Decreasing the dielectric constant and water uptake of co-polyimide films by introducing hydrophobic cross-linked networks

• DOI: 10.1016/j.eurpolymj.2018.02.024
• Publication Date: 2018-02-19T20:46:48Z
• Authors: Ningning Song; Kaixiang Shi; Huaxuan Yu; Hongyan Yao; Tengning Ma; Shiyang Zhu; Yunhe Zhang; Shaowei Guan
• Keywords: Thermal Stability

Abstract In the present study, a series of pendant-group cross-linkable co-polyimide (Co-PI) films were successfully prepared. Via thermal treatment, the cross-linkable tetrafluorostyrol pendant-groups could induce cross-linking without any chemical additives, resulting in the formation of robust cross-linked structures in the co-polyimide films. The effects of cross-linking and the amount of cross-linkable pendant-groups on the performances of co-polyimide films were studied and discussed in detail. After cross-linking, the obtained films showed the significantly lowered dielectric constants, which decreased gradually with increasing amounts of cross-linkable pendant-groups. The best dielectric properties were obtained for cross-linked Co-PI-5 film, which exhibits a dielectric constant as low as 2.48 at 1 MHz. Meanwhile, the cross-linked Co-PI-5 film demonstrated excellent moisture resistance with a water uptake of less than 0.31%. It also exhibited outstanding thermal and dimensional stability, superior chemical resistance, excellent mechanical property and surface planarity. The low dielectric constants, excellent anti-moisture performances and outstanding comprehensive properties make the cross-linked Co-PIs a good candidate for interlayer dielectrics in the near future.