【作者】 冒小峰；

【导师】 张军营；

【作者基本信息】 北京化工大学 ， 材料学， 2009， 硕士

【摘要】 伴随着电子集成电路的运用和微型化,使得电子器件的热量趋于集中,难以散发,给电子器件的使用安全和使用寿命带来了很多的负面影响。而导热材料的使用往往使这些困扰人们的问题迎刃而解。导热材料尤其是导热灌封料的应用不仅可以有效的使电子器件产生的热量及时散发,保证器件的使用安全,还可以有效的起到防尘、防振的效果,大大延长器件的使用寿命。本文研究了各种导热绝缘粉体对导热胶的各种应用性能的影响。研制了有机硅橡胶为基体材料的导热绝缘复合材料。然后参照Agari Y的导热模型建立了新的适用于高填充的导热模型,并给出了合理的解释。采用导热率高的导热陶瓷材料可以明显有效提高聚合物的材料的导热性能。用氧化铝粉体对有机硅橡胶进行填充改性时,随着氧化铝粉体填充量的提高,复合材料的导热率逐渐提高。复合材料的导热率不仅与氧化铝粉体的填充量有关,而且与氧化铝填充粉体的粒径有关。当氧化铝粉体的粒径分布在5-6微米之间时,复合材料的导热率随着粉体粒径的增大而提高。当氧化铝粉体的粒径只有150纳米时,复合材料的导热率伴随着填充量的提高而显著提高,当填充量相同时,复合材料的导热率要高于大粒径粉体的填充效果。本文采用导热仪测试导热填料改性有机硅橡胶得到的复合材料的导热率,发现用陶瓷导热粉体对聚合物改性使导热率与粉体的体积含量几乎呈线性关系,但是,当粉体含量超过40%,复合材料的导热率有激增的趋势。采用旋转粘度计对陶瓷粉体填充聚合物基体材料得到的基胶进行粘度测试。通过测试我们发现:(1)伴随着粉体体积含量的提高,基胶的粘度逐渐提高,粉体体积含量超过一定值时,基胶的粘度会出现一个突变点,在此点之后基胶的粘度随粉体含量变化明显。(2)当粉体含量相同时,基胶的粘度随着粉体粒径的降低而提高。采用电镜分析,观察了粉体在基体材料中的分布状态。发现粉体在基体材料中分布较为均匀,团聚现象较少。通过电镜分析明显可以看出粒径大小对粉体在基体材料分数状态的影响,从而给出了导热性能差异的合理解释。更多还原

【Abstract】 Electronic products have been applied widely with the development and application of integrated circuits. Electronic products has been an indispensable part of modern human civilization. And accompanied by the use of integrated circuits and miniaturization technologies, the distribute of thermal is becoming more and more difficult. It has brought a lot of negative impact on safety performance and life of electric products. Thermal conductive material often used as the solution to this problem. The products not onlyhave higher thermal conductivity, but also have longer life used with thermal conductive materials, especially the thermal conductive encapsulants. The thermal conductive encapsulants not only work as the thermal conductive materials, but also work as Anti-Vibration and dustproof material. In this paper, the effect of thermal conductive and insulation on application properties of composite was studied. The silicone rubber matirx thermal conductive composite was developed. And the reasonable explanation had been given for some thermal conductive phenomena based on Agari Y thermal model.The thermal conductivity of the composite could be improved significantly by filling with high conductive ceramic filler. The thermal conductivity increased gradually filled with the loading of alumina powder. The thermal conductive properties not only dominated by the volume content offiller, but also by the size and the morphology. When the size of alumina powder between 5 and 40μm in diameter, the thermal conductivity of composite increased slowly filled with the increasing load of the powder. The size of the filler is larger, the thermal conductivity of the composite is higher. Compared with the composite filled with large size alumina powder, the thermal conductivity of composite filled with alumina powder in 150nm increasd significantly with the increase of the load of filler and have higher conductivity than that of larger filler in the same volume fraction.In this paper, the thermal conductivity of composite was valuated by thermal Conductivity Measurement Instruments. The results showed that the relationship of thermal conductivity of composite and the content of filler can be described as a linear realationship. And thermal conductivity of silicone rubber composite increase rapidly above the point where powder accounts for 40% in volume.Rotary viscometer was employed to measure the viscosity of the mixture of silicone ruuber and powder before curing. The results showed that the viscosity of the mixture increase gradually with the loading of pwder. And the viscosoty increases rapidly above some the point where powder accounts for special value in volume.Electron microscope was taken to observe the distribution of powders. The results showed that the powder distributed in silicone rubber as a homogeneous dispersion system with little agglomeration. The effect of size on distribution of filler can be measured obviously on the picture taken by electron microscope. And reasonable explanation had been given.更多还原