Crack formation in MLCCs depending on position with and without post-heat treatment

Abstract

The crack formation behavior and mechanical properties, hardness (H), modulus (E), and fracture toughness (K (IC)), at each plane of BaTiO3 based multilayer ceramic capacitors (MLCCs) have been investigated and estimated using a nanoindentation technique, including effects of the post-heat treatment and the external electrode on the crack formation and mechanical properties. The crack length in each plane, length (x plane) and width (y plane) planes, has been measured for MLCCs with and without the post-heat treatment, as a function of the distance from the internal electrode. H and E values are 11.5-12.0 GPa and 175-190 GPa, respectively, independent of the plane and the post-heat treatment. The crack length in the x plane is smaller than that in the y plane, which is gradually increased as the indentation position is far away from the internal electrode. The external electrode affects the crack formation in regions near to the internal electrode, showing small crack length till 20 mu m from the internal electrode. K (IC) values in the x plane are larger than those in the y plane. The external electrode affects only the K (IC) values in the x plane within the error range, without effect of the post-heat treatment.