无铅焊点的电阻应变温度迟滞回线特性

在焊点热可靠性研究过程中,发现无铅焊点在313.15～398.15K循环热载荷条件下电阻应变与温度存在滞后效应,以力学分析方法对该效应的迟滞回线进行了分析讨论。结果表明:塑性电阻应变是引起迟滞回线变化的主要原因;稳定期内一个循环的最大塑性电阻应变量是0.00158,电阻应变滞后于温度变化18.31s;高温迟滞回线变化较低温更明显,二者相差0.0036749,反映了高温下焊点内部损伤程度更快。随着循环次数的增多,迟滞回线从不稳定趋向稳定,最后趋向不闭合,且斜率降低。

Resistance strain and temperature hysteresis loops properties of lead free solder joint

In the investigative process of heat reliability of lead free solder joint, hysteresis loops were discovered between resistance strain and temperature of lead free solder joint under the condition of circular load at 313.15～398.15 K ℃. The characteristics of hysteresis loops were analyzed and discussed by the way of mechanical anylysis. The results show that the plastic resistance strain is the main reason for inducing the hysteresis loops, the maximum plastic resistance strain is 0.001 58 at one cycle in stabilization period and resistance strain is 18.31 s latter than temperature. The change of hysteresis loops under high temperature is faster than that under low temperature and the both gap is 0.003 674 9. The loops change from unsteady to steady and finally to un-closed, and its slope become lower with cycle times increasing.