Research On The Structure Design And Performance Of Polyimide Composite Fiber Membrane With Low Dielectric And High Thermal Conductivity

Materials with high thermal conductivity and breakdown strength have great potentials in microelectronic packaging and insulation applications.In this paper,tetrabutylammonium bromide modified graphene oxide(TGO)and KH550modified Al₂O₃ were utilized to fabricate E-TGO/PI and E-TGO/Al₂O₃/PI fiber membranes via in-situ polymerization and electrostatic spinning,which were then impregnated and subjected to thermally imidization to prepare I-TGO/PI and I-TGO/Al₂O₃/PI composite films.The structure and morphology of fillers and composites were studied,as well as the effects of fillers and impregnation on the properties of composites.The interlayer spacing of GO modified by TBAB increase obviously,and TGO can be well dispersed in PI fibers.The dielectric constant(?)and dielectric loss(tan?)of TGO/PI composites decrease first and then increase with the content of TGO,and remain at a low level(?<3.48,tan?<0.009).Compared with E-TGO/PI fiber membranes,the breakdown and mechanical properties of I-TGO/PI composite films after impregnation are significantly improved,and the breakdown strength and tensile strength are increased by more than 3 times.The heat resistance and thermal conductivity of TGO/PI composites also increase after impregnation,and both enhance with the increase of TGO content.The 5%thermal decomposition temperature(T_5%),T_g value and thermal conductivity of 1 wt%I-TGO/PI composite films are 563.18°C,331°C and 0.499 W/(m·K),respectively,which are 6.64°C,1°C and 0.068 W/(m·K)higher than that of 1 wt%E-TGO/PI,and 11.23%,3.12%and 3.4 times higher than that of pristine E-PI.Nano-Al₂O₃ modified by KH550 can significantly improve its dispersibility.With the increase of nano-Al₂O₃ content,?and tan?of TGO/Al₂O₃/PI composites increase slightly(?<3.82,tan?<0.011).Compared with E-TGO/Al₂O₃/PI,the breakdown and mechanical properties of I-TGO/Al₂O₃/PI after impregnation are significantly improved.With the increase of nano-Al₂O₃ content,the heat resistance of TGO/Al₂O₃/PI composites first increase and then decrease,while the thermal conductivity gradually increases.The T_5%and T_g values of 1 wt%E-TGO/0.75Al₂O₃/PI are 570.32°C and 340°C,respectively,which are 2.5%and 3.0%higher than those of 1 wt%E-TGO/PI.The thermal conductivity of 1 wt%I-TGO/1.00Al₂O₃/PI reach 0.594 W/(m·K),which is 0.082 W/(m·K)higher than that of 1 wt%I-TGO/1Al₂O₃/PI and 37.8%higher than that of 1 wt%E-TGO/PI.