Synthesis and characterization of hybrid films of polyimide and silica hollow spheres

Hybrid films were prepared with pyromellitic dianhydride (PMDA)/4,4′-oxydianiline (ODA) polyimide (PMDA-ODA PI) and amino-modified silica hollow spheres (a-SHS). Scanning electron microscopy confirmed the formation of silica hollow spheres without aggregation or deformation. Thermogravimetric analyses showed that the thermal stability of the hybrid films was superior to those of the neat PMDA-ODA PI films. The dielectric constant of the PMDA-ODA PI films was reduced from 3.33 to 2.24 for a hybrid film containing 5 wt% silica hollow spheres. On the other hand, when the content of silica hollow spheres was > 7 wt%, the dielectric constant increased due to the aggregation and collapse of silica hollow spheres. The tensile properties of the hybrid films degraded with increasing a-SHS content compared to those of the neat PMDA-ODA PI film, whereas they were still sufficient for applications as a low-k passivation coating material. [inline-graphic not available: see fulltext]