Study On The Preparation And Performance Of Nano-carbon Composite Thermal Interface Material

With the miniaturization and increasing power of microelectronics, heat dissipation has become critical to the performance, reliability, and further miniaturization of microelectronics. A typical thermal solution for a microelectronic system was to utilize a thermal interface material (TIM) between the die and the heat spreader, The TIM is used to reduce the contact resistance arising from the incomplete contact between two solid surfaces.TIM effectively reduced thermal resistance because of poor contact between the interface and mismatching in thermal cycle. To reduce heat accumulation, improve thermal conduct effectiveness, insulation, vibration absorption and encapsulation.In this study, a direct current arc discharge method was used to prepare core-shell type carbon coated aluminum (Al@C) nanoparticle and carbon coated copper (Cu@C) nanaoparticle respectively first. XRD, SEM, TEM, HRTEM methods were employed to analyze the characterization of nanoparticles. It was observed apparently the core-shell structure with inner core nano metal crystallization; the outer layers are graphite-like carbon layers. It revealed a preferable coating effect and there were no visibly aggregation emerged in nanoparticles. With methyl vinyl silicone as the base rubber, filled with Al@C nanoparticles, the heat dissipation composites were prepared by using the method of mechanical blending. The SEM was employed to analysis the dispersion of Al@C nanoparticles disperse in silicone rubber which showed that the nanoparticles uniform distribution in silicone rubber. The effect of Al@C nanoparticles on thermal conductivity and coefficient of thermal expansion (CTE) of the silicone rubber were investigated and it was found that thermal conductivity of the composite increased with increasing the Al@C nanoparticles content, the thermal 'conductivity began to decrease when the Al@C volume fraction reaches 50%. The thermal conductivity was 2.633W/(m.K). The optimum filling amount of Al@C nanoparticles is 50%. The CTE decreased with the loading increasing. TGA shows that the addition of Al@C nanoparticles increases the thermal stability of the silicone rubber.AlN,Al@C,Cu@C,BN were mixed with double component silicone gel to prepared flexible thermal conductive pads with sticky surface respectively compared to the matrix。The thermal conductivity and electric volume resistivity were measured, the measurements were revealed that thermal conductivities of the pads were raised with increasing loading of fillers. The thermal conductivities were 0.842W/(m.K), 0.798W/(m.K),0.788W/(m.K),0.762W/(m.K) when 45wt% of AlN,Al@C,Cu@C,BN usage respectively. Increased 2.63,2.44,2.40,2.28 times respectively.Thermal conductivities increased slightly when temperature rose. The electric volume resistivity of Pads with Al@C,Cu@C decreased when filler usage increased. Pads with AlN and BN met insulation requirements. Silicone rubber pulps were prepared by mixed Al@C,Cu@C nanoparticles in silicone solution, dip coating were conducted when the concentration was 30wt%, volatilize solvent, used glass fiber cloth as supporting construction, a thin silicone thermal conductive pad was attained after cured and trimed.