A porous GO/PI coating prepared via breath figure method: Low dielectric constant with improved mechanical and water resistance properties

It is important to reduce dielectric constant while maintaining or improving water resistance and mechanical properties for the practical use of porous low-dielectric materials. Herein, a composite film in which GO and fluorinated PI (FPI) contained porous structure located on the surface of flat PI film was prepared by the simple breath figure method. The incorporation of GO/surfactant can break the design contradiction between low dielectric constant and high mechanical strength for porous structure, thereby realizing the synchronous pro-motion of dielectric and mechanical properties. Moreover, the water absorption of composite film was decreased significantly due to the synergy of fluorine atoms, porous structure and GO/surfactant, guarantee its high robustness to humid stress. The dielectric, water resistance and mechanical properties of the composite film could be regulated through varying the casting humidity and GO/surfactant content. A low dielectric constant of 2.3, water absorption of 0.6 % and high tensile strength of 122 MPa, with 31.11 % and 75.88 % of decrease and 26.99 % of increase compared to flat PI film was exhibited with the GO/surfactant loading of only 0.5 wt%. The dielectric constant of composite film is still below 2.5 after moisture treatment. These excellent properties facilitate the application of GO/PI composite film in microelectronics.