A new process for pre-treatment of electroless copper plating on the surface of mica powders with ultrasonic and nano-nickel

摘要

When performing electroless copper plating on the surface of mica powders, a new process of surface modification pretreatment by ultrasonic roughening and nano-nickel activation was examined. The surface morphology, microstructure and coating composition were characterized by scanning electron microscope (SEM), transmission electron microscopy (TEM), energy dispersive spectroscopy (EDS), the phase identification was found by X-ray diffraction (XRD) analysis, and the IR transmittance spectra of the Cu-plated mica powders were measured by FT-IR. The research shows that with ultrasonic treatment, the surface of the mica is roughened and the interlayer spacing increases result in that more nickel ions remain on the surface of the mica to become a nucleation site after reducing, and after activation, the surface of mica powders is covered with a lot of discrete nano-nickel, and the particle size is about 100 nm, forming a nucleation site. So, the copper atoms coated on the surface of the mica powders have a uniform particle size (approximately 200 nm) and high coverage. The EDS results also confirm that the main component of the coating is copper and contains a small amount of nickel. The part of ultrasonic time, pH, and surfactants were also looked into. The pH should be controlled at 12 to 13, because that the too low pH will cause the presence of cuprous oxide in the coating. The presence of PVP prevents agglomeration of copper particles and analysis by plating volume resistivity and weight gain rate shows that ultrasonic treatment for 25 min is a favored time. (C) 2019 Elsevier B.V. All rights reserved.