Investigation of useful or deleterious residual thermal stress component to the capacitance of a multilayer ceramic capacitor

The state of residual thermal stress in the active region of a multilayer ceramic capacitor (MLCC) was analysed through finite element method in order to uncover useful or deleterious stress component to the capacitance of an MLCC. A Ni-electrode layer of an as-fabricated MLCC is in tension in the in-plane direction, while a BaTiO3 layer is in compression. The change in stress state due to the external loading either in in-plane direction or in out-of-plane direction was analysed and compared with the change in the apparent capacitance in each case reported elsewhere. It was shown that the compressive in-plane stress (out-of-plane tension) component in BaTiO3 layer is beneficial to the capacitance while vice versa for in-plane tension (out-of-plane compression). The results were in accordance with the observations in single-layered ferroelectric thin film capacitors, which may be explained by the alignment of ferroelectric domains by stress field.