焊点形体与高度对热疲劳寿命的影响

Discussion for Effects of Solder Joint Shape and Height on Thermal Fatigue Lifetime

探讨了焊点形体与高度对热疲劳寿命的影响,采用加速温度循环和粘附试验,评定焊点疲劳寿命。使用扫描电子显微镜(SEM)、能量色散X射线光谱仪(EDX)、扫描声学显微镜(无损评价)和光学显微镜,检查焊点完整性,并探测加速疲劳试验之前及期间的裂纹和其他缺陷。加速温度循环试验清楚地表明,焊点疲劳失效过程包括三个阶段:裂纹萌生、裂纹传播和彻底失效。试验结果表明,沙漏形体和大支座高度都可提高焊点疲劳寿命,支座高度为更有效因素。试验数据说明,焊点形体是影响裂纹萌生时间的主要因素,而支座高度是影响裂纹传播时间的关键因素。

In this paper, the effects of solder joint shape and height on thermal fatigue lifetime are studied. Solder joint fatigue lifetime was evaluated using accelerated temperature cycling and adhesion test. Scanning electron microscopy （SEM）, energy dispersive x-ray analysis （EDX）, scanning acoustic microscopy （nondestructive evaluation） and optical microscopy were utilized to examine the integrity of the joint and to detect cracks and other defects before and during accelerated fatigue tests. Our accelerated temperature cycling test clearly shows that solder joint fatigue failure process consists of three phases： crack initiation, crack propagation and catastrophic failure. Experimental results indicated that both hourglass shape and great standoff height could improve solder joint fatigue lifetime, with standoff height being the more effective factor. Experimental data suggested that shape is the dominant factor affecting crack initiation time while standoff height is the major factor influencing crack propagation time.