On the Effects of Package on the PMUTs Performances-Multiphysics Model and Frequency Analyses

Area of Science:

• Multiphysics numerical modeling
• Finite Element Method (FEM)
• Ultrasonic transducers

Background:

• Piezoelectric micromachined ultrasonic transducers (PMUTs) are crucial for various applications.
• Fabrication-induced residual stresses can significantly impact PMUT performance.
• Accurate modeling is essential for optimizing PMUT design and functionality.

Purpose of the Study:

• To develop a comprehensive 3D multiphysics numerical model for air-coupled array PMUTs.
• To investigate the influence of residual stresses and packaging on PMUT behavior.
• To provide design guidelines for improved acoustic transmission.

Main Methods:

• Finite Element Method (FEM) for a fully 3D numerical model.
• Incorporation of fabrication-induced residual stresses.
• Modeling of electro-mechanical coupling, acoustic-structure interaction, and pressure acoustics.
• Simulation of a 4x4 array PMUT configuration with protective packaging.

Main Results:

• The model accurately captures the geometrically non-linear initial diaphragm deformation due to residual stresses.
• A significant shift in the fundamental frequency was observed and predicted.
• Experimental validation confirmed the model's accuracy for static and dynamic responses.
• Analysis of packaging configurations and holes provided insights into acoustic transmission (SPL and propagation).

Conclusions:

• The developed 3D FEM model is a valuable tool for analyzing array PMUTs.
• Residual stresses play a critical role in PMUT initial configuration and frequency response.
• The study offers practical design guidelines for optimizing PMUT performance, particularly concerning acoustic transmission.
• This work contributes to the advancement of ultrasonic transducer technology.