基于裂纹扩展的无铅焊点阻抗等效模型

An equivalent impedance model for lead-free solder joints based on crack propagation

以单个无铅焊点为研究对象,根据裂纹扩展及趋肤效应建立了无铅焊点的阻抗等效模型,给出了模型参数的计算方法,并用Matlab软件对模型进行了仿真。结果表明:随裂纹扩展,焊点阻抗经历了一个由缓慢变化到突变的过程,且信号频率越高,阻抗突变时间越早;在500 MHz信号作用下,当裂纹面积约为焊点横截面的75%时,焊点阻抗便发生突变,而直流电阻则在焊点临近断裂时才有较大的变化。

After a case study on single solder joint, an equivalent impedance model was established for lead-free solder joints based on the crack propagation and skin effect of the joint, and the way to calculate the parameters included in the model was introduced. Simulation was then performed using the Matlab software. The results show that with the crack propagation, the impedance of solder joints changes slowly first and then abruptly. And, the higher the signal frequency is, the earlier the abrupt change takes place. At a frequency of 500 MHz, the abrupt change of impedance occurs when the area of crack is about 75% of the cross section of solder joint; while the DC resistance only changes sharply right before the failure of solder joint.