• 항공우주시스템공학회지
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• 제16권3호
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• pp.73-83
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• 2022

본 논문에서는 항공기 운영 중에 RF 방사 신호로 인하여 발생한 특정 주파수 대역 대의 수신 잡음에 대한 개선 방안을 연구하였다. 항공기의 통신장비는 내/외부통신의 기능을 담당하기에 비행 임무 수행과 안전에 있어서 매우 중요하다. 잡음이 없고 깨끗한 통신 품질과 송/수신 기능이 구현되어야 한다. 따라서 특정 주파수 대역 대의 수신 잡음 현상을 고장탐구를 통해 원인분석을 하였다. 항공기 내부의 특정 보조시스템 장비에서 발산되는 RF 방사 신호로 인해 발생한 수신 잡음을 무전해 니켈 도금이 적용된 CAP으로 차폐하여 개선하였다. 또한, 개선 방안에 대한 측정 및 검증 결과도 함께 기술하였다.

• 공업화학
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• 제8권5호
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• pp.742-748
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• 1997

초경공구(WC-Co)의 성능 향상을 목적으로 고경도, 높은 열전도도의 특성 등을 가진 다이아몬드 막을 코팅하고 있으나 WC-Co 기판표면의 특성상 문제점으로 인하여 코팅의 어려움이 있다. 이 문제의 해결을 위하여 WC-Co기판위에 중간층을 도입한 후 다이아몬드 막을 증착시키는 새로운 방법을 고려하였으며 중간층의 제조에 무전해 Ni-P도금법을 사용하였다. 무전해도금을 위한 WC-Co기판의 전처리, 무전해도금 및 열처리, 다이아몬드 막 증착의 공정에 대하여 조사하였다. 형성되는 계면의 구조와 성분, 계면간의 밀착력 등을 Scratch Tester, Roughness Tester, SEM/EDS, XRD, Raman Spectroscopy를 사용하여 분석하였다. 무전해도금의 전처리로서 산에 의한 방법과 다이아몬드 분말에 의한 방법을 사용하였으며 두 경우에 모두 WC-Co기판의 표면조도의 감소, 표면 Co성분의 감소, 그리고 밀착력 저하가 관찰되었다. 무전해도금층의 열처리시 영향을 조사하였으며 온도 증가에 따라 Ni 결정이 형성되며 이로 인하여 도금의 밀착력이 증가되며 Ni 결정이 성장함을 관찰하였다. 또한 열처리된 Ni-P도금 위에서 다이아몬드막 증착 실험을 실시하였으며 증착온도를 증가시킴에 따라 다이아몬드 형성이 증가되어 $800^{\circ}C$일때 양호한 다이아몬드 막을 얻을 수 있었다. 본 연구의 방법 및 실험조건은 WC-Co를 비롯하여 다이아몬드 막 형성이 어려운 소재들의 코팅에 효과적으로 이용될 수 있다.

• Corrosion Science and Technology
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• 제8권1호
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• pp.15-20
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• 2009

Surface of PEEK(poly-ether-ether-ketone) was modified by chemical etching, plasma treatment and mechanical grinding to improve the plating adhesion. The plating characteristics of these samples were studied by the contact angle, plating thickness, gloss and adhesion. Chemical etching and plasma treatment increased wettability, adhesion and gloss. The contact angle of as-received PEEK was $61^{\circ}$. The contact angles of chemical etched, plasma treated or both were improved to the range of $15{\sim}33^{\circ}$. In the case of electroless plating, the thickest layer without blister was $1.6{\mu}m$. The adhesion strengths by chemical etching, plasma treatment or both chemical etching and plasma treatment were $75kgf/cm^2$, $102kgf/cm^2$, $113kgf/cm^2$, respectively, comparing to the $24kgf/cm^2$ of as-received. In the case of mechanically ground PEEKs, the adhesion strengths were higher than those unground, with the sacrifice of surface gloss. The gloss of untreated PEEK were greater than mechanically ground PEEKs. Plating thickness increased linearly with the plating times.

• Current Photovoltaic Research
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• 제4권4호
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• pp.140-144
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• 2016

In this paper, core-shell structure of nickel/gold (Ni/Au) conductive layer on poly-methyl-methacrylate (PMMA) micro-ball was fabricated and its conduction property was investigated. Firstly, PMMA micro-ball was synthesized by using dispersion polymerization method. Size of the ball was $2.8{\mu}m$ within ${\pm}7%$ deviation, and appropriate elastic deformation of the PMMA micro-ball ranging from 31 to 39% was achieved under 3 kg pressure. Also, 200 nm thick Ni/Au conductive layer was fabricated on the PMMA micro-ball by uniformly depositing with electroless-plating. Adhesion of the conductive layer was optimized with help of surface pre-treatment, and the layer adhered without peeling-off despite of thermal expansion by collision with accelerated electrons. Composite paste containing core-shell structured particles well cured at low temperature of $130^{\circ}C$ while pressing the test chip onto the substrate to make electrical contact, and electrical resistance of the conductive layer showed stable behavior of about $6.0{\Omega}$. Thus, it was known that core-shell structured particle of the Ni/Au conductive layer on PMMA micro-ball was feasible to flexible electronics.

• 한국분말재료학회지
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• 제25권5호
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• pp.375-378
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• 2018

Conductive and dielectric SiC are fabricated using electroless plating of Ni-Fe films on SiC chopped fibers to obtain lightweight and high-strength microwave absorbers. The electroless plating of Ni-Fe films is achieved using a two-step process of surface sensitizing and metal plating. The complex permeability and permittivity are measured for the composite specimens with the metalized SiC chopped fibers dispersed in a silicone rubber matrix. The original non-coated SiC fibers exhibit considerable dielectric losses. The complex permeability spectrum does not change significantly with the Ni-Fe coating. Moreover, dielectric constant is sensitively increased with Ni-Fe coating, owing to the increase of the space charge polarization. The improvements in absorption capability (lower reflection loss and small matching thickness) are evident with Ni-Fe coating on SiC fibers. For the composite SiC fibers coated with Ni-Fe thin films, a -35 dB reflection loss is predicted at 7.6 GHz with a matching thickness of 4 mm.

• 마이크로전자및패키징학회지
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• 제30권1호
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• pp.49-54
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• 2023

최근 SIP (System in Packaging) 기술은 고주파(5G 이상) 통신 및 미세 피치 회로 특성을 만족해야 한다. 기존 ENIG (Electroless Ni/Immersion Au Plating) 표면처리는 전송 손실이 증가하여 고주파에 적합하지 않으므로, 니켈 도금층이 없어도 패턴 및 패드의 신뢰성 수준을 만족시킬 수 있는 표면 처리 기술이 검토되고 있다. 본 논문에서는 고주파 통신 대응을 위한 Ni-less 표면처리기술과 소재에 따른 주파수 특성 등에 대한 연구 동향을 조사하였다.

• 한국재료학회지
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• 제5권8호
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• pp.1013-1019
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• 1995

본 연구에서는 무전해 도금범으로 polyester film 상에 Co-Ni-P 박막을 석출시키고, pH, 온도 그리고 도금용액의 농도에 따른 도금속도 및 석출된 도금박막의 합금조성과 합금조성에 따른 자기적 특성을 고찰하였다. 무전해도금의 석출속도는 pH 8.5, 온도 90℃일때 가장 좋았으며, 자기적 특성도 이 때가 가장 좋았다. 합금조성은 pH와 착화제의 농도에 따라서는 크게 변화하였으나, 그 밖의 인자들에 의해서는 변화하지 않았다. 최적조건에서 만들어진 박막의 합금조성은 코발트가 78%, 니켈이 16%, 인이 6%였고, 보자력은 370 Oe, 각형비는 0.65였다. 박막은 합금조성에 따라 경질자성막과 연질자성막의 두가지 형태로 변화했고, 니켈이 30% 이상 공석(共席)되었을 때, 연질자성막으로 되었다. 연질자성막일때, 합금박막의 결정구조는 니켈이 강하게 배향된 비정질 형태를 나타냈고, 경질자성 막일때는, 코발트(101)과 (100)면으로 배향된 α-코발트의 hcp 결정구조를 나타내었다.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2007년도 하계학술대회 논문집 Vol.8
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• pp.192-193
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• 2007

An evaporated Ti/Pd/Ag contact system is most widely used to make high-efficiency silicon solar cells, however, the system is not cost effective due to expensive materials and vacuum techniques. Commercial solar cells with screen-printed contacts formed by using Ag paste suffer from a low fill factor and a high shading loss because of high contact resistance and low aspect ratio. Low-cost Ni and Cu metal contacts have been formed by using electro less plating and electroplating techniques to replace the Ti/Pd/Ag and screen-printed Ag contacts. Ni/Cu alloy is plated on a silicon substrate by electro-deposition of the alloy from an acetate electrolyte solution, and nickel-silicide formation at the interface between the silicon and the nickel enhances stability and reduces the contact resistance. It was, therefore, found that nickel-silicide was suitable for high-efficiency solar cell applications. Cu was electroplated on the Ni layer by using a light induced plating method. The Cu electroplating solution was made up of a commercially available acid sulfate bath and additives to reduce the stress of the copper layer. In this paper, we investigated low-cost Ni/Cu contact formation by electro less and electroplating for crystalline silicon solar cells.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2005년도 춘계학술대회 논문집
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• pp.1507-1510
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• 2005

This study was carried out as a part of the research on the development of a maskless and electroless process for fabricating metal micro/nanostructures by using a nanoindenter and an electroless deposition technique. $2-\mu{m}-deep$ indentation tests on Ni and Cu samples were performed. The elastic recovery of the Ni and Cu was 9.30% and 9.53% of the maximum penetration depth, respectively. The hardness and the elastic modulus were 1.56 GPa and 120 GPa for Ni and 1.49 GPa and 100 GPa for Cu. The effect of single-point diamond machining conditions such as the Berkovich tip orientation (0, 45, and $90^{\circ}$) and the normal load (0.1, 0.3, 0.5, 1, 3, and 5 mN), on both the deformation behavior and the morphology of cutting traces (such as width and depth) was investigated by constant-load scratch tests. The tip orientation had a significant influence on the coefficient of friction, which varied from 0.52-0.66 for Ni and from 0.46-0.61 for Cu. The crisscross-pattern sample showed that the tip orientation strongly affects the surface quality of the machined area during scratching. A selective deposition of Cu at the pit-like defect on a p-type Si(111) surface was also investigated. Preferential deposition of the Cu occurred at the surface defect sites of silicon wafers, indicating that those defect sites act as active sites for the deposition reaction. The shape of the Cu-deposited area was almost the same as that of the residual stress field.

• 한국태양에너지학회:학술대회논문집
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• 한국태양에너지학회 2009년도 춘계학술발표대회 논문집
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• pp.230-234
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• 2009

It is significant technique to increase competitiveness that solar cells have a high energy conversion efficiency and cost effectiveness. When making high efficiency crystalline Si solar cells, evaporated Ti/Pd/Ag contact system is widely used in order to reduce the electrical resistance of the contact fingers. However, the evaporation process is no applicable to mass production because high vacuum is needed. Furthermore, those metals are too expensive to be applied for terrestrial applications. Ni/Cu/Ag contact system of silicon solar cells offers a relatively inexpensive method of making electrical contact. Ni silicide formation is one of the indispensable techniques for Ni/Cu/Ag contact sytem. Ni was electroless plated on the front grid pattern, After Ni electroless plating, the cells were annealed by RTP(Rapid Thermal Process). Ni silicide(NiSi) has certain advantages over Ti silicide($TiSi_2$), lower temperature anneal, one step anneal, low resistivity, low silicon consumption, low film stress, absence of reaction between the annealing ambient. Ni/Cu/Ag metallization scheme is an important process in the direction of cost reduction for solar cells of high efficiency. In this article we shall report an investigation of rapid thermal silicidation of nickel on silngle crystalline silicon wafers in the annealing range of $350-390^{\circ}C$. The samples annealed at temperatures from 350 to $390^{\circ}C$ have been analyzed by SEM(Scanning Electron Microscopy).