• 한국전기전자재료학회논문지
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• 제24권4호
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• pp.328-332
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• 2011

The formation of front metal contact silicon solar cells is required for low cost, low contact resistance to silicon surface. One of the front metal contacts is Ni/Cu plating that it is available to simply and inexpensive production to apply mass production. Ni is shown to be a suitable barrier to Cu diffusion into the silicon. The process of Ni electroless plating on front silicon surface is performed using a chemical bath. Additives and buffer agents such as ammonium chloride is added to maintain the stability and pH control of the bath. Ni deposition rate is found to vary with temperature, time, utilization of bath. The experimental result shown that Ni layer by SEM (scanning electron microscopy) and EDX analysis. Finally, plated Ni/Cu contact solar cell result in an efficiency of 17.69% on $2{\times}2\;cm^2$, Cz wafer.

• Tribology and Lubricants
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• 제12권4호
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• pp.52-59
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• 1996

The results of the electrical contact conductivity of multi-contact spots accounting the surface roughness and the non-conductive films of different origins such as air, water, cutting oil, and machining oil are presented. The array of metal spheres compressed between two flat plates has been used for simulation of the contact behavior of multiple contact of solids, under normal loading. Measurement of electrical contact resistance has been made using the equipment providing the adequate accuracy in the range of micro Ohms. The data on electrical contact resistance have been compared with theoretical predictions using the multiple contact model of constriction resistance. The effect of single spot number and array on conductivity of contact has been evaluated. The results of the experiments show that the contact resistance are closely related to the number of loading cycles, form of surface roughness, and presence of non-conductive films that reduce the size of the real electrical contact spots.

• 접착 및 계면
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• 제23권4호
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• pp.122-129
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• 2022

본 연구에서는 산소 플라즈마 처리시간을 실험 변수로 하여 금속섬유를 처리한 후 섬유표면에 산소함유 기능성 관능기를 도입하여 금속섬유의 친수성을 향상시키기 위한 연구로 플라즈마 처리 전, 후의 표면 특성 변화를 scanning electron microscope (SEM)과 x-ray photoelectron spectroscopy (XPS)를 사용하여 관찰하였다. 또한 플라즈마 처리시간이 금속섬유의 표면에 미치는 영향을 관찰하기 위해 극성 용매와 비극성 용매에 대한 금속섬유의 접촉각 변화를 측정하였다. 측정된 접촉각을 이용해 표면 자유에너지 변화를 계산한 후 산소 플라즈마 처리 전, 후의 금속섬유에 대한 접촉각과 표면 자유에너지를 비교하였으며 접착일과의 상관관계도 고찰하였다. 이런 금속섬유의 표면 변화가 다른 소재와의 복합 시 계면에서의 전단강도 향상에 미치는 영향을 알아보기 위해 microdroplet 시편을 제조하여 계면 전단강도를 측정하였으며 접착일과의 상관관계도 함께 파악하였다. 따라서, 금속섬유의 산소플라즈마 처리는 섬유표면에 물리적인 표면적 증가로 인한 수지와의 접촉면의 증가와 표면의 산소함유 기능성 관능기의 도입에 따른 접촉각, 표면 에너지의 변화에 따른 표면 친수화로 고분자 수지와의 계면 전단강도를 향상시켜주는 결과를 얻었다.

• 대한기계학회논문집A
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• 제35권6호
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• pp.643-649
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• 2011

LNG 선박에 사용되는 초저온용 버터플라이 밸브의 개발에 있어, 누설검증은 가장 중요한 설계공정 중 하나이다. 초저온에서 누설방지가 가능한 실로서 인코넬 스프링과 같은 탄성지지체가 포함된 O-링 형태의 메탈실이 널리 사용되고 있으나, 제작비가 고가인 단점을 갖고 있다. 이에 대한 대안으로 부가적인 탄성지지체 없이도 누설조건을 만족시키며, 제작비가 저렴한 탄성 메탈실의 개발이 요구되고 있다. 본 연구에서는 탄성 메탈실의 누설방지를 위한 설계조건을 정립하여, 초저온 및 고압환경에서 누설방지가 가능한 탄성 메탈실의 형상을 수치해석을 통해 고찰하였다. 아울러 이를 기반으로 시제품을 개발하고, 상온 및 초저온 상태에서 BS6755 및 BS6364 에 준하는 누설시험을 실시하여 누설여부를 확인하였다.

• 한국재료학회:학술대회논문집
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• 한국재료학회 1994년도 추계 학술발표 강연 및 논문 개요집
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• pp.170-170
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• 1994

• 소음진동
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• 제7권3호
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• pp.499-509
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• 1997

During the process of oxide removal from work rolls in sheet metal manufacture, filamentary brushes frequently exhibit a bouncing or chatter behavior. The dynamics of this phenomenon is investigated through the development of expressions for the non-linear contact stiffness between the brush and the roll. With formulation of simple structural models, the time responses in the presence and absence of friction under random excitation are investigated. Possible solutions for the minimization or avoidance of this bouncing or chatter problem are also suggested.

• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2010년도 춘계학술대회 초록집
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• pp.91.2-91.2
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• 2010

The use of plated front contact for metallization of silicon solar cell may alternative technologies as a screen printed and silver paste contact. This technologies should allow the formation of contact with low contact resistivity a high line conductivity and also reduction of shading losses. The better performance of Ni/Cu contacts is attributed to the reduced series resistance due to better contact conductivity of Ni with Si and subsequent electroplating of Cu on Ni. The ability to pattern narrower grid lines for reduced light shading combined with the lower resistance of a metal silicide contact and improved conductivity of plated deposit. This improves the FF as the series resistance is deduced. This is very much required in the case of low concentrator solar cells in which the series resistance is one of the important and dominant parameter that affect the cell performance. A selective emitter structure with highly dopes regions underneath the metal contacts, is widely known to be one of the most promising high-efficiency solution in solar cell processing. This paper using selective emitter structure technique, fabricated Ni/Cu plating metallization cell with a cell efficiency of 17.19%.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2009년도 하계학술대회 논문집
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• pp.444-445
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• 2009

The metallic contact system of silicon solar cell must have several properties, such as low contact resistance, easy application and good adhesion. Ni is shown to be a suitable barrier to Cu diffusion as well as desirable contact metal to silicon. Nickel monosilicide(NiSi) has been suggested as a suitable silicide due to its lower resistivity, lower sintering temperature and lower layer stress than $TiSi_2$. Copper and Silver can be plated by electro & light-induced plating method. Light-induced plating makes use the photovoltaic effect of solar cell to deposit the metal on the front contact. The cell is immersed into the electrolytic plating bath and irradiated at the front side by light source, which leads to a current density in the front side grid. Electroless plated Ni/ Electro&light-induced plated Cu/ Light-induced plated Ag contact solar cells result in an energy conversion efficiency of 16.446 % on $0.2\sim0.6\;{\Omega}{\cdot}cm$, $20\;\times\;20\;mm^2$, CZ(Czochralski) wafer.

• Tribology and Lubricants
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• 제30권2호
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• pp.99-107
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• 2014

Fretting corrosion tests are conducted with a constant displacement amplitude using silver-plated brass coupons to investigate the effect of contact pressure on fretting corrosion. Three behaviors are identified based on the change in electric resistance and friction coefficient during the fretting test period, and the identified behaviors are dependent on the magnitude of the applied load. The failure cycle ($N_f$) with an electric resistance of 0.1 D cannot be achieved due to the adhesion behavior of the metal and metal contact under the higher applied load of 0.45 N. This suggests that an average contact pressure higher than 159 MPa for the silver-coated connector is desirable to gain an almost infinite lifetime. The relationship between the electric contact resistance (R) and the average contact pressure (p) can be written as $p=106.2{\times}{\Omega}^{-1.5}$.

• 전기학회논문지
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• 제60권1호
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• pp.85-92
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• 2011

Main characteristic in railroad is the guided movement of the wheel by the track through a metal-to-metal contact, conferring to the rail vehicle a single degree of freedom. There are defects such as head check, shelling, corrugation, squats etc in surface of the rail by interface between the wheel and rail. These defects bring about reducing the life-cycle of rails and track components and increasing noises. In case of bad conditions, it is possible to happen to full-scale accident such as derailment. Recently, the track capacity has been increased for increasing speed and operation efficiency. So, maintenance and indirect cost have been increased. Currently, a coating method of rail construction is proposed by using the ceramics in Korea. Rails are used as the earth in electrical railroad systems. Currently traction return current is flowed through wheels of trains. In case of rails coated, problems are caused in the contact power between wheel and coating material of spray. In this paper, electric model is presented in the AT feeding method. In case of rails coated, electric model is presented. Also, standard resistance of the ceramic is demonstrated by contact power between wheel and coating material of spray.