Transactions of the Korean Society of Machine Tool Engineers (한국공작기계학회논문집)

The Korean Society of Manufacturing Technology Engineers (한국생산제조학회)
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An Analysis on the Thermal Shock Characteristics of Pb-free Solder Joints and UBM in Flip Chip Packages

플립칩 패키지에서 무연 솔더 조인트 및 UBM의 열충격 특성 해석

  • 신기훈 (서울산업대 기계공학과) ;
  • 김형태 (서울산업대 에너지환경전문대학원) ;
  • 장동영 (서울산업대 산업정보시스템공학과)
  • Published : 2007.10.15
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Abstract

This paper presents a computer-based analysis on the thermal shock characteristics of Pb-free solder joints and UBM in flip chip assemblies. Among four types of popular UBM systems, TiW/Cu system with 95.5Sn-3.9Ag-0.6Cu solder joints was chosen for simulation. A simple 3D finite element model was first created only including silicon die, mixture between underfill and solder joints, and substrate. The displacements due to CTE mismatch between silicon die and substrate was then obtained through FE analysis. Finally, the obtained displacements were applied as mechanical loads to the whole 2D FE model and the characteristics of flip chip assemblies were analyzed. In addition, based on the hyperbolic sine law, the accumulated creep strain of Pb-free solder joints was calculated to predict the fatigue life of flip chip assemblies under thermal shock environments. The proposed method for fatigue life prediction will be evaluated through the cross check of the test results in the future work.

Keywords

References

  1. Nah, J. W., Kim, J. H., Lee, H. M. and Paik, K. W., 2004, 'Electromigraion in Flip Chip Solder Bump of 97PB-3Sn/37Pb-63Sn Combination Structure,' Acta Materialia, Vol. 52, pp. 129-136 https://doi.org/10.1016/j.actamat.2003.08.035
  2. Jang, S. Y., Wolf, J, Kwon, W. S. and Paik, K. W., 2002, 'UBM(Under Bump Metallization) Study for Pb-free Electroplating Bumping: Interface Reaction and Electromigration,' 2002 Electronic Components and Technology Conference
  3. Shin, K. H. and Chung, S. K., 2006, 'FEA-based Design and Fabrication of Functionally Graded Materials,' Key Engineering Materials, Vol. 326-328, pp. 1681-1684
  4. Lau, J. and Liu, K., 2004, 'Global Trends in Lead-free Soldering-Part I and II,' Advanced Packaging
  5. Shed, A., 2004, 'Accumulated Creep Strain and Energy Density based Thermal Fatigue Life Prediction Models for SnAgCu Solder Joint,' 54th ECTC, Las Vegas, Nevada, USA, pp. 737-746
  6. Shed, A., 2001, 'Predicting Solder Joint Reliability for Thermal, Power, and Bend Cycle within 25% Accuracy,' 2001 Electronic Components and Technology Conference, pp. 255-263
  7. Hossain, M. and Agonafer, D., 2004, 'Strain based Approach for Predicting the Solder Joint Fatigue Life with the Addition of Intermetallic Compound using Finite Element Modeling,' 2004 International Society Conference on Thermal Phenomena, pp. 358-367
  8. Darveaux, R., 1997, 'Solder Joint Fatigue Life Model, in Design and Reliability of Solders and Solder Interconnections,' Miner. Meta. Mater. Soc., pp. 213-218
  9. Kim, C. H, Hong, J. S. and Han, G. Y., 2006, 'Performance Advancement of Evaluation Algorithm for Inner Defects in Semiconductor Packages,' Transactions of KSMTE, Vol. 15, No. 6, pp. 82-87