High-speed defect detection of printed circuit board based on eddy-current testing method

Eddy-current testing (ECT) technique, which is one of non-destructive evaluation, is applied to detect defect on printed circuit board (PCB). The ECT probe consists of a meander coil as an exciting coil and a giant magneto-resistance (GMR) sensor as a magnetic sensor. The ECT signal archived from a GMR sensor composes of many unwanted signals. Therefore, a defect detection system eliminates noise from measured ECT signal. If noise elimination requires many signal data, the probe necessary to move slowly in order to measure many signal data. Required signal data size depends on noise tolerance of defect detection. These mean that noise elimination is important factor in realizing high-speed defect detection system. We tried to eliminate noise in the time space, but it is difficult to remove the noise depending on the surface condition of PCB. In this report, we propose a defect detection method which eliminates noise not only in the time domain but also in the space domain. On a result, the method eliminates noise clearly by using smaller signal data and gives high-speed inspection of detect on PCB. © 2014 The Institute of Electrical Engineers of Japan.