• Journal of electromagnetic engineering and science
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• 제14권1호
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• pp.1-8
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• 2014

A differential-cascode CMOS power amplifier (PA) with a supply modulator for envelope tracking (ET) has been implemented by 0.18 ${\mu}m$ RF CMOS technology. The loss at the output is minimized by implementing the output transformer on a FR-4 printed circuit board (PCB). The CMOS PA utilizes the $2^{nd}$ harmonic short at the input to enhance the linearity. The measurement was done by the 10MHz bandwidth 16QAM 6.88 dB peak-to-average power ratio long-term evolution (LTE) signal at 1.85 GHz. The ET operation of the CMOS PA with the supply modulator enhances the power-added efficiency (PAE) by 2.5, to 10% over the stand-alone CMOS PA for the LTE signal. The ET PA achieves a PAE of 36.5% and an $ACLR_{E-UTRA}$ of -32.7 dBc at an average output power of 27 dBm.

• Journal of electromagnetic engineering and science
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• 제10권3호
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• pp.179-182
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• 2010

This paper proposed a novel compact bandpass filter with folded half mode substrate integrated waveguide (FHMSIW) cavities using two-layer printed circuit board(PCB) process. The area of the FHMSIW filter is reduced by nearly 50 % and 75 % compared with half mode substrate integrated waveguide(HMSIW) filter and substrate integrated waveguide(SIW) filter, respectively. A four-pole Chebyshev FHMSIW bandpass filter at C-band has been designed, simulated and fabricated. Measured results are presented and found to agree with the full-wave simulated results by using Ansoft HFSS. The filter shows good performance and compact size.

• 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.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2011년도 제42회 하계학술대회
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• pp.1678-1679
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• 2011

고속/고전압으로 동작하는 자동차 전장품에 대한 EMI/EMC(Electromagnetic Interfere / Electromagnetic Compatibility) 문제는 기존의 PCB(Printed Circuit Board)에서의 문제와 다르며 하이브리드/전기 자동차에서 중요하게 다뤄지는 배터리에 대한 최적화 된 모델링 방법이 본 논문에 소개 되어있다. 기존의 단순한 저항과 커패시터의 연결로 표현 된 모델링이 아닌 고주파를 반영 할 수 있는 모델링 방법을 사용하였다. 이를 분석하기 위해 ANSYS사의 Simplorer와 Matlab을 사용해서 결과를 보았다. 본 논문에서는 DOD(Depth Of Discharge)에 따른 통합 등가회로 모델을 구현하면서 기존의 단순한 지수함수 곡선적합(Curve fitting)이 아닌 SOC(State Of Charge)의 경계조건을 반영하여 정확성을 높였다. 이로써 실험 데이터를 이용해 배터리 등가회로 모델링을 하여 정확한 배터리 동작의 해석을 할 수 있고 이에 따른 전도성 방사(CE : Conducted Emission)문제에 보다 쉽게 접근 할 수 있다.

• 한국신뢰성학회지:신뢰성응용연구
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• 제5권2호
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• pp.261-272
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• 2005

In evaluation of electronic reliability on the PCB(Printed Circuit Board), electrochemical migration is one of main test objects. The phenomenon of electrochemical migration occurs In the environment of the high humidity and the high temperature under bias through a continuous aqueous electrolyte. In this paper, the generating mechanism of electrochemical migration is investigated by using water droll acceleration test under various waters. The waters used in the water drop test are city water, distilled water and ionic water. It found that the generated velocity of electrochemical migration depended on the temperature of water and the electrolyte quantity which included in the various waters.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2008년도 추계학술대회 논문집 Vol.21
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• pp.202-202
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• 2008

The world gross market of many kinds of electronics, such as TV and mobile phone has been increasing rapidly these days. It is mainly caused by the amazing developments of IT technology during past decade and the changes of individual life style for the better. Thanks to the increases of electronics manufactured in quantity, much more electronic components such as MLCC (multi layer ceramic capacitor) and PCB (printed circuit board), which are our main products, have been needed as a consequence. Though it was reported that total market of electronic components exceeds several hundreds of billion dollars, there are many manufactures struggling for survival in the competition of electronics components. Then the recognition of quality as a key technology has spread and the efforts for high-yield production lines have been kept in many companies. In this paper, our efforts to eliminate the contamination of particles and the diffusion of some volatile organic compounds which is very harmful to workers at production line have been introduced.

• Macromolecular Research
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• 제14권4호
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• pp.430-437
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• 2006

The ultra-drawing process of an ultra high molecular weight polyethylene (UHMWPE) gel film was examined by incorporating linear low-density polyethylene (LLDPE) and $BaTiO_3$ nanoparticles. The effects of LLDPE and the draw ratios on the morphological development and mechanical properties of the nanocomposite membrane systems were investigated. By incorporating $BaTiO_3$ nanoparticles in the UHMWPE/LLDPE blend systems, the ultra-drawing process provided a highly extended, fibril structure of UHMWPE chains to form highly porous, composite membranes with well-dispersed nanoparticles. The ultra-drawing process of UHMWPE/LLDPE dry-gel films desirably dispersed the highly loaded $BaTiO_3$ nanoparticles in the porous membrane, which could be used to form multi-layered structures for electronic applications in various embedded, printed circuit board (PCB) systems.

• Journal of Power Electronics
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• 제11권4호
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• pp.527-532
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• 2011

Due to the need for improved fuel consumption and the trend towards increasing the electrical content in automobiles, integrated starter generator (ISG) systems are being considered by the automotive industry. In this paper, in order to change the conventional generator of a vehicle, a belt driven integrated starter generator is considered. The overall ISG system, the design considerations for the claw pole type AC electric machine and a low voltage very high current power stage implementation are discussed. Test data on the low voltage claw pole type machine is presented, and a large current voltage source DC/AC inverter suitable for low voltage integrated starter generator operation is also presented. A metal based PCB (Printed Circuit Board) power unit to attach the 4-parallel MOS-FETs is used to achieve extremely high current capability. Furthermore, issues related to the torque assistance during vehicle acceleration and the generation/regeneration characteristics are discussed. A prototype with the capability of up to 1000 A and 27 V is designed and built to validate the kilo-amp inverter.

• Journal of Welding and Joining
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• 제19권3호
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• pp.311-316
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• 2001

This paper presents that the affecting factors to the solderability and initial reliability. It is the factor that the coefficient of thermal expansion between package and PCB(Printed Circuit Board), the quantity of solder paste and reflow condition, and Au thickness of the solder ball pad on polyimide tape. As the reflow soldering condition for 48 ${\mu}BGA$ is changed, it is estimated that the quantity of Au diffusion at eutectic Sn-Pb solder surface and initial bonding strength of eutectic Sn-Pb solder and lead free solder. It is the result that quantitative measurement of Au diffusion quantity is difficult, but the shear strength of eutectic Sn-Pb solder joint is 842 mN at first reflow and increases 879 mN at third reflow. The major failure mode in solder is judged solder fracture. So, Au diffusion quantity is more affected by reflow temperature than by the reflow times.

• 대한용접접합학회:학술대회논문집
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• 대한용접접합학회 2005년도 추계학술발표대회 개요집
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• pp.225-227
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• 2005

Sn-8wt%Zn-3wt%Bi (이하, Sn-8Zn-3Bi) 솔더의 장기 신뢰성을 평가하기 위하여 열 충격 시험을 행하였다. 열 충격 시험은 $-40^{\circ}C$에서 $80^{\circ}C$범위에서 1000 사이클 동안 하였다. 접합 기판으로는 각각 OSP(Organic Solderability Preservative), Sn 그리고 Ni/Au 처리를 한 PCB(Printed Circuit Board) 패드를 사용하였다. 접합에 사용한 부품은 1608 Chip(Multi Layer Chip Capacitor, Chip Resistor) 으로 전극 부위에 Sn-37wt%Pb, Sn 도금하여 사용하였다. 솔더링 후 1608 Chip의 전단 강도와 솔더링부에서 미세조직 및 IMC(Inter Metallic Compound) 변화를 관찰하였다. 측정결과, Sn-8Zn-3Bi 솔더의 초기 전단 강도는 기판의 표면처리에 상관없이 약 40N 이상이었다. 그리고 열충격 시험 1000 사이클 후에는 모든 기판에서 2N 정도 약간의 강도 저하를 보였다.