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일반 형광등에 사용되는 글로우 스타터(Glow Starter)의 수명 예측
장웅주(Woong-Ju Jang),박경수(Kyung-Soo Park),김재중(Jae-Jung Kim),손영갑(Young-Kap Son),장석원(Seog-Weon Chang),곽계달(Kae-Dal Kwack) 대한기계학회 2007 대한기계학회 춘추학술대회 Vol.2007 No.10
This paper presents predicting an accelerated life test of glow starter for flourescent lamp by reliability tool ALTA(software). Failure mode/mechanism of glow starter can be classified into two groups. One is open failure due to glow tube cracking and capacitance changing. The other failure mode is short failure due to contact welding of bimetal in glow tube. In this study, main failure mechanism of glow starter was glow tube cracking due to on/off cycle in accordance with different test conditions of acceleration stresses(voltage).
손영갑,장석원,김재중,Son, Young-Kap,Chang, Seog-Weon,Kim, Jae-Jung 한국마이크로전자및패키징학회 2008 마이크로전자 및 패키징학회지 Vol.15 No.2
본 논문은 블루투스 모듈의 구조 및 솔더접합부에 대한 신뢰성 평가에 국한된 기존의 방법을 확장하여 정량적인 신뢰성 평가를 수행한 결과를 나타낸다. Field 환경조건에서의 정량적인 신뢰성 평가를 위해, 온도 싸이클링(temperature/thermal cycling)에서의 온도차를 가속스트레스로 선정하여 가속수명시험을 실시하였다. 가속수명시험을 통해 구한 고장시간 데이터들을 이용하여 수명분포 매개변수들을 추정하고 코핀-만슨(Coffin-Manson) 모델을 이용하였다. 가속수명시험을 수행한 결과, 블루투스 모듈의 고장모드는 Open, 고장메커니즘은 크랙(Crack)과 박리(Delamination)였다. Field에서 수거한 고장품들의 고장모드와 고장메커니즘이 가속수명시험을 통해 재현되었다. 또한 본 논문에서 블루투스 모듈이 Field에서 받을 수 있는 온도 싸이클링에서의 다양한 온도차에 대한 정량적인 수명을 예측할 수 있는 방법이 제시되었다. 제안된 방법을 이용하여 온도차 $70^{\circ}C$를 받고 있는 블루투스 모듈의 $B_{10}$ 수명은 약 4년으로 추정되었다. This paper shows quantitative reliability evaluations of a Bluetooth module through extending previous qualitative methods limited to structure reliability tests and solder joint reliability tests for Bluetooth modules. Accelerated Life Testing (ALT) of the modules using temperature difference in temperature cycling as an accelerated stress was conducted for quantitative reliability evaluation under field environment conditions. Lifetime distribution parameters were estimated using the failure times obtained through the ALT, and then Coffin-Manson model was implemented. Results of the ALT showed that the failure mode of the modules was open and the failure mechanisms are both crack and delamination. The ALT reproduced the failure mode and mechanisms of failed Bluetooth modules collected from the field. Further, a quantitative reliability evaluation method with respect to various temperature differences in temperature cycling was proposed in this paper. $B_{10}$ lifetime of the module for the temperature difference $70^{\circ}C$ using the proposed method would be estimated as about 4 years.
효율적인 ESD(ElectroStatic Discharge) test를 위한 Stress mode 제안
강지웅(Ji-Ung Gang),장석원(Seog-Weon Chang),곽계달(Kae-Dal Kwack) 대한기계학회 2008 대한기계학회 춘추학술대회 Vol.2008 No.11
Electrostatic discharge(ESD) phenomenon is a serious reliability concern. It causes approximately most of all field failures of IC. To quality the ESD immunity of IC product, there are some test methods and standards developed. ESD events have been classified into 3 models, which are HBM, MM and CDM. All the test methods are designed to evaluate the ESD immunity of IC products. This study provides an overview among ESD test methods on ICs and an efficient ESD stress method. We have estimated on all pin combination about the positive and negative ESD stress. We make out the weakest stress mode. This mode called a worst-case mode. We proposed that positive supply voltage pin and I/O pin combination is efficient because it is a worst-case mode.
슬라이드형 휴대폰 FPCB(Flexible Printed Circuit Board)의 수명예측
최진영(Jin-Young Choi),장석원(Seog-Weon Chang),곽계달(Kae-Dal Kwack) 대한기계학회 2008 대한기계학회 춘추학술대회 Vol.2008 No.11
The FPCB is used as the important component of the sliding mechanism of mobile phones. FPCB have been used as jumper cables(fixed wiring) in various types of circuits because of their flexibility and bending property. The dominant failure mode of the FPCB is open that was caused by fatigue. The fatigue is repeated whenever the sliding is open, so it is a mainly cause of FPCB fatigue. We examined the bending-fatigue lifetime of FPCB. we focused on observing the contact resistance degradation of FPCB of mobile phones according to different test condition of bending strain. As a result, it has proved that lifetime decreased by increasing bending strain.
김재중(Jae Jung Kim),장석원(Seog Weon Chang),손영갑(Young Kap Son) 대한기계학회 2008 大韓機械學會論文集A Vol.32 No.5
This paper proposes a way to predict electrical lifetime of a relay using Accelerated Life Testings (ALTs). The relay of interest mounting on printed circuit boards is usually under an inrush current stress. The inrush current is generated and accelerated through controlling a lamp switching device in the ALT. We find that the dominant failure mechanism under high levels of inrush current would be contact welding in the contact surface of the relay and the contact welding process is accelerated according to increase in inrush current. The electrical lifetime model based on Inverse Power Law in term of inrush current is proposed, and parameters characterizing relay’s lifetime distribution are statistically estimated using ALTA 6 PRO software.
Rib의 형상에 따른 PDP용 Heat Spreader의 냉각성능 향상
김재중(Jae-Jung Kim),이창희(Chang-Hee Lee),신승훈(Seung-hoon Shin),장석원(Seog-Weon Chang) 대한기계학회 2001 대한기계학회 춘추학술대회 Vol.2001 No.9
This paper reports a result of numerical analysis on the heat transfer enhancement of ribbed PDP heat spreader. Three different ribs are compared in this study. In general, the heat transfer on a vertical plate is enhanced when a rib is attached as the surface area increased and the growth of the boundary layer is interrupted. Cooling performance is evaluated with temperature uniformity and dimensionless temperature difference between surface temperature of heat spreader and ambient temperature. Among the three ribs, V-shaped one showed the best performance.
안재욱(Jae-Uk An),김재중(Jae-Jung Kim),장석원(Seog-Weon Chang),곽계달(Kae-Dal Kwack) 대한기계학회 2006 대한기계학회 춘추학술대회 Vol.2006 No.11
This study presents predicting electrical life of relay which is mounting in PCB by the reliability tool ALT. In ALT, we have focused on observing the change of contact surface of relay according to the inrush current level which is generated by lamp switching. Observing contact surface, it has proved that dominant failure mechanism on the contact surface under strong inrush current are material transfer, erosion and contact welding. Additionally we have obtained that life of relay under 70A, Inrush Current, is 237,526 cycles from the results of ALTA software.