Dual‐Effect Coupling for Superior Dielectric and Thermal Conductivity of Polyimide Composite Films Featuring “Crystal‐Like Phase” Structure

Abstract To match the increasing miniaturization and integration of electronic devices, higher requirements are put on the dielectric and thermal properties of the dielectrics to overcome the problems of delayed signal transmission and heat accumulation. Here, a 3D porous thermal conductivity network is successfully constructed inside the polyimide (PI) matrix by the combination of ionic liquids (IL) and calcium fluoride (CaF₂) nanofillers, motivated by the bubble‐hole forming orientation force. Benefiting from the 3D thermal network formed by IL as a porogenic template and “crystal‐like phase” structures induced by CaF₂‐ polyamide acid charge transfer, IL‐10 vol% CaF₂/PI porous film exhibits a low permittivity of 2.14 and a thermal conductivity of 7.22 W m⁻¹ K⁻¹. This design strategy breaks the bottleneck that low permittivity and high thermal conductivity in microelectronic systems are difficult to be jointly controlled, and provides a feasible solution for the development of intelligent microelectronics.