Design Methodology of High Frequency Ultrasonic Transducer for Wire Bonding

A methodology is put forward for the design of high frequency ultrasonic transducer for wire bonding, which is based on the theory of the ultrasonic transducer, finite element method (FEM) and impedance analysis techniques. The axial vibration equation of the bar with varied section, piezoelectric equation and mechanical boundary conditions are used to conceive and design the transducer. Using the FEM, the piezoelectric converter and the ultrasonic horn are optimized respectively based the dynamic analysis, and the optimization model of the transducer is achieved finally. The mode and harmonic response analysis of the piezoelectric converter, ultrasonic horn and the transducer is clearly identified and carefully analyzed. And the influence of each feature of the ultrasonic transducer, such as the geometry, preloaded bolt mounting torque and the flange placement, to the mode scattering and transducer end response is discussed thoroughly. In order to research on the vibration characteristic of the transducer accurately, the piezoelectric element solid5 is used to define the piezoelectric ceramics. The piezoelectric property of the piezoelectric ceramics could be defined through the dielectric constant matrix, piezoelectric constant matrix and elasticity constant matrix. And the element PRETS179 is used to simulate the preload of the bolt. The prototyped transducer is tested through the impedance analysis, which proves the resemblance with the theory and FEM analysis.