【作者】 王剑；

【导师】 祝柏林；

【作者基本信息】 武汉科技大学 ， 材料物理与化学， 2013， 硕士

【摘要】 微电子的高集成化与高速化需要新一代的封装与基板材料同时具有高的热导率及低的介电常数与介电损耗，以保证电路的散热与信号的传输。本文以中空玻璃微球(S60HS、S38HS、K20)与陶瓷颗粒(氮化铝、氮化硼)为填料，分别以低密度聚乙烯、低密度聚乙烯与环氧树脂的共混聚合物为基体，通过热压及浇铸的方法制备复合材料。采用稳态导热系数测试仪、阻抗测试仪、傅里叶红外光谱及扫描电镜等手段表征了材料的导热、介电性能与微观结构，进而研究了填料表面改性、种类、含量、配比、粒径及基体尺寸、配比对复合材料导热性能与介电性能的影响。对于中空玻璃微球单一填充低密度聚乙烯制备的复合材料，实验结果表明：偶联剂(KH570)用量对复合材料性能有显著影响，在相同填料含量下，当KH570用量为填料质量的3%时，复合材料有最高的热导率与最低的介电常数与介电损耗。复合材料的热导率与介电常数随中空玻璃微球含量的增加而降低，介电损耗逐渐升高，S38HS填充复合材料比S60HS填充复合材料具有更低的热导率、介电常数与介电损耗。当S38HS含量为50vol%时，复合材料的介电常数仅为2.08，介电损耗为3.16×10-3。采用不同模型对复合材料的导热及介电性能进行模拟发现，Lichtenecker模型及Agari模型能较好预测复合材料的热导率，不同模型对复合材料介电常数的预测值均低于实验值。以中空玻璃微球填充低密度聚乙烯复合材料的研究为基础，采用中空玻璃微球与陶瓷颗粒混杂填充低密度聚乙烯制备复合材料，结果表明：中空玻璃微球与陶瓷颗粒的体积比为1:1时，复合材料的综合性能最优。固定填料间比例，复合材料的热导率、介电常数与介电损耗均随混杂填料含量的增加而升高，氮化硼填充体系比氮化铝填充体系具有更高的热导率、介电损耗与更低的介电常数，采用不同类型的中空玻璃微球填充复合材料的热导率相差不大，介电常数与介电损耗大小为S60HS>S38HS>Κ20。采用较小粒径的氮化铝填充复合材料的热导率与介电常数更高，而采用较小粒径的氮化硼填充复合材料的热导率与介电常数反而更低，低密度聚乙烯粒径对复合材料导热性能与介电性能影响不大。通过扫描电镜观察到材料体系内形成陶瓷颗粒包裹中空玻璃微球并相互连接构成导热网络的结构。所制备的(K20+氮化硼)/低密度聚乙烯复合材料的热导率达0.82W/(m K)，介电常数仅为2.4，介电损耗为2.65×10-3。对三相复合材料热导率的模拟发现Agari模型的预测值与实验值较吻合，而对介电常数的模拟显示不同模型预测值在低填料含量下与实验值吻合，而在高填料含量下则略高于实验值。以中空玻璃微球与陶瓷颗粒混杂填充低密度聚乙烯与环氧树脂共混聚合物基体制备复合材料，结果表明：共混基体的配比对复合材料的导热性能与介电性能有显著影响，复合材料的热导率随低密度聚乙烯占基体含量的增加先升高后降低，介电常数与介电损耗逐渐降低，当低密度聚乙烯占基体含量为30vol%时，复合材料的热导率出现最大值，这与低密度聚乙烯含量对陶瓷颗粒在环氧树脂中浓度及环氧树脂连续相的变化有关。随着混杂填料含量的增加，复合材料的热导率与介电常数逐渐升高，氮化硼填充复合材料的导热及介电性能均优于氮化铝填充的复合材料，而S60HS填充复合材料的热导率与介电常数均高于S38HS的填充体系。通过扫描电镜观察到陶瓷颗粒集中分布于环氧树脂基体内并包裹中空玻璃微球相互接触形成导热网络结构。所制备的(K20+氮化硼)/(低密度聚乙烯+环氧树脂)复合材料的热导率达0.7W/(m K)，介电常数仅为3.12，介电损耗为1.1×10-2。对复合材料热导率的模拟发现Agari模型的预测值与实验值较吻合，而对介电常数的模拟显示不同模型的预测值与预测值均存在一定差距。更多还原

【Abstract】 With the higher integration density and faster performance of the electronics, the newgeneration packaging and substrate materials with high thermal conductivity, low dielectricconstant and dielectric loss are required to guarantee the heat dissipation and singalpropagation of the integrated circuits. In this paper, the low-density polyethylene (LDPE) andthe immisible LDPE/epoxy blends reinforced with hybrid fillers containing hollow glassmicrosphere (HGM)(S60HS, S38HS, K20) and ceramic particles (aluminum nitride (AlN),boron nitride (BN)) were prepared via hot pressing and mold casting method, respectively. Thethermal and dielectric properties and microstructrue of the composites were measured byvirtue of the apparatus for measurement of the thermal conductivity, impedance analyzer,fourier transform infrared spectrometer (FT-IR) and scanning electron microscope (SEM).Moreover, the effects of surface modification, type, content, volume ratio, particle size of thefillers and volume ratio, particle size of the matrix on the thermal and dielectric properties ofthe composites were investigated.The experimental results of HGM/LDPE composites show that the thermal and dielectricproperties of the composites are influenced by the dosage of silane coupling agent (KH570),and it processes the highest thermal conductivity and lowest dielectric constant and dielectricloss when the dosage of KH570is3%of the HGM mass. The thermal conductivity anddielectric constant of the composites decrease and the dielectric loss increases with increasingthe filler content. The composite filled with S38HS processes the lowest thermal conductivity,dielectric constant and dielectric loss. The dielectric constant of2.08and the dielectric loss of3.16×10-3are obtained for50vol%S38HS filled composites. It is found that Lichteneckermodel and Agari model are adaptable for prediciting the thermal conductivity of thecomposites and the predicitive values of the dielectric constant via several typtical models arelower than the experimental data.On the basis of the study on the HGM filled LDPE composite, the results of(HGM+ceramics)/LDPE composites show that the overall performance of the compositesfilled with hybride fillers in the volume ratio of1:1is superior. The addition of hybride fillersat a certain volume ratio enhances the thermal conductivity, dielectric constant and dielectricloss of the composites, and the HGM/BN filled composites exhibit the higher thermalconductivity, dielectric loss and lower dielectric constant than that of HGM/AlN filledcomposites. The thermal conductivity of the composites filled with different HGM are almostthe same, and the dielectric constant and dielectric loss are ranked as follows: S60HS> S38HS > Κ20. The composites incorporated the smaller AlN or bigger BN particles achieve the higherthermal conductivity and dielectric constant, and the particle size of LDPE has little effects onthe properties of the composites. It is observed that the agglomerations of hybrid fillersdisperse around the LDPE matrix and the ceramic particles surround the HGM, touch eachother and form the thermal conductive networks in the composites. The high thermalconductivity of0.82W/(m K), low dielectric constant of2.4and low dielectric loss of2.65×10-3are obtained simultaneously for (K20+BN)/LDPE composites. Comparing sometypical model with experimental data of the composites, it is found that Agari model areadaptable for prediciting the thermal conductivity of the composites, and the predition of thedielectric constant shows the fitted values at low filler content and higher values at high fillercontent respectively.The experimental results of (HGM+ceramics)/(LDPE+epoxy) composites show that theblend ratio of LDPE and epoxy affects the thermal and dielectric properties of the compositesgreatly. As the volume fraction of LDPE in blended matrix increasing, the thermalconductivity of the composites firstly increases and reaches the maximum at the content of30vol%and then decreases, while the dielectric properties decrease continuously, which isattributed to the changes of ceramics concerntration in the epoxy and the continuous phase ofepoxy matrix. The composite filled with BN exhibit better performance than that of filled withAlN, and the S60HS filled composites have the higher thermal conductivity and dielectricconstant than that filled with S38HS. From SEM it is observed that ceramic particles mainlydistribute in the epoxy matrix, bypassing the HGM, and construct the thermal conductivenetworks. The high thermal conductivity of0.7W/(m K), low dielectric constant of3.12andlow dielectric loss of1.1×10-2are also obtained for (S38HS+BN)/(LDPE+epoxy) composites.It is found that values of the thermal conductivity deduced from Agari model fit well with theexperimental data and the choosed typical models are not adaptable for predict the dielectricconstant of the composites.更多还原