Enhanced dielectric properties of flexible Cu/polymer nanocomposite films

This research studied the comprehensive dielectric properties of copper (Cu)/polyethylene terephthalate (PET) and copper/polytetrafluoroethylene (PTFE) composite films under the influence of copper nanoparticle (CuNP) sputtering time. Copper thin film was grown on flexible PET and PTFE using the ion beam sputtering technique. X-ray diffraction confirmed that CuNPs had been successfully synthesized on the polymer substrate. The electrical conductivity σ _AC of the films was measured using alternating-current conductivity impedance in the frequency range of 10²–10⁶ Hz. It increased from 1.2 × 10⁻⁶ S/cm for PET to 9.65 × 10⁻⁷ S/cm for 75 min copper/PET and from 6.38 × 10⁻⁷ S/cm for PTFE to 9.24 × 10⁻⁷ S/cm for 75 min copper/PTFE. The dielectric constant ε′ increased from 0.62 for pristine PET to 1.19 for 25 min copper/PET and from 1.88 for pristine PTFE to 2.25 for 25 min copper/PTFE at an applied frequency of 10⁵ Hz. In addition, other parameters – namely, dielectric loss ε″, dielectric modulus m and dielectric tangent constant tan δ – were investigated. The comprehensive results showed that the dielectric properties of flexible PET and PTFE polymers improved due to the deposited conductive CuNPs. Flexible copper/PET and copper/PTFE composite films are promising as dielectric substrates for modern electronic applications that can resist hard environments and have long lifetimes.