【摘要】 超声焊接作为一种固相连接技术，广泛用于功率半导体的封装工艺中。针对试验观测方式难以研究超声焊接复杂瞬态过程及其连接机理的难题，建立了一个“声-热-力”多场耦合的三维有限元模型来研究这一复杂动态过程，考虑了热和摩擦的双向耦合作用，在热软化的基础上引入了超声对材料的软化效应，并使用模拟得到的工件振幅来动态更新声软化系数，提高了有限元模型的准确性。基于该耦合模型，进一步探究了金属超声焊接过程中工件振幅传递、温度场分布以及塑性变形等复杂机械行为，并分析了振幅、压力等工艺参数对焊接过程的影响。结果表明，工件温度和塑性变形的模拟结果与实测数据吻合较好；超声振动能量在工件间传递存在衰减；工件焊接区域中心温度明显高于焊接边缘温度，但仍远低于材料熔化温度；热和声软化对工件塑性变形均有显著作用，其中声软化的贡献率约为38%。此外，超声焊接工艺参数对焊接过程有较大影响，对改善焊接质量具有潜在意义。更多还原

【Abstract】 As a solid-state bonding technology, ultrasonic welding is often used in the packaging process of power semiconductors. It is difficult to investigate the complex transient process and bonding mechanism of ultrasonic welding only by experimental observation. To explore this complex dynamic process, A three-dimensional finite element model of “acoustic-thermal-mechanical”multi-physics coupling is established. The bidirectional coupling of heat and friction is considered, and the softening effect of ultrasonic on the material is introduced on the basis of thermal softening. The acoustic softening coefficient is dynamically updated by the amplitudes of the two workpieces obtained from the simulation outputs, which improves the accuracy of the finite element simulation model. Based on the simulation model, the complex mechanical behavior of the workpieces is further investigated,including amplitude transfer, temperature distribution and plastic deformation. The influence of process parameters, namely amplitude and pressure, on the welding process is also analyzed. The result shows that the simulated results of temperature and plastic deformation of the workpieces are consistent with the experimental data. The ultrasonic vibration energy decays when the vibration is transferring between the workpieces. The temperature at the center of the welding area is significantly higher than that at the edge, but is still far lower than the melting point of the material. Both thermal and acoustic softening have significant effects on the plastic deformation of the workpieces, and the contribution ratio of acoustic softening to the deformation is about 38%. In addition, ultrasonic welding process parameters have great influence on the welding process, which has potential meaning for improving welding quality.更多还原