Analysis of the structure of printed circuit boards by means of the eddy current technique

This paper proposes an innovative application of the eddy current testing (EC) technique for printed circuit boards (PCB) inspection. For this purpose, a unique probe has been designed and fabricated. The probe is composed of a meander-exciting coil and a solenoid pick-np coil. The probe can detect various defects on the conductors; of PCBs, such as cracks, partial declines and chipped defects. The construction of the probe, the principles of detection and samples from scanning are presented A strong relationship between the amplitude and the phase of the output signal had been observed. This relationship allows a new approach to the analysis of signals obtained combining the amplitude and the phase for a new filtering method. Data from the phase characteristic can be used to set thresholds in the amplitude's filtering process. Thereby: signals coming from soldering points and defects can be separated Experimental data have confirmed efficiency of this inspection process. Application of the EC technique may be extended to the inspection of multi-layer PCBs in the future.