• Title/Summary/Keyword: CRFM

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Measurement of Local Elastic Properties of Flip-chip Bump Materials using Contact Resonance Force Microscopy (접촉 공진 힘 현미경 기술을 이용한 플립 칩 범프 재료의 국부 탄성계수 측정)

  • Kim, Dae-Hyun;Ahn, Hyo-Sok;Hahn, Junhee
    • Tribology and Lubricants
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    • v.28 no.4
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    • pp.173-177
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    • 2012
  • We used contact resonance force microscopy (CRFM) technique to determine the quantitative elastic properties of multiple materials integrated on the sub micrometer scale. The CRFM approach measures the frequencies of an AFM cantilever's first two flexural resonances while in contact with a material. The plain strain modulus of an unknown or test material can be obtained by comparing the resonant spectrum of the test material to that of a reference material. In this study we examined the following bumping materials for flip chip by using copper electrode as a reference material: NiP, Solder (Sn-Au-Cu alloy) and under filled epoxy. Data were analyzed by conventional beam dynamics and contact dynamics. The results showed a good agreement (~15% difference) with corresponding values determined by nanoindentaion. These results provide insight into the use of CRFM methods to attain reliable and accurate measurements of elastic properties of materials on the nanoscale.

A Numerical Study of the Effect of Small Passenger Car's Grille Shape on the Aerodynamic Performance (소형 승용 차량의 그릴 형상이 차량의 공력 성능에 미치는 영향에 관한 수치해석 연구)

  • Kim, Jaemin;Cho, Hyeongkyu;Kim, Taekgi;Kim, Moonsang;Kim, Yongsuk;Kim, Yongnyun
    • Transactions of the Korean Society of Automotive Engineers
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    • v.23 no.1
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    • pp.74-87
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    • 2015
  • A numerical parametric study has been accomplished to figure out the effect of grille shape built in a small passenger car on the aerodynamic performance such as drag and mass flow rate through CRFM(Condenser Radiator Fan Module). Three grille opening parameters and three grille mesh parameters are selected and adopted to a simple shape passenger car model. This research will provide a design guideline for grille opening geometry and mesh shape in the grille. FLUENT, which is very well known commercial code, hires k-${\epsilon}$ turbulence model at the driving speed of 110km/h with moving wall boundary condition. A porous media condition is prepared to estimate the pressure drop amount through CRFM parts.