Origin of ultralow permittivity in polyimide/mesoporous silicate nanohybrid films with high resistivity and high breakdown strength

Ultralow dielectric permittivity (k=2.58) nanohybrid dielectric film was obtained by dispersing 3.0 wt % mesoporous silicate (MCM-41) particles with nanosize hollow channels into polyimide (PI) polymer. The ultralow k value of the hybrid film can be mainly attributed to the low k value of MCM-41 itself and the small air gaps in the hybrid films. High volume resistivity and high breakdown strength were also observed for those films. At high concentration of MCM-41 loading (>3.0 wt %), the k values of the films increased significantly due to the contribution of strong interfacial polarization and interaction among MCM-41 particles. The ultralow k feature of the PI/MCM-41 nanohybrid films was explained well by Maxwell–Garnett and Bruggeman equations. The PI/MCM-41 nanohybrid film with good thermal stability as well as excellent dielectric properties can be considered as good candidate for advanced dielectric materials.