A study of adhesive improvement of a Cr–Ni alloy layer on a polyimide surface by low pressure gas plasma modification

The influence of low pressure oxygen (O2) and argon (Ar) gas plasma modification of polyimide film on the adhesion to an alloy plating layer made from chromium (Cr) and nickel (Ni) was investigated. X-ray photoelectron spectroscopy (XPS) and atomic force microscopy (AFM) were employed, respectively, to estimate the chemical and morphological status of the modified polyimide surface. Attenuated total reflectance-Fourier transform infrared (ATR-IR) spectroscopy and scanning electron microscopy (SEM) were also employed to determine the fracture mode during an adhesion durability test. The results indicated that O2 plasma treatments generated carboxyl groups, but an excess of carboxyl groups could oxidize the Cr at the interface at elevated temperatures, which led to a loss of adhesion.