Study On Preparation And Properties Of Polyimide/Mesoporous Silica Composite Films

In recent years,with the rapid development of microelectronics industry and the increasing of the integration in integrated circuit.Needing to develop new high temperature resistant and low dielectric constant materials in order to solve the resistance capacitance time(RC) delay and power consumption increase caused by the decrease of feature sizes.The traditional inorganic dielectric material have not met the needs of the microelectronics industry,the advantages of organic materials gradually emerges.Especially,with the rise of the nanometer materials,organic/inorganic nanocomposites are gradually become the hotspot research.Polyimide(PI)shows excellent comprehensive performance,through putting air hole structure and high heat stability of the mesoporous silica nanoparticles into the polyimide basis to prepare polymer nanocomposite,that can obtain polyimide materials with lower dielectric constant,excellent thermal stability and mechanical properties.In this experiment,cetyl trimethyl ammonium bromide(CTAB)as template agent,ethyl orthosilicate(TEOS)as silica source,mesoporous silica nanoparticles were prepared by the sol-gel synthesis.Then used the silane coupling agent KH550 to functionalization modified the mesoporous silica in order to solve the dispersion of the mesoporous silica in polyimide matrix.Finally,PAA/mesoporous silica composite adhesive solution was prepared by in-situ polymerization,and a series of the composite film was prepared by thermal imidization.Using the transmission electron microscopy observe the morphology of the mesoporous silica,the dispersion of the mesoporous silica in the organic solution,and the size of the mesoporous.The mesoporous silica surface functional groups to be tested by Fourier transform infrared spectroscopic spectra.Using the scanning electron microscope observe surface and cross-section of the composite membrane.And test tensile strength,elongation at break,the thermal decomposition temperature,dielectric constant,dielectric loss and volume resistivity of the composite membrane.The results showed that the mesoporous silica was successfully synthesized by the sol-gel synthesis,spherical mesoporous silica with a size of about 200 nm,a pore size of about 3 nm,uniform size and regular pore channels.The surface of the mesoporous silica was successfully grafted with the amino organic chain segments after functional modification.Compared with the original mesoporous silica,the functionally modified mesoporous silica had a good dispersion effect in both organic solvent and PI basis,and the agglomeration phenomenon was remarkably improved.In terms of electrical performance,the dielectric constant of composite film was first decreased and after increased with the increase of the mesoporous silicon doping quantity.When the doping amount of the mesoporous silicon was 4wt%,the dielectric constant from the pure PI film 3.34 reduced to the minimum value 2.71.The dielectric loss of the composite film was increased,when the doping amount of mesoporous silicon was less than 3 wt%,the dielectric loss increases amplitude was smaller.The volume resistivity of the composite films was decreased with the increase of the mesoporous silica amount,and finally decreased to the magnitude of 10¹⁴?·m.The introduction of functionalized mesoporous silica enhanced the PI film but did not play the role of toughening in a certain range of doping amount.Compared with the pure PI film,the tensile strength of the composited film can reach 110.6 MPa at the doping amount of 3 wt%,but the elongation at break decreased.The introduction of functionalized mesoporous silica improved the thermal decomposition temperature of the composite films,the thermal decomposition temperature of the composite film was 598? higher than 587? of pure PI.