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An Analysis on the Thermal Shock Characteristics of Pb-free Solder Joints and UBM in Flip Chip Packages  

Shin, Ki-Hoon (서울산업대 기계공학과)
Kim, Hyoung-Tae (서울산업대 에너지환경전문대학원)
Jang, Dong-Young (서울산업대 산업정보시스템공학과)
Publication Information
Transactions of the Korean Society of Machine Tool Engineers / v.16, no.5, 2007 , pp. 134-139 More about this Journal
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
Flip Chip; Pb-free Solder Joint; UBM; Thermal Shock;
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Times Cited By KSCI : 1  (Citation Analysis)
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