Plasma surface pretreatment to improve interfacial adhesion strengths of sputtered Cu on polyimide film

Abstract

The development of electronic communication and related fields puts forward urgent requirements for the research and development of high-frequency and high-speed flexible copper-clad laminate coating technology. However, magnetron sputtering technology faces the problem of poor adhesion between flexible metal films and polymer substrates. This study introduces reactive chemical groups on the PI surface to improve wettability and produce functional groups conducive to bonding with metals. The results showed that plasma pretreatment increases the surface roughness and increases the surface energy of PI films. Furthermore, the surface chemical structure of PI was changed. It was found that the adhesion strength of the Cu film and PI substrate was related to the formation of C-N functional groups. Results indicated that Cu films deposited on PI pretreat with Ar-N2 plasma have higher density and lower porosity. Moreover, the adhesion test revealed that the adhesion properties of Cu and PI were significantly improved by plasma pretreat.