Study On Heat Transfer Characteristics Of Graphite/polymer Thermal Interface Materials Based On Surface Modulation

As the problem of heat dissipation received widespread attention in the field of electronic packaging,researchers began to look for various materials with high thermal conductivity for using in different environments,of which thermal interface materials were widely studied as an indispensable part of packaging.Most of the thermal interface materials are polymer-based composites,like using aluminum powder,alumina or nano silver as a filler in thermal paste,or using other inorganic non-metallic materials such as graphite,carbon nanotubes,carbon fibers in thermal pads.The most common challenge in the preparation of composite materials is that as the amount of filler added increases,the filler reunites internally,blocking the phonon transmission path,thereby reducing the overall thermal performance and affecting the mechanical properties.Therefore,in this work,we select graphite materials with ultra-high thermal conductivity as filler and perform regulation on surface functional groups,and studies the overall effect of functional group regulation on graphite thermal interface materials and the impact of micro-contact thermal resistance between graphite and silicone.The main research contents and conclusions are as follows:(1)Graphite powder were pretreated by a strong oxidant,and then combined with wet modification,the silane coupling agents and titanate coupling agents with different chain lengths were grafted on the surface.Experiments showed that this method is simple to implement and suitable for grafting of a variety of coupling agents.(2)With a certain proportion,the modified graphite powder and graphite microplates were used to prepare polymer-based thermal interface materials.Compared the thermal and mechanical properties of the two groups of samples before and after surface modification,it is found that the regulation of the graphite surface will improve the dispersion degree of graphite in the polymer matrix,and significantly improve the overall mechanical properties,even without significant improvement of the overall thermal transport properties.(3)The effect of the self-assembled molecular layer formed by plasma-assisted modification on the contact thermal resistance between the graphite film and the silicone base is studied by non-contact photothermal technique.Compared with the original graphite film,the contact thermal resistance between the modified graphite film and the silicone is reduced by an order of magnitude,which was also confirmed by the non-equilibrium molecular dynamics study.