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54 PCB007 MAGAZINE I AUGUST 2020 Article by Britta Schafsteller, Gustavo Ramos, Dirk Tews, and Dimitri Voloshyn ATOTECH DEUTSCHLAND GMBH Abstract Due to its multiple soldering and bonding capabilities, electroless nickel/electroless pal- ladium/immersion gold (ENEPIG) is a highly reliable finish with a broad application field. This article introduces a new electroless plat- ing bath to deposit pure palladium layers, which allows you to operate the process with lower palladium content and higher process robustness. The performance of the deposits is tested in various ways and compared to mar- ket proven production solutions. Introduction ENEPIG is an accepted and well-established finish for high-performance and high-reliabili- ty applications in a growing market. The nickel layer provides a reliable diffusion barrier and, at the same time, is a solderable and bondable surface finish allowing a variety of applica- tions. Yet there are some reasons slowing down the growth of the ENEPIG use in the market, in particular over the past 1.5 years. Due to the recently increasing Pd price, the process cost became of major interest, and cost reduction is one of the main targets in the ap- plication of the ENEPIG process. At the same time, the electrolytes for electroless palladium plating are well known to be sensitive to wrong handling and contaminations from outside. In this article, a new Pd plating solution will be presented that can be operated with a low Pd content while at the same time assuring high process robustness. This article focuses on the comparison of the new Pd electrolyte Pd-Core® with a conven- tional Pd plating solution. The new formulation allows a process operation with a Pd content of only 0.5 g/l, and with that, to reduce the full process costs by about 50%. At the same time, the bath can achieve a far extended bath life compared to conventional processes in the market without forming any pre- cipitation or plate-out. Plating One of the key proper- ties of the new Pd-Core® process is the low palla- dium content at which it is operated. Even though the target concentration of palladium in the solu- tion is 0.5 g/l, the bath de- Palladium Plating Increases Robustness, Lowers Cost