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测量了有无芯下填料 B型和 D型两种倒扣芯片连接器件的焊点温度循环寿命 ,运用超声显微镜 (C- SAM)和扫描电镜 (SEM)观察了焊点微结构粗化和裂纹扩展 ,并采用三维有限元模拟方法分析了焊点在温度循环条件下的应力应变行为 .结合实验和模拟结果 ,建立了预估焊点疲劳寿命的 Coffin- Manson半经验方程 ,得到方程中的系数C=5 .5 4 ,β=- 1.38.模拟给出的焊点中剪切应变的轴向分布与实验得到的焊点在温度循环过程中的微结构粗化一致 .填充芯下填料后的倒扣芯片连接由于胶的机械耦合作用 ,降低了焊点的剪切变形 ,但热失配引起的器件整体弯曲增强 ,芯片的界面应力增大 .模拟结果与实验观察完全一致
The solder joint temperature cycle life was measured with or without underfill type B and D flip chip connections. Microstructure roughness and cracks of the solder joints were observed by using a C-SAM and a scanning electron microscope (SEM) And the stress-strain behavior of the solder joint under temperature cycling was analyzed by using the three-dimensional finite element method.Coupin-Manson semi-empirical equation for estimating the fatigue life of the solder joint was established by combining the experimental results and the simulation results, and the coefficients in the equation C = 5.54, β = -1.38. The axial distribution of shear strain in the solder joint simulated by the simulation is consistent with the microstructure coarsening of the experimental solder joint during the temperature cycling. Inverted chip connection reduces the shear deformation of the solder joint due to the mechanical coupling of the glue, but the overall bending of the device caused by thermal mismatch increases and the interface stress of the chip increases. The simulation results are in good agreement with the experimental observations