The aim of this study is to investigate the effect of the etching conditions on some technologically important properties of the Ni-P coating deposited by an electroless process on 3D printed PLA and PLA-flex. The influences of the temperature and the concentration of the etching sodium hydroxide solution on the deposition rate, composition, adhesion, wetting and roughness of Ni-P coatings were determined. The studies revealed that the high temperature and concentration of the etching solution did not improve the coating properties. In regard to the wetting and adhesion properties of the Ni-P coating, the best results were obtained at concentrations of the etching solution from 100 to 200 g L⁻¹ NaOH and at a temperature of 20–40°C. These conditions allow good wetting of the freshly deposited nickel. Etching plays an important role not only in improving adhesion, but also has an effect on the composition and thickness of the nickel layer.

In the metallisation of dielectrics, this process and the deposited metal layer quality is influenced by the dielectric pre-treatment, and the solution compositions for both pre-treatment and metallisation are vital for establishing the optimum operating conditions for metal layer deposition. The investigations in this study were carried out on samples of acrylonitrile–butadiene-styrene (ABS – Novodur PM/2C Type, Bayer) with a working surface of 0.1 dm². The investigated operations of the technological scheme for pre-treatment are as follows: degreasing, etching, reduction, pre-activation, activation. After passing through these operations, the ABS samples were subjected to chemical deposition of copper layers from a recently-developed solution. The copper layers were characterised by AFM, SEM, EDX, XRD and XPS analyses.

The present work presents a comprehensive and systematic study of the degreasing and etching processes which are an important part of the pre-treatment of dielectric materials. The reported investigations aim to select the appropriate operating regimes and compositions of the solutions used in these two operations. The criteria for their effectiveness are properties of subsequent nickel-phosphorus coatings deposited by chemical nickel plating process included as a finishing stage in the dielectric pretreatment. The polymer Acrylonitrile Butadiene Styrene is used as а dielectric. The changes in the roughness and surface morphology of dielectrics as a result of the degreasing and etching operations are evaluated by a profilometer-profilograph device and by scanning electron microscopy. The degreasing operation carried out in a solution of the surfactant SLS (0.3 g L⁻¹) provides more uniform etching of the surface of the dielectric. Furthermore, the addition of SLS and Pd(II) in the etching solution leads to increase in the degree of roughness of ABS compared to the samples treated in a non-additive solution, to better adhesion between the deposited metal coating and the substrate, as well as increasing of the thickness of the subsequent Ni-P coating.

Commercial electroless copper plating solution often use formaldehyde or its derivatives as reducing agent and are operated at pH values above 11. The high pH is not compatible with some dielectric or photoresist materials. In this work the non-formaldehyde electroless copper plating solution with weakly alkaline pH was developed. The influence of pH value and adding of nickel ions to the solution on deposition rate was investigated. The morphology, structure and the surface chemistry of the obtained copper layers was investigated by scanning electron microscopy (SEM), X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS).

In recent years, the specificity of the demand for selective, adaptable and inexpensive methods has always been one of the key factors in support of further research on electroless copper plating. In essence, this is a rather complex process involving several pretreatment steps. The electrolytes used are potentially unstable due to the spontaneous onset of nucleation as a result of local changes in pH or ongoing reactions between the products and the metal ions, which form insoluble salts. The aim of the present investigation has been to study the possibilities for obtaining thin copper coatings from an environmentally friendly electrolyte for electroless copper plating, which does not contain a toxic reducing agent. A comparison was made between copper layers on acrylonitrile-butadiene-styrene (ABS) polymer obtained by two different deposition techniques: the first used an environmentally friendly electrolyte for chemical copper plating without reducer, and the second – a trilonic copper electrolyte containing formaldehyde as a reducer. The following methods were used to study the morphology, structure and elemental composition of the obtained layers: scanning electron microscopy (SEM), X-ray diffraction (XRD), atomic force microscopy (AFM) and energy dispersion X-ray analysis (EDS).