热超声倒装键合换能系统多模态振动与有限元分析

研究了热超声倒装键合设备的核心执行机构——换能系统的动力学特性.利用激光多谱勒测振仪测试系统末端各方向的振动速度,发现系统以轴向振动为主,但受到其他非轴向振动的干扰.非轴向振动对芯片造成芯片倾斜、键合强度降低等负面影响.采用有限元方法对换能系统建模,仿真计算发现换能系统振动是各方向振动的耦合结果,且工作模态附近存在多种干扰模态.最后分析了系统多模态产生的根源并提出抑制方法.

Multiple Modal Vibration and FEM Analysis of Ultrasonic Transducer for Thermsonic Flip Chip Bonding

The dynamics of ultrasonic transducer for thermosonic flip chip bonding is investigated. Velocities of mark points on transducer and bonding tool, which represent different modal vibrations, are sampled by a laser Doppler vibrometer. The results show the axial vibration is dominant while it is disturbed by other non-axial components.It means that the ultrasonic transducer system vibrates complicatedly, which couples the axial and non-axial components simultaneously. The effect of non-axial vibration influences significantly the bonding quality such as chip tilting and poor bonding strength. The multiple vibrations of ultrasonic transducer is analyzed by finite element model. It is found that ultrasonic transducer vibrates in coupling resultant of all allowable modes being excited. The origin and corresponding control method for multiple vibrations is brought forward.