Multilayer ceramic electronic device and method of production of same

Abstract

An object of the present invention is to provide a method of production of a multilayer ceramic electronic device able to prevent the multilayer ceramic electronic device from dropping in mechanical strength and causing structural defects such as cracks at a low cost even if annealing the sintered body for reoxidation, and also such a multilayer ceramic electronic device, i.e., a method of production of a multilayer ceramic electronic device including a step of stacking green sheets and internal electrode layers to obtain a green chip, a step of firing the green chip under a reducing atmosphere to obtain a sintered body, and a reoxidation step of annealing the sintered body in a predetermined annealing atmosphere gas, wherein the annealing atmosphere gas in the reoxidation step has a dew point of −50 to 0° C., and the annealing atmosphere gas in the reoxidation step has a temperature of 900 to 1100° C.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

These and other objects and features of the present invention will become clearer from the following description of the preferred embodiments given with reference to the attached drawings, wherein:

FIG. 1 is a schematic cross-sectional view of a multilayer ceramic capacitor according to an embodiment of the present invention,

FIG. 2 is a schematic view of a system (wetter) for controlling the dew point of an annealing atmosphere gas at the time of the reoxidation step of a sintered body in the method of production of a multilayer ceramic electronic device according to an embodiment of the present invention,

FIG. 3 is an enlarged view of an overlapped edge part II of internal electrodes in FIG. 1,

FIG. 4 is an electron microscope (TEM) photograph of an interface of an outer dielectric layer and an internal electrode layer positioned at the outer most layer side in the stack part and an interface of an inner dielectric layer and an internal electrode layer in the cross-section of a multilayer ceramic capacitor according to an embodiment of the present invention, and

FIG. 5 is an electron microscope (TEM) photograph of an interface of an outer dielectric layer and an internal electrode layer positioned at the outer most layer side in the stack and an interface of an inner dielectric layer and an internal electrode layer in the cross-section of a multilayer ceramic capacitor according to a comparative example of the present invention.

Claims

1. A method of production of a multilayer ceramic electronic device comprising a step of stacking green sheets and internal electrode layers to obtain a green chip,a step of firing said green chip under a reducing atmosphere to obtain a sintered body, anda reoxidation step of annealing said sintered body in a predetermined annealing atmosphere gas, whereinsaid annealing atmosphere gas in said reoxidation step has a dew point of −50 to 0° C., andsaid annealing atmosphere gas in said reoxidation step has a temperature of 900 to 1100° C.

2. The method of production of a multilayer ceramic electronic device as set forth in claim 1, wherein said internal electrode layers include a base metal.

3. The method of production of a multilayer ceramic electronic device as set forth in claim 1, wherein said annealing atmosphere gas includes N2 and H2O.

4. A multilayer ceramic electronic device obtained by the method as set forth in claim 1.

5. A multilayer ceramic electronic device comprising a stack part comprising inner dielectric layers and internal electrode layers stacked together andouter dielectric layers sandwiching the two sides of said stack part in the stacking direction, whereinthe amount of Si existing at an interface between the outer dielectric layer and the internal electrode layer positioned at the outer most side of the stack part is 0.5 to less than 2 times the amount of Si existing at an interface between the inner dielectric layer and the internal electrode layer.

6. The multilayer ceramic electronic device as set forth in claim 5, wherein said internal electrode layers include a base metal.