JPH0323258A - Dielectric porcelain composition - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] Industrial Field of Application The present invention has a high dielectric constant, insulation resistance, dielectric breakdown voltage (high dielectric breakdown voltage), greatly improves the degree of goodness q, has a small temperature coefficient of capacitance, and is a multilayer ceramic capacitor. The present invention relates to a dielectric ceramic composition that can prevent a decrease in capacitance and quality Q when the thickness of the internal electrode is made thinner, and can reduce fluctuations in capacitance and quality Q. .

Conventional technology Conventionally, the dielectric constant and insulation resistance are high, and the QK quality is excellent.
The following systems are known as dielectric ceramic compositions with small capacitance temperature coefficients.

・BaO - Tie2- Nd20, system - BaO-
Tie2-Sm20, Problems to be Solved by the Tie2-Sm20 System Invention However, these compositions, for example, O. Q9 BaO
-0.5 6 TiO - 0.3 5 840,2
Based on the composition ratio, we used a dielectric material with a palladium internal electrode thickness of 4 μm and a dielectric thickness of 12 μm. Internal electrode overlap dimension 1.2
m x 0. 7 111;g, When a multilayer Sewamic capacitor having a laminated structure with 19 dielectric layers is manufactured, the average value of capacitance is 742pF. Average value of quality Q: 287
00, average value of capacitance temperature coefficient: N36ppm/”C
, average value of insulation resistance: 6.0 x 10''Ω, average value of dielectric breakdown strength: 117 k▼/W, which are not satisfactory values in terms of insulation resistance.

1. Since the crystal grain size is as large as 1 to δμl, the porosity in the element body becomes large, and the electric field strength applied to each crystal grain becomes too large, and the dielectric breakdown strength is also not a satisfactory value.

Furthermore, in order to reduce the cost of the 8F-layer semicondenser, and to prevent the occurrence of decomposition, which is a structural defect inside the button and the element body, the thickness of the internal electrode of the 8F layer was reduced from 4 μl to 2 μm, and the above composition ratio was reduced. The average value of capacitance of a multilayer ceramic capacitor using a dielectric material of The bowing becomes large at 266-7139F. Furthermore, there was a problem in that the average value of the quality level Q was as low as 4,000, and the fluctuation of the quality level Q was large, ranging from 600 to 8,800.

Means for Solving the Problems In order to solve these problems, the present invention uses the general formula x BaO y [ (TiO z ) ( + −
m > (ZrO 2 )m] -S (R●
− Me) When expressed as O (however, (+n)
nS/2! +7+Z=1.00, 0.001≦m≦0.200,
0.01≦n≦0.20, Re is La, Pr,
One or more rare earth elements selected from Ha, am, M
e is one or more rare earth elements selected from rare earth elements excluding Lm, Pr, Na, and 316; ), x, y, z
Nb205, 'ra20,, Y205 as subcomponents to 100 parts by weight of the main component consisting of the molar ratio range surrounded by the points a, b, c, d, e, f'' shown below.
Two or more types selected from ``= 0.001 to 0.0 in total
The present invention proposes a dielectric ceramic composition characterized by containing 10 mole parts.

FIG. 1 is a ternary diagram showing the composition range of the main components of the composition according to the present invention, and the reason for limiting the composition range of the main components will be explained with reference to FIG. That is, sintering is extremely difficult in the ▲ region. Furthermore, in region B, the quality Q is low 1, making it impractical. Furthermore, in the C and D regions, the capacitance mm degree coefficient becomes too large on the negative side, making it impractical.

In region E, the temperature coefficient of capacitance shifts toward the buoys direction, but the dielectric constant is too small to be practical. 1, R
By selecting e from La, Pr, N(1, Sm), it is possible to shift the capacitance temperature coefficient in the positive direction without lowering the dielectric constant in the order of La, Pr, Nd, and Sm. Adashi, L+a, Pr, Nd
, Sm or a combination thereof, it is possible to adjust the capacitance temperature coefficient. Furthermore, La, Pr,
The effect of significantly improving the quality Q by replacing a part of one or more rare earth elements selected from Nd and Sm with one or more rare earth elements selected from rare earth elements other than La, Pr, Nd, and Sm. If the amount of substitution is less than 0.01, there is no effect of substitution; if it exceeds 0.20, the dielectric constant decreases and becomes impractical.

In addition, by replacing Tie2 with ZrO2, the effect of reducing the crystal grain size and increasing the dielectric breakdown strength can be achieved without significantly changing the dielectric constant, goodness Q, capacitance temperature coefficient, and insulation resistance values. and its substitution rate m is 0.001
If it is less than 0.200, there will be no substitution effect, and if it exceeds 0.200, the dielectric constant, quality Q, and insulation resistance will decrease.

FIG. 2 &-6 shows the main components of the composition according to the present invention.
Figure 7 shows the effect of the inclusion of subcomponents Nb205, Ta205, and V205 on the characteristics of multilayer ceramic capacitors.
Adashi, Nb205, 'ra20,, V205y)
The reason for limiting the content range a will be explained with reference to the graph.

Fig. 2 K fj U1cNb205, Ta205, V20
By containing 5 V, the insulation resistance and dielectric breakdown strength are improved, the capacitance and quality Q of the case are increased, and the dispersion of the capacitance and quality Q is reduced.

Sosite, Nb 20 s r Ta 20 5 1 V
205, the insulation resistance and dielectric breakdown strength are improved, but Nt)205,? The total content of a205 and V20 is 0.001 parts by weight per 100 parts by weight of the main component.
If it is less than a molar part, the capacitance and goodness factor Q are low, and the variation in capacitance and goodness factor Q is large, so it is excluded from the scope of this invention.

On the other hand, Nb205, τa2o,, v2o5 (7) containing vt
If the total exceeds 0.010 mole parts based on the main components, the quality Q and insulation resistance will decrease, and the temperature coefficient of capacitance will become large on the negative side, making it impractical. 1, N
By containing two or more selected from b205, Ta205, V205, Nb205, Ta2
05, v20, etc., the dielectric constant, insulation resistance, and dielectric breakdown voltage are higher, the quality Q is excellent, and the capacitance temperature coefficient can be reduced.

Example The present invention will be explained below using specific examples.

(Example 1) Chemically high purity BaCO3, TiO■ are used as starting materials.
, ZrO■, La20, , Pr60, , ,
Nd20, , Sm203, Coo. ,G(120
, *”320s, Wb20,, TIL205
'h=J: HiV205 powder was weighed to have the composition ratio shown in Table 1 below, put into a rubber-lined ball mill equipped with agate balls together with pure water, wet mixed, and then dehydrated and dried. This dry powder was placed in a high alumina crucible and calcined in air at 1100°C for 2 hours. This calcined powder was placed together with pure water in a rubber-lined ball mill equipped with agate balls, wet-pulverized, and then dehydrated and dried. After adding an organic binder to this pulverized powder and making it homogeneous,
The particles are sized through a mesh sieve and molded using a mold and hydraulic press at a molding pressure of 1 ton/aI1, with a diameter of 15 m and a thickness of 0.
．． Molded to 4vax.

Next, the formed disk was placed in an alumina pod covered with zirconia powder, and heated in air at the temperature shown in Table 1 below.
Firing was performed for a period of time to obtain dielectric porcelain having the composition ratio shown in Table 1.

(Left below) ? The thickness and diameter of the dielectric porcelain disk obtained as described above were measured, and the samples for measuring the dielectric constant, goodness Q, and capacitance temperature coefficient were prepared by placing silver electrodes on both sides of the dielectric porcelain disk. A sample for baking, insulation resistance, and dielectric breakdown strength measurements was prepared by providing a 1-strip width area on the inner side of the outer periphery of a dielectric ceramic disk, and baking a silver electrode thereon. The dielectric constant, goodness Q, and electrostatic sensitivity temperature coefficient were determined using YHP's digital LCR meter model 4276▲ at a measurement temperature of 20°C, a measurement voltage of 1, Vrrns, and a measurement frequency of 1MHz. Ta. Among them, the capacitance temperature coefficient is 20℃ and 86℃
The capacitance was measured and calculated using the following formula.

TO = (G − Go) /Co X1 /e 5
X1 06TC: Capacitance temperature coefficient (ppm, /'c
) Co: Capacitance at 20° C. (pF) C: Capacitance at 86° C. (pF) The dielectric constant was determined using the following formula.

K = 1 43.8 YHP HR meter model #
43 2 9 ▲, and the measurement voltage was 5 0 V. D,C
,, the measurement time was 1 minute.

The dielectric breakdown strength was determined by using a high-voltage power supply PH835K-3 manufactured by Kikusui Electronics Co., Ltd., placing the sample in silicone oil, and dividing the dielectric breakdown voltage determined by a voltage increase rate of 50 V/sea by the dielectric thickness. The dielectric breakdown strength per 1 fl was defined as the dielectric breakdown strength. The crystal grain size was determined by optical microscopic observation at a magnification of 400.

The test results are shown in Table 2 below.

(Left below) (Example 2) Chemically highly purified BaCO3, Tie2 were used as starting materials.
,zrO2lNd203lC602lNb205lTa
205i? and v205 powder, composition ratio 0. o
s BaO0.6 6 TiO -0.3 5 [
For 100 parts by weight of the main component of (NdO3,2)(1,5(Coo2).o5]2, (Nb205)...
4 ('ra205). , (V205). ．． , f o,
o. o o o 1,0.00 1 0, 0.0
A calcined pulverized powder containing 100,0.0200 mol parts is prepared in the same manner as in Example 1. However, (Nb
205)a4(τ'205)[L3(Y205)0
．． 3 content of 0%, 0.0001, 0.0200 parts by weight is outside the scope of this invention, and 0.0 0 1 0, 0.
0 100 mole parts is within the scope of this invention.

An organic binder, a plasticizer, a dispersant, and an organic solvent were added to this calcined and pulverized powder and mixed in a pot equipped with an alumina ball to prepare a slurry. After mixing, the filtered slurry was processed into a green sheet having a dielectric thickness of 12 μm after sintering. 10 sheets of such green sheets were stacked on a support stand, screen printed with internal electrode barodium base (ML-3724 manufactured by Shoei Kagaku Co., Ltd.) so that the internal electrode thickness after sintering would be 2 μm, and dried. did.

One green sheet is laminated on top of this, and the internal electrode overlap dimension after sintering is 1. Internal electrode Baodium paste was printed by shifting the printing position so that it would be 2 m x 0.7 + 1111, and after drying, one green sheet was laminated. These operations were repeated for 1, with the number of dielectric layers being 19. On top of this, 10 green sheets were laminated. After sintering this laminate, the internal electrode overlap dimensions are 1.2m x 0.
．． It was cut into a laminated semi-conductive capacitor having a laminated structure with 7 shoulders and 19 dielectric layers. The cut sample was placed in an alumina pod covered with zirconia powder, and heated from room temperature to 350'C''! at 5°C/hr in air.
Raise the temperature at 360℃ and 100℃/hr,
After firing at 1270°C for 2 hours, the temperature was lowered to room temperature 1 at 100°C/hr. Next, the sample surface after firing is polished,
The part of the internal electrode that will be connected to the external electrode is fully exposed, and a silver external electrode is baked onto the exposed part of the internal electrode to make it conductive with the internal electrode. The capacitance, quality Q, temperature coefficient of capacitance, insulation resistance, and dielectric breakdown strength of these samples were determined by measurements under the same conditions as in Example 1. Also, confirm the laminated structure by pressing the button in the length direction and about 1/2 in the width direction of the multilayer ceramic capacitor.
The polished cross section of the inner electrode is shown at a magnification of 100. The dielectric thickness and the internal electrode thickness were determined by optical microscope observation at a magnification of 400.

The measurement results are shown in Figures 2a-e.

Among them, in the method for producing dielectric ceramic used in the examples, %Ba
CO, , Tie■, Zr02, L&203,
Pr60, ,”20s, Sm20, , Co
o2, G(120, , Dy20, , Wb20
5, Ta20, & v205 were used, but the method is not limited to this method. Compounds such as BaTiO, or carbonates, etc. may be used to obtain the desired composition ratio. BaO, Tie2,
ZrO2, Lm203, Pr60, , , )1
6203, S! D203, Coo2, Gd205,
Dy20, , Wb205, Ta, 05p and v
20, it is possible to obtain properties comparable to those of the examples.

1. Even if the main component is calcined in advance and subcomponents are added, properties comparable to those of the examples can be obtained.

In addition, in the example, La. Pr. Nd. Although Ge, Dy, and Gd have been described as rare earth elements Me other than Sm, characteristics comparable to those of the examples can be obtained even if other rare earth elements are used.

In addition to the basic composition mentioned above, S102, MnO2,
Salts, oxides, etc. that are generally considered fuwaxes, such as Fe20, ZnO, etc., can also be added within a range that does not impair the properties.

Effects of the Invention As described above, according to the present invention, the crystal grain size is small, the dielectric constant, insulation resistance, and dielectric breakdown voltage are high, the quality Q is greatly improved, the capacitance temperature coefficient is small, and the laminated When used in ceramic capacitors, it is possible to prevent a decrease in capacitance and quality Q when the thickness of the internal electrode is made thinner, and to reduce fluctuations in capacitance and quality Q. By making it thinner, the cost of multilayer ceramic capacitors can be reduced, and delamination, which is an internal structural defect, can be prevented from occurring. In addition, since the dielectric breakdown voltage is high, the thickness of the dielectric layer can be made thinner, and the element body can be made smaller and larger in capacity.

[Brief explanation of drawings]

FIG. 1 is a ternary diagram explaining the composition range of the main components of the composition according to the present invention, and FIGS.
0.35[(NdO3/2)0.95(C”2)0.
05] subcomponent (Nb
205). ．． 4 (Ta205). 3 (v205), the effect of containing 3, dielectric thickness: 12 μm, internal electrode overlap dimension: 1.2 wax x O. γ plate, number of dielectric layers: 1
9 is a graph showing the electrical characteristics of a laminated semi-conductive capacitor having a laminated structure of No. 9.

Claims (1)

[Claims] General formula xBaO-y[(TiO_2)_(_1_-_m_)(
ZrO_2)_m]-z(Re_(_1_-_n_)M
e_n) When expressed as O_3_/_2 (however, x+y+
z=1.00, 0.0001≦m≦0.200, 0.0
1≦n≦0.20, Re is one or more rare earth elements selected from La, Pr, Nd, Sm, Me is La, Pr, N
d, one or more rare earth elements selected from rare earth elements excluding Sm. ), x, y, z are the points a, b, c,
Main component 10 consisting of the molar ratio range surrounded by d, e, f
0 parts by weight, Nb_2O_5, Ta_ as subcomponents
A dielectric ceramic composition containing a total of 0.001 to 0.010 parts by mole of two or more selected from 2O_5 and V_2O_5.