Future availability of high-temperature power inverters will advance the market share for hybrid vehicles that are highly fuel efficient and environmentally friendly. Capacitors have a significant influence on inverter lifetime, reliability, cost, and temperature of operation. Advanced power inverters require capacitors that operate under high voltage conditions at under-hood conditions and yet have minimal footprint. This need can be realized by embedding high-permittivity dielectrics within a printed wire board (PWB). The “film-on-foil” approach, where the dielectric is deposited on base-metal foil, is a promising method for embedding the capacitors within a PWB. We have deposited high-permittivity films of lead lanthanum zirconium titanate (PLZT) on nickel foils by a chemical solution deposition technique. These prefabricated film-on-foil dielectric sheets can be embedded into PWBs for inverter applications. Among the many challenges in fabricating these sheets is avoiding a reduction in capacitance density from the formation of a parasitic, low-permittivity, interfacial layer of nickel oxide during thermal processing of the PLZT. We inserted a conductive oxide buffer layer between the PLZT dielectric film and the nickel foil to hinder formation of the deleterious interfacial oxide. For PLZT films deposited on Ni foils, we measured a dielectric constant of 1300 (at 25°C) and 1800 (at 150°C), leakage current density of 6.6 × 10−9 A/cm2 (at 25°C) and 1.4 × 10−8 A/cm2 (at 150°C), and breakdown field strength >2.0 MV/cm (at 25°C). Film-on-foil dielectric films were thermally cycled (≈1000 cycles) between −50°C and +150°C with no measurable degradation in dielectric constant. Recently, we fabricated and measured a capacitance of ≈1 μF on a 12-mm-diameter film-on-foil dielectric layer. The fabrication procedures and dielectric properties of film-on-foil PLZT samples are presented in this talk.
Deep Insight into the Influences of the Intrinsic Properties of Dielectric Elastomer on the Energy-Harvesting Performance of the Dielectric Elastomer Generator
