High-frequency 1–3 piezoelectric composite planar phased-array underwater acoustic transducers: design, finite element simulation, fabrication and characterization

Abstract

High-frequency two-dimensional piezoelectric composite phased arrays require reliable element-level electrical interconnection to achieve precise phase and amplitude control; however, conventional embedded conductive structures and adhesive-based flexible circuits remain limited by insufficient electrical accessibility, mechanical reliability, and fabrication scalability. In this work, a robust flexible circuit welding interconnection strategy is proposed for high-frequency 1–3 piezoelectric composite planar phased array underwater acoustic transducers. The coupling vibration behavior between piezoelectric pillars and polymer matrices was systematically investigated using finite element simulation, revealing the influence of pillar width and ceramic/polymer volume ratio on resonance characteristics and parasitic mode suppression. Based on the optimized composite configuration, an 8 × 8 array transducer with individually addressable elements was fabricated by integrating dice-and-fill 1–3 piezoelectric composite with a flexible circuit through direct solder interconnection. The proposed architecture provides stable element-level electrical isolation while avoiding the interface reliability issues associated with conventional bonding methods. Experimental characterization demonstrates uniform resonance behavior among 64 array elements and improved electromechanical coupling and bandwidth compared with monolithic PZT ceramics. Furthermore, underwater acoustic measurements verify effective acoustic radiation near the designed operating frequency. This study provides a scalable interconnection approach for compact high-frequency piezoelectric composite phased arrays and provides a practical approach for structural optimization of composite-based underwater acoustic transducers.