Improved Dielectric Constant and Breakdown Strength of Polyimide with Cyclohexane End Group via Molecular Engineering Strategy

The excellent comprehensive properties of polyimide films are very important for their applications in microelectronics and optoelectronics industries. In this paper, a new type of capped polyimide film material was prepared using tetrahydro phthalic anhydride, 4,4-Bis(3-amino phenoxy)benzophenone (BABP), and 2,3,3',4'-BiphenyLtetracarboxylic (BPDA). Cyclohexane-capping polyimide (BB-4H-PI) films were prepared by adding a small amount of tetrahydro phthalic anhydride as a capping agent which brings C=O and C=C into the molecular segment. After being capped, polyimide still retains the good chemical stability of PI. Under 1 KHz, the capped polyimide BB-4H-PI still maintains good dielectric properties with a dielectric constant of 4.0 and a dielectric loss of 0.008. The breakdown strength of capped polyimide Weibull is 263 MV/m, which is 17.5 % higher than that of uncapped polyimide films. At the same time, Cyclohexane end-capped polyimide still maintains good chemical stability, excellent thermal stability, and excellent mechanical properties. This study provides a simple and effective strategy for the design of intrinsic dielectric polymers in advanced electronic packaging and energy storage systems.