以溶凝膠法製備氧化矽-聚亞醯胺複合材料

Abstract

本實驗以溶凝膠法(Sol-Gel Process)製備具有低介電係數特性的氧化矽-聚亞醯胺複合材料。紅外光譜分析(FTIR)的結果顯示，含聚醯胺酸的原料可藉適當的烘烤硬化處理形成含氧化矽微粒的聚亞醯胺複合結構;熱分析實驗則分別顯示所有合成的材料均有280□C以上的玻璃轉換溫度與600□C以上的熱分解溫度，因此氧化矽-聚亞醯胺複合材料具有優良的熱穩定性質。電性量測實驗顯示，材料的介電係數與其四乙氧基矽(TEOS)的添加量有關，對有機與無機成分之間為弱鍵結的Class I複合材料而言，當TEOS含量為35%時具有最低的介電係數特性;合成時水解催化劑的比例為2時，介電係數可低至2.24。對有機與無機成分之間為強鍵結的Class II複合材料而言，當TEOS含量為30%時具有最低的介電係數特性(3.95)，但其介電係數值皆高於Class I材料。以氟化聚亞醯胺取代試片中之有機成分或添加微量的GOTMS亦能降低介電係數。微觀結構的觀察顯示，氧化矽微粒之尺寸、形狀與分佈等因素均影響材料的電性性質;當複合材料具有形狀與分佈均勻且尺寸最小的氧化矽微粒時，其具有最佳的介電係數性質。

In this work sol-gel process was applied to prepare the low dielectric silica-polyimide hybrids and their physical properties were investigated. The FTIR analysis revealed that the hybrid precursors might transform into polyimides containing finely dispersed silica particles by an appropriate curing treatment. As indicated by thermal analysis, all the hybrid specimens exhibited excellent thermal stability that they had glass transition temperatures higher than 280□C and decomposition temperatures higher than 600□C. Electrical measurement indicated that the TEOS content affected the dielectric constant of hybrids. In Class I specimen with hydrolysis ratio = 2, the finely dispersed aerogel structure resulted a dielectric constant as low as 2.24 when TEOS = 35%. As to the Class II hybrids, the minimum dielectric constant (3.95) was observed in the specimen containing □30% TEOS. Nevertheless, dielectric constants of Class II hybrids were inferior to those of Class I hybrids since the aerogels could not effectively formed. Replacement of organic component by fluorinated polyimide or addition of a small amount of GOTMS was also beneficial to the reduction of dielectric constant of the hybrids. Microstructure characterization revealed that the size, shape and distribution silica aerogels affected the dielectric properties of hybrids. The hybrid with optimum dielectric property may be achieved when a homogeneously distributed silica aerogels with ultra fine particle size was formed.