电热固耦合作用下车载功率模块引脚焊点振动疲劳寿命研究

Research on Vibration Fatigue Lives of Pin Solder Joints on Vehicle⁃Mounted Power Module Under Electric⁃Thermal⁃Solid Coupling

本文对车载功率模块引脚焊点在器件功率损耗产生的热量和路面颠簸引起的随机振动共同影响下的可靠性进行了研究.建立多物理场有限元分析模型对引脚焊点进行电热固耦合疲劳寿命仿真,得到发热状态和常温状态下的焊点随机振动响应应力分布和振动疲劳损伤值.利用基于经验的Dirlik疲劳损伤模型和Miner线性损伤累积法则对两种状态的疲劳寿命进行了估算和对比分析.结果表明:在考虑电热固耦合作用下,局部约束刚度降低和焊点振动响应应力增大导致焊点振动疲劳寿命明显降低,但仍然满足规定的振动可靠性要求.结合满功率负载发热状态下的振动失效试验结果,验证了分析结果的准确性和装置设计的可靠性.

The reliability of pin solder joints on vehicle-mounted power module under the combined effects of heat generated by power loss and random vibration caused by road bump was explored.Fatigue life simulations of pin solder joints under electricthermal-solid coupling were performed using the multi-physics field finite element models.The stress distribution and fatigue damage of the random vibration response were obtained for both elevated and normal temperature conditions.Furthermore,theoretical fatigue lives were also predicted and contrasted using empirical-based Dirlik model and Miner linear cumulative damage rule.The results show that the vibration fatigue life of solder joints decreases significantly considering electric-thermalsolid coupling effect due to the decrease of local constraint rigidity and the increase of vibration stress of solder joints,nevertheless still meets the specified vibration requirement.Finally,the accuracy of analysis results and the reliability of structural design were verified through conducting the vibration failure tests under full-power heating condition.