• Title/Summary/Keyword: CTE Mismatch

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Evaluation of Temperature-dependency of CTE of Materials for MEMS Using ESPI (ESPI를 이용한 MEMS용 소재의 열팽창 계수 온도 의존성 평가)

  • Kim, Dong-Won;Kim, Hong-Jae;Lee, Nak-Kyu;Choi, Tae-Hoon;Na, Kyoung-Hoan;Kwon, Dong-Il
    • Proceedings of the KSME Conference
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    • 2003.04a
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    • pp.1315-1320
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    • 2003
  • The thermal expansion coefficient, which causes the micro failure at the interfacial state of thin films is necessary to consider for proper designing MEMS. The effect of temperature on the coefficient of thermal expansion(CTE) of $SiO_2$ and $Si_3N_4$ film was investigated. Thermal strain induced by mismatch of CTE between substrate and thin film continuously measured with resolution-improved electronic speckle pattern interferometry(ESPI). The thermal stress induced by mismatch of CTE derivate through thermal strain. The thermal expansion coefficients of thin film were calculated with the general equation of CTE and thermal stress in thin films, and it confirmed that CTE of $SiO_2$changed from $0.25{\times}10^{-6}/^{\circ}C$ to $1.4{\times}10^{-6}/^{\circ}C$ with temperature increasing from 50 to $600^{\circ}C$

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Development of SiC Composite Solder with Low CTE as Filling Material for Molten Metal TSV Filling (용융 금속 TSV 충전을 위한 저열팽창계수 SiC 복합 충전 솔더의 개발)

  • Ko, Young-Ki;Ko, Yong-Ho;Bang, Jung-Hwan;Lee, Chang-Woo
    • Journal of Welding and Joining
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    • v.32 no.3
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    • pp.68-73
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    • 2014
  • Among through silicon via (TSV) technologies, for replacing Cu filling method, the method of molten solder filling has been proposed to reduce filling cost and filling time. However, because Sn alloy which has a high coefficient of thermal expansion (CTE) than Cu, CTE mismatch between Si and molten solder induced higher thermal stress than Cu filling method. This thermal stress can deteriorate reliability of TSV by forming defects like void, crack and so on. Therefore, we fabricated SiC composite filling material which had a low CTE for reducing thermal stress in TSV. To add SiC nano particles to molten solder, ball-typed SiC clusters, which were formed with Sn powders and SiC nano particles by ball mill process, put into molten Sn and then, nano particle-dispersed SiC composite filling material was produced. In the case of 1 wt.% of SiC particle, the CTE showed a lowest value which was a $14.8ppm/^{\circ}C$ and this value was lower than CTE of Cu. Up to 1 wt.% of SiC particle, Young's modulus increased as wt.% of SiC particle increased. And also, we observed cross-sectioned TSV which was filled with 1 wt.% of SiC particle and we confirmed a possibility of SiC composite material as a TSV filling material.

Warpage Simulation by the CTE mismatch in Blanket Structured Wafer Level 3D packaging

  • Kim, Seong Keol;Jang, Chong-Min;Hwang, Jung-Min;Park, Man-Chul
    • Journal of the Korean Society of Manufacturing Technology Engineers
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    • v.22 no.1
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    • pp.168-172
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    • 2013
  • In 3D wafer-stacking technology, one of the major issues is wafer warpage. Especially, The important reason of warpage has been known due to CTE(Coefficient of Thermal Expansion) mismatch between materials. It was too hard to choose how to make the FE model for blanket structured wafer level 3D packaging, because the thickness of each layer in wafer level 3D packaging was too small (micro meter or nano meter scale) comparing with diameter of wafer (6 or 8 inches). In this study, the FE model using the shell element was selected and simulated by the ANSYS WorkBench to investigate effects of the CTE on the warpage. To verify the FE model, it was compared by experimental results.

Submicro-displacement Measuring System with Moire Interferometer and Application to the Themal Deformation of PBGA Package (무아레 간섭계 초정밀 변위 측정장치의 설계 및 PBGA 패키지 열변형 측정에의 응용)

  • Oh, Ki-Hwan;Joo, Jin-Won
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.28 no.11
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    • pp.1646-1655
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    • 2004
  • A description of the basic principles of moire interferometry leads to the design of a eight-mirror four-beam interferometer for obtaining fringe patterns representing contour-maps of in-Plane displacements. The technique is implemented by the optical system using an environmental chamber for submicro-displacement mesurement. In order to estimate the reliability and applicabili쇼 of the system developed, the measurement of coefficient of thermal expansion (CTE) for a aluminium block is performed. Consequently, the system is applied to the measurement of thermal deformation of a WB-PBGA package assembly. Temperature dependent analyses of global and local deformations are presented to study the effect of the mismatch of CTE between materials composed of the package assemblies. Bending displacements of the packages and average strains of solder balls are documented. Thermal induced displacements calculated by FEM agree quantitatively with experimental results.

The Effect of Insulating Material on WLCSP Reliability with Various Solder Ball Layout (솔더볼 배치에 따른 절연층 재료가 WLCSP 신뢰성에 미치는 영향)

  • Kim, Jong-Hoon;Yang, Seung-Taek;Suh, Min-Suk;Chung, Qwan-Ho;Hong, Joon-Ki;Byun, Kwang-Yoo
    • Journal of the Microelectronics and Packaging Society
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    • v.13 no.4
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    • pp.1-7
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    • 2006
  • A major failure mode for wafer level chip size package (WLCSP) is thermo-mechanical fatigue of solder joints. The mechanical strains and stresses generated by the coefficient of thermal expansion (CTE) mismatch between the die and printed circuit board (PCB) are usually the driving force for fatigue crack initiation and propagation to failure. In a WLCSP process peripheral or central bond pads from the die are redistributed into an area away using an insulating polymer layer and a redistribution metal layer, and the insulating polymer layer affects solder joints reliability by absorption of stresses generated by CTE mismatch. In this study, several insulating polymer materials were applied to WLCSP to investigate the effect of insulating material. It was found that the effect of property of insulating material on WLCSP reliability was altered with a solder ball layout of package.

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Effect analysis of thermal-mechanical behavior on fatigue crack of flip-chip electronic package (플립 칩 전자 패키지의 피로 균열이 미치는 열적 기계적 거동 분석)

  • Park, Jin-Hyoung;Lee, Soon-Bok
    • Proceedings of the KSME Conference
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    • 2007.05a
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    • pp.1673-1678
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    • 2007
  • The use of flip-chip type electronic package offers numerous advantages such as reduced thickness, improved environmental compatibility, and downed cost. Despite numerous benefits, flip-chip type packages bare several reliability problems. The most critical issue among them is their electrical performance deterioration upon consecutive thermal cycles attributed to gradual delamination growth through chip and adhesive film interface induced by CTE mismatch driven shear and peel stresses. The electronic package in use is heated continuously by itself. When the crack at a weak site of the electronic package occurs, thermal deformationon the chip side is changed. Therefore, we can measure these micro deformations by using Moire interferometry and find out the crack length.

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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.

A study on Electrical Characteristic and Thermal Shock Property of TSV for 3-Dimensional Packaging (3차원 패키징용 TSV의 열응력에 대한 열적 전기적 특성)

  • Jeong, Il Ho;Kee, Se Ho;Jung, Jae Pil
    • Journal of the Microelectronics and Packaging Society
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    • v.21 no.2
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    • pp.23-29
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    • 2014
  • Less power consumption, lower cost, smaller size and more functionality are the increasing demands for consumer electronic devices. The three dimensional(3-D) TSV packaging technology is the potential solution to meet this requirement because it can supply short vertical interconnects and high input/output(I/O) counts. Cu(Copper) has usually been chosen to fill the TSV because of its high conductivity, low cost and good compatibility with the multilayer interconnects process. However, the CTE mismatch and Cu ion drift under thermal stress can raise reliability issues. This study discribe the thermal stress reliability trend for successful implementation of 3-D packaging.

Thermo-Mechanical Reliability of TSV based 3D-IC (TSV 기반 3차원 소자의 열적-기계적 신뢰성)

  • Yoon, Taeshik;Kim, Taek-Soo
    • Journal of the Microelectronics and Packaging Society
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    • v.24 no.1
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    • pp.35-43
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    • 2017
  • The three-dimensional integrated circuit (3D-IC) is a general trend for the miniaturized and high-performance electronic devices. The through-silicon-via (TSV) is the advanced interconnection method to achieve 3D integration, which uses vertical metal via through silicon substrate. However, the TSV based 3D-IC undergoes severe thermo-mechanical stress due to the CTE (coefficient of thermal expansion) mismatch between via and silicon. The thermo-mechanical stress induces mechanical failure on silicon and silicon-via interface, which reduces the device reliability. In this paper, the thermo-mechanical reliability of TSV based 3D-IC is reviewed in terms of mechanical fracture, heat conduction, and material characteristic. Furthermore, the state of the art via-level and package-level design techniques are introduced to improve the reliability of TSV based 3D-IC.