Polyimide/Carbon Nanotubes Composite Films: A Potential for FPCB

Polyimide/carbon nanotube (CNT) composite films for potential use in more efficient flexible copper clad laminated (FCCL) films for flexible printed circuit boards (FPCB) were prepared by mixing a polyisoimide (PII) solution and a CNT suspension in NMP followed by casting, evaporation, and thermal imidization. The CNTs were modified by a nitric acid treatment in order to improve the thermal and electrical properties as well as to provide good dispersion of the CNTs in a polymer matrix. The formation of functional groups on the modified CNT was confirmed by Raman spectroscopy. Scanning electron microscopy revealed the modified CNTs to be well dispersed in the polyimide matrix with a uniform diameter of ca. 50A. The thermal stability and electrical properties of the films containing the CNTs were greatly improved due to the strong interfacial interaction and good dispersion between the polyimide matrix and modified CNTs. In addition, the thermal expansion coefficient of the composites films, as measured by thermo mechanical analysis, decreased with increasing CNT content, which is favorable for practical use in packaging and FPCB materials.