MULTILAYER CERAMIC CAPACITOR AND METHOD FOR MANUFACTURING MULTILAYER CERAMIC CAPACITOR

• US 20180182552A1
• Filed: 12/21/2017
• Published: 06/28/2018
• Est. Priority Date: 12/22/2016
• Status: Active Grant

• Current Assignee: Murata Manufacturing Co Limited
• Original Assignee: Murata Manufacturing Co Limited
• Inventors: SAWADA, Takashi, NISHIOKA, Yoshinao, TOGO, Kenichi
• Granted Patent: US 10,734,159 B2
• Time in Patent Office: Days
• CPC Class Codes: H01G 4/008 Selection of materials
• CPC Class Codes: H01G 4/12 Ceramic dielectrics H01G4/085 takes precedence
• CPC Class Codes: H01G 4/1227 based on alkaline earth titanates
• CPC Class Codes: H01G 4/1236 based on zirconium oxides or zirconates H01G4/1263 takes precedence
• CPC Class Codes: H01G 4/232 electrically connecting two or more layers of a stacked or rolled capacitor
• CPC Class Codes: H01G 4/2325 characterised by the material of the terminals
• CPC Class Codes: H01G 4/30 Stacked capacitors H01G4/33 takes precedence

Abstract

A multilayer ceramic capacitor includes a substantially cuboid laminated body including ceramic layers and internal electrode layers laminated, and two or more exposed regions where the plurality of internal electrode layers are exposed, and external electrodes, wherein at least one of the external electrodes is an external electrode with resistance, the internal electrode layers include a first internal electrode layer and a second internal electrode layer opposed to the first internal electrode layer in the lamination direction, and the external electrode with resistance includes a thin film electrode layer in direct contact with the internal electrode layer in the exposed region, a resistive electrode layer provided on the thin film electrode layer, and an upper electrode layer provided on the resistive electrode layer, which has a lower electrical resistivity lower than the resistive electrode layer.

Claims

1. A multilayer ceramic capacitor comprising:

a substantially cuboid laminated body including a plurality of ceramic layers and a plurality of internal electrode layers that are laminated, and two or more exposed regions at which the plurality of internal electrode layers are exposed; and

external electrodes which cover the exposed regions;

wherein

at least one of the external electrodes is an external electrode with resistance;

the internal electrode layers include a first internal electrode layer and a second internal electrode layer opposed to the first internal electrode layer in the lamination direction; and

the external electrode with resistance includes;

a thin film electrode layer in direct contact with the internal electrode layer in the exposed region;

a resistive electrode layer provided on the thin film electrode layer; and

an upper electrode layer provided on the resistive electrode layer, the upper electrode layer having a lower electrical resistivity than the resistive electrode layer.

2. The multilayer ceramic capacitor according to claim 1, wherein the thin film electrode layer is disposed within a plane in which the exposed region is located at the laminated body.

3. The multilayer ceramic capacitor according to claim 1, wherein the resistive electrode layer is disposed within a plane in which the exposed region is located at the laminated body.

4. The multilayer ceramic capacitor according to claim 1, wherein

the laminated body includes a first end surface and a second end surface opposed to the first end surface, and a first side surface and a second side surface orthogonal or substantially orthogonal to the first end surface and the second end surface and opposed to each other;

the first internal electrode layer is exposed at the first end surface and the second end surface;

the second internal electrode layer is exposed at the first side surface and the second side surface; and

the external electrode covering the exposed regions at which the first internal electrode layer is exposed at the first end surface and the second end surface is the external electrode with resistance.

5. The multilayer ceramic capacitor according to claim 4, wherein the external electrode covering the exposed regions at which the second internal electrode layer is exposed at the first side surface and the second side surface is a low-resistance external electrode.

6. The multilayer ceramic capacitor according to claim 1, wherein the thin film electrode layer is a plating electrode.

7. The multilayer ceramic capacitor according to claim 1, wherein the thin film electrode layer includes at least one metal selected from the group consisting of Cu, Ni, Ag, Pd, an Ag—

Pd alloy and Au.

8. The multilayer ceramic capacitor according to claim 1, wherein the thin film electrode layer contains no glass and has a content ratio of metal per unit volume of the thin film electrode layer is about 99 vol % or higher.

9. The multilayer ceramic capacitor according to claim 1, wherein a thickness of the thin film electrode layer is about 0.5 μ

m or more and about 9 μ

m or less.

10. The multilayer ceramic capacitor according to claim 1, wherein a thickness of the thin film electrode layer is about 1 μ

m or more and about 5 μ

m or less.

11. The multilayer ceramic capacitor according to claim 1, wherein a thickness of the thin film electrode layer is about 2 μ

m or more and about 3 μ

m or less.

12. A method for manufacturing a multilayer ceramic capacitor, the method comprising:

a laminated body forming step of forming a substantially cuboid laminated body including a plurality of ceramic layers and a plurality of internal electrode layers laminated, and including two or more exposed regions where the plurality of internal electrode layers are exposed; and

a covering step of covering the exposed regions with external electrodes;

wherein

the covering step includes a first coating step of covering at least one of the exposed regions with an external electrode with resistance comprising a thin film electrode layer, a resistive electrode layer provided on the thin film electrode layer, and an upper electrode layer provided on the resistive electrode layer, the upper electrode layer being lower in electrical resistivity than the resistive electrode layer; and

in the first coating step, the thin film electrode layer is formed directly on the internal electrode layer exposed.

13. The method for manufacturing a multilayer ceramic capacitor according to claim 12, wherein the thin film electrode layer is formed by a plating method.

14. The method for manufacturing a multilayer ceramic capacitor according to claim 12, wherein

in the laminated body forming step, a first exposed region and a second exposed region opposed to the first exposed region, at which the first internal electrode layer of the internal electrode layers is exposed, and a third exposed region and a fourth exposed region opposed to the third exposed region, at which the second internal electrode layer of the internal electrodes is exposed, are formed at the surface of the laminated body;

the first coating step includes a step of forming the thin film electrode layer directly on the first internal electrode layer exposed in the first exposed region and the second exposed region; and

the covering step further includes a second coating step of forming a low-resistance external electrode directly on the second internal electrode layer exposed in the third exposed region and the fourth exposed region.

15. The method for manufacturing a multilayer ceramic capacitor according to claim 12, wherein

the first coating step includes:

a first firing step of applying a resistive electrode paste onto the thin film electrode layer, and then firing the resistive electrode paste to form the resistive electrode layer; and

a second firing step of applying an upper electrode paste onto the resistive electrode layer, and then firing the upper electrode paste to form the upper electrode layer; and

a maximum temperature in the first firing step is higher than a maximum temperature in the second firing step.

16. The method for manufacturing a multilayer ceramic capacitor according to claim 15, wherein the second coating step includes a third firing step of applying a low-resistance external electrode paste onto the second internal electrode layer exposed in the third exposed region and the fourth exposed region, and then firing the low-resistance external electrode paste.

17. The method for manufacturing a multilayer ceramic capacitor according to claim 16, wherein a maximum temperature in the third firing step is higher than a maximum temperature in the first firing step.

18. The method for manufacturing a multilayer ceramic capacitor according to claim 12, wherein the thin film electrode layer includes at least one metal selected from the group consisting of Cu, Ni, Ag, Pd, an Ag—

Pd alloy and Au.

19. The method for manufacturing a multilayer ceramic capacitor according to claim 12, wherein the thin film electrode layer contains no glass and has a content ratio of metal per unit volume of the thin film electrode layer is about 99 vol % or higher.

20. The method for manufacturing a multilayer ceramic capacitor according to claim 12, wherein a thickness of the thin film electrode layer is about 0.5 μ

m or more and about 9 μ

m or less.