Optimization of Pretreatment and Strike Plating Process for Direct Gold Plating on Molybdenum Substrates

The pre-treatment and gold (Au) strike plating process are optimized in this study to enhance the adhesion strength of Au plating on molybdenum (Mo) substrates. Mo demonstrates exceptional high-temperature stability and mechanical strength. It is applied to various fields including aerospace, military, and electronics, either in its uncoated form or with a plated finish. However, it is well known that plating on the Mo surface is challenging due to its reactivity and tendency to form complex oxides, which hinder adhesion. To remove the oxide layer on a Mo substrate, alkaline etching and acid activation were performed and an acidic trivalent Au strike solution was employed to optimize the Au strike process. It was confirmed that the acid activation effectively removed the oxide layer. A cyanide-based solution containing [Au(CN)4]–prevented the galvanic displacement reaction and achieved high adhesion strength between the Au strike layer and Mo substrate with a current density of 10 A/cm2. As a result, the combination of acid activation and a cyanide-based trivalent Au strike plating significantly improved the adhesion of Au deposited on a Mo substrate. This study proposes a reliable and practical methodology for optimizing of the gold strike plating process on a Mo substrate, offering meaningful insights for applications in aerospace, precision electronics, and high-temperature operating environments.