JP2000026160A - 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 low temp. mass firing in a neutral or reducing atmosphere and having a high dielectric constant, a low temp. variation of the static 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 Dy2O3, 0.01-0.4 mol MnO2 and 0.6-5.0 mol BaO-MgO-SiO2 compd. and further adding 0.01-0.26 mol V2O5 and 0.1-3.0 mol Al2O3.

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 green laminate in which a plurality of internal electrodes and dielectric ceramic green sheets are alternately laminated into a predetermined shape and then firing them integrally. Conventionally, Pd or a Pd alloy has been used for the internal electrode material. However, since Pd is expensive, a relatively inexpensive base metal material such as Ni has recently been used.

[0003]

When a base metal is used as a material for an internal electrode, if the firing is performed integrally with a dielectric material in the air, the internal electrode is oxidized and insulated. Need to be fired. When firing in a reducing atmosphere, the dielectric ceramic composition for a multilayer capacitor having Pd or a Pd alloy as an internal electrode is reduced in dielectric and has low specific resistance, so that desired characteristics cannot be obtained. As a countermeasure, Japanese Unexamined Patent Publication (Kokai) No. 61-155255 has proposed a reduction-resistant dielectric ceramic composition. A multilayer capacitor using this reduction-resistant dielectric ceramic composition has a
The insulation resistance characteristics (IR life characteristics) deteriorated greatly, and there was a problem in reliability.

[0004] Therefore, the dielectric ceramic composition of the present invention can provide a highly reliable multilayer capacitor with no deterioration in insulation resistance characteristics even when mass-fired in a neutral or reducing atmosphere. It is intended to provide a composition.

[0005]

According to the present invention, BaO is added to 100 mol of BaTiO ₃ so that the ratio of Ba / Ti becomes 1.001 to 1.04. MgO 0.5 to 5.0 mol, 0.1 to 3.0 mol of Dy ₂ O _3, the MnO ₂ 0.01 to 0.4 mol, the BaO · MgO · SiO ₂ compound 0.6 to 5 .0
By adding in a molar amount, a highly reliable multilayer capacitor having no deterioration in insulation resistance characteristics can be obtained even when firing in a neutral or reducing atmosphere.

[0006]

BEST MODE FOR CARRYING OUT THE INVENTION The invention described in claim 1 of the present invention is characterized in that BaO or B is added to 100 moles of BaTiO _3.
aCO ₃ was added so that the ratio of Ba / Ti became 1.001 to 1.04, and MgO was further added to 0.5 to 5.0 mol.
0.1-3.0 moles of y ₂ O _3, 0.01~ the MnO ₂
0.4 mol, 0.6 mol of BaO.MgO.SiO ₂ compound
This is a dielectric porcelain composition characterized in that it is added in an amount of up to 5.0 moles, and an excess of BaO or BaCO ₃ and MnO ₂ added to adjust the Ba / Ti ratio of the basic component is a property of the dielectric composition. The addition of MnO ₂ enhances the reducibility, and in particular, prevents the deterioration of the insulation resistance characteristics of the dielectric composition and reduces the variation in the capacitance of the multilayer capacitor during firing of the multilayer capacitor in a neutral or reducing atmosphere. There is an effect that a homogeneous sintered body can be obtained by suppressing this. MgO, Dy
The addition of ₂ O ₃ has the effect of satisfying electrical characteristics such as dielectric constant, capacitance temperature characteristics, and dielectric loss tangent.
The addition of the O.SiO ₂ compound promotes sintering of the dielectric composition even when the firing temperature is relatively low, so that a dense sintered body can be obtained, so that the insulation resistance can be stabilized and the electrical performance can be satisfied. It has an action.

According to a second aspect of the present invention, aluminum atoms are converted to Al ₂ O ₃ , and 0.1 to 3.0 mol is added to 100 mol of BaTiO _3. 2. The dielectric porcelain composition according to 1, wherein Al ₂ O ₃
Has the effect of forming a uniform component phase in the firing process, and stabilizes sinterability and electrical characteristics.

[0008] The invention according to claim 3 of the present invention, the claims in terms of vanadium atoms in V ₂ O _5, characterized by 0.01 to 0.26 mol added to BaTiO ₃ 100 moles 3. The dielectric ceramic composition according to 1 or 2,
The addition of V ₂ O ₅ suppresses the reduction of TiO ₂ , which constitutes the basic component BaTiO ₃ , which is easily reduced by firing in a reducing atmosphere, thereby preventing a decrease in the insulation resistance of the multilayer capacitor. It has the effect that it can be obtained.

An embodiment of the present invention will be described below. (Embodiment 1) First, 100 mol of BaTiO ₃ and B
aCO ₃ , Dy ₂ O ₃ , MgO, MnO ₂ , BaO.MgO
· SiO ₂ were weighed, pure water was added to these starting materials, after the ball mill for 17 hours wet mixing pulverization partially stabilized zirconia boulders as a medium, it is dehydrated and dried. The BaTiO ₃ and BaO.MgO.SiO ₂ compounds used were finely pulverized materials synthesized in advance by a solid phase method. In addition, samples with * added to the sample No. in the table are out of the scope of the present invention, but are described for comparison.

[0010]

[Table 1]

Next, the dehydrated and dried material is crushed, passed through a 32-mesh sieve, put into an alumina crucible, and put into a crucible.
Calcination was performed by holding at a temperature of 100 ° C. for 2 hours. At this time, if the calcination temperature is too high, the temperature change rate of the capacitance of the obtained multilayer capacitor may become too large, and care must be taken.

Next, the calcined 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 the dielectric ceramic material, and mixed with a partially stabilized zirconia ball in a ball mill for 72 hours to prepare a slurry.

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

An internal electrode paste containing Ni as a main component is screen-printed on the upper surface of the produced green sheet, and dried. A green sheet on which the Ni internal electrode paste is printed is stacked and thermocompressed to form a green laminate according to a known multilayer capacitor manufacturing method.
A multilayer capacitor green chip (hereinafter, referred to as a green chip) of 3.3 mm × 1.7 mm is cut.

[0016] These green chips are mixed with zirconia bedding powder, and 10,000 pieces are put in an alumina-based sheath. The binder is removed at 400 ° C. for 12 hours in a nitrogen-mixed air atmosphere. The firing is carried out at a temperature of 1220 ° C. to 1340 ° C. for 2 hours in a gas atmosphere. After that, the sintered body of the multilayer capacitor is cooled down to room temperature after being held in an atmosphere adjusted with nitrogen, hydrogen and oxygen for 1 hour at a temperature of 900 ° C. in a cooling and cooling process, and then cooled to room temperature. Produced. In addition, the firing temperature of each composition used the optimal firing temperature at which the density of the sintered body of each composition becomes maximum in the above temperature range of 1,220 to 1,340 ° C.

Next, after the obtained multilayer capacitor sintered body is barrel-polished, an external electrode paste containing Cu as a main component is electrically connected to the internal electrode end exposed on the end face of the sintered body. After being applied to the end face of the sintered body, the mixture is treated in an atmosphere where the oxygen concentration is controlled by a mixed green gas of nitrogen and hydrogen.
Baking was performed at a temperature of 50 ° 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 a frequency of 1 KHz, dielectric loss tangent (tan δ), capacitance temperature change rate (change rate of capacitance with respect to capacitance of 20 ° C in a temperature range of -55 to + 25 ° C) DC voltage at room temperature The insulation resistance (IR) when 25 V was applied was measured, and the results are shown in (Table 2). Further, as the initial characteristics, the variation of the capacitance, as a standing test, was based on the capacitance (C) when the multilayer capacitor was kept in a thermostat at 150 ° C. for 1 hour, returned to room temperature and left for 48 hours, and then left at room temperature for 1000 hours. Change with time of capacitance (ΔC) with capacitance after time (ΔC /
C), and as an accelerated life test, D at 125 ° C.
Table 3 shows how the insulation resistance was measured after continuously applying a voltage of 200 V for 250 hours. still,
(Table 2), sample No. of (Table 3). Is common to (Table 1), and the same numbers indicate samples having the same composition.

[0020]

[Table 2]

[0021]

[Table 3]

As is clear from (Table 2) and (Table 3),
Dielectric ceramic composition of the present invention (Sample Nos. 3, 4, 6, 9)
~ 12,15 ~ 18,21 ~ 24,28 ~ 31) are dielectric
The rate is as high as 2300 or more, and the variation in capacitance is ± 5% or less.
And the temperature change rate of the capacitance is as small as ± 15% or less.
The insulation resistance is also 1 × 10¹²Above and high. Also leave
The capacitance change with time in the test was -1.0 to -1.3%.
Small and no sub-component phase is generated inside the sintered body.
I understood. On the other hand, the Ba / Ti ratio is 1.001.
Small (sample Nos. 1 and 2) in a reducing atmosphere
The firing reduces the dielectric and turns it into a semiconductor.
If the / Ti ratio exceeds 1.04 (Sample No. 5)
Sintering becomes insufficient and a good sintered body cannot be obtained. Mg
When the added amount of O is less than 0.5 mol (Sample No. 7)
If sintering becomes insufficient, and if it exceeds 5 moles (sample No.
8) The capacitance temperature change rate of the multilayer capacitor has increased.
And the rate of change of the capacitance with time increases.
Not good. Dy_TwoO_ThreeIs less than 0.1 mol
(Sample No. 13) When the rate of change in capacitance with temperature increased,
In particular, the rate of change of capacitance with time and tan δ increase,
On the contrary, if it exceeds 3 moles (sample No. 14)
The dielectric constant drops below 2000, making it impractical. Mn
O_TwoIs less than 0.01 mol (sample N
o. 19) Initial capacitance of the sintered body partially converted into a semiconductor
The variation in the amount is large, the insulation resistance value is small,
As a result, the insulation resistance value deteriorates significantly in the accelerated life test.
Resulting in. If the amount exceeds 0.4 mol (sample N
o. 20) Large rate of change of capacitance and temperature over time
And the deterioration of the insulation resistance also increases. BaO ・ MgO
・ SiO _TwoWhen the amount of the compound added is less than 0.6 mol,
(Sample Nos. 25 and 26) Sintered bodies fired in large quantities are sufficient
Unable to obtain sintering density, variation in capacitance and insulation resistance
Occurs. On the other hand, if the addition amount exceeds 5.0 mol (sample N
o. 27) Although the sinterability is improved, the dielectric constant is reduced,
The rate of change in capacitance with temperature also increases, which is not practical.

From the above results, the main component of BaTiO ₃ 10
BaCO ₃ has a Ba / Ti ratio of 0.001 to 0 mol.
By adding excessively so as to be 0.04 or less, a good sintered body can be obtained without reduction of the dielectric during mass firing in a reducing atmosphere. By 0.5 to 5.0 mol per mol of MgO as to reduce the temperature change of the dielectric constant, has the effect of improving the insulation resistance value, Dy ₂ O ₃
Of 0.1 to 3.0 mol has an effect of improving the temperature change rate of the capacitance and the insulation resistance value. M
By adding 0.01 to 0.4 mol of nO ₂ , reduction of TiO _{2 in} BaTiO _{3 as a} main component can be prevented and insulation resistance characteristics can be improved. It becomes clear that adding 0.6 to 5.0 moles of the BaO.MgO.SiO ₂ compound enables sintering at a relatively low temperature and has the effect of reducing variations in capacitance and insulation resistance. . However, when the addition amount of each additive is out of the range of the present invention, the dielectric ceramic composition becomes a semiconductor at the time of firing, the variation in electric characteristics increases, the capacitance temperature change rate increases, and it is not preferable. You can see that. In this embodiment, BaTiO ₃ and BaO.MgO.SiO ₂ compounds are used as fine powders prepared in advance by a solid phase method. However, similar effects can be obtained by using compounds prepared by a method other than the solid phase method. Has been confirmed.

(Embodiment 2) First, BaTiO ₃ 10
0.02 mol of BaO and 2.5 mol of MgO with respect to 0 mol.
Mol, Dy ₂ O ₃ 1.0 mol, MnO ₂ 0.2 mol,
The composition obtained by adding 2.1 mol of the BaO.MgO.SiO ₂ compound was further added with the amounts of Al ₂ O ₃ and V ₂ O ₅ shown in (Table 4).
Was weighed and added.

[0025]

[Table 4]

Next, after a dielectric ceramic material was manufactured under the same conditions as in the first embodiment, a multilayer capacitor was manufactured using this material. In addition, the amount of green chips packed per sheath during firing was set to 15,000 pieces, which is 1.5 times that of the first embodiment, and the other conditions were the same.
The test was performed in the range of 280 ° C.

Thereafter, the obtained multilayer capacitor was evaluated in the same manner as in the first embodiment, and the results are shown in (Table 5) and (Table 6). In Tables 4 to 6, the same sample No. was used. Indicates a sample having the same composition. Those marked with * are out of the scope of the present invention but are shown for comparison.

[0028]

[Table 5]

[0029]

[Table 6]

As shown in Tables 5 and 6, 0.02 mol of BaO, 2.5 mol of MgO, 1.0 mol of Dy ₂ O ₃ , 100 mol of BaTiO _{3 of} the present invention, Mn
O ₂ 0.2 moles, in a BaO · MgO · SiO ₂ compound 2.1 mol per mol of the composition, further added the dielectric ceramic composition of _{V 2 O 5, Al 2 O} 3, the V ₂ O ₅ 0 .01 to 0.26
Moles (0.02-0.52 moles per 100 moles of BaTiO ₃ as V atoms) (Sample No. 3)
Nos. ₂ to 34, 37, 38) suppress the reduction of TiO ₂ , which is mainly composed of V ₂ O ₅ when the sheath filling amount is increased at the time of firing, and have a high insulation resistance even at a low temperature firing of 1220 to 1280 ° C. An excellent multilayer capacitor without deterioration of the insulation resistance can be obtained. On the other hand, the added amount of V ₂ O ₅ is 0.26 mol (the added amount of V atoms is 0.52 mol)
(Sample No. 36), the temperature change rate of the capacitance becomes large, and the deterioration of the insulation resistance becomes large. Variation in resistance increases. On the other hand, as shown in (Table 6), a composition in which Al ₂ O ₃ was added in an amount of 0.1 to 3.0 mol (0.2 to 6.0 mol as Al atoms) (samples 32 to 34, 37, and 38) Acts on the sub-components to promote sintering, so that a uniform sintered body having no sub-component phase can be obtained. On the other hand, when the addition amount exceeds 3 mol (Sample No. 40), the rate of change in capacity with temperature and tan δ increase, and when the addition amount is less than 0.1 mol (Sample No. 39), a sub-component phase is generated and uniform. It can be seen that a good sintered body cannot be obtained, which is not preferable.

From the above results, it is found that the main component is BaTiO ₃ of the present invention, and BaO, MgO, Dy ₂ O ₃ , MnO _3
2 , by adding a vanadium atom as V ₂ O ₅ to the composition to which BaO · MgO · SiO ₂ is added, in firing in a reducing atmosphere, preventing reduction of the dielectric and improving insulation resistance performance, In addition, aluminum atoms are replaced with Al ₂ O ₃
It is evident that by adding as a component, a uniform sintered body can be obtained by suppressing the generation of a subcomponent phase which is likely to be generated inside the sintered body, and a multilayer capacitor having excellent performance can be obtained.

[0032]

According to the present invention as described above, with respect to BaTiO _3, BaO or _{BaCO 3, MgO, Dy 2 O} 3,
By adding a predetermined amount of MnO ₂ and further a BaO.MgO.SiO ₂ compound, a dielectric ceramic composition for a multilayer capacitor having excellent electric characteristics can be obtained even when firing at a relatively low temperature in a reducing atmosphere. Also, even when a base metal is used as the internal electrode material, the dielectric can be integrally fired. Further, by adding Al atoms and V atoms, it is possible to promote sintering in mass production in a neutral or reducing atmosphere to obtain a uniform sintered body and prevent the dielectric from being reduced. Variations in insulation resistance and capacitance are small, and the capacitance temperature change rate is excellent.

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Yasuo Watanabe 1006 Kazuma Kadoma, Kadoma City, Osaka Prefecture Matsushita Electric Industrial Co., Ltd. (72) Keiji Kobayashi 1006 Kadoma Kadoma, Kadoma City Osaka Prefecture Matsushita Electric Industrial Co., Ltd. F Terms (reference) 4G031 AA03 AA06 AA07 AA11 AA13 AA19 AA29 AA30 BA09 GA02 5E001 AB03 AC09 AE00 AE02 AE03 AE04 AF00 AF06 AH01 AH05 AH06 AH09 AJ01 AJ02

Claims (3)

[Claims] 1. A method according to claim 1, wherein 100 moles of BaTiO ₃ and BaO ₃
Alternatively, BaCO ₃ may be converted to a Ba / Ti ratio of 1.001 to
1.04, and further added MgO to 0.5 to
5.0 mol of Dy ₂ O ₃ 0.1 to 3.0 moles, MnO ₂
The 0.01 to 0.4 mol, the dielectric ceramic composition, characterized in that 0.6 to 5.0 mol per mol of BaO · MgO · SiO ₂ compound. 2. An aluminum atom is converted to Al ₂ O ₃ ,
The dielectric ceramic composition according to claim 1, characterized in that to 0.1 to 3.0 mol added to BaTiO ₃ 100 moles. 3. Conversion of vanadium atom to V ₂ O ₅ ,
_3. The dielectric ceramic composition according to claim 1, wherein 0.01 to 0.26 mol is added to 100 mol of TiO3.