热超声键合换能系统接触界面非线性振动研究

Research on Nonlinear Vibration of Contact Interface in Thermosonic Bonding Transducer System

为了减小热超声键合换能系统的振动稳定性、提高键合强度,从超声波在热超声键合换能系统中的传播出发,建立了超声波在接触界面处传播的微观模型。研究表明,当静应力较小时,输出的超声波不完整,材料内部质点的有效振动较小;当静应力逐渐增大时,材料进入弹性变形阶段,输出的超声波波形与输入的超声波的波形一致,材料内部质点的有效振动最大;当静应力太大时,材料进入塑性变形区域,材料内部质点的有效振动减小。通过在芯片倒装键合实验台上实验,测量在不同压电陶瓷片预紧力下,变幅杆的振动速度和芯片的键合强度,证明了所提出模型的正确性。

In order to reduce nonlinear of ultrasonic transducer system and increase bond strength, ultrasonic propagation at contact interface in thermosonic bonding system was analyzed. And the micromechanical model of ultrasonic propagation at contact interface was established. It reveals that when static stress is small, waveform of output ultrasonic is imperfect, and particle vibration displacement of material is small; when the static stress increases, the materials turn into elastic phase, and the vibration of particle is large; when the static stress is too large, the materials turn into plastic phase, and the vibration of particle is small. The tests are carried out on flip chip bonding tester. The velocity of horn and bond strength are measured at different pre-tighten force of piezoelectric ceramic. It is proved that the proposed model is right.