Q. Zhang, Y. Joshi and A. Dasgupta
CALCE Electronic Products and Systems Center
University of Maryland
College Park, MD 20742
A nonlinear finite element model was used to analyze the thermally induced viscoplastic deformation and low cycle fatigue behavior of flip- chip on ceramic (FCOC) solder joints. An energy- partitioning damage model was employed to assess the durability of the package. The effects of solder volume, number of interconnects, interconnection density, and dummy bumps on the viscoplastic deformation and durability of the package were studied by changing the geometry of the package. The effects of different dwell times, temperature range, mean temperature and ramp rate on the viscoplastic deformation and durability of the package were also studied by applying different temperature cycles to the package. The modeling results show that four corners of the critical solder joints suffer large viscoplastic strains and generally, maximum strains occur at the bottom right corner of the critical joint. Solder volume and interconnection density are the important geometric factors for durability of FCOC interconnects. Temperature range, dwell time and ramp rate of thermal loads have large effects on the durability of the package. The modeling results provide useful guidance to design FCOC packages.
Key words: Flip-Chip on Ceramic, Viscoplasticity, CTE, Solder Joint Reliability, and Finite Element Analysis.
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