通孔元件焊点的抗热疲劳性能预测 Ⅱ.焊点内部力学响应特征的数值模拟

PREDICTION ON RESPONSE TO THE THERMAL FATIGUE OF THROUGH-HOLE SOLDER JOINT II. Numerical Simmulation of Mechanical Response Characteristics of Inner Solder Joint

通过建立可靠性分析的力学模型,对温度循环载荷下通孔焊点内部应力应变场的分布特征进行了有限元数值模拟.结果表明,焊接方式的不同造成焊点形态的差异,进而应力应变的分布也不同;再流焊点的应力应变集中在钎料体及镀铜管处,而波峰焊点中线路板与镀铜层接触的拐角处是高应力集中区,这些位置容易引起裂纹产生和扩展.在热载荷过程中,应力-应变场的等值分布呈现出与温度历史相关的动态特性.

Based on the creation of mechanical models for prediction of the reliability of through-hole solder joints, the finite element numerical simulation was used to attain the feature of stress-strain distribution in the solder joints under thermal loading. The results show that different soldering processes result in different solder joint shapes, which leads to different stress-strain distributions. To the reflow soldered joints, stress-strain concentration is found in the solder body and the plated though hole (PTH) barrel; and to the wave soldered joints, stress concentration is detected at the corner of PCB/PTH barrel interface. Cracks are prone to initiate and propagate in the areas mentioned above. Furthermore, the stress-strain distribution in the solder joints has a dynamic feature related to temperature history during the temperature cycling.