Electroplating is a common metal finishing or improvement process used in numerous industrial applications. The main purpose of electroplating is to provide the base material with decorative and functional properties. Certain compounds including zinc, chrome and nickel and their alloys confer both decorative and functional benefits to the substrate which meet both the manufacturer’s and end-user’s requirements.
Thickness variation is a significant challenge in the plating industry. The geometry of components ranges from simple flat surfaces to complex, uneven surfaces. Features such as recesses, cavities and holes will have a lower amount of coating deposit compared to outside corners, edges and flat areas. Although finishing specs generally state a minimum of plating thickness, over-plating would result in additional costs while under-plating results in a less ideal product. With these considerations in mind, being able to measure coating thickness quickly and accurately is important and affects product quality, and process and cost control.
X-ray fluorescence (XRF) analysis is a fast and non-destructive method for measuring coating thickness and composition of plating deposits of a broad range of materials with high accuracy. One major advantage of XRF analysis is that thickness and composition of both single and multiple coatings can be measured simultaneously. Additionally, the equipment is easy to operate and a measurement usually takes just a few seconds.
XRF is an atomic spectroscopy. X-ray fluorescence analysis has its basis in the phenomenon that, when atoms in a material sample are excited by the primary X-radiation, they generate fluorescent radiation (Fig. 2). The wavelength or energy of those fluoresced emissions is characteristic of the elemental composition of the sample material. The number of emitted photons at those specific energies represents the number of atoms (mass) of the emitting element that is present in the material. Additionally, coating thickness can be determined either by the strength of the signal from the coating materials or by the attenuation of the base’s material radiation.