Corrosion inhibition of copper in ferric chloride solutions with organic inhibitors

Ferric chloride (FeCl3) has widespread use as an etchant in the PCB industry and for photochemical machining. Although the corrosion process of copper in FeCl3 is well known, the use of organic inhibitors of copper corrosion in FeCl3 solutions has not been reported. Such inhibition may allow microfabrication of special PCB designs and electrochemical sensors. Here, we investigate the inhibition of copper corrosion by FeCl3 (0.10 or 2.46 M) solutions with organic inhibitors. The most promising inhibitors are identified, investigated in 0.01 M FeCl3 solution using electrochemical techniques at different temperatures and exposure times, and the modified surfaces of copper are characterized by a variety of techniques in order to determine the inhibition mechanism. 5-methyl-1H-benzotriazole (MBTA, 65 mM) and 1H-benzotriazole (BTA, 65 mM) are found to be the most attractive inhibitors, with inhibition efficiencies between 96.5% and 99.5% at room temperature, depending on the exposure time and the measurement technique.