Multilayer ceramic capacitor and method for manufacturing the same

Patent metadata

Field	Value
Publication number	US-12125644-B2
Application number	US-202318163211-A
Country	US
Kind code	B2
Filing date	Feb 1, 2023
Priority date	Feb 22, 2022
Publication date	Oct 22, 2024
Grant date	Oct 22, 2024

Abstract

One aspect of the present invention is a multilayer ceramic capacitor including a plurality of dielectric layers composed of a dielectric ceramic containing grains whose main component is barium titanate having a core-shell structure made up of a core part and a shell part, and grains whose main component is calcium titanate having a core-shell structure made up of a core part and a shell part; and a plurality of internal electrodes stacked alternately with each of the plurality of dielectric layers.

First claim

What is claimed:

1. A multilayer ceramic capacitor comprising:
a plurality of dielectric layers composed of a dielectric ceramic containing
grains whose main component is barium titanate and each of which has a core-shell structure constituted by a core part and a shell part, and
grains whose main component is calcium titanate and each of which has a core-shell structure constituted by a core part and a shell part; and

a plurality of internal electrodes stacked alternately with each of the plurality of dielectric layers.

2. The multilayer ceramic capacitor according to claim 1 , wherein a content percentage of Ca present in the core part is higher than a content percentage of Ca present in the shell part in the grains whose main component is the calcium titanate.

3. The multilayer ceramic capacitor according to claim 2 , wherein a content percentage of Ca present in the core part is at least four times a content percentage of Ca present in the shell part.

4. The multilayer ceramic capacitor according to claim 1 , wherein an average crystalline grain size of grains whose main component is the barium titanate is 200 nm or more and 500 nm or less.

5. The multilayer ceramic capacitor according to claim 1 , wherein an average crystalline grain size of grains whose main component is the calcium titanate is 200 nm or more and 400 nm or less.

6. The multilayer ceramic capacitor according to claim 1 , wherein a content percentage of at least a rare earth element selected from the group consisting of Ho, Dy, Y, and Yb present in the shell part of each grain whose main component is the barium titanate, and/or in the shell part of each grain whose main component is the calcium titanate, is higher than in the core part of the corresponding grain.

7. The multilayer ceramic capacitor according to claim 1 , wherein in the dielectric ceramic, a mole percentage of calcium relative to a total of barium and calcium, or (Ca/(Ba+Ca)×100), is 22 to 25 mol %.

8. The multilayer ceramic capacitor according to claim 1 , wherein a content percentage of Zr in the shell part of each grain whose main component is the barium titanate, and/or in the shell part of each grain whose main component is the calcium titanate, is higher than in the core part of the corresponding grain.

9. The multilayer ceramic capacitor according to claim 1 , wherein an amorphous phase is present in a grain boundary between at least one grain whose main component is the barium titanate and at least one grain whose main component is the calcium titanate.

10. The multilayer ceramic capacitor according to claim 1 , wherein the dielectric ceramic contains one or more elements selected from the group consisting of Mn, Mg, and Si.

11. The multilayer ceramic capacitor according to claim 1 , wherein a thickness of each of the dielectric layers is less than 0.6 μm.

12. A method for manufacturing a multilayer ceramic capacitor comprising:
a preliminary step of preparing ceramic raw material powder by blending barium titanate powder and calcium titanate powder having a larger average grain size than the barium titanate powder, and by adding a subcomponent raw material thereto;
a sheet formation step of forming ceramic green sheets by using the ceramic raw material powder obtained in the preliminary step;
a printing step of printing internal electrode patterns on the ceramic green sheets obtained in the sheet formation step;
a stacking step of forming a laminate body by stacking and pressure-bonding the ceramic green sheets after being subjected to the printing step;
a sintering step of obtaining a sintered compact by sintering the laminate body obtained in the stacking step; and
an external electrode formation step of forming an external electrode on both of one pair of opposing side surfaces of the sintered compact obtained in the sintering step.

13. The method for manufacturing a multilayer ceramic capacitor according to claim 12 , wherein an average grain size of the barium titanate powder is 20 nm or more and 150 nm or less.

14. The method for manufacturing a multilayer ceramic capacitor according to claim 13 , wherein an average grain size of the calcium titanate powder is 200 nm or more and 300 nm or less.

15. The method for manufacturing a multilayer ceramic capacitor according to claim 12 , wherein the barium titanate powder and the calcium titanate powder are blended at a ratio of 78:22 to 75:25 into the ceramic raw material powder.

16. The method for manufacturing a multilayer ceramic capacitor according to claim 12 , wherein at least one rare earth element selected from the group consisting of Ho, Dy, Y, and Yb, and at least one element selected from the group consisting of Zr, Mg, Mn, and Si are added in the form of oxide or in the form of a compound other than oxide as a subcomponent raw material.

17. The method for manufacturing a multilayer ceramic capacitor according to claim 12 , wherein a sintering additive is added to the ceramic raw material powder.

Assignees

• Taiyo Yuden Kk

Inventors

• Namiki Satoko
• Morita Koichiro
• Ryu Minoru
• Yuzakino Natsumi

Classifications

• H01G4/012

  Form of non-self-supporting electrodes · CPC title

• C04B35/64

  Burning or sintering processes (C04B33/32 takes precedence {; powder metallurgy B22F}) · CPC title

• C04B35/4682

  based on BaTiO3 perovskite phase · CPC title

• H01G4/008

  Selection of materials · CPC title

• H01G4/1227

  based on alkaline earth titanates · CPC title