Multilayer ceramic capacitor

Patent metadata

Field	Value
Publication number	US-11276527-B2
Application number	US-201916574232-A
Country	US
Kind code	B2
Filing date	Sep 18, 2019
Priority date	Sep 27, 2018
Publication date	Mar 15, 2022
Grant date	Mar 15, 2022

Abstract

A multilayer ceramic capacitor that includes a laminate having a plurality of dielectric layers and a plurality of internal electrodes that are alternately stacked, and external electrodes. Each of the dielectric layers contains first crystal grains and second crystal grains that each contain Ba, Ti, and a rare-earth element. A first mole ratio M1 of the rare-earth element to the Ti in a range from an interface to 50 nm inclusive of the first crystal grains and a second mole ratio M2 of the rare-earth element to the Ti in a range of 50 nm to 100 nm inclusive from the interface satisfy 0.95≤M1/M2≤1.05. A third mole ratio M3 of the rare-earth element to the Ti in the second crystal grains is half or less of a fourth mole ratio M4 of the rare-earth element to the Ti in the first crystal grains.

First claim

What is claimed is:

1. A multilayer ceramic capacitor comprising:
a laminate having a plurality of dielectric layers and a plurality of internal electrodes that are alternately stacked;
a first external electrode on a first surface of the laminate and electrically connected to a first set of the plurality of internal electrodes extended to the first surface of the laminate; and
a second external electrode on a second surface of the laminate and electrically connected to a second set of the plurality of internal electrodes extended to the second surface of the laminate,
each of the dielectric layers containing:
first crystal grains disposed in a plane direction perpendicular to a stacking direction of the internal electrodes and that contain a solid solution of Ba, Ti, and a first rare-earth element; and
second crystal grains disposed in the plane direction and that contain a solid solution of Ba, Ti, and a second rare-earth element,
where a first mole ratio M1 is the first rare-earth element to the Ti contained in a range of 50 nm or less from an interface of the first crystal grains and a second mole ratio M2 is the first rare-earth element to the Ti contained in a range of 50 nm to 100 nm from the interface of the first crystal grains,
M1 and M2 satisfy 0.95≤M1/M2≤1.05,
a third mole ratio M3 of the second rare-earth element to the Ti in the second crystal grains is half or less of a fourth mole ratio M4 of the first rare-earth element to the Ti in the first crystal grains, and
a first concentration of the second rare-earth element contained outside of a solid solution of the second crystal grains is lower than a second concentration of the first rare-earth element contained outside of a solid solution of the first crystal grains, and
wherein the dielectric layer includes a first grain layer containing the first crystal grains continuously disposed in the plane direction and a second grain layer containing the second crystal grains continuously disposed in the plane direction.

2. The multilayer ceramic capacitor according to claim 1 ,
further comprising a third grain layer containing the second crystal grains,
the second and the third grain layers are disposed between two adjacent internal electrodes of the plurality of internal electrodes in the stacking direction, and
the first grain layer is sandwiched between the second and the third grain layers.

3. The multilayer ceramic capacitor according to claim 1 , wherein the second mole ratio M2 is 1.7 times or more of a fifth mole ratio M5 of the second rare-earth element to the Ti contained in a range of 50 nm to 100 nm from an interface of the second crystal grains.

4. The multilayer ceramic capacitor according to claim 2 , wherein the second mole ratio M2 is 1.7 times or more of a fifth mole ratio M5 of the second rare-earth element to the Ti contained in a range of 50 nm to 100 nm from an interface of the second crystal grains.

5. The multilayer ceramic capacitor according to claim 1 , wherein each of the plurality of dielectric layers has a thickness of 0.1 μm to 6.0 μm.

6. The multilayer ceramic capacitor according to claim 1 , wherein a first average grain size of the first crystal grains is larger than a second average grain size of the second crystal grains.

7. The multilayer ceramic capacitor according to claim 6 , wherein
the first average grain size is 150 nm to 500 nm, and
the second average grain size is 100 nm to 200 nm.

8. The multilayer ceramic capacitor according to claim 2 , wherein a first average grain size of the first crystal grains is larger than a second average grain size of the second crystal grains.

9. The multilayer ceramic capacitor according to claim 8 , wherein
the first average grain size is 150 nm to 500 nm, and
the second average grain size is 100 nm to 200 nm.

10. The multilayer ceramic capacitor according to claim 1 , wherein the second crystal grains have a core-shell structure in which a sixth mole ratio M6 of the second rare-earth element to the Ti contained in a range of 50 nm or less from the interface of the second crystal grains is higher than a fifth mole ratio M5 of the second rare-earth element to the Ti contained in the range of 50 nm to 100 nm from the interface of the second crystal grains.

11. The multilayer ceramic capacitor according to claim 2 , wherein the second crystal grains have a core-shell structure in which a sixth mole ratio M6 of the second rare-earth element to the Ti contained in a range of 50 nm or less from the interface of the second crystal grains is higher than a fifth mole ratio M5 of the second rare-earth element to the Ti contained in the range of 50 nm to 100 nm from the interface of the second crystal grains.

12. The multilayer ceramic capacitor according to claim 1 , wherein a content of the first rare-earth element contained in the first crystal grains is 6 parts by mole or more relative to 100 parts by mole of Ti.

13. The multilayer ceramic capacitor according to claim 1 , wherein the plurality of internal electrodes contain dielectric grains of an identical composition system as that contained in the plurality of dielectric layers.

14. The multilayer ceramic capacitor according to claim 1 , wherein the first and second rare-earth elements are selected from Dy, La, Sm, Gd, Y, Ho, and Yb.

15. A multilayer ceramic capacitor comprising:
a laminate having a plurality of dielectric layers and a plurality of internal electrodes that are alternately stacked;
a first external electrode on a first surface of the laminate and electrically connected to a first set of the plurality of internal electrodes extended to the first surface of the laminate; and
a second external electrode on a second surface of the laminate and electrically connected to a second set of the plurality of internal electrodes extended to the second surface of the laminate,
each of the dielectric layers containing:
first crystal grains disposed in a plane direction perpendicular to a stacking direction of the internal electrodes and that contain a solid solution of Ba, Ti, and a first rare-earth element; and
second crystal grains disposed in the plane direction and that contain a solid solution of Ba, Ti, and a second rare-earth element,
where a first mole ratio M1 is the first rare-earth element to the Ti contained in a range of 50 nm or less from an interface of the first crystal grains and a second mole ratio M2 is the first rare-earth element to the Ti contained in a range of 50 nm to 100 nm from the interface of the first crystal grains,
M1 and M2 satisfy 0.95≤M1/M2≤1.05,
a third mole ratio M3 of the second rare-earth element to the Ti in the second crystal grains is half or less of a fourth mole ratio M4 of the first rare-earth element to the Ti in the first crystal grains, and
a first concentration of the second rare-earth element contained outside of a solid solution of the second crystal grains is lower than a second concentration of the first rare-earth element contained outside of a solid solution of the first crystal grains,
wherein the second mole ratio M2 is 1.7 times or more of a fifth mole ratio M5 of the second rare-earth element to the Ti contained in a range of 50 nm to 100 nm from an interface of the second crystal grains.

16. The multilayer ceramic capacitor according to claim 15 , wherein a first average grain size of the first crystal grains is larger than a second average grain size of the second crystal grains.

17. The multilayer ceramic capacitor according to claim 16 , wherein
the first average grain size is 150 nm to 500 nm, and

Assignees

• Murata Manufacturing Co

Inventors

• Araki Keisuke

Classifications

• H01G4/12

  Ceramic dielectrics {(H01G4/085 takes precedence)} · CPC title

• H01G4/1227 Primary

  based on alkaline earth titanates · CPC title

• H01G4/248

  the terminals embracing or surrounding the capacitive element, e.g. caps (H01G4/252 takes precedence) · CPC title

• H01G5/14

  due to longitudinal movement of electrodes · CPC title

• H01G4/30 Primary

  Stacked capacitors (H01G4/33 takes precedence) · CPC title