Application of ultrasonic iterative deconvolution technique to the case of internal defect detection in multi-layered PCB components

摘要

Possibilities of improvement in detection and characterisation accuracy concerning internal defects in multi-layered printed circuit boards (PCB) and electronic components by applying the ultrasonic immersion technique have been investigated. The experiments have been carried out on a real PCB with a mounted defective microchip. Defect-free and defective high-voltage semiconductor components have also been investigated. The investigations have been performed using the acoustic microscope produced by Ultrasonic Science Ltd and ultrasonic measurement system developed at the Ultrasound Institute of Kaunas University of Technology. The novel signal processing method based on the adaptive numerical model of ultrasonic wave propagation through a multi-layered electronic component and respective selection of signal components in time and frequency domains have been proposed. Two different signal processing techniques have been used to increase the contrast of defective regions and so improve reliability of ultrasonic inspection.