Design and development of HMS@ZIF-8/fluorinated polybenzoxazole composite films with excellent low-k performance, mechanical properties and thermal stability

A new-type of hollow silica@ZIF-8 (HMS@ZIF-8) particle was successfully designed, fabricated and introduced into the fluorinated polybenzoxazole (6FPBO) matrix to prepare the HMS@ZIF-8/6FPBO composite film. Metal–organic frameworks (MOFs) were connected to the surface of hollow silica via covalent bonds, leading to the formation of a shell. Pre-6FPBO prepared from a precursor could be dissolved in organic solvents besides strong corrosive acids, which could protect the filler. HMS@ZIF-8/6FPBO composite films prepared through in situ polymerization and coating exhibited outstanding properties. At both high and room temperatures, the material exhibited excellent dielectric properties. The dielectric constant and dielectric loss decreased down to 2.12 and 0.04, respectively under 1 kHz with the filling of HMS@ZIF-8 particles. HMS@ZIF-8 particles as a filler, evenly dispersed in the matrix, could also improve the tensile modulus of 6FPBO. The tensile modulus of HMS@ZIF-8/6FPBO (6 wt%) increased up to 2.11 GPa, 54% higher than that of the pure 6FPBO matrix. Meanwhile, the composite films demonstrated excellent thermal stability, i.e. the 5% weight loss temperature was higher than 520 °C. This is the first report on MOFs being applied as low dielectric absorbing materials. We believe that the HMS@ZIF-8/6FPBO composite film designed and developed based on this strategy is suitable to be employed in large-scale integrated circuits owing to its excellent dielectric performance, mechanical properties and thermal stability.