycle일 때 plasma로부터 발생된 전자가 polymer 표면을 bombard 하게 되고, +cycle 일 때 polymer 표면이 cathod 가 되어 active ion에 의해 sputtering 이 된다. 이때 plasma 처리기의 polymer 기판 후면에 magnet를 설치하여 높은 ionization을 발생시켜 처리 효과를 한층 높여 주었다. 이 plasma 처리는 표면 청정화, 표면 etching 이 동시에 행하는 것과 함께 장시간 처리에 의해 표면에서는 미세한 과, C=C기, -C-O-의 극성기의 도입에 의한 표면 개량이 된다는 것을 관찰할 수 있다. OPP polymer 표면을 Ar 100%로 plasma 처리한 경우 C-O, C=O 등의 carbonyl가 발생됨을 알 수 있었다. C-O, C=O 등의 carbynyl polor group이 도입됨에 따라 sputter된 Al의 접착력이 향상됨을 알 수 있으며, TEM 관찰 결과 grain size도 상당히 작아짐을 알 수 있었다.

• Korean Chemical Engineering Research
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• v.54 no.2
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• pp.262-267
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• 2016

In this study, we present an excellent approach for easily and uniformly immobilizing Pt, Au and bimetallic PtAu nanoparticles (NPs) on a multi-walled carbon nanotube (MWNT)-coated layer through dry plasma reduction. The NPs are stably and uniformly immobilized on the surface of MWNTs and the nanohybrid materials are applied to counter electrode (CE) of dye-sensitized solar cells (DSCs). The electrochemical properties of CEs are examined through cyclic voltammogram, electrochemical impedance spectroscopy, and Tafel measurements. As a result, both electrochemical catalytic activity and electrical conductivity are highest for PtAu/MWNT electrode. The DSC employing PtAu/MWNT CE exhibits power conversion efficiency of 7.9%. The efficiency is better than those of devices with MWNT (2.6%), AuNP/MWNT (2.7%) and PtNP/MWNT (7.5%) CEs.

• Journal of the Korean Electrochemical Society
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• v.16 no.3
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• pp.157-161
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• 2013

Porous $LiMn_{0.6}Fe_{0.4}PO_4$ (LMFP) was synthesized by a sol-gel process. Uniform dispersion of the conductive carbon source throughout LMFP with uniform carbon coating was achieved by heating a stoichiometric mixture of raw materials at $600^{\circ}C$ for 10 h. The crystal structure of LMFP was investigated by Rietveld refinement. The surface structure and pore properties were investigated by SEM, TEM and BET. The LMFP so obtained has a high specific surface area with a uniform, porous, and web-like nano-sized carbon layer at the surface. The initial discharge capacity and energy density were 152 mAh/g and 570 Wh/kg, respectively, at 0.1 C current density, and showed stable cycle performance. The combined effect of high porosity and uniform carbon coating leads to fast lithium ion diffusion and enhanced electrochemical performance.

• Journal of Ocean Engineering and Technology
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• v.11 no.3
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• pp.56-68
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• 1997

This work was intended to study the effect of a partial pressure ratio and a total pressure of reactive gases on the properties of TiC$_{x}$N$_{1-x}$ . coated layer. In this regard, various TiC$_{x}$N$_{1-x}$ coatings were synthesized with C2112 and N2 Mixture gas of different compositions by Arc Ion Plating process which has been highlighted for an industrial purpose. It was revealed from colors and X-ray diffraction patterns that the concentration of carbon of a TiC$_{x}$N$_{1-x}$ coating increases with a partial pressure ratio (PC$_{2}$H$_{2}$/PN$_{2}$) as well as a total pressure Of $C_{2}$H$_{2}$ and N$_{2}$ mixture gas. Accordingly, the hardness of TiC$_{x}$N$_{1-x}$ coated layer increased but the adhesion to the substrate of SKH 51 was degraded. On the other hand, the deposition rate was independent of a partial pressure ratio and a total pressure of mixture gas. It was found that a uniform gas distribution is critical for an industrial application since the composition of a coating depends strongly on the location of a substrate inside of the furnace. As a result of milling tests with different TiC$_{x}$N$_{1-x}$ coated end mills, the one which has a low carbon concentration was better than others studied in this work.d in this work.

• Journal of the Korean Ceramic Society
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• v.44 no.7
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• pp.368-374
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• 2007

CVD-SiC coating has been introduced as a protective layer in TRISO nuclear fuel particle of high temperature gas cooled reactor (HTGR) due to its excellent mechanical stability at high temperature. In order to prevent the failure of the TRISO particles, it is important to evaluate the fracture strength of the SiC coating layer. It is needed to develop a new simple characterization technique to evaluate the mechanical properties of the coating layer as a pre-irradiation step. In present work, direct strength measurement method with the specimen of hem i-spherical shell configuration was suggested. The indentation experiment on a hemisphere shell with a plate indenter was conducted. The fracture strength of the coating layer is related with the critical load for radial cracking of the shell. The finite element analysis was used to drive the semi-empirical equation for the strength measurement. The SiC hemispherical shells were successfully recovered from the section-grinding of TRISO coated particle and successive heat treatment in air. The strength of CVD-SiC coating layer was evaluated from the experimentally measured critical load during the indentation on SiC hemisphere shell. Weibull diagram of fracture strength was also constructed. This study suggested a new strength equation and experimental method to measure the fracture strength of CVD-SiC coating of TRISO coated fuel particles.

• Journal of the Korean Ceramic Society
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• v.45 no.4
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• pp.245-249
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• 2008

The SiC and ZrC are critical and essential materials in TRISO coated fuel particles since they act as protective layers against diffusion of metallic and gaseous fission products and provides mechanical strength for the fuel particle. However, SiC and ZrC have critical disadvantage that SiC loses chemical integrity by thermal dissociation at high temperature and mechanical properties of ZrC are weaker than SiC. In order to complement these problems, we made new combinations of the coating layers that the ZrC layers composed of SiC. In this study, after Silicon carbide(SiC) were chemically vapor deposited on graphite substrate, Zirconium carbide(ZrC) were deposited on SiC/graphite substrate by using Zr reaction technology with Zr sponge materials. The different morphologies of sub-deposited SiC layers were correlated with microstructure, chemical composition and mechanical properties of deposited ZrC films. Relationships between deposition pressure and microstructure of deposited ZrC films were discussed. The deposited ZrC films on SiC of faceted structure with smaller grain size has better mechanical properties than deposited ZrC on another structure due to surface growth trend and microstructure of sub-deposited layer.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.33 no.3
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• pp.219-224
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• 2020

Al₂O₃ powders with particle sizes of 0.35 ㎛, 0.5 ㎛, 1.5 ㎛, and 2.5 ㎛ are deposited onto glass and Cu substrates using the aerosol deposition (AD) process. The deposition characteristics of Al₂O₃ films using those four types of Al₂O₃ powders are investigated to determine the influence of the particle size on the films. To observe detailed micro-structures of the films, the cross-section and surface morphology are observed. Then, the crystalline size and internal strain are calculated from X-ray diffraction peaks in order to confirm the hammering effect as well as the micro-strain during the AD deposition. From the above results, deposition mechanisms related to the particle size are studied. The results of this study indicate the optimal particle size and formation mechanisms for dense Al₂O₃ film with a smooth surface roughness as well as for a porous Al₂O₃ film with a rough surface roughness.

• Journal of Sensor Science and Technology
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• v.6 no.5
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• pp.356-361
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• 1997

Fiber-optic evanescent wave sensor was designed and fabricated to detect mouse immunoglobulin G(IgG) with decladed optical fiber on which anti-mouse IgG was immobilized. A sensitivity obtained by any direct or competitive method was lower than $1\;{\mu}g/m{\ell}$. Anti-mouse IgG was immobilized on 93.9% of core surface of optical fiber by simple adsorption method. The effect of postcoating using bovine serum albumin to remove non-specific binding was not observed. As the ratio of fluorescein to mouse IgG increased, the fluorescence signal increased, but that increase showed no linear relationship. Our fiber-optic sensor system could be used as immunosensor by measuring evanescent fluorescence in antigen-antibody reaction with good sensitivity below $1{\mu}g/m{\ell}$ level.