A Quick Determination of Metal Ion Concentration in Plating Solutions Using Low Power XRF Spectrometer

Abstract

Rapid determination of metal ion concentrations in plating solutions of eight kinds was studied with compact low-power XRF instruments equipped with a liquid flow cell. Stretched 12 micrometer polypropylene film was installed for this liquid cell. A small aliquot of the plating solution and the internal solution were weighed and put into a 5 ml plastic vial and were mixed well. The mixed solution of 2 ml in the 5 ml vial was then supplied to the liquid cell by a peristaltic pump. All XRF spectra were accumulated by real-time measurement of 30 s. The X-ray tube power was less than 2 W. The averages and differences of the metal ion concentrations of the commercial plating solutions of the eight kinds of plating solutions for nickel, copper, zinc, platinum, gold, rhodium, silver, and tin were determined respectively as 19.6＋/－0.1, 44.2＋/－0.2, 128＋/－0.1, 12.1＋/－0.2, 6.1＋/－0.04, 3.1＋/－0.02, 82.2＋/－0.4, and 16.8＋/－0.3 in g/L. The detection limits of metal ion in the five plating solutions of nickel, copper, zinc, rhodium, and silver were less than 0.3 g/L. For the platinum, the gold, and the tin plating solutions, the detection limit was obtained as 0.7－1.1 g/L by the X－ray tube background or by scattering effects. Results show that the low－power XRF spectrometer equipped with the liquid cell is a useful instrument for rapid and accurate analysis of the plating metal ion concentrations of many plating solutions.