Control of residual stresses with post process in BaTiO3-based Ni-MLCCs

The control of residual stresses in BaTiO3-based multilayer ceramic capacitors (MLCCs), showing X7R characteristic, was performed with the post process using pressure and heat treatment. The crack length at the x plane, 35±6 μm, was dramatically reduced to 19±4 μm after the post process in the parallel direction to the electrode, showing a relatively small change from 18±3 to 14±3 μm in the perpendicular direction. The reduction of the crack length at the y and z planes was a little smaller than that at the x plane. The effect of the post process through the width direction (y direction) was superior to the length direction (x direction), especially at the x plane. The residual compressive and tensile stresses induced on the cover layer (margin regions) of MLCCs before the post process enhanced and changed to compressive stress after the post process, respectively. The maximum residual stresses of each plane after the post process were −221±54 MPa at the x plane and −328±85 MPa at the y plane in the parallel direction to the electrode and −126±56 MPa at the z plane in the perpendicular direction. There was no evidence for the tensile stress observed in MLCCs before the post process.