Measurment of the thickness of Ni and Cu platings with the theoretical x-ray intensities

For the estimation of the thickness of electrodeposited layers on metal, the theoretical equations of fluorescent x-ray intensities, in which excitation efficiencies and mass absorption coefficients were treated as a function of wavelength, were derived by the following three methods. (1) The method using the intensities of fluorescent x-ray radiated from electrodeposited layers ... Method-1, (2) The method using the intensities of fluorescent x-ray radiated from substrate materials ... Method-2, (3) The method in which an excitation effect in the method-2 is considered. The samples prepared in this study were Ni electrodeposited on Cu substrate, Ni on Fe and Cu on Fe. The thickness of the electrodeposited layers ranged from 1 to 35 microns. The calculated values by the equations were compared with the measured fluorescent x-ray intensities and the following results were obtained. (a) Measured and calculated intensities were in good agreement when the layer was thinner than a certain value. Consequently the thickness of the electrodeposited layer can be determined in this range using the calculated x-ray intensities and the fluorescent x-ray intensities from materials much thicker than several tens micron. (b) The maximum thickness of electrodeposited Ni layer which can be measured by the method-1 was 30, 26 and 19 microns when the supplied voltages to tungsten x-ray tube were 30, 20 and 15 Kv respectively. The thickness of Ni on Cu by the method-2 was 39, 32 and 26 microns respectively. (c) When fluorescent x-ray from the electrodeposited layer caused the excitation effect to substrate materials, the effect showed a maximum at a certain thickness of the layer, 5 microns for Ni layer on Fe substrate. (author)