Enhancement of Dimensional Stability and Optical Transparency of Colorless Organo-Soluble Polyimide by Incorporation of Silica and Cosolvent

One facile approach to synthesize colorless polyimide (PI) film with enhanced dimensional stability and optical transparency is presented. With the optimum weight ratio of cosolvent GBL/DMAc, the PI film demonstrates the highest thermal stability and optical transparency. A further improvement in dimensional stability and optical transparency is achieved by blending silica sol and coupling agent in PI solution. The PI-50wt%SiO2 film exhibits a low coefficient of thermal expansion of 26 ppm/°C, high optical transmittance at 550 nm of 90.1%, and an ultra-low yellow index less than 1.4, indicating its potential application as substrate material in advanced microelectronic applications. [Supplementary materials are available for this article. Go to the publisher's online edition of International Journal of Polymeric Materials and Polymeric Biomaterials for the SI Figures.]