JPH11233364A - Laminated ceramics capacitor and manufacture of the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a laminated ceramics capacitor which is superior in thermal-shock resistance and wet-load resistance by improving a dielectric layer of laminated ceramics capacitor made of internal electrode of base metal. SOLUTION: A laminated ceramics capacitor 1 provided with a plurality of dielectric ceramics layers 2a and 2b, an internal electrode 4 formed between the dielectric ceramics layers 2a and 2b, and an external electrode 5 electrically connected to the internal electrode 4. Here, the internal electrode 4 is constituted of a base metal, and a metal oxide is present so that the concentration is gradually reduced through diffusion from the interface of the internal electrode 4 and dielectric ceramics layers 2a and 2b toward inside the dielectric ceramics layers 2a and 2b.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a ceramic capacitor used for electronic equipment, and more particularly to a multilayer ceramic capacitor having an internal electrode made of a base metal and a method of manufacturing the same.

[0002]

2. Description of the Related Art When a conventional dielectric material containing barium titanate as a main component is used for a ceramic capacitor, there is a problem in that when it is fired under a neutral or reducing low oxygen partial pressure, it is reduced and becomes a semiconductor. Was. Therefore, the internal electrodes do not melt even at the temperature at which the dielectric ceramic material is sintered, and do not oxidize even when fired under a high oxygen partial pressure that does not turn the dielectric ceramic material into a semiconductor. It is necessary to use a noble metal such as Pt, which has been a major obstacle to reducing the cost of the manufactured multilayer ceramic capacitor.

Therefore, in order to solve the above-mentioned problem, it has been desired to use an inexpensive base metal such as Ni as the internal electrode. However, if such a base metal is used as an internal electrode material and is fired under conventional conditions, the electrode material is oxidized and no longer functions as an electrode. Therefore, in order to use such a base metal as an internal electrode, a ceramic material does not turn into a semiconductor even when fired in a neutral or reducing atmosphere with a low oxygen partial pressure, and a dielectric material having excellent dielectric properties is required. is necessary.

As a material satisfying this condition, for example, Japanese Patent Application Laid-Open No. Sho 62-256422 discloses BaTiO ₃ —CaZrO ₃ —
Composition of MnO-MgO system, BaTiO ₃ -MnO-MgO-rare earth oxide system of JP-A-63-103861, and BaTiO _3- (M of JP-B-61-14610)
g, Zn, Sr, Ca) O-Li 2 O-SiO 2 -MO
(MO: BaO, SrO, CaO) based composition;
No.-263708 (Ba, Ca, Sr, Mg, Ce)
(Ti, Zr) O ₃ based compositions, the Kokoku No. 5-52602 Sr (Ti, Zr) O 3 -Li 2 O-SiO 2 -MO
(MO: BaO, MgO, ZnO, SrO, CaO) based compositions have been proposed.

[0005]

However, in a multilayer ceramic capacitor having such a base metal internal electrode, when the dielectric layer is thin and a multilayer stack is formed, the difference in shrinkage between the internal electrode and the ceramic during firing is reduced. There is a problem that residual stress is generated at the interface between the internal electrode and the ceramic due to the difference in thermal expansion coefficient and the thermal shock resistance. In addition, the reliability under high temperature and high humidity, that is, the so-called humidity resistance load characteristic also has a problem that when the thickness of the dielectric layer is small and the dielectric layers are stacked, the dielectric layer similarly deteriorates.

In order to solve such a problem, Japanese Patent Publication No. 7-56850 discloses an aluminosilicate layer for forming Ni.
A multilayer ceramic capacitor in which an internal electrode and a ceramic are joined is disclosed. However, in this method, the capacitance decreases and the equivalent series resistance increases. Further, when the dielectric layer is thin, there is a problem that characteristics are deteriorated due to diffusion of Si or Al added to the internal electrode paste into the ceramic to form the aluminosilicate layer, and heat shock resistance is poor. Has no effect.

Japanese Patent Application Laid-Open No. 3-133114 discloses that Mn, P, F having a composition different from that of a dielectric layer is provided around an internal electrode.
A multilayer ceramic capacitor characterized by forming an oxide layer containing e or the like is disclosed. In this method, heat treatment is performed after firing in a low oxygen concentration for the purpose of improving reliability in a high temperature load test. However, this method has no effect on thermal shock resistance or moisture resistance load test characteristics. .

Accordingly, an object of the present invention is to provide a multilayer ceramic capacitor having improved thermal shock resistance and moisture resistance load characteristics by improving the dielectric layer of the multilayer ceramic capacitor having a base metal internal electrode.

[0009]

In order to achieve the above object, a multilayer ceramic capacitor according to the present invention comprises a plurality of dielectric ceramic layers and a plurality of internal layers mainly composed of a base metal formed between the dielectric ceramic layers. In a multilayer ceramic capacitor including an electrode and an external electrode electrically connected to the internal electrode, a metal whose concentration gradually decreases from an interface between the internal electrode and the dielectric ceramic layer toward the inside of the dielectric ceramic layer. It is characterized by the presence of an oxide.

The method for manufacturing a multilayer ceramic capacitor according to the present invention includes the following steps: (1) a first step of preparing a ceramic green sheet; and (2) a first step of forming a metal compound on the ceramic green sheet. A second step of forming a first layer; (3) a third step of forming an internal electrode layer mainly composed of a base metal on the first layer; and (4) a step of covering the internal electrode layer so as to cover the internal electrode layer. A fourth step of forming a second layer containing a metal compound, (5) a fifth step of laminating the ceramic green sheets to form a molded body, and (6) firing and sintering the molded body in a reducing atmosphere. And (7) a seventh step of forming an external electrode on the internal electrode exposed portion of the sintered body.

The metal oxide is Ba, Ca, M
It is characterized by being at least one of oxides of g, Zr and Hf.

Further, the base metal is Ni or a Ni alloy.

Further, the first layer or the second layer containing the metal compound is formed by a screen printing method.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS First, a multilayer ceramic capacitor according to the present invention will be described with reference to the drawings. FIG. 1 is a sectional view showing an example of the multilayer ceramic capacitor of the present invention, FIG. 2 is a plan view showing a dielectric ceramic layer portion having internal electrodes in the multilayer ceramic capacitor of FIG. 1, and FIG. FIG. 3 is an exploded perspective view showing a ceramic laminate portion of the capacitor. As shown in FIG. 1, a multilayer ceramic capacitor 1 of the present invention has external electrodes 5 on both end surfaces of a ceramic laminate 3 obtained by laminating a plurality of dielectric ceramic layers 2a and 2b via internal electrodes 4. And, if necessary, a first plating layer 6 and a second plating layer 7 are formed.

Next, a method of manufacturing a multilayer ceramic capacitor according to the present invention will be described in the order of steps with reference to FIGS. First, a non-reducible dielectric material powder is prepared as a raw material of a dielectric ceramic. Thereafter, an organic binder is added to the material powder to form a slurry, and the slurry is formed into a sheet shape to form ceramic green sheets (dielectric ceramic layers 2a and 2a).
Obtain b).

Next, a first surface containing a metal compound is formed on one surface of the ceramic green sheet (dielectric ceramic layer 2b).
(Not shown) is formed. As the metal compound, compounds such as Ba, Ca, Mg, Zr, and Hf are preferable. As a method for forming the layer containing the metal compound, a screen printing method, a spray method, a vapor deposition method, a plating method, or the like is used, but the screen printing method is preferable from the viewpoint of mass productivity.

Thereafter, an internal electrode layer 4 containing a base metal is formed on the first layer containing the metal compound. As a material for the internal electrode layer, nickel or a nickel alloy is used. In addition, as a method of forming the internal electrode layer 4, a screen printing method, an evaporation method, a plating method, or the like is used.

Thereafter, a second layer (not shown) containing a metal compound is formed so as to cover internal electrode layer 4. As the kind of the metal compound and the method for forming the same, the same material and method as those of the first layer containing the metal compound are used.

Thereafter, a required number of green sheets (dielectric ceramic layers 2b) having the internal electrode layers 4 are laminated and, as shown in FIG. 3, sandwiched between green sheets (dielectric ceramic layers 2a) having no internal electrodes and crimped. To form a molded body. Then, the compact is fired at a predetermined temperature in a reducing atmosphere to obtain a sintered body 3.

Next, a pair of external electrodes 5 are formed on both end surfaces of the sintered body 3 so as to be electrically connected to the internal electrode layers 4. As the material of the external electrode 5, the same material as that of the internal electrode layer 3 can be used. Ag, Pd, Ag-
A Pd alloy or the like can also be used. In general, the external electrode 5 is formed by applying a metal powder paste as a material to the ceramic laminate 3 obtained by firing and baking the applied ceramic powder. It can also be formed at the same time.

Finally, a first plating layer 6 and a second plating layer 7 are formed on the external electrodes 5 as necessary.
The multilayer ceramic capacitor 1 is completed.

[0022]

EXAMPLES (Example 1) First, TiC was used as a starting material.
It was weighed to prepare a l ₄ and Ba (NO _{3) 2,} from the state of the mixed solution, barium titanyl oxalate by oxalate (BAT
It was precipitated as _{iO (C 2 O 4) ·} 4H 2 O). Thereafter, the precipitate was thermally decomposed at a temperature of 1000 ° C. or higher to obtain a barium titanate (Ba: Ti molar ratio: 1.0).
TiO ₃ ) was obtained.

Next, BaCO ₃ for adjusting the Ba / Ti molar ratio of barium titanate, and Y ₂ having a purity of 99% or more.
O ₃ , Dy ₂ O ₃ , MnCO ₃ , NiO, Co ₂ O ₃ and M
gO was prepared. And 97.0 of these raw material powders
{BaO} _1.010・ TiO ₂ + 0.7Y ₂ O ₃ + 0.3Dy
_It was weighed so as to have a composition ratio of ₂ O ₃ +0.6 MnO + 0.7NiO + 0.7CoO (molar ratio). Next, based on the mixture, 1.2 mol% of MgO and Li ₂ O—
After adding 1.5 wt% of a glass powder mainly composed of (TiO ₂ .SiO ₂ ) —Al ₂ O ₃ , an organic solvent such as a polyvinyl butyral-based binder and ethanol was added, and the mixture was wet-mixed with a ball mill to obtain a ceramic slurry. Was prepared. Thereafter, a sheet was formed by a doctor blade method using the ceramic slurry to obtain a rectangular ceramic green sheet having a thickness of 11 μm.

Then, on the ceramic green sheet, as a first layer containing a metal compound, the average particle diameter is 1 μm.
A paste consisting of up to m m of CaCO ₃ powder and an organic vehicle was printed and dried. On top of this, a paste mainly composed of Ni was printed and dried as an internal electrode layer containing a base metal. After that, as a second layer containing a metal compound, CaC having an average particle diameter of 1 μm or less is formed so as to cover the internal electrode layer.
A paste consisting of O ₃ powder and an organic vehicle was printed and dried.

Next, a plurality of ceramic green sheets on which the first layer containing the metal compound, the internal electrode layer, and the second layer containing the metal compound are formed are arranged such that the side from which the internal electrode layer is drawn out is alternated. The sheets were laminated to obtain a molded body.
After removing the binder at a temperature of 350 ° C. in an N ₂ atmosphere, the formed body was fired in a reducing atmosphere composed of H ₂ —N ₂ —H ₂ O gas to obtain a sintered body. The firing was maintained at 1300 ° C. for 2 hours, and both the rate of temperature rise and the rate of cooling were 200 ° C./hour.

Thereafter, a silver paste was applied to the exposed portions of the internal electrodes of the obtained sintered body, and the paste was heated to 600 ° C. in an N ₂ atmosphere.
To form external electrodes electrically connected to the internal electrodes. Thereafter, a Ni plating film was formed on the external electrodes, and a solder plating film was formed on the Ni plating film.

The outer dimensions of the multilayer ceramic capacitor thus obtained are as follows: width: 1.6 mm, length: 3.2
mm, thickness: 1.2 mm, the thickness of the dielectric ceramic layer interposed between the internal electrodes was 6 μm, and the total number of effective dielectric ceramic layers was 150 layers.

Further, as Comparative Example 1, a multilayer ceramic capacitor was produced in the same manner as in the above-mentioned Example except that neither the first layer nor the second layer made of a metal compound was formed.

Next, these multilayer ceramic capacitors were subjected to a thermal shock resistance test and a moisture resistance load test. For the thermal shock resistance test, 50 pieces of each sample, 300
After immersion for 2 to 3 seconds in a solder bath at a temperature of 325 ° C. or 325 ° C., the surface of the ceramic and the inside of the ceramic exposed by polishing were observed with a microscope to check for cracks. For the moisture resistance load test, 72
A DC voltage of 16 V was continuously applied at a pressure of 2 atmospheres (100% relative humidity) and a temperature of 121 ° C., and a sample having an insulation resistance (IR) of 10 ⁶ Ω or less by the time 250 hours had passed was determined to be defective.

The dielectric layer is made of EPMA (Electron Pro
be Micro Analysis (electron beam microanalysis method) to determine whether there is a metal oxide whose concentration gradually decreases from the interface between the internal electrode and the dielectric ceramic layer and into the dielectric ceramic layer. Confirmation was made. Table 1 shows the results of the above evaluation.

[0031]

[Table 1]

As shown in Table 1, the sample of Example 1 in which a paste composed of CaCO ₃ powder and an organic vehicle was printed to form a first layer and a second layer composed of a metal compound was subjected to EPMA analysis. As a result, from the interface between the internal electrode and the dielectric ceramic layer, into the dielectric ceramic layer,
The presence of Ca oxides of decreasing concentration was observed. Regarding the thermal shock resistance test and the moisture resistance load test,
For the sample of Example 1, no defect occurred.

On the other hand, the sample of Comparative Example 1 in which the presence of Ca oxide whose concentration was gradually decreased was not recognized,
Defectiveness occurred in both the thermal shock resistance test and the moisture resistance load test.

From the above results, as in the present invention, the presence of Ca oxide having a gradually decreasing concentration from the interface between the internal electrode and the dielectric ceramic layer toward the inside of the dielectric ceramic layer is considered to be due to heat resistance. It is evident that it is effective in improving the impact resistance and the reliability in the moisture resistance load test.

Example 2 First, as starting materials, SrCO ₃ , ZrO ₂ and TiO ₂ having a purity of 99% or more were prepared, and these raw material powders were SrO · (Zr _0.95 Ti _0.05 ).
It was weighed so as to have a composition ratio of O ₂ . Next, water was added to these raw materials and wet-mixed by a ball mill. The obtained slurry was evaporated and dried, and calcined at a temperature of 1100 ° C. or higher to obtain a main component.

Next, 1.2 parts by weight of ZnO having a purity of 99% or more and 100 parts by weight of
After adding 1.5 parts by weight of a glass powder mainly composed of ₂ O- (TiO ₂ .SiO ₂ ) -Al ₂ O ₃ , an organic solvent such as a polyvinyl butyral-based binder and ethanol is added, and wet mixing is performed by a ball mill. Then, a ceramic slurry was prepared. Then, using a ceramic slurry, a sheet is formed by a doctor blade method to a thickness of 11 mm.
A rectangular ceramic green sheet of μm was obtained.

Then, on the ceramic green sheet, as a first layer containing a metal compound, the average particle diameter is 1 μm.
A paste consisting of less than m BaCO ₃ powder and an organic vehicle was printed and dried. On top of this, a paste mainly composed of Ni was printed and dried as an internal electrode layer containing a base metal. Then, as a second layer containing a metal compound, a BaC having an average particle diameter of 1 μm or less is formed so as to cover the internal electrode layer.
A paste consisting of O ₃ powder and an organic vehicle was printed and dried.

Next, a plurality of ceramic green sheets on which the first layer containing the metal compound, the internal electrode layer, and the second layer containing the metal compound are formed are arranged such that the side from which the internal electrode layer is drawn out is alternated. The sheets were laminated to obtain a laminate.
After removing the binder at a temperature of 350 ° C. in an N ₂ atmosphere, the laminate was fired in a reducing atmosphere composed of H ₂ —N ₂ —H ₂ O gas to obtain a sintered body. The firing was maintained at 1150 ° C. for 2 hours, and both the rate of temperature rise and the rate of cooling were 200 ° C./hour.

Thereafter, a multilayer ceramic capacitor was manufactured in the same manner as in Example 1. The external dimensions of the multilayer ceramic capacitor thus obtained are: width: 1.6 m
m, length: 3.2 mm, thickness: 1.2 mm, the thickness of the dielectric ceramic layer interposed between the internal electrodes was 6 μm, and the total number of effective dielectric ceramic layers was 150.

Further, as Comparative Example 2, a multilayer ceramic capacitor was manufactured in the same manner as in the above Example, except that neither the first layer nor the second layer made of a metal compound was formed.

Next, a thermal shock resistance test and a moisture resistance load test were performed on these multilayer ceramic capacitors in the same manner as in Example 1. In addition, the dielectric layer was analyzed by EPMA in the same manner as in Example 1, and there was a metal oxide whose concentration gradually decreased from the interface between the internal electrode and the dielectric ceramic layer toward the inside of the dielectric ceramic layer. Confirmed whether or not. Table 2 shows the results of the above evaluation.

[0042]

[Table 2]

As shown in Table 2, the sample of Example 2 in which the paste composed of BaCO ₃ powder and the organic vehicle was printed to form the first layer and the second layer composed of the metal compound was subjected to the EPMA analysis. As a result, from the interface between the internal electrode and the dielectric ceramic layer, into the dielectric ceramic layer,
The presence of a Ba oxide with a gradually decreasing concentration was observed. Regarding the thermal shock resistance test and the moisture resistance load test,
For the sample of Example 2, no defect occurred.

On the other hand, for the sample of Comparative Example 2 in which the presence of the Ba oxide whose concentration was gradually decreased was not recognized,
Defectiveness occurred in both the thermal shock resistance test and the moisture resistance load test.

From the above results, as in the present invention, the presence of Ba oxide having a gradually decreasing concentration from the interface between the internal electrode and the dielectric ceramic layer toward the dielectric ceramic layer is considered to be due to heat resistance. It is evident that it is effective in improving the impact resistance and the reliability in the moisture resistance load test.

Example 3 First, as starting materials, SrCO ₃ , ZrO ₂ and TiO ₂ having a purity of 99% or more were prepared, and these raw material powders were SrO · (Zr _0.95 Ti _0.05 ).
It was weighed so as to have a composition ratio of O ₂ . Next, water was added to these raw materials and wet-mixed by a ball mill. The obtained slurry was evaporated and dried, and calcined at a temperature of 1100 ° C. or higher to obtain a main component.

Next, with respect to 100 parts by weight of the main component powder, 1.2 parts by weight of ZnO having a purity of 99% or more and L1
After adding 1.5 parts by weight of a glass powder mainly composed of ₂ O- (TiO ₂ .SiO ₂ ) -Al ₂ O ₃ , an organic solvent such as a polyvinyl butyral-based binder and ethanol is added, and wet mixing is performed by a ball mill. Then, a ceramic slurry was prepared. Then, using a ceramic slurry, a sheet is formed by a doctor blade method to a thickness of 11 mm.
A μm rectangular ceramic green sheet was obtained.

Thereafter, on the ceramic green sheet, as a first layer containing a metal compound, the average particle diameter was 1 μm.
A paste consisting of less than m MgCO ₃ powder and an organic vehicle was printed and dried. On top of this, a paste mainly composed of Ni was printed and dried as an internal electrode layer containing a base metal. Thereafter, as a second layer containing a metal compound, MgCO ₃ having an average particle size of 1 μm or less is formed so as to cover the internal electrodes.
The paste consisting of the powder and the organic vehicle was printed and dried.

Next, a plurality of ceramic green sheets on which the first layer containing the metal compound, the internal electrode layer, and the second layer containing the metal compound are formed are arranged such that the side from which the internal electrode layer is drawn out is alternated. The sheets were laminated to obtain a laminate.
After removing the binder at a temperature of 350 ° C. in an N ₂ atmosphere, the laminate was fired in a reducing atmosphere composed of H ₂ —N ₂ —H ₂ O gas to obtain a sintered body. The firing was maintained at 1150 ° C. for 2 hours, and both the rate of temperature rise and the rate of cooling were 200 ° C./hour.

Thereafter, a multilayer ceramic capacitor was manufactured in the same manner as in Example 1. The external dimensions of the multilayer ceramic capacitor thus obtained are: width: 1.6 m
m, length: 3.2 mm, thickness: 1.2 mm, the thickness of the dielectric ceramic layer interposed between the internal electrodes was 6 μm, and the total number of effective dielectric ceramic layers was 150.

Further, as Comparative Example 3, a multilayer ceramic capacitor was produced in the same manner as in the above Example, except that neither the first layer nor the second layer made of a metal compound was formed.

Next, a thermal shock resistance test and a moisture resistance load test were performed on these multilayer ceramic capacitors in the same manner as in Example 1. In addition, the dielectric layer was analyzed by EPMA in the same manner as in Example 1, and there was a metal oxide whose concentration gradually decreased from the interface between the internal electrode and the dielectric ceramic layer toward the inside of the dielectric ceramic layer. Confirmed whether or not. Table 3 shows the results of the above evaluation.

[0053]

[Table 3]

As shown in Table 3, the sample of Example 3 in which the paste composed of the MgCO ₃ powder and the organic vehicle was printed to form the first layer and the second layer composed of the metal compound was subjected to the EPMA analysis. As a result, from the interface between the internal electrode and the dielectric ceramic layer, into the dielectric ceramic layer,
The presence of Mg oxide with a gradual decrease in concentration was observed. Regarding the thermal shock resistance test and the moisture resistance load test,
For the sample of Example 3, no defect occurred.

On the other hand, for the sample of Comparative Example 3 in which the presence of Mg oxide having a gradually decreasing concentration was not recognized,
Defectiveness occurred in both the thermal shock resistance test and the moisture resistance load test.

From the above results, it can be seen that the presence of Mg oxide whose concentration gradually decreases from the interface between the internal electrode and the dielectric ceramic layer toward the dielectric ceramic layer as in the present invention indicates that the heat resistance is high. It is evident that it is effective in improving the impact resistance and the reliability in the moisture resistance load test.

Example 4 First, Ti was used as a starting material.
After preparing and weighing Cl ₄ and Ba (NO ₃ ) ₂ , titanyl barium oxalate (Ba) was mixed with oxalic acid from the mixed solution.
It was precipitated as _{TiO (C 2 O 4) ·} 4H 2 O). Thereafter, the precipitate was thermally decomposed at a temperature of 1000 ° C. or higher to obtain a barium titanate (Ba: Ti molar ratio: 1.0).
TiO ₃ ) was obtained.

Next, Ho ₂ O ₃ , Co ₂
O ₃ , BaCO ₃ , MnCO ₃ , MgO and SiO ₂ were prepared. Then, these raw material powders are mixed with 96.5BaTi
_{O 3 + 1.5Ho 2 O 3 +} 2.0Co 2 O 3 were weighed so that the composition ratio (molar ratio). Then, the mixture 10
0.5 mol of BaO and 1.5 mol of MnO with respect to 0 mol.
After adding 2.0 mol of MgO, 2.0 mol of MgO and 2.0 mol of SiO ₂ , an organic solvent such as a polyvinyl butyral-based binder and ethanol were added, and the mixture was wet-mixed with a ball mill to prepare a ceramic slurry. Thereafter, a sheet was formed from the ceramic slurry by a doctor blade method to obtain a rectangular ceramic green sheet having a thickness of 11 μm.

Then, on the ceramic green sheet, as a first layer containing a metal compound, the average particle diameter was 1 μm.
A paste consisting of ZrO ₂ powder of up to m and an organic vehicle was printed and dried. On top of this, a paste mainly composed of Ni was printed and dried as an internal electrode layer containing a base metal. Thereafter, a paste made of a ZrO ₂ powder having an average particle diameter of 1 μm or less and an organic vehicle was printed and dried as a second layer containing a metal compound so as to cover the internal electrode layer.

Next, a plurality of ceramic green sheets on which the first layer containing the metal compound, the internal electrode layer, and the second layer containing the metal compound are formed are arranged such that the side from which the internal electrode layer is drawn out is alternated. The sheets were laminated to obtain a molded body.
After removing the binder at a temperature of 350 ° C. in an N ₂ atmosphere, the formed body was fired in a reducing atmosphere composed of H ₂ —N ₂ —H ₂ O gas to obtain a sintered body. The firing was maintained at 1300 ° C. for 2 hours, and both the rate of temperature rise and the rate of cooling were 200 ° C./hour.

Thereafter, a multilayer ceramic capacitor was manufactured in the same manner as in Example 1. The external dimensions of the multilayer ceramic capacitor thus obtained are: width: 1.6 m
m, length: 3.2 mm, thickness: 1.2 mm, the thickness of the dielectric ceramic layer interposed between the internal electrodes was 6 μm, and the total number of effective dielectric ceramic layers was 150.

As Comparative Example 4, a multilayer ceramic capacitor was manufactured in the same manner as in the above Example, except that neither the first layer nor the second layer made of a metal compound was formed.

Next, a thermal shock resistance test and a moisture resistance load test were performed on these multilayer ceramic capacitors in the same manner as in Example 1. In addition, the dielectric layer was analyzed by EPMA in the same manner as in Example 1, and there was a metal oxide whose concentration gradually decreased from the interface between the internal electrode and the dielectric ceramic layer toward the inside of the dielectric ceramic layer. Confirmed whether or not. Table 4 shows the results of the above evaluations.

[0064]

[Table 4]

As shown in Table 4, the paste of ZrO ₂ powder and the organic vehicle was printed to form the first layer and the second layer made of the metal compound. As a result, the presence of the Zr oxide whose concentration gradually decreased from the interface between the internal electrode and the dielectric ceramic layer toward the inside of the dielectric ceramic layer was recognized.
Regarding the thermal shock resistance test and the moisture resistance load test, no defect occurred in the sample of Example 4.

On the other hand, for the sample of Comparative Example 4 in which the presence of the Zr oxide whose concentration was gradually decreased was not recognized,
Defectiveness occurred in both the thermal shock resistance test and the moisture resistance load test.

From the above results, it can be seen that the presence of the Zr oxide whose concentration gradually decreases from the interface between the internal electrode and the dielectric ceramic layer toward the dielectric ceramic layer as in the present invention, It is evident that it is effective in improving the impact resistance and the reliability in the moisture resistance load test.

Example 5 First, Ti was used as a starting material.
After preparing and weighing Cl ₄ and Ba (NO ₃ ) ₂ , titanyl barium oxalate (Ba) was mixed with oxalic acid from the mixed solution.
It was precipitated as _{TiO (C 2 O 4) ·} 4H 2 O). Thereafter, the precipitate is thermally decomposed at a temperature of 1000 ° C. or higher to obtain a barium titanate (BaT) having a Ba / Ti molar ratio of 1.0.
iO ₃ ) was obtained.

Next, Ho ₂ O ₃ , Co ₂
O ₃ , BaCO ₃ , MnCO ₃ , MgO and SiO ₂ were prepared. Then, these raw material powders are mixed with 96.5BaTi
_{O 3 + 1.5Ho 2 O 3 +} 2.0Co 2 O 3 were weighed so that the composition ratio (molar ratio). Then, the mixture 10
0.5 mol of BaO and 1.5 mol of MnO with respect to 0 mol.
After adding 2.0 mol of MgO, 2.0 mol of MgO and 2.0 mol of SiO ₂ , an organic solvent such as a polyvinyl butyral-based binder and ethanol were added, and the mixture was wet-mixed with a ball mill to prepare a ceramic slurry. Thereafter, a sheet was formed from the ceramic slurry by a doctor blade method to obtain a rectangular ceramic green sheet having a thickness of 11 μm.

Then, on the ceramic green sheet, as a first layer containing a metal compound, the average particle size was 1 μm.
A paste consisting of HfO ₂ powder of less than m and an organic vehicle was printed and dried. On top of this, a paste mainly composed of Ni was printed and dried as an internal electrode layer containing a base metal. Thereafter, a paste composed of HfO ₂ powder having an average particle diameter of 1 μm or less and an organic vehicle was printed and dried as a second layer containing a metal compound so as to cover the internal electrode layer.

Next, a plurality of ceramic green sheets on which the first layer containing the metal compound, the internal electrode layer, and the second layer containing the metal compound are formed are arranged such that the side from which the internal electrode layers are drawn out is alternated. The sheets were laminated to obtain a molded body.
After removing the binder at a temperature of 350 ° C. in an N ₂ atmosphere, the formed body was fired in a reducing atmosphere composed of H ₂ —N ₂ —H ₂ O gas to obtain a sintered body. The firing was maintained at 1300 ° C. for 2 hours, and both the rate of temperature rise and the rate of cooling were 200 ° C./hour.

Thereafter, a multilayer ceramic capacitor was manufactured in the same manner as in Example 1. The external dimensions of the multilayer ceramic capacitor thus obtained are: width: 1.6 m
m, length: 3.2 mm, thickness: 1.2 mm, the thickness of the dielectric ceramic layer interposed between the internal electrodes was 6 μm, and the total number of effective dielectric ceramic layers was 150.

As Comparative Example 5, a multilayer ceramic capacitor was manufactured in the same manner as in the above Example, except that neither the first layer nor the second layer made of a metal compound was formed.

Next, a thermal shock resistance test and a moisture resistance load test were performed on these multilayer ceramic capacitors in the same manner as in Example 1. In addition, the dielectric layer was analyzed by EPMA in the same manner as in Example 1, and there was a metal oxide whose concentration gradually decreased from the interface between the internal electrode and the dielectric ceramic layer toward the inside of the dielectric ceramic layer. Confirmed whether or not. Table 5 shows the results of the above evaluation.

[0075]

[Table 5]

As shown in Table 5, the paste of HfO ₂ powder and the organic vehicle was printed to form the first layer and the second layer made of a metal compound. As a result, the presence of the Hf oxide whose concentration gradually decreased from the interface between the internal electrode and the dielectric ceramic layer toward the inside of the dielectric ceramic layer was recognized.
Further, regarding the thermal shock resistance test and the moisture resistance load test, no defect occurred in the sample of Example 5.

On the other hand, for the sample of Comparative Example 5 in which the presence of the Hf oxide whose concentration was gradually decreased was not recognized,
Defectiveness occurred in both the thermal shock resistance test and the moisture resistance load test.

From the above results, it can be seen that the presence of the Hf oxide whose concentration gradually decreases from the interface between the internal electrode and the dielectric ceramic layer toward the dielectric ceramic layer as in the present invention indicates that the heat resistance is high. It is evident that it is effective in improving the impact resistance and the reliability in the moisture resistance load test.

[0079]

As is apparent from the above description, the multilayer ceramic capacitor of the present invention has an internal electrode containing a base metal as a main component, and the inside of the dielectric ceramic layer extends from the interface between the internal electrode and the dielectric ceramic layer. , Metal oxides of decreasing concentration are present around the internal electrodes.

By adopting such a configuration, a multilayer ceramic capacitor having excellent properties of thermal shock resistance and moisture load resistance can be obtained.

[Brief description of the drawings]

FIG. 1 is a sectional view showing an example of a multilayer ceramic capacitor of the present invention.

FIG. 2 is a plan view showing a dielectric ceramic layer portion having an internal electrode in the multilayer ceramic capacitor of FIG. 1;

FIG. 3 is an exploded perspective view showing a ceramic laminate portion of the multilayer ceramic capacitor of FIG. 1;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Multilayer ceramic capacitor 2a, 2b Dielectric ceramic layer 3 Ceramic multilayer body 4 Internal electrode 5 External electrode 6, 7 Plating layer

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Takeshi Yamana 2-26-10 Tenjin, Nagaokakyo-shi, Kyoto Inside Murata Manufacturing Co., Ltd.

Claims (7)

[Claims] 1. A semiconductor device comprising: a plurality of dielectric ceramic layers; a plurality of internal electrodes mainly composed of a base metal formed between the dielectric ceramic layers; and external electrodes electrically connected to the internal electrodes. In the multilayer ceramic capacitor, a metal oxide whose concentration gradually decreases from an interface between the internal electrode and the dielectric ceramic layer toward the inside of the dielectric ceramic layer is present. 2. The method according to claim 1, wherein the metal oxide is Ba, Ca, Mg, Z
The multilayer ceramic capacitor according to claim 1, wherein the multilayer ceramic capacitor is at least one of oxides of r and Hf. 3. The multilayer ceramic capacitor according to claim 1, wherein the base metal is Ni or a Ni alloy. 4. A method for manufacturing a multilayer ceramic capacitor including the following steps: (1) a first step for producing a ceramic green sheet; and (2) forming a first layer containing a metal compound on the ceramic green sheet. The second step,
(3) a third step of forming an internal electrode layer mainly composed of a base metal on the first layer; (4) forming a second layer containing the metal compound so as to cover the internal electrode layer (5) a fifth step of laminating the ceramic green sheets to form a compact, (6) a sixth step of firing the compact in a reducing atmosphere to form a sintered body, (7) A seventh step of forming an external electrode on the internal electrode exposed portion of the sintered body. 5. The method according to claim 1, wherein the metal compound is Ba, Ca, Mg, Z.
The method for manufacturing a multilayer ceramic capacitor according to claim 4, wherein the compound is at least one of compounds of r and Hf. 6. The method according to claim 4, wherein the base metal is Ni or a Ni alloy. 7. The multilayer ceramic capacitor according to claim 4, wherein the first layer or the second layer containing the metal compound is formed by a screen printing method. Method.