A Novel Analytical Method of Thallium Determination in Gold Electrodeposition

Abstract

Thallium is used in both cyanide and sulfite-based gold plating bath solutions as an additive that modulates how gold deposits on the target substrate. The level of Tl in the plating solutions has a large effect on the properties of the gold being deposited, including its microstructure and hardness. Thus, especially in commercial process applications, it is critical to be able to measure the Tl content of plating solutions accurately, quickly, and facilely in order to ensure proper quality of the products being manufactured. The cyclic voltametric behavior of Tl-containing gold plating bath solutions has been investigated, but quantification of its Tl content is unsatisfactory, either expensive and time consuming, or not accurate in complexed matrices. Here, we present a proprietary, electroanalytical method of Tl measurement that is fast and gives excellent accuracy and sensitivity, even in the presence of common bath breakdown products.