JP2000143343A - Dielectric porcelain composition and multilayer ceramic capacitor using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a dielectric porcelain composition capable of providing stable electric characteristics even by baking in a nonoxidizing atmosphere and useful for a multilayer ceramic capacitor for temperature compensation. SOLUTION: This dielectric porcelain composition is obtained by adding 0.05-3.00 wt.% of one selected from the group of BaSiO3, MgSiO3 and CaSiO3 and further 0.05-0.30 wt.% of V2O5 as additives to 100 wt.% of a composition surrounded by (a)[(x)=0.49, (y)=0.50, (z)=0.01], (b)[(x)=0.25r (y)=0.50, (z)=0.25] and (c)[(x)=0.97, (y)=0.02, (z)=0.01] [with the proviso that (m) is within the range of 0.30<=(m)<=0.70; (n) is within the range of 0.70<=(n)<=0.90] in a ternary composition represented by x(MgmCa1-m)O-y(TinZr1-n)O2-zSm2O3 (x), (y), (m) and (n) denote each molar ratio; [(x)+(y)+(z)] is 1} as the formula.

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 monolithic ceramic capacitor is formed by alternately laminating a plurality of ceramic green sheets mainly composed of a dielectric ceramic composition and a plurality of internal electrode layers according to a known method of manufacturing a monolithic ceramic capacitor. After cutting the body into a predetermined green chip shape,
A method of baking at a predetermined temperature and forming an external electrode on the end face of the sintered body so as to be electrically connected to the internal electrode exposed on the end face of the obtained sintered body is generally performed.

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

[0004]

The reason why the conventional multilayer ceramic capacitor is fired in a non-oxidizing atmosphere is to prevent oxidation of a base metal internal electrode 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 main components MgTiO ₃ and CaTiO _3. When fired in a non-oxidizing atmosphere, titanium oxide in the main component is easily reduced, and has a problem that it is converted into a semiconductor and the insulation resistance is reduced, and desired dielectric properties cannot be obtained.

[0005] It is an object of the present invention to provide a dielectric ceramic composition capable of obtaining stable electric characteristics even when fired in a non-oxidizing atmosphere, and a multilayer ceramic capacitor using the same.

[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 -zSm 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%.

[0007] With this configuration, even when firing in a non-oxidizing atmosphere, stable electric characteristics can be obtained.

[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 -zSm 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 0.70 ≦ n ≦ 0.90)
Range) 100 wt%, and BaSiO as an additive
₃ , MgSiO ₃ , CaSiO ₃ , one selected from the group consisting of 0.05 to 3.00 wt%, and V ₂ O ₅ of 0.05 to 3.0 wt%.
It is a dielectric porcelain composition to which 0.30 wt% is added. General _{formula, x (Mg m Ca 1-} m) O-y (Ti n Zr 1-n) O 2
−zSm ₂ O ₃ , and 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), the sum of the molar ratios of MgO, CaO and Sm ₂ O ₃ (x + z) is always equal to the molar ratio of TiO ₂ and ZrO ₂ . The composition range is defined so as to be equal to or larger than the sum (y) of the ratio. V ₂ O ₅ is added to this composition in an amount of 0.05 to 0.
By adding 30 wt%, even if firing is performed in a non-oxidizing atmosphere, V ₂ O ₅ prevents reduction of TiO ₂ , and a sintered body having a large insulation resistance and a small capacity temperature coefficient as designed is obtained. can get. Therefore, it is suitable as a dielectric ceramic composition for a multilayer ceramic capacitor for temperature compensation using a base metal such as nickel for the internal electrodes. Further, by substituting a part of TiO ₂ which is easily reduced with ZrO ₂ , reduction resistance can be further improved. On the other hand, Ba
By adding one selected from the group consisting of SiO ₃ , MgSiO ₃ and CaSiO ₃ in an amount of 0.05 to 3.00 wt%,
These promote sinterability as a sintering aid, and can provide an excellent sintered body having high Q _E and high insulation resistance.

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 -zSm 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 0.5 w%.
The dielectric porcelain composition according to claim 1, wherein t% or less (however, both are simultaneously excluding 0) is added (where x, y, m, and n represent a molar ratio). Sinterability is further improved by adding Al ₂ O ₃ and MnO ₂ to the above composition. In particular, MnO 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 and second aspects and an internal electrode of a base metal such as nickel. is there. By forming the ceramic layer from the reduction-resistant dielectric porcelain composition according to claim 1 or 2, the multilayer ceramic capacitor using a base metal such as nickel for the internal electrode can be fired in a non-oxidizing atmosphere. 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} , Sm 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 crucible made of high-purity alumina. 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 dielectric ceramic composition for temperature compensation. An organic binder was added to the obtained dielectric ceramic composition for temperature compensation, and after granulation, a disc having a diameter of 15 mm and a thickness of 0.4 mm was formed at a molding pressure of 1 ton / cm ² using a hydraulic press.

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 were shown in (Table 6) to (Table 10). The dielectric constant and Q _E were measured at a temperature of 20 ° C., a measurement voltage of 1.0 Vrms, and a measurement frequency of 1 MHz. The insulation resistance was determined 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, the samples
2,4,18,22,23,26 are TiO_TwoIs partially reduced
As a result, the insulation resistance was extremely reduced, and samples 8, 10, 14, 1
9 is 1350 ° C because of insufficient sintering._E, Insulation resistance
Samples 5 and 7 are sintered at a temperature of 1350 ° C.
do not do. Further, the sample 15 has a capacitance temperature coefficient
351 ppm / ° C. On the other hand, samples 1, 3,
6, 9, 11, 12, 13, 16, 17, 20, 21,
24, 25 within the composition range of the present invention _EIs large
High insulation resistance and low capacitance temperature coefficient
It becomes clear that excellent dielectric properties can be obtained.

The reasons for limiting the respective composition ranges will be described below. First, the reason for limiting the range of x, y, and z of the main component will be described. Samples 2 and 4 in Table 1
In the range where the sum (y) of the molar ratios of TiO ₂ and ZrO ₂ is larger than the sum (x + z) of the molar ratios of MgO, CaO and Sm ₂ O ₃ , that is, the composition in which y> 0.50, When fired in a non-reducing atmosphere, TiO _{2 as} the main component is reduced, the insulation resistance is low, and stable dielectric properties cannot be obtained, which is not practical.

As shown in Sample 8, TiO ₂ and ZrO ₂
When the composition (sum) of the molar ratios (y) is 0.01, sintering is insufficient at 1350 ° C., and both Q _E and insulation resistance are reduced. Therefore, the range of y needs to be 0.02 ≦ y ≦ 0.50. In addition, as in Samples 5, 7, and 8, the number of moles of z is 2
It can be seen that when the double value is equal to or larger than the number of moles of y, the sintering is insufficient or difficult, and the Q _E and the insulation resistance decrease. That is, y (Ti, Zr) O ₂ and zSm ₂ O
_In relation to ₃ , twice the number of moles z of Sm ₂ O ₃ is
When the number of moles of (Ti, Zr) O ₂ is larger than y, sintering becomes difficult, so 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 relationship x + y + z = 1, the range of x is inevitably determined by the values of y and z, and the range of x, y, and z of the main component of the present invention is determined by points a, b, and c is 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 that as shown in (Table 2) and (Table 7), the value of m is 0.30
Sample 1 having a composition smaller than or larger than 0.70
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 dielectric ceramic composition for temperature compensation.
0, i.e., if the TiO ₂ 100%, TiO ₂ is reduced by firing in a non-oxidizing atmosphere, the insulation resistance is lowered, not stable dielectric characteristics. Therefore, it is necessary to limit the value of n to the range of 0.70 ≦ n ≦ 0.90.

On the other hand, the reason why the addition amount of BaSiO ₃ was limited was as shown in Table 4 and the composition with no addition amount as in sample 19 shown in Table 9 was 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 why the addition amount of V ₂ O ₅ is limited 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 is 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 thought that V ₂ O ₅ controls the valence of TiO ₂ and turns it into a 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 produced sample was evaluated in the same manner as in Embodiment 1, and the results were obtained. Are shown in (Table 12).

[0035]

[Table 11]

[0036]

[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
Compared to the addition of SiO _3, the insulation resistance is higher and CaSi
It can be seen that the addition of O ₃ results in a dielectric ceramic composition having a higher Q _E than the addition of BaSiO ₃ . 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).

[0039]

[Table 13]

[0040]

[Table 14]

As shown in Table 14, the Al of the present invention_Two
O_ThreeAnd MnO_Two35-38 and 40,4 added with
1,43 is Q_E, The insulation resistance is higher, and
Excellent dielectric characteristics with low capacitance temperature coefficient
You can see that. On the other hand, Al _TwoO_Three2.0w
Sample 39 exceeding t% does not have the effect of lowering the sintering temperature.
Although Q_EAnd MnO_Two0.5
The sintered body of Sample 42 exceeding wt% has an abnormal composition of 8 μm or more.
Long particles are observed, which is not practically preferable. Therefore, Al
_TwoO_Three, And MnO_Two2.0 wt% and 0.5 wt%, respectively.
wt% or less (however, excluding 0 at the same time for both)
It is necessary to understand that it is necessary.

(Embodiment 4) Sample 1 of the dielectric ceramic composition of the present invention produced in Embodiments 1 to 3
A vehicle composed of butyl acetate, polyvinyl butyral, and a plasticizer was added to each of the dielectric powders of 2, 19, 28, 32, 42, and 43, and a thickness of 3 was obtained by a known doctor blade method.
A 0 μm ceramic green sheet was produced.

Next, using the obtained ceramic green sheets of the respective compositions, a green laminate in which 15 internal electrodes and ceramic green sheets were alternately laminated in a thickness of 600 kg / cm ² was prepared according to a known method of manufacturing a multilayer capacitor. After pressure-compression bonding under pressure, a 1608 type multilayer ceramic capacitor was cut into a green chip shape.
Note that a nickel electrode paste was used for the internal electrodes. Next, the green chip was degreased in air at a temperature of 350 ° C. for 2 hours, and then baked at 1350 ° C. in a non-oxidizing atmosphere 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. 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 ceramic compositions 12, 28, 32 and 43 within the scope of the present invention have high Q _E and high insulation resistance, and have a long service life. While no characteristic deterioration was observed in the test, the multilayer ceramic capacitors manufactured by using the dielectric ceramic composition samples 19 and 42 outside the scope of the present invention exhibited lower insulation resistance, and the life deterioration test showed no characteristic deterioration. Admitted. In addition, as for the characteristic deterioration, those whose insulation resistance value after the life test was reduced to 1 × 10 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 base metal such as nickel internal electrodes, even when the baking it in a non-oxidizing atmosphere, Q _E, It is clear that an excellent multilayer ceramic capacitor having both high insulation resistance and a small rate of change in capacitance with temperature and having no characteristic deterioration even in a life test can be obtained.

Further, in the first to third embodiments, the production of the dielectric ceramic composition was performed using MgO, CaO, TiO ₂ , ZrO ₂ , Sm.
₂ O ₃ , BaSiO ₃ , MgSiO ₃ , CaSiO ₃ , V ₂ O
_Although the powder of No. ₅ was used, a compound of Mg—Ca—Ti—Zr—O, or a carbonate, hydroxide or the like of Mg, Ca, Ti, Zr, or Sm may be used so as to have the composition of the present invention. ,
Further, even if the main component is preliminarily calcined and then an additive is added, characteristics similar to those of the embodiment can be obtained.

[0050]

As shown in the above results, the dielectric properties of the present invention
The ceramic porcelain composition has a Q_EAnd absolute
Both edge resistance is high and capacitance temperature coefficient is small.
A sintered body with improved dielectric properties is obtained,
For multilayer ceramic capacitors using base metal for internal electrodes
It can be used as a dielectric ceramic composition. In particular, Q
_EExcellent characteristics and low temperature coefficient of capacitance
Ceramic condenser for temperature compensation used in roads, etc.
It is highly practical as a dielectric ceramic composition.

[Brief description of the drawings]

FIG. 1 is a ternary diagram showing the range of the dielectric ceramic composition of the present invention.

 ────────────────────────────────────────────────── ─── Continued on the front page F term (reference) 4G031 AA03 AA04 AA06 AA07 AA11 AA12 AA13 AA19 AA29 AA30 AA39 BA09 CA03 5E001 AB03 AC09 AE00 AE03 AE04 AF06 AH01 AH05 AH09 AJ01 AJ02

Claims (3)

[Claims] 1. The general formula x (Mg_mCa_1-m) O-
y (Ti_nZr_1-n) O _Two-ZSm_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)
And 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 the ternary composition represented by zSm 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
_2. The dielectric ceramic composition according to claim 1, wherein Al ₂ O ₃ is added in an amount of 2.0 wt% or less and MnO ₂ is added in an amount of 0.5 wt% or less (except when both are 0 at the same time). (Where x, y, m, and n represent molar ratios). 3. A multilayer ceramic capacitor comprising a ceramic layer comprising the dielectric ceramic composition according to claim 1 and an internal electrode of a base metal such as nickel.