Bare PCB Inspection By Mean Of ECT Technique With Spin-Valve GMR Sensor

The high-sensitive micro eddy-current testing (ECT) probe composed of planar meander coil as an exciter and spin-valve giant magneto-resistance (SV-GMR) sensor as a magnetic sensor for bare printed circuit board (PCB) inspection is proposed in this paper. The high-sensitive micro ECT probe detects the magnetic field distribution on the bare PCB and the image processing technique analyzes output signal achieved from the ECT probe to exhibit and to identify the defects occurred on the PCB conductor. The inspection results of the bare PCB model show that the proposed ECT probe with the image processing technique can be applied to bare PCB inspection. Furthermore, the signal variations are investigated to prove the possibility of applying the proposed ECT probe to inspect the high-density PCB that PCB conductor width and gap are less than 100 μm....