JP3493882B2 - Multilayer ceramic capacitors - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a monolithic ceramic capacitor used in electronic equipment, and more particularly to a monolithic ceramic capacitor having internal electrodes made of nickel or nickel alloy.

[0002]

2. Description of the Related Art Conventionally, the manufacturing process of a laminated ceramic capacitor is generally as follows. First,
A sheet-shaped dielectric material whose surface is coated with an electrode material serving as an internal electrode is prepared. As the dielectric material, for example, a material containing BaTiO ₃ as a main component is used. Next, a sheet-shaped dielectric material coated with this electrode material is laminated, thermocompression-bonded, and integrated to be fired at 1250 to 1350 ° C. in a natural atmosphere to obtain a dielectric ceramic having internal electrodes. can get. Then, an external electrode that is electrically connected to the internal electrode is printed on the end surface of the dielectric ceramic, so that a laminated ceramic capacitor is obtained.

Therefore, the material for the internal electrodes must satisfy the following conditions. (A) Since the dielectric ceramic and the internal electrode are fired at the same time, the dielectric ceramic must have a melting point equal to or higher than the firing temperature.

(B) It should not be oxidized even in an oxidizing high temperature atmosphere and should not react with the dielectric.

Noble metals such as platinum, gold, palladium or silver-palladium alloys have been used as electrodes satisfying such conditions.

However, while these electrode materials have excellent characteristics, they are expensive. Therefore, the ratio of the electrode material cost to the monolithic ceramic capacitor is 30 to 7
It reached 0%, which was the biggest factor in raising the manufacturing cost.

N having a high melting point other than noble metal
Although there are base metals such as i, Fe, Co, W, and Mo, these base metals are easily oxidized in a high-temperature oxidizing atmosphere and cannot serve as an electrode.
Therefore, in order to use these base metals as the internal electrodes of the monolithic ceramic capacitor, it is necessary to fire them together with the dielectric ceramic in a neutral or reducing atmosphere. However, the conventional dielectric ceramic material has a drawback in that it is significantly reduced when it is fired in such a neutral or reducing atmosphere and becomes a semiconductor.

In order to overcome such drawbacks, for example, as disclosed in Japanese Patent Publication No. 57-42588, a barium titanate solid solution having a barium site / titanium site ratio in excess of the stoichiometric ratio is used as a dielectric. A body material and a dielectric material obtained by adding a rare earth oxide such as La, Nd, Sm, Dy or Y to a barium titanate solid solution as in JP-A-61-101459 have been considered.

Further, as the one in which the change in the dielectric constant with temperature is made small, for example, the composition of BaTiO ₃ --CaZrO ₃ --MnO--MgO system disclosed in JP-A-62-256422 and BaTiO _{3 in} JP-B-61-14611 are disclosed. -(M
g, Zn, Sr, Ca) O—B ₂ O ₃ —SiO ₂ based dielectric materials have been proposed. By using such a dielectric material, it is possible to obtain a dielectric ceramic that does not become a semiconductor even when fired in a reducing atmosphere, and it is possible to manufacture a monolithic ceramic capacitor using a base metal such as nickel as an internal electrode. became.

[0010]

With the development of electronics in recent years, miniaturization of electronic parts has progressed rapidly, and the tendency toward miniaturization and large capacity of multilayer ceramic capacitors has become remarkable. Therefore, the dielectric constant of the dielectric material and the thinning of the dielectric layer are rapidly increasing. Therefore, there is an increasing demand for a dielectric material having a high dielectric constant, a small change in the dielectric constant with temperature, and excellent reliability.

However, the dielectric materials disclosed in JP-B-57-42588 and JP-A-61-101459 have a large dielectric constant, but the crystal grains of the obtained dielectric porcelain are large. When the thickness of the dielectric layer in the monolithic ceramic capacitor is 10 μm or less, the number of crystal grains present in one layer is reduced, and the reliability is lowered. Further, there is a problem that the change in the dielectric constant with temperature is large, and it has not been possible to meet the market demand.

On the other hand, in the dielectric material disclosed in Japanese Patent Laid-Open No. 62-256422, CaZrO has a relatively high dielectric constant and the obtained dielectric ceramic has small crystal grains and a small change in dielectric constant with temperature. ₃ and CaT produced in the firing process
Since iO ₃ easily forms a secondary phase together with Mn and the like, there is a problem in reliability.

Further, in the dielectric material disclosed in Japanese Patent Publication No. 61-14611, the obtained dielectric constant is 2000-
It is 2,800, which is disadvantageous in that the multilayer ceramic capacitor is small and has a large capacity. Furthermore, the temperature range specified by the EIA standard is -55.
There is a problem in that the rate of change in capacitance cannot be satisfied within ± 15% between ℃ and +125 ℃.

The non-reducing dielectric porcelain compositions proposed so far, including the above-mentioned compositions, have a lower insulation resistance than the conventional materials, and are particularly remarkable under high electric field strength. Therefore, this has been a major obstacle in reducing the thickness of the dielectric. In order to cover this low insulation resistance, a means of lowering the rated voltage has been generally used when the layer is thin.

By the way, in a small-sized and large-capacity monolithic ceramic capacitor, in order to support automatic surface mounting, a plating film such as solder is formed as an external electrode on a baked electrode of conductive metal powder.

Electroplating is generally used as a method for forming a plating film. Normally, fine voids are formed in the baked electrode of conductive metal powder. Therefore, when the monolithic ceramic capacitor is dipped in a plating solution to form a plating film thereon, the plating solution may enter the voids of the baking electrode and reach the interface between the internal electrode and the dielectric ceramic. Therefore, when the above-mentioned dielectric material is used, there is a problem that the reliability is lowered.

Therefore, the main object of the present invention is to calculate the product of the dielectric constant of 3000 or more and the insulation resistance and the capacitance (CR
Product) is 5000 MΩ · μF or more, the decrease rate of the insulation resistance under high electric field strength is low, the reliability is excellent even when the dielectric thickness is thin, the rated voltage is high, and the temperature of the capacitance is high. The characteristics satisfy the B characteristics specified by the JIS standard and the X7R characteristics specified by the EIA standard,
An object of the present invention is to provide a low-cost, small-sized, large-capacity monolithic ceramic capacitor that is highly reliable regardless of plating.

[0018]

The present invention has been made in view of the above objects. The monolithic ceramic capacitor of the present invention includes a plurality of dielectric ceramic layers, a plurality of internal electrodes formed between the dielectric ceramic layers such that respective edges are exposed at both end surfaces of the dielectric ceramic layer, and exposed. In the monolithic ceramic capacitor including an external electrode provided so as to be electrically connected to the internal electrode, the dielectric ceramic layer has an alkali metal oxide content of 0.03% by weight as an impurity. It consists of the following barium titanate, yttrium oxide, zinc oxide, and nickel oxide, and has the following composition formula: (1-α-β) {BaO} _m · TiO ₂ + αY ₂ O ₃ + β
(Zn _1-X Ni _x ) O (where α, β, m, and x are 0.0025 ≦ α ≦ 0.03 0.0025 ≦ β ≦ 0.08 β / α ≦ 80 <x <11 1 .000 ≦ m ≦ 1.035) with respect to 100 mol of the main component represented by
0.2 to 2.5 mol in terms of magnesium oxide MgO, 0.05 to 2.0 mol of MnO, and AZrO ₃
Up to 4.0 mol (however, A is Ba, Sr and Ca
At least one) containing added further 100 parts by weight of the components, as 100 parts by weight of the _{components, Li 2 O-M 1 O} -M 2 O- (Ti, Si) O 2 ( only one of
However , M ₁ is at least _one of Zn and Mn, and M ₂ is B.
a, Sr, Ca and / or Mg) and a table
When Li ₂ O: 2-45 mol%, M ₁ O: 0-4
0 mol%, M ₂ O: 5 to 40 mol%, (Ti, Si)
O _2: 35 to 70 mol%, (provided that, (Ti, Si) O ₂
Of which the SiO ₂ component is 15 mol% or more)
That it is constituted by an oxide glass 0.2 to 3.0 parts by weight containing material, wherein the inner electrode is characterized to be constituted by nickel or a nickel alloy.

[0019]

In the monolithic ceramic capacitor of the present invention, the oxide glass is 100 parts by weight,
At least one of the following components is preferably added and contained.

(1) 20 parts by weight or less of Al ₂ O ₃ (2) 10 parts by weight or less of ZrO _{2 Further} , in the laminated ceramic capacitor of the present invention,
It is preferable that the external electrode is formed of a sintered layer of conductive metal powder or conductive metal powder added with glass frit. In addition, it is preferable that the external electrode includes a first layer formed of a sintered layer of a conductive metal powder or a conductive metal powder to which glass frit is added, and a second layer formed of a plated layer thereon.

[0022]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below. The monolithic ceramic capacitor of the present invention includes barium titanate, as a material of the dielectric ceramic layer,
By adjusting the composition ratio of yttrium oxide, zinc oxide, and nickel oxide as described above, magnesium oxide, manganese oxide, and AZrO ₃ (where A is at least one of Ba, Sr, and Ca) within the above range. The content of the oxide glass containing Li ₂ O—MO— (Ti, Si) O ₂ (wherein R is at least one of Ba, Sr, Ca and Mg) as a main component in the above range. By using the dielectric porcelain composition added and contained therein, the insulation resistance is 5000 MΩ · μF or more when expressed by the product (CR product) with the capacitance even when fired in a reducing atmosphere. In addition, the rate of decrease of the value is low even under high electric field strength, and the reliability is excellent even if the thickness of the dielectric is reduced.
It is possible to obtain a dielectric ceramic exhibiting a high dielectric constant of 000 or more and having a capacitance change rate satisfying the X7R characteristic defined by EIA.

In the present invention, the barium titanate is present as an impurity in the main component of the dielectric ceramic composition constituting the dielectric ceramic layer of barium titanate, yttrium oxide, zinc oxide and nickel oxide. Alkaline earth metal oxides such as SrO and CaO, Na
Alkali metal oxides such as ₂ O and K ₂ O, other Al ₂ O ₃ ,
It has been confirmed that the content of alkali metal oxides such as Na ₂ O and K ₂ O among oxides such as SiO ₂ has a great influence on electrical characteristics. That is, the amount of alkaline earth metal oxide present as an impurity in barium titanate is 0.
It has been confirmed that when the content exceeds 03% by weight, the obtained dielectric constant becomes smaller than 3,000.

Further, Li ₂ O is contained in the dielectric ceramic layer.
-MO- (Ti, Si) O ₂ (where M is Ba, S
It has been confirmed that the addition of oxide glass containing at least one of r, Ca, Mg, Zn, and Mn as a main component improves the sinterability and the plating resistance.

In the multilayer ceramic capacitor of the present invention, oxide glass is used as Li ₂ O-M ₁ O-M ₂ O.
-(Ti, Si) O ₂ (where M ₁ is at least _one of Zn and Mn and M ₂ is at least one of Ba, Sr, Ca, and Mg) is within the above composition range. near Ru. It should be noted that M ₁ O has the same characteristics as those of M ₁ O even if it is not added.

In the monolithic ceramic capacitor of the present invention, the oxide glass is 100 parts by weight,
20 parts by weight or less of the following (1) Al ₂ O ₃ and (2) ZrO ₂
It is preferable that at least one of 10 parts by weight or less is added and contained. This makes it possible to obtain a higher insulation resistance.

Further, in the monolithic ceramic capacitor of the present invention, it is preferable that the external electrode is composed of a sintered layer of conductive metal powder or conductive metal powder to which glass frit is added.

Further, in the laminated ceramic capacitor of the present invention, the external electrode is composed of a first layer formed of a sintered layer of conductive metal powder or conductive metal powder to which glass frit is added, and a plated layer thereover. It is preferably composed of a second layer.

Next, the present invention will be described more specifically based on examples, but the present invention is not limited to such examples.

[0030]

EXAMPLES An example of the present invention will be described below.
FIG. 1 is a sectional view of this embodiment. The monolithic ceramic capacitor 10 includes a monolithic ceramic dielectric 12. The multilayer ceramic dielectric 12 includes a plurality of first dielectric ceramic layers 14a and two second dielectric ceramic layers 1a.
It is formed by laminating 4b. In this laminated dielectric ceramic body 12, the second dielectric ceramic layer 1
4b is arranged on both end surfaces, and the two second dielectric ceramic layers 14b are the plurality of first dielectric ceramic layers 14a.
So that the dielectric ceramic layers 14a and 14b are sandwiched between them.
These dielectric ceramic layers 14a, 14
b is laminated with the internal electrode 16 interposed. Further, the external electrodes 18,
The first plating film 20a and the second plating film 20b are formed in this order. Nickel, copper, or the like is used as the first plating film 20a, and the second plating film 2
As 0b, solder, tin, or the like is used. That is,
The monolithic ceramic capacitor 10 is formed to have a rectangular parallelepiped chip type.

Next, a method of manufacturing the monolithic ceramic capacitor 10 according to the present invention will be described in the order of manufacturing steps.
First, the laminated dielectric ceramic 12 is formed as follows. As shown in FIG. 2, barium titanate, yttrium oxide, zinc oxide, nickel oxide, magnesium oxide, manganese oxide, AZrO ₃ (where A is Ba,
At least one of Sr and Ca) and Li ₂ O-
MO- (Ti, Si) O ₂ (where M is Ba, S
A first dielectric ceramic layer 14a (green sheet) is prepared in the form of a sheet by slurrying a material powder made of an oxide glass containing at least one of r, Ca, Mg, Zn and Mn as a main component. An internal electrode 16 made of nickel or nickel alloy is formed on one surface of the internal electrode 16. The internal electrode 16 may be formed by screen printing, vapor deposition, or plating. A required number of the first dielectric ceramic layers 14a on which the internal electrodes 16 are formed are laminated, and sandwiched by the second dielectric ceramic layers 14b on which the internal electrodes 16 are not formed, as shown in FIG. And afterwards,
The laminated body is fired at a predetermined temperature in a reducing atmosphere to form the laminated dielectric ceramic body 12.

Next, two external electrodes 18 are formed on both end faces of the laminated dielectric ceramic body 12 so as to be connected to the internal electrodes 16. As a material of the external electrode 18,
The same material as the internal electrode 16 can be used. Further, as the material of the external electrode 18, silver, palladium, silver-palladium alloy, or the like can be used, but an appropriate material is selected in consideration of the intended use of the monolithic ceramic capacitor 10, the place of use, and the like. . In addition, the external electrode 18
Is formed by applying a metal powder paste as a material to the laminated dielectric ceramic body 12 obtained by firing and baking it. It is applied before firing and formed simultaneously with the laminated dielectric ceramic body 12. May be. After that, the outer electrode 18 is plated with nickel, copper, etc.
Plating film 20a is formed. Finally, the plating film 20 such as solder or tin is formed on the first plating film 20a.
b is formed, and a chip type multilayer ceramic capacitor 1
0 is produced.

Example 1 First, TiCl ₄ and Ba (NO ₃ ) ₂ having various purities as starting materials were prepared and weighed, and then titanyl barium oxalate (BaTiO ₃ ) was added with oxalic acid.
The precipitate was obtained as (C ₂ O ₄ ) .4H ₂ O). This precipitate was decomposed by heating at a temperature of 1000 ° C. or higher, and four types of barium titanate (BaTiO 3) shown in Table 1 were used.
₃ ) was synthesized. In addition, 24Li ₂ O-6MnO-14Ba
Oxide, carbonate and hydroxide of each component were weighed so that the composition ratio was O-6CaO-3TiO ₂ -47SiO ₂ (mol%), mixed and pulverized, and then evaporated and dried to obtain a powder. . This powder is placed in an alumina crucible at 1300 ° C.
After holding for 1 hour, it was rapidly cooled and pulverized to obtain an oxide glass having an average particle diameter of 1 μm or less.

[0034]

[Table 1]

Next, BaCO ₃ for adjusting the Ba / Ti molar ratio m of barium titanate and Y ₂ O ₃ , ZnO, NiO, MgO, MnO and BaZrO having a purity of 99% or more.
₃ , SrZrO ₃ , and CaZrO ₃ were prepared. These raw material powders and oxide glass were blended so as to have a composition ratio shown in Table 2 to obtain a blend. A polyvinyl butyral binder and an organic solvent such as ethanol were added to this mixture and wet mixed by a ball mill to prepare a ceramic slurry. This ceramic slurry was formed into a sheet by a doctor blade method to obtain a rectangular green sheet having a thickness of 14 μm. Next, a conductive paste mainly containing Ni is printed on the ceramic green sheet,
A conductive paste layer for forming internal electrodes was formed.

[0036]

[Table 2]

A plurality of ceramic green sheets having a conductive paste layer formed thereon were laminated so that the sides from which the conductive paste was drawn out were staggered to obtain a laminate. This laminated body is heated to a temperature of 350 ° C. in an N ₂ atmosphere,
After burning the binder, oxygen partial pressure 10 ^-9 to 10 ^-12 M
The ceramic sintered body was obtained by firing 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 Pa. Silver paste was applied to both end faces of this ceramic sintered body and baked at a temperature of 600 ° C. in an N ₂ atmosphere to form external electrodes electrically connected to the internal electrodes.

[0038]

[Table 3]

The external dimensions of the monolithic ceramic capacitor thus obtained are: width: 1.6 mm, length: 3.2
mm, thickness: 1.2 mm, and the thickness of the dielectric ceramic layer interposed between the internal electrodes was 10 μm. The total number of effective dielectric ceramic layers was 19, and the area of the counter electrode per layer was 2.1 mm ² .

Capacitance (C) and dielectric loss (tan δ)
Using an automatic bridge type measuring instrument, frequency 1 KHz,
Measurement was performed at 1 Vrms and a temperature of 25 ° C., and the dielectric constant (ε) was calculated from the capacitance. Next, in order to measure the insulation resistance (R), a DC voltage of 16 V and 100 V was applied for 2 minutes at a temperature of 25 ° C. using an insulation resistance meter to measure the insulation resistance (R), and the capacitance ( The product of C) and the insulation resistance (R), that is, the CR product was obtained. In addition, the rate of change of capacitance with respect to temperature change was measured.

Regarding the rate of change of capacitance with respect to temperature change, the capacitance at 20 ° C. is used as a reference of -25 ° C.
And the rate of change at 85 ° C (ΔC / C ₂₀ ° C), and the rate of change at −55 ° C and 125 ° C (ΔC / C ₂₀ ° C) based on the capacitance at 25 ° C (Δ
C / C ₂₅ ° C) and a value whose change rate is maximum as an absolute value within the range of -55 ° C to 125 ° C (| ΔC | max)
showed that.

Further, as a high temperature load life test, a DC voltage of 150 V was applied at a temperature of 150 ° C. to each of 36 samples, and the change in insulation resistance over time was measured. In the high temperature load life test, the insulation resistance (R) of each sample was 10 ⁶ Ω.
The life time is defined as the time when it becomes the following, and the average life time is shown. The above results are shown in Table 3.

As is clear from Table 1, Table 2 and Table 3, the multilayer ceramic capacitor of the present invention has a dielectric constant ε of 3,000.
The above is high, the dielectric loss tangent tan δ is 2.5% or less, and the rate of change of the capacitance with respect to temperature satisfies the B characteristic standard stipulated in JIS in the range of −25 ° C. to 85 ° C.
X7R specified in EIA standard within the range of ℃ and 125 ℃
Satisfies the characteristic standards.

Moreover, the insulation resistance measured at 16 V and 100 V is 5,000 when expressed by CR product.
It shows high values such as MΩ · μF and 2,000 MΩ · μF or more. Moreover, the average life time is as long as 300 hours or more. Further, it is possible to sinter at a relatively low firing temperature of 1300 ° C. or lower.

Here, the reason for limiting the composition of this embodiment will be described. (1-α-β) {BaO} _m · TiO ₂ + αY
_{In 2} O ₃ + β (Zn _1-X Ni _X ) O, α is 0.002
The range of 5 ≦ α ≦ 0.03 is limited to that when the amount α of Y ₂ O ₃ is less than 0.0025 as in Sample No. 1, the dielectric constant ε is as low as 3,000 or less, and , Dissipation factor tan
This is because δ exceeds 2.5%, the rate of change in capacitance with temperature increases, and the average life time becomes extremely short. On the other hand, as in Sample No. 18, the Y ₂ O ₃ amount α is 0.03.
If it exceeds, the dielectric constant does not exceed 3,000, the insulation resistance is lowered, and the average life time is shortened.

Further, β was limited to the range of 0.0025 ≦ β ≦ 0.08 as in Sample No. 2 (Zn, N
i) When the O amount β is less than 0.0025, the dielectric loss tangent t
anδ exceeds 2.5%, insulation resistance is low, average life time is short, the rate of change in capacitance is large, and JIS standard B characteristics and EIA standard X7R
This is because the characteristics will not be satisfied. On the other hand, sample number 19
When the (Zn, Ni) O amount β exceeds 0.08, the insulation resistance at 100V is 2000 MΩ · μF.
This is because the average life time becomes shorter than 300 hours without exceeding.

Further, x is limited to the range of 0 <x <1 as shown in Sample No. 3 because N in (Zn, Ni) O is
This is because when the value of the i amount x is 0, the sintering temperature exceeds 1300 ° C. and the dielectric constant becomes smaller than 3000. On the other hand, in the case where the value of the Ni content x is 1 as in the case of Sample No. 9, the insulation resistance at the time of applying 100V exceeds 2000 MΩ · μF when the (Zn, Ni) O content β is more than 0.06. This is because the average life time becomes shorter than 300 hours, which is not preferable.

The range of β / α ≦ 8 is limited to
As in Sample No. 20, Y ₂ O ₃ content α and (Zn, Ni) O
This is because when the ratio β / α of the amount β is larger than 8, the temperature change rate of the capacitance becomes large. Note that β / α may be 8 or less, and more preferably 1/4 ≦ β /
The range is α ≦ 4.

Further, m is limited to the range of 1.000≤m≤1.035 because the reducing property is reduced when the molar ratio m of barium titanate is less than 1.000, as in Sample No. 4. This is because when fired in an atmosphere, the porcelain is reduced, becoming a semiconductor, and the insulation resistance decreases. On the other hand, sample number 2
When the molar ratio m exceeds 1.035 as in No. 1, the sinterability is extremely deteriorated.

Further, magnesium oxide is limited to the range of 0.2 to 2.5 mol in terms of MgO, when the amount of MgO is less than 0.2 mol, as in Sample No. 5,
The insulation resistance when applying 00V does not exceed 2000 MΩ · μF, and the average life time is shorter than 300 hours.
This is because the temperature change rate of the electrostatic capacitance satisfies the X7R characteristic standard defined by the EIA standard, but cannot satisfy the B characteristic standard defined by the JIS standard. On the other hand, when the amount of MgO exceeds 2.5 mol as in Sample No. 22, the sintering temperature increases, the dielectric constant does not exceed 3,000, and the insulation resistance decreases.

Further, the MnO content is limited to the range of 0.05 to 2.0 mol. The reason for limiting the MnO content is that if the MnO content is less than 0.05 mol, as shown in sample No. 6, the insulation resistance decreases and the average This is because the life time is shortened. On the other hand, when the amount of MnO exceeds 2.0 mol as in Sample No. 23, 100
This is because the insulation resistance when V is applied is reduced and the average life time is shortened.

Further, AZrO ₃ was limited to a range of 4.0 mol or less as shown in Sample No. 8 in which AZrO ₃ (A is at least one of Ba, Sr and Ca) is not contained. In some cases, the insulation resistance will decrease, which is
This is because it is particularly noticeable when 100 V is applied, and the average life time is shortened. On the other hand, as in sample number 25, A
When ZrO ₃ exceeds 4.0 mol, the dielectric constant becomes low, and the temperature change rate of capacitance satisfies the X7R characteristic standard defined by the EIA standard, but JIS
This is because the B characteristic standard defined by the standard cannot be satisfied.

Further, the oxide glass is limited to the range of 0.2 to 3.0 parts by weight when the amount of oxide glass is less than 0.2 parts by weight, as in Sample No. 7. This is because as the sintering temperature increases, the insulation resistance decreases and the average life time becomes extremely short. On the other hand, when the amount of the oxide glass exceeds 3.0 parts by weight as in Sample No. 24, the dielectric constant decreases and the temperature change rate of the capacitance increases.

The amount of the alkali metal contained in barium titanate as an impurity was limited to 0.03% by weight or less because the amount of the alkali metal contained in barium titanate as an impurity was as shown in Sample No. 26. 0.03% by weight
This is because if it is larger than this, the dielectric constant is lowered.

(Example 2) As a dielectric powder, A in Table 1 was used.
Barium titanate of 0.979 {BaO}
_1.010・ TiO ₂ + 0.007Y ₂ O ₃ + 0.007ZnO
Prepare 100% of the main component consisting of + 0.007NiO (molar ratio), a raw material blended such that MgO is 1.2 mol, MnO is 0.35 mol, and BaZrO ₃ is 1.2 mol, Table 4 prepared in the same manner as in Example 1
The oxide glass having an average particle size of 1 μm or less shown in is added,
In the same manner as in Example 1, a laminated ceramic capacitor having an external electrode made of silver electrically connected to the internal electrode was formed. The outer dimensions of the manufactured monolithic ceramic capacitor are the same as those in the first embodiment.

[0056]

[Table 4]

Then, the electrical characteristics of these were measured. Capacitance (C) and dielectric loss (tan δ) were measured at a frequency of 1 KHz, 1 Vrm using an automatic bridge type measuring instrument.
s, measured at a temperature of 25 ° C, from the capacitance to the dielectric constant (ε)
Was calculated. Next, in order to measure the insulation resistance (R),
Using an insulation resistance tester, apply DC voltage of 16V and 100V to 2
The voltage was applied for minutes, and the insulation resistance (R) at 25 ° C. was measured to obtain the product of the electrostatic capacitance (C) and the insulation resistance (R), that is, the CR product. In addition, the rate of change of capacitance with respect to temperature change was measured.

Regarding the rate of change of the capacitance with respect to the temperature change, the capacitance at 20 ° C. was used as a reference at -25 ° C.
And the rate of change at 85 ° C (ΔC / C ₂₀ ° C), and the rate of change at −55 ° C and 125 ° C (ΔC / C ₂₀ ° C) based on the capacitance at 25 ° C (Δ
C / C ₂₅ ° C.) and a value whose change rate is maximum as an absolute value within the range of −55 ° C. to 125 ° C. (| ΔC / C ₂₀ ° C. |
max) was shown.

After these measurements, a nickel plating solution containing nickel sulfate, nickel chloride and boric acid was prepared,
The silver external electrode was nickel-plated by the barrel plating method. Finally, a solder plating solution consisting of AS bath (alkanol sulfonic acid) is prepared, and the nickel plating film is solder-plated by the barrel plating method to obtain a laminated ceramic capacitor plated on the external electrodes. It was

The capacitance (C) of the obtained monolithic ceramic capacitor was measured at a frequency of 1 KHz, 1 Vrms and a temperature of 25 ° C. using an automatic bridge type measuring device.
Next, in order to measure the insulation resistance (R), a DC voltage of 16 V and 100 V was applied for 2 minutes using an insulation resistance meter to measure the insulation resistance (R) at 25 ° C. The product of (C) and insulation resistance (R), that is, the CR product was obtained. The above results are shown in Table 5.

[0061]

[Table 5]

As is clear from Tables 4 and 5, the monolithic ceramic capacitor composed of the dielectric ceramic layer containing the oxide glass of the present embodiment has a dielectric constant ε of 3.
2,000 or more, the dielectric loss tangent tan δ is 2.5% or less, and the rate of change in capacitance with temperature is -25 ° C to 85 ° C.
B characteristic standard stipulated in JIS standard in the range of ℃, -5
X7 specified in the EIA standard within the range of 5 ° C and 125 ° C
Satisfies the R characteristic standard. Moreover, even if plated
The electrical characteristics do not deteriorate.

Here, the reasons for limiting the composition of the oxide glass used in this example will be described. Sample number 1
As in No. 01, when the oxide glass of this example is not added and contained, the sintering temperature becomes high, the insulation resistance becomes low, and the insulation resistance further decreases due to the plating.

Li ₂ O-M ₁ O-M ₂ O- (Ti, Si)
In an oxide glass made of O ₂ (however, M ₁ is at least one of Zn and Mn, and M ₂ is at least one of Ba, Sr, Ca, and Mg), Li ₂ O
Is limited to the range of 2 to 45 mol% by the sample number 10
2, when the amount of Li ₂ O is less than 2 mol%, the sintering temperature becomes higher than 1300 ° C. and the dielectric loss tangent tan δ.
Over 2.5%, the rate of change in capacitance with temperature increases. On the other hand, when the amount of Li ₂ O exceeds 40 mol% as in sample No. 116, delamination occurs.

Further, the M ₁ O content was limited to the range of 0 to 40 mol% because the M ₁ O content was 40% as in Sample No. 115.
This is because when it exceeds mol%, the sintering temperature becomes high and the dielectric constant does not exceed 3,000.

[0066] Further, The reason for limiting the M ₂ O in the range of 5 to 40 mol%, as in Sample No. 103, if M ₂ O amount is less than 5 mol%, the sintering temperature is from 1300 ° C. And the dielectric loss tangent taδ exceeds 2.5, and 100V
This is because the insulation resistance during application becomes lower than 2000 MΩ · μF. On the other hand, when the amount of M ₂ O exceeds 40 mol% as in Sample No. 117, the sintering temperature increases and the dielectric constant does not exceed 3,000. Furthermore, the rate of change in capacitance with temperature increases, and the insulation resistance slightly decreases due to plating.

Further, (Ti, Si) O ₂ is limited to the range of 35 to 70 mol% when the amount of (Ti, Si) O ₂ is less than 35 mol% as in Sample No. 104. This is because the sintering temperature becomes high and the insulation resistance becomes extremely low due to plating. On the other hand, like sample number 118 (T
This is because if the amount of i, Si) O ₂ exceeds 70 mol%, the sintering temperature becomes high and the load life time at high temperature becomes short.

Furthermore, among (Ti, Si) O ₂ , Si
O ₂ was limited to the range of 15 mol% or more because when the amount of SiO ₂ is less than 15 mol% as in sample No. 105, the sintering temperature becomes high and the insulation resistance is extremely lowered by plating. This is because it will end up. Sample number 106
As described above, when the amount of TiO ₂ is 0, the insulation resistance is extremely reduced by plating, which is not preferable.

Here, Li ₂ O-M ₁ O-M ₂ O- (T
i, Si) O ₂ oxide glass with Al ₂ O ₃ or ZrO ₂
In addition, the addition of 16V and 10
Insulation resistance when 0V is applied is 6000MΩ ・ μF,
This is because a monolithic ceramic capacitor of 3000 MΩ · μF can be obtained.

The reasons for limiting the composition of Al ₂ O ₃ and ZrO ₂ will be described. Al ₂ O ₃ was limited to the range of 20 parts by weight or less because the amount of Al ₂ O ₃ was 2 as shown in Sample No. 119.
This is because if the amount exceeds 0 part by weight, the sinterability is lowered, the dielectric constant does not exceed 3,000, and the insulation resistance is lowered.
In addition, the insulation resistance is also extremely reduced by the plating.

Further, the ZrO ₂ content is limited to the range of 10 parts by weight or less. When the amount of ZrO ₂ exceeds 10 parts by weight as in Sample No. 120, the sinterability is lowered and the dielectric constant is 3%. This is because the insulation resistance decreases without exceeding 1,000. In addition, the insulation resistance is also extremely reduced by the plating.

In the above examples, the powder prepared by the oxalic acid method was used as the barium titanate, but the barium titanate powder prepared by the alkoxide method or the hydrothermal synthesis method is not limited to this. They may be used, and by using these powders, the characteristics shown in this example may be improved. Further, yttrium oxide, cobalt oxide, nickel oxide, and the like also used oxide powders, but the invention is not limited to this, and alkoxides can be used if blended so as to form the dielectric ceramic layer within the scope of the present invention. The use of a solution of organic metal or the like does not impair the obtained characteristics.

[0073]

When the monolithic ceramic capacitor of the present invention is used, the dielectric ceramic layer of the monolithic ceramic capacitor is composed of a dielectric ceramic composition that is not reduced even when fired in a reducing atmosphere and does not become a semiconductor. Therefore, nickel and nickel, which are base metals, can be used as the electrode material and can be fired at a relatively low temperature of 1300 ° C. or lower, so that the cost of the monolithic ceramic capacitor can be reduced.

In addition, the monolithic ceramic capacitor using this dielectric ceramic composition has a dielectric constant of 3,000 or more, and has a high dielectric constant as described above.
Dielectric constant changes little with temperature, insulation resistance is high, insulation resistance drop rate is also high under high electric field strength, reliability is excellent even when the dielectric thickness is thin, and high rated voltage is small and large capacity It is possible to obtain the monolithic ceramic capacitor of.

Further, since there is no deterioration in electrical characteristics due to plating, it is possible to cope with automatic surface mounting.

[Brief description of drawings]

FIG. 1 is a sectional view showing an embodiment of the present invention.

FIG. 2 is a plan view showing an example of a first dielectric ceramic layer of the present invention.

FIG. 3 is an exploded perspective view showing a state in which a laminated dielectric ceramic body is formed by laminating a first dielectric ceramic layer and a second dielectric ceramic layer.

[Explanation of symbols]

10 Multilayer ceramic capacitors 12 Multilayer dielectric ceramic body 14a First dielectric ceramic layer 14b Second dielectric ceramic layer 16 internal electrodes 18 External electrode 20a First plating film 20b Second plating film

─────────────────────────────────────────────────── ─── Continuation of the front page (56) Reference JP-A-6-251985 (JP, A) JP-A-5-144319 (JP, A) JP-A-8-59344 (JP, A) (58) Field (Int.Cl. ⁷ , DB name) H01G 4/12

Claims (4)

(57) [Claims] 1. A plurality of dielectric ceramic layers, a plurality of internal electrodes formed between the dielectric ceramic layers such that respective edges are exposed at both end faces of the dielectric ceramic layer, and the exposed internal portions. A multilayer ceramic capacitor including an external electrode provided so as to be electrically connected to an electrode, wherein the dielectric ceramic layer is made of titanium in which an alkali metal oxide content as an impurity is 0.03% by weight or less. And barium acid, yttrium oxide, zinc oxide, and nickel oxide, and has the following composition formula: (1-α-β) {BaO} _m · TiO ₂ + αY ₂ O ₃ + β
(Zn _1-X Ni _x ) O (where α, β, m, and x are 0.0025 ≦ α ≦ 0.03 0.0025 ≦ β ≦ 0.08 β / α ≦ 80 <x <11 1 .000 ≦ m ≦ 1.035) with respect to 100 mol of the main component represented by
0.2 to 2.5 mol in terms of magnesium oxide MgO, 0.05 to 2.0 mol of MnO, and AZrO ₃
Up to 4.0 mol (however, A is Ba, Sr and Ca
At least one of the above) is added and contained, and further, the above components are added as 100 parts by weight, and Li ₂ O-M ₁ O-M ₂ O
(Ti, Si) O ₂ (However, M ₁ is a small amount of Zn and Mn.
At least one type, M ₂ is Ba, Sr, Ca and Mg
And at least one kind), Li ₂ O: _{2 to} 45 mol% M ₁ O: 0 to 40 mol% M ₂ O: 5 to 40 mol% (Ti, Si) O ₂ : 35 to 70 mol % (However, the SiO ₂ component of (Ti, Si) O ₂ is 15
Oxide glass in the composition range of 0.2 to
A monolithic ceramic capacitor, which is made of a material containing 3.0 parts by weight, and in which the internal electrodes are made of nickel or a nickel alloy. 2. The monolithic ceramic capacitor according to claim 1 , wherein 100 parts by weight of the oxide glass is added and at least one of the following components is added. (1) 20 parts by weight or less of Al ₂ O ₃ (2) 10 parts by weight or less of ZrO ₂ Wherein the external electrodes, claim, characterized in that it is constituted by a sintered layer of conductive metal powder with added conductive metal powder or glass frit 1 or請<br/> Motomeko 2 laminated ceramic wolfberry capacitor as claimed in. 4. The external electrode comprises a first layer made of a sintered layer of conductive metal powder or conductive metal powder to which glass frit is added, and a second layer made of a plated layer thereon. laminated ceramic wolfberry capacitor according to claim 1 or claim 2, characterized.