芯片键合纵弯复合超声换能器的设计与试验

为了解决当前采用一维纵向超声加载模式进行芯片键合时造成结合面不充分的问题，设计纵弯复合超声能量加载模式的压电超声换能器，实现轴向纵振和水平弯振复合的超声振动代替传统单一的轴向振动. 采用ANSYS软件，对换能器有限元模型进行模态分析和谐响应分析，得到换能器纵振和弯振模态的谐振频率及振型. 通过调节换能器结构尺寸，实现纵振与弯振模态的简并. 采用阻抗分析仪对样机的频率和阻抗进行测试，使用激光多普勒测振仪测试换能器的纵振与弯振幅值，测试结果与有限元仿真计算结果一致，发现纵向与弯曲振幅均随着驱动电压的增加呈近似线性上升趋势, 证明设计的压电换能器实现了纵弯复合振动.

Design and experiment of longitudinal-flexural composite ultrasonic transducer for chip bonding

A piezoelectric transducer with longitudinal-flexural composite ultrasonic mode was developed in order to solve the problem that the ultrasonic energy with one-dimensional longitudinal mode causes insufficient bonding area during chip bonding. The transducer can generate composite ultrasonic vibration to replace the conventional longitudinal vibration. The finite element simulation by ANSYS Workbench was employed to conduct the modal analysis and harmonic response analysis of transducer. The resonant frequency and mode shape of the longitudinal and flexural modes were obtained. The longitudinal and the flexural vibration modes were degenerated by adjusting the size of the transducer structure. The frequency and impedance testing of the prototype were conducted by impedance analyzer. The longitudinal and flexural amplitude of the transducer were measured by laser Doppler vibrometer. The experimental results accorded with the finite element calculation. The amplitude of the longitudinal and flexural vibration showed an upward tendency with the increasing of driving voltage. Results prove that the designed transducer can achieve the longitudinal-flexural composite vibration.