Prototype capacitor produced by freeze tape-casting

In previous research freeze casting was used to construct ceramic-polymer composites in which the two phases are arranged in an electrically parallel configuration. By doing so, the composites exhibit dielectric constant (K) up to two orders of magnitude higher than that of composites with ceramic particles randomly dispersed in a polymer matrix. This technique has been successful with both an aqueous and camphene based ceramic slurry that is frozen uni-directionally to form a template such that ceramic aggregates are aligned in the temperature gradient direction. This technique has also been modified to process the slurry at room temperature using a tape caster. This alleviates the need for liquid nitrogen and a freeze-dryer. Transitioning the directional freezing technique to use a tape caster was successful and 20 vol.% BaTiO₃ X7R ceramic plates were produced from camphene based tapes fired at 1300°C for 2hrs. A 10 layer prototype capacitor was produced with a capacitance of 1.4 nF (K ~ 490) and low loss. This work shows that it is viable to scale the freezing technology up for future high K composite capacitor production.