The layer thickness is the material thickness of one or more coatings on a substrate. A coating can be of organic origin – for example a lacquer layer – or of inorganic origin, for example the metal layer of an electroplating process.
Whatever the purpose of a coating – a layer thickness measurement is required for a wide variety of coatings and is used for quality control. It takes place both in the incoming goods inspection, during the manufacturing process and in the final inspection.
There are various methods of measuring the layer thickness, whereby we use the microscopic layer thickness measurement method in the cross section, which is often used as an arbitration procedure for checking and calibrating all other layer thickness measurement methods.
To prepare a cross-section, a sample is taken from the part to be examined, embedded in mounting, ground and polished. Since this destroys the part to be examined, comparable reference objects should also be available.
After the sample preparation, the thickness of the coating can be measured at a certain magnification.
The layer structure can also be measured if several layers are present, provided that these can be visually differentiated and displayed.
The measurement is independent of the composition of the layer and the base material.
In addition, it is also possible to assess the coating (defects due to inclusions, flaking, etc.).