| Epoxy resin was usually used as the packaging material for ordinary LED.With the rapid development of high power LED,epoxy cannot meet the packaging requirements of high power LED due to the high thermal resistance of epoxy(250~300 oC/W).The poor heat dissipation of the chip will increase the temperature rapidly leading to the aging of the device.Graphene is usually used to be filled into the epoxy system as a reinforced material and form the high thermal conductive composites,which are applied to the packaging of high power LED.Usually,the traditional method is simply mixing epoxy with graphene to improve the dispersion of reinforce fillers in the matrix.However,this method has come to the bottleneck due to the percolation saturation.In this study,we report a novel strategy of low cost for the rapid fabrication of graphene foams(GF)by self-assembly of graphene sheets on a 3D polymer skeleton.Then the epoxy resin was impregnated into 3DGF to obtain the epoxy composites.Based on this method,the graphene loading can be easily controlled,and the interconnected 3D network of GF in the composites results in not only highly thermal conductivity but also enhanced electrical conductivity.In this paper,by means of a variety of analysis and characterization methods,the GNPs was characterized and studied comprehensively.Then,three different methods were carried out to prepare the epoxy composites.Firstly,we utilized the Acetate filter with a unidirectional ordered structure as the template to fabricate a supported graphene structure.Based on this graphene structure,we prepared an anisotropic thermal conductive graphene/epoxy composite.Secondly,PU foam was use as template to fabricate three-dimensional graphene foam.As a result,an isotropic thermally conductive composite was successfully prepared with a great enhancement of electrical conductivity.Finally,on the basis of the previous research,we improved the efficiency of the assembly efficiency of graphene.Subsequently,we developed a rapid and low cost method to fabricate 3D graphene foam with the high frequency induction heating technique.The graphene foam/epoxy composites show an exceptionally high thermal conductivity.Furthermore,from the temperature change curve and infrared thermography obtained in the of simulation high power LED packaging test,it shows that the graphene foam/epoxy composite can effectively transfer the heat produced by LED to the air.The high thermal conductive graphene foam/epoxy composite will eventually improve the efficiency of LED and reduce the heat loss and the cost.It is potential to be applied in the packaging of microelectronic devices and 3C products. |
