Novel Silica Tube/Polyimide Composite Films with Variable Low Dielectric Constant

Abstract

The synthesis of silica tubes (ST) by self-assembly and preparation of the ST/PI composite films by mixing the ST and polyimides (PI) precursors in a solution of N,N-dimethylacetamide (DMAc) were discussed. The mixture was thermally imidized from 50 to 300°C to form ST/PI composite films. The dielectric constant of the composite was reduced from about 3.3 for pure PI to 2.9 for the 3 wt.- % ST/PI composite. Analysis shows that the low dielectric constant is ascribed to the effect of air stored in the silica tubes, pores and interfaces between the ST and the PI matrix in the composite.