高温高电流密度下BGA焊点电迁移损伤

Electromigration Damage Analysis of BGA Solder Joint Under High Temperature and High Current Density

为了研究球栅陈列封装(ball grid array,BGA)焊点在高温、高电流密度条件下的电迁移损伤演化行为,基于COMSOL Multiphysics 5.5软件提出一种损伤记录方法来模拟电-热-力多物理场耦合的工况,分析电迁移空洞产生和扩展的过程.综合考虑了电子风力、温度梯度、应力梯度和原子浓度梯度4种原子扩散动力对原子迁移的作用.结果表明:电迁移过程中电子风力和原子浓度梯度对电迁移空洞的形成起着主要作用,随着损伤的积累,电流堆积因子不断提高,孔洞周围电子风力作用更加明显,相反,原子浓度梯度通量起到了抑制原子过度迁移的作用.环境温度会影响焊点原子扩散系数,较高的温度下原子扩散系数较大,当环境温度处于高低温循环条件时,应力梯度通量和电子风力通量成为原子迁移主要动力.

The electromigration damage evolution of BGA solder joints under high temperature and high current density condition was studied.Based on the COMSOL Multiphysics 5.5,a damage recording method was proposed to simulate the electro-thermal-mechanical multi-physics coupling and to analyze the generation and expansion of electromigration voids.The effects of four kinds of atoms diffusion force were comprehensively considered,including electron wind,temperature gradient,stress gradient and atomic concentration gradient.Results show that the electron wind force plays a major role in the formation of the electromigration voids,on the contrary,the atom gradient flux inhibits the excessive atom migration.The ambient temperature affects the atomic diffusion coefficient of the solder joint,and the atoms diffusion coefficient is larger at higher temperatures.When the ambient temperature is in the temperature cycle condition,the stress gradient flux and the electron wind flux become the main atoms migration force.