• Title, Summary, Keyword: 굽힘 저항

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Bending Characteristics of Ag Micro Circuits using Electrohydrodynamics Printing Technology (전기수력학적 프린팅 기술을 이용한 Ag 미세회로의 굽힘 특성)

  • Lee, Yong-Chan;Ahn, Ju-Hun;Lee, Chang-Yull
    • Journal of Aerospace System Engineering
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    • v.13 no.4
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    • pp.37-42
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    • 2019
  • The objective of this study was to study the bending characteristics of Ag nano ink using EHD (Electrohydrodynamics) inkjet printing technology for flexibility and miniaturization of devices. The optimal conditions for the technology were derived, and bending characteristics of the Ag nano circuit obtained. For the EHD printing, it is essential to find the optimal point for each parameter such as material characteristics, density, flow rate, voltage, discharge height etc. Therefore, it was derived as the point from the working height and the applied voltage. Also, bending characteristics are confirmed by measuring resistance with each radius of curvature using a fabricated bending module. It was confirmed that rate of resistance change increases rapidly as the radius of curvature increases.

플라스틱 기판상에 저온 증착된 IZO박막의 특성 연구

  • Jeong, Jae-Hye;Jeong, Yu-Jeong;Yun, Jeong-Heum;Lee, Seong-Hun;Lee, Geon-Hwan
    • Proceedings of the Korean Vacuum Society Conference
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    • pp.455-455
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    • 2010
  • 차세대 디스플레이로 널리 알려져 있는 플렉서블 디스플레이는 휴대하기 쉽고, 깨지지 않으며, 변형이 자유로워 현재 우리 사회에 크게 주목받고 있다. 플렉서블 디스플레이의 구현을 위해서는 기존의 유리 기반 디스플레이 소자 기술에 더하여 플렉서블 기판소재에 적용 가능한 투명전도막 기술의 확립이 필요하다. 디스플레이 산업에서 주로 사용되는 투명전도막은 ITO (indium tin oxide) 및 IZO (indium zinc oxide)와 같은 투명전도성 산화물 박막 (TCO, transparent conducting oxide)이다. 그런데 플라스틱 기판이 굽힘 환경에 놓이게 되면 그 위에 증착된 산화물 박막이 쉽게 파손될 수 있다. 따라서 플렉서블 디스플레이 기술에 있어서 변형에 따른 TCO 박막의 파괴 거동에 대한 연구가 필수적이다. 본 연구에서는 PET (polyethylene terephthalate) 기판 상에 증착된 IZO 박막의 반복 굽힘 시 계면구조 변화에 따른 파괴거동을 조사하였다. 플라스틱 기판의 사용을 위해서는 산소 및 수분의 투과 방지막이 필요하며 본 연구에서는 투과 방지막 (또는 보호막)으로서 $SiO_x$ 박막을 적용하였다. IZO 박막은 $In_2O_3$ - 10 wt% ZnO 타겟을 사용하여 RF magnetron sputtering법으로 $100^{\circ}C$ 미만에서 저온 증착하였다. 보호막으로 사용되는 $SiO_x$ 박막은 HMDSO (hexamethyldisiloxane)와 Ar 및 $O_2$ 혼합기체를 이용하는 PECVD 방법으로 합성하였다. 변형에 따른 TCO 박막의 파괴 거동을 조사하기 위하여 반복 굽힘 시험 (cyclic- bending test)을 실시하였다. 반복 굽힘 시험 중 실시간으로 IZO 박막의 전기저항 변화를 측정하여 박막의 파괴 거동을 모니터링 하였다. 시편 A (135 nm-thick IZO/PET), B (135 nm-thick IZO/ 90 nm-thick $SiO_x$/PET), C (135nm-thick IZO/ 300 nm-thick $SiO_x$/PET)에 대하여 곡지름 35mm, 1000회 반복 굽힘을 실시하여 변형 중의 전기저항 변화를 조사하였다. 그리고 굽힘 시험 완료 후, FE-SEM을 이용한 시편 표면형상 관찰을 통하여 균열생성 정도를 관찰하였다. 반복 굽힘 시험 결과, A 와 C 시편의 경우, 각각 반복 굽힘 20회, 550회에서 급격한 전기저항의 증가가 관찰되었다. 그러나 B 시편의 경우, 1000회 반복 굽힘 후에도 전기저항의 변화는 나타나지 않았다. 이와 같이 반복 굽힘에 의한 IZO 박막의 파괴 거동 변화는 IZO 박막과 기판의 계면구조변화에 기인한 것으로 해석된다. IZO 박막과 기판의 계면에 $SiO_x$ 층을 삽입함으로써 계면 접합강도가 향상되었을 것으로 추측된다. 따라서 변형에 대한 파괴 저항 특성이 우수한 투명전도성 산화물 박막의 형성을 위해서는 적절한 계면구조 제어를 통한 계면 접합 특성의 향상이 필요하다.

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Reliability Assessment of Lead-contained and Lead-free BGA Solder Joints under Cyclic Bending Loads (굽힘 하중하에서 유연 및 무연 솔더 조인트의 신뢰성 평가)

  • Kim Il-Ho;Lee Soon-Bok
    • Journal of the Microelectronics and Packaging Society
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    • v.13 no.1
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    • pp.63-72
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    • 2006
  • Mobile products, such as cellular phones, PDA and notebook, are subjected to many different mechanical loads, which include bending, twisting, impact shock and vibration. In this study, a cyclic bending test of the BGA package was performed to evaluate the fatigue life. Special bending tester, which was suitable for electronic package, was developed using an electromagnetic actuator. A nonlinear finite element model was used to simulate the mechanical bending deformation of solder joint in BGA packages. The fatigue life of lead-free (95.5Sn4.0Ag0.5Cu) solder joints was compared with that of lead-contained (63Sn37Pb). When the applied load to the specimen is small, the lead-free solder has longer fatigue life than lead-contained solder. The fatigue crack is initialized at the exterior solder joints and is propagated into the inner solder joints.

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A Four-point Bending Probe Station for Semiconductor Sensor Piezoresistance Measurement (반도체센서 압저항 측정을 위한 4점 굽힘 프로브 스테이션)

  • Jeon, Ji Won;Kwon, Sung-Chan;Park, Woo-Tae
    • Journal of the Microelectronics and Packaging Society
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    • v.20 no.4
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    • pp.35-39
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    • 2013
  • A four point bending apparatus has been developed to measure semiconductor sensor piezoresistance inside a four inch probe station. The apparatus has a footprint of $60{\times}83mm^2$ and can apply $10{\mu}m$ displacements using a vertical micrometer stage. We used finite element analysis to predict and improve the accuracy of the instrument. Finally strain gauge attached on a silicon test piece was used to experimentally verify the setup.

Bending Behaviors of Stainless Steel Tube Filled with Al5Si4Cu4Mg Closed Cell Aluminum Alloy Foam (발포 Al5Si4Cu4Mg 알루미늄 합금이 충진된 304 스테인리스강 원통의 굽힘저항 특성)

  • Kim, Am-Kee;Lee, Hyo-Jin;Cho, Seong-Seock
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.27 no.10
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    • pp.1686-1694
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    • 2003
  • The foam-filled tube beams can be used for the front rail and firewall structures to absorb impact energy during frontal or side collision of vehicles. In the case of side collision where bending is involved in the crushing mechanism, the foam filler would be effective in maintaining progressive crushing of the thin-walled structures so that much impact energy could be absorbed. In this study, bending behaviors of the closed-cell-aluminum-alloy-foam-filled stainless steel tube were investigated. The various foam-filled specimens including piecewise fillers were prepared and tested. The aluminum-alloy-foam filling offered the significant increase of bending resistance. Their suppression of the inward fold formation at the compression flange as well as the multiple propagating folds led to the increase of load carrying capacity of specimens. Moreover, the piecewise foams would provide the easier way to fill the thin-walled shell structures without the drawback of strength.

Elastic Properties and Repeated Deformation Reliabilities of Stiffness-Gradient Stretchable Electronic Packages (강성도 경사형 신축 전자패키지의 탄성특성 및 반복변형 신뢰성)

  • Han, Kee Sun;Oh, Tae Sung
    • Journal of the Microelectronics and Packaging Society
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    • v.26 no.4
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    • pp.55-62
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    • 2019
  • Stiffness-gradient stretchable electronic packages of the soft PDMS/hard PDMS/FPCB structure were processed using the polydimethylsiloxane (PDMS) as the base substrate and the more stiff flexible printed circuit board (FPCB) as the island substrate. The elastic characteristics of the stretchable packages were estimated and their long-term reliabilities on stretching cycles and bending cycles were characterized. With 0.28 MPa, 1.74 MPa, and 1.85 GPa as the elastic moduli of the soft PDMS, hard PDMS, and FPCB, respectively, the effective elastic modulus of the soft PDMS/hard PDMS/FPCB package was estimated as 0.6 MPa. The resistance of the stretchable packages varied for 2.8~4.3% with stretching cycles ranging at 0~0.3 strain up to 15,000 cycles and for 0.9~1.5% with 15,000 bending cycles at a bending radius of 25 mm.

Manufacture and Bending Behavior of Stainless Steel Cylindrical Shell Filled with Aluminum Alloy Foam (다공성 알루미늄 합금이 충진된 스테인레스 강 원통 Shell의 제조 및 굽힘거동)

  • Kim, Am-Kee;Lee, Hyo-Jin;Cho, Seong-Seock
    • Proceedings of the KSME Conference
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    • pp.19-24
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    • 2003
  • Potential applications of foam-filled section are the automotive structures. A foam-filled section can be used for the front rail and firewall structures to absorb impact energy during frontal or side collision. In the case of side collision where bending is involved in the crushing mechanics, the foam filler will be significant in maintaining progressive crushing of the thin-walled structures so that more impact energy can be absorbed. In this study, the manufacturing process of closed cell aluminum alloy foam filled stainless steel tube was studied, and the various foam filled specimens including piecewise fillers were prepared, tested and discussed about the bending behaviors.

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Control of an Artificial Arm using Flex Sensor Signal (굽힘 센서신호를 이용한 인공의수의 제어)

  • Yoo, Jae-Myung;Kim, Young-Tark
    • Journal of Korean Institute of Intelligent Systems
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    • v.17 no.6
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    • pp.738-743
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    • 2007
  • In this paper, a muscle motion sensing system and an artificial arm control system are studied. The artificial arm is for the people who lost one's forearm. The muscle motion sensing system detect the intention of motion from the upper arm's muscle. In sensing system we use flex sensors which is electrical resistance type sensor. The sensor is attached on the biceps brachii muscle and coracobrachialis muscle of the upper arm. We propose an algorithm to classify the one's intention of motions from the sensor signal. Using this algorithm, we extract the 4 motions which are flexion and extension of the forearm, pronation and supination of the arm. To verify the validity of the proposed algorithms we made experiments with two d.o.f. artificial arm. To reduce the control errors of the artificial arm we also proposed a fuzzy PID control algorithm which based on the errors and error rate.

Power Generation Properties and Bending Characteristics of a Flexible Thermoelectric Module Fabricated using PDMS Filling Method (PDMS 충진법을 이용하여 형성한 유연열전모듈의 발전특성과 굽힘특성)

  • Han, Kee Sun;Oh, Tae Sung
    • Journal of the Microelectronics and Packaging Society
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    • v.26 no.4
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    • pp.119-126
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    • 2019
  • A flexible thermoelectric module, which consisted of 18 pairs of Bi2Te3-based hot-pressed p-n thermoelectric legs, were processed by filling the module inside with polydimethylsiloxane (PDMS) and removing the top and bottom substrates. Its power generation properties and bending characteristics were measured. With putting the flexible module on the wrist, an open circuit voltage of 2.23 mV and a maximum output power of 1.69 ㎼ were generated during staying still. On the other hand, an open circuit voltage of 3.32 mV and a maximum output power of 3.41 ㎼ were obtained with walking motion. The resistance variation of the module was kept below 1% even after applying 30,000 bending cycles with a bending curvature radius of 25 mm.