Designs and recent progress of intrinsic low dielectric polyimide films

The burgeoning realms of artificial intelligence, the Internet of Things and 5G communication, have engendered a consistent increase in the demand for interlayer insulation materials featuring a reduced dielectric constant, thereby enhancing the signal transmission speed as large-scale integrated circuits progressively turn towards miniaturization and high integration. Polyimide has received tremendous attention as interlayer insulating material owing to the inherent advantages including excellent thermal and chemical stability, and mechanical strength. Thus far, endeavors aimed at diminishing the dielectric constant to low (<2.5) or even ultralow (≤2.2) levels of polyimide have attracted extensive interest. Herein, starting from a brief overview of the design principles of low dielectric materials, the latest research progress in the designation of intrinsic low dielectric polyimides, including fluorinated polyimides, polyimides with rigid and bulky structures, and other intrinsic low dielectric polyimides, has been thoroughly reviewed. Furthermore, the dielectric properties, water absorption capacity, and mechanical and thermal performances of different polyimides are elucidated. Finally, the key issues and challenges faced in the advancement of intrinsic low dielectric polyimides are elaborated, and the outlooks of the design of the materials are furtherly outlined. The primary objective of this paper is to acquire comprehensive and profound insights into intrinsic low dielectric polyimides, offering solid theoretical foundations and empirical references to guide future development of next-generation polyimides endowed with exceptional dielectric properties.