Electroless Pure Palladium Deposition On Copper As A Cu Wire Bondable Surface Finish
Authors: Mustafa Oezkoek and Arnd Kilian, Ph.D. and Hugh Roberts Company: Atotech Deutschland GmbH and Atotech USA Inc. Date Published: 10/16/2011
Abstract: The deposition of palladium on copper is not a new surface finish process. Palladium was first introduced to the market as a surface finish on copper by Atotech more than 17 years ago. At that time, it was primarily used as a surface finish for soldering. In addition, it was employed as a contact surface in applications like touch key pads. The surface finish, “Direct Electroless pure Pd on Cu finish” (pure EP finish), contains the precious metal palladium and is understandably more expensive than an organic solderability preservative (OSP) or an immersion tin surface finish. Most technical requirements in the past could be fulfilled by other surface finishes without precious metals. As such, the palladium surface finish lost the attention of the cost-driven market and was withdrawn from the market solely for commercial reasons. This paper briefly reviews the pure EP finish process and discusses issues related to production environments. Also presented are data on copper wire bonding, soldering and solder joint tests. Finally, a comparison of the ecological impact of this process to alternative processes is made.
ENEP, Direct Pd on Cu, pure EP finish, wire bonding, gold wire bonding, copper wire bonding.