Design, Preparation And Application Of Flexible Composites With High Thermal Conductivity

With the rapid development of the electronics industry, more and more of the heatgenerated in the power element, thermal conductivity composites are increasingly highrequirements. In this paper, we study the influence of added amount of thermalconductive filler, morphology, particle size, coupling agents on the properties of thermalpads, and metal film on the thermal properties of composite materials, and prepare aflexible composite material with high thermal conductivity.The thermal conductivity of the composite material increases with increasingfiller.When the filling content is low, the filler can not form an effective thermalconductivity network chain, thermal conductivity rises slowly; while filling volumefraction reaches a certain level, the thermal conductivity increases quickly.The tensilestrength first increases and then decreases, the hardness increases.Under the premise of the same filling content, the filler morphology has animportant influence on the formation of thermal conductivity network chain. The studyshows that the flake filler can achieve higher thermal conductivity, but it can’t be filledwith a high amount.Different particle size mixed can Effectively improve the performance of thecomposite materials. The two filler The optimum particle diameter proportion of twofiller is (9~10):1, The large filler particle size should be bigger than the small9to10times. When the two filler mass ratio is6:4, the highest thermal conductivity.of thecomposite material is highest.The coupling agent can improve the compatibility of the particle and silicon gel，then improve the performance of the composites. The studies show that adding anappropriate amount of coupling agent can improve the thermal conductivity and tensilestrength of the thermal pads. The addition amount of the coupling agent depend on itselfcoated area and the specific surface area of the partcle. The hardness of the thermal padis mainly determined by the crosslink density, the influence of filler is weak.The thermal conductivity of thermal pads filled by treated spherical alumina powercan be achieved4.01W/m K, hardness is30Shore C, tensile strength is91kPa. Afterlong-term reliability test for high thermal pads, the degradation of thermal and physicalperformance is less than10%, the performance remains stable, meet the requirements of long-term use. In some cases, the thermal pads can not be replaced because of itssoftness and compression characteristics.Coupling agent complex processing and sanding the surface of the metal film canimprove the bonding strength significantly with thermal conductivity composites. Afteradded to the composite material, two reasons cause the thermal performance does notimprove, the first one is roughed surface of metal film and existing oxide layer, whichincreases interface resistance drastically.The other reason is metal film thermalconductivity in the vertical direction, so that the contribution of metal film in thermalconductivity is reduced.