Preparation and dielectric properties of nano-TiC/polyimide composite films as embedded-capacitor application

In this paper, a series of nano-titanium carbide doped polyimide (nano-TiC/PI) composite films were successfully prepared via in situ polymerization. Before addition, the TiC nanoparticles were modified by oleic acid (OA) to improve its dispersity in PI matrix. The microstructures, mechanical properties and dielectric properties of OA-modified TiC doped PI composites were investigated and compared with that of the pure-TiC/PI composites. Scanning electron microscopy (SEM) analysis showed that the dispersity of TiC nanoparticles modified by oleic acid in composite films was better than the pure TiC nanoparticles without modified. Results from mechanical property tests, including the tensile strength and the elongation at break, indicated that the addition of TiC nanoparticles decreased the mechanical properties of PI films. Compared with the pure-TiC/PI composite films, the mechanical properties of the OA-modified TiC/PI composites got a slight improvement, which was the mechanical properties of composite films with 20 vol.%. OA-modified TiC addition increased slightly (86.3 N/mm² and 5.5% respectively), nevertheless, the pure-TiC/PI composites were just 65 N/mm² and 3% respectively. The dielectric constant of 20 vol.%. TiC nanoparticles modified by OA doped PI composite film showed an average permittivity as 83, which was about 1.5 times higher than that of pure-TiC/PI composite films (55). However, the dielectric loss only rose slightly. Results of dielectric breakdown test indicated that the average breakdown field strength was improved over 67% (57 KV/mm) than pure-TiC/PI composites with 5 vol.%. (34 KV/mm). Therefore, the development of these novel polyimide composite films with favorable dielectric properties is immeasurably potential for embedded-capacitor applications.