Dielectric breakdown strength and energy storage improvement of polyimide through environmentally benign reactive ion etching plasma surface modification

Dielectric materials breakdown usually occurred from the dielectric surface, and the low breakdown strength of dielectric surface has a serious limiting effect on the energy storage performance of dielectric materials. To cope with this problem, a surface engineering strategy based on reactive ion etching (RIE) plasma modification is proposed in this paper, which significantly enhances the intrinsic dielectric strength through the synergistic effect of precise modulation of dielectric surface morphology and chemical bonding states. The RIE technique with different atmosphere conditions (Ar, O₂, CF₄) was employed to treat polyimide films at different inductively coupled plasma (ICP) powers. The experimental results show that the dielectric strength of polyimide films is effectively improved, meanwhile, high-temperature breakdown resistance of treated films are greatly enhanced. In particular, after treatment with the ICP-CF₄-300 W process, the breakdown field strength of the polyimide film reaches 355.88 MV m⁻¹ at 150 °C, showing excellent insulating properties. The energy storage density of the polyimide film was 3.24 J cm⁻³ at a field strength of 350 MV m⁻¹, and the energy storage efficiency was maintained at over 74 % under prolonged operation. Compared with the traditional surface treatment methods, the proposed RIE technology treatment scheme is compatible with the existing semiconductor production line process with lower cost and scalability. And it provides a solution with practical applications for the commercialization of high-temperature polymer film capacitors.