Exploiting the Combination of Displacement and Chemical Plating for a Tailored Electroless Deposition of Palladium Films on Copper

Abstract

Various formulations for electroless deposition, to obtain continuous nanometre-sized and micrometre-sized films of palladium on copper, were compared. We deposited ultrathin films using displacement plating formulations. We obtained continuous films with an equivalent thickness between 6 and 22 nm, measured by exploiting the K-ratio method with SEM-EDS of Pd layers. The Pd films obtained in this step of the work represent a cost-effective catalytic substrate. As a second step, we selected chemical plating as the procedure to obtain palladium films with a thickness in the micrometre range. An ammonia-based Pd chemical plating bath represent one of the most effective chemical plating formulations. To prevent copper substrates from being damaged by ammonia, displacement plating with palladium was also applied as a pre-treatment to make the use of these plating baths a viable way to obtain thicker palladium coatings. Palladium films showing good adherence, compact morphology, and a thickness over 1.5 μm were obtained, proving that the combination of two different electroless techniques was the key to develop a sustainable procedure for micrometre-sized palladium coatings, which could substitute electroplating of Pd in galvanic industry for decorative applications.

Tailoring barrier layers design for haute couture through X-ray microanalysis: Insights and guidelines

“…The SEM analyses were performed at an acceleration voltage of 5 kV and 300× magnification at the centre of the disks. To obtain the equivalent diffusion thickness of diffusing species migrated to the surface (t s ), the K-ratio method [ 25 , 26 ] was employed. It is a semiquantitative methodology based on calculated calibration curves that makes possible to measure nanometric and subnanometric thicknesses typical of diffused layers.…”

Electroless Metallization of the Elements: Survey and Progress

“…Huang and co-workers 388 sensitivities ∼10-fold greater than those obtained using commercial Pd foils. Finally, Giurlani and Innocenti and co-workers 390 have recently reported a dual galvanic and EL process for the deposition of adherent Pd films onto Cu substrates for decorative applications. The Cu substrate is first treated with acidic PdCl 2 to galvanically deposit a 6−22 nm thick Pd layer onto the Cu.…”