The effect of oblique sub-dicing on acoustic performance

Piezoceramic-polymer composite materials are widely used as active materials for ultrasound arrays. The main advantages of composite are a high electromechanical conversion efficiency and low mechanical impedance. In a traditional production process, individual elements of a one-dimensional array are usually sub-diced into sub-elements to avoid spurious resonances and to increase the electromechanical coupling factor of the 2-2 composite array. In this study, we propose oblique subdicing to suppress the effect of spurious lateral resonances. A potential advantage of applying oblique sub-dicing in the array production process is a reduced number of sub-dices without compromising the frequency response. This could result in reduced production time and an increased ceramic-volume fraction. In this work, electrical impedance measurements on trapezoidal ceramic elements demonstrated the suppression of spurious lateral resonances, which was dependent on the angle of the oblique dicing kerf. Three dimensional FEM simulations confirmed these experimental findings. Subsequent FEM simulations showed the effect on the acoustic performance of oblique sub-kerfs on realistic arrays.