Kim Hyung-Jun, Nam Song-Min
Department of Electronic Materials Engineering, Kwangwoon University, 447-1 Wolgye-dong, Nowon-gu, Seoul 139-701, South Korea.
Nanoscale Res Lett. 2012 Jan 27;7(1):92. doi: 10.1186/1556-276X-7-92.
Low temperature fabrication of Al2O3-polyimide composite substrates was carried out by an aerosol deposition process using a mixture of Al2O3 and polyimide starting powders. The microstructures and dielectric properties of the composite thick films in relation to their Al2O3 contents were characterized by X-ray diffraction analysis. As a result, the crystallite size of α-Al2O3 calculated from Scherrer's formula was increased from 26 to 52 nm as the polyimide ratio in the starting powders increased from 4 to 12 vol.% due to the crushing of the Al2O3 powder being reduced by the shock-absorbing effect of the polyimide powder. The Al2O3-polyimide composite thick films showed a high loss tangent with a large frequency dependence when a mixed powder of 12 vol.% polyimide was used due to the nonuniform microstructure with a rough surface. The Al2O3-polyimide composite thick films showed uniform composite structures with a low loss tangent of less than 0.01 at 1 MHz and a high Al2O3 content of more than 75 vol.% when a mixed powder of 8 vol.% polyimide was used. Moreover, the Al2O3-polyimide composite thick films had extremely high Al2O3 contents of 95 vol.% and showed a dense microstructure close to that of the Al2O3 thick films when a mixed powder of 4 vol.% polyimide was used.
采用气溶胶沉积工艺，使用氧化铝和聚酰亚胺起始粉末的混合物进行了低温制备Al2O3-聚酰亚胺复合基板的实验。通过X射线衍射分析对复合厚膜的微观结构和介电性能与其Al2O3含量的关系进行了表征。结果表明，由于聚酰亚胺粉末的减震作用减少了Al2O3粉末的破碎，根据谢乐公式计算，随着起始粉末中聚酰亚胺比例从4 vol.%增加到12 vol.%，α-Al2O3的微晶尺寸从26 nm增加到52 nm。当使用12 vol.%聚酰亚胺的混合粉末时，由于表面粗糙的微观结构不均匀，Al2O3-聚酰亚胺复合厚膜表现出高损耗角正切且频率依赖性大。当使用8 vol.%聚酰亚胺的混合粉末时，Al2O3-聚酰亚胺复合厚膜呈现出均匀的复合结构，在1 MHz时损耗角正切小于0.01，Al2O3含量高于75 vol.%。此外，当使用4 vol.%聚酰亚胺的混合粉末时，Al2O3-聚酰亚胺复合厚膜具有95 vol.%的极高Al2O3含量，并且呈现出接近Al2O3厚膜的致密微观结构。
