Surface modification of ABS with Cr⁶⁺ free etching process in the electroless plating

ABS resin is widely used after the plating process. The traditional ABS resin surface etching process uses a chromic acid system, which is a great threat to environmental protection. This paper examines a new environment-friendly measure in the etching system, which is composed of HNO3, H2SO4, and NiSO4. With this system, the solution will be etching at 60 °C for 20 minutes on an ABS resin surface and causing the surface roughness of the ABS resin to become larger, and an increase of hydrophilicity. It is observed that the root mean square (RMS) of the surface roughness of the ABS resin increased from 3.21 nm to 27.5 nm after etching, and the surface contact angle of ABS resin decreased from 88.04° to 65.29°. After the etching process, the surface of ABS can be electroless plated successfully and the bonding force of coating and resin can reach 2.09 MPa. The FT-IR spectra and XPS analyses showed that hydroxyl and nitro groups on the ABS surface are as a result of etching treatment, which improves the bonding strength between ABS substrate and electroless copper plating. This new etching system can be a substitute for the traditional chromic acid system in the industry, which will greatly reduce the pollution caused by the traditional process.