The Study Of Thermal Conduction Mechanism Of Polymer-based Composites And The Responding Factors To Influence Its High Thermal Conductive Behavior

Thermal dissipation is one of the important factorsto restrict the development of microelectronics industry development. Polymer-matrix composites of thermal conductivity of thermal interface materials(TIM) has good thermal conductivity properties and excellent flexibility. Depending on the elasticity of polymer matrix, the interface contact between the radiator and heater was effectively improved resulting in the higher heat exchange surface to realize highly heat dissipation efficiency.Silicone rubber has good flexibility, electric insulation and easy processibility, which make it more and more widely used in thermal conductivity materials. Therefore, polymer-matrix of silicone rubber draws a lot of attentions in thermal conductivity materials.In this work, we take two-component addition type liquid silicone rubber as theresin matrix. With the addition of heat-conducting spherical alumina into the matrix, the polymer-matrix thermal interface material were prepared by curing to form cross-liked thermal gaskets. We investigate the mechanism of thermal conductivity of the these thermal interface materials by steady-state heat flow method, non-steady-state heat flow method, Scanning Electron Microscope(SEM),Fourier Transform Infrared Spectroscopy(FTIR)、Thermal Gravimetric Analyzer(TGA)、X-ray Diffraction(XRD) and density scales. Furthermore, the responding factors to influence the thermal conductive behavior was carefully investigated. A novel thermal conductivity model of “through the phase” was also suggested.When single particles of spherical aluminum oxide were employed to prepared TIMs, it showed that the thermal conductivity increases with particle adding quantity of material and there exists a maximum packing density(0.6)of spherical aluminum oxide.We improved the processing technology to effective control the porosity of composites and enhance thermal performance.The porosity of the compositecould be dropped from 12% to 4% and thermal conductivity were also increased from 1.65W/(m·K)to 1.85W/(m·K).Theprinciple the accumulation of particles was also carefully investigated. It was found that the packing density ofspherical aluminum oxide particles couldbe effectively improved by different particles with different particle size. The diameter ratio(k)was an important factor to influence its thermal conductive behavior. When its value is less than 0.154, the combination of different particles was much suitable. After optimization, the maximum packing density couldreach 0.76 and thermal conductivity was3.45W/(m·K)A novel thermal conductivity model of “through the phase” was also proposed. Experimental results showed that the interface impact factor α value has no increases when the particle content was improved. As silicon carbide was used for throughout the skeleton, α value is around 0.05.