Research on optimization of adhesion of copper film deposited on polyimide substrate by magnetron sputtering

Polyimide is a kind of high-performance polymer material, which has been widely used in many high-tech fields such as electronics, aerospace, and biomedicine due to its excellent comprehensive performance. However, in the process of preparing flexible copper clad laminate (FCCL) by magnetron sputtering, the adhesion between the copper film and the polyimide substrate is relatively low, which has become an urgent problem to be solved. In this paper, the polyimide substrate was treated by plasma etching, and a magnetron sputtering deposition equipment was used to obtain a NiCr alloy coating with a thickness of about 35 nm on the surface of polyimide. The deposition time of NiCr was selected as 15 min during the copper deposition process. The results show that the sputtering of nickel (Ni) and chromium (Cr) elements is uniform during the magnetron sputtering process, and the content ratio is approximately 4:1. The adhesion of the copper film on the polyimide surface was significantly improved to 11.38 MPa. In addition, the diffusion of metal atoms plays an important role in enhancing the adhesion of the film layer. This study selects the resistance of NiCr thin films as the research object, providing an effective technical solution to solve the problem of poor adhesion between copper films and polyimide substrates prepared by magnetron sputtering, which is of great significance.