Analysis and discrimination of soldering tin samples by collinear multi-pulse laser induced breakdown spectrometry, supported by inductively coupled plasma optical emission and mass spectrometry

An assessment of the accuracy and precision of collinear multi-pulse laser induced breakdown spectrometry (MP-LIBS) analysis of soldering tin samples for their lead and tin content was performed. Quantitative results from inductively coupled plasma (ICP) atomic emission spectrometry carried out on dissolved samples were used as reference. For this latter purpose, a novel acid dissolution method was also developed that is equally suitable for leaded and lead-free solder compositions. It was found that the useful concentration range of time- and space‐integrated MP-LIBS lead and tin signals is significantly broader than for single‐pulse LIBS. Analytically useful calibration plots were obtained for up to 80 w/w% concentration for two resonance Sn lines and up to 100 w/w% concentration for three resonance Pb lines. The accuracy and precision of MP-LIBS analysis in this application was found to be 1–5%. This is sufficient for technical (semiquantitative) purposes and also provides the analytical benefits of LIBS: fast, in-situ analysis potentially also applicable to soldering joints. We also demonstrated that single-shot MP-LIBS spectra can be used for the discrimination of soldering alloys of the same nominal composition based on the trace contaminants present in the alloys. Supporting analytical information was obtained by solution sampling ICP mass spectrometry. The discrimination was tested by the use of the linear correlation, sum of squared deviation and overlapping integral functions, and it was found that the most suitable mathematic approach is the use of overlapping integrals.

► MP-LIBS analysis is possible also in the high-end concentration range.
► MP-LIBS analysis is possible even if strong resonance lines are used.
► A novel dissolution method applicable to most soldering tin samples.
► Discrimination results of soldering tin samples based on their LIBS spectra.