JPH0234553A - Dielectric porcelain composition - Google Patents

Abstract

PURPOSE:To obtain the title compsn. consisting of an Sr-Ca-Nb-O type basic component and a B-Si-Ba-, Mg-, etc.,-O type additive component within a specified range in a specified triangular diagram, capable of being sintered at a relatively low temp. and having a relatively high dielectric constant and high linearity of temp. characteristics of the dielectric constant. CONSTITUTION:A dielectric porcelain compsn. is composed of 100 pts.wt. basic component represented by the formula (where 0.005<=x<=1.995 and 0.7<=k<=1.2) and 0.2-10.0 pts.wt. additive component consisting of B2O3, SiO2 and MO (M is one or more among Ba, Mg, Zn, etc.). The additive component is within the range defined by six straight lines successively connecting points A, B, C, D, E, F in the triangular diagram. Since the dielectric porcelain compsn. is sintered at <=1,200 deg.C in a nonoxidizing atmosphere, it is suitable for use as the dielectric of a laminated porcelain capacitor for temp. compensation fitted with an internal electrode of a base metal such as Ni.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a dielectric ceramic composition suitable as a dielectric of a multilayer ceramic capacitor whose internal electrodes are made of a base metal such as nickel.

[Prior Art] Conventionally, when manufacturing multilayer ceramic capacitors, a conductive paste of noble metal such as platinum or palladium is printed in a desired pattern on a green sheet (unsintered ceramic sheet) made of dielectric ceramic raw material powder. A plurality of these sheets were stacked and pressed together, and sintered in an oxidizing atmosphere at 1300 to 1600°C. Thereby, the dielectric ceramic and the internal electrode can be obtained at the same time. As mentioned above, if a noble metal is used, the intended internal electrode can be obtained even if it is sintered at high temperature in an oxidizing atmosphere. However, since precious metals such as platinum and palladium are expensive, the cost of multilayer ceramic capacitors has inevitably increased.

In order to solve this kind of problem, the use of a ceramic composition consisting of Ca Z r O 3 and M n O 2 as a dielectric material of a capacitor has been proposed, for example, in JP-A-53-9809.
It is disclosed in Publication No. 9. Since the dielectric ceramic composition disclosed herein can be fired in a reducing atmosphere,
Oxidation of base metals such as nickel does not occur.

[Problems to be Solved by the Invention] By the way, the above-mentioned dielectric ceramic composition composed of Ca Z r O 3 and M n O 2 is
For this reason, if a conductive paste containing nickel as a main component is printed on a green sheet and fired, even if the firing is done in a non-oxidizing atmosphere, the nickel particles will melt. Agglomeration occurs and nickel is distributed in beads. Further, due to high temperature firing, nickel diffuses into the dielectric ceramic, causing insulation deterioration of the dielectric ceramic. As a result, it has been difficult to obtain a ceramic capacitor with desired capacitance and insulation resistance.

In order to solve the above problems, the applicant has
No. 2-131415 (Japanese Patent Application No. 60-270540) discloses (Cab) -(Zr (1,).

Tix) Basic components consisting of o2, L120 and 5102
and MO (however, MO is BaOlMgO, Zno, SrO
and at least one kind of CaO), and discloses a dielectric ceramic composition containing an additive component consisting of at least one of CaO and
In Publication No. 1412 (Japanese Patent Application No. 60-270541) {S
Discloses a dielectric ceramic composition comprising a basic component consisting of rO) -1ZTi 10 and additive components consisting of Br(1-x) x 2 2 , 810□ and MO;
In the publication (Japanese Patent Application No. 60-270542) {SrO)
H(Zr <1-x> Tt l Ok
Discloses a dielectric ceramic composition containing a basic component consisting of
In Publication No. 4 (Japanese Patent Application No. 60-270543) (Cab)
, LZr<1-x>Ttx)o2, and additive components consisting of B2O, SlO□, and MO. The dielectric ceramic composition disclosed herein can be used in a reducing atmosphere, 120
It can be obtained by firing under conditions of 0°C or lower. However, when the temperature coefficient of the relative permittivity is around 09 tll, the relative permittivity is a little low at about 35.

In addition, the present applicant has disclosed in Japanese Patent Application Laid-Open No. 62-222514 that 1-x mole part (where X is a numerical value in the range of 0.2 to 0.7 )
of Ca T i O3 and X molar parts of Ca T i S
105, L120, 5102 and M
The present invention discloses a dielectric ceramic composition containing an additive component consisting of at least two of O (where MO is at least one metal oxide of BaO1Mg01ZnO1SrO and CaO).

The dielectric ceramic composition disclosed herein can be obtained by firing in a reducing atmosphere at 10°C or lower, has a relative permittivity of 65 or more, and a capacitance temperature change rate ΔC of -6.21.
% to +6.25%. However, the linearity of the temperature characteristics of capacitance is not sufficient.

Therefore, the object of the present invention is to provide a dielectric ceramic composition that can be obtained by firing in a non-oxidizing atmosphere at a temperature of 1200°C or less, exhibits a relatively high dielectric constant, and has good linearity in the temperature characteristics of the dielectric constant. Our goal is to provide the following.

[Means for Solving the Problems] The present invention for achieving the above object consists of 100 parts by weight of a basic component and 0.2 to 10.0 parts by weight of an additional component, and the basic component is ( S r (2-xCaOl
・Nb 20s (However, X is 0.00) 5≦X≦1.995 for x2. (in the range of 0.7≦≦1.2), and the additive components are B2O3, SiO□ and M
In the triangular diagram showing the composition with O (however, MO is BaO1Mg01ZnO1SrO and at least one metal oxide inside CaO), the B203 is 1 mol%, the S I
Point (A) where O2 is 80 mol% and the MO is 19 mol%
, the B 203 is 1 mol%, and the S l 02 is 3
9 mo/l/%, a point (B) where the MO is 60 mol%, and a point (C) where the B 20 s is 30 mol%, the SiO2 is 0 mol%, and the MO is 70 mol%. Said B2O3
is 90 mol%, the S i O2 is 0 mol%, the M.O.
is 10 mol% (D>, and the point where B2O3 is 90 mol%
, the point (E) where the 5102 is 10 mol% and the MO is 0 mol%, and the point (E) where the BO is 20 mol% and the S10□ is 8
This relates to a dielectric ceramic composition that is within a region surrounded by six straight lines sequentially connecting the point (F) where MO is 0 mol %.

[Operations and Effects of the Invention] The dielectric ceramic composition of the invention described above is produced in a non-oxidizing atmosphere of 120
Since it can be obtained by firing at temperatures below 0°C, it is suitable as a dielectric for temperature-compensating multilayer ceramic capacitors whose internal electrodes are made of base metals such as nickel.

In addition, the relative permittivity is relatively large at 45 to 54 when the temperature coefficient TC is around 0 ppl/''C, and the linearity of the temperature characteristic of the relative permittivity is excellent, and the temperature coefficient TC is +350 to -310 DEI
It is possible to provide a dielectric ceramic composition having a Q of 2000 or more and a resistivity ρ of 1×107 MΩ·1 or more at ll/”ClI MHz.

[Example] Next, the present invention will be explained in detail.

Purity 99 to obtain the basic components of Sample No. 1 in Table 1
% or more of 5rCO3 (strontium carbonate), CaC0
(calcium carbonate) and Nb2O5 (niobium oxide) as starting materials, and without adding impurities to the grain, S r
338.71g (1.2 mol parts) of CO3, CaC
153.09g (0.8 mole part) of O3, Nb2O5
Weighed out 508.20g (1.0 mol parts) and mixed them for 15 hours.Next, the above raw material mixture was mixed for 150 hours.
After drying at ℃ for 4 hours, it was crushed and calcined for 2 hours at an atmospheric width of about 1050℃ to produce {Sr1.2CaO) ・Nb2
O5 powder was obtained.

0.8 2 1.0 On the other hand, in order to obtain the additional components of sample group 1, 8203
0.93g 5i02 64.48g BaC01, 09g MgO1,03g ZnO2,07g 5rCO11,29g CaC05,10g was weighed, 300cc of alcohol was added thereto, and after stirring for 10 hours using an alumina ball in a polyethylene pot, air Temporarily baked at 1000℃ for 2 hours, then baked for 3
It was placed in an alumina pot with 00 cc of water, crushed with an alumina ball for 15 hours, and then dried at 150°C for 4 hours to obtain 1 mol% of B2O3, 80 mol% of S102, and 19 mol% of MO (BaO 5.7 mol%, IV[
A powder of additive components having a composition of 1.9 mol % gO, 1.9 mol % ZnO, 5 7 mol % SrO, and 3.8 mol % CaO was obtained.

Add 30g (3 parts by weight) of the above additive ingredients to 1000g (100 parts by weight) of the above basic ingredients, and then add an organic binder consisting of an aqueous solution of acrylic acid ester polymer glycerin phosphate to the basic ingredients and additive ingredients. 1 to 2% by weight based on the total weight of the powder and 50% by weight of water were further added, and these were placed in a ball mill and pulverized and mixed to prepare a slurry of porcelain raw material.

Next, the above slurry is put into a vacuum deaerator to defoam, and this slurry is put into a reverse roll coater, which is used to form a thin film based on the slurry on a polyester film, and this thin film is applied onto the film. It was heated to 100° C. and dried to obtain a green sheet with a thickness of about 25 μm. This sheet is long and is used by punching out a square with 10x11 sides.

On the other hand, the conductive paste for internal electrodes has an average particle size of 1.5 μm.
10g of nickel powder and 0.9g of ethyl cellulose
was dissolved in 9.1 g of butylcarpitol and placed in a stirrer and stirred for 10 hours. This conductive paste was printed on one side of the green sheet through a screen having 50 patterns each having a length of 14M and a width of 711LI11, and then dried.

Next, place two green sheets with the printed side facing up.
At this time, the adjacent upper and lower sheets were arranged so that their printed surfaces were shifted by about a hand in the longitudinal direction of the pattern. Furthermore, four green sheets each having a thickness of 60 μm were laminated on both the top and bottom surfaces of this laminate.6 Next, this laminate was crimped by applying approximately 40 tons of pressure in the thickness direction at a temperature of approximately 50°C. . Thereafter, this laminate was cut into a grid shape to obtain 100 laminate chips.

Next, this laminate chip was placed in a furnace capable of firing in an atmosphere, and the temperature was raised to 600° C. at a rate of 100° C./h in an air atmosphere to burn the organic binder. Thereafter, the atmosphere in the furnace was changed from air to a reducing atmosphere of H22 volume % + N2 98 volume %. Then, while maintaining the reducing atmosphere in the furnace as described above, the heating temperature of the stacked chips was increased to 600°C.
The temperature was raised at a rate of 100°C/h to the sintering temperature of 1180°C.
The temperature is lowered to 600°C at a rate of 0°C/h, the atmosphere is replaced with an air atmosphere (oxidizing atmosphere), 600°C is maintained for 30 minutes to perform oxidation treatment, and then the sintered chip is cooled to room temperature. was created.

Next, a conductive paste consisting of zinc, glass frit, and vehicle is applied to the side surface of the sintered chip where the electrodes are exposed, dried, and baked in the air at a temperature of 550°C for 15 minutes to form a zinc electrode layer. Copper is deposited on top of this by electroless plating, and then P is deposited on top of this by electroplating.
A b-3n solder layer was provided to form a pair of external electrodes.

As a result, as shown in FIG. 1, the dielectric ceramic layers 1.2.
A multilayer ceramic capacitor 10 was obtained, which consisted of a capacitor 3, an internal electrode 4.5, and an external electrode 6.7.

Note that the thickness of the dielectric ceramic layer 2 of this capacitor 10 is 0.
．． 02mm, the opposing area of internal electrode 4.5 is 5mm x 5w
=25mrr? It is. Moreover, the porcelain layer after firing 1.2.
The composition of No. 3 is substantially the same as the mixed composition of the basic component and the additive component before sintering, and the basic component Sr Ca O-
BOI mol%, SiO2 80 mol%, and Ba between crystal grains consisting of Nb2o5
O3, 7 mol%, MgO 1,95 mol% and ZnO 1,9
A uniform distribution of the additive components consisting of 5.5 mol %, SrO 5.7 mol % and CaO 3.8 mol % is obtained. In addition, MO19 mol% of sample amount 1 is BaOlMgO, Zn
This corresponds to 5.7 mol%, 1.9 mol%, 1.9 mol%, 5.7 mol%, and 3.8 mol% of o, 5rO1CaO, respectively.

Next, the dielectric constant ε5 of the completed [/IF ceramic capacitor,
When we measured the temperature coefficient of dielectric constant TC, Q, and resistivity ρ, as shown in sample No. i in Table 2, C9 was 45, T
C was +20Ell)l/"C1Q was 3400, and ρ was 2.OX107MΩ・I.

Note that the above electrical characteristics were measured in the following manner.

(A) The relative permittivity ε is at a temperature of 25°C and a frequency of IMH.
z, AC voltage (effective value) 0. The capacitance is measured under the condition of
It was calculated from 5 m♂ and the thickness of the porcelain layer 2, 0°05 mff1.

(B) Temperature coefficient of dielectric constant TC (9111/”C)
is the capacitance at 85°C (Cl15) and the capacitance at 25°C (
C25) was measured and calculated using the following formula.

[(C-C)/(C25X60)]XIO(ppH/”
C) (C) Q is the frequency IMHz at a temperature of 25°C,
Measurement was performed using a Q meter at an AC voltage (effective value) of 0.5V.

(D) Resistivity p<MΩ・all) is calculated based on the measured value and dimensions by measuring the resistance value between the pair of external electrodes 6.7 after applying DC 50V for 1 minute at a temperature of 20°C. I asked for it.

The preparation method of sample No. 011 and its characteristics have been described above, but the compositions of the basic components and additive components, their ratios, and the reducing atmosphere (non-oxidizing atmosphere) were also explained for the other samples Nos. 2 to 58. By changing the firing temperature as shown in Tables 1 and 2, a multilayer ceramic capacitor was prepared using the same method as in 1, and the electrical characteristics were measured using the same method.

Table 1 shows the basic components of each sample {Sr(2-x)
Cax02)k ・Nb2O, and the additive components are shown in Table 2. Table 2 shows the firing temperature for sintering each sample in a reducing atmosphere and the electrical characteristics. In the column, the composition formula (S r (2-
x) Cax02 ) (' The values of X and k of Nb2O5 are shown. The amount of added components is 100% of the basic component.
Parts by weight are given in parts by weight. In addition, in the column of MO content in the additive components of Table 1, BaO1Mg01
The proportion of ZnO1SrO1CaO is shown in mol%.

As is clear from Tables 1 and 2, in the samples according to the present invention, when fired in a non-oxidizing atmosphere at 1200°C or less, the relative permittivity ε was 34 to 62, and the temperature coefficient TC of the relative permittivity was +3.
50 to -310 (ppn/'C), Q was 2000 or more, and resistivity ρ was 1×10 7 MΩ·1 or more. Furthermore, as is clear from FIG. 2, which shows the temperature characteristics of the dielectric constant of sample No. 1, sufficient linearity can be obtained. Although only the sample NQI according to the present invention is shown in FIG. 2, the linearity of the relative dielectric constant temperature characteristic of all the samples according to the present invention is excellent. You can get a capacitor.

On the other hand, sample NQ11.12.13.14.15.23.
28.29.34.35.40.41.46.47.5
0.51.54.55.58 cannot achieve the purpose of the present invention, and therefore they are outside the scope of the present invention.

Next, the reasons for limiting the composition will be described.

If the amount of added component is zero, sample No. 23.2
As is clear from 9.35.41, the firing temperature is 1250℃
Although a dense sintered body cannot be obtained even if the distance between samples is 24.
As shown in 30.36.42, when the amount added is 0.2 parts by weight per 100 parts by weight of the basic components, a sintered body having desired electrical properties can be obtained by firing at 1180°C. Therefore, the lower limit of the additive component is 0.2 parts by weight. On the other hand, as shown in 28.34.40.46 between samples, when the amount added is 12 parts by weight, Q becomes less than 2000, which is worse than the desired characteristics, but as shown in 27.33.39.45 between samples. When the amount added is 10 parts by weight, desired characteristics can be obtained. Therefore, the upper limit of the amount added is 10 parts by weight.

If the value of k is 0.6, as shown in Sample Interval 47.51.55, ρ will be less than 1 x 107 MΩ, which will be worse than the desired characteristics, but as shown in Sample Interval 48.52.56. , k is 0.7, desired characteristics can be obtained. Therefore, the lower limit of k is 0.7. On the other hand, between samples 5
As shown in 0.54.58, when the value of k is 1.3, a dense sintered body cannot be obtained, but between the samples, 49.53.57
As shown in FIG. 2, desired characteristics can be obtained when the value of k is 1.2. Therefore, the upper limit of the value of k is 1.2.

The preferred composition of the additive components is 8203S i 0 in Figure 3.
It can be determined based on a triangular diagram showing the composition ratio of 2M O. The first point (A) in the triangular diagram is sample No.
17) B203 is 1 mol%, SiO2 is 80 mol%,
The second point (B) shows the composition of sample NO12 with 19 mol% of MO, 1 mol% of B2O3, 39 mol% of SiO2, and 60 mol% of MO, and the third point (B) shows the composition of sample NO12 with 19 mol% of MO. C)
indicates a composition of sample layer 3 with 30 mol% B2O3, 0 mol% S t O2, and 70 mol% MO, and the fourth point (
D> indicates a composition of sample layer 4 with 90 mol% of B O, 0 mol% of SiO2, and 10 mol% of MO, and the fifth point (
E), B2O3 in sample layer 5 is 90 mol%, SIO
2 is 10 mol%, MO is 0 mol%, and the sixth point (F) is sample NQ6 with 20 mol% B2O3 and Si
The composition is 80 mol% O2 and 0 mol% MO.

The composition of the additive components of the sample that falls within the scope of the present invention is within the region surrounded by six straight lines connecting points 1 to 6 (A) to (F) in the triangular diagram in order. If the composition is within this range, desired electrical characteristics can be obtained. On the other hand, if the composition of the additive components falls outside the range specified in the present invention, as in Samples Nos. 11 to 15, a dense sintered body cannot be obtained.

The MO acid component may be one of BaOlMgO, ZnO1SrO1CaO, as shown in samples No. 16 to 20, or may be in an appropriate ratio as shown in other samples.

[Modifications] Although the embodiments of the present invention have been described above, the present invention is not limited thereto, and, for example, the following modifications are possible.

(a> A trace amount of M n O2 (preferably 0.05-0.
A mineralizing agent such as 1% by weight) may be added to improve the sinterability, and other substances may be added as necessary.

(b) The starting materials may be oxides or hydroxides or other compounds other than those shown in the examples.

(C) The oxidation temperature may be set to a temperature lower than the sintering temperature other than 600°C (preferably in the range of 500°C to 1000°C), that is, various changes may be made in consideration of the oxidation of the electrode such as nickel and the porcelain. Is possible.

(d) The firing temperature in a non-oxidizing atmosphere can be varied depending on the electrode material. When nickel is used as the internal electrode, almost no melt aggregation occurs in the range of 1050°C to 1200°C.

(e) Sintering may be performed in a neutral atmosphere.

(f) It is of course applicable to general ceramic capacitors other than laminated ceramic capacitors.

[Brief explanation of the drawing]

Figure 1 is a sectional view showing a multilayer ceramic capacitor according to an embodiment of the present invention, Figure 2 is a diagram showing the relationship between temperature and dielectric constant of the ceramic capacitor, and Figure 3 is a triangle showing the composition range of additive components. It is a diagram. 1.2.3...Porcelain layer, 4.5...Internal electrode, 6.
7...External electrode.

Claims (1)

[Scope of Claims] Consisting of 100 parts by weight of a basic component and 0.2 to 10.0 parts by weight of additional components, the basic component being {Sr_(_2_-_x_)Ca_xO_2}_k・N
b_2O_5 (however, x is 0.005≦x≦1.995,
k is a numerical value in the range of 0.7≦k≦1.2), and the additive components are B_2O_3, SiO_2, and MO (however, MO is a metal oxide of at least one of BaO, MgO, ZnO, SrO, and CaO). A point (A) in the triangular diagram showing the composition of B_2O_3, 80 mol%, and 19 mol% of B_2O_3, and 19 mol% of MO, respectively, and B_2
The point (B) where O_3 is 1 mol%, the SiO_2 is 39 mol%, and the MO is 60 mol%, and the B_2O_3 is 3
0 mol%, the SiO_2 is 0 mol%, the MO is 70
Point (C) of mol% and the above B_2O_3 is 90 mol%,
Point (D) where the SiO_2 is 0 mol% and the MO is 10 mol%, and the point (D) where the B_2O_3 is 90 mol% and the SiO
A point (E) where _2 is 10 mol% and the MO is 0 mol%,
The B_2O_3 is 20 mol%, and the SiO_2 is 80 mol%.
mol%, and the dielectric ceramic composition is within a region surrounded by six straight lines sequentially connecting the point (F) where MO is 0 mol%.