• Composites Research
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• 제36권6호
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• pp.422-428
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• 2023

스택 체결압에 의해 접촉되는 분리판(BP)과 탄소펠트전극(CFE) 사이의 전기적 접촉저항은 상대적으로 낮은 바나듐 레독스 흐름전지(VRFB) 스택의 체결압 때문에 스택 효율에 큰 여향을 미친다. 본 연구에서는 이러한 접촉저항을 줄이고 셀 성능을 향상시키기 위해 국부 가열 접합 공정을 통해 폴리에틸렌(PE) 복합재료-CFE 하이브리드 BP 구조를 개발하였다. 탄소섬유 복합재료 BP의 PE 매트릭스를 국부적으로 녹여 CFE의 탄소 섬유와 BP의 탄소 섬유의 직접 접촉 구조를 만들어 전기 접촉 저항을 감소시겼다. PE 복합재료-CFE 하이브리드 BP의 성능을 평가하기 위해 면적비저항(ASR)과 기체투과도를 측정하였다. 또한 스택 신뢰성을 측정하기 위해 내산성 시험을 수행하였다. 최종적으로, 개발된 PE 복합재료-CFE 하이브리드 BP와 기존의 BP의 성능을 비교 분석하기 위하여 VFRB 단위셀 충/방전 시험을 수행하였다.

• 한국분말야금학회:학술대회논문집
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• 한국분말야금학회 2006년도 Extended Abstracts of 2006 POWDER METALLURGY World Congress Part 1
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• pp.692-693
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• 2006

Behavior of stoichiometric and near-stoichiometric NiAl at plasma spray deposition, without and with a bond coat, for coating layers realization on a low alloyed steel substrate, has been investigated. In all variants, NiAl particle melting and subsequent welding at the impact with substrate were observed, forming a relatively compact and adherent coating layer with the NiAl stability maintaining - all assuring the coating layer oxidation and corrosion resistance. Good results from these points of view, also validated through corrosion tests, were obtained for 45:55 Ni:Al composition without a bond coat but adopting an Ar protective surrounding of plasma jet.

• 한국재료학회지
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• 제22권9호
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• pp.454-458
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• 2012

Various adhesive materials are used in flip chip packaging for electrical interconnection and structural reinforcement. In cases of COF(chip on film) packages, low temperature bonding adhesive is currently needed for the utilization of low thermal resistance substrate films, such as PEN(polyethylene naphthalate) and PET(polyethylene terephthalate). In this study, the effects of anhydride and dihydrazide hardeners on the low-temperature snap cure behavior of epoxy based non-conductive pastes(NCPs) were investigated to reduce flip chip bonding temperature. Dynamic DSC(differential scanning calorimetry) and isothermal DEA(dielectric analysis) results showed that the curing rate of MHHPA(hexahydro-4-methylphthalic anhydride) at $160^{\circ}C$ was faster than that of ADH(adipic dihydrazide) when considering the onset and peak curing temperatures. In a die shear test performed after flip chip bonding, however, ADH-containing formulations indicated faster trends in reaching saturated bond strength values due to the post curing effect. More enhanced HAST(highly accelerated stress test) reliability could be achieved in an assembly having a higher initial bond strength and, thus, MHHPA is considered to be a more effective hardener than ADH for low temperature snap cure NCPs.

• 한국안전학회지
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• 제27권2호
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• pp.7-12
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• 2012

This paper describes electrical fire on electric pad caused by defect of hot wires. We analyzed two type electric pad using by carbon type hot wire and magnetic shielded type hot wire. First, a carbon type hot wires electric pad is virtually impossible to connect hot wire as a method of electrical welding or soldering. In order to connect between hot wires, that has to splice carbon type material connector. If junction of hot wires was occurrence of poor connection on electric pad, it increase contact resistance on this junction point. With increasing contact resistance, junction of hot wires on electric pad generates local heating and finally leads to electrical fire. An electric pad using by a magnetic shielded type hot wire happened local heating on signal wire for sensing temperature-rise caused by applying current for magnetic shielded. With increasing local heating of signal wire, insulated coating of hot wire was melted. Finally the magnetic shielded type hot wire electric pad lead to electrical fire with breakdown between signal wire and hot wire. In this paper, we analyzed shape of damage in hot wire caused by electrical local heating and investigated fire cause on electric pad due to defect of hot wires.

• 마이크로전자및패키징학회지
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• 제25권2호
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• pp.9-17
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• 2018

Aluminum (Al) and its alloys have been used widely in a variety of industries such as structural, electronic, aerospace, and particularly automotive industries due to their lightweight characteristic, outstanding ductility, formability, high oxidation and corrosion resistance, and high thermal and electrical conductivity. Al have different kinds of alloys according to the various additional elements system and they should be selected properly depending on their effectiveness and suitability for their particular purpose. The major elements for Al alloys are silicon (Si), magnesium (Mg), manganese (Mn), copper (Cu), and zinc (Zn). In order for Al alloys to use for each industry, it is necessary to study of Al to Al joining and/or the Al to dissimilar materials joining to combine the individual parts into one. Many studies on joining technologies about Al to Al and Al to dissimilar materials have been performed such as press joining, bolted joint, welding, soldering, riveting, adhesive bonding, and brazing. This study reviews a variety of Al alloys and their joining method including its principles and properties with recent trends.

• Journal of Welding and Joining
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• 제33권5호
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• pp.1-8
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• 2015

Aluminium and its alloys are widely used in brazing various components in automotive industries due to their properties like lightweight, excellent ductility, malleability and formability, high oxidation and corrosion resistance, and high electrical and thermal conductivity. However, high machinability and strength of aluminium alloys are a serious concern during casting operations. The generation of porosity caused by dissolved gases and modifiers affects seriously the strength and quality of cast product. Brazing of Al and its alloys requires careful monitoring of temperature since theses alloys are brazed at around the melting temperature in most of the aluminium alloys. Therefore, the development of low temperature brazing filler alloys as well as superior strength Al alloys for various engineering applications is always in demand. In various heat exchangers and automotive applications, poor strength of Al alloys is due to the inherent porosities and casting defects. The unstable mechanical properties is therefore needed to be controlled by adding various additive elements in the aluminium and its alloys, by a change in the heat treatment procedure or by modifying the microstructure. In this regard, this article reports the effect of various elements added in aluminium alloys to improve microstructure, brazeability, machinability, castability as well as to stabilize the mechanical properties.

• Journal of Electrical Engineering and Technology
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• 제13권5호
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• pp.2059-2066
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• 2018

This study explored the feasibility of utilizing an SWCNT-coated fabric sensor for the development of a wearable motion sensing device. The extent of variation in electric resistance of the sensor material was evaluated by varying the fiber composition of the SWCNT-coated base fabrics, attachment methods, number of layers, and sensor width and length. 32 sensors were fabricated by employing different combinations of these variables. Using a custom-built experimental jig, the amount of voltage change in a fabric sensor as a function of the length was measured as the fabric sensors underwent loading-unloading test with induced strains of 30 %, 40 %, and 50 % at a frequency of 0.5 Hz. First-step analysis revealed the following: characteristics of the strain-voltage curves of the fabric sensors confirmed that 14 out of 32 sensors were evaluated as more suitable for measuring human joint movement, as they yield stable resistance values under tension-release conditions; furthermore, significantly stable resistance values were observed at each level of strain. Secondly, we analyzed the averaged maximum, minimum, and standard deviations at various strain levels. From this analysis, it was determined that the two-layer sensor structure and welding attachment method contributed to the improvement of sensing accuracy.

• 마이크로전자및패키징학회지
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• 제17권4호
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• pp.35-40
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• 2010

본 연구에서는 상용 고온 솔더 중 많이 쓰이고 있는 Sn-3.5Ag, Sn-0.7Cu, Sn-5.0Sb 솔더에 대한 열충격 시험, 열싸이클 시험, 고온 진동 복합 시험 신뢰성 평가를 하였다. 테스트 샘플을 제작하기 위해 Sn-3.5Ag, Sn-0.7Cu, Sn-5.0Sb 솔더볼을 ENIG 표면 처리된 BGA에 접합하였으며, 그 후 BGA샘플을 OSP 표면 처리된 PCB에 실장 하였다. 신뢰성평가 동안 저항변화를 측정하였으며 신뢰성 평가 전후 전단강도 시험을 통하여 접합강도의 변화를 평가하였다. Sn-3.5Ag의 솔더인 경우 전기저항과 접합강도의 저하가 비교 평가한 3가지 솔더 중 가장 높은 저하율을 보였으며 Sn-0.7Cu의 솔더가 신뢰성 평가 후에 비교적 높은 안정성을 나타내었다.

• 대한기계학회논문집A
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• 제38권8호
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• pp.893-898
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• 2014

펄스 레이저를 적용한 실버나노와이어의 접합 영향이 연구되었다. 조사된 레이저 펄스 에너지는 실버나노와이어 네트워크에서 실버나노와이어간에 접합을 유도하였으며 이로 인해 투명 기저위의 실버나노와이어 네트워크 박막에 전기 저항값을 조절할 수 있었다. 특히 이러한 나노네트워크에서의 접합은 개별 나노와이어의 접촉점의 형태로 발생되었고 접합의 효과는 전체 실버나노와이어 네트워크의 전기저항 변화 측정으로 평가하였다. 또한 레이저 빔 펄스폭 및 레이저 평균 출력이 나노와이어 접합 비율 평가에 적용되어 연구되었다. 실버나노와이어 네트워크의 광학 특성도 관찰되었으며 이에 레이저 공정 요소 대비 효과도 연구되었다. 최적화된 레이저빔 적용 재료처리는 특화된 국부 재료 특성 개선에 장점을 보였다. 펄스 레이저를 이용한 실버나노와이어의 재료처리의 적용과 그 효과에 대해서도 논의한다.

• 한국재료학회지
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• 제19권1호
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• pp.7-12
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• 2009

TFT-LCD is the most popular type of flat display panel in the information technology field. The back light unit is a main part of the structure of a TFT-LCD panel. Occasionally, studies have shown that failures of the CCFL of the BLU occur due to the poor weld characteristics of these materials. The aim of this study was to prepare some technical data and to characterize a microjoined electrode for the CCFL. Microstructure examinations, microhardness measurements, resistance measurements and microtensile tests of the microjoined electrode were carried out. The result indicates that a large amount of grain coarsening exists in the heat-affected zone (HAZ) of the weld between the cup and the pin. This grain coarsening of the HAZ between the cup and pin is caused by the welding cycle, which may have an influence on the lowest microhardness values. Fracturing of the microjoined electrode also occurred at the HAZ close to the cup between the weld holding the cup and the pin. Additionally, no specific changes of the electrical resistance among the cup, pin, and lead wire themselves or in the microjoined electrode were observed.