• Title/Summary/Keyword: $Moir{\acute{e}}$ Interferometry

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Nano-level High Sensitivity Measurement Using Microscopic Moiré Interferometry (마이크로 무아레 간섭계를 이용한 초정밀 변형 측정)

  • Joo, Jin-Won;Kim, Han-Jun
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.32 no.2
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    • pp.186-193
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    • 2008
  • [ $Moir{\acute{e}}$ ] interferometry is an optical method, providing whole field contour maps of in-plane displacements with high resolution. The demand for enhanced sensitivity in displacement measurements leads to the technique of microscopic $moir{\acute{e}}$ interferometry. The method is an extension of the $moir{\acute{e}}$ interferometry, and employs an optical microscope for the required spatial resolution. In this paper, the sensitivity of $moir{\acute{e}}$ interferometry is enhanced by an order of magnitude using an immersion interferometry and the optical/digital fringe multiplication(O/DFM) method. In fringe patterns, the contour interval represents the displacement of 52 nm per fringe order. In order to estimate the reliability and the applicability of the optical system implemented, the measurements of rigid body displacements of grating mold and the coefficient of thermal expansion(CTE) for an aluminium block are performed. The system developed is applied to the measurement of thermal deformation in a flip chip plastic ball grid array package.

Thermomechanical and Flexural Behavior of WB-PBGA Package Using $Moir{\acute{e}}$ Interferometry (모아레 간섭계를 이용한 WB-PBGA 패키지의 온도변화 및 굽힘하중에 대한 거동해석)

  • Joo, Jin-Won;Lee, Chang-Hee;Han, Bong-Tae;Cho, Seung-Min
    • Proceedings of the KSME Conference
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    • 2001.06a
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    • pp.90-95
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    • 2001
  • Thermo-mechanical and flexural behavior of a wire-bond plastic ball grid array (WB-PBGA) are characterized by high sensitive $moir{\acute{e}}$ interferometry. $Moir{\acute{e}}$ fringe patterns are recorded and analyzed at several various bending loads and temperature steps. At the temperature higher that $100^{\circ}C$, the inelastic deformation in solder balls became more dominant. As a result the bending of the molding compound decreased while temperature increased. The strain results show that the solder ball located at the edge of the chip has largest shear strain by the thermal load while the maximum average shear strain by the bending moment occurs in the end solder. The results also show that $moir{\acute{e}}$ interferometry is a powerful and effective tool in experimental studies of electronic packaging.

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Thermo-mechanical Analysis of Filp Chip PBGA Package Using $Moir\acute{e}$ Interferometry (모아레 간섭계를 이용한 Flip Chip PBGA 패키지의 온도변화에 대한 거동해석)

  • Kim, Do-Hyung;Choi, Yong-Seo;Joo, Jin-Won
    • Proceedings of the KSME Conference
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    • 2003.11a
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    • pp.1027-1032
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    • 2003
  • Thermo-mechanical behavior of flip-chip plastic ball grid array (FC-PBGA) packages are characterized by high sensitive $Moir{\acute{e}}$ interferometry. $Moir{\acute{e}}$ fringe patterns are recorded and analyzed for several temperatures. Deformation analysis of bending displacements of the packages and average strains in the solder balls for a single-sided package assembly and a double-sided package assembly are presented. The bending displacement of the double-sided package assembly is smaller than that of the single-sided one. The largest of effective strain occurred in the solder ball located at the edge of the chip and its magnitude of the double-sided package assembly is greater than that of single-sided one.

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Deformation Behavior of MEMS Gyroscope Package Subjected to Temparature Change (온도변화에 따른 MEMS 자이로스코프 패키지의 변형측정)

  • Joo, Jin-Won;Choi, Yong-Seo;Choa, Sung-Hoon;Song, C.M.
    • Proceedings of the KSME Conference
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    • 2003.11a
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    • pp.1407-1412
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    • 2003
  • In MEMS devices, packaging induced stress or stress induced structure deformation become increasing concerns since it directly affects the performance of the device. In this paper, deformation behavior of MEMS gyroscope package subjected to temparature change is investigated using high-sensitivity $Moir{\acute{e}}$ interferometry. Using the real-time $Moir{\acute{e}}$ setup, fringe patterns are recorded and analyzed at several temperatures. Temperature dependent analyses of warpages and extensions/contractions of the package are presented. Linear elastic behavior is documented in the temperature region of room temperature to $125^{\circ}C$. Analysis of the package reveals that global bending occurs due to the mismatch of thermal expansion coefficient between the chip, the molding compond and the PCB.

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Two-Wavelength Phase-Shifting Projection $Moir\acute{e}$ Topography for Measurement of Three-Dimensional Profiles with High Step Discontinuities (고단차 불연속 형상의 3차원 측정을 위한 이중파장 위상천이 영사식 무아레)

  • Kim, Seung-Woo;Oh, Jung-Taek;Jung, Moon-Sik;Choi, Yi-Bae
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.23 no.7 s.166
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    • pp.1129-1138
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    • 1999
  • [$Moir\acute{e}$] technique is now being extensively investigated as a fast non-contact means of three-dimensional profile measurement especially for reverse engineering. One problem with $moir\acute{e}$ technique is so called $2\pi$-ambiguity problem that limits the maximum step height difference between two neighboring sampling points to be less than half the equivalent wavelength of $moir\acute{e}$ fringes. In this investigation, a new two-wavelength scheme of projection $moir\acute{e}$ topography is proposed and tested to cope with the $2\pi$-ambiguity problem. Experimental results are discussed to assess the new method in measuring large objects with high step discontinuities.

Inverse Estimation of Viscoplastic Properties of Solder Alloy Using Moir$\acute{e}$ Interferometry and Computer Model Calibration (모아레 간섭계와 모델교정법을 이용한 솔더 합금의 점소성 물성치 역추정)

  • Gang, Jin-Hyuk;Lee, Bong-Hee;Joo, Jin-Won;Choi, Joo-Ho
    • Journal of the Computational Structural Engineering Institute of Korea
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    • v.24 no.1
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    • pp.97-106
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    • 2011
  • In this study, viscoplastic material properties of solder alloy which is used in the electronics packages are inversely estimated. A specimen is fabricated to this end, and an experiment is conducted to examine deformation by Moir$\acute{e}$ interferometry. As a result of the experiment, bending displacement of the specimen and shear strain of the solder are obtained. A viscoplastic finite element analysis procedure is established, and the material parameters are determined to match closely with the experiments. The uncertainties which include inherent experimental error and insufficient data of experiments are addressed by using the method of computer model calibration. As a result, material parameters are identified in the form of confidence interval, and the displacements and strains using these parameters are predicted in the form the prediction interval.

Elastoplastic Behavior and Creep Analysis of Solder in a FC-PBGA Package (플립 칩 패키지 솔더의 탄소성 거동과 크립 해석)

  • Choi, Nam-Jin;Lee, Bong-Hee;Joo, Jin-Won
    • Journal of the Microelectronics and Packaging Society
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    • v.17 no.2
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    • pp.21-28
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    • 2010
  • Creep behaviors of the solder balls in a flip chip package assembly during thermal cycling test is investigated.. A material models used in the finite element analysis are viscoplastic model introduced by Anand and creep model called partitioned model. Experiment of two temperature cycles using moir$\acute{e}$ interferometry is conducted to verify the reliability of material models for the analysis of thermo-mechanical behavior. Bending deformations of the assemblies and average strains of the solder balls due to temperature change and dwell time are investigated. The results show that time-dependent shear strain of solder by the partitioned model is in excellent agreement with those by moir$\acute{e}$ interferometry, while there is considerable difference between results by Anand model and experiment. In this paper, the partitioned model is employed for the time-dependent creep analysis of the FC-PBGA package. It is also shown that the thermo-mechanical stress becomes relaxed by creep behavior at high temperature during temperature cycles.

The Effect of Finite Element Models in Thermal Analysis of Electronic Packages (반도체 패키지의 열변형 해석 시 유한요소 모델의 영향)

  • Choi, Nam-Jin;Joo, Jin-Won
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.33 no.4
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    • pp.380-387
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    • 2009
  • The reliability concerns of solder interconnections in flip chip PBGA packages are produced mainly by the mismatch of coefficient of thermal expansion(CTE) between the module and PCB. Finite element analysis has been employed extensively to simulate thermal loading for solder joint reliability and deformation of packages in electronic packages. The objective of this paper is to study the thermo-mechanical behavior of FC-PBGA package assemblies subjected to temperature change, with an emphasis on the effect of the finite element model, material models and temperature conditions. Numerical results are compared with the experimental results by using $moir{\acute{e}}$ interferometry. Result shows that the bending displacements of the chip calculated by the finite element analysis with viscoplastic material model is in good agreement with those by $moir{\acute{e}}$ inteferometry.

Material Parameters Identification of Adhesive in Layered Plates Using Moiré Interferomety and Optimization Technique (무아레 간섭계 측정과 최적화 기법을 이용한 적층판의 접착제 물성치 규명)

  • Joo, Jin-Won;Kim, Han-Jun;Lee, Woo-Hyuk;Kim, Jin-Young;Choi, Joo-Ho
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.31 no.11
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    • pp.1100-1107
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    • 2007
  • In this study, a method to characterize material properties of adhesive that is used in a layered plates bonding process is developed by combined evaluation of experiment, simulation and optimization technique. A small bonded specimens of rectangular plate are prepared to this end, and put into a thermal loading conditions. $Moir{\acute{e}}$ interferomety is used to measure submicron displacements occurred during the process. The elevated temperature is chosen as control factors. FE analysis with constant values for the adhesive materials is also carried out to simulate the experiment. Significant differences are observed from the two results, in which the simulation predicts the monotonic increase of the bending displacement whereas the measurement shows decrease of the displacement at above $75^{\circ}C$. In order to minimize the difference of the two, material parameters of the adhesive at a number of different temperatures are posed as unknowns to be determined, and optimization is conducted. As a result, optimum material parameters are found that excellently matches the simulation and experiment, which are decreased with respect to the temperature.

Talbot Interferometry for Measuring the Focal Length of a Lens without Moiré Fringes

  • Lee, Sukmock
    • Journal of the Optical Society of Korea
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    • v.19 no.2
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    • pp.165-168
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    • 2015
  • A simple method to determine the focal length of a lens using the Talbot image is presented. This method uses only one grating, requiring neither Moir$\acute{e}$ fringe analysis nor the angle between the gratings. The original Fourier transform was used to access the spectrum beyond the limitation set of the usual fast Fourier transform to determine the (de)magnification accurately enough to be used for the focal length. A set of Talbot images simulated numerically with the Fresnel diffraction integral was used to demonstrate the method. For focal lengths between 5550 mm and 5650 mm, the mean difference between the focal lengths determined from the Talbot images and the true values was 3.3 mm with the standard deviation of the difference being 3.8 mm. The true focal lengths can be recovered with an accuracy of 0.06%.