• Title/Summary/Keyword: mechanical shock reliability

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Lead-free Solder for Automotive Electronics and Reliability Evaluation of Solder Joint (자동차 전장용 무연솔더 및 솔더 접합부의 신뢰성 평가)

  • Bang, Jung-Hwan;Yu, Dong-Yurl;Ko, Young-Ho;Yoon, Jeong-Won;Lee, Chang-Woo
    • Journal of Welding and Joining
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    • v.34 no.1
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    • pp.26-34
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    • 2016
  • Automotive today has been transforming to an electronic product by adopting a lot of convenience and safety features, suggesting that joining materials and their mechanical reliabilities are getting more important. In this study, a Sn-Cu-Cr-Ca solder composition having a high melting temperature ($>230^{\circ}C$) was fabricated and its joint properties and reliability was investigated with an aim to evaluate the suitability as a joining material for electronics of engine room. Furthermore, mechanical properties change under complex environment were compared with several existing solder compositions. As a result of contact angle measurement, favorable spreadability of 84% was shown and the average shear strength manufactured with corresponding composition solder paste was $1.9kg/mm^2$. Also, thermo-mechanical reliability by thermal shock and vibration test was compared with that of the representative high temperature solder materials such as Sn-3.5Ag, Sn-0.7Cu, and Sn-5.0Sb. In order to fabricate the test module, solder balls were made in joints with ENIG-finished BGA and then the BGA chip was reflowed on the OPS-finished PCB pattern. During the environmental tests, resistance change was continuously monitored and the joint strength was examined after tests. Sn-3.5Ag alloy exhibited the biggest degradation rate in resistance and shear stress and Sn-0.7Cu resulted in a relatively stable reliability against thermo-mechanical stress coming from thermal shock and vibration.

Shock Analysis of Mobile Power Supply Container for Radar with MIL-STD-810H (MIL-STD-810H를 적용한 레이더 전력공급용 이동식 컨테이너의 충격해석)

  • Kwon, Jaeeon;Shin, Dongwon;Hur, Jangwook
    • Journal of the Korea Institute of Military Science and Technology
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    • v.24 no.6
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    • pp.569-576
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    • 2021
  • Radar is a ground defense system that detects enemy aircraft and receives power from a mobile power supply in an emergency. Serious problems may occur if the equipment is damaged by impact during transportation for use. The US military standard MIL-STD-810H contains information on environmental tests such as shock and vibration applied to munitions. Therefore, in this study, the transient analysis of ANSYS 19.2 was performed using the impact data specified in MIL-STD-810H as an input value. Through this, the maximum stress generated in the impact environment of the mobile power supply container was derived, and the safety margin was calculated to confirm the reliability of the container.

Shock-Absorbing Safety Mechanism Based on Transmission Angle of a 4-Bar Linkage (4절링크의 전달각에 기초한 충격흡수식 안전기구)

  • Park, Jung-Jun;Kim, Byeong-Sang;Song, Jae-Bok
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.29 no.11 s.242
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    • pp.1534-1541
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    • 2005
  • Unlike industrial manipulators, the manipulators mounted on service robots are interacting with humans in various aspects. Therefore, safety has been one of the most important design issues. Many compliant robot arms have been introduced for safety. It is known that passive compliance method has faster response and higher reliability than active ones. In this paper, a new safety mechanism based on passive compliance is proposed. Passive mechanical elements, specifically transmission angle of the 4-bar linkage, springs and shock absorbing modules are incorporated into this safety mechanism. This mechanism works only when the robot arm exerts contact force much more than the human pain tolerance. Validity of this mechanism is verified by simulations and experiments. It is shown that the manipulator using this mechanism provides higher performance and safety than those using other passive compliance mechanisms or active methods.

Performance evaluation on the separation device activated by shape memory alloy actuator (형상기억합금을 이용한 소형 위성용 분리장치의 성능평가)

  • Choi, Junwoo;Lee, Dongkyu;Hwang, Kukha;Lee, Minhyung;Kim, Byungkyu
    • Journal of the Korean Society for Aeronautical & Space Sciences
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    • v.43 no.7
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    • pp.635-640
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    • 2015
  • In this paper, we report a non-explosive separation device for a small satellite which utilize a shape memory alloy actuator. Based on previous research, we try to increase the reliability of the proposed device by changing some components. It enables the proposed device to activate under high preload. Also, we confirm it generates low shock which is main advantage of non-explosive separation device. Finally, vibration test which mimics launching environment and thermal vacuum test which mimics space environment are carried out respectively. After each environment test, we confirm the proposed device is successfully activated. Conclusively, we develop a non-explosive separation device which can activate with low shock under high preload after shock and environment tests(vibration and thermal vacuum tests).

Study on Joint of Micro Solder Bump for Application of Flexible Electronics (플렉시블 전자기기 응용을 위한 미세 솔더 범프 접합부에 관한 연구)

  • Ko, Yong-Ho;Kim, Min-Su;Kim, Taek-Soo;Bang, Jung-Hwan;Lee, Chang-Woo
    • Journal of Welding and Joining
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    • v.31 no.3
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    • pp.4-10
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    • 2013
  • In electronic industry, the trend of future electronics will be flexible, bendable, wearable electronics. Until now, there is few study on bonding technology and reliability of bonding joint between chip with micro solder bump and flexible substrate. In this study, we investigated joint properties of Si chip with eutectic Sn-58Bi solder bump on Cu pillar bump bonded on flexible substrate finished with ENIG by flip chip process. After flip chip bonding, we observed microstructure of bump joint by SEM and then evaluated properties of bump joint by die shear test, thermal shock test, and bending test. After thermal shock test, we observed that crack initiated between $Cu_6Sn_5IMC$ and Sn-Bi solder and then propagated within Sn-Bi solder and/or interface between IMC and solder. On the other hands, We observed that fracture propated at interface between Ni3Sn4 IMC and solder and/or in solder matrix after bending test.

A Research on the reappearance of delamination and the characteristic of LED package by thermal shock test (열충격 시험을 통한 LED Package의 박리재현 및 특성에 관한 연구)

  • Jang, In-Hyeok;Lim, Houng-Woo
    • Journal of Applied Reliability
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    • v.13 no.3
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    • pp.207-216
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    • 2013
  • This paper, we classified LED failure mechanisms that occur due to the delamination and analyzed each of the mechanism that gives the LED PKGs the effect. Usually, the LED is composed of several materials which are LED chips, gold wire, phosphor, epoxy resin, adhesive, reflector and lead frame. These different materials are usually delaminated in trouble conditions which are huge temperature difference, hot and humid or mechanical shocked. When the components are delaminated, a luminance will be lost and moisture be absorbed easily, a thermal resistance be increased attendantly. In this paper, we experimented to investigate failure mechanism of the thermal resistance and failure mechanism of the decrease of luminance that occur due to the delamination. A thermal shock test was performed to reproduce this phenomena by subjecting samples to a cold-hot cyclling process between $-30^{\circ}C$(15min) and $110^{\circ}C$(15min). The samples were inspected at 200, 600 and 1,000 cycles. We measured feature of LED using the spatial analyzer, optical microscope, thermal resistance, photometer, scanning electron microscope (SEM). As a result, the progression of the crack and the thermal resistance and decrease in luminance are proportional to number of thermal shock.

Fluidic Thrust Vector Control Using Shock Wave Concept (충격파 개념에 기반한 유체 추력벡터제어에 관한 연구)

  • Wu, Kexin;Kim, Heuy Dong
    • Journal of the Korean Society of Propulsion Engineers
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    • v.23 no.4
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    • pp.10-20
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    • 2019
  • Recently, fluidic thrust vector control has become a core technique to control multifarious air vehicles, such as supersonic aircraft and modern rockets. Fluidic thrust vector control using the shock vector concept has many advantages for achieving great vectoring performance, such as fast vectoring response, simple structure, and low weight. In this paper, computational fluid dynamics methods are used to study a three-dimensional rectangular supersonic nozzle with a slot injector. To evaluate the reliability and stability of computational methodology, the numerical results were validated with experimental data. The pressure distributions along the upper and lower nozzle walls in the symmetry plane showed an excellent match with the test results. Several numerical simulations were performed based on the shear stress transport(SST) $k-{\omega}$ turbulence model. The effect of the momentum flux ratio was investigated thoroughly, and the performance variations have been clearly illustrated.

Reliability and utility of a Dry Test Bench for testing the acoustic output from a ballistic shock wave therapeutic device (탄도형 충격파 치료기의 음향 출력 시험을 위한 Dry Test Bench의 신뢰성 및 유용성)

  • Jeon, Sung Joung;Lee, Min Young;Kwon, Oh Bin;Kim, Jong Min;Choi, Min Joo
    • The Journal of the Acoustical Society of Korea
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    • v.41 no.5
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    • pp.589-600
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    • 2022
  • In order to verify the reliability of Dry Test Bench (DTB) used for testing the output energy from ballistic extracorporeal shock wave therapeutic devices, the measurements with DTB were compared with the acoustic energy measured with a Laser Doppler Vibrometer (LDV) for a commercial ballistic ESWT device. It was shown that the mechanical energy detected with DTB had variability maintained within 5 % at the same output power setting and also had a linear correlation (adj. R2 = 0.991) with the acoustic energy measured with the LDV for the entire output power settings. Using the correlation between the two methods and the correlation on the acoustic energy measured in between air and water with the LDV, the DTB measurement can be used to estimate the energy flux density in water with an average error of 7.85 % for the entire output power settings of the ballistic shock wave generator considered in the experiment. DTB provides information limited to the output mechanical energy and therefore it is not suitable for testing the various acoustic output parameters required in IEC61846 and IEC63045. However, DTB that is simple in measurement principles and easy to use is expected for manufacturers and clinical users to monitor the performance of ballistic Extracorporeal Shock Wave Therapy (ESWT) devices.

The Reliability of Optical Fiber Assembly Using Glass Solder

  • Lee, Jong-Jing;Kang, Hyun-Seo;Koh, Jai-Sang
    • Proceedings of the Korean Reliability Society Conference
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    • 2004.07a
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    • pp.147-151
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    • 2004
  • In this study, an optical fiber assembly directly coupled with a laser diode or a photo diode is designed to confirm high reliable optical coupling efficiency of optical transmitter(Tx) and receiver(Rx). The optical fiber assembly is fabricated by soldering an optical fiber and a Kovar ferrule using a glass solder after inserting an optical fiber through a Kovar ferrule. The Kovar which has good welding characteristics is applied to introduce laser welding technique. The glass solder has excellent thermal characteristics such as thermal shift delamination compared with PbSn, AuSn solder previously used usually. Furthermore, the glass solder doesn't need fiber metalization and this enables low cost fabrication. However, the glass soldering is high temperature process over 35$0^{\circ}C$ and the convex shape after solidification due to surface tension causes the stress concentration on optical fiber. The stress concentration on the optical fiber increases the optical insertion loss and possibility of crack formation. The shape of glass solder was designed referring to 2-D Axi-symmetric FEM simulation. To test the mechanical reliability, mechanical vibration test and shock test were done according to Telcorida GR-468-Core protocol. After each test, the optical loss of the stress distributed fiber assembly didn't exceed 0.5 dB, which passes the test.

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Thermo-mechanical reliability evaluation of flip chip package using a accelerated test (가속화 시험을 통한 플립칩 패키지의 열적 기계적 특성 평가)

  • Kim Dae-Gon;Ha Sang-Su;Kim Jong-Ung;Sin Yeong-Ui;Jeong Seung-Bu
    • Proceedings of the KWS Conference
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    • 2006.05a
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    • pp.21-23
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    • 2006
  • The microstructural investigation and thermo-mechanical reliability evaluation of the Sn-3.0Ag-0.5Cu solder bumped flip chip package were carried out during the thermal shock test of the package. In the initial reaction, the reaction product between the solder and Cu mini bump of chip side was Cu6Sn5 layer, while the two phases which were (Cu,Ni)6Sn5 and (Ni,Cu)3Sn4 were formed between the solder and Ni-P layer of the package side. The cracks were occurred at the corner solder joints after the thermal shocks of 400 cycles. The primary failure mechanism of the solder joints in this type of package was confirmed to be thermally activated solder fatigue failure.

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