Preparation and Properties of Low-Dielectric Polyimide Films Containing Tert-Butyl

The design of high-performance polyimide (PI) films and understanding the relationship of the structure–dielectric property are of great significance in the field of the microelectronics industry, but are challenging. Herein, we describe the first work to construct a series of novel tert-butyl PI films (denoted as PI-1, PI-2, PI-3, and PI-4) based on a low-temperature polymerization strategy, which employed tetracarboxylic dianhydride (pyromellitic anhydride, 3,3′,4,4′-biphenyl tetracarboxylic anhydride, 4,4′-diphenyl ether dianhydride, and 3,3′,4,4′-benzophenone tetracarboxylic anhydride) and 4,4′-diamino-3,5-ditert butyl biphenyl ether as monomers. The results indicate that introducing tert-butyl branches in the main chain of PIs can enhance the free volume of the molecular chain and reduce the interaction between molecular chains of PI, resulting in a low dielectric constant. Particularly, the optimized PI-4 exhibits an excellent comprehensive performance with a high (5) wt% loss temperature (454 °C), tensile strength (117.40 MPa), and maximum hydrophobic angle (80.16°), and a low dielectric constant (2.90), which outperforms most of the results reported to date.