This document describes a method for nondestructive measurements of the thickness of conductive coatings on nonconductive base materials. This method is based on the principle of the sheet resistivity measurement and is applicable to any conductive coatings and layers of metal and semiconductor materials. In general, the probe has to be adjusted to the conductivity and the thickness of the respective application. However, this document focusses on metallic coatings on nonconductive base materials (e.g. Copper on plastic substrates, printed circuit boards).
NOTE 1 This method also applies to the measurement of through-hole copper thickness of printed circuit boards. However, for this application a probe geometry different from the one described in this document is necessary.
NOTE 2 This method is also applicable for thickness measurements of conductive coatings on conductive base materials, if the resistivity of the coating and the base material is different. This case is not considered in this document.