Ultrasonic measurements of surface defects on flexible circuits using high-frequency focused polymer transducers

Abstract

High frequency transducers made from a layer-by-layer deposition method are\ninvestigated\nas \ntransducers for ultrasonic imaging. Prototypes of adhesive-free transducers\nwith four active \nelements \nwere made on a high performance PEI\n(Polyetherimide)\nsubstrate\nwith\nprecision \nmilled \nspherical cavities used to produce focused ultrasonic beams.\nThe \ntransducer \nprototypes \nwere \ncharacterized using a pulse\n-\necho experimental setup in water tank using glass plate as \na \nreflector. Then, \nit was\nused \nin \na\n3D \nultrasonic scanning tank, to \nproduce high\n-\nresolution \nultrasonic images \nof \nflexible electronic circuits \nwith the aim\nto detect defects in the outermost \ncover layer.