Effect of mechanical compliance of mounting clamp on electrical properties and vibration response of high-frequency piezoelectric ultrasonic transducer for microelectronic packaging and interconnection

To figure out how the mechanical compliance of the mounting clamp impacts the performance of the high-frequency piezoelectric ultrasonic transducer, several flexible hinge-based mounting clamps with different compliance were designed, then a series of experiments and analyses were performed. The electrical characteristic analysis results show both the electromechanical coupling coefficient and the quality factor of the transducer increase with the increment in the mechanical compliance of the clamp, in the meanwhile, the frequency shift between the actual and nominal resonance frequencies of the transducer is greatly reduced. Under the same excitation condition, with the mechanical compliance of the clamp increasing by 2.2 times, the longitudinal and lateral vibration outputs of the transducer have increased by 39.8% and 44.4%, respectively, indicating more ultrasonic energy is transferred to the output tip of the transducer, which also enlarges the action area of the ultrasonic energy. The power spectrum of the longitudinal vibration signal reveals that the energy distributed at the fundamental has increased by 3.96 times, while that of the second- or third-harmonics exhibits a significant decline, manifesting the promotion of the compliance can improve the purity of the fundamental vibration, and lower the modal coupling level.