• Title/Summary/Keyword: 온도싸이클 시험

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A Study on the Assembly Process and Reliability of COF (Chip-On-Flex) Using ACFs (Anisotropic Conductive Films) for CCM (Compact Camera Module) (ACF를 이용한 CCM (Compact Camera Module)용 COF(Chip-On-Flex) 실장 기술 및 신뢰성 연구)

  • Chung, Chang-Kyu;Paik, Kyung-Wook
    • Journal of the Microelectronics and Packaging Society
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    • v.15 no.2
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    • pp.7-15
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    • 2008
  • In this paper, the Chip-On-Flex (COF) assembly process using anisotropic conductive films (ACFs) was investigated and the reliability of COF assemblies using ACFs was evaluated. Thermo-mechanical properties of ACFs such as coefficient of thermal expansion (CTE), storage modulus (E'), and glass transition temperature $(T_g)$ were measured to investigate the effects of ACF material properties on the reliability of COF assemblies using ACFs. In addition, the bonding conditions for COF assemblies using ACFs such as time, temperature, and pressure were optimized. After the COF assemblies using ACFs were fabricated with optimized bonding conditions, reliability tests were then carried out. According to the reliability test results, COF assemblies using the ACF which had lower CTE and higher $T_g$ showed better thermal cycling reliability. Consequently, thermo-mechanical properties of ACFs, especially $T_g$, should be improved for high thermal cycling reliability of COF assemblies using ACFs for compact camera module (CCM) applications.

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A Study of Two-Mode Failure Model for Crystalline Si Photovoltaic Module (실리콘 태양전지 모듈의 two-mode failure 모델의 연구)

  • Choi, Ki Young;Oh, Won Wook;Kang, Byung Jun;Kim, Young Do;Tark, Sung Ju;Kim, Donghwan
    • 한국신재생에너지학회:학술대회논문집
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    • 2011.11a
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    • pp.62.2-62.2
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    • 2011
  • To guarantee 20-25 years to the lifetime of the PV modules without failure, reliability test of the module is very important. Field-aged test of the outdoor environment is required. However, due to time constraints, accelerated testing is required to predict the lifetime of PV modules and find causes of failure. Failure is caused by many complex phenomena. In this study, we experimented two accelerated tests about corrosion and fatigue, respectively. First, temperature cycling test for fatigue were tested and Coffin-Manson equation was analyzed. Second, damp heat test for corrosion were tested and Eyring equation were analyzed. Finally, using two-mode failure model, we suggest a new lifetime model that analyze the phenomenon by combining two kinds of data.

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Effect of Low Temperature and Single Overload on Fatigue Crack Growth Behavior of Cr-Mo Steel Weldments (Cr-Mo강 용접부의 피로균열 성장거동에 미치는 저온도와 단일과대하중의 영향)

  • Lim, Jae Kyoo
    • Journal of Welding and Joining
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    • v.14 no.2
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    • pp.79-89
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    • 1996
  • 일정진폭하중과 과대하중비 2.5의 단일 인장과대하중에 의한 4140강 용접부 의 피로균열성장거동을 실온과 -45.deg.C의 저온에서 피로시험과 파면관찰을 통하여 고찰하였다. 이때, 용접부 미시조직의 영향을 평가하기 위해 모재(parent metal), 열영향부(as-welded HAZ), 열처리된 열영향부(PWHT HAZ)로 나누어 응력비 0과 0.5로 CT시험편을 이용하여 피로시험을 실시하였다. 피로균열성장거동은 재료의 미시조직과 온도변화보다는 응력비에 크게 영향을 받았으며, 단일 과대하중에 의한 피로균열성장 지연효과가 모든 재료에서 상당히 크게 나타났다. 전자현미경에 의한 피로파면 관찰 결과, 실온에서는 연성의 스트라이에이숀과 -45.deg.C에서는 의벽개파면과 같은 피로 균열성장거동을 나타내고 있다.

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온도분포가 이동하는 액체금속로 원통용기의 열적 라체팅 해석

  • Lee, Hyeong-Yeon;Kim, Jong-Beom;Lee, Jae-Han;Koo, Kyung-Hoe;Yoo, Bong;Gwak, Dae-Yeong;Im, Yong-Taek
    • Proceedings of the Korean Nuclear Society Conference
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    • 1996.05d
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    • pp.235-240
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    • 1996
  • 본 연구에서는 고온의 천이 열하중을 받는 304 SS 재질의 액체금속로 원통용기에 대하여 진행성 변형기구인 열적 라체팅(thermal ratcheting) 변형거동을 해석하였다. 재료의 반복 소성을 나타내는 구성식으로서 Chaboche모델을 이용하였으며 이 모델의 적용을 위하여 ABAQUS의 사용자 프로그램을 개발하였다. 열천이 과정이 반복되는 동안에 축방향의 온도분포 이동에 따른 탄소성 해석을 수행한 결과 소성변형이 각 싸이클마다 누적되어 점진적 변형이 일어났으며 이 해석결과를 시험치와 비교함으로써 해석의 타당성을 검토하였다. 반복 소성거동에 대한 Chaboche 모델을 이용하면 천이 열하중을 받는 304 SS. 재질의 고온구조물에 대하여 라체팅 거동을 정량적으로 평가 할 수 있는 것으로 나타났다.

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Thermal/Mechanical Properties of Hafnium Carbide Coatings on Carbon-Carbon Composites (탄소-탄소 복합재료의 하프늄 탄화물 코팅재의 열적/기계적 특성)

  • Choi, So-dam;Seo, Hyoung-IL;Lim, Byung-Joo;Sihn, Ihn Cheol;Lee, Jung Min;Park, Jong Kyoo;Lee, Kee Sung
    • Composites Research
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    • v.31 no.5
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    • pp.260-266
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    • 2018
  • This study investigates thermal and mechanical characterization of Hafnium carbide coating on the $C_f-C$ composites. The hafnium carbide coatings by vacuum plasma spray on the C/C-SiC composites are prepared to evaluate oxidation and wear resistance. We perform the thermal durability tests by thermal cycling at $1200^{\circ}C$ for 10cycles in air and investigates the weight change of each cycle. We also evaluate the wear and indentation behavior using tungsten carbide ball indenter as a mechanical evaluation. As a result, the HfC coating is beneficial to reduce of weight loss during thermal cycling test and improve the elastic property of C/C-SiC composite. Especially, the HfC coating improves the wear resistance of C/C-SiC composite.

Computer Simulation of Solidification Process in the Gravity Die Casting of Cast Iron (주철의 중력금형주조에서 응고과정의 컴퓨터해석)

  • Choi, Jeong-Kil;Hong, Chun-Pyo
    • Journal of Korea Foundry Society
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    • v.10 no.3
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    • pp.247-253
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    • 1990
  • 주철의 중력금형주조에서 반복작업에 따른 응고과정의 변화를 3차원의 수치해석적 방법에 의하여 컴퓨터해석을 하였다. 수치해석적 방법으로는 차분법을 채택하였다. 반복작업과정에 따라 변화되어지는 주물의 응고시간과 미세조직, 기계적성질과의 관계가 조사 되어졌다. 컴퓨터에 의해 계산된 각싸이클의 냉각속도로 부터 주물의 공정셀의 수, 경도, 인장강도등의 변화를 예측하였으며 또한 반복싸이클에 따른 금형 및 주물의 온도분포와 최종응고부위등을 예측하였고 이들은 실제주조시험에서 얻어진 결과와 비교적 잘일치하였다. 중력금형주조에서 회주철의 응고시간, 공정셀, 기계적성질 및 응고속도에 미치는 냉각수의 영향이 또한 컴퓨터해석에 의하여 잘예측되었으며 컴퓨터해석에 의한 냉각수 라인의 적절한 설계에 의하여 주물의 미세조직 및 기계적성질과 결함발생 가능위치를 효과적으로 제어할수 있음을 확인하였다.

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Characteristics of Reliability for Flip Chip Package with Non-conductive paste (비전도성 접착제가 사용된 플립칩 패키지의 신뢰성에 관한 연구)

  • Noh, Bo-In;Lee, Jong-Bum;Won, Sung-Ho;Jung, Seung-Boo
    • Journal of the Microelectronics and Packaging Society
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    • v.14 no.4
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    • pp.9-14
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    • 2007
  • In this study, the thermal reliability on flip chip package with non-conductive pastes (NCPs) was evaluated under accelerated conditions. As the number of thermal shock cycle and the dwell time of temperature and humidity condition increased, the electrical resistance of the flip chip package with NCPs increased. These phenomenon was occurred by the crack between Au bump and Au bump and the delamination between chip or substrate and NCPs during the thermal shock and temperature and humidity tests. And the variation of electrical resistance during temperature and humidity test was larger than that during thermal shock test. Therefore it was identified that the flip chip package with NCPs was sensitive to environment with moisture.

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Thermal and Mechanical Evaluation of Environmental Barrier Coatings for SiCf-SiC Composites (SiCf-SiC 복합재료의 내환경 코팅 및 열, 기계적 내구성 평가)

  • Chae, Yeon-Hwa;Moon, Heung Soo;Kim, Seyoung;Woo, Sang Kuk;Park, Ji-Yeon;Lee, Kee Sung
    • Composites Research
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    • v.30 no.2
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    • pp.84-93
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    • 2017
  • This study investigates thermal and mechanical characterization of environmental barrier coating on the $SiC_f-SiC$ composites. The spherical environmental barrier coating (EBC) powders are prepared using a spray drying process for flowing easily during coating process. The powders consisting of mullite and 12 wt% of Ytterbium silicate are air plasma sprayed on the Si bondcoat on the LSI SiC fiber reinforced SiC composite substrate for protecting the composites from oxidation and water vapor reaction. We vary the process parameter of spray distance during air plasma spray of powders, 100, 120 and 140 mm. After that, we performed the thermal durability tests by thermal annealing test at $1100^{\circ}C$ for 100hr and thermal shock test from $1200^{\circ}C$ for 3000 cycles. As a result, the interface delamination of EBC never occur during thermal durability tests while stable cracks are prominent on the coating layer. The crack density and crack length depend on the spray distance during coating. The post indentation test indicates thermal tests influence on the indentation load-displacement mechanical behavior.

Electrochemical Characteristics of an Electric Double Layer Supercapacitor Electrode using Cooked-Rice based Activated Carbon (쌀밥으로 제조된 활성탄을 사용하는 전기이중층형 슈퍼커패시터 전극의 전기화학적 특성)

  • Jo, Un;Kim, Yong-Il;Yoon, Jae-Kook;Yoo, Jung-Joon;Yoon, Ha-Na;Kim, Sung-Soo;Kim, Jong-Huy
    • Journal of the Korean Electrochemical Society
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    • v.16 no.3
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    • pp.129-137
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    • 2013
  • From the cooked-rice as a raw material, activated carbons throughout a hydrothermal synthesis and vacuum soak of KOH for chemical activation were obtained. Activated carbon electrodes for electric double layer supercapacitors were prepared and electrochemical characteristics were examined. Including the specific surface area by BET method and pore size distribution by NLDFT method, physical properties of activated carbons were investigated by means of SEM, EDS, XRD, and TG analyses. Cycle voltammetry and AC-impedance measurements were conducted to confirm the electrochemical characteristics for the electrodes. From hydrothermal synthesis, $5{\sim}7{\mu}m$ diameters of spherical carbons were obtained. After the activation at $800^{\circ}C$, it was notable for the activated carbon to be the specific surface $1631.8cm^2/g$, pore size distribution in 0.9~2.1 nm, and micro-pore volume $0.6154cm^3/g$. As electrochemical characteristics of the activated carbon electrode in 6M KOH electrolyte, it was confirmed that the specific capacitances of 236, 194, and 137 F/g at the scan rate of 5, 100, and 500 mV/s respectively were exhibited and 91.2% of initial capacitance after 100,000 cycles at 200 mV/s was maintained.

An Experimental Study on the Freeze-Thaw Resistance of Concrete Incorporating Waste Foundry Sand (폐주물사를 혼입한 콘크리트의 동결-융해 저항성에 관한 실험적 연구)

  • 윤경구;이주형;홍창우;박제선
    • Magazine of the Korea Concrete Institute
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    • v.10 no.4
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    • pp.153-161
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    • 1998
  • Concrete structures has been deteriorated by and freezing the thawing due to temperature gap. This study was conducted to evaluate durability of concrete which are increasingly demanded recently. Therefore the research of durability must be executed for application of waste foundry sand concrete real structures. Concrete durability properties incorporating waste foundry sand was performed with the variable of W/C ratio. Sand/Waste foundry sand ratio and Air entrainment-Non air entrainment. Cylinder specimens were made and subjected to freezing and thawing cycle at -18$^{\circ}C$ and 4$^{\circ}C$. Dynamic modulus of elasticity were evaluated as F/T cycle increase. The results show that strength of concrete is increased the W/C ratio decrease, the Sand/Waste foundry sand ratio increases when the concrete contains AE agent and decreasing W/C ratio and AE concrete makes improved resistance of freezing and thawing improved. Especially, resistance of freezing and thawing is improved by Fine aggregate/Waste foundry sand ratio which is 50%, 25%, 0% in a row. Therefore it is turn out the waste foundry sand could be applied to concrete from the experiment.