Study on the properties of POSS doped and modified low dielectric photosensitive PI nanocomposites

Polyimide (PI) is widely used in the fields of integrated circuits and microelectronics due to its strong structure designability and excellent dielectric properties. However, the dielectric constant and loss of traditional PI are relatively high, which cannot meet the requirements of 5G development. In this work, a fluorine-containing photosensitive PI (PSPI) with excellent solubility was prepared by a two-step method. The reactive diluents and a photoinitiator were added to prepare a PSPI resin. After UV curing, the contact angle of the PSPI film was 67.4°, and the relative dielectric constant measured at 1000 kHz was 2.51. By adding 7-phenyl-epoxy polyhedral oligomeric silsesquioxane (B-POSS) as a modifier, at a B-POSS loading of 5%, the resultant POSS/PSPI composite film achieved the maximum contact angle of 94.5°, representing a 40.2% increase compared with pure PSPI. When the B-POSS content was elevated to 7%, the composite delivered the minimum relative dielectric constant of 2.04 at 1000 kHz, which was reduced by 18.7% relative to the pristine PSPI. The addition of B-POSS improved the hydrophobicity and dielectric properties of the PSPI film. This research provides a feasible approach for obtaining low dielectric PI films with excellent comprehensive performance in the field of electronic devices.