Study of an Environmentally Friendly Surface Etching System of ABS for Improving Adhesion of Electroless Cu film

In this paper, an environmentally friendly system containing H 2 SO 4 -MnO 2 colloid was used to investigate surface etching of acrylonitrile-butadiene-styrene (ABS) resin as a replacement for the chromic acid etching solutions. The effects of the H 2 SO 4 concentrations, bath temperatures and etching times on the etching effectiveness were studied. The surface roughness and surface hydrophilicity of ABS substrates were improved greatly with the etching treatment. After the electroless plating of copper, the adhesion strength between the electroless copper and ABS substrate reached 1.19 KN m −1 , which was much higher than that required in PCB process (over 0.7 KN m −1 ). Electrical potential measurements indicated that the etching performance depended strongly on the oxidation potential of MnO 2 and the "soluble" MnO 2 concentration in the colloid. The FT-IR spectra and XPS results demonstrated that the C=C bonds of butadiene on the ABS surface were oxidized, and –COOH and –OH groups were formed on the ABS surface with the etching treatment. Meanwhile, some –C≡N groups of acrylonitrile were changed to –CONH 2 groups with etching treatment, and the –CONH 2 groups increased with the etching time. The formation of –COOH, –OH and –CONH 2 groups on the surface enhanced hydrophilicity and decreased surface contact angle, which was beneficial to improve the adhesion strength. These results suggest that the H 2 SO 4 -MnO 2 colloid is an effective and environment-friendly surface etchant for ABS surface etching.