Multilayer ceramic capacitor and method for manufacturing same

1. A multilayer ceramic capacitor, comprising:

a layered body in which dielectric layers made of a ceramic dielectric material and internal electrode layers having a base metal as a main component thereof are layered alternately; and

an external electrode having an external electrode main body on a surface of said layered body and conductively connected to said internal electrodes drawn out to the surface of said layered body, and a plating layer on a surface of said external electrode main body,

said external electrode main body containing Cu; and

a protective layer containing Cu 2 O at a joining portion between said external electrode main body and said plating layer,

wherein, when heat is applied to said layered body after said external electrode is removed therefrom, and a quantity of hydrogen generated from said layered body is measured, a ratio of an arithmetic mean value Xa of a quantity of hydrogen generated per unit temperature in a range higher than or equal to 350° C. with respect to an arithmetic mean value Y of a quantity of hydrogen generated per unit temperature in a range higher than or equal to 230° C. and lower than or equal to 250° C. (Xa/Y) is less than or equal to 0.66.

2. The multilayer ceramic capacitor according to claim 1 , wherein said plating layer is a composite plating layer including an Ni-plating layer and an Sn-plating layer on said Ni-plating layer.

3. The multilayer ceramic capacitor according to claim 2 , wherein said protective layer further contains CuO.

4. The multilayer ceramic capacitor according to claim 1 , wherein said protective layer further contains CuO.

5. The multilayer ceramic capacitor according to claim 1 , wherein, when said heat is applied to said layered body after said external electrode is removed therefrom, and said quantity of the hydrogen generated from said layered body is measured, a ratio of an arithmetic mean value Xb of a quantity of hydrogen generated per unit temperature in a range of higher than or equal to 490° C. and lower than or equal to 510° C. with respect to Y (Xb/Y) is less than or equal to 0.66.

6. The multilayer ceramic capacitor according to claim 1 , wherein, when said heat is applied to said layered body after said external electrode is removed therefrom, and said quantity of the hydrogen generated from said layered body is measured, a ratio of an arithmetic mean value Xc of a quantity of hydrogen generated per unit temperature in a range higher than or equal to 400° C. and lower than or equal to 420° C. with respect to Y (Xc/Y) is less than or equal to 0.66.

7. A multilayer ceramic capacitor, comprising:

a layered body in which dielectric layers made of a ceramic dielectric material and internal electrode layers having a base metal as a main component thereof are layered alternately; and

an external electrode having an external electrode main body on a surface of said layered body and conductively connected to said internal electrodes drawn out to the surface of said layered body, and a plating layer on a surface of said external electrode main body,

said external electrode main body containing Cu; and

a protective layer containing Cu 2 O at a joining portion between said external electrode main body and said plating layer,

wherein, when heat is applied to said layered body after said external electrode is removed therefrom, and a quantity of hydrogen generated from said layered body is measured, a ratio of a maximum value Xp of a quantity of hydrogen generated per unit temperature in a range higher than or equal to 350° C. with respect to an arithmetic mean value Y of a quantity of hydrogen generated per unit temperature in a range higher than or equal to 230° C. and lower than or equal to 250° C. (Xp/Y) is less than or equal to 0.66.

8. The multilayer ceramic capacitor according to claim 7 , wherein said plating layer is a composite plating layer including an Ni-plating layer and an Sn-plating layer on said Ni-plating layer.

9. The multilayer ceramic capacitor according to claim 8 , wherein said protective layer further contains CuO.

10. The multilayer ceramic capacitor according to claim 7 , wherein said protective layer further contains CuO.

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

forming a layered body in which dielectric layers made of a ceramic dielectric material and internal electrode layers having a base metal as a main component are layered alternately;

forming an external electrode main body on a surface of said layered body so as to be conductively connected to said internal electrodes drawn out to the surface of said layered body;

forming a plating layer on a surface of said external electrode main body by electroplating to form a ceramic element main body; and

heat-treating the ceramic element body under a temperature condition higher than or equal to 150° C. so as to emit hydrogen taken into said ceramic element body during said electroplating to an outside of the ceramic element main body.

12. The method for manufacturing a multilayer ceramic capacitor according to claim 11 , wherein said external electrode main body contains Cu, and

the method further comprises performing an oxidation treatment to said external electrode main body containing Cu.

13. The method for manufacturing a multilayer ceramic capacitor according to claim 12 , wherein said oxidation treatment is performed under a condition in which a protective layer containing Cu 2 O or a protective layer containing Cu 2 O and CuO is formed on a surface of said external electrode main body.

14. The method for manufacturing a multilayer ceramic capacitor according to claim 11 , wherein said step of forming said plating layer includes forming an Ni-plating layer on a surface of said external electrode main body by electroplating, and

forming an Sn-plating layer on a surface of said Ni-plating layer by electroplating after said heat treatment.