Electrochemical polarisation behaviour of palladium electrolyte in a mixed system of Pd/Ni/Cu

Abstract

Abstract. The possibility of Pd-plated leadframe fabrication using maskless method was investigated. Palladium metallisation was carried out using a maskless electrochemical patterning process on a substrate of copper disc with deposited nickel pattern on its surface. An appropriate palladium electrolyte required for such system has been previously prepared. Onset potential and current densities for palladium deposition was determined. However, palladium pattern deposit could not be obtained, as the substrates were always entirely covered by palladium. This might be due to an instantaneous palladium deposition caused by displacement reaction between Pd and Cu/Ni. Therefore, a set of voltammetry experiments has been carried out to study polarisation behaviours of the mixed system Pd/Ni/Cu in a threeelectrode RDE system. These experiments were aimed to determine onset potential of palladium deposition at which displacement reaction could be avoided. However, polarisation curves especially for those of palladium and copper indicate that it was not possible to deposit palladium with no copper dissolution. At any potential where palladium deposition was possibly to occur, it was always accompanied by copper dissolution.

Electrodeposition of Pd–Ag alloy for electrical contacts

“…However, the atomic percentage of Ag in the electrodeposit was significantly higher than the plating solution regardless of the mass concentration (Table 2). The combination of Pd, AgNO 3 , and NH 4 Cl complexing agent formed a palladium complex of [Pd(NH 3 ) 4 ]Cl 2 [28] , and silver complex of [Ag (NH 3 ) 2 ]NO 3 [29]. The Pd-Ag alloy was coated using concurrent electrodeposition of Pd and Ag according to the following cathodic reactions.…”