The distance between adjacent circuits of high density printed circuit board (PCB) is reduced gradually.The particles of different components have different permittivity,which changes the electric field distribution that induces electrochemical migration (ECM) failure.In this paper,by the finite element method,the electric field distribution between the paralleled circuits with potential bias on PCB contaminated by dust is analyzed.The mechanism of the dielectric constant and the amount of charges of dust particles on the electric field distribution is studied.The effect of electric field distribution on dendrite growth path is predicted.Finally,by the electrochemical migration simulation experiments,the relation between the electric field distribution and dendrite growth path is verified.The time to failure of ECM caused by the change of electric field is also discussed.%随着印制电路板上相邻导线之间间距不断减小,潮湿环境下的尘土颗粒改变了诱发电化学迁移失效的电场分布.本文采用有限元法对尘土污染的带电电路板上平行导线间的电场分布进行仿真分析,得出尘土介电常数和带电量对电场分布的作用机理,预测电场分布的改变对电化学迁移晶枝生长路径的影响,最后模拟实验验证晶枝生长的路径与电场分布的关系,并讨论尘土对电化学迁移失效时间的影响.
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