Contactless measurement of conductivity of metals and semiconductors and of plating thickness of sheet conductors

Theory is developed and experimental data is presented for a noncontacting, nondestructive transient eddy current testing technique that can be used for conductivity measurements on flat surface samples over a range of at least 300<;σ<;6×10⁷ mho/m. Furthermore, this technique is shown to be useable for measurement of the thickness of plating of electrically conductive material over the range of at least 0.1 μm<;x<;50 μm. The method is based on pulse excitation of a small coil above the sample. The pulser and display unit is a commercially available time-domain reflectometer.