No abstract

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.

No abstract

The improvement on an existing powder blasting machine is presented and characterised in this paper. The original prototype suffered from irregular powder clogging during real time utilisation, especially with very fine particles. Moreover, the fluctuations of the flow of particle generated were not ideal for micro-machining purposes. We demonstrate that the re-engineering of the original reservoir used with freshly dried powder brings reliability and more consistency in the powder flow rate. This improvement is easy to implement in the original design and does not need to re-engineer the entire machine. For this study, very fine powder with average particle diameter of 9 fJlli was used.