A new approach for determination of hexavalent chromium weight percentage in chromate conversion coatings

EU RoHS directive specified hexavalent chromium [Cr(VI)] as a hazardous substance, and the maximum allowable limit has been set to 0.1 percentage by weight (1000 ppm). RoHS-restricted Cr(VI) is still used in chemical conversion coatings (CCCs) that are used as corrosion protection layers and surface decoration layers on metal components of electronic devices. However, there is currently no standard analytical method that can be used to determine the Cr(VI) weight-weight percentage (wt%) in CCCs precisely. We have developed a new sample collecting tool that can separate only the CCCs, and adhere them to its surface. The Cr(VI) wt% was determined by measuring the sample weights and Cr(VI) weights in separated samples. From the results, we found that this newly developed tool enables to separate only the CCCs, and to determine weight percentage of Cr(VI) in the CCC films that can be performed without affecting the oxidation state of Cr.