Bare PCB Inspection System With SV-GMR Sensor Eddy-Current Testing Probe

This paper describes bare printed circuit board (PCB) inspection based on eddy-current testing (ECT) technique with high scanning speed. A high-frequency ECT probe composed of a meander coil as an exciting coil and the spin-valve giant magnetoresistance (SV-GMR) sensor was fabricated and is proposed. The ECT probe was designed based on crack inspection over flat surface, especially suitable for microdefect detection on high-density bare PCB. The ECT signal detected by the SV-GMR sensor was acquired by high-speed A/D converter for applying the signal processing based on digital technique. Harmonic analysis based on Fourier transform was used to analyze the ECT signal at fundamental frequency in order to increase inspection speed and this technique allowed the ECT probe to scan bare PCB, with high sampling frequency and with high-spatial resolution inspection. Experimental results verified the possibility and the performance of the proposed PCB inspection system based on ECT technique