PCB Conductor Dimension and Alignment Inspection Using ECT probe with an SV-GMR Sensor

摘要

Inspection of bare printed circuit boards (PCBs) consists of evaluating not only imperfections in the PCB conductor but also PCB conductor dimensions and alignment. An eddy-current testing (ECT) probe consisting of a spin-valve giant magneto-resistance (SV-GMR) device was used as a magnetic sensor, with a planar meander coil as an exciter, and applied to PCB conductor dimension and alignment inspection. High-frequency (18MHz) excitation was used to inspect a PCB conductor, with thickness of less than 10 mum, and a high-resolution scan pitch of 20 mum enabled the examination of high-density PCBs. The characteristics and configuration of the proposed ECT probe are presented in this paper. Inspection examples of a high-density PCB with a 100 mum PCB conductor width and gap verify that the proposed ECT probe yields accurate results.