JP2000058377A - Laminated ceramic capacitor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enhance reliability by constituting a dielectric ceramic layer of a laminated ceramic capacitor from a dielectric porcelain composite, that will not be reduced even if it is fired in a reducing environment. SOLUTION: A laminated ceramic capacitor 1 is prepared by forming outer electrodes 5 and plated layers 6 and 7 on both ends of a laminated ceramic body 3, which is laminated with plural dielectric ceramic layers 2a and 2b with inner electrodes 4 putting inside. The dielectric ceramic layers 2a and 2b have barium calcium titanate Ba1-xCaO}mTiO2, more than one kinds from among Y2O3, Gd2O3, Tb2O3, Dy2O3, Ho2O3, Er2O3 and Yb2O3, and MgO and MnO as main components, and contain either an oxide of Li2O-(Si,Ti)O2-MO based (MO is one kind from Al2O3 or ZiO2), or an oxide of SiO2-TiO2-XO based (XO is one kind from among BaO, CaO, a SrO, MgO, ZnO and MnO) as a sub constituent. The inner electrodes 4 are constituted of Ni or a Ni alloy.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a multilayer ceramic capacitor for use in electronic equipment, and
The present invention relates to a multilayer ceramic capacitor having internal electrodes made of a nickel alloy.

[0002]

2. Description of the Related Art A multilayer ceramic capacitor is formed by laminating a ceramic element and an internal electrode metal. Recently, an expensive noble metal, A, has been used for internal electrodes to reduce costs.
Inexpensive base metal Ni has been used in place of g and Pd. When Ni is used for the electrode, it is necessary to fire in a reducing atmosphere in which Ni is not oxidized. By firing in a reducing atmosphere, the ceramic made of barium titanate is originally reduced to a semiconductor. However,
For example, since the non-reducing technology of a dielectric material in which the ratio of barium site / titanium site in a barium titanate solid solution was made to be higher than the stoichiometric ratio as disclosed in JP-B-57-42588, was invented. And a multilayer ceramic capacitor using Ni as an electrode can be put to practical use, and the production volume thereof is expanding.

[0003]

With the development of electronics in recent years, the miniaturization of electronic components has rapidly progressed, and the tendency of multilayer ceramic capacitors to be smaller and have a larger capacity has been remarkable. In addition, these multilayer ceramic capacitors are required to have a small size and a large capacity, and also to have a temperature stability of an electrostatic capacitance. To date, the development of ceramic materials for multilayer ceramic capacitors has been required to have a good temperature characteristic of a dielectric constant and a high dielectric constant. The emphasis was on having a dielectric constant. Many materials have been proposed and put into practical use as high dielectric constant materials having good temperature characteristics. These have a dielectric constant of 3
It is a high material of over 000. The provision of these materials has made it possible to produce a high-capacity monolithic ceramic capacitor with a small temperature change in capacitance, which has greatly contributed to market expansion.

However, in recent years, there has been an increasing demand for further miniaturization and large capacity, and it has become necessary to further reduce the thickness of the dielectric ceramic layer and increase the number of layers. However, the thinning of the layer causes a high electric field strength voltage to be applied to the dielectric, which causes disadvantages such as a decrease in the dielectric constant, a deterioration in the temperature characteristics, and a decrease in the reliability of the conventional material. This has been a major obstacle to increasing the capacity of the multilayer ceramic capacitor. In particular, when the thickness of the dielectric layer of the multilayer ceramic capacitor is reduced to 5 μm or less, the number of ceramic particles between the internal electrodes is reduced to about 10 or less, and the reliability is significantly reduced. Had occurred. For this reason, there is a demand for the development of a material that is highly reliable and that has excellent stability against the electric field strength of the dielectric constant.

Therefore, an object of the present invention is to reduce the dielectric constant even when a high voltage is applied by making the dielectric ceramic layer thin, and to provide a stable capacitance under an actual high electric field. Provided is a high-capacity multilayer ceramic capacitor with a thin dielectric ceramic layer that satisfies the B characteristic specified by the JIS standard and the X7R characteristic specified by the EIA standard. Is to do.

[0006]

In order to achieve the above object, a multilayer ceramic capacitor according to the present invention comprises: a plurality of dielectric ceramic layers; an internal electrode formed between the dielectric ceramic layers; Wherein the dielectric ceramic layer has the following composition formula: {Ba _{1 -x} Ca _x O} _m TiO ₂ + αRe ₂ O ₃ + βMgO +
γMnO (where Re ₂ O ₃ is Y ₂ O ₃ , Gd ₂ O ₃ , Tb ₂ O ₃ , D
and the _{y 2 O 3, Ho 2 O} 3, Er 2 O 3 and Yb ₂ O ₃ of at least one or more selected from among, alpha, beta and γ represent mole ratios, 0.001 ≦ α ≦ 0. 10, 0.001 ≦ β
≦ 0.12, 0.001 <γ ≦ 0.12, 1.000 <
m ≦ 1.035, 0.005 <x ≦ 0.22), and alkali metal in {Ba _{1 -x} Ca _x O} TiO ₂ raw material used for the dielectric ceramic layer With respect to 100 parts by weight of the main component having an oxide content of 0.02% by weight or less, the first subcomponent is Li ₂ O— (Si, T
i) an oxide of an O ₂ -MO system (where MO is at least one selected from Al ₂ O ₃ and ZrO ₂ );
The second subcomponent is a SiO ₂ —TiO ₂ —XO system (XO is Ba
O, CaO, SrO, MgO, at least one selected from ZnO and MnO) when one of the first or second subcomponent is 0.2 to 0.2
The internal electrode is made of nickel or a nickel alloy.

Further, ΔB used for the dielectric ceramic layer
The average particle size of the a _1-x Ca _x O｝ TiO ₂ raw material is 0.1 to
It is 0.7 μm.

The first subcomponent is xLi ₂ O-y
When represented by (Si _w Ti _1-w ) O ₂ -zMO (where x, y and z are mol%, and w is in the range of 0.30 ≦ w ≦ 1.0), A (x = 20, y = 80, z = 0), B (x
= 10, y = 80, z = 10), C (x = 10, y = 7)
0, z = 20), D (x = 35, y = 45, z = 2)
0), E (x = 45, y = 45, z = 10), F (x =
45, y = 55, z = 0) (however, in the case of the composition on the straight line AF, w is within a range of 0.3 ≦ w <1.0) and is surrounded by a straight line connecting points. Characterized in that it is located inside or on a line of the specified area.

The second subcomponent is xSiO ₂ -y
When expressed in a TiO ₂ -zXO system (where x, y and z are mol%), A (x = 85, y = 1, z = 14) ), B (x
= 35, y = 51, z = 14), C (x = 30, y = 2)
0, z = 50) and D (x = 39, y = 1, z = 60) are inside or on a line surrounded by a straight line connecting points.

In the second subcomponent, the SiO 2
_For 100 parts by weight of the _2- TiO ₂ —XO-based oxide, A
at least one of l ₂ O ₃ and ZrO _{2 in} a total of 15
It is characterized by containing not more than 5 parts by weight (however, not more than 5 parts by weight of ZrO ₂ ).

Further, the external electrode is formed of a sintered layer of a conductive metal powder or a conductive metal powder to which glass frit is added.

Further, the external electrode comprises a sintered layer of a conductive metal powder or a conductive metal powder to which glass frit is added, and a plating layer formed thereon.

[0013]

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.

The dielectric ceramic layers 2a and 2b are made of barium calcium titanate {Ba _{1 -x} Ca _x O} _m TiO ₂ ;
Y ₂ O ₃ , Gd ₂ O ₃ , Tb ₂ O ₃ , Dy ₂ O ₃ , Ho ₂ O ₃ , E
At least one selected from r ₂ O ₃ and Yb ₂ O ₃ , MgO and MnO as main components, and Li ₂ O— (Si, Ti) O ₂ —MO system (MO is Al
Oxides of at least one selected from ₂ O ₃ and ZrO ₂ , or SiO ₂ —TiO ₂ —XO-based (XO is Ba)
O, CaO, SrO, MgO, ZnO and MnO) (at least one selected from oxides). Thus, even when firing in a reducing atmosphere, firing can be performed without forming a semiconductor, and the temperature characteristic of the capacitance is reduced according to JIS.
B characteristic specified by the standard and X7R specified by the EIA standard
A multilayer ceramic capacitor that satisfies the characteristics, has high insulation resistance at room temperature and high temperature, has high reliability, and has excellent dielectric strength can be obtained.

Here, by using a barium calcium titanate material having an average particle size of 0.1 to 0.7 μm, even if the dielectric ceramic layer is thin and the electric field strength is high, the electric field of the dielectric constant can be reduced. Little change,
Further, a highly reliable multilayer ceramic capacitor can be obtained. Also, the dielectric ceramic has a Re component (however, Re
Has a core-shell structure in which at least one selected from the group consisting of Y, Gd, Tb, Dy, Ho, Er and Yb) exists near and at the grain boundaries due to diffusion during firing.

By using a barium calcium titanate having an alkali metal oxide content of 0.02% by weight or less such as Na ₂ O or K ₂ O, a highly reliable dielectric material can be obtained. Can be

The ratio (n) of (barium + calcium) / titanium as a barium calcium titanate raw material is not particularly limited. Considering the stability of powder raw material production, n
If 0.990 to 1.035, the variation in the particle size of the synthesized powder is preferably small.

Further, Li ₂ O—
125 (Si, Ti) O ₂ -MO based oxide
Sintering can be performed at a relatively low temperature of 0 ° C. or less, and high-temperature load characteristics are improved. In addition, S contained in the above main component
by iO ₂ -TiO ₂ -XO based oxides, along with sinterability is improved, thereby improving the high-temperature load characteristics and moisture load characteristics. Further, when the oxide of SiO ₂ —TiO ₂ —XO contains Al ₂ O ₃ and ZrO ₂ , higher insulation resistance can be obtained.

Next, the internal electrode 4 is made of nickel or a nickel alloy which is a base metal.

The external electrodes 5 are made of Ag, Pd, Ag-P
d, Cu, sintered layers of various conductive metals such as Cu alloys,
Alternatively, the conductive metal powder and B ₂ O ₃ —Li ₂ O—SiO ₂
—BaO, B ₂ O ₃ —SiO ₂ —BaO, Li ₂ O—S
It is constituted by a sintered layer in which various glass frit such as iO ₂ —BaO type, B ₂ O ₃ —SiO ₂ —ZnO type are mixed. And it is also possible to form a plating layer on this sintered layer. As this plating layer, Ni, C
Only the first plating layer 6 made of u, Ni—Cu alloy, or the like may be used, or a second plating layer 7 made of solder, tin, or the like may be further formed thereon.

Next, a method of manufacturing a multilayer ceramic capacitor according to the present invention will be described in the order of manufacturing steps with reference to FIGS. First, as a raw material for a dielectric ceramic, a raw material powder prepared by a solid phase method in which an oxide or a carbonate is reacted at a high temperature, or a raw material powder prepared by a wet synthesis method such as an alkoxide method or a hydrothermal method is prepared. I do. In addition, additives and the like, in addition to powders such as oxides and carbonates,
Solutions such as alkoxides and organic metals can also be used.

Thereafter, the prepared raw materials are weighed and mixed at a predetermined composition ratio, and then mixed with an organic binder to form a slurry, and formed into a sheet to obtain green sheets (dielectric ceramic layers 2a and 2b). Next, an internal electrode 4 made of nickel or a nickel alloy is formed on one surface of the green sheet (dielectric ceramic layer 2b). The method for forming the internal electrodes 4 may be screen printing or the like, or may be deposition or plating.

Thereafter, a required number of green sheets (dielectric ceramic layers 2b) having the internal electrodes 4 are laminated, and FIG.
As shown in (1), a green sheet (dielectric ceramic layer 2a) having no internal electrode is sandwiched and pressed to form a laminate.
Then, the laminate is fired at a predetermined temperature in a reducing atmosphere to obtain a ceramic laminate 3.

Then, on both end surfaces of the ceramic laminate 3,
A pair of external electrodes 5 are formed so as to be electrically connected to the internal electrodes 4. 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. 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, and the multilayer ceramic capacitor 1 is completed.

[0026]

EXAMPLES (Example 1) First, TiO ₂ as a starting material _,
BaCO ₃ and CaCO ₃ were prepared and mixed and pulverized.
By heating at a temperature of 000 ° C. or more, nine kinds of barium calcium titanates shown in Table 1 were synthesized. The particle size of the raw material was observed with a scanning electron microscope, and the average particle size was determined.

[0027]

[Table 1]

Also, 0.25Li ₂ O is used as the first subcomponent.
_{-0.65 (0.30TiO 2 · 0.70SiO 2)} -
0.10 Al ₂ O ₃ (molar ratio)
The oxides, carbonates and hydroxides of each component were weighed and mixed and pulverized to obtain a powder. Similarly, as the second subcomponent, 0.
66SiO ₂ -0.17TiO ₂ -0.15BaO-0.
Oxides, carbonates and hydroxides of the respective components were weighed so as to have a composition ratio of 02MnO (molar ratio) and mixed and pulverized to obtain a powder. Next, the powders of the first and second subcomponents are heated to 1500 ° C. in separate platinum crucibles, quenched, and pulverized, so that the average particle diameter is 1 μm.
m or less of each oxide powder was obtained.

Next, Ba for adjusting the (Ba, Ca) / Ti molar ratio m as barium calcium titanate is used.
CO ₃ or TiO ₂ , and Y ₂ O _{3 having} a purity of 99% or more,
Gd ₂ O ₃ , Tb ₂ O ₃ , Dy ₂ O ₃ , Ho ₂ O ₃ , Er ₂ O ₃ ,
Yb ₂ O ₃ , MgO and MnO were prepared. These raw material powders and the oxide powder as the first or second subcomponent were weighed to have the composition shown in Table 2. The amount of the first and second subcomponents added depends on the amount of the main component [{Ba _1-x Ca _x O} _m
[TiO ₂ + αRe ₂ O ₃ + βMgO + γMnO] 100 parts by weight. An organic solvent such as a polyvinyl butyral-based binder and ethanol was added to the weighed product, and the mixture was wet-mixed with a ball mill to prepare a ceramic slurry. This ceramic slurry is formed into a sheet by a doctor blade method and has a thickness of 4.5.
A rectangular green sheet of μm was obtained. Next, a conductive paste mainly composed of Ni was printed on the ceramic green sheet to form a conductive paste layer for forming internal electrodes.

[0030]

[Table 2]

Thereafter, a plurality of ceramic green sheets on which the conductive paste layer was formed were laminated so that the side from which the conductive paste layer was drawn out was alternated, to obtain a laminate. This laminate was heated to a temperature of 350 ° C. in an N ₂ atmosphere to burn the binder, and then the oxygen partial pressure was 10 ^−9.
It was calcined at a temperature shown in Table 3 for 2 hours in a reducing atmosphere composed of H ₂ —N ₂ —H ₂ O gas of 10 to 10 ⁻¹² MPa to obtain a ceramic sintered body.

After firing, an Ag paste containing a glass frit of B ₂ O ₃ —Li ₂ O—SiO ₂ —BaO system was applied to both end surfaces of the obtained ceramic sintered body, and the paste was heated to 600 ° C. in an N ₂ atmosphere. At this temperature, an external electrode electrically connected to the internal electrode was formed.

The external dimensions of the multilayer ceramic capacitor thus obtained are as follows: width: 5.0 mm, length: 5.7 m
m, thickness: 2.4 mm, and the thickness of the dielectric ceramic layer interposed between the internal electrodes was 3 μm. The total number of effective dielectric ceramic layers was 5, and the area of the counter electrode per layer was 16.3 × 10 ⁻⁶ m ² .

Next, the electrical characteristics of these multilayer ceramic capacitors were measured. Capacitance and dielectric loss (tan δ) were measured using JISC
The measurement was performed according to 5102, and the dielectric constant was calculated from the obtained capacitance. Further, using an insulation resistance meter, a DC voltage of 10 V was applied for 2 minutes to determine the insulation resistance at 25 ° C., and the specific resistance (ρ) was calculated.

Further, the DC bias characteristics were measured. That is,
The capacitance was measured when a DC voltage of 15 V was applied (that is, 5 kV / mm was applied), and the capacitance change rate (ΔC%) with respect to the capacitance when no DC voltage was applied was determined.

Further, the rate of change of the capacitance with respect to the temperature change was measured. The rate of change of the capacitance with temperature is based on the maximum value (ΔC / C20) of the rate of change between −25 ° C. and 85 ° C. based on the capacitance at 20 ° C. and the capacitance at 25 ° C. The maximum value of the rate of change between -55 ° C and 125 ° C (ΔC
/ C25).

Further, as a high temperature load test, a DC voltage of 30 V was applied at a temperature of 150 ° C., and the change with time of the insulation resistance was measured. In the high-temperature load test, the time when the insulation resistance value of each sample became 10 ⁵ Ω or less was defined as the lifetime, and the average lifetime for a plurality of samples was determined.

Further, a DC voltage was applied at a step-up rate of 100 V / sec, and a dielectric breakdown voltage was measured. Table 3 shows the above results.
Shown in

[0039]

[Table 3]

The cross section of the obtained multilayer ceramic capacitor was polished and chemically etched, and the grain diameter of the dielectric ceramic was observed with a scanning electron microscope. Was almost the same as the particle size of barium calcium titanate.

As is clear from Tables 1 to 3, the multilayer ceramic capacitor according to the present invention satisfies the B characteristic standard stipulated by the JIS standard when the rate of change of the capacitance with respect to temperature is in the range of -25 ° C. to + 85 ° C. However, it satisfies the X7R characteristic standard specified in the EIA standard within the range of -55 ° C to 125 ° C. In addition, the rate of change in capacitance when a DC voltage of 5 kV / mm is applied is as small as 51% or less, and the change in capacitance is small even when used in a thin layer. Further, the average life time in the high temperature load test is as long as 52 hours or more, and the firing temperature is 12 hours.
It can be fired at a temperature of 50 ° C. or less.

Here, the reasons for limiting the composition of the present invention will be described. {Ba _1-x Ca _x O} _m TiO ₂ + αRe ₂ O ₃ + βMgO +
γMnO (where Re ₂ O ₃ is Y ₂ O ₃ , Gd ₂ O ₃ , Tb ₂ O ₃ , D
y ₂ O ₃ , Ho ₂ O ₃ , Er ₂ O _3, and Yb ₂ O ₃ , and at least one selected from the group consisting of α, β, and γ, which represents a molar ratio. , CaO amount x
Is 0.005 or less, the rate of change in capacitance due to voltage application is large, and the average life time is extremely short. On the other hand, as shown in Sample No. 2, the CaO amount x was 0.22.
If it exceeds, the dielectric loss is undesirably large. Therefore, the CaO amount x is 0.005 <x ≦ 0.2
A range of 2 is preferred.

As shown in Sample No. 3, the amount α of Re ₂ O ₃ was
If it is less than 0.001, the average life time becomes extremely short, which is not preferable. On the other hand, when the amount α of Re ₂ O ₃ exceeds 0.10 as in Sample No. 4, the temperature characteristic becomes B characteristic / X characteristic.
The 7R characteristics are not satisfied, and the average life time is undesirably short. Therefore, the Re ₂ O ₃ amount α is 0.001 ≦ α ≦
A range of 0.10 is preferred.

When the amount β of MgO is less than 0.001, as in sample No. 5, the rate of change in capacitance due to voltage application is large, and the temperature characteristics do not satisfy the B characteristics / X7R characteristics, which is not preferable. On the other hand, as shown in Sample No. 6, MgO
When the addition amount β exceeds 0.12, the sintering temperature becomes high and the average life time becomes extremely short, which is not preferable.
Therefore, the MgO amount β is preferably in the range of 0.001 ≦ β ≦ 0.12.

When the MnO amount γ is 0.001 or less as in Sample No. 7, the specific resistance is low and the average life time is undesirably short. On the other hand, when the MnO amount γ exceeds 0.12 as in Sample No. 8, the temperature characteristics do not satisfy the B characteristics / X7R characteristics, and the specific resistance decreases.
The average life time is undesirably short. Therefore, M
The nO amount γ is preferably in the range of 0.001 <γ ≦ 0.12.

As shown in sample numbers 9 and 10, (Ba,
When the Ca) / Ti ratio m is 1.000 or less, the temperature characteristics do not satisfy the B characteristics / X7R characteristics, the specific resistance decreases, and short-circuit failure occurs immediately upon application of a voltage in a high-temperature load test. Absent. On the other hand, when the (Ba, Ca) / Ti ratio m exceeds 1.035 as in Sample No. 11, the sinterability is insufficient and the average life time is extremely short, which is not preferable. Therefore, the (Ba, Ca) / Ti ratio m is preferably in the range of 1.000 <m ≦ 1.035.

When the amounts of the first and second subcomponents are 0 as in Sample Nos. 12 and 13, sintering is insufficient,
It is not preferable because the specific resistance is low and short-circuit failure occurs immediately when a voltage is applied in a high-temperature load test. On the other hand, sample number 1
As in 4 and 15, the amount of the first and second subcomponents is 5.0.
If the amount exceeds the weight part, the generation of the secondary phase based on the glass component increases, the temperature characteristics do not satisfy the B characteristic / X7R characteristic, and the average life time is extremely short, which is not preferable. Therefore, the content of either the first or the second subcomponent is preferably in the range of 0.2 to 5.0 parts by weight.

The content of alkali metal oxide contained as an impurity in barium calcium titanate is set to 0.0
The reason for setting the content to 2% by weight or less is that when the content of the alkali metal oxide exceeds 0.02% by weight as in Sample No. 16, the average life time becomes short.

When the average particle size of barium calcium titanate exceeds 0.7 μm as in sample No. 17, the average life time is slightly worse at 52 hours. On the other hand, when the average particle size of barium calcium titanate is less than 0.1 μm as in Sample No. 18, the dielectric constant is slightly smaller at 1040. Therefore, the average particle size of barium calcium titanate is more preferably in the range of 0.1 to 0.7 μm.

Example 2 As a dielectric powder, B in Table 1 was used.
Using barium calcium titanate (Ba _0.90 Ca
_0.10 O) _1.010 • TiO ₂ +0.02 Dy ₂ O ₃ +0.02
A raw material of MgO + 0.010MnO (molar ratio) was prepared. This was heated at 1200 to 1500 ° C. and produced as a first subcomponent having an average particle size of 1 μm or less as shown in Table 4 as L.
i ₂ O- (Si, Ti) was added to O ₂ -MO-based oxide, others were produced multilayer ceramic capacitor in the same manner as in Example 1. The dimensions and shape of the manufactured multilayer ceramic capacitor are the same as those in the first embodiment. And
The electrical characteristics were measured in the same manner as in Example 1. Table 5 shows the results.

[0051]

[Table 4]

[0052]

[Table 5]

As is clear from Tables 4 and 5, A (x = 20, y) in the ternary composition diagram of the Li ₂ O— (Si _w Ti _1-w ) O ₂ —MO-based oxide shown in FIG. = 80, z = 0), B (x =
10, y = 80, z = 10), C (x = 10, y = 7)
0, z = 20), D (x = 35, y = 45, z = 2)
0), E (x = 45, y = 45, z = 10), F (x =
45, y = 55, z = 0) (where x, y, and z are mol%, and w is 0.3 ≦ w <1.
Sample No. 10 to which the oxide was added in or on the region surrounded by the straight line connecting the points indicated by (0 range)
1 to 112, 118 and 120 have a dielectric constant of 185.
0 or more, and the rate of change of capacitance with respect to temperature is -2.
Satisfies the B characteristic standard stipulated in the JIS standard in the range of 5 ° C. to + 85 ° C., and EIA in the range of −55 ° C. and 125 ° C.
Satisfies the X7R characteristic standard specified in the standard. And 5
When the DC voltage of kV / mm is applied, the capacity change rate is 4
Within 3%, the change in capacitance is small even when used in a thin layer. Further, the average life time in the high temperature load test is as long as 80 hours or more, and the firing can be performed at a firing temperature of 1250 ° C. or less.

On the other hand, Li ₂ O— (Si, Ti)
When the O ₂ -MO-based oxide is out of the above composition range, sintering becomes insufficient and a short circuit failure occurs immediately when a voltage is applied in a high-temperature load test as in sample numbers 113 to 117, 119 and 121 to 122. Becomes

(Example 3) As a dielectric powder, B in Table 1 was used.
Using barium calcium titanate (Ba _0.90 Ca
_0.10 O) _1.010 • TiO ₂ + 0.02Gd ₂ O ₃ +0.05
A raw material of MgO + 0.010MnO (molar ratio) was prepared. This was heated at 1200 to 1500 ° C. and prepared as a second subcomponent having an average particle size of 1 μm or less shown in Table 6 as S.
A multilayer ceramic capacitor was manufactured in the same manner as in Example 1 except that an oxide of iO ₂ —TiO ₂ —XO system (including the case where Al ₂ O ₃ and ZrO ₂ were added) was added. The dimensions and shape of the manufactured multilayer ceramic capacitor are the same as those in the first embodiment. Then, the electrical characteristics were measured in the same manner as in Example 1. Table 7 shows the results.

[0056]

[Table 6]

[0057]

[Table 7]

As is clear from Tables 6 and 7, A in the ternary composition diagram of the SiO ₂ —TiO ₂ —XO-based oxide shown in FIG.
(X = 85, y = 1, z = 14), B (x = 35, y =
51, z = 14), C (x = 30, y = 20, z = 5
0), D (x = 39, y = 1, z = 60) (where x,
(y and z are mol%) Samples 201 to 210 to which the oxide is added inside or on the line surrounded by the straight line connecting the points indicated by The change rate of the capacitance with respect to -25 ° C to +85
In the range of ℃, it satisfies the B characteristic standard specified in the JIS standard, and in the range of -55 ° C and 125 ° C, it satisfies the X7R characteristic standard specified in the EIA standard. Moreover, 5 kV / mm
The rate of change in capacitance when the DC voltage is applied is as small as 44% or less, and the change in capacitance is small even when used in a thin layer. Furthermore, the average life time in the high temperature load test is as long as 85 hours or more, and the firing can be performed at a firing temperature of 1250 ° C. or less.

On the other hand, when the SiO ₂ —TiO ₂ —XO-based oxide is out of the above composition range, sample No. 213
As shown in FIGS. 216 and 219, sintering becomes insufficient and short-circuit failure occurs immediately when a voltage is applied in a high-temperature load test.

As shown in sample numbers 211 and 212, S
Al ₂ O ₃ and ZrO are added to the iO ₂ -TiO ₂ -XO-based oxide.
₂ , the specific resistance can be increased. However, as shown in sample numbers 217 and 218, the addition amount of Al ₂ O ₃ exceeds 15 parts by weight, or the addition amount of ZrO ₂ is 5 parts.
If the amount exceeds the weight part, sintering becomes insufficient, and short circuit failure occurs immediately when a voltage is applied in a high temperature load test.

As for the samples within the scope of the present invention obtained in Examples 1 to 3, the particles of the dielectric ceramic were analyzed by a transmission electron microscope. As a result, the Re component (however, Re is Y, Gd, Tb, D
at least one selected from y, Ho, Er and Yb
(Species or more) had a core-shell structure diffused in and near the grain boundaries.

[0062]

As is apparent from the above description, according to the present invention, the dielectric ceramic layer of the multilayer ceramic capacitor is not reduced even if it is fired in a reducing atmosphere, and the dielectric ceramic layer does not become a semiconductor. Since it is constituted, nickel or a nickel alloy, which is a base metal, can be used as an electrode material, and can be fired at a relatively low temperature of 1250 ° C. or less, so that the cost of the multilayer ceramic capacitor can be reduced.

Further, the multilayer ceramic capacitor using the dielectric ceramic composition has a small decrease in the dielectric constant, that is, the capacitance even when a high electric field is applied in a thin layer, and has high reliability. Therefore, it is possible to obtain a small-sized, thin-layer, large-capacity multilayer ceramic capacitor.

[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 internal electrodes 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;

FIG. 4 is a ternary composition diagram of a Li ₂ O— (Si _w Ti _1-w ) O ₂ —MO-based oxide.

FIG. 5 is a ternary composition diagram of an SiO ₂ —TiO ₂ —XO-based oxide.

[Explanation of symbols]

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

 ────────────────────────────────────────────────── ─── Continued on the front page (72) Inventor Yukio Hamachi 2-26-10 Tenjin, Nagaokakyo-shi, Kyoto F-term in Murata Manufacturing Co., Ltd. (reference) 5E082 AB03 BC14 EE04 EE23 EE35 FG06 FG22 FG26 FG27 FG54 GG10 GG11 GG26 GG28 JJ03 JJ05 JJ21 JJ23 MM23 MM24 PP03 PP09 5G303 AA01 AB06 AB11 BA12 CA01 CB01 CB03 CB06 CB16 CB17 CB18 CB30 CB32 CB35 CB38 CB39 CB40 CB41 CB43

Claims (7)

[Claims] 1. A multilayer ceramic capacitor comprising: a plurality of dielectric ceramic layers; an internal electrode formed between the dielectric ceramic layers; and an external electrode electrically connected to the internal electrode. The ceramic layer has the following composition formula: {Ba _{1 -x} Ca _x O} _m TiO ₂ + αRe ₂ O ₃ + βMgO +
γMnO (where Re ₂ O ₃ is Y ₂ O ₃ , Gd ₂ O ₃ , Tb ₂ O ₃ , D
and the _{y 2 O 3, Ho 2 O} 3, Er 2 O 3 and Yb ₂ O ₃ of at least one or more selected from among, alpha, beta and γ represent mole ratio 0.001 ≦ α ≦ 0.10 0.001 ≦ β ≦ 0.12 0.001 <γ ≦ 0.12 1.000 <m ≦ 1.035 0.005 <x ≦ 0.22) and the dielectric relative to 100 parts by weight of the main component content used in the body ceramic layer _{{Ba 1-x Ca x O} } alkali metal oxide of the TiO ₂ in the raw material is 0.02 wt% or less, the first subcomponent Li ₂ O-
An oxide of (Si, Ti) O ₂ —MO (where MO is at least one selected from Al ₂ O ₃ and ZrO ₂ ), and the second subcomponent is SiO ₂ —TiO ₂ — When an XO-based oxide (XO is at least one selected from BaO, CaO, SrO, MgO, ZnO, and MnO) is used, one of the first and second subcomponents may be 0. .2 to 5.0 parts by weight, wherein the internal electrode is made of nickel or a nickel alloy. 2. Ba used in the dielectric ceramic layer
The average particle size of the _1-x Ca _x O｝ TiO ₂ raw material is 0.1 to 0.
The multilayer ceramic capacitor according to claim 1, wherein the thickness is 7 µm. 3. The method according to claim 1, wherein the first subcomponent is xLi ₂ O-y.
When represented by (Si _w Ti _1-w ) O ₂ -zMO (where x, y and z are mol%, and w is in the range of 0.30 ≦ w ≦ 1.0), A (x = 20, y = 80, z = 0) B (x = 10, y = 80, z = 10) C (x = 10, y = 70, z = 20) D (x = 35, y = 45, z = 20) E (x = 45, y = 45, z = 10) F (x = 45, y = 55, z = 0) (However, the straight line A− For the composition on F, w is 0.3 ≦ w
3. The multilayer ceramic capacitor according to claim 1, wherein the multilayer ceramic capacitor is located inside or on a line surrounded by a straight line connecting the points indicated by (<1.0 range). 4. 4. The method according to claim 1, wherein the second subcomponent is xSiO ₂ -yT
When represented by iO ₂ -zXO (where x, y and z are mol%), A (x = 85, y = 1, z = 14) of a ternary composition diagram having each component at the top (X = 35, y = 51, z = 14) C (x = 30, y = 20, z = 50) D (x = 39, y = 1, z = 60) A straight line connecting points 3. The multilayer ceramic capacitor according to claim 1, wherein the multilayer ceramic capacitor is located inside or on a line of the enclosed area. 5. The method according to claim 1, wherein the second sub-component comprises the SiO ₂
The oxide 100 parts by weight of -TiO ₂ -XO series, A
at least one of l ₂ O ₃ and ZrO _{2 in} a total of 15
The following parts by weight (however, less ZrO ₂ is 5 parts by weight), characterized in that it contains, multilayer ceramic capacitor according to claim 4, wherein. 6. The laminate according to claim 1, wherein the external electrode is formed of a sintered layer of a conductive metal powder or a conductive metal powder to which glass frit is added. Ceramic capacitors. 7. The external electrode, comprising: a sintered layer of a conductive metal powder or a conductive metal powder to which glass frit is added;
The multilayer ceramic capacitor according to any one of claims 1 to 5, comprising a plating layer formed thereon.