JP2000026161A - Dielectric ceramic composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a dielectric ceramic compsn. based on BaTiO3, less liable to deteriorate the insulation resistance in mass firing in a neutral or reducing atmosphere and having a high dielectric constant, a low temp. variation of the capacitance and high reliability. SOLUTION: The dielectric ceramic compsn. is obtd. by adding BaO or BaCO3 to 100 mol BaTiO3 in such an amt. as to give a Ba to Ti ratio of 1.001-1.04, adding 0.5-5.0 mol MgO, 0.1-3.0 mol Y2O3, 0.01-0.4 mol MnO2 and 0.6-5.0 mol BaSiO3 compd. and further adding 0.01-0.26 mol (expressed in terms of V2O5) V atoms and 0.1-3.0 mol (expressed in terms of Al2O3) Al atoms.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a dielectric ceramic composition for a multilayer ceramic capacitor (hereinafter, referred to as a multilayer capacitor) using a base metal such as nickel for an internal electrode.

[0002]

2. Description of the Related Art A multilayer capacitor is manufactured by cutting a laminate in which a plurality of internal electrodes and ceramic green sheets are alternately laminated into a predetermined shape, and then firing the laminate integrally.

Conventionally, Pd or a Pd alloy has been used as the internal electrode material. However, since Pd is expensive,
In recent years, relatively inexpensive base metal materials such as Ni have been used.

[0004]

When a base metal material is used as the internal electrode material, the internal electrode is oxidized if it is integrally fired with a dielectric material in the air. Therefore, firing is performed in a neutral atmosphere or a reducing atmosphere. Must be done in However, when the conventional dielectric material is fired in a reducing atmosphere, the dielectric is reduced, the insulation resistance is reduced, and desired characteristics cannot be obtained. As a countermeasure, Japanese Patent Application Laid-Open No. 61-155255 proposes a reduction-resistant dielectric porcelain composition. A multilayer ceramic capacitor using this reduction-resistant dielectric porcelain composition has an insulation resistance characteristic (IR (Lifetime characteristic) is greatly deteriorated.

The dielectric composition of the present invention provides a dielectric ceramic composition which can provide a highly reliable multilayer capacitor with little deterioration in insulation resistance characteristics even when fired in a neutral or reducing atmosphere. The purpose is to do so.

[0006]

In order to solve the above-mentioned problems, the present invention provides a method in which Ba / T is added to 100 moles of BaTiO _3.
BaO or BaCO ₃ is added so that the i ratio becomes 1.001 to 1.04, and MgO is added to 0.5 to 5.0 mol,
Y ₂ O ₃ 0.1 to 3.0 moles, 0.01 and MnO ₂
By adding 0.4 mol and 0.6 to 5.0 mol of BaSiO ₃ , a highly reliable multilayer capacitor can be obtained without deterioration of insulation resistance characteristics even when firing in a neutral or reducing atmosphere. It can provide body device materials.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The invention according to claim 1 of the present invention
Is BaTiO_ThreeFor 100 moles, the Ba / Ti ratio is
BaO or Ba so as to be 1.001 to 1.04
CO_ThreeIs added, and 0.5 to 5.0 mol of MgO is further added.
Y_TwoO_Three0.1-3.0 mol, MnO_TwoFrom 0.01 to
0.4 mol, BaSiO_Three0.6 to 5.0 mol of
A dielectric porcelain composition characterized by comprising:
Excessive BaO added to adjust the Ba / Ti ratio of
Or BaCO_ThreeAnd MnO_TwoIndicates the reduction resistance of the dielectric composition.
Strengthening, especially MnO_TwoAddition in a neutral atmosphere or
During firing in a reducing atmosphere, the dielectric porcelain composition
In addition to preventing deterioration of insulation resistance characteristics,
A homogeneous sintered body can be obtained by suppressing variation in capacitance
effective. MgO, Y _TwoO_ThreeAddition of dielectric constant and capacitance
The effect of satisfying electrical characteristics such as temperature characteristics and electrostatic tangent
Fruit, BaSiO_ThreeIs relatively low firing temperature
Promotes sintering of the dielectric composition and obtains a dense sintered body
To stabilize insulation resistance and satisfy electrical performance.
It has the effect of being able to

According to the invention of claim 2 of the present invention, aluminum atoms are converted to Al ₂ O ₃ , and BaTiO ₃ 100
A dielectric ceramic composition according to claim 1, characterized in that 0.1 to 3.0 mol per mol moles, Al ₂
The addition of O ₃ has the effect of forming a uniform component phase in the firing process, and stabilizes sinterability and electrical characteristics.

The invention according to claim 3 of the present invention is characterized in that vanadium atoms are converted to V ₂ O ₅ and 0.01 mol to 0.26 mol is added to 100 mol of BaTiO _3. Item 3. The dielectric ceramic composition according to Item 1 or 2, wherein the addition of V ₂ O ₅ suppresses the reduction of TiO _2, a basic component that is easily reduced by firing in a reducing atmosphere, and reduces the insulation resistance of the multilayer capacitor. This has the effect of preventing the occurrence of a multilayer capacitor having small capacitance variations.

(Embodiment 1) First, BaO, Y ₂ O ₃ , MgO, MnO ₂ , and BaS are used with respect to 100 moles of BaTiO ₃ as starting materials so as to have a composition shown in (Table 1).
Each of iO ₃ is weighed, pure water is added to these starting materials, and wet mixing and pulverization is performed for 17 hours by a ball mill using partially stabilized zirconia balls as a medium, followed by dehydration drying. B
For aTiO ₃ and BaSiO ₃ , finely pulverized materials synthesized in advance by a solid phase method were used. In Table 1, the sample N
o. Those marked with * are outside the scope of the present invention, but are shown for comparison.

[0011]

[Table 1]

Next, the dehydrated and dried mixed material was crushed, passed through a 32-mesh sieve, put into an alumina crucible, and calcined at a temperature of 1100 ° C. for 2 hours. At this time, if the calcining temperature is too high, the capacitance-temperature change rate of the capacitance of the obtained multilayer capacitor may be too large, and care must be taken.

Next, the calcined raw material is wet-pulverized in a ball mill in the same manner as in the mixing so that the average particle size is 1.0 μm or less, and then dehydrated and dried and passed through a 32 mesh sieve to remove the dielectric ceramic material. Obtained.

A polyvinyl butyral resin as a binder, n-butyl acetate as a solvent, and dibutyl phthalate as a plasticizer were added to this dielectric ceramic material, and mixed with a yttria partially stabilized zirconia ball in a ball mill for 72 hours to prepare a slurry.

Using the obtained slurry, a dielectric ceramic green sheet (hereinafter, referred to as a green sheet) was formed on a polyester film using a known doctor blade method.

An internal electrode paste containing Ni as a main component is printed on a surface of the produced green sheet by a screen and dried. A plurality of the green sheets on which the Ni internal electrode pastes are printed are stacked and thermocompression-bonded according to a known method for manufacturing a multilayer capacitor to form a green multilayer body, and then a 3.3 mm × 1.7 mm multilayer capacitor green chip (hereinafter referred to as a “green chip”). (Referred to as green chips).

[0017] These green chips are mixed with zirconia bedding powder, and 10,000 pieces are put into an alumina-based sheath.
After removing the binder in a nitrogen-mixed air atmosphere at a temperature of 12 hours, and then using a mixed green gas of nitrogen and hydrogen in a reducing atmosphere in which Ni whose oxygen concentration is adjusted is not oxidized, at a temperature of 1220 to 1340 ° C. And sintering for 2 hours. After that, the sintered body of the multilayer capacitor is kept at 900 ° C. for 1 hour in an atmosphere adjusted with nitrogen, hydrogen, and oxygen in a cooling and cooling process, and then reoxidized. Produced. The firing temperature of each composition is
The optimum firing temperature at which the density of the sintered body of each composition was maximized in the temperature range of 1,220 to 1,340 ° C was used.

Next, after the obtained multilayer capacitor sintered body is barrel-polished, an external electrode paste containing Cu as a main component is sintered so as to be electrically connected to the internal electrode exposed on the end face of the sintered body. After being applied to the body end surface, the atmosphere was adjusted to 85% in an atmosphere in which the oxygen concentration was adjusted with a mixed green gas of nitrogen and hydrogen.
Baking was performed at 0 ° C. for 15 minutes to form external electrodes.

A nickel film was formed on the surface of the formed external electrode by electrolytic plating, and a solder film was further formed on the surface of the nickel film to complete a multilayer capacitor.

The multilayer capacitor thus obtained is
° C (room temperature), dielectric constant at 1 kHz frequency, dielectric loss tangent (tan δ), capacitance temperature change rate (change rate of capacitance with respect to capacitance of 20 ° C between -55 and + 125 ° C), and DC voltage of 25 V at room temperature. The insulation resistance (IR) when the voltage was applied was measured, and the results are shown in (Table 2). Further, as a standing test, the multilayer capacitor was heated to 150 ° C.
After holding for 1 hour in a constant temperature bath and returning to room temperature, the capacitance (C) of the capacitance (C) when left at room temperature for 48 hours as a reference and then the difference (ΔC) from the capacitance after 1000 hours at room temperature Change with time of capacity (ΔC / C), 12 as accelerated life test
Degradation of insulation resistance after continuous application of a voltage of 200 V DC at a temperature of 5 ° C. for 250 hours (IR of 100 samples
× 10 ⁷ Ω or less which was counted as defective), and the variation in capacitance as initial characteristics (Table 3)
Is shown in In addition, the sample No. of (Table 2) and (Table 3). Are common to (Table 1), and the same numbers are samples having the same composition.

[0021]

[Table 2]

[0022]

[Table 3]

As apparent from (Table 2) and (Table 3),
Dielectric composition according to the present invention (Sample Nos. 3, 4, 6, 9)
~ 12,15 ~ 18,21 ~ 24,28 ~ 31) have an initial performance of a high dielectric constant of 2300 or more, a small variation in capacitance within ± 5%, and a small rate of change in capacitance temperature ±.
15% or less and insulation resistance (IR) is 1 × 10 ¹² Ω
And no deterioration was observed. Further, the rate of change with time in capacitance in the standing test was as small as -1.0 to -1.3%, and it was found that no subcomponent phase was generated inside the sintered body. On the other hand, if the Ba / Ti ratio of the main component is smaller than 1.001 (Sample Nos. 1 and 2), the material is reduced by firing in a reducing atmosphere to be a semiconductor, and conversely, the Ba / Ti ratio becomes 1.04.
(Sample No. 5), the dielectric sintering becomes insufficient, and if it exceeds 5 moles (Sample No. 8), the rate of temperature change of the multilayer capacitor becomes large, and
The rate of change with time in capacitance is undesirably large. Y ₂
When the added amount of O ₃ is less than 0.1 mol (Sample No. 13)
The rate of change in capacitance with temperature increases, and the rate of change in capacitance with time and tan δ also increase. Conversely, if it exceeds 3 moles (Sample No. 14), the dielectric constant decreases and is not practical. If the added amount of MnO ₂ is less than 0.01 mol (sample N
o. 19) The sintered body is partially converted into a semiconductor, and the initial capacitance variation is large, and the insulation resistance value is small.
As a result, the insulation resistance value is significantly deteriorated in the accelerated life test. If the amount exceeds 0.4 mol (sample N
o. 20) The rate of change of capacitance with temperature and change with time is large, and the deterioration of insulation resistance is also large. If the amount of BaSiO ₃ added is less than 0.6 mol (Sample Nos. 25 and 2
6) Sufficient sintered body density cannot be obtained, resulting in variations in capacitance and insulation resistance, which is not practical. On the other hand, when the addition amount exceeds 5.0 mol (Sample No. 27)
Although the sinterability is improved, the dielectric constant is lowered, and the rate of change in capacitance with temperature is increased, which is not practical.

From the above results, the main component of BaTiO ₃ 10
BaO has a Ba / Ti ratio of 1.001 to
By adding excessively so as to be 1.04, a good sintered body can be obtained without the dielectric being reduced in large-scale firing in a reducing atmosphere. By adding 0.5 to 5.0 mol of MgO as to reduce the temperature change of the dielectric constant, has the effect of improving the insulation resistance value, the Y ₂ O ₃ is added 0.1 to 3.0 molar This has the effect of reducing the capacitance temperature change and improving the insulation resistance value.
Further, by adding 0.01 to 0.4 mol of MnO ₂ , reduction of TiO ₂ of BaTiO _{3 as} a main component can be prevented and insulation resistance characteristics can be improved. BaSiO ₃ was added at 0.
By adding 6 to 5.0 moles, sintering is promoted and firing at a relatively low temperature becomes possible, and it is clear that there is an effect of reducing variations in capacitance and insulation resistance.

However, if the amount of each additive is out of the range of the present invention, the dispersion of the electric characteristics tends to increase, and the rate of change of the capacitance with temperature tends to increase. Although fine powders of BaTiO ₃ and BaSiO ₃ compounds previously prepared by a solid phase method were used, it has been confirmed that similar results can be obtained by using compounds prepared by a method other than the solid phase method.

(Embodiment 2) First, BaTiO ₃ 10
0.02 mol of BaCO ₃ and MgO of 2. mol per 0 mol.
5 mol, 1.0 mol of Y ₂ O ₃ , 0.2 mol of MnO ₂ ,
The amounts of Al ₂ O ₃ and V ₂ O ₅ shown in (Table 4) are each weighed and added to the one containing 2.1 mol of the BaSiO ₃ compound.

[0027]

[Table 4]

Next, after obtaining a dielectric material powder under the same conditions as in the first embodiment, a multilayer capacitor was manufactured. However, at the time of baking, the filling amount of green chips per sheath was set to 15,000 pieces, which is 1.5 times that of the first embodiment, and the other conditions were the same as those of the first embodiment.
The test was performed in the range of 0 to 1340 ° C.

Thereafter, the multilayer capacitor obtained in the same manner as in the first embodiment was evaluated, and the results are shown in (Table 5) and (Table 6).

[0030]

[Table 5]

[0031]

[Table 6]

As shown in Tables 5 and 6, BaT
iO ₃ 100 mol of BaCO ₃ 0.02 mol, Mg
2.5 mol of O, 1.0 mol of Y ₂ O ₃ and 0.1 mol of MnO ₂ .
2 mol, the composition obtained by adding 2.1 mol of BaSiO ₃ compound, further V ₂ O ₅ and from 0.01 to 0.26 mol per mol of the added composition (Sample Nanba32～34,37,38) is
At the time of firing, the V atoms contained in V ₂ O ₅ suppress the reduction of TiO _{2 in} the main component, even if the amount of sheath is increased,
An excellent multilayer capacitor having high insulation resistance and no deterioration of insulation resistance can be obtained. At this time, the added amount of V ₂ O ₅ was 0.26.
If it exceeds mol (exceeding 0.52 mol as V atom) (Sample No. 36), the rate of change of capacitance with temperature will increase and the rate of change with time of capacitance will also increase. In addition, less than 0.01 mol (as a V atom,
If it is less than 0.02 mol (Sample No. 35), when it is fired in a large amount, the insulation property varies, and the insulation resistance deteriorates. On the other hand, the composition in which 0.1 to 3.0 mol of Al ₂ O ₃ was added (Sample Nos. 32 to 35, 37, 38, and 0.2 to 6.0 mol as Al atoms) was added. Promotes sintering, and it is possible to obtain a uniform sintered body free from the generation of subcomponent phases which are likely to occur in a multicomponent composition as in the present invention. On the other hand, when the addition amount exceeds 3.0 mol (Sample No. 40), the rate of change in capacitance with temperature and the dielectric loss (ta)
nδ) is undesirably large, and if it is less than 0.1 mol (Sample No. 39), the generation of subcomponent phases increases, and a uniform sintered body cannot be obtained.

From the above results, BaTiO ₃ of the present invention is used as a main component, and BaCO ₃ , MgO, Y ₂ O ₃ , Mn
By adding V ₂ O ₅ as a V atom to the composition to which O ₂ and BaSiO ₃ are added, reduction of the dielectric is prevented even in mass firing in a reducing atmosphere to improve the insulation resistance performance, and Al atom is added. It is clear that the addition of Al ₂ O ₃ suppresses the generation of the subcomponent phase, obtains a uniform sintered body, and obtains a multilayer capacitor having good electric characteristics.

[0034]

As described above, according to the present invention, BaTiO_Three1
The ratio of Ba / Ti is 1.001 to 1.04 with respect to 00 mol.
BaO, BaCO to become_ThreeAnd further Mg
O is 0.5 to 5.0 mol, Y_TwoO_Three0.1 to 3.0
MnO_TwoFrom 0.01 to 0.4 mol, BaSiO_ThreeCompound
Atmosphere by adding 0.6 to 5.0 moles of the product
When firing at a relatively low temperature in the air, the electrical characteristics are stable.
Excellent dielectric ceramic composition for multilayer capacitors can be obtained
Therefore, even when a base metal material is used for the internal electrode material,
It can be fired integrally with the body. Also V
Child, Al atom to V _TwoO_Five, Al_TwoO_ThreeTo be added as
Smell in mass firing in neutral or reducing atmosphere
Can prevent dielectric reduction and promote firing
To obtain a uniform sintered body.
Variation in capacitance and capacitance temperature change rate
Will be excellent.

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 4G031 AA03 AA06 AA08 AA11 AA13 AA19 AA29 BA09 GA02 5G303 AA01 AB01 AB06 AB11 AB20 BA12 CA01 CB01 CB03 CB17 CB18 CB30 CB35 CB36 CB40

Claims (3)

[Claims] 1. A BaTiO ₃ with respect to 100 moles, Ba /
BaO or BaCO ₃ is added so that the Ti ratio becomes 1.001 to 1.04, and MgO is further added to 0.5 to 5.0.
0 mol, 0.1 to 3.0 mol of Y ₂ O _3, the MnO ₂ 0.
01 to 0.4 mol, the dielectric ceramic composition characterized in that the BaSiO ₃ to 0.6 to 5.0 mol per mol. 2. The dielectric ceramic composition according to claim 1, wherein the aluminum atom is converted to Al ₂ O _3, and 0.1 to 3.0 mol is added to 100 mol of BaTiO ₃ . . 3. Converting a vanadium atom to V ₂ O ₅ ,
aTiO ₃ 100 0.01 mol per mol ～0.26
3. The method according to claim 1, wherein the compound is added in a molar amount.
3. The dielectric ceramic composition according to item 1.