Coating thickness measurement technology--eddy current method

The working principle of the eddy current method is to use a probe with a high-frequency current coil to generate a high-frequency magnetic field on the surface of the tested sample, thereby causing an eddy current inside the metal, and the magnetic field generated by the eddy current reacts on the inner coil of the probe, making its impedance change and Work. As the thickness of the covering layer on the surface of the substrate changes, the distance between the probe and the metal surface of the substrate changes, and the impedance of the probe coil also changes accordingly. According to the linear relationship of the impedance value change, the thickness of various covering layers on the substrate surface can be measured.

The commonly used instruments for eddy current thickness measurement include JWH_1, JWH_3, 7504 and other Thickness Gauges.