Coordination of Ultralow Permittivity and Higher Thermal Conductivity of Polyimide Induced by Unique Interfacial Self‐Assembly Behavior

Upgrading the available dielectric materials is the most effective approach to solve the poor quality of signal transmission and heat buildup caused by high density integration. In this work, a design strategy for multilayer 3D porous composite networks is proposed, relying on the self‐assembly effect of “crystal‐like phase” to achieve the synergistic optimization of low permittivity and high thermal conductivity of polyimide. The obtained three‐layer porous polyimide composite film (PSLS) features an ultralow permittivity of 1.89, an in‐plane thermal conductivity as high as 13.58 W m−1 K−1, and maintains well electrical insulating property. Inspiringly, the first digital thermoacoustic generator with wide frequency response has been designed based on PSLS film. It achieves sound pressure levels up to 60.1 dB in the 20–100 kHz range and integrates the efficient sound generation of an ultrasonic generator with real‐time display. This work will provide a novel concept material for the smart electronics and electrical fields.