Preparation And Performance Of High Thermal Conductivity Elastomer Thermal Interface Composite

Thermal interface materials (TIM) play a key role in cooling electroniccomponents. In order to reduce the thermal contact resistance and improveefficiency of heat transfer, TIM is used to provide an effective heat pathbetween heat sink and electronic device. The presence of interfacial thermalbarrier resistance between filler and matrix was brought out in producing thehigh thermal conductivity elastomer TIM. In this paper, a series of SiR/h-BNcomposites were prepared. To achieve the guidance of preparing high thermalconductivity of TIM, the effect of surface modification on the filler-fillernetworks, interfacial thermal barrier resistance and thermal properties ofcomposites were studied. Main contents and conclusions are as follows:1.Hexagonal boron nitride (h-BN) fillers were first coated with liquidsilicone rubber (LSR) by solution dispersion and then treated in argon plasmafor different times. The modified h-BN fillers were characterized byhigh-resolution transmission electron microscopy, X-ray photoelectronspectroscopy, and contact angle analysis. The results revealed that a thin LSRfilm several nanometers thick was tightly coated on the surface of the h-BN filler after plasma treatment, and this thin film could not be removed by48-hSoxhlet extraction with n-hexane at120oC. The plasma treatment did notchange the structure of the h-BN fillers and reduced the surface energy of theh-BN particles. The amount of tightly coated LSR increased with the plasmatreatment time in the range of1-3hours.2.SiR/h-BN composite was prepared, the payne effect was characterizedwith RPA. It was found that modification of h-BN with LSR coating andplasma treatment can slightly weaken the strength of the filler-filler networksand lower the modulus of the SiR/h-BN composite. The composites filled withthe modified h-BN exhibit significantly higher thermal conductivity than thecomposites filled with untreated h-BN. For example, the thermal conductivityof the composite filled with the3h plasma modified h-BN was twice as highas that of the composite filled with untreated h-BN, at the same h-BN volumefraction of56%. Analyzing the experimental data with a modified Bruggemanmodel, we found that the large increase in thermal conductivity was the resultof the reduction in interfacial thermal barrier resistance by plasmamodification.3.Three kinds of surface modification method were used to change thethickness of layer that coated on filler surface. The modified alumina fillerswere characterized by HRTEM, FTIR, and TGA, The results revealed that athin amorphous film was coated on the surface of the alumina filler afterirradiation vulcanization and dopamine self-polymerization. The thickness of this coating is ranged from0-1nm by using different irradiation dose and1-30nm by using different dopamine concentrations. The thicker the coatingwas, the faster the decline rate of thermal conductivity of composite.