Influence of conventional and sustainable electroless baths on autocatalytic copper deposition

This study compares the performance of commercial and eco-friendly electroless copper baths.
Formaldehyde was used as a reducer in the commercial bath, and ethylenediaminetetraacetic acid
(EDTA) as the chelating agent, and thiourea as the stabilizer, with potassium permanganate as a
brightener and sodium hydroxide to maintain pH 13.0 at 60 °C. The environmentally friendly bath
utilized potassium hydroxide to adjust the pH, polyol as the complexing agent, dimethylamine borane
(DMAB) as a reducing agent, and biodegradable methanesulfonic acid (MSA) in trace quantities. In
ideal circumstances (pH 11.0, 28 °C), benzotriazole (BTA, 1 ppm) had stabilizing effects. Atomic force
microscopy (AFM), X-ray diffraction (XRD), and scanning electron microscopy (SEM) were used to
study the coating’s shape and structure. Its electrochemical behavior was simultaneously evaluated
using Tafel polarization, electrochemical impedance spectroscopy (EIS), and cyclic voltammetry (CV).
The commercial bath produced a higher deposition rate (2.72 μm h−1) but yielded rougher surfaces
(Ra≈60 nm) with larger crystallites (25.55 nm). In contrast, the eco-friendly bath generated smoother,
finer-grained deposits (Ra≈21.62 nm; crystallite size=17.82 nm) with uniform morphology. XRD
confirmed the presence of crystalline copper in both systems. The eco-friendly bath showed excellent
corrosion resistance in electrochemical testing, with a much lower corrosion current density and a
greater charge-transfer resistance. Overall, the eco-friendly formulation delivered high-quality copper
coatings with enhanced surface properties and corrosion resistance, while minimizing environmental
impact.