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基于有限元法,结合子模型技术对倒装芯片球栅阵列封装(FCBGA)进行电-热-结构耦合分析,获得关键焊点的电流密度分布、温度分布和应力分布,采用原子通量散度法(AFD)和原子密度积分法(ADI)对关键焊点的电迁移(EM)特性及影响因素进行研究。结合焊点电迁移失效的SEM图,发现综合考虑电子风力、应力梯度、温度梯度以及原子密度梯度四种电迁移驱动机制的原子密度积分法能比较准确地预测焊点的电迁移失效位置,原子密度梯度(化学势)通常会延缓电迁移现象。
Based on the finite element method and coupled with submodeling technique, the current-density distribution, temperature distribution and stress distribution of the key solder joints were obtained by the coupled analysis of the flip-chip ball grid array package (FCBGA) (AFD) and atomic density integral method (ADI) were used to study the electromigration (EM) characteristics and influencing factors of critical solder joints. Combined with the SEM images of the electromigration failure of the solder joints, it is found that the atomic density integral method of the four electromigration driving mechanisms considering the electron wind force, the stress gradient, the temperature gradient and the atomic density gradient can predict the electromigration failure location of the solder joint more accurately. Density gradients (chemical potentials) usually delay the electromigration phenomenon.