Study of Process-Induced Warpage and Paddle-Shift Phenomena in IC Packaging

• Main Authors: Shiang-Yu Teng, 鄧湘榆
• Other Authors: S. J. Hwang
• Format: Others
• Language: zh-TW
• Published: 2007
• Online Access: http://ndltd.ncl.edu.tw/handle/24945476665771444778

博士 === 國立成功大學 === 機械工程學系碩博士班 === 95 === Warpage problems play an important role in IC encapsulation processes. Previous researchers had focused on warpage analyses with temperature changes between constituent materials and neglected the cure shrinkage effects. However, more and more studies indicate that estimation of warpage according to CTE (Coefficient of Thermal Expansion) was not able to predict the amount of warpage in IC packaging. The EMC properties were obtained by various techniques: degree of cure by differential scanning calorimeter (DSC), modulus by P-V-T-C testing machine. These experimental data were used to formulate P-V-T-C equation. The purpose of this study was to find out the method of warpage estimation due to P-V-T-C equation of EMC. In this study, mold filling analyses were conducted to predict cure content within models. Predicted warpage values were compared with experimental and numerical results. With thorough investigation, the result showed that cure shrinkage of epoxy was a significant parameter for IC packaging warpage estimation. The P-V-T-C equation was successfully implemented to verify that warpage was governed by thermal shrinkage and cure shrinkage. A methodology for computational modeling and prediction of paddle shift was also presented in this thesis. The methodology was based on modeling the flow of the polymer melt around the leadframe and paddle during the filling process, and extracting the pressure loading induced by the flow around the paddle. The pressure loading at different times during the filling stage was then applied to a three-dimensional, static, structural analysis module to determine the corresponding paddle deflections at those times. By comparing the experimental results and simulation results, it was shown that the analytic simulation with decoupled flow and structure analyses could achieve good accurate and efficient prediction of paddle shift phenomena.