Novel copper immersion coating on magnesium alloy AZ91D in an Alkaline bath

Copper immersion coating of magnesium alloys has, to date, been conducted only in acidic baths. This article describes a novel alkaline bath for copper immersion coating on AZ91D magnesium alloy. Prior to the coating process, a chemical etching process of the magnesium substrate was optimized using orthogonal experimental methodology. The copper immersion coating was then investigated with regard to the effect of pH and fluoride content in the deposition bath. It was revealed during the coating process that an increase of pH and fluoride content led to a surface film formation on the magnesium substrate. The surface film formation occurred simultaneously with copper reduction, rendering a controlled magnesium dissolution, thereby a controlled copper deposition. With optimized conditions of chemical etching and immersion coating processes, uniform copper deposits were achieved.