• Title/Summary/Keyword: CTE

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The Influence of Encapsulation Layer Incorporated into Flexible Substrates for Bending Stress (Flexible 기판의 Bending Stress에 대한 Encapsulation Layer의 영향)

  • Park, Jun-Baek;Seo, Dae-Shik;Lee, Sang-Keuk;Lee, Joon-Ung;Kim, Yong-Hoon;Moon, Dae-Gyu;Han, Jeong-In
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • 2003.11a
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    • pp.473-476
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    • 2003
  • This paper shows necessity of encapsulation layer to maximite flexibility of brittle indium-tin-oxide (ITO) on polymer substrates. And, Young's modulus (E) of encapsulation layer have an significant effect on external bending stress and the coefficient of thermal expansion (CTE) of that have a significant effect on internal thermal stress. To compare magnitude of total mechanical stress including both bending stress and thermal stress, the mechanical stress of triple-layer structure (substrate / ITO / encapsulation layer or substrate / buffer layer / ITO) can be quantified and numerically analyzed through the farthest cracked island position. As a result, it should be noted that multi-layer structures with more elastic encapsulation material have small mechanical stress compared to that of buffer and encapsulation structure of large Young's modulus material when they were externally bent.

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A Study on the Mis-align during Fabricated Poly-Si TFT on Polymer substrate (고분자 기판위에 Poly-Si TFT 제작시 Mis-align방지를 위한 연구)

  • Kang, Su-Hee;Hwang, Jung-Yeon;Seo, Dae-Shik;Kim, Young-Hun;Moon, Dae-Kyu;Han, Jung-In
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • 2005.05a
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    • pp.173-176
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    • 2005
  • Teijin사의 HT100-B60의 폴리카보네이트(polycarbonate) $100{\mu}m$, I-Component사의 PES(polyethersulfone) $200{\mu}m$, Ferrania사의 PAR(polyacrylate) $100{\mu}m$$200{\mu}m$를 사용하였다 열팽창계수의 차이로 인해 공정상 기판의 가열과 냉각시 열응력이 발생하여 기판의 크랙발생의 원인이 된다. 이를 최소화하기 위해 모든 공정이 시작하기 전에 pre-annealing을 통해 plastic 기판의 시간별 공정을 실시하였다. plastic film의 annealing time은 0h, 12h, 24, 40h, 50h, 60h, 70h, 80h으로 사간을 달리하여 오븐 안의 진공상태를 조성하여 실험하였다. Thermal evaporator로 Al을 약 170nm 증착하였으며 (주)동진 세미캠의 DTFR-1011s DR LCD용 감광액을 Spin Coating Spread(500rpm/6sec), Spin(3000rpm/20sec)으로 coating하였다.

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Synthesis and Characterization of Colorless Polyimide Nanocomposite Films Containing Pendant Trifluoromethyl Groups

  • Jin, Hyo-Seong;Chang, Jin-Hae;Kim, Jeong-Cheol
    • Macromolecular Research
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    • v.16 no.6
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    • pp.503-509
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    • 2008
  • A series of colorless polyimide (PI) nanocomposite films were synthesized from 2,2'-bis(3,4-dicarboxyphenyl)hexafluoropropane dianhydride (6FDA) and 2,2'-bis(trifluoromethyl)-4,4'-diaminobiphenyl (TFDB) with various organoclay contents by solution intercalation polymerization to poly(amic acid)s, followed by thermal imidization. The variation with the organoclay content of the thermomechanical properties, morphology, and optical transparency of the hybrids was examined at organoclay loadings ranging from 0 to 1.0 wt%. The hybrid films showed high optical transparency and almost no color, with cut-off wavelengths ranging from 352 and 356 nm and very low $b^*$ values of 1.19-1.77. The hybrid PI films showed good thermal properties with a glass transition temperature of $280-287^{\circ}C$. Most films did not show any significant thermal decomposition below $490^{\circ}C$. The addition of only a small amount of organoclay was sufficient to improve the tensile properties of the PI films with maximum enhancement being observed at 0.25 wt% organoclay. Moreover, these PI hybrids also had low coefficients of thermal expansion (CTE).

Accelerated Thermo-Mechanical Fatigue Life of Pb-Free Solder Joints for PZT Ceramic Resonator (PZT 세라믹 레조네이터 무연솔더 접합부의 열-기계적 피로 가속수명)

  • Hong, Won-Sik;Park, No-Chang;Oh, Chul-Min
    • Korean Journal of Materials Research
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    • v.19 no.6
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    • pp.337-343
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    • 2009
  • In this study, we optimized Pb-free Sn/Ni plating thickness and conditions were optimized to counteract the environmental regulations, such as RoHS and ELV(End-of Life Vehicles). The $B_{10}$ life verification method was also suggested to have been successful when used with the accelerated life test(ALT) for assessing Pb-free solder joint life of piezoelectric (PZT) ceramic resonator. In order to evaluate the solder joint life, a modified Norris-Landzberg equation and a Coffin-Manson equation were utilized. Test vehicles that were composed of 2520 PZT ceramic resonator on FR-4 PCB with Sn-3.0Ag-0.5Cu for ALT were manufactured as well. Thermal shock test was conducted with 1,500 cycles from $(-40{\pm}2)^{\circ}C$ to $(120{\pm}2)^{\circ}C$, and 30 minutes dwell time at each temperature, respectively. It was discovered that the thermal shock test is a very useful method in introducing the CTE mismatch caused by thermo-mechanical stress at the solder joints. The resonance frequency of test components was measured and observed the microsection views were also observed to confirm the crack generation of the solder joints.

The Effect of Heat Treatment on the Thermal Expansion Behavior of Electroformed Nano-crystalline Fe-42 wt%Ni Alloy

  • Lee, Minsu;Han, Yunho;Yim, Tai Hong
    • Journal of the Korean institute of surface engineering
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    • v.47 no.6
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    • pp.293-296
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    • 2014
  • Fe-Ni has been of great interest because it is known as one of low thermal expansion alloys as various application areas. This alloy was fabricated by electroforming process, and effect of heat treatment on thermal expansion and hardness was investigated. Nano-crystalline structure of 13.3 - 63.5 nm in size was observed in the as-deposited alloy. To investigate the effect of heat treatment on grain growth and mechanical/thermal properties, we conducted hardness and coefficient of thermal expansion (CTE). From this, we confirmed these properties were varied by heat treatment. In this nano-crystalline alloy, we could observe abnormal behavior in thermal expansion between $350-400^{\circ}C$. Additionally, an abrupt change in hardness has also been observed. However, once the grains grow up to micro-sized the mechanical and thermal properties mentioned above were stabilized similar to those of bulk alloys due to heat treatment.

Genotoxic Effects of Volatile Organic Compounds in Water (물속 휘발성 유기화합물이 염색체 돌연변이에 미치는 영향)

  • Jung Kyu Saeng;Lee Chae Yang;Shin Heuyn Kil;Lee Ki Nam;Jeung Jae Yeal;Lee Jong Young
    • Journal of Physiology & Pathology in Korean Medicine
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    • v.16 no.5
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    • pp.899-904
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    • 2002
  • For determination of the genotoxicity of VOCs(Volatile Organic Compounds) in water, in vitro Comet assay was performed using 3T3 cells. The selected 5 VOCs; Trichloroethylene(TCE), Tetrachloroethylene(PCE), Carbontetrachloride (CteC), Dichloromethane(DCM) and Chlorofrom(Chl) and mixed solvent(Mix), are the test items for drinking water quality. Author analyzed the genotoxicity of these solvents through their tail length (TL) values. Mix, PCE, Chl, TCE in order had cytotoxicity at the highest concentration, and CCl₄ and DCM had no cytotoxic effect. TCE, CCl₄, Chl, PCE, Mix, DCM had genotoxicity, Chl, PCE, Mix had both cytotoxicity and genotoxicity simultaneously, Cytotoxic effect of mixed organic solvents, compared with that of single component, at each concentration, was influenced by the synergistic effect of the interaction of each organic component.

Synthesis and Characterization of Polyimide/silica Hybrid Films Derived from Silane Oligomer Containing Epoxy Group (에폭시 그룹을 함유한 실란 올리고머의 합성과 그로부터 유도된 폴리이미드/실리카 혼성 필름의 특성)

  • Lee, Jun Hyuk;Park, Yun Jun;Choi, Jong-Ho;Nam, Sang Yong;Kim, Sung Won;Hong, Young Taik
    • Journal of Adhesion and Interface
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    • v.10 no.2
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    • pp.98-105
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    • 2009
  • Poly(amic acid) was synthesized from the reaction of p-PDA/ODA and PMDA/BPDA and silane oligomer containing epoxy group was also synthesized from the reaction of tetramethylorthosilicate (TMOS) and glycidol. After hybridizing poly (amic acid) and silane oligomer, they were effectively converted into polyimide/silica hybrid films by thermal imidization process. As the silica contents in hybrid films increased, CTE values decreased from 17 ppm/K to 10 ppm/K and the tensile modulus increased, in spite of decreasing tensile strength. In addition, the peel test showed that the adhesion strength of hybrid film was enhanced from $0.43kg_f/cm$ to $1.02kg_f/cm$. Therefore, it could be concluded that the polyimide/silica hybrid film is effective to enhance adhesion strength for FCCL films.

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Effects of thermal annealing of AlN thin films deposited on polycrystalline 3C-SiC buffer layer (다결정 3C-SiC 버퍼층위 증착된 AlN 박막의 열처리 효과)

  • Hong, Hoang-Si;Chung, Gwiy-Sang
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • 2009.11a
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    • pp.112-112
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    • 2009
  • In this study, the effect of a long post-deposition thermal annealing(600 and 1000 $^{\circ}C$) on the surface acoustic wave (SAW) properties of polycrystalline (poly) aluminum-nitride (AlN) thin films grown on a 3C-SiC buffer layer was investigates. The poly-AlN thin films with a (0002) preferred orientation were deposited on the substrates by using a pulsed reactive magnetron sputtering system. Experimental results show that the texture degree of AlN thin film was reduced along the increase in annealing temperature, which caused the decrease in the electromechanical coupling coefficient ($k^2$). The SAW velocity also was decreased slightly by the increase in root mean square (RMS) roughness over annealing temperature. However, the residual stress in films almost was not affect by thermal annealing process due to small lattice mismatch different and similar coefficient temperature expansion (CTE) between AlN and 3C-SiC. After the AlN film annealed at 1000 $^{\circ}C$, the insertion loss of an $IDT/AlN/3C-SiC/SiO_2/Si$ structure (-16.44 dB) was reduced by 8.79 dB in comparison with that of the as-deposited film (-25.23 dB). The improvement in the insertion loss of the film was fined according to the decrease in the grain size. The characteristics of AlN thin films were also evaluated using Fourier transform-infrared spectroscopy (FT-IR) spectra and X-ray diffraction (XRD), scanning electron microscopy (SEM), and atomic force microscopy (AFM) images.

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Effect of a 3C-SiC buffer layer on SAW properties of AlN films (3C-SiC 버퍼층이 AlN 박막형 SAW 특성에 미치는 영향)

  • Hoang, Si-Hong;Chung, Gwiy-Sang
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • 2009.06a
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    • pp.235-235
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    • 2009
  • This paper describes the influence of a polycrystalline (poly) 3C-SiC buffer layer on the surface acoustic wave (SAW) properties of poly aluminum nitride (AlN) thin films by comparing the center frequency, insertion loss, the electromechanical coupling coefficient ($k^2$), andthetemperaturecoefficientoffrequency(TCF) of an IDT/AlN/3C-SiC structure with those of an IDT/AlN/Si structure, The poly-AlN thin films with an (0002)-preferred orientation were deposited on a silicon (Si) substrate using a pulsed reactive magnetron sputtering system. Results show that the insertion loss (21.92 dB) and TCF (-18 ppm/$^{\circ}C$) of the IDT/AlN/3C-SiC structure were improved by a closely matched coefficient of thermal expansion (CTE) and small lattice mismatch (1 %) between the AlN and 3C-SiC. However, a drawback is that the $k^2(0.79%)$ and SAW velocity(5020m/s) of the AlN/3C-SiC SAW device were reduced by appearing in some non-(0002)AlN planes such as the (10 $\bar{1}$ 2) and (10 $\bar{1}$ 3) AlN planes in the AlN/SiC film. Although disadvantages were shown to exist, the use of the AlN/3C-SiC structure for SAW applications at high temperatures is possible. The characteristics of the AlN thin films were also evaluated using FT-IR spectra, XRD, and AFM images.

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Health Risk Assessment by Potential Exposure of NO2 and VOCs in Apartments (공동주택내 이산화질소(NO2) 및 휘발성유기화합물(VOCs) 노출에 따른 건강 위해성 평가)

  • Jung, Soon-Won;Yang, Won-Ho;Son, Bu-Soon
    • Journal of Environmental Health Sciences
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    • v.33 no.4
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    • pp.242-249
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    • 2007
  • Indoor air quality has become a topic of interest and concern. Especially changes in construction design and the increased use of synthetic products may result in an increasing of complaints and health effects about the quality of indoor air at home. In this study, nitrogen dioxide($NO_2$) and volatile organic compounds(VOCs) within new and established apartments on the basis of 4 years of building year were measured every 3 days consecutively during 60 days. We selected each 10 house in Seoul, Asan and Daegu, respectively, and produced risk numbers for hazard quotients, and predicted increases in incidence of cancer. The calculations were made for the adult with default exposure values and also made for a worst case scenario using Monte-Carlo simulation as describing the reasonable exposure(RME). Mean of Monte carlo analysis by benzene, in the construction under 4 years (male: $9.2{\times}10^{-5}$, female: $1.0{\times}10^{-4}$) and over 4 years (male: $6.8{\times}10^{-5}$, female: $8.3{\times}10^{-5}$) exceeded $10^{-6}$ of permitted standards in US EPA, RME of Monte carlo analysis. In construction under 4 yews (male: $9.9{\times}10^{-3}$, female: $9.6{\times}10^{-3}$) and over 4 years (male: $9.8{\times}10^{-3}$, female: $7.8{\times}10^{-3}$) exceeded $10^{-4}$ of maximum permitted standards in US EPA. The hazard index of non-carcinogenic pollutants by nitrogen dioxide, toluene, m,p-xylene and o-xylene, both male and female in apartment constructed under 4 yews and over 4 years was found less than the permitted standards of hazardous health effects in CTE. Significant cancer risks and non-cancer hazard quotients were predicted in under 4 yews of building year.