• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2005년도 추계학술대회 논문집
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• pp.423-426
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• 2005

A new chip on glass(COG) technique by making use of a high power diode laser for LCD driver IC packaging of LCD has been developed. A laser joining technology of the connection of IC chip to glass panel has several advantages over conventional method such as hot plate joining: shorter process time, high reliability of joining, and better fur fine pitch joining. The reach time to cure temperature of ACF in laser joining is within 1 second. In this study, results show that the total process time of joining is reduced by halves than that of conventional method. The adhesion strength is mainly 100-250 N/cm. It is confirmed that the COG technology using high power diode laser joining can be applied to advanced LCDs with a fine pitch.

• Journal of the Korean Wood Science and Technology
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• 제49권3호
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• pp.274-282
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• 2021

Transparent and colorless melamine-urea-formaldehyde (MUF) resins make it difficult to identify the area of wood failure percentage (WFP) in the fracture surface of bonded wood specimens. Therefore, in this study, we develop a method of measuring WFP after the adhesion strength measurement of MUF resins under shear stress. The fractured wood surface of b lock shear strength (BSS) specimens bonded with cold-setting MUF resins at three melamine contents (20%, 30%, and 40%) was marked black, and then, WFP was accurately measured via image analysis. WFP values measured using this method consistently increased with BSS as the melamine content increased, showing the reliability of this new method. The results suggested that this new method is useful and reliable for measuring the WFP of the fracture surface of wood specimens bonded with colorless adhesives such as urea-formaldehyde, MUF, and melamine-formaldehyde resins.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2010년도 하계학술대회 논문집
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• pp.150-150
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• 2010

Carbon nanotubes have drawn attention as one of the most promising emitter materials ever known not only due to their nanometer-scale radius of curvature at tip and extremely high aspect ratios but also due to their strong mechanical strength, excellent thermal conductivity, good chemical stability, etc. Some applications of CNTs as emitters, such as X-ray tubes and microwave amplifiers, require high current emission over a small emitter area. The field emission for high current density often damages CNT emitters by Joule heating, field evaporation, or electrostatic interaction. In order to endure the high current density emission, CNT emitters should be optimally fabricated in terms of material properties and morphological aspects: highly crystalline CNT materials, low gas emission during electron emission in vacuum, optimal emitter distribution density, optimal aspect ratio of emitters, uniform emitter height, strong emitter adhesion onto a substrate, etc. We attempted a novel approach to fabricate CNT emitters to meet some of requirements described above, including highly crystalline CNT materials, low gas emission, and strong emitter adhesion. In this study, CNT emitters were fabricated by filtrating an aqueous suspension of highly crystalline thin multiwalled CNTs (Hanwha Nanotech Inc.) through a metal mesh. The metal mesh served as a support and fixture frame of CNT emitters. When 5 ml of the CNT suspension was engaged in filtration through a 400 mesh, the CNT layers were formed to be as thick as the mesh at the mesh openings. The CNT emitter sample of $1{\times}1\;cm^2$ in size was characteristic of the turn-on electrical field of 2.7 V/${\mu}m$ and the current density of 14.5 mA at 5.8 V/${\mu}m$ without noticeable deterioration of emitters. This study seems to provide a novel fabrication route to simply produce small-size CNT emitters for high current emission with reliability.

• 한국재료학회지
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• 제16권4호
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• pp.257-263
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• 2006

We have investigated the effect of silver added to Cu films on the microstructure evolution, resistivity, surface morphology, stress relaxation temperature, and adhesion properties of Cu(Ag) alloy thin films deposited on Mo glue layer upon annealing. In addition, pure Cu films deposited on Mo has been annealed and compared. The results show that the silver in Cu(Ag) thin films control the grain growth through the coarsening of its precipitates upon annealing at $300^{\circ}C{\sim}600^{\circ}C$ and the grain growth of Cu reveals the activation energy of 0.22 eV, approximately one third of activation energy for diffusion of Ag dopant along the grain boundaries in Cu matrix (0.75 eV). This indicates that the grain growth can be controlled by Ag diffusion along the grain boundaries. In addition, the grain growth can be a major contributor to the decreased resistivity of Cu(Ag) alloy thin films at the temperature of $300^{\circ}C{\sim}500^{\circ}C$, and decreases the resistivity of Cu(Ag) thin films to $1.96{\mu}{\Omega}-cm$ after annealing at $600^{\circ}C$. Furthermore, the addition of Ag increases the stress relaxation temperature of Cu(Ag) thin films, and thus leading to the enhanced resistance to the void formation, which starts at $300^{\circ}C$ in the pure Cu thin films. Moreover, Cu(Ag) thin films shows the increased adhesion properties, possibly resulting from the Ag segregating to the interface. Consequently, the Cu(Ag) thin films can be used as a metallization of advanced TFT-LCDs.

• 대한금속재료학회지
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• 제48권12호
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• pp.1116-1122
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• 2010

Metal interconnections of multilayer Al/Ni and TiW/seed-Ni/Ni were formed on glass, and the adhesion strength and nanoindentation response of the composite layers were evaluated. The Al/Ni multilayer was formed by an anodic bonding of glass to Al and subsequent electroless plating of Ni, while the TiW/Ni multilayer was fabricated by sputter deposition of TiW and seed-Ni onto glass and electroless plating of Ni. Because of the diffusion of aluminum into glass during the anodic bonding, anodically bonded glass/Al joint exhibited greater interfacial strength than the sputtered glass/TiW one. The Al/Ni on glass also showed excellent resistance against delamination by bending deformation compared to the TiW/seed-Ni/Ni on glass. From the nanoindentation experiment of each metal layer on glass, it was found that the aluminum layer had extremely low hardness and elastic modulus similar to the glass substrate and played a beneficial role in the delamination resistance by lessening stress intensification at the joint. The indentation data of the multilayers also supported superior joint reliability of the Al/Ni to glass compared to that of the TiW/seed-Ni/Ni to glass.

• Current Photovoltaic Research
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• 제7권3호
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• pp.65-70
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• 2019

As a demand of higher power photovoltaic modules, shingled, multi-busbar, half-cell, and bifacial techniques are developed. Multi-busbar module has advantage for large amount of light havesting. And, half-cell is high power module for reducing resistive losses and higher shade tolerance. Recently, researches on multi-busbar is focused on reliability according to adhesion and intermetallic compound between Sn-Pb solder and Ag electrode. And half-cell module is researched to comparing with full-sized cell module for structure difference. In this study, we investigated the factors affecting to efficiency and adhesion of multi-wires half-cell module according to wire thickness, solder thickness, and flux. The results of solar simulator and peel test was that peel strength and efficiency of soldered cell is not related. But samples with flux including high solid material showed high efficiency. The results of FE-SEM and EDX line scan on cross-section between wire and Ag electrode for different flux showed thickness of solder joint between wire and Ag electrode is increasing through solid material increasing. Flux including high solid material would affect to solder behavior on Ag electrode. Higher solid material occurred lower growth of IMC layer because solder permeate to sider of wire ribbon than Ag electrode. And it increased fill factor for high efficiency. In soldering process, amount of solid material in flux and solder thickness are the factor related with characteristic of soldered photovoltaic cell.

• 접착 및 계면
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• 제24권2호
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• pp.60-63
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• 2023

AlGaN/GaN 이종접합 구조는 이차원 전자 가스층(2-DEG)으로 인해 높은 전자이동도를 갖고 있으며, 넓은 밴드갭을 갖기 때문에 고온에서 높은 항복전압을 갖는 특성을 가지고 있어, 고전력, 고주파 전자 소자로 주목받고 있다. 이러한 이점을 갖고 있음에도 불구하고, 전류 붕괴 등의 다양한 소자 신뢰성에 영향을 주는 인자들이 있기 때문에 이를 해결하고자, 본 논문에서는 금속-유기-화학기상증착법을 이용하여 AlGaN/GaN 이종 접합구조와 SiN 패시베이션 층을 연속 증착시켰다. 이를 통해 HEMTs소자에 SiN패시베이션이 미치는 재료 특성 및 전기적 특성을 분석했으며, 결과를 바탕으로 저주파 잡음 특성을 측정해 소자의 전도 메커니즘 모델과 채널 내의 결함의 원인에 대해서 분석하였다.

• 마이크로전자및패키징학회지
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• 제14권4호
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• pp.43-48
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• 2007

LTCC 기판제작에 있어서 Post 전극형성은 실제 IC 및 수동부품을 탑재하는 Pad 형성 부분으로 전극 표면의 특성에 큰 영향을 미치게 된다. 본 연구에서는 일반적인 전기로를 이용한 post 전극 소성시 발생되는 문제점들 개선하여 마이크로파 소결을 통한 전극 미세 구조의 치밀화 및 이에 따른 신뢰성 기초 평가를 진행하였다. 일반적인 전기로와 마이크로파 소결 조건에 따른 전극과 LTCC 세라믹 상태를 평가하였다. 또한 과소성 및 탈바인더 공정시 Out gas 불충분에 의한 전극 부풀림 현상을 개선할 수 있는 효과를 얻을 수 있었으며 실제 solder ball 형성후 실장형 전극의 고착강도를 측정한 결과 기존 전기로에 비해서 30% 고착강도가 증가 하였다. 또한 소결시간을 기존 전기로 10시간에 비해 30분 정도에서 소결 공정이 이루어지므로 95%정도 시간을 단축시킬 수 있음을 확인하였다. 이는 소성로 설계를 통한 양산성, 효율성에 크게 증대되리라 예상된다.

• 접착 및 계면
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• 제10권4호
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• pp.191-198
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• 2009

지방족 에폭시 수지인 glycerol diglycidyl ether (GDE)에 단관능성 아크릴 수지인 2-carboxyethyl acrylate (2-CEA) 또는 2-hydroxyethyl acrylate (2-HEA)를 반응시켜 지방족 에폭시 아크릴레이트를 제조하였다. FT-IR, $^1H$-NMR, 그리고 $^{13}C$-NMR를 사용하여 생성물을 확인하였고, 수율은 prep-LC를 사용하여 얻었다. 생성물의 자외선 경화거동은 photo-DSC를 사용하였고, 열경화 반응성은 DSC를 사용하여 얻었다. 2-CEA의 반응성이 2-HEA보다 월등히 높음을 알 수 있었고, 2-CEA로부터 제조한 지방족 에폭시 아크릴레이트(GEA-C)의 수율은 약 83%이었다. 촉매를 제거한 GEA-C 생성물의 자외선 경화반응($T_{max}$)은 약 10 s로 빠르게 진행되었다. GEA-C는 투명하고, 내열성이 우수하며 저점도를 갖고 있음을 확인할 수 있었다. ${\Delta}E^*$는 2.51, 점도는 192 cps, 5% 중량감소 때의 온도는 $299^{\circ}C$이었다. Kissinger와 Ozawa-Flynn-Wall 식으로 얻은 GEA-C의 열경화 반응의 활성화에너지($E_a$)는 91~92 kJ/mol이었다.

• 마이크로전자및패키징학회지
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• 제29권3호
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• pp.37-42
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• 2022

최근 반도체 패키지 구조는 점점 더 얇아지고 복잡해지고 있다. 두께가 얇아짐에 이종 계면에서 물성차이에 의한 박리는 심화될 수 있으며 따라서 계면의 신뢰성이 패키징 설계에 중요한 요소라 할 수 있다. 특히, 반도체 패키징에 많이 사용되는 폴리머는 온도와 수분에 영향을 크게 받기 때문에 환경에 따른 물성 변화 고려가 필수적이다. 따라서, 본 연구에서는 다양한 온도조건에서 수분의 흡습과 탈습을 모두 고려한 패키지 구조의 계면 박리 예측을 유한 요소 해석을 통해 수행하였다. 확산계수와 포화 수분 함량과 같은 재료의 물성은 흡습 실험을 통해 확보하였으며, 흡습 이후 TMA 와 TGA 를 통하여 각 재료의 수분 팽창 계수를 확보하였다. 각 계면의 접합 강도 평가를 위해 수분의 영향을 고려하여 다양한 온도 조건에서 마이크로 전단 실험을 수행하였다. 이러한 물성을 바탕으로 온도와 수분에 의해 발생하는 변형을 모두 고려한 패키지 박리 예측 해석을 수행하였으며, 결과적으로 리플로우 공정 동안의 실시간 수분 탈습 거동을 고려한 계면 박리 예측을 성공적으로 수행하였다.