JP2531548B2 - Porcelain composition for temperature compensation - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a temperature compensating porcelain composition suitable for a laminated porcelain capacitor having a base metal such as Cu (copper) as an internal electrode.

[0002]

2. Description of the Related Art Conventionally, a noble metal such as Pd (palladium) has been mainly used as an internal electrode of a laminated ceramic capacitor. However, in recent years, in order to reduce the cost of the electrodes, it has been studied to form the internal electrodes with an inexpensive base metal such as Ni. In order to allow the use of base metals, the porcelain composition must sinter below the melting point of the base metal. JIS standard S using Ni (nickel) as internal electrode
For temperature compensating porcelain capacitors such as L characteristics, please refer to
24388, JP-A-62-157604,
JP-A-62-157605 and JP-A-62-157.
606, JP-A-63-157607, JP-A-63-86314, JP-A-63-86315, JP-A-63-86316, and JP-A-63-8.
6317, JP-A-63-86318, JP-A-63-86319 and the like. The dielectric ceramic composition disclosed in the above publication is 1200 ° C.
It can be sintered in the following reducing atmosphere.

[0003]

By the way, in recent years, the frequency of electronic circuits has been remarkably increased, and there is a strong demand for a ceramic capacitor suitable for high frequencies of several 100 MHz to several GHz. However, since Ni has a high resistivity, the resistance value of the Ni electrode inevitably becomes high, and since Ni is a ferromagnetic material, the effective resistance value of the Ni electrode due to the skin effect increases in the high frequency region. As a result, there is a problem that the Q value of the Ni electrode porcelain capacitor is significantly reduced in the high frequency region.

In order to solve the above-mentioned problems, it is conceivable to use Cu (copper), which has a low resistivity, is a non-magnetic material and has excellent high frequency characteristics. However, the melting point of Cu is 1083
Since it is ℃, it is difficult to obtain a porcelain sufficiently densified by the dielectric ceramic composition disclosed in the above publication.

Therefore, an object of the present invention is to provide a dielectric ceramic composition which can be fired in a reducing atmosphere at 1050 ° C. or less and which conforms to JIS standard SL characteristics (+350 to −1000 ppm / ° C.).

[0006]

The present invention for achieving the above object is (1-α-β) {(Sr _1-x Ca _x ) O}.
_k {(Ti _1-y Zr _y ) O ₂ } + αLi ₂ SiO ₃ + β
MF ₂ (However, MF ₂ is CaF ₂ , SrF ₂ , Ba
At least one alkaline earth fluoride selected from F ₂ and MgF ₂ , α is a numerical value in the range of 0.01 to 0.05, β is a numerical value in the range of 0.01 to 0.05, and k is 1. 00-1.
Numerical value in the range of 04, x is a numerical value of 0.35 to 0.50, y
Relates to a temperature-compensating porcelain composition consisting of 0.10 or less).

[0007]

Function: Li ₂ SiO ₃ (lithium silicate) and alkaline earth fluoride MF ₂ (CaF ₂ , SrF ₂ , Ba)
By adding F ₂ and MgF ₂ ), a liquid phase occurs at a low temperature during firing, and a densified porcelain can be obtained by firing at 1050 ° C. or less. In addition, with the above composition, JIS standard SL characteristics can be obtained.

[0008]

EXAMPLES Next, the dielectric ceramic compositions according to the examples and comparative examples of the present invention and temperature compensating ceramic capacitors using the same will be described. (1-α-β) {(Sr _1-x Ca _x ) O} _k {(Ti
35 samples having different compositions were prepared as shown in Tables 1 and 2 in order to obtain 35 kinds of dielectric ceramic compositions according to the composition formula of _1-y Zr _y ) O ₂ } + αLi ₂ SiO ₃ + βMF ₂ . In Table 1, the column of (1-α-β) is the main component in the composition formula {(Sr _1-x Ca _x ) O} _k {(Ti _1-y
The ratio of Zr _y ) O ₂ } is shown by a molar ratio. These values in the composition formula are shown in columns 1-x and x. 1
-X, x show the molar ratio of Sr and Ca. In the columns 1-y, y, these values in the composition formula are shown. In addition,
1-y and y represent the ratios of Ti (titanium) and Zr (zirconium) in the composition formula by the molar ratio. This value in the composition formula is shown in the column of k. Note that k is a value indicating the proportion of {(Sr _1-x Ca _x ) O} _{k in} the main component. The column α in Table 2 shows the ratio of Li ₂ SiO ₃ (lithium silicate), which is the first additive component in the composition formula, in molar ratio. The column of MF ₂ shows the content of the alkaline earth fluoride in the composition formula (MgF ₂ , CaF ₂ , BaF ₂ , Sr.
F ₂ ) and β values thereof (molar ratio to the entire composition) are shown. The β column shows the overall β value of MF ₂ , that is, the β value in the composition formula. Given the values in each column of Table 1 and Table 2, the composition formula related to the present invention can be specified.

[0009]

[Table 1]

[0010]

[Table 2]

Next, a method for manufacturing a dielectric ceramic composition according to sample No. 1 and a ceramic capacitor using the same will be described. The dielectric ceramic composition of sample No. 1 can be expressed by the following formula. 0.94 {(Sr _0.65 Ca _0.35 ) O} _1.01 {(Ti _0.95
Zr _0.05 ) O ₂ } + 0.03Li ₂ SiO ₃ +0.03
CaF ₂ First, the main component of this composition is 0.94 {(Sr _0.65 Ca _0.35 ) O} _1.01 {(Ti _0.95
Zr _0.05 ) O ₂ } to obtain SrCO ₃ having a purity of 99% or more.
(Strontium carbonate), CaCO ₃ (calcium carbonate), TiO ₂ (titanium oxide), and ZrO ₂ (zirconium oxide) were weighed.

Next, the weighed raw materials of the main components were put in a pot mill together with water and zirconia balls, and wet mixed for 15 hours. Next, the slurry obtained by this mixing was put in a stainless steel vat and dried by a hot air dryer at 150 ° C. for 4 hours.
Calcination at ℃ for 2 hours, (1-α-β) {(Sr _1-x Ca _x ) O} _k {(Ti
_A main component according to _1-y Zr _y ) O ₂ } was obtained.

Next, Li ₂ SiO ₃ as the first additional component and CaF as the second additional component having a purity of 99% or more.
₂ and were weighed in such a ratio that α = 0.03 and β = 0.03, and the main component {(Sr _1-x Ca _x ) O} _k {(Ti _1-y Z
r _y ) O _2} powder, put them in a pot mill together with water and zirconia balls, wet mix for 15 hours, put the obtained slurry in a stainless vat and dry with hot air to obtain a dielectric ceramic composition ( A raw material mixture) was obtained.

Next, 3% by weight of polyvinyl alcohol as an organic binder was added to the raw material mixture powder to granulate the mixture, which was put in a mold and pressed by a hydraulic press at a pressure of 2000 kg / cm ² to obtain a disk having a diameter of 10 mm and a thickness of 1 mm. Molded into. Next, this disc (molded body) was subjected to heat treatment (debinding treatment) at 500 ° C. for 5 hours in the atmosphere to burn off the organic binder, and then H ₂ (0.1%) + N ₂ (99. 9%)
Was calcined in a weak reducing atmosphere at 940 ° C. for 2 hours.

Next, I is formed on both sides of the sintered dielectric ceramic disk.
By applying a conductive paste of an n-Ga (indium-gallium) alloy, as shown in FIG.
And a pair of electrodes 2 and 3 was completed.

Next, the relative permittivity ε _s , Q value, temperature coefficient TC of capacitance, and resistivity ρ of the completed ceramic capacitor were measured. Table 3 shows the electrical characteristics and firing temperature of each sample.
The electrical characteristics were measured under the following conditions. (A) The relative permittivity ε _s has a temperature of 25 ° C., a frequency of 1 MHz,
The capacitance of the capacitor was measured under the condition of a voltage (effective value) of 1 V, and calculated from the measurement result, the thickness of the porcelain disc and the electrode area. (B) The Q value was measured under the same conditions as ε _s . (C) The temperature coefficient TC (ppm / ° C.) of the electrostatic capacity was calculated by the following equation by measuring the 25 ° C. capacity C ₂₅ and the 125 ° C. capacity C ₁₂₅ of the capacitor. TC (ppm / ° C.) = {(C ₁₂₅ −C ₂₅ ) / C ₂₅ } ×
{1 / (125-25)} × 10 ⁶ (D) The resistivity ρ (MΩ · cm) is measured by measuring the resistance value after applying 1 kV DC to the capacitor for 1 minute at a temperature of 25 ° C. Based on the calculation.

Sample Nos. 2 to 35 are also the same as Sample No. 1 except that the composition of the dielectric ceramic composition is changed as shown in Tables 1 and 2 and the firing temperature is set to the value shown in Table 3. Dielectric porcelain discs and capacitors were prepared by the method described above, and the electrical characteristics were measured by the same method.

[0018]

[Table 3]

[0019]

[Table 4]

As is clear from Table 3, ε _s of the ceramic capacitor of sample No. 1 is 278, Q is 7600, and TC is −
950 ppm / ° C., ρ is 1.29 × 10 ⁷ .

In the present invention, sintering is possible at 1050 ° C. or lower, ε _s is 200 or higher, and TC is -760 to -99.
0ppm / ℃, Q is 3000 or more, ρ is 1 × 10 ⁷ MΩ
-The goal is a dielectric porcelain composition that can obtain electrical characteristics of cm or more. Many samples meet the desired or desired properties, but sample Nos. 4, 5, 12, 13, 1
Nos. 7, 18, 22, 29, 34, and 35 do not satisfy the desired characteristics, and are comparative examples.

Of the 35 samples, NO. 1 to NO. 5 are Ca
NO. 6 to NO. 12 are for clarifying the proper range of the x value showing the ratio of NO, and NO. 6 to NO. 12 are for clarifying the proper range of the y value showing the ratio of Zr. .1
7 is for clarifying the proper range of the k value indicating the ratio of Ca + Sr to Ti + Zr, and NO. 23-
28 is MgF ₂ , CaF ₂ , BaF ₂ , S as MF _2.
It is intended to clarify that any one or more of rF ₂ can be used, and NO.
Is for clarifying the proper range of β value.

Next, the reasons for limiting the composition of the dielectric ceramic composition according to the present invention will be described. The value of x is sample No. 1, 19
21 to 0.35, desired electrical characteristics can be obtained, but as shown in Sample No. 4, in the case of 0.30, the temperature coefficient TC of the capacity is -1300.
It deteriorates to ppm / ° C. Therefore, the lower limit of the value of x is 0.
35. On the other hand, when the value of x is 0.50 as shown in sample No. 3 and 30 to 33, the desired electrical characteristics can be obtained, but in the case of 0.55 as shown in sample NO. In addition, the temperature coefficient TC of the capacity deteriorates to -1180 ppm / ° C. Therefore, the upper limit of the value of x is 0.50.

The value of y is 0.1 as shown in sample No. 11.
In the case of 0, desired electrical characteristics can be obtained, but in the case of 0.12 as shown in sample No. 12, the temperature coefficient TC of capacity deteriorates to -1350 ppm / ° C. Therefore, the upper limit of the value of y is 0.10. Zr has a function of increasing the Q value and the resistivity ρ, but desired electrical characteristics can be obtained even when the value of y is 0 as shown in Sample No. 6. Therefore, the range of the value of y is 0.10.

The value of k is 1.0 as shown in sample No. 14.
In the case of 0, the desired electrical characteristics can be obtained, but in the case of 0.98 as shown in sample No. 13, Q
Value decreases sharply and the resistivity ρ is also 1 × 10 ⁶ MΩ · cm
Less than Therefore, the lower limit of the value of k is 1.00. On the other hand, the value of k is 1.04 as shown in sample No. 16.
In the case of, the desired electrical characteristics can be obtained, but sample No. 1
As shown in 7, when 1.06, a dense sintered body cannot be obtained even if fired at 1100 ° C. Therefore, the upper limit of the value of k is 1.04.

The value of α indicating the proportion of Li ₂ SiO ₃ is the sample
In the case of 0.01 as shown in NO. 19, desired electrical characteristics can be obtained, but in the case of 0.005 as shown in sample NO. 18, it is dense even if fired at 1100 ° C. No sintered body can be obtained. Therefore, the lower limit of the value of α is 0.0
It is 1. On the other hand, when the value of α is 0.05 as shown in sample NO. 21, desired electrical characteristics can be obtained, but when the value of α is 0.06 as shown in sample NO. Has a temperature coefficient of -1100 ppm / ° C and a specific resistance ρ of 1
It becomes × 10 ⁷ MΩ · cm. Therefore, the upper limit of the value of α is 0.05.

The value of β indicating the ratio of MF ₂ is sample No. 3
In the case of 0.01 as shown in 0 and 31, desired electrical characteristics can be obtained, but in the case of 0.005 as shown in sample No. 29, it is dense even if fired at 1100 ° C. No sintered body can be obtained. Therefore, the lower limit of the value of β is 0.0
It is 1. On the other hand, when the value of β is 0.05 as shown in sample No. 33, desired electrical characteristics can be obtained, but in the case of 0.06 as shown in sample NO. 34 and 35. Has a temperature coefficient TC of capacity of −1100 ppm / ° C. or more and a specific resistance ρ of less than 1 × 10 ⁷ MΩ · cm. Therefore, the upper limit of the value of β is 0.05. In addition, sample No.
As shown in 23 to 28, MgF is a component of MF _2.
2 , CaF ₂ , BaF ₂ , and SrF ₂ work almost the same,
Similar effects can be obtained by using one selected from these or a plurality of selected ones.

In the above-mentioned embodiment, a single layer capacitor having an In--Ga alloy electrode was prepared in order to facilitate the preparation of a ceramic capacitor as a sample. Instead of this, a green sheet of a porcelain composition according to the present invention (not yet prepared) was prepared. C on the sintered porcelain sheet)
The u (copper) paste is applied and dried, and then the laminate is laminated, and the molded body and the electrodes are baked simultaneously in a reducing or non-oxidizing atmosphere at 1050 ° C. or lower, and a plurality of layers are formed as shown in FIG. Cu in the dielectric ceramic layers 1a, 1b, 1c of
It is possible to obtain a temperature compensating laminated ceramic capacitor having a structure in which the internal electrodes 4 and 5 are provided and the external electrodes 6 and 7 connected thereto are provided. Since Cu forming the internal electrodes 4 and 5 has a low resistivity and is a non-magnetic material, a capacitor having excellent high frequency characteristics can be obtained.

In the range that does not impair the object of the present invention,
Trace amount of MnO ₂ (preferably 0.05 to 0.3% by weight)
The sinterability can be further improved by adding a mineralizing agent such as. In addition, {(Sr _1-x Ca _x ) O} _k {(Ti
_As a starting material for producing _1-y Zr _y ) O ₂ }, oxides, hydroxides or other compounds other than those shown in the examples may be used.

[0030]

As is apparent from the above, according to the present invention, it is possible to sinter at 1050 ° C. or lower in a reducing atmosphere, ε _s is 200 or more, and TC is −760 to −990.
ppm / ° C, Q is 3000 or more, ρ is 1 × 10 ⁷ MΩ ・
It is possible to provide a temperature-compensating porcelain capacitor having electrical characteristics of cm or more.

[Brief description of drawings]

FIG. 1 is a sectional view showing a porcelain capacitor according to an embodiment of the present invention.

FIG. 2 is a sectional view showing a laminated ceramic capacitor according to the present invention.

[Explanation of symbols]

 1 Dielectric porcelain disk 2 Electrode 3 Electrode

Claims (1)

(57) [Claims] 1. (1-α-β) {(Sr _1-x Ca _x ).
O} _k {(Ti _1-y Zr _y ) O ₂ } + αLi ₂ SiO ₃
+ ΒMF ₂ (However, MF ₂ is CaF ₂ , SrF ₂ , BaF ₂ , Mg
At least one alkaline earth fluoride of F ₂ , α is a numerical value in the range of 0.01 to 0.05, β is a numerical value in the range of 0.01 to 0.05, and k is 1.00 to 1 A value in the range of 0.04, x is a value of 0.35 to 0.50, and y is a value of 0.10 or less).