Large aspect ratio microscale 1–3 piezoelectric arrays prepared by soft mold combined with UV curing

Abstract

1-3 piezoelectric composites, as materials with integrated structural/functional characteristics, are typically used to manufacture ultrasonic transducers. As a core sensitive element, the structural dimensions as well as the molding quality of the 1–3 piezoelectric array, will directly affect the transducer's operating performance. In this paper, an improved soft mold process is proposed to prepare lead zirconate titanate (PZT) microscale 1–3 piezoelectric arrays by a soft mold combined with UV curing process. Firstly, the rheological behavior of PZT ceramic suspension and the preparation process of polydimethylsiloxane (PDMS) soft mold were studied. The surface contact angle of the Si master mold modified by trimethylchlorosilane (TMCS) was significantly increased, facilitating the peeling of the PDMS soft mold from the Si master mold surface, thus improving the surface quality of the PDMS soft mold. Then, the sintering process, microstructure, and electrical properties of microscale 1–3 piezoelectric arrays were systematically investigated. The perpendicularity and integrity of the piezoelectric arrays were improved by an optimized sintering process, and the arrays had micropillar diameters as small as 8 μm and aspect ratios over 7.5. The electrical properties of the piezoelectric composites with thicknesses of 55 μm and 42 μm were analyzed to obtain their resonant frequencies fs of 33.8 MHz and 41.3 MHz, respectively. The developed novel soft mold process can realize the preparation of microscale 1–3 piezoelectric arrays with fine structure and large aspect ratios, which are expected to fabricate high-frequency ultrasonic transducers.