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MIL-STD-810 환경시험조건을 이용한 무기체계 핵심구성품 온도/진동복합 정상수명시험 설계 방안
강태엽(Tae Yeob Kang),서동환(Donghwan Seo),민준기(Joonki Min),이강영(Kangyoung Lee),김성규(Sungkyu Kim),홍정표(Jeongpyo Hong),양일영(Ilyoung Yang),유상우(Sangwoo Yu) 한국신뢰성학회 2021 신뢰성응용연구 Vol.21 No.1
Purpose: Previous work regarding reliability testing has focused on accelerated life testing, leading to a lack of information on non-accelerated life testing; however, it is a proper choice when testing time is not a constraint. Methods: Therefore, the design process of the non-accelerated testing is proposed, including selecting the essential component to test, defining target life expectancy and main stress factors, designing testing profiles, and determining the number of test items and testing periods. Especially, this paper provides the guideline with which the stress levels and the test profile can be designed based on the MIL-STD-810 standard. Results: We show that the vibration testing profile can be designed by applying the Miner-Palmgren rule to the given MIL-STD-810 profile. The temperature range of interest was directly derived from the standard. Conclusion: This paper presents the design guideline of the non-accelerated life testing case where the test item is an essential component of defense systems and the main stress factors are temperature and vibration.
Reliability assessment on electrical interconnects by using resonance in the high frequency regime
Tae Yeob Kang(강태엽),Joonki Min(민준기),Donghwan Seo(서동환),Taek-Soo Kim(김택수) 대한기계학회 2021 대한기계학회 춘추학술대회 Vol.2021 No.4
Recently, there has been growing interest in monitoring the ongoing health of products and systems in order to predict component failures in advance of the catastrophic one. Even though PHM technologies have been well developed regarding solder-joint interconnections, in-depth studies on the failure initiation signals from bond wire interconnects are needed. In this paper, we address the technical issues of bond wire interconnects on the high frequency performance and failure initiation under severe temperature environments. We paid attention to the certain scattering parameter(S-parameter) patterns of each defective interconnect to provide information about both the severity of defects and the causes. S-parameters describe the electrical behavior of electrical networks when undergoing various steady state stimuli by electrical signals. Many electrical properties of networks of components (inductors, capacitors, resistors) may be expressed using S-parameters. Also, the S-parameter measurements using network analyzers are the most basic work of RF engineering. One of the basic tools in the RF design process is the use of S-parameter measurements. These measurements can be used in today’s computer-aided design (CAD) tools as part of the circuit-simulation process. S-parameters describe a component as a black box and are used to emulate behavior of electronic components over a range of frequencies. Thus, it would be highly convenient if the defects could be detected and analyzed by the s-parameter measurement itself. Therefore, it would be convenient if performance variation and crack initiation would be shown with the s-parameter alone. In this study, we show the performance variation of bond wire interconnects with S parameter supported by the impedance modeling. The model is verified by ADS simulation. Also, it is suggested that insertion loss can be a useful prognostics factor. This paper provides mechanical and electrical understanding of the behaviors of bond wire interconnects under thermal cyclings. The resonance movement with the crack propagation is compared to DC resistance measurement results. As shown in Figure 1, while the resonance peaks move several hundred MHz as the thermal cycle increases, the DC resistance doesn’t change. Even right before the failure, DC resistance doesn’t show any precursor. However, the resonance frequency depicts the changes caused by the beginning, development and the end of the failure. Even though many researchers have suggested serial ohmic resistance measurements, joint time-frequency domain reflectometry and S-parameters as PHM tools for interconnects such as solder joints and a through-silicon via(TSV), we suggest the resonance frequency as an effective failure indication for bond wire interconnects. The aforementioned resonance movement with the crack propagation is compared to DC resistance measurement results with the 10 mm wire case. While the resonance peaks move several hundred MHz as the thermal cycle increases, the DC resistance doesn’t change. Even right before the failure, DC resistance doesn’t show any precursor. However, the resonance frequency depicts the changes caused by the beginning, development and the end of the failure. Even though many researchers have suggested serial ohmic resistance measurements, joint time-frequency domain reflectometry and S-parameters as PHM tools for interconnects such as solder joints and a through-silicon via(TSV), we suggest the resonance frequency as an effective failure indication for bond wire interconnects. Experimental results show scanning electron microscope(SEM) images of the bond wire specimen after the failure which occurred at the neck. The bond wire loop did not remain the original shape after the break because of the remaining stress in the wire. The bonding area was left on the pad.
균열에 대한 전기적 모델과 S-파라미터 패턴을 이용한 솔더조인트 신뢰성 분석
최병철(Byeongcheol Choe),강태엽(Tae Yeob Kang) 한국신뢰성학회 2023 신뢰성응용연구 Vol.23 No.1
Purpose: Electrical interconnects affect the reliability and performance of entire electronic systems - especially as operating frequencies and clock speeds in processors are increasing annually. We suggest the S-parameter pattern analysis method is used to evaluate the reliability of the commonly-used solder-joint interconnect. Method: An impedance model of the solder-joint interconnect was developed to study the effect of crack evolution. Simulation Program with Integrated Circuit Emphasis (SPICE) simulations, using a suggested impedance model, were then performed and the crack evolution was tracked using the S-parameter pattern analysis. Results: In the crack initiation phase, a resonance peak occurred on the S-parameter pattern and it the peak moved toward lower frequencies as the crack propagated until failure. Conclusion: This study demonstrated that monitoring the resonant frequency in the S-parameter pattern can predict the initiation and evolution of cracks in the solder-joint interconnects.
S-parameter의 변화를 유도하는 임피던스 변화 감지를 통한 전자회로의 결함검출회로
서동환(Donghwan Seo),강태엽(Tae-yeob Kang),유진호(Jinho Yoo),민준기(Joonki Min),박창근(Changkun Park) 한국전기전자학회 2021 전기전자학회논문지 Vol.25 No.4
본 논문에서는 고장예측진단 및 건전성 관리 기법(Prognostics and Health Management, PHM)을 적용하기 위해 해당 시스템 혹은 회로 내부에서 결함특성을 감지하고 예측할 수 있는 회로 구조를 제안하였다. 기존 연구에서 회로 결함의 진행에 따라, S-parameter 크기 최소값의 주파수가 변화하는 것을 확인하였다. 이러한 특성을 기존에는 네트워크 분석기(Network Analyzer)를 활용하여 측정하였으나, 본 연구에서는 같은 결함검출기법을 활용하더라도 큰 계측장비 없이 결함의 진행상황 및 잔여 수명, 결함발생 여부를 확인할 수 있는 소형화된 회로를 설계하였다. 본 연구에서는 S-parameter의 변화를 야기하는 임피던스의 변화를 감지할 수 있도록 회로를 설계하였으며, Bond-wire의 온도반복에 따른 S-parameter 변화 측정결과를 제안하는 회로에 적용하였다. 이를 통해 해당 회로가 Bond-wire의 결함을 감지할 수 있다는 것을 성공적으로 검증하였다. In this paper, in order to apply Prognostics and Health Management(PHM) to an electronic system or circuit, a circuit capable of detecting and predicting defect characteristics inside the system or circuit is implemented, and the results are described. In the previous study, we demonstrated that the frequency of the amplitude of S-parameter changed as the circuit defect progressed. These characteristics were measured by network analyser. but in this study, even if the same defect detection method is used, a circuit is proposed to check the progress of the defect, the remaining time, and the occurrence of the defect without large measurement devices. The circuit is designed to detect the change in impedance that generates changes of S-parameter, and it is verified through simulation using the measurement results of Bond-wires.