JP3438334B2 - Non-reducing dielectric porcelain composition - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a non-reducing dielectric porcelain composition, and more particularly to a non-reducing dielectric porcelain composition for use in, for example, laminated ceramic capacitors.

[0002]

2. Description of the Related Art In the process of manufacturing a monolithic ceramic capacitor, first, a sheet-shaped dielectric material is prepared by coating an electrode material for forming internal electrodes on the surface thereof. As the dielectric material, for example, a material containing BaTiO ₃ as a main component is used. A sheet-shaped dielectric material coated with this electrode material is laminated, thermocompression bonded, and the integrated product is fired at 1250 to 1350 ° C. in a natural atmosphere to obtain a dielectric ceramic having internal electrodes. Then, an external electrode that is electrically connected to the internal electrode is printed on the end surface of the dielectric ceramic to obtain a monolithic ceramic capacitor.

Therefore, the material for the internal electrodes must satisfy the following conditions.

(A) Since the dielectric porcelain and the internal electrodes are fired at the same time, the dielectric porcelain must have a melting point 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 alloys thereof have been used as the electrode material 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 precious metals
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 that it is remarkably reduced when it is fired in such a reducing atmosphere and becomes a semiconductor.

In order to overcome such drawbacks, for example, as shown in Japanese Patent Publication No. 57-42588, in a barium titanate solid solution, the barium site / titanium site ratio is set to be more than stoichiometric. The body material was devised. 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 that uses a base metal such as nickel as an internal electrode. Became.

[0010]

With the recent development of electronics, miniaturization of electronic parts has rapidly progressed, and the tendency of miniaturization of monolithic ceramic capacitors has become remarkable. As a method for miniaturizing the monolithic ceramic capacitor, it is generally known to use a material having a large dielectric constant or to thin the dielectric layer. However, a material having a large dielectric constant has a large number of crystal grains, and when the film is a thin film having a thickness of 10 μm or less, the number of crystal grains present in one layer decreases, and reliability decreases.

On the other hand, as disclosed in Japanese Patent Laid-Open No. 61-101459, a solid solution of barium titanate with La, N is used.
There is known a non-reducing dielectric ceramic having a small crystal grain size, to which a rare earth oxide such as d, Sm or Dy is added. By thus reducing the crystal grain size, the number of crystal grains present in one layer can be increased.

However, materials containing these rare earth oxides cannot provide a large dielectric constant, and are easily reduced during firing, which is problematic in terms of reliability.

Therefore, the main object of the present invention is that even if it is fired in a reducing atmosphere, it does not become a semiconductor and, despite its small crystal grain size, a large dielectric constant is obtained. It is an object of the present invention to provide a non-reducing dielectric ceramic composition capable of miniaturizing a monolithic ceramic capacitor.

[0014]

This invention SUMMARY OF], the main component the following composition _{formula, {(Ba 1-opqr Sr} o Ca p R1 q
_{R2 r) O 1 + q /} 2 + r / 2} m (Ti 1-xy Zr x Hf y)
O ₂ (wherein R1 is at least one selected from La, Ce and Nd, and R2 is Dy, Ho, Er, Y
b, and at least one selected from Y), and o, p, q, r, x, y, and m are 0 <o ≦ 0.
32, 0 < p ≦ 0.20, 0 <q ≦ 0.02, 0 <r ≦
0.02, 0 <x ≦ 0.24, 0 <y ≦ 0.16, 1.
The relationship of 00 ≦ m ≦ 1.03 and 0 <q + r ≦ 0.03 is satisfied, and Mn, Fe, and C are added to 100 mol of the main component.
The oxides of r, Co and Ni were replaced with MnO, Fe ₂ O ₃ and Cr.
When expressed as ₂ O ₃ , CoO, and NiO, the non-reducing dielectric ceramic composition contains at least one kind of each oxide in a total amount of 0.02 to 2.0 mol.

Further , in the present invention, the main components are as follows:
Formula, {(Ba _1-oqr Sr _o R1 _q R2 _r ) O _{1 + q / 2 + r / 2
} M (Ti 1-xy Zr} x Hf y) O 2 ( however, R1
Is at least one selected from La, Ce and Nd
Type, R2 is from Dy, Ho, Er, Yb and Y
At least one selected), o, q, r,
x, y and m are 0 <o ≦ 0.32, 0 <q ≦ 0.0
2, 0 <r ≦ 0.02, 0 <x ≦ 0.24, 0 <y ≦
0.16, 1.00 ≦ m ≦ 1.03, 0 <q + r ≦ 0.
Satisfying the relation of 03, and for 100 moles of the main component,
The oxides of Mn, Fe, Cr, Co, and Ni are replaced with MnO and F.
e ₂ O ₃ , Cr ₂ O ₃ , CoO, NiO,
The total amount of at least one kind of each oxide is 0.02 to 2.
It is a non-reducing dielectric ceramic composition containing 0 mol.

[0016]

According to the present invention, it is possible to obtain a non-reducing dielectric ceramic composition which is not reduced even when fired in a reducing atmosphere and does not become a semiconductor. Therefore, if a porcelain multilayer capacitor is manufactured using this non-reducing dielectric porcelain composition, a base metal can be used as an electrode material.
Since it can be fired at a relatively low temperature of 300 ° C. or lower, the cost of the monolithic ceramic capacitor can be reduced.

Further, in the porcelain using this non-reducing dielectric ceramic composition, the dielectric constant is 9000 or more, and despite having such a high dielectric constant, the crystal grain is 3 μm.
Below is small. Therefore, when a multilayer ceramic capacitor is manufactured, even if the dielectric layer is thinned, the amount of crystal grains existing in the layer does not decrease unlike the conventional multilayer ceramic capacitor. Therefore, it is possible to obtain a highly reliable, small-sized, large-capacity monolithic ceramic capacitor.

The above and other objects, features and advantages of the present invention will become more apparent from the detailed description of the embodiments below.

[0019]

【Example】

(Example 1) First, as starting materials, BaCO ₃ , SrCO ₃ , CaCO ₃ , CeO ₂ , with a purity of 99.8% or more,
La ₂ O ₃ , Nd ₂ O ₃ , Dy ₂ O ₃ , Ho ₂ O ₃ , E
r ₂ O ₃ , Yb ₂ O ₃ , Y ₂ O ₃ , TiO ₂ , ZrO
₂ , HfO ₂ , MnO, Fe ₂ O ₃ , Cr ₂ O ₃ , Co
O and NiO were prepared. These raw materials are {(Ba
_{1-opqr Sr o Ca p R1} q R2 r) O 1 + q / 2 + r / 2}
expressed by a composition formula _{m (Ti 1-xy Zr x} Hf y) O 2,
O, p, q, r, m, x and y were blended so as to have the ratios shown in Table 1 and Table 2 to obtain blended raw materials. The blended raw materials were wet mixed in a ball mill, pulverized, dried, and calcined in air at 1100 ° C. for 2 hours to obtain a calcined product. This calcined product was crushed with a dry crusher to obtain a particle size of 1
A pulverized product having a size of not more than μm was obtained. Pure water and a vinyl acetate binder were added to this pulverized product, and the mixture was mixed for 16 hours with a ball mill to obtain a mixture.

[0020]

[Table 1]

[0021]

[Table 2]

After this mixture was dry granulated, 2000 k
Molded with a pressure of g / cm ² , diameter 10 mm, thickness 0.5
A disc of mm was obtained. The resulting disk is 50 in air
After heating to 0 ° C. to burn the organic binder, H ₂ —N ₂ having an oxygen partial pressure of 2 × 10 ^{−10 to} 3 × 10 ⁻¹² atm.
-In a reducing atmosphere furnace composed of air gas, firing was performed for 2 hours at the temperatures shown in Tables 3 and 4 to obtain a disk-shaped porcelain.
The surface of the obtained porcelain was magnified 150 with a scanning electron microscope.
Observation was carried out at 0 times and the grain size was measured.

[0023]

[Table 3]

[0024]

[Table 4]

Then, a silver electrode was baked on the main surface of the obtained porcelain at a temperature of 600 ° C. in an N ₂ atmosphere to obtain a measurement sample (capacitor). The rate of change of the dielectric constant (ε) at room temperature, the dielectric loss (tan δ), and the capacitance (C) with respect to temperature changes was measured for the obtained sample. The dielectric constant and the dielectric loss are 25 ° C and 1k.
It was measured under the conditions of Hz and 1 V _rms . Regarding the rate of change of the capacitance with respect to temperature change, the rate of change at −25 ° C. and 85 ° C. (ΔC /
C ₂₀ ) and a value (| ΔC / C ₂₀ | _max ) at which the rate of change is maximum as an absolute value within the range of −25 ° C. to 85 ° C.

Furthermore, by means of an insulation resistance tester, 50
The insulation resistance value was measured after a direct current of 0 V was applied for 2 minutes. The insulation resistance was measured at 25 ° C. and 85 ° C., and the logarithm (logρ) of each volume resistivity was calculated. The results of these measurements are shown in Tables 3 and 4.

Next, the reasons for limiting each composition will be described.

[0028] _{{(Ba 1-opqr Sr o} Ca p R1 q R
_{2 r) O 1 + q /} 2 + r / 2} m (Ti 1-xy Zr x Hf y) O
_In Sample ₂ , when the Sr amount o is 0 as in Sample No. 1, the dielectric constant is less than 11,000, the dielectric loss exceeds 2.0%, and the rate of change in capacitance with temperature is large, which is not preferable. On the other hand, as in sample No. 18, the Sr amount o is 0.32
When it exceeds, the dielectric constant is less than 11,000 and the temperature change rate of the capacitance does not satisfy the F characteristic of JIS standard, which is not preferable.

When the Ca content p exceeds 0.20 as in sample No. 19, the sinterability deteriorates and the dielectric constant decreases, which is not preferable.

Further, as in Sample No. 2, when the R1 amount q is 0, the crystal grain size becomes larger than 3 μm, and in the case of a laminated ceramic capacitor, the dielectric layer cannot be thinned, which is not preferable. On the other hand, as in Sample No. 20, the R1 amount q
When exceeds 0.02, the dielectric loss exceeds 2.0% and 2
The insulation resistance at 5 ° C and 85 ° C decreases, which is not preferable.

When the R2 amount r is 0 as in Sample No. 3, the dielectric constant is less than 11,000 and the rate of change in capacitance with temperature is large, which is not preferable. On the other hand, when the R2 amount r exceeds 0.02 as in Sample No. 21, the dielectric loss is 2.0.
%, The insulation resistance decreases, which is not preferable.

When the sum q + r of the R1 amount q and the R2 amount r exceeds 0.03 as in the sample No. 22, the porcelain is reduced when it is fired in a reducing atmosphere to become a semiconductor, and the insulation resistance is increased. It is not preferable because it significantly decreases.

Further, when the Zr amount x is 0 as in Sample No. 4, the dielectric constant becomes less than 11000, and the temperature change rate of the capacitance becomes large, which is not preferable. On the other hand, when the Zr amount x exceeds 0.24 as in Sample No. 23, the sinterability decreases and the dielectric constant becomes less than 11000, which is not preferable.

When the Hf amount y is 0 as in Sample No. 5, the dielectric constant is less than 11000, which is not preferable. When the Hf amount y exceeds 0.16 as in Sample No. 24, the temperature change rate of capacitance does not satisfy the JIS standard F characteristics, which is not preferable.

In addition, like sample number 7, {(Ba
_{1-opqr Sr o Ca p R1} q R2 r) O 1 + q / 2 + r / 2}
The molar ratio m of _m (Ti _1-xy Zr _x Hf _y ) O ₂ is 1.0.
If it is less than 0, the porcelain is reduced when fired in a reducing atmosphere, and it becomes a semiconductor to lower the insulation resistance, which is not preferable. On the other hand, as in Sample No. 26, the molar ratio m was 1.
If it exceeds 03, the sinterability is extremely deteriorated, which is not preferable.

Further, as in Sample No. 6, MnO, Fe ₂ O ₃ , Cr ₂ O ₃ , CoO and N as additives were added.
If the amount of iO added is less than 0.02 mol, the insulation resistance at 85 ° C. or higher becomes small, and the reliability of long-term use at high temperatures is reduced, which is not preferable. On the other hand, as in Sample No. 25, when the amount of these additives exceeds 2.0 mol, the dielectric loss exceeds 2.0% and increases, and at the same time, the insulation resistance deteriorates, which is not preferable.

On the other hand, when the non-reducing dielectric ceramic composition of the present invention is used, the dielectric constant is as high as 11000 or more, the dielectric loss is 2.0% or less, and the rate of change in capacitance with temperature is It is possible to obtain a dielectric porcelain satisfying the F characteristic standard defined in JIS in the range of -25 ° C to 85 ° C. Furthermore, in this dielectric porcelain, the insulation resistance at 25 ° C. and 85 ° C. is 1 when expressed as the logarithm of the volume resistivity.
It shows a high value of 2 or more. Further, the non-reducing dielectric ceramic composition of the present invention can be sintered at a relatively low firing temperature of 1300 ° C. or less, and has a small particle size of 3 μm or less.

[0038]

[0039]

[0040]

[0041]

[0042]

[0043]

[0044]

[0045]

[0046]

[0047]

[0048]

[0049]

[0050]

[0051]

[0052]

[0053]

[0054]

[0055]

[0056]

[0057]

[0058]

( Example 2 ) First, the dielectric materials having the particle sizes of sample numbers 2, 3, 15, and 17 of Example 1 having a particle size of 1 μm or less were prepared. In addition, as a starting material, BaCO ₃ , SrCO ₃ having a purity of 99.8% or more,
CaCO ₃ , TiO ₂ , ZrO ₂ , HfO ₂ , MnO,
NiO was prepared. 100 mol {(Ba
_0.92 Sr _0.06 Ca _0.02 ) O} _1.01 (Ti _0.83 Zr _0.16 H
f _0.01 ) O ₂ +0.3 mol MnO + 0.1 mol Ni
The ingredients were blended so that the composition ratio of O was adjusted to obtain a blended raw material. The blended raw materials were wet mixed in a ball mill, pulverized, dried, and calcined in air at 1100 ° C. for 2 hours to obtain a calcined product. This calcined product was crushed by a dry crusher, and a dielectric material having a particle size of 1 μm or less was prepared as a comparative material 1.

A polyvinyl butyral binder and an organic solvent such as ethanol were added to this raw material powder and wet-mixed by a ball mill to prepare a ceramic slurry. After that, the ceramic slurry was formed into a sheet by a doctor blade method to obtain a rectangular green sheet having a thickness of 18 μm. Next, a conductive paste containing Ni as a main component was printed on this ceramic green sheet to form a conductive paste layer for forming internal electrodes. 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. The obtained 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 2 × 10 ^{−10 to} 3 × 10 ^−12.
atm of H ₂ -N ₂ - calcined for 2 hours at a temperature shown in Table 10 in a reducing atmosphere consisting of air gas, to obtain a ceramic sintered body. The surface of the obtained ceramic sintered body was observed with a scanning electron microscope at a magnification of 1,500, and the grain size was measured.

[0061]

[Table 5]

After firing, Ag paste was applied to both end faces of the obtained 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. The external dimensions of the thus-obtained monolithic ceramic capacitor are 1.6 mm in width, 3.2 mm in length,
The thickness is 1.2 mm, and the thickness of the dielectric ceramic layer interposed between the internal electrodes is 15 μm. The total number of effective dielectric ceramic layers is 19, and the area of the counter electrode per layer is 2.1 mm ² .

Capacitance (C) and dielectric loss (tan)
δ) is a frequency of 1 kHz using an automatic bridge type measuring instrument
The measurement was performed at z, 1 V _rms , and 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 was applied for 2 minutes using an insulation resistance meter to measure the insulation resistance (R) at 25 ° C. and 85 ° C. The product of (C) and 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. The rate of change in capacitance with respect to temperature change was based on the capacitance at 20 ° C.
The rate of change (ΔC / C ₂₀ ) at 5 ° C. and 85 ° C. is shown. As a high temperature load life test, 36 pieces of each sample and a temperature of 15
A direct current voltage of 150 V was applied at 0 ° C., and the change with time of the insulation resistance was measured. As the high temperature load test, 36 samples of each sample were applied with a DC voltage of 32 V at a temperature of 85 ° C., and the capacitance (C) after 1000 hours was measured.
In the high temperature load life test, the time when the insulation resistance (R) of each sample was 10 ⁶ Ω or less was defined as the life time, and the average value of 36 samples was shown as the mean life time.
Further, in the high temperature load test, the change rate ((C ₁₀₀₀ -C ₀ / C ₀ × 100)) of the capacitance (C ₁₀₀₀ ) after 1000 hours elapsed with respect to the capacitance (C ₀ ) before the test was 36. The average value is shown in Table 5. The results of the above tests are shown in Table 5 .

As is apparent from Table 5 , the laminated ceramic capacitor using the non-reducing dielectric ceramic composition of the present invention has a high dielectric constant (ε) and a small dielectric loss (tan δ). In addition, the rate of change in capacitance with respect to temperature changes (ΔC
/ C ₂₀ ) satisfies the F characteristic standard defined in JIS in the range of -25 ° C to 85 ° C. Moreover, 25 ℃, 85 ℃
Insulation resistance in 1) shows a high value of 10000 MΩ · μF, 5000 MΩ · μF or more, respectively, when expressed by the CR product. Further, the high temperature life time is as long as 100 hours or more, and the change in capacitance before and after the high temperature load test of 1000 hours is as small as 10% or less. Furthermore, the firing temperature is 1300
It can be sintered at a relatively low temperature of ℃ or less, and the particle size is as small as 3 µm or less.

On the other hand, La, Ce, Nd, Pr,
The multilayer ceramic capacitor of Sample No. 2 using the non-reducing dielectric ceramic composition in which the amount of R1 is 0, which is composed of at least one selected from Sm, has a high temperature load life time of It will be shorter than 100 hours. Further, in the case of Sample No. 3 outside the scope of the present invention, a non-reducing dielectric porcelain composition having an R2 content of 0 composed of at least one kind selected from Dy, Ho, Er, Yb and Y was used. The monolithic ceramic capacitor has a low dielectric constant (ε) and a large dielectric loss (tan δ).
The change in electrostatic capacitance at 00 hours becomes large.

Furthermore, the multilayer ceramic capacitor of Comparative Raw Material 1 to which these R1 and R2 are not added is
The high-temperature load life time is short, and the change in capacitance becomes large after 1000 hours of high-temperature load test. That is, by adding R1 and R2 at the same time, it is possible to obtain a monolithic ceramic capacitor which has a long life under high temperature load and a small change in capacitance with time under high temperature load.

[0067]

[0068]

[0069]

[0070]

[0071]

[0072]

[0073]

[0074]

In the above examples, as the starting material,
BaCO ₃ , SrCO ₃ , CaCO ₃ , TiO ₂ , Zr
Although oxide powders such as O ₂ and HfO ₂ are used, the powders are not limited to these oxide powders, and powders produced by an alkoxide method, a coprecipitation method, or a hydrothermal synthesis method may be used. By using these powders, there is a possibility that the characteristics shown in this example will be improved.

In the non-reducing dielectric ceramic composition according to the present invention, the addition of a slight amount of a sintering aid such as silica or oxide glass does not impair the obtained characteristics.

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Claims (2)

(57) [Claims] 1. A main components the following composition formula _{{(Ba 1-opqr Sr o} Ca p R1 q R2 r) O
_{1 + q / 2 + r /} 2} m (Ti 1-xy Zr x Hf y) O 2 ( provided that at least one R1 is selected from among La, Ce and Nd, R2 is Dy, Ho, Er, Yb and Y
At least one selected from among), o,
p, q, r, x, y and m are 0 <o ≦ 0.32 0 < p ≦ 0.20 0 <q ≦ 0.02 0 <r ≦ 0.02 0 <x ≦ 0.24 0 < The relation of y ≦ 0.16 1.00 ≦ m ≦ 1.03 0 <q + r ≦ 0.03 is satisfied, and M is based on 100 moles of the main component.
The oxides of n, Fe, Cr, Co and Ni are replaced with MnO and Fe.
When expressed as ₂ O ₃ , Cr ₂ O ₃ , CoO, and NiO, the total amount of at least one kind of each oxide is 0.02 to 2.0.
A non-reducing dielectric ceramic composition containing a mole. 2. The following composition formula {(Ba _1-oqr Sr _o R1 _q R2 _r ) O _{1 + q / 2 + r / 2} } is the main component .
_{m (Ti 1-xy Zr x} Hf y) O 2 ( however, R1 L
at least one selected from a, Ce and Nd
R2 is selected from Dy, Ho, Er, Yb and Y.
At least one type), o, q, r, x,
y and m are 0 <o ≦ 0.32 0 <q ≦ 0.02 0 <r ≦ 0.02 0 <x ≦ 0.24 0 <y ≦ 0.16 1.00 ≦ m ≦ 1.03 0 <Q + r ≦ 0.03 is satisfied, and if 100 mol of the main component is satisfied, M
The oxides of n, Fe, Cr, Co and Ni are replaced with MnO and Fe.
When expressed as ₂ O ₃ , Cr ₂ O ₃ , CoO and NiO,
0.02 to 2.0 in total of at least one kind of oxide
A non-reducing dielectric ceramic composition containing a mole.