Application of eddy-current testing technique for high-density double-layer printed circuit board inspection

Inspection of high-density double-layer printed circuit board (PCB) should examine both layers to obtain an accurate inspection. Eddy-current testing (ECT) technique is successful for defect inspection on single-layer PCB. In this paper, bare high-density double-layer PCB inspection based on ECT technique is studied. Defect points occurred on both top and scanning only over the top layer identifies bottom layers.