Novel hydrothermal processing (<100°C) of ceramic-polymer composites for integral capacitor applications

Synthesis of high K thin films via low cost low temperature process remains a major challenge in realizing integral capacitors for SOP applications. The current study explores synthesis of Barium Titanate by Hydrothermal process. BaTiO₃ films using hydrothermal synthesis at temperatures less than 100°C has been reported previously. However, these films are typically porous and hence give a very low dielectric constant and low yield. Precursor films are hence heat-treated and densified at temperatures higher than 300°C to obtain a good yield and hence a high dielectric constant which makes these processes incompatible with organic based build-up processes. Hence the process was modified to infiltrate a polymer into these porous films to improve the yield, reliability and subsequent processing of these films. BaTiO₃ films were also synthesized on Titanium foils with the goal of integrating them with the standard PWB processes. Dielectric constant of 700 and specific capacitances more than 1000 nF/cm² have been achieved by this modified hydrothermal process. The microstructure of the film and the polymer infiltration can be optimized to synthesize reliable films with high dielectric constant and low loss tangent. Hence, the film morphology and thickness are being studied to optimize the processing conditions for reliable films.