Manufacturing technologies for ultrasonic transducers in a broad frequency range
1-3 piezocomposite | ultrasonic transducer | piezoelectric fiber | piezofiber composite | piezoelectric thick film | soft mold process
According to the application field, working frequency of ultrasonic transducers needs to be tailored to a certain value. Low frequency ultrasonic transducers with working frequencies of 1 kHz to 1 MHz are especially interesting for sonar applications, whereas high frequency ultrasonic transducers with working frequencies higher than 15 MHz are favorable for high-resolution imaging in biomedical and non-destructive evaluation. Conventional non-destructive testing devices and clinical ultrasound imaging systems are typically operated at frequencies between 1 MHz and 10 MHz. Depending on the operational scenario, thickness, layout, and inner structure of the ultrasonic transducer has to be customized. We here report on different manufacturing technologies for ultrasonic transducers in a broad frequency range. 1-3 piezocomposites based on piezoceramic fibers can be fabricated in almost every thickness allowing for transducer frequencies between 40 kHz and 8 MHz. The soft mold process enables the fabrication of high frequency ultrasonic transducers with potential frequencies of 5 MHz up to 40 MHz. Highly integrated ultrasonic transducers can be pre-pared by screen-printing a sequence of electrode, piezoceramic, and isolation layers on microelectronic substrates. With that, patterned ultrasonic transducers with working frequencies between 5 MHz and 30 MHz are possible.