基于电阻应变临界点的无铅焊点失效分析

Failure analysis of lead-free solder joints based on resistance strain critical point

利用特制的焊点在线测试系统,测试了不同载荷条件下单个无铅焊点的电阻应变曲线,推导出电阻应变和损伤量之间的定量关系式,分析了焊点失效特性。结果表明:无铅焊点电阻应变曲线包括线性变化区和指数变化区;两个区域临界点处的电阻应变值为0.05左右,临界点至失效的时间约占焊点寿命的20.00%～30.00%;热循环条件下,40℃的电阻应变曲线临界点滞后于125℃的临界点,滞后时间约占焊点寿命的7.50%。

The failure properties of single lead-free solder joint were explored with resistance strain curve under different load conditions by a special-made solder joint on line electronic testing system, and the quantitate relationship formule between resistance strain and damage was deduced. The results show that resistance strain curves include a long time linear change period and a short time exponential change period. The resistance strain value at the critical point of the two periods is about 0.05, and the time of the critical point to failure is in 20.00% to 30.00% of solder joint life. In thermal cycle, the critical point of 40 ℃ resistance strain curve lags that of 125℃, and the lag time is about 7.50% of the solder joint life.