X-ray fluorescence analysis (XRF) for non-destructive measurement of layer thicknesses and trace analysis
Examples of possible analyses:
- Composition (inter alia „lead-free„ substances) and coating thicknesses of solder contacts of electronic components
- Identification respectively determination of the elemental composition of unknown substances
- RoHS screening in view of mercury, chromium, cadmium, lead and bromine
- Non-destructive measurement of surface finishes of bare printed circuit boards
- Hotspot mapping for identification of solder joints containing lead on assembled printed circuit boards
The non-destructive measurement XRF is the most frequently used method for qualitative and quantitative determination of layer thicknesses of a sample in the nanometer and micrometer scale.
For the qualification or quality control of coatings in series production the hard gold plating on plug connectors or layer thicknesses of printed circuit board finishes for example, can be examined quickly and non-destructively. Also the identification or determination of the elemental composition of unknown substances, such as inorganic impurities on printed circuit boards, is possible by using XRF.
In many cases XRF is, due to low limits of detection, suited to perform a screening of RoHS restricted substances.
Differences between XRF and energy dispersive X-ray spectroscopy (EDX/EDS) in the scanning electron microscope (SEM)
- The XRF does not use an electron beam for excitation but an X-ray tube. This enables, in addition to signifi- cantly deeper insights into the area to be inspected, especially also the examination of moist or liquid samples since vacuum is not necessary.
- Conciderably simplified sample preparation since the sample to be analyzed does not need electrical conductivity, so that even insulators such as FR4 PCBs or ceramics can be examined without any extra effort.