Design And Dynamic Characteristics Of A High-frequency Ultrasonic Transducer With A Dual-branch Parallel Structur

Thermal ultrasonic bonding is a representative technology for solid-state joining,which can achieve reliable electrical connections between the metal leads and pads on the substrate by combining ultrasonic,force,and heat.The ultrasonic transducer is one of the key components of the thermosonic bonding equipment,and it is an important carrier that converts electrical energy into mechanical vibration required for bonding.Using multiple single-branch ultrasonic transducers to constitute a composite structure transducer has a good application prospect in the electrical connections for the large wire diameters,multiple wires,dissimilar metals(such as aluminum/copper)bonding,and soft material substrates,like connections of IGBT modules,LEDs,large-capacity lithium battery packs,and solar panel components.This subject closely combines the key scientific issues that need to be solved in the practical application of the composite structure high-frequency ultrasonic transducer.Based on our previous researches,a flexible mounting clamp-based dual-branch parallel composite structure highfrequency ultrasonic transducer was proposed,and in-depth research on the dynamics optimization design theory and method of this type of transducer was carried out.(1)A flexible mounting clamp-based dual-branch composite structure highfrequency ultrasonic transducer is proposed.The transducer is composed of two singlebranch high-frequency ultrasonic transducers constructed into a parallel composite structure through a Y-shaped connector.Based on the theory of two-branch simple harmonic signal synthesis,the working characteristics of this type of transducers in the coupling mode are analyzed in detail,and the general law and construction method of the transducer elliptical trajectory working mode and rectangular trajectory working mode are summarized.(2)To establish a design method for the dual-branch parallel composite structurebased transducer under a coupling mode,the wave equation of the elastic rod,the piezoelectric structure equation,the theory of Timoshenko beam,the modular design theory,the transfer matrix method,and the electromechanical equivalent design method were comprehensively utilized.The longitudinal-bending vibration models of the elastic rod unit,the piezoelectric ceramic unit,and the coupling connector unit were established.The interface connection conditions between different structural units were analyzed,and the electromechanical coupling dynamics model of the dual-branch parallel composite structure high-frequency ultrasonic transducer is established.(3)By the mechanical and electrical boundary conditions,the initial size parameters of the key structure of the branch transducer are calculated by using the graphic method.To further investigate the modal characteristics of the transducer near the working frequency and realize multi-modal suppression and modal separation,the finite element modal analysis and sensitivity analysis methods are used comprehensively,and the influence of key geometric parameters of the transducer on the modal characteristics of the transducer is studied.Then through the mass perturbation method to complete the size optimization of the dual-branch parallel structure high-frequency ultrasonic transducer;after determining the displacement node of the branch transducer,a flexible clamp is configured for the composite structure transducer,and comprehensively evaluate the effectiveness of the clamping flange under the finite element environment.(4)To verify the effectiveness of the proposed design method of the dual-branch parallel composite structure high-frequency ultrasonic transducer,and test the working performance of the transducer,independently developed the excitation signal generation,power amplification,impedance characteristic monitoring,and highfrequency signal synchronous acquisition systems,built a test platform for electrical characteristics and vibration characteristics,and made a prototype of a dual-branch parallel composite structure high-frequency ultrasonic transducer.On this basis,a series of electrical and vibration characteristics test experiments have been carried out.The experimental results show that the designed composite structure transducer has good working performance,and the established composite structure transducer design method is feasible and effective.It has laid a solid foundation for follow-up research such as the development and practical application of the control system of the composite structure transducer.