Reliability of Polyimide-based Thin and Flexible Capacitors with SrTiO3

The Reliability of polyimide (PI)-based flexible capacitors as discrete components was evaluated. A Pt/SrTiO3 (STO)/Pt/Ti/Mo/Ti metal-insulator-metal structure is formed on PI and covered with resin. The 300-nm-thick STO layer is sputter-deposited at 400 degrees C and the dielectric constant is approximately 140. The total thickness of the capacitor is 40 mu m. Under various stresses, such as thermal cycles, high humidity, reflow process, and bending, the capacitance change is within +/- 3% and the dielectric breakdown voltage higher than 100 V is maintained. Therefore, the PI-based STO capacitors are reliable and flexible enough for practical use on and in printed circuit boards.