MULTILAYER CERAMIC ELECTRONIC DEVICE AND MANUFACTURING METHOD OF THE SAME

Abstract

A multilayer ceramic electronic device includes a plurality of internal electrode layers, a plurality of dielectric layers, each of which has a perovskite structure that is expressed by a general formula of ABO3, a pair of cover layers respectively provided on an upper end and a lower end in a stacking direction in a capacity section, and has a main component that is a same as a main component of the plurality of dielectric layers. The capacity section has a first section positioned in a center portion in the stacking direction and a pair of second sections outside of the first section in the stacking direction. An A/B ratio of the first section is larger than the A/B ratio of the second section. The A/B ratio of the pair of cover layers is larger than the A/B ratio of the first section.

Description

Claims

1. A multilayer ceramic electronic device comprising: a plurality of internal electrode layers that are stacked so as to face each other;a plurality of dielectric layers, each of which is provided through each of the plurality of internal electrode layers and has a perovskite structure that includes an A site element and a B site element and is expressed by a general formula of ABO3;a pair of cover layers that are respectively provided on an upper end and a lower end in a stacking direction of the plurality of internal electrode layers in a capacity section in which the plurality of internal electrode layers face each other, and has a main component that is a same as a main component of the plurality of dielectric layers,wherein the capacity section has a first section positioned in a center portion in the stacking direction and a pair of second sections outside of the first section in the stacking direction,wherein an A/B ratio of the first section is larger than the A/B ratio of the second section, andwherein the A/B ratio of the pair of cover layers is larger than the A/B ratio of the first section.

2. The multilayer ceramic electronic device as claimed in claim 1, wherein the A/B ratio of the first section is 0.98 or less.

3. The multilayer ceramic electronic device as claimed in claim 2, wherein the A/B ratio of the first section is 0.97 or more.

4. The multilayer ceramic electronic device as claimed in claim 1, wherein the A/B ratio of the pair of cover layers is 1.005 or more and 1.010 or less.

5. The multilayer ceramic electronic device as claimed in claim 1, wherein the A/B ratio of the pair of second sections is 0.96 or less.

6. The multilayer ceramic electronic device as claimed in claim 5, wherein the A/B ratio of the pair of second sections is 0.95 or more.

7. The multilayer ceramic electronic device as claimed in claim 1, wherein each thickness of the pair of second sections in a direction in which the plurality of internal electrode layers face each other is 5 µm or less.

8. The multilayer ceramic device as claimed in claim 1, wherein a main component of the plurality of dielectric layers and the pair of cover layers is barium titanate.

9. A manufacturing method of a multilayer ceramic electronic device comprising: preparing a plurality of first ceramic green sheets including ceramic having a perovskite structure that includes an A site element and a B site element and is expressed by a general formula of ABO3;preparing a plurality of second ceramic green sheets that include the ceramic and have a smaller A/B ratio than the plurality of first ceramic green sheets;preparing a pair of third ceramic green sheets that include the ceramic and have a larger A/B ratio than the plurality of first ceramic green sheets;forming an internal electrode pattern on each of the plurality of first ceramic green sheets;stacking the plurality of first ceramic green sheets on which the internal electrode layer is formed;stacking the plurality of second ceramic green sheets on an upper end and a lower end of the plurality of first ceramic green sheets that are stacked;forming a multilayer structure by respectively stacking the pair of third ceramic green sheets on an upper end and a lower end of the plurality of first ceramic green sheets and the second ceramic green sheets that are stacked; andfiring the multilayer structure.

10. The method as claimed in claim 9, further comprising: forming an internal electrode pattern on each of the second ceramic green sheets.