Multilayer ceramic electronic device and manufacturing method of the same
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 ABO 3 , 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.
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, and has a main component that is a same as a main component of the plurality of dielectric layers,
wherein the multilayer electronic device has a substantially rectangular parallelepiped shape,
wherein each of the plurality of internal electrode layers is alternately extracted to a first end face and a second end face of the rectangular parallelepiped shape opposite to each other,
wherein the capacity section includes a first set among the plurality of internal electrode layers extracted to the first end face and a second set among the plurality of internal electrode layers extracted to the second end face, the first set and the second set facing each other,
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,
wherein the A/B ratio of the pair of cover layers is larger than the A/B ratio of the first section, and
wherein the A/B ratio of the first section is 0.98 or less.
2. The multilayer ceramic electronic device as claimed in claim 1 , wherein the A/B ratio of the first section is 0.97 or more.
3. 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.
4. 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.
5. The multilayer ceramic electronic device as claimed in claim 4 , wherein the A/B ratio of the pair of second sections is 0.95 or more.
6. 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.
7. 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.
8. 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; and
firing the multilayer structure.
9. The method as claimed in claim 8 , further comprising:
forming an internal electrode pattern on each of the second ceramic green sheets.
10. 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,
wherein the A/B ratio of the pair of cover layers is larger than the A/B ratio of the first section, and
wherein the A/B ratio of the pair of second sections is 0.96 or less.