• 한국전자파학회논문지
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• 제19권3호
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• pp.366-375
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• 2008

일반적으로 고속의 디지털부와 아날로그부의 귀환 전류 평면(Return Current Plane: RCP)은 분할된다. 이것은 PCBs(Printed Circuit Boards)에서 각 서브 시스템 사이의 노이즈가 서로 간섭을 일으키지 않도록 하기 위해 이루어지지만, 각 서브 시스템 사이에 연결된 신호선이 존재하는 경우, 이러한 분할은 원치 않는 효과를 발생시킨다. RCP의 분할은 회로적인 측면에서 신호 무결성(Signal Integrity)에 악영향을 미치고, EMI(Electromagnetic Interference) 측면에서 전자파의 복사 방출을 증가시키는 주된 요인이 된다. 이러한 신호 무결성을 유지하기 위한 방법으로 component bridge(저항 브릿지, 커패시터 브릿지, 페라이트 브릿지 등: CB)가 사용되고 있지만 아직 정확한 CB의 사용 지침이 부족한 실정이다. 본 논문에서는 신호 무결성 측면에서 다중-CB 사용 방법에 대한 설계 원리를 측정과 시뮬레이션을 통해 분석하고 노이즈 저감 방법에 대한 설계 방법을 제시하고자 한다. 일반적으로 CB, 사이의 간격은 ${\lambda}/20$로 페라이트 비드(ferrite bead)를 사용하도록 권장하고 있다. 본 논문은 CB의 다중 연결시 페라이트 비드와 칩 저항에 대한 설계 방법을 측정과 시뮬레이션을 통하여 증명하였고, 다중 연결된 칩 저항$(0{\Omega})$이 신호 무결성 측면에서 더욱 더 효과적인 설계 방법임을 증명하였다.

• 한국재료학회지
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• 제12권9호
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• pp.750-760
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• 2002

In this study, three solders, Sn-37Pb, Sn-3.5Ag, and Sn-3.8Ag-0.7Cu were screen printed on both electroless Ni/Au and OSP metal finished micro-via PCBs (Printed Circuit Boards). The interfacial reaction between PCB metal pad finish materials and solder materials, and its effects on the solder bump joint mechanical reliability were investigated. The lead free solders formed a large amount of intermetallic compounds (IMC) than Sn-37Pb on both electroless Ni/Au and OSP (Organic Solderabilty Preservatives) finished PCBs during solder reflows because of the higher Sn content and higher reflow temperature. For OSP finish, scallop-like $Cu_{6}$ /$Sn_{5}$ and planar $Cu_3$Sn intermetallic compounds (IMC) were formed, and fracture occurred 100% within the solder regardless of reflow numbers and solder materials. Bump shear strength of lead free solders showed higher value than that of Sn-37Pb solder, because lead free solders are usually harder than eutectic Sn-37Pb solder. For Ni/Au finish, polygonal shaped $Ni_3$$Sn_4$ IMC and P-rich Ni layer were formed, and a brittle fracture at the Ni-Sn IMC layer or the interface between Ni-Sn intermetallic and P-rich Ni layer was observed after several reflows. Therefore, bump shear strength values of the Ni/Au finish are relatively lower than those of OSP finish. Especially, spalled IMCs at Sn-3.5Ag interface was observed after several reflow times. And, for the Sn-3.8Ag-0.7Cu solder case, the ternary Sn-Ni-Cu IMCs were observed. As a result, it was found that OSP finished PCB was a better choice for solders on PCB in terms of flip chip mechanical reliability.

• 자원리싸이클링
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• 제16권2호
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• pp.63-76
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• 2007

현재 우리나라 미이용자원의 대표격으로서 전기로 제강분진(EAF Dust)중의 아연(Zn)과 석유탈황폐촉매 중의 몰리브덴(Mo)과 바나듐(V)등을 들 수 있다. 자동차 폐촉매로부터 백금족금속(PGM) 회수 및 폐프린트 회로기판(PCBs)부터의 금, 은, 등도 거론할 수 있으나 유통경로가 복잡하여 정확한 회수통계 파악이 어렵다. 본고에서는 이들 금속의 우리나라에서의 연구동향을 조사 검토하였다. 물질흐름에 관해서는 석유탈황폐촉매에서 회수할 수 있는 Mo, V및 Ni에 한해서만 조사하였다. 그리고 EAF Dust중의 Zn 에 관해서는 후일 별도로 논술하려고 한다. 다만 금속시세가 폭등하고 있기 때문에 금년(2007)내로 Mo및 V의 회수가 확실시되고, 아연도 회수될 전망이다.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 1997년도 한국자동제어학술회의논문집; 한국전력공사 서울연수원; 17-18 Oct. 1997
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• pp.1742-1745
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• 1997

We have developed a highly responsible probing system for inspection of electrical properties of assemble PCB$_{s}$ (printed circuit boards). However, as the duration of the impact occurring between a probe and a solder joint on PCB is very short, it is very difficult to control the harmful peak impact force and the slip motion of the probe to sufficient level only by its vorce feedback control with high gains. To overcome these disadvantages of the prototype, it needs ot obtain some information of the solder joint in advance before the contact. In addition, to guarantee the reliability of the probing task, the probing system is required to measure several points around the probale target point at high speed. There fore, to meet such requirements, we propose a new noncontaet sensor capable of detecting simultaneously position and normal vectors of the multiple points around the probable target point in real time. By using this information, we can prepare a control strategy for stable contact motion on impact. In this paper, we described measuring priniciple, design, and development of the sensor. The effectiveness of the proposed sensor is verified through a series of experiments.s.

• 문화기술의 융합
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• 제4권3호
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• pp.209-212
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• 2018

이방성 도전필름(ACF)을 사용한 본딩은 납땜이 용이하지 않은 이질적인 소재 간 미세 접합을 형성하는데 널리 사용되어진다. 성공적인 ACF 본딩 구현을 위한 3가지 제한조건이 존재한다. 본딩 접촉점은 설정된 작업 시간동안 적절한 압력과 온도를 유지한 헤드에 의해서 압착되어야 한다. 본 논문에서는 머신 비전을 기반으로 한 ACF 본딩기법을 제안하고 실험을 통해 검증한다. 시스템은 본딩 작업대 상의 PCB 위치 및 방향을 계산하고 헤드가 압착되어야 하는 최적의 접촉점을 결정한다. 제안한 시스템이 접촉면 상의 헤드 평탄도를 보장함으로써 접착력을 향상시킬 수 있음을 실험결과를 통해 보여준다.

• 제어로봇시스템학회논문지
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• 제6권8호
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• pp.710-718
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• 2000

In this paper we described an approach to automation of visual inspection of solder joint defects of SMC(Surface Mounted Components) on PCBs(Printed Circuit Board) by using neural network and fuzzy rule-based classification method. Inherently the surface of the solder joints is curved tiny and specular reflective it induces difficulty of taking good image of the solder joints. And the shape of the solder joints tends to greatly vary with the soldering condition and the shapes are not identical to each other even though the solder joints belong to a set of the same soldering quality. This problem makes it difficult to classify the solder joints according to their qualities. Neural network and fuzzy rule-based classification method is proposed to effi-ciently make human-like classification criteria of the solder joint shapes. The performance of the proposed approach is tested on numerous samples of commercial computer PCB boards and compared with the results of the human inspector performance and the conventional Kohonen network.

• 전기학회논문지
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• 제66권10호
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• pp.1508-1515
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• 2017

This paper proposes the defect detection method for automatic inspection machines in printed circuit boards (PCBs) manufacturing system. The defects of PCB such as open, short, pin hole and scratch can be detected by comparing the standard image and the target image. The standard image is obtained from CAD file such as ODB++ format, and the target image is obtained by arranging, filtering and binarization of captured PCB image. Since the PCB size is too large and image resolution is too high, the image processing requires a lot of memory and computational time. The wavelet transform is applied to compress the standard and target images, which results in reducing the memory and computational time. To increase the inspection accuracy, we utilize the he HH-domain as well as LL-domain of the transformed images. Experimental results are finally presented to show the performance improvement of the proposed method.

• 자원리싸이클링
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• 제21권5호
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• pp.3-17
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• 2012

암모니아 습식제련공정은 철과 칼슘의 용해를 억제하며 구리 등의 금속을 선택적으로 침출이 가능한 장점이 있어 구리, 금, 니켈 및 코발트 등의 금속을 선택적으로 침출하기 위한 연구가 수행되어왔다. 이 글에서는 모터스크랩과 폐인쇄회로기판으로부터 구리의 선택적 침출, 티오황산염 사용 등 시안의 대체 및 저감을 위한 금의 암모니아침출, 산화니켈광 및 망간단괴처리공정 중간산물로부터 니켈과 코발트를 회수하기 위한 암모니아침출 기술개발동향을 정리하고 국내 연구개발방향을 제시하고자 하였다.

• Journal of information and communication convergence engineering
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• 제14권4호
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• pp.252-257
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• 2016

An edge-located electromagnetic bandgap (EL-EBG) structure using a defected ground structure (DGS) is proposed to suppress resonant modes induced by edge excitation in a two-dimensional planar parallel plate waveguide (PPW). The proposed EL-DGS-EBG PPW significantly mitigates multiple transverse-magnetic (TM) modes in a wideband frequency range corresponding to an EBG stopband. To verify the wideband suppression, test vehicles of a conventional PPW, a PPW with a mushroom-type EBG structure, and an EL-DGS-EBG PPW are fabricated using a commercial process involving printed circuit boards (PCBs). Measurements of the input impedances show that multiple resonant modes of the previous PPWs are significantly excited through an input port located at a PPW edge. In contrast, resonant modes in the EL-DGS-EBG PPW are substantially suppressed over the frequency range of 0.5 GHz to 2 GHz. In addition, we have experimentally demonstrated that the EL-DGS-EBG PPW reduces the radiated emission from -24 dB to -44 dB as compared to the conventional PPW.

• 한국전기전자재료학회논문지
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• 제22권6호
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• pp.495-500
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• 2009

The ceramic($BaTiO_3$)-polymer(epoxy) composites have been widely investigated as dielectric materials for embedded capacitors in printed circuit boards (PCBs). The dielectric properties of $BaTiO_3$/epoxy composites prepared using the agglomerated $BaTiO_3$ particles were investigated in the present study. The dielectric constants of the composites prepared using the agglomerated $BaTiO_3$ particles were about 2 times higher than those of the composites with the dispersed $BaTiO_3$ particles. The insulation resistance of the composites prepared using the agglomerated $BaTiO_3$ particles were lower than those of the composites with dispersed $BaTiO_3$ particles. As a result, there is tradeoff between high dielectric constant and insulation resistance in the $BaTiO_3$/epoxy composites. So it is important to select proper agglomerated or dispersed $BaTiO_3$ particles in accordance with needs.