• The Transactions of The Korean Institute of Electrical Engineers
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• v.57 no.12
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• pp.2276-2280
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• 2008

In this paper, we present thermal dependancy of LED package element by changing temperature of MCPCB for design high efficiency LED lamp, and confirmed influence of LED chip against temperature with analysis of thermal resistance and thermal capacitance. As increasing temperature, WPOs were decreased from 25 to 22.5 [%] and optical power were also decreased. that is decreased reason of optical power that forward voltage was declined by decrease of energy bandgap. Therefore optical power by temperature of MCPCB should consider to design lamp for street light and security light. Moreover, compensation from declined optical efficiency is demanded when LED package is composed. Also, thermal resistances from chip to metal PCB were decreased from 12.18 to 10.8[$^{\circ}C/W$] by changing temperature. Among the thermal resistances, the thermal resistance form chip to die attachment was decreased from 2.87 to 2.5[$^{\circ}C/W$] and was decreased 0.72[$^{\circ}C/W$] in Heat Slug by chaning temperature. Therefore, because of thermal resistance gap in chip and heat slug, reliability and endurance of high power LED affect by increasing non-radiative recombination in chip from heat.

• Proceedings of the IEEK Conference
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• 2003.07e
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• pp.2375-2378
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• 2003

In manufacture of printed circuit boards, one important issue is precisely to measure the three-dimensional shape of the solder paste silk-screened prior to direct surface mounting of chips. This paper presents the 3D shape reconstruction of solder paste using the optical triangulation method based on structured light or slit beam and the measurement algorithm for height, volume. area, and coplanarity on component pads from the 3D range image. Futhermore, statistical process control function is incorporated for process capability analysis.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1995.04b
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• pp.371-376
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• 1995

Computer vision is applicated to measure the position and orientation of the SMD on 8mm Camcoder PCB and advanced image processing algorithms for high accuracy and real time processing are proposed. Illumination conditions are optimized for the best image formation and a set of LEDs is used as economic illuminator, which is regarded as a summation of many point sources. Conctete optical system is constructed and the performance of the proposed algorithm is verified by several experiments.

• Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
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• 2009.05a
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• pp.157-159
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• 2009

LED BLU(Back Light Unit), based on MCPCB(Metal Core Printed Circuit Board) with anodizing oxide dielectric layer and improved thermal dissipation property, are presented. Reflecting cups were also formed on the surface of the MCPCB such that optical coupling between neighboring chips were minimized for improving the photon extraction efficiency. LED chips were directly attached on the MCPCB by using the COB (Chip On Board) scheme.

• JSTS:Journal of Semiconductor Technology and Science
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• v.14 no.4
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• pp.443-450
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• 2014

This paper presents a 20-Gb/s optical receiver circuit fabricated with standard 65-nm CMOS technology. Our receiver circuits are designed with consideration for parasitic inductance and capacitance due to bonding wires connecting the photodetector and the circuit realized separately. Such parasitic inductance and capacitance usually disturb the high-speed performance but, with careful circuit design, we achieve optimized wide and flat response. The receiver circuit is composed of a transimpedance amplifier (TIA) with a DC-balancing buffer, a post amplifier (PA), and an output buffer. The TIA is designed in the shunt-feedback configuration with inductive peaking. The PA is composed of a 6-stage differential amplifier having interleaved active feedback. The receiver circuit is mounted on a FR4 PCB and wire-bonded to an equivalent circuit that emulates a photodetector. The measured transimpedance gain and 3-dB bandwidth of our optical receiver circuit is 84 $dB{\Omega}$ and 12 GHz, respectively. 20-Gb/s $2^{31}-1$ electrical pseudo-random bit sequence data are successfully received with the bit-error rate less than $10^{-12}$. The receiver circuit has chip area of $0.5mm{\times}0.44mm$ and it consumes excluding the output buffer 84 mW with 1.2-V supply voltage.

• The Optical Journal
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• s.135
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• pp.73-73
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• 2011

한국 광학산업을 상징하는 글로벌 산업단체 한국광학기기협회(www.koia.or.kr)가 2012년 4월11일부터 13일까지 서울 코엑스에서 제1회 광전자 산업전시회를 개최한다. 한국광학기기협회와 케이훼어스(주)가 공동 주최하는 'Photonics Seoul 2012'는 광부품 소재, 레이저 및 레이저응용장비, 광학측정 및 시험분석장비, 정밀영상시스템, IT정보기기, 소프트웨어 및 녹색광산업 분야의 광학장비 및 부품소재 등 광산업 제품을 총 망라하는 대규모 전시회라는 점에서 기대를 모으고 있다. 특히 이 전시회는 국내 광산업체의 비즈니스 활성화를 위해 'SMT/PCB & NEPCON KOREA', 'Printed Electronic & Electronics Materials Show', 'LED Packaging EXPO', 'Film Technology Show' 전시회와 동시 개최되어 전시기간 동안 한자리에서 최신 기술 및 제품 동향은 물론, 다양한 국내외 바이어를 만날 수 있는 기회가 될 것으로 기대된다. 동 전시회에 대한 자세한 사항은 한국광학기기협회 사업추진팀(02-3481-8931)으로 연락하면 된다.

• The Optical Journal
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• s.124
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• pp.28-32
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• 2009

초정밀 초고속 레이저 가공공정 및 장비는 유연소재의 태양전지, 인쇄전자소자(printed electronics devices)의 초고속 절단공정, 고기능 다기능 모바일 기기용 고부가 PCB의 초정밀 초고속 레이저 드릴링 및 복합 유연 가공 등에 적용된다. 최근 레이저 가공기 연구개발 패러다임은 레이저 의존형 장비 개발에서 레이저 맞춤형 장비 개발로 변화되고 있다. 즉, 수입된 레이저 발진기 및 광학기기를 사용하여 레이저 공정 및 장비를 개발하는 방식에서 벗어나, 개발하고자 하는 공정 및 장비에 최적화된 레이저 발진기 개발을 병행하는 것이다. 이러한 상황에서 최근 지식경제부 산업원천기술개발사업으로 신개념 레이저 기반 초정밀 초고속 가공시스템 개발이 착수되었으며, 본 고에서는 이에 대한 전반적인 내용들 소개하고자 한다.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.21 no.1
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• pp.1-11
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• 1997

Austomated visual inspection(AVI) capability has become an important key component in the automated manufacturing system. In such a visual inspection system an intensity(or color) image of a scene is quickly affected by optical property of objects, condition and roughness of surface, lens and filters, image sensor property and lighting system. In particular, the lighting system disign is the most important factor, since it affects overall performance of the visual system. For fast and cheap automated visual inspection system it is important to obtain the good image quality which results from careful attention to the design of the lighting system. In this paper, the lighting subsystem of AVI system is analysed for the inspection of printed circuit board(PCB) patterns. The spectral reflectance of materials, which are composed of PCB, is measured for choosing the light source. The reflection property is theoretically obtained by a reflection model and also obtained by experiments which measure intensity with varying the viewing direction of image sensor and the lighting direction of illuminator. The illumination uniformity of a ring-type illuminator. The lighting system is designed based upon the experimental results and theoretial analysis.

• Korean Journal of Optics and Photonics
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• v.20 no.2
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• pp.134-140
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• 2009

In this study, the influence of surface roughness on light scattering from Au pads on a PCB surface was investigated. Angular distributions of light scattered from Au pads with different surface roughness were measured for several incident angles. Diffusely-scattered light could be separated by using the fact that the amount of specularly-scattered light was directly related to surface roughness. The separated diffuse term was curve-fitted with a physics-based model, and then the related scattering parameters were extracted and compared with measured parameters.

• Proceedings of the Korean Vacuum Society Conference
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• 2013.02a
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• pp.323-323
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• 2013

High power light-emitting diodes (LEDs) are widely used in many device applications due to its ability to operate at high power and produce high luminance. However, releasing the heat accumulated in the device during operating time is a serious problem that needs to be resolved to ensure high optical efficiency. Ceramic or Aluminium base metal printed circuit boards are generally used as integral parts of communication and power devices due to its outstanding thermal dissipation capabilities as heat sink or heat spreader. We investigated the characterisation of electroless plating of Ni-B film according to plating bath temperature, ranging from $50^{\circ}C$ to $75^{\circ}C$ on Ag paste/anodised Al ($Al_2O_3$)/Al substrate to be used in metal PCB for high power LED packing systems. X-ray diffraction (XRD), Field-Emission Scanning Electron Microscopy (FE-SEM) and X-ray Photoelectron Spectroscopy (XPS) were used in the film analysis. By XRD result, the structure of the as deposited Ni-B film was amorphous irrespective of bath temperature. The activation energy of electroless Ni-B plating was 59.78 kJ/mol at the temperature region of $50{\sim}75^{\circ}C$. In addition, the Ni-B film grew selectively on the patterned Ag paste surface.