Study Of Flexible Thermal Interface Modulation And Thermal Conductivity Based On Diamond-graphene Composite Film

With the rapid development of high-power electronic devices,our carbon-based TIMs are playing an increasingly important role in thermal management materials,and in the past,the understanding of diamond/graphene TIMs was limited to the composite of diamond and graphene particles with filler materials（e.g.,epoxy resin,polyvinyl alcohol,polydimethylsiloxane,etc.）,which led to the problems of low thermal conductivity values,poor flexibility,and poor adhesion of TIMs.In order to solve the above problems,this paper intends to investigate the vertical array diamond/graphene composite（VDG）films using literature research method and experimental method,expecting to promote the development of VDG films as a matrix for TIMs and push the development of thermal management materials to a better direction.Based on the theory that diamond and graphene have the highest thermal conductivity values in nature,the thermal conductivity of conventional and new carbon-based TIMs is analyzed in this paper.Due to many interfacial thermal resistances and phonon scattering phenomena between carbon material particles,traditional diamond and graphene TIMs cannot play the role of rapid elimination of"hot spots".Currently,the thermal conductivity value of new flexible carbon-based TIMs is maintained at about 50 W/（m·K）,which is not sufficient to solve the thermal interface heat dissipation problem of high-power electronic devices.The author used a unique one-step microwave plasma chemical vapor deposition（MPCVD）method with n-butylamine as the liquid source to prepare a novel highly thermally conductive three-dimensional VDG hybrid array film.the oriented three-dimensional thermal conduction path of VDG is regulated by the growth temperature,and the maximum longitudinal thermal conductivity values of VDG₆₀₀,VDG₇₀₀ and VDG₈₀₀ films are 57,97 and 91 W/（m·K）.In the actual TIMs performance measurements,the cooling efficiency of the system with our VDG as TIMs was higher than that of the state-of-the-art commercial TIMs.Meanwhile,we used the homogeneous gluing mechanism proposed by Qingwei Yan et al.for flexible graphene TIMs,and various attempts were made to compound the VDG films using polyvinyl alcohol solutions,including direct spin coating method,immersion method,surface modification method The results showed that the VDG films were subjected to different pre-treatment nucleation methods and template orientation methods.The results show that relying solely on the gravity of the PVA solution and changing the nucleation rate of the substrate material are not sufficient to achieve the goal of flexible stretchable VDG/organic composite,but need to create practical microporosity for VDG films to be established,and the study provides support for further development of the theory of flexible diamond/graphene TIMs.It is shown that the thermal conductivity value of the highly thermally conductive 3D VDG film is larger than that of most carbon-based materials,which is also confirmed by actual thermal simulations and finite element results.Although the goal of using it as a substrate for flexible stretchable VDG/organic composites is not achieved at present,it also shows excellent ability to solve the interfacial heat transfer problem in electronic systems,which is important for the solution and breakthrough of heat evacuation problem in high-power electronic devices.