Multilayer ceramic capacitor

• US 6,362,947 B1
• Filed: 12/12/2000
• Issued: 03/26/2002
• Est. Priority Date: 12/24/1999
• Status: Expired due to Term

• Current Assignee: Taiyo Yuden Company Limited (Taiyo Yuden Co)
• Original Assignee: Taiyo Yuden Company Limited (Taiyo Yuden Co)
• Inventors: Chazono, Hirokazu
• Primary Examiner(s): Reichard, Dean A.
• Assistant Examiner(s): Ha, Nguyen T
• Application Number:
  US09/735,229
• Publication Number:
  US 20010006449A1
• Time in Patent Office: 469 Days
• Field of Search: 361/306.3, 361/321.2, 361/303, 361/306.1, 361/308.2, 361/310, 361/320, 361/304, 361/309, 29/254.2
• US Class Current: 361/306.3
• CPC Class Codes: H01G 4/30 Stacked capacitors H01G4/33 takes precedence
• CPC Class Codes: Y10T 29/435 Solid dielectric type

Abstract

A multilayer ceramic capacitor includes a substantially cuboid-shaped laminated body formed with alternately stacked conductive layers and ceramic dielectric layers, and a pair of external electrodes respectively disposed at opposite end portions of the laminated body. The conductive layers are corrugated, and each of the conductive layers has a nonuniform and spatially varying thickness. Thus the surface area of the conductive layers is substantially increased, which in turn results in the increment of the electrostatic capacitance of the multilayer ceramic capacitor. Further, interrupted regions having the layer thickness of zero are formed on the conductive layer and since the boundary portions are pointed toward neighboring conductive layers, a strong electric field is formed threat. Accordingly, the electrostatic capacitance becomes increased.

Claims

1. A multilayer ceramic capacitor, comprising:

a laminated body formed by alternately stacked ceramic dielectric layers and conductive layers,

wherein the ceramic dielectric layers and the conductive layers are corrugated and the conductive layers have a nonuniform thickness.

2. The multilayer ceramic capacitor of claim 1, wherein the conductive layers are provided with interrupted regions devoid of a conductive material.

3. The multilayer ceramic capacitor of claim 2, wherein boundary portions of the conductive layers, close to the interrupted regions, are curved upward or downward toward a stacking direction of the ceramic dielectric layers and the conductive layers.

4. The multilayer ceramic capacitor of claim 3, wherein a boundary portion points toward one of its neighboring conductive layers.

5. The multilayer ceramic capacitor of claim 1, wherein corrugations of the ceramic dielectric layers and the conductive layers run substantially parallel to each other.

6. The multilayer ceramic capacitor of claim 1, a conductive paste used in forming the conductive layers includes a conductive material and a ceramic material with a ratio of 100 to about 30-50 in weight.

7. The multilayer ceramic capacitor of claim 6, wherein the ceramic material is commonly used in forming the ceramic dielectric layers.

8. The multilayer ceramic capacitor of claim 1, wherein the conductive layers are formed by sintering layers of the conductive paste having a thickness of less than about 3 μ

m.

9. The multilayer ceramic capacitor of claim 8, wherein the layers of the conductive paste have a thickness of less than about 1 μ

m.

10. A method for forming the multilayer ceramic capacitor of claim 1, comprising the steps of:

stacking ceramic green sheets having a conductive paste coated thereon; and

pressing the stacked ceramic green sheets with a die having grooves on a pressing surface thereof, wherein an average depth of the grooves is between about 10 and 30% of an average thickness of a ceramic green sheet.

11. The multilayer ceramic capacitor of claim 1, wherein each conductive layer is provided with interrupted regions devoid of a conductive material, the interrupted regions being scattered in each conductive layer when viewed from the top while still preserving the continuity of each conductive layer.

12. The multilayer ceramic capacitor of claim 11, wherein boundary portions of each conductive layer, close to the interrupted regions, are curved upward or downward toward a stacking direction of the ceramic dielectric layers and the conductive layers.

13. The multilayer ceramic capacitor of claim 12, wherein a boundary portion points toward one of its neighboring conductive layers.