• Title/Summary/Keyword: CTE

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Carbon/Epoxy Grid Structure with Near Zero CTE in 3-D Direction (3차원 방향으로 극소 열팽창계수를 갖는 탄소/에폭시 복합재료 격자 구조물)

  • 이형주;김창근;윤광준;박훈철
    • Proceedings of the Korean Society For Composite Materials Conference
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    • 1999.11a
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    • pp.272-276
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    • 1999
  • The present paper proposes design and manufacturing methods of the carbon/epoxy square grid structure with near zero-CTE in three geometrical principal directions. Bonding strength of the grid structure is examined for different bonding methods. Numerical examples show that maximum displacement of the composite grid structure is almost zero comparing with that of aluminum grid structure with same dimension under thermal loading.

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Highly filled AIN/epoxy composites for microelectronic encapsulation (반도체 봉지용 고충진 AIN/Epoxy 복합재료)

  • 배종우;김원호;황영훈
    • Proceedings of the Korean Society For Composite Materials Conference
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    • 2000.04a
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    • pp.131-134
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    • 2000
  • Increased temperature adversely affects the reliability of a device. So, package material should have high thermal diffusion, i.e., high thermal conductivity. And, there are several other physical properties of polymeric materials that are important to microelectronics packaging, some of which are a low dielectric constant, a low coefficient of thermal expansion (CTE), and a high flexural strength. In this study, to get practical maximum packing fraction of AIN (granular type) filled EMC, the properties such as the spiral flow, thermal conductivity, CTE, and water resistance of AIN-filled EMC (65-vol%) were evaluated according to the size of AIN and the filler-size distribution. Also, physical properties of AIN filled EMC above 65-vol% were evaluated according to increasing AIN content at the point of maximum packing fraction (highly loading condition). The high loading conditions of EMC were set $D_L/D_S$=12 and $X_S$=0.25 like as filler of sphere shape and the AIN filled EMC in this conditions can be obtained satisfactory fluidity up to 70-vol%. As a result, the AIN filled EMC (70-vol%) at high loading condition showed improved thermal conductivity (about 6 W/m-K), dielectric constant (2.0~3.0), CTE(less than 14 ppm/$^{\circ}C$) and water resistance. So, the AIN filled EMC (70-vol%) at high loading condition meets the requirement fur advanced microelectronic packaging materials.

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Evaluation of the Coefficient of Thermal Expansion of Constituents in Composite Materials using an Inverse Analysis Scheme (역해석기법을 이용한 복합재료 구성성분의 열팽창계수 예측)

  • Lim, Jae Hyuk;Sohn, Dongwoo
    • Journal of the Computational Structural Engineering Institute of Korea
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    • v.27 no.5
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    • pp.393-401
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    • 2014
  • In this paper, we propose an evaluation scheme of the coefficients of thermal expansion (CTE) of constituents in composite materials using an inverse analysis. The size of constituents typically is about a few micrometers, which makes the identification of material properties difficult as well as the measurement results inaccurate. The proposed inverse analysis scheme, which is combined with the Mori-Tanaka method for predicting an equivalent CTE of composite materials, provides the CTE of the constituents in a straightforward manner by minimizing the cost function defined in lamina scale with the steepest descent method. To demonstrate the effectiveness and accuracy of the proposed scheme, the CTEs of several fibers (glass fiber, P75, P100, and M55J) embedded in matrix are evaluated and compared with experimental results. Furthermore, we discuss the effects of uncertainty of laminar and matrix properties on the prediction of fiber properties.

A Change of Thermal Expansion Coefficient according to Li2O-added Porcelain for Dental Zirconia (치과용 지르코니아 도재의 Li2O 첨가에 따른 열팽창계수 변화)

  • Yoon, Han-Sok
    • Journal of Technologic Dentistry
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    • v.31 no.4
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    • pp.25-30
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    • 2009
  • Zirconia($ZrO_2$) has attracted much attention in science and technology because of its high refractive index, high melting temperature, hardness, low thermal conductivity and corrosion barrier properties. And it is widely used as the dental restoration material because of its esthetic appearance. In this research, we analyzed the particle size and composition of the imported dental porcelain for zirconia. And the glass frit was produced. To decrease the glass transition temperature and softening temperature of the glass frit, $Li_2O$ was added into it and the effect of $Li_2O$ on the firing temperature was researched. Then the glass which contains leucite crystal with a high coefficient of thermal expansion(CTE) was manufactured and it was mixed with the glass frit to control the CTE. The phase composition were analyzed using the X-ray diffraction. The morphologies of the samples were observed by the scanning electron microscope. The 4wt% $Li_2O$-added glass frit has the optimal glass transition temperature and softening temperature. And 6 wt% leucite crystal was mixed with the glass frit to control the CTE. From the experimental results of crystallization, the crystal phase was found only leucite crystal.

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Effects of Silica Filler and Diluent on Material Properties of Non-Conductive Pastes and Thermal Cycling Reliability of Flip Chip Assembly

  • Jang, Kyung-Woon;Kwon, Woon-Seong;Yim, Myung-Jin;Paik, Kyung-Wook
    • Journal of the Microelectronics and Packaging Society
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    • v.10 no.3
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    • pp.9-17
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    • 2003
  • In this paper, thermo-mechanical and rheological properties of NCPs (Non-Conductive Pastes) depending on silica filler contents and diluent contents were investigated. And then, thermal cycling (T/C) reliability of flip chip assembly using selected NCPs was verified. As the silica filler content increased, thermo-mechanical properties of NCPs were changed. The higher the silica filler content was added, glass transition temperature ($T_g$) and storage modulus at room temperature became higher. While, coefficient of thermal expansion (CTE) decreased. On the other hand, rheological properties of NCPs were significantly affected by diluent content. As the diluent content increased, viscosity of NCP decreased and thixotropic index increased. However, the addition of diluent deteriorated thermo-mechanical properties such as modulus, CTE, and $T_g$. Based on these results, three candidates of NCPs with various silica filler and diluent contents were selected as adhesives for reliability test of flip chip assemblies. T/C reliability test was performed by measuring changes of NCP bump connection resistance. Results showed that flip chip assembly using NCP with lower CTE and higher modulus exhibited better T/C reliability behavior because of reduced shear strain in NCP adhesive layer.

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Reliability Estimation of Solder Joint by Using Failure Probability Model (파손확률 모델을 이용한 솔더 조인트의 건전성 평가)

  • Myoung, No-Hoon;Lee, Ouk-Sub;Kim, Dong-Hyeok
    • Proceedings of the KSME Conference
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    • 2004.04a
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    • pp.365-370
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    • 2004
  • Generally, component and FR-4 board are connected by solder joint. Because material properties of components and FR-4 board are different, component and FR-4 board show different coefficients of thermal expansion (CTE) and thus strains in component and board are different when they are heated. That is, the differences in CTE of component and FR-4 board cause the dissimilarity in shear strain and solder joint' failure. The first order Taylor series expansion of the limit state function incorporating with Tresca failure criterion is used in order to estimate the failure probability of solder joints under heated condition. Using shear stresses and shear strains appeared on the solder joint, we estimate the failure probability of solder joints with the Tresca failure criterion. The effects of random variables such as CTE, distance of the solder joint from the neutral point(DNP), temperature variation and height of solder on the failure probability of the solder joint are systematically studied by using the failure probability model with first order reliability method(FORM).

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A Framework for Deriving Investment Priority in National Defense R&D - Using DEA based on TRA - (국방연구개발 투자우선순위 도출 프레임워크 - TRA 방법론에 기반한 DEA 중심으로 -)

  • Yu, Donghyun;Lim, Dongil;Seol, Hyeonju
    • Journal of the Korea Institute of Military Science and Technology
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    • v.21 no.2
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    • pp.217-224
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    • 2018
  • The purpose of this study is to evaluate the future potential value of CTE(Critical Technology Element)s that are evaluated to be low in TRA(Technology Readiness Assesment) and to present investment prioritization technologies in defense R&D(Research and Development) based on them. To do this, we used the DEA(Data Envelopment Analysis) method, which is useful in evaluating the efficiency of the organization. Specifically, we suggest a systematic framework to evaluate the future value of CTEs by setting the CTEs derived from the TRA process to DMU(Decision Making Unit)s, the cost and time required to develop each CTE as the input factor of the DEA and the effects of the development of each CTE as the output factor of the DEA respectively. We also conducted an illustrative case study on radar technologies to demonstrate the usefulness of the proposed approach.

Synthesis of P2O5-V2O5-ZnO Glass Frit for Laser Sealing of OLED by the Addition of Filler (필러 첨가에 의한 OLED의 레이저 실링용 P2O5-V2O5-ZnO 유리프릿의 제조)

  • Bang, Jae-Chul
    • Journal of the Korean Institute of Electrical and Electronic Material Engineers
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    • v.28 no.9
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    • pp.571-576
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    • 2015
  • In this study, we developed a lead-free $P_2O_5-V_2O_5-ZnO$ glass frit for sealing OLED using laser irradiation. The frit satisfied the characteristics required for laser sealing such as low glass transition temperature, low coefficient of thermal expansion (CTE), high water-resistance, and high absorption at the wavelength of the laser beam. Ceramic fillers were added to the glass frit in order to further reduce and match its CTE with that of the commercial glass substrate. The addition of Zirconium Tungsten Phosphate (ZWP) to the frit yielded the most desirable results, reducing the CTE to $45.4{\times}10^{-7}/^{\circ}C$, which is very close to that of the glass substrate ($44.0{\times}10^{-7}/^{\circ}C$). Successful formation of a solid sealing layer was observed by optical and scanning electron microscopy.