• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2008.06a
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• pp.346-346
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• 2008

최근 디지털 컨버젼스에 의해서 정보 단말기 network가 디지털 기술을 기반으로 유기적으로 융 복합화 되고 있으며 BT, NT, ET, IT의 융합 기술의 필요성이 점차적으로 증대되고 있다. 이러한 환경 하에서 다양한 정보 및 서비스의 송신 및 수신이 가능한 휴대 단말기의 필요성에 부응하여 기존의 전화 기능, 카메라, DMB 이외에도 홈 네트워크, mobile internet 등 더욱 다양한 기능들이 요구되고 있다. 종래에는 수동 부품과 능동 부품의 실장을 별개로 추진했으나 최근에는 수동 및 능동 부품을 하나의 패키지 내에 실장 가능하도록 하는 3-D Integration을 추진하고 있다. 지금까지 여러 부품들을 실장 시키기 위한 공정들의 대부분은 높은 온도에서 공정이 이루어졌으나 여러 부품들을 손상 없이 집적화하고 실장하기 위해서는 저온화 공정이 필요하다. 최근 많은 저온 공정 중에서 Aerosol Deposition Method는 상온에서 세라믹 후막을 성막할 수 있어 가장 주목받고 있는 공정중의 하나이다. 본 연구에서는 3-D Integration을 실현하기 위해 이종 접합에 유리하고 상온에서 성막 공정이 이루어지는 Aerosol Deposition Method를 이용하여 금속 기판 위에 금속, 폴리머, 세라믹 후막을 성막시켰다. 기판 재료로는 Cu 기판을 사용하였으며 출발 파우더로는 Polyimide 파우더와 $Al_2O_3$ 파우더, Ag 파우더를 사용하였으며 이종 접합간의 메커니즘의 양상을 보기 위해 같은 조건에서 이종 접합간의 성막률을 비교하였으며 FE-SEM으로 미세 구조를 관찰하였다. 또한 기판의 표면 거칠기에 따른 메커니즘의 양상을 연구하였다.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1999.05a
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• pp.329-332
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• 1999

In this paper, BST((Bao.&o,dTi0:3) thin films were deposited by the rf magnetron sputtering method on Pt/$SiO_2$/Si substrate. Pt, $RuO_2$, Ag, Cu films for the formation of top electrode were deposited on BST thm films. And then Top Electrodes/BST/Pt capacitors were annealed with rapid thermal annealing(RTA) at various temperature. We have investigated effect of post-annealing on the electrical properties such as dielectric constant and leakage current of the capacitors. It was found that electrical properties of the capacitors were greatly depended on the annealing temperatures as well as the materials of top electrodes. In BST thin films with Pt top electrode was annealed at $700^{\circ}C$. the dielectric constant was measured to the value of 346 at l[kHzl and the leakage current was obtained to the value of $8.76\times10^8$[A/$\textrm{cm}^2$] at the forward bias of 2[V].

• Journal of the Korean Society of Safety
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• v.27 no.6
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• pp.7-13
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• 2012

A lack of study on the dynamic tensile strengths of Sn-based solder joints at high strain rates was the motivation for the present study. A modified miniature Charpy impact testing machine instrumented with an impact sensor was built to quantitatively evaluate the dynamic impact strength of a solder joint under tensile impact loading. This study evaluated the tensile strength of lead-free solder ball joints at strain rates from $1.8{\times}10^3s^{-1}$ and $8.5{\times}10^3s^{-1}$. The maximum tensile strength of the solder ball joint decreases as the load speed increases in the testing range. This tensile strength represented that of the interface because of the interfacial fracture site. The tensile strengths of solder joints between Sn-3.0Ag-0.5Cu and copper substrate were between 21.7 MPa and 8.6 MPa in the high strain range.

• Journal of the Korean institute of surface engineering
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• v.48 no.1
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• pp.11-22
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• 2015

Pd alloy hydrogen membranes for hydrogen purification and separation need thermal stability at high temperature for commercial applications. Intermetallic diffusion between the Pd alloy film and the porous metal support gives rise to serious problems in long-term stability of Pd alloy membranes. Ceramic barriers are widely used to prevent the intermetallic diffusion from the porous metal support. However, these layers result in poor adhesion at the interface between film and barrier because of the fundamentally poor chemical affinity and a large thermal stress. In this study, we developed Pd alloy membranes having a dense microstructure and saturated composition on modified metal supports by advanced DC magnetron sputtering and heat treatment for enhanced thermal stability. Experimental results showed that Pd-Cu and Pd-Ag alloy membranes had considerably enhanced long-term stability owing to stable, dense alloy film microstructure and saturated composition, effective diffusion barrier, and good adhesive interface layer.

• Proceedings of the KIEE Conference
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• 2003.07c
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• pp.1840-1842
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• 2003

This paper describes an experiment of detecting a temperature and components of arc plasma of electrical circuit breaker with a spectroscopic system. The system includes an optical fiber, a monochromator which has three gratings from low to high resolution and ICCD of which time resolution is 50 ns. This system enables measuring a temperature and components of arc plasma of a circuit breaker which is generated and extinguished in a few ms. We use a Planck's law and Boltzmann Plot method for calculating a temperature of arc plasma. A Xenon lamp is used for calibrating the system and this is very important for calculating a temperature of arc plasma. In this study, Arc plasma of Ag and Cu contact was investigated and these represent the contact of low voltage and extra-ultra high voltage circuit breaker, respectively. 8 $kA_{rms}$ test current was applied with a capacitor bank.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.13 no.3
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• pp.254-258
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• 2000

Current leads of high $T_{c}$ superconductor were fabricated with Bi excess B $i_{2.2}$/S $r_{1.8}$/C $a_{1}$/C $u_{2}$/ $O_{x}$ composition by rapid cooling method. The dimensions of final samples were fixed 3 mm and 8 mm diameter with 50 mm length each To control uniform density the samples were preformed by CIP(Cold Isostatic Press) process and followed by partial or full melting process after raising up to 90$0^{\circ}C$ for 30min. Plate shaped microstructure was clearly observed adjacent to the Ag tube wall and the size of plate was about 100$\mu$m. However the severe destruction of growth orientation was shown in the inner growth part. critical temperature ( $T_{c}$) was about 53~71K after directional growth while Tc was decreased about 77~80 K before directional growth. After directional growth critical current( $I_{c}$) and critical current density( $J_{c}$) in the specimen of 8 mm diameter at 50 K were about 110 A and 280 A/c $m^2$ respectively.pectively.ely.

• Proceedings of the Korean Society of Dyers and Finishers Conference
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• 2011.11a
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• pp.34-34
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• 2011

Recently, people have concerned about environmental pollution. This environmental pollution occur due to many reasons such as heavy metal ions and anions. In this regard, many researchers have studied organic materials to monitor above reasons to protect environmental pollution. One of the organic materials for this function is chemosensor. This chemosensor has been studied and reported about monitoring toxic heavy metal ions and anions. In this study, the dye sensor was designed and synthesized through reaction of Rhodamine 6G and 1,3-Indanedion. this dye sensor selective detected $Hg^{2+}$ metal ions while showing red color absorption and yellowish-green strong fluorescence emission compared to other heavy metal ions such as $Cu^{2+}$, $Hg^{2+}$, $Ag^{2+}$, $Zn^{2+}$, $Fe^{2+}$ and $Fe^{3+}$. In this regard, we anticipated that this dye senosr can provide an significant material for monitoring mercury which cause environmental pollution. Thus, We investigated detailed properties of this dye sesnor with using UV-Vis absorption and fluorescent spectrophotometer, Job's plot method for metal binding complex, computational simulated calculation named Material Studio 4.3 suite to approach for electron distribution and HOMO/LUMO.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2005.07a
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• pp.262-263
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• 2005

For mechanical and electrical stability and environment protection, Cu and stainless steel stabilizer is laminated to Ag layer to produce a composite neutral-axis(N-A) architecture in which the YBCO layer is centered between the oxide buffered metallic substrate and stabilizer strip lamination. this architecture allows the wire to meet operational requirements including stresses at cryogenic temperature, winding tensions, mechanical bending requirements thermal and electrical stability under fault conditions. we have experimentally studied mechanical properties of laminated stainless steel stabilizer on YBCO coated conductors. we have laminated YBCO coated conductors by continuous dipping soldering process. we have investigated lamination interface between solder and stabilizer, YBCO coated conductor. we evaluated bonding properties tensile / shear bonding strength, peeling strength laminated YBCO coated conductors.

• Proceedings of the Korean Vacuum Society Conference
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• 2010.02a
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• pp.339-339
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• 2010

The metallic nanoparticles (Pt, Au, Ag. Cu, etc.) supported on ceria-titania mixed oxide exhibit a high catalytic activity for the water gas shift reaction ($H_2O\;+\;CO\;{\leftrightarrow}\;H_2\;+\;CO_2$) and the CO oxidation ($O_2\;+\;2CO\;{\leftrightarrow}\;2CO_2$). It has been speculated that the high catalytic activity is related to the easy exchange of the oxidation states of ceria ($Ce^{3+}$ and $Ce^{4+}$) on titania, but very little is known about the ceria titanium interaction, the growth mode of metal on ceria titania complex, and the reaction mechanism. In this work, the growth of $CeO_x$ and Au/$CeO_x$ on rutile $TiO_2$(110) have been investigated by Scanning Tunneling Microscopy (STM), Photoelectron Spectroscopy (PES), and DFT calculation. In the $CeO_x/TiO_2$(110) systems, the titania substrate imposes on the ceria nanoparticles non-typical coordination modes, favoring a $Ce^{3+}$ oxidation state and enhancing their chemical activity. The deposition of metal on a $CeO_x/TiO_2$(110) substrate generates much smaller nanoparticles with an extremely high activity. We proposed a mechanism that there is a strong coupling of the chemical properties of the admetal and the mixed-metal oxide: The adsorption and dissociation of water probably take place on the oxide, CO adsorbs on the admetal nanoparticles, and all subsequent reaction steps occur at the oxide-admetal interface.

• Korean Journal of Materials Research
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• v.19 no.6
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• pp.337-343
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• 2009

In this study, we optimized Pb-free Sn/Ni plating thickness and conditions were optimized to counteract the environmental regulations, such as RoHS and ELV(End-of Life Vehicles). The $B_{10}$ life verification method was also suggested to have been successful when used with the accelerated life test(ALT) for assessing Pb-free solder joint life of piezoelectric (PZT) ceramic resonator. In order to evaluate the solder joint life, a modified Norris-Landzberg equation and a Coffin-Manson equation were utilized. Test vehicles that were composed of 2520 PZT ceramic resonator on FR-4 PCB with Sn-3.0Ag-0.5Cu for ALT were manufactured as well. Thermal shock test was conducted with 1,500 cycles from $(-40{\pm}2)^{\circ}C$ to $(120{\pm}2)^{\circ}C$, and 30 minutes dwell time at each temperature, respectively. It was discovered that the thermal shock test is a very useful method in introducing the CTE mismatch caused by thermo-mechanical stress at the solder joints. The resonance frequency of test components was measured and observed the microsection views were also observed to confirm the crack generation of the solder joints.