JP2000109361A - Dielectric porcelain composition and laminated ceramic capacitor using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a dielectric porcelain composition to be used for a laminated ceramic capacitor for temperature compensation, by which stable electric properties can be obtained even when it is fired under a non-oxidative atmosphere. SOLUTION: In a three-component composition expressed by formula, x(MgmCa1-m)O-y(TinZr1-n)O2-zLa2O3 (x+y+z=1), wherein x, y, m, n represent molar ratio, the composition but, m is in the range of 0.3-0.70 and n is in the range of 0.70-0.90} within the region surrounded by the points of a(x=0.49, y=0.50, z=0.01), b(x=0.25, y=0.50, z=0.25) and c(x=0.97, y=0.02, z=0.01) is added with at least one selected from the group of BaSiO3, MgSiO3 and CaSiO3 as an additive in amount of 0.05-3.00 wt.% and further, V2O5 in amount of 0.05-0.03 wt.%, based on 100 wt.% of the composition.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a dielectric ceramic composition for use in a multilayer ceramic capacitor for temperature compensation in which an internal electrode is formed of a base metal such as nickel, and a multilayer ceramic capacitor using the same.

[0002]

2. Description of the Related Art A conventional multilayer ceramic capacitor is obtained by forming a green laminate in which a plurality of ceramic green sheets mainly composed of dielectric powder and internal electrode layers are alternately laminated in accordance with a known method of manufacturing a multilayer ceramic capacitor. After deciding into a predetermined green chip shape, baking is performed at a predetermined temperature, and an external electrode is formed on the end surface of the sintered body so as to be electrically connected to the internal electrode exposed on the end surface of the obtained sintered body. The way to do it is generally done.

However, in recent years, the method of sintering a green chip using a base metal such as nickel for an internal electrode in a non-oxidizing atmosphere has become the mainstream with the increase in the capacity and the lamination of the multilayer ceramic capacitor. .

[0004]

The reason why the conventional multilayer ceramic capacitor is fired in a non-oxidizing atmosphere is to prevent oxidation of internal electrodes of a base metal such as nickel. However, among the multilayer ceramic capacitors, the dielectric ceramic composition used for the multilayer ceramic capacitor for temperature compensation generally has a composition in which rare earth oxides are added to the main components MgTiO ₃ and CaTiO ₃ , and this material is non-oxidized. When sintering is performed in a neutral atmosphere, titanium oxide in the main component is easily reduced, the semiconductor is converted into a semiconductor, insulation resistance is reduced, and desired dielectric characteristics cannot be obtained.

[0005] It is an object of the present invention to provide a dielectric porcelain composition capable of obtaining stable electric characteristics even when fired in a non-oxidizing atmosphere.

[0006]

The present invention for achieving the above object, according to an aspect of, as a general _{formula, x (Mg m Ca 1-} m) O-y
_{(Ti n Zr 1-n)} O 2 -zLa 2 O 3 ( where x + y + z =
In the ternary composition represented by 1), a (x = 0.4
9, y = 0.50, z = 0.01), b (x = 0.2
5, y = 0.50, z = 0.25), c (x = 0.9
7, y = 0.02, z = 0.01) (where m is 0.30 ≦ m ≦ 0.70, n is 0.70 ≦ n ≦
0.90 range) 100 wt%, B as an additive
a selected from the group consisting of aSiO ₃ , MgSiO ₃ and CaSiO ₃ is 0.05 to 3.00 wt%, and V ₂ O ₅ is 0.1 wt%.
The composition is a composition in which the composition is added in the range of 0.5 to 0.30 wt%.

With this configuration, stable electric characteristics can be obtained even when firing in a non-oxidizing atmosphere.

[0008]

DETAILED DESCRIPTION OF THE INVENTION According to a first aspect of the present invention, as a general _{formula, x (Mg m Ca 1-} m) O-y (Ti n
In a ternary composition represented by Zr _{1 -n} ) O ₂ -zLa ₂ O ₃ , a (x = 0.49, y = 0.50, z = 0.0
1), b (x = 0.25, y = 0.50, z = 0.2
5), c (x = 0.97, y = 0.02, z = 0.0)
1) (where m is 0.30 ≦ m ≦ 0.7)
0 and n are in the range of 0.70 ≦ n ≦ 0.90) 100 wt%
On the other hand, BaSiO ₃ , MgSiO ₃ , Ca
One selected from the group of SiO ₃ is 0.05 to 3.00 w
t%, a further dielectric ceramic composition obtained by adding 0.05～0.30Wt% of V ₂ O _5. The general formula is x (Mg _m C
_{a 1-m) O-y} ( represented by _{Ti n Zr 1-n) O} 2 -zLa 2 O 3, yet a (x = 0.49, y = 0.50, z = 0.
01), b (x = 0.25, y = 0.50, z = 0.2
5), c (x = 0.97, y = 0.02, z = 0.0)
The ternary material composition of the present invention surrounded by 1) is composed of MgO,
The sum (x + z) of the molar ratios of CaO and La ₂ O ₃ is always Ti
The composition range is defined so as to be equal to or greater than the sum (y) of the molar ratios of O ₂ and ZrO ₂ . By the V ₂ O ₅ added 0.05～0.30Wt% in this composition, non in an oxidizing atmosphere even if the firing V ₂ O ₅ TiO
₍₂₎ A sintered body having a high insulation resistance and a small capacity temperature coefficient according to the design value is obtained by preventing the reduction of ₂ and therefore a dielectric material of a multilayer ceramic capacitor for temperature compensation using a base metal such as nickel for the internal electrode. And a portion of TiO ₂ that is easily reduced is converted to ZrO ₂
Can further improve the reduction resistance. On the other hand, by adding one selected from the group consisting of BaSiO ₃ , MgSiO ₃ , and CaSiO ₃ by 0.05 to 0.30% by weight, As a sintering aid, promotes sinterability and Q
_{E. An} excellent sintered body having high insulation resistance can be obtained.

According to a second aspect of the present invention, there is provided the dielectric ceramic composition according to the first aspect, wherein the main component x (Mg _m C
In _{a 1-m) O-y} (Ti n Zr 1-n) O 2 -zLa 2 O 3 ( where x + y + z = 1) ternary composition represented by, a
(X = 0.49, y = 0.50, z = 0.01), b
(X = 0.25, y = 0.50, z = 0.25), c
(X = 0.97, y = 0.02, z = 0.01) (where m is 0.30 ≦ m ≦ 0.70, n is 0.70 ≦ n ≦ 0.90) Range) 100 wt%,
Further, Al ₂ O ₃ is 2.0 wt% or less, and MnO ₂ is 0.1 wt%.
This is a dielectric porcelain composition to which 5 wt% or less (except when both are simultaneously 0) is added (where x, y, m, and n represent molar ratios). For the above composition, Al ₂ O ₃ and MnO ₂
Sinterability is further improved by adding
O ₂ has the effect of preventing the reduction of TiO ₂ and increasing the insulation resistance.

According to a third aspect of the present invention, there is provided a multilayer ceramic capacitor comprising a ceramic layer comprising the dielectric ceramic composition according to the first or second aspect and an internal electrode of a base metal such as nickel. is there. A multilayer ceramic capacitor using a base metal such as nickel for an internal electrode is fired in a non-oxidizing atmosphere by forming a ceramic layer with the reduction-resistant dielectric ceramic composition according to claim 1 or 2. This makes it possible to obtain an excellent multilayer ceramic capacitor for temperature compensation which has both a high Q _E and a high insulation resistance and a small capacitance temperature coefficient.

[0011] (Embodiment 1) First, high purity of MgO as starting _{materials, CaO, TiO 2, ZrO 2} , La 2 O 3,
V ₂ O ₅ and BaSiO ₃ powders were weighed so as to have the composition ratios shown in (Table 1) to (Table 5), wet-mixed, dehydrated and dried, and the obtained mixed material was converted to high-purity alumina. It is put in a crucible and calcined in air at a temperature of 1150 ° C. for 2 hours.

[0012]

[Table 1]

[0013]

[Table 2]

[0014]

[Table 3]

[0015]

[Table 4]

[0016]

[Table 5]

Next, the calcined material was put together with pure water and zirconia balls in a rubber-lined ball mill, wet-pulverized, dehydrated and dried to prepare a temperature-compensating dielectric material.
An organic binder was added to the obtained dielectric material for temperature compensation, and after granulation, a disk having a diameter of 15 mm and a thickness of 0.4 mm was formed using a hydraulic press at a forming pressure of 1 ton / cm ² .

Next, the formed disk is placed in an alumina sheath, degreased in air at 700 ° C. for 2 hours, and then heated in a non-oxidizing atmosphere at a temperature shown in (Table 6) to (Table 10). After firing for a time, a sintered body was obtained.

After applying a copper electrode paste to both surfaces of the obtained sintered body and baking it at 900 ° C. in a non-oxidizing atmosphere, the dielectric constant, Q _E , insulation resistance and capacitance temperature coefficient were measured. The results are shown in (Table 6) to (Table 10). The dielectric constant and Q _E were measured at a temperature of 20 ° C., a measurement temperature of 1.0 V _rms , and a measurement frequency of 1 MHz. The insulation resistance was obtained from the resistance value after applying DC 50 V between the electrodes for 1 minute.
The capacitance temperature coefficient was determined by measuring the capacitance at 20 ° C. and 125 ° C. (Equation 1).

[0020]

[Table 6]

[0021]

[Table 7]

[0022]

[Table 8]

[0023]

[Table 9]

[0024]

[Table 10]

[0025]

(Equation 1)

As shown in Tables 6 to 10, in Samples 2, 4, 18, 22, 23, and 26, TiO ₂ was partially reduced and the insulation resistance was extremely reduced. 14,1
Sample No. 9 has insufficient sintering at a temperature of 1350 ° C., so that both Q _E and insulation resistance are reduced. Further, the sample 15 has a large capacitance temperature coefficient of plus 351 ppm / ° C. On the other hand, samples 1, 3,
6, 9, 11, 12, 13, 16, 17, 20, 21,
Within the composition range of the present invention 24 and 25, a large Q _E, higher insulation resistance, it becomes apparent that further temperature coefficient of capacitance is small excellent dielectric characteristics.

The reasons for limiting the respective composition ranges will be described below. First, the reason for limiting the ranges of x, y, and z of the main components will be described. As shown in Samples 2 and 4 in Table 1, the sum of the molar ratios of MgO, CaO, and La ₂ O ₃ (x
+ Z), the range in which the sum (y) of the molar ratios of TiO ₂ and ZrO ₂ is larger, that is, the composition where y> 0.50, when fired in a non-reducing atmosphere, reduces the main component TiO _{2 and} lowers the insulation resistance. In addition, stable dielectric properties cannot be obtained, which is not practical.
Further, as in Sample 8, a composition having a molar ratio (y) of TiO ₂ and ZrO ₂ of 0.01 has insufficient sintering when fired at 1350 ° C., resulting in low Q _E and low insulation resistance. Therefore, the range of y needs to be 0.02 ≦ y ≦ 0.50.

Further, when the value twice the number of moles of z is equal to or larger than the number of moles of y as in samples 5, 7, and 8, sintering is insufficient or sintering becomes difficult, and Q _E , It can be seen that the insulation resistance decreases. That is, in the relationship between y (Ti, Zr) O ₂ and zLa ₂ O ₃ , the number of moles z of La ₂ O ₃ is 2
Since the sintering becomes difficult when the number of times becomes larger than the number of moles y of (Ti, Zr) O ₂ , it is necessary to satisfy y ≧ 2z.
However, the range of y is set to 0.02 ≦ y ≦ 0.50. Therefore, when the value of y changes in the range of 0.02 to 0.50, the value of z always satisfies y ≧ 2z and is 0.01 to 0.25.
In the range. Also, from the relation x + y + z = 1, the range of x is inevitably determined from the values of y and z,
The range of x, y, z of the main component of the present invention is represented by points a,
b and c are limited to the range of the molar ratio enclosed by a straight line.

Next, the reason for limiting the range of the molar ratio m of Mg is as shown in (Table 2) and (Table 7) that the value of m is smaller than 0.30 or larger than 0.70. 1
For 0,14, sintering was insufficient even at 1350 ° C.
Both Q _E and insulation resistance are reduced, making them impractical. Therefore, the range of m needs to be limited to 0.30 ≦ m ≦ 0.70.

The reason for limiting the range of the molar ratio n of Ti is that, as in Sample 15 shown in (Table 3) and (Table 8), n
Is 0.60, the temperature coefficient of capacitance becomes extremely large in the positive direction, which is not practical as a temperature compensating dielectric material, and the value of n is 1.00, ie, T
In the case of 100% of iO ₂ , firing in a non-oxidizing atmosphere
O ₂ is reduced, the insulation resistance is reduced, and stable dielectric properties cannot be obtained. Therefore, the value of n is 0.70 ≦
It is necessary to limit the range to n ≦ 0.90.

On the other hand, the reason for limiting the amount of BaSiO ₃ to be added is that the composition having no added amount such as Sample 19 shown in (Table 4) and (Table 9) is sintered even at 1350 ° C. Insufficiently reduces both Q _E and insulation resistance.
When the addition amount exceeds 3.0 as in Sample 22, the firing temperature is lowered, but a part of the added Si component of BaSiO ₃ enters the Ti position, and the substituted Ti is reduced to Q _E. And lower the insulation resistance. Therefore, BaSi
It is necessary to limit the addition range of O _{3 to} the range of 0.2 to 3.0 wt%.

Further, the reason for limiting the amount of V ₂ O ₅ added is as follows.
(Table 5), the composition amount added is zero as in Sample 23 shown in Table 10 can not protect the reduction of TiO ₂ of the main component, TiO ₂ is in the firing in a non-oxidizing atmosphere As a result, the insulation resistance is reduced and stable dielectric properties cannot be obtained. Also, as in Sample 26, the addition amount was 0.3 wt.
%, It is not preferable because TiO ₂ is reduced and Q _E and insulation resistance are reduced. The reason for this is not clear, but it is considered that V ₂ O ₅ controls the valence of TiO ₂ to make it semiconductor. Therefore, the added amount of V ₂ O ₅ is 0.05 to
It is necessary to limit the range to 0.3 wt%.

(Embodiment 2) Sample 12 of Embodiment 1
MgSiO ₃ or CaS in place of BaSiO ₃
After weighing iO ₃ so as to have the composition ratio shown in (Table 11), the subsequent steps were processed under the same conditions as in Embodiment 1, and the prepared samples were evaluated in the same manner as in Embodiment 1 and the results were evaluated. The results are shown in (Table 12).

[0034]

[Table 11]

[0035]

[Table 12]

As shown in Table 12, Samples 27 to 29 to which MgSiO ₃ was added instead of BaSiO ₃ or Samples 31 to 33 to which CaSiO ₃ was added were BaSiO _3.
As in the case of the addition, it can be seen that excellent dielectric characteristics with high Q _E and high insulation resistance and a small capacitance temperature coefficient can be obtained. When MgSiO ₃ is added, Ba
The insulation resistance is higher than the addition of SiO ₃ , and CaSiO ₃
The addition of it can be seen that the larger the dielectric ceramic composition of Q _E than compared to the addition of BaSiO ₃ is obtained. However, in any case, when the addition amount exceeds 3 wt%, although the effect of lowering the firing temperature is obtained, it is not preferable because the insulation resistance is reduced similarly to BaSiO ₃ .

(Embodiment 3) Sample 12 of Embodiment 1
In addition, Al ₂ O ₃ and MnO ₂ were further weighed to the composition shown in (Table 13), and the subsequent process conditions were processed under the same conditions as in Embodiment 1 to prepare a sample. The results were evaluated in the same manner as in Example 1, and the results are shown in (Table 14).

[0038]

[Table 13]

[0039]

[Table 14]

As shown in (Table 14), the Al of the present invention_Two
O_ThreeAnd MnO_Two35-38 and 40,4
1,43 is Q_E, The insulation resistance is higher, and
Excellent dielectric characteristics with small capacitance temperature
I understand. On the other hand, Al _TwoO_Three2.0 wt.
% Has an effect of lowering the sintering temperature.
Q of thing_EAnd MnO_Two0.5wt
% Of the sample 42 is more than 8 μm
Is not preferred in practice. Therefore, Al_TwoO_ThreeAnd M
nO_Two2.0wt%, 0.5wt% or less respectively
(However, it is necessary to limit both to 0 at the same time)
You can see that

(Embodiment 4) Sample 1 of the dielectric ceramic composition of the present invention produced in Embodiments 1 to 3
A vehicle made of butyl acetate, polyvinyl butyral, and a plasticizer was added to each of the dielectric powders 2, 28, 32, and 43, and a 30-μm-thick ceramic green sheet was prepared by a known doctor blade method.

Next, using the obtained ceramic green sheets of the respective compositions, according to a known method of manufacturing a laminated ceramic capacitor, a green laminate in which 15 internal electrodes and ceramic green sheets were alternately laminated was 600 kg / kg.
After pressure-compression bonding with a pressure of cm ^2, the resultant was cut into a green chip shape of a 1608 type multilayer ceramic capacitor. Note that a nickel electrode paste was used for the internal electrodes.

Next, the green chip was placed in the air for 35 minutes.
After degreasing at a temperature of 0 ° C. for 2 hours, 13 g in a non-oxidizing atmosphere
The firing was performed at 50 ° C. for 2 hours.

Thereafter, external electrodes were provided on the end faces of the obtained sintered body where the internal electrodes were exposed, thereby completing a multilayer ceramic capacitor.

The capacitance, Q _E , temperature coefficient of capacitance, and insulation resistance of each of the obtained multilayer ceramic capacitors were calculated as follows:
The measurement was performed in the same manner as in the first embodiment. Further, as a life test, a DC voltage of 50 V was continuously applied between external electrodes of the multilayer ceramic capacitor for 1000 hours in a thermostat at 125 ° C., and the results are shown in (Table 15).

[0046]

[Table 15]

As is clear from Table 15, the multilayer ceramic capacitors manufactured using the dielectric compositions 12, 28, 32, and 43 within the scope of the present invention have high Q _E and high insulation resistance, and have been subjected to a life test. No deterioration of the characteristics was observed, but samples 19 and 42 of the dielectric powder outside the scope of the present invention were used.
The multilayer ceramic capacitor produced in Example 2 had a low insulation resistance, and the characteristics were also deteriorated in a life test.
In addition, the characteristic deterioration is that the insulation resistance value after the test is 1 × 10
Those which fell to ¹⁰ (Ω) or less were counted as defective.

The above dielectric ceramic composition of the present invention is to prepare a green chip multilayer ceramic capacitor using a non-metal such as nickel internal electrodes, even when the baking it in a non-oxidizing atmosphere, Q _E It is apparent that an excellent multilayer ceramic capacitor for temperature compensation can be obtained which has both a high insulation resistance and a small rate of change in capacitance with temperature and does not cause deterioration in characteristics even in a life test.

In the first to third embodiments, the dielectric material
MgO, CaO, TiO for fabrication_Two, ZrO_Two, La_TwoO_Three,
BaSiO_Three, MgOSiO_Three, CaSiO_Three, V_TwoO_Five,
Al _TwoO_Three, MnO_TwoWas used, but Mg-Ca-
Ti-Zr-O compound or Mg, Ca, Ti, Z
r, La carbonates, hydroxides, etc. are used in the composition of the present invention.
After calcining the main component in advance,
Even if additives are added, characteristics similar to those of the embodiment can be obtained.
Can be.

[0050]

As shown in the above results, according to the present invention, the dielectric ceramic composition of the present invention is also Q _E and insulation resistance are both high and fired in a non-oxidizing atmosphere, yet excellent small temperature coefficient of capacitance A sintered body having dielectric properties is obtained, and can be used as a dielectric material for a multilayer ceramic capacitor using a base metal such as nickel for the internal electrodes. In particular, since it has excellent _QE characteristics and a small capacitance temperature coefficient, it is highly practical as a multilayer ceramic capacitor material for temperature compensation used in high-frequency circuits and the like.

[Brief description of the drawings]

FIG. 1 is a three-component diagram showing a composition range of a dielectric ceramic according to the present invention.

Continued on front page F-term (reference) 4G031 AA03 AA04 AA06 AA09 AA11 AA12 AA13 AA19 AA29 AA30 AA39 BA09 CA03 5E001 AB03 AC09 AE00 AE03 AE04 AF06 AH01 AH05 AH08 AH09 AJ01 AJ02

Claims (3)

[Claims] 1. The general formula x (Mg_mCa_1-m) O-
y (Ti_nZr_1-n) O _Two-ZLa_TwoO_Three(However, x + y + z
= 1) in the ternary composition represented by a (x = 0.
49, y = 0.50, z = 0.01), b (x = 0.2
5, y = 0.50, z = 0.25), c (x = 0.9
7, y = 0.02, z = 0.01)
M is 0.30 ≦ m ≦ 0.70, n is 0.70 ≦ n ≦
0.90 range) 100 wt%, B as an additive
aSiO_Three, MgSiO_Three, CaSiO_ThreeFrom the group of
The other one is 0.05 to 3.00 wt%, and V_TwoO_FiveTo 0.
The dielectric porcelain composition added with 0.5 to 0.30 wt% (note that
x, y, m, and n represent molar ratios). 2. A main component _{x (Mg m Ca 1-m} ) of the dielectric ceramic composition according to claim _{1 O-y (Ti n Zr} 1-n) O 2 -
In a ternary composition represented by zLa ₂ O ₃ (where x + y + z = 1), a (x = 0.49, y = 0.50, z =
0.01), b (x = 0.25, y = 0.50, z =
0.25), c (x = 0.97, y = 0.02, z =
0.01) (where m is 0.30 ≦ m ≦
0.70, n is in the range of 0.70 ≦ n ≦ 0.90) 100
The dielectric porcelain composition (x, y, and y) containing 2.0 wt% or less of Al ₂ O ₃ and 0.5 wt% or less of MnO ₂ (except when both are 0 at the same time).
m and n represent a molar ratio). 3. A multilayer ceramic capacitor comprising a ceramic layer made of the dielectric ceramic composition according to claim 1 and an internal electrode of a base metal such as nickel.