Application of ECT technique for inspection of bare PCB

The detection of imperfections (such as disconnections, chipping cracks, nonuniformity in thickness and short-circuits) on the traces of a bare printed circuit board (PCB) using a new high-sensitive eddy-current testing (ECT) probe is reported in this paper. The ECT technique is composed of a planar meander type exciting coil and a new multiple solenoid sensing coil. An image processing method is used to analyze the results. This paper discusses the structure of the new probe and the characteristics of the measurement technique to inspect high-density PCBs with narrow conductor-width. The possibility of detecting micro-metal balls is explored.