Study On Preparation And Thermal Conductivity Of Carbon-based Polymer Composites

With the increasing demands for integration,miniaturization and high performances of electronic devices,how to effectively solve the heat dissipation problem of high-power integrated circuits has become an important challenge.It is a critical factor in this field that solving the heat dissipation problem of polymer materials used in electronic packaging.As literatures show that 3D thermal network structures can improve the heat transfer performance of polymer-based thermal interface materials(TIMs)more effectively.In this paper,carbon-based materials,namely pine needle-derived carbon(PNDC),and carbon nanofibers(CNF))are used as fillers to construct highly oriented thermally conductive frameworks and prepare composite materials with different structures,where the thermal conductivity of composite materials were studied systemically.The main work is as follows:1.Pine needle derived carbon(PNDC)was prepared by a simple carbonization method at optimized condition 700?for 2 hrs,where it shows good thermal conductive property.The systematic structural characterization indicates that this derived carbon has well aligned,interconnected network-like,and channel-shaped microstructure which benefits the interface contact.The Ag/PNDC/epoxy composite films were fabricated by vacuum infiltration technology,and the results show a much enhanced heat transportation characteristics(0.537 W m^-1K^-1)as compared to that of pure epoxy resin(0.187 W m^-1K^-1).2.Carbon nanofibers(CNF)/silver films(CNF/Ag)and thermal conductive composites with CNF/Ag as fillers were prepared by electrospinning,electrochemical deposition and low temperature sintering.Electrospinning technology can effectively constructs nanocomposite fibers with high aspect ratio and aligned arrangement.The electrochemically deposited Ag particles are completely coated on the nanofibers by low temperature sintering.Combining the advantages of both methods mentioned above,in the study of this work,CNF/Ag was used as heat conduction skeleton to prepare fillers with low thermal resistance(ITR)and high thermal conductivity.The results show that the CNF/Ag film has an ultra-high in-plane thermal conductivity of up to 55.37 W m^-1K^-1.It can be found that when the content of the filler CNF/Ag film is7.8 wt%,the through-plane thermal conductivity of the composite material is up to 1.69W m^-1K^-1,and it can also maintain good mechanical properties.3.Carbon nanofiber/boron nitride nanotube(CNF/BNNT)-silica composite material was prepared by electrospinning method and vacuum infiltration technique,thus providing the exploration on the effect of filler structure on the thermal conductivity of the composite material.It indicates that CNF/BNNT-silica gel is more conducive for the heat transfer performance than composite materials made by pure CNF.When the CNF/BNNT content is 9.1 wt%,the through-plane thermal conductivity of the composite material is as high as 1.98 W m^-1K^-1.The above research shows that building an ordered thermally conductive filler skeleton in the polymer matrix can effectively improve the through-plane thermal conductivity of the composite material.The three composite materials use different fillers to prepare thermal conductivity through vertical ordered arrangement and high-speed electrostatic spinning the skeleton provides effective channels for phonon heat transfer,thereby improving the through-plane thermal conductivity of the composite material.The three kinds of composite materials are suitable for occasions requiring a relatively low filler content in integrated circuit heat dissipation.