Progress towards the development of novel fabrication and assembly methods for the next generation of ultrasonic transducers

The development trends of ultrasonic devices dictate that frequencies increase, electrode element counts increase, and element pitch dimensions shrink. The high density of the small pitch electrode elements combined with the challenging geometry of the device design, and considerations of acoustic impedance and signal interference, mean that new assembly and packaging techniques are required to be developed to form the interconnection between the high frequency ultrasound (HFUS) arrays and external circuitry. Novel assembly methods using photolithography of new epoxy composite alumina/SU-8 and high density flexible circuits, precision dicing of lead zirconate titanate (PZT) material, flexible circuits and SU-8 resin, powder blasting for vias structuring, and conductive and adhesive films bonding are considered as a mass-scale production approach.