Flexible ceramic film capacitors for high-temperature power electronics

Abstract

Flexible ceramic film capacitors with high dielectric constant and high breakdown strength hold special promise for applications in power electronics. We deposited lanthanum-doped lead zirconate titanate (PLZT) films on aluminum-metallized polyimide films at room temperature by an aerosol deposition (AD) process and examined the electrical and dielectric properties of the PLZT films over a wide temperature range between −55 and 175 °C. The PLZT film capacitors fabricated by high deposition rate AD process not only satisfy X8R temperature rating but also exhibit superior volumetric and gravimetric specific capacitance. At room temperature, we measured a dielectric constant of ≈85, dielectric loss of ≈0.012, energy density of ≈13.2 J/cm3 with an applied voltage of ≈1000 V. A mean dielectric breakdown field strength (EB) of ≈1.25 MV/cm was determined by Weibull analysis for the ≈8-μm-thick PLZT film capacitors fabricated on flexible aluminum-metallized polyimide substrates. These results revealed that the PLZT-based ceramic film capacitors meet the requirements for advanced high-temperature power inverters. Our results demonstrated that AD process offers the greatest potential for producing low-cost, robust, compact and light-weight ceramic film capacitors with enhanced reliability for power inverters of electrical drive vehicles and various power electronic devices that are critical for high-efficiency energy conversion and renewable energy systems. Keywords: Ceramic coating, Aerosol deposition, Film capacitor, Energy conversion, Power electronics