A low-pollution surface modification system for improving the adhesion of polycarbonate

Abstract

In the present study, the surface adhesion capacity of polycarbonate (PC) has been improved by using a low-pollution surface modification system that includes alkaline potassium ferrate (K2FeO4). The effects of environmentally friendly swelling conditions, NaOH and K2FeO4 contents, and other modification conditions on the PC surface topography, hydrophilicity, and surface roughness were then primarily studied. The modification resulted in an improvement of the hydrophilic property of the PC surface. There was a significant reduction in the surface contact angle from 97.6° to 34.1°. A considerable increase in the PC surface’s average surface roughness (Ra) was also observed, which increased from 2 nm to 209 nm. Meanwhile, after chemical copper plating, the maximum peel strength between the PC resin and copper layer reached 1.13 kN/m. Furthermore, infrared absorption spectroscopy (FT–IR) and X–ray photoelectron spectroscopy (XPS) was used in the analyses of the surface chemical structure of the PC substrate, both prior to and after surface treatments. The results indicated that the modification of the surface led to increased hydrophilic groups on the PC surface, which was advantageous for the subsequent PC treatments (involving chemical copper plating). In short, the PC surface modification increased surface roughness and surface hydrophilicity, which improved the bonding between the chemically plated copper layer and the PC substrate.