JP3450903B2 - Non-reducing dielectric porcelain composition - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a nonporous ceramic capacitor, and more particularly to a non-reducing ceramic capacitor suitable for a laminated ceramic capacitor having internal electrodes mainly composed of a base metal such as nickel or copper. The present invention relates to a dielectric ceramic composition. 2. Description of the Related Art Conventionally, a multilayer ceramic capacitor generally has a structure in which a plurality of dielectric sheets mainly composed of BaTiO ₃ having an internal electrode applied to a surface thereof are laminated, and the internal electrodes of each sheet are alternately arranged in parallel. To a pair of external connection electrodes,
It is formed by sintering and integrating this. Such multilayer ceramic capacitors have been used in a wide variety of electronic circuits, as electronic components have been rapidly reduced in size with the development of electronics in recent years. [0003] However, the conventional laminated ceramic capacitor using a dielectric material containing BaTiO ₃ as a main component as a dielectric is a conventional palladium (palladium) which is an expensive noble metal as an internal electrode. (Melting point: 1555 ° C.) or an alloy thereof, and particularly when the capacitance is large, there is a problem that the number of internal electrodes increases and the cost increases. Therefore, the conventional multilayer capacitor has a high volumetric efficiency, is excellent in dielectric properties, and has high reliability. [0004] On the other hand, in order to solve the disadvantage of the conventional multilayer ceramic capacitor, which is expensive, it has been attempted to use an inexpensive base metal such as nickel as the internal electrode. However, when a base metal such as nickel is used as the internal electrode, barium titanate (BaTiO ₃ )
When simultaneously sintering a dielectric consisting of a base metal and a base metal internal electrode, the condition for sintering the base metal as a metal film without being oxidized is that the equilibrium oxygen partial pressure of Ni / NiO is about 0.03 Pa at 1300 ° C. Therefore, the oxygen partial pressure must be lower than that, and in this case, the dielectric composed of BaTiO ₃ or a solid solution thereof is generally reduced under the above oxygen partial pressure and loses the insulating property. There is a disadvantage that practical dielectric properties as a capacitor cannot be obtained. Therefore, as a porcelain composition which can be used as a laminated ceramic capacitor having an internal electrode of nickel or the like, barium titanate solid solution (Ba, Ca, Sr) Ti
O ₃ is a basic oxide (Ba, Ca, S
r) A non-reducing dielectric porcelain composition containing O in excess of stoichiometric ratio with respect to TiO ₂ as an acidic oxide is disclosed in
No. 42588, for example. Generally, in the ABO ₃ type crystal, the stoichiometric amount of the A ion which takes 12 coordination with oxygen larger than the B ion is larger than the B ion located at the center of the oxygen octahedral (perovskite) structure. If the stoichiometric ratio is excessive, it is known that the crystal lattice strongly attracts oxygen atoms and is hardly reduced, and the invention described in the above publication is based on this stoichiometric deviation, It has improved non-reducing properties. However, the dielectric porcelain composition described in the above-mentioned publication has a value of -55 based on + 25 ° C.
The temperature change rate of the relative dielectric constant at -125 ° C is + 20-
It was as large as 80, and had a drawback that the dielectric properties were deteriorated. According to the present invention, even when baked at 1150.degree. C. to 1350.degree. C., no reduction occurs, and base metal powder particles such as nickel used as an internal electrode are sintered as a metal film without being oxidized. Provided is a highly economical non-reducing dielectric ceramic composition having an excellent dielectric constant, excellent insulating properties, a small rate of temperature change of the dielectric constant over a wide temperature range, a small dielectric loss tangent, and an extremely economical high dielectric constant system. The purpose is to do so. The non-reducing dielectric porcelain composition of the present invention has a composition formula of 10 based on the molar ratio of metal elements.
0 (Ba _1-x Ca _X ) _{1 + k} TiO ₃ + aRE ₂ O ₃ + bMnO
+ CMgO + dLi ₂ O + eSiO ₂ (RE is Y, G
d, Dy, Ho, Er and Yb)
Where a, b, c, d, e, x and k in the formula are 0.25 ≦ a ≦ 2.50, 0.05 ≦ b ≦ 0.50,
0.50 ≦ c ≦ 8.00, 1.50 ≦ d ≦ 4.50,
0.75 ≦ e <2.00, 0 <x ≦ 0.025, 0 ≦ k
<A / 50 is satisfied. Here, the composition formula based on the molar ratio is 100
(Ba _1-x Ca _X ) _{1 + k} TiO ₃ + aRE ₂ O ₃ + bMnO +
When expressed as cMgO + dLi ₂ O + eSiO ₂ , BaTi
The reason why the molar ratio a of the rare earth element oxide RE ₂ O _{3 to} 100 mol of O ₃ is 0.25 ≦ a ≦ 2.50 is that when a is smaller than 0.25, the insulation resistance becomes small,
This is because practical dielectric properties as a laminated ceramic capacitor cannot be obtained, and when a is larger than 2.50, the relative permittivity is reduced, sinterability is reduced, and insulation resistance is reduced. a is 0.50 ≦ a ≦ 1.00. In addition, M per 100 moles of BaTiO ₃
The reason why the molar ratio b of nO is set to 0.05 ≦ b ≦ 0.50 is that when b is smaller than 0.05, the insulation resistance becomes low and the practical dielectric properties as a laminated ceramic capacitor are reduced. If b is larger than 0.50, the aging rate increases, and practical dielectric properties as a laminated ceramic capacitor cannot be obtained. b is 0.10 ≦ b ≦ 0.40, especially 0.10 ≦ b
≤0.20. The reason that the molar ratio c of MgO to 100 mol of BaTiO ₃ is 0.50 ≦ c ≦ 8.00 is that if c is smaller than 0.50, the insulation resistance is reduced. Is larger than 8.00, the relative dielectric constant is low, and the insulation resistance is low. c is 1.00
≤ c ≤ 2.00. In addition, L per 100 mol of BaTiO ₃
The reason why the molar ratio d of i ₂ O is set to 1.50 ≦ d ≦ 4.50 is that when d is smaller than 1.50, the temperature characteristic of the relative dielectric constant becomes poor, and d becomes smaller than 4.50. Is too large, the relative dielectric constant becomes low. d is 1.50 ≦ d ≦ 2.
50. Furthermore, the reason why the molar ratio e of SiO _{2 to} 100 mol of BaTiO ₃ is 0.75 ≦ e <2.00 is that when e is smaller than 0.75, the sinterability deteriorates. This is because dense porcelain cannot be obtained at a firing temperature of 1350 ° C., and when e is 2.00 or more, the relative dielectric constant is low and the insulation resistance is low. e is 0.75 ≦ e ≦ 1.5
0, especially 0.75 ≦ e ≦ 1.00. Then, the substitution amount x of Ba for Ca is 0 <
The reason for setting x ≦ 0.025 is that when x is more than 0.025, the relative dielectric constant decreases and the insulation resistance also decreases. x is 0 <x ≦ 0.010. Further, k in the composition formula is 0 ≦ k <a / 5.
The reason for setting the value to 0 is that when k is smaller than 0, the insulation resistance is reduced, and when k is a / 50 or more, the sinterability is reduced and the densification is not performed. k is 0.010 ≦ k ≦
0.020. In the present invention, BaTi
The average crystal grain size of O ₃ is desirably 1.5 μm or less. This is because the average crystal grain size of BaTiO ₃ is 1.5 μm.
This is because if it is larger than m, the insulation resistance tends to decrease, and the absolute value of the temperature change rate of the dielectric constant tends to increase. That is, in the present invention, the molar ratio of the rare earth element oxide RE ₂ O _{3 to} 100 mol of BaTiO ₃ is 0.5
0 ≦ a ≦ 1.00, 0.10 ≦ b ≦ 0.40, 1.00
≤c≤2.00, 1.50≤d≤2.50, 0.75≤
e ≦ 1.50, 0 <x ≦ 0.010, 0.01 ≦ k ≦
Desirably, it is 0.02. The non-reducing dielectric ceramic composition of the present invention is mixed with, for example, BaCO ₃ powder, TiO ₂ powder and CaCO ₃ powder and then subjected to a solid-phase reaction at a predetermined temperature to obtain (Ba, Ca).
A TiO ₃ powder is synthesized and pulverized to a particle size of 1.5 μm or less. Next, to this synthetic fine powder (Ba, Ca) TiO ₃ powder, MnCO ₃ powder and MgCO ₃ powder, Y ₂ O ₃ , Gd ₂ O ₃ ,
At least one powder selected from Dy ₂ O ₃ , Ho ₂ O ₃ , Er ₂ O ₃ , Yb ₂ O ₃ , Li ₂ CO ₃ powder, and SiO ₂
The powder was added and weighed to a predetermined ratio, and mixed with a dispersant and a dispersion medium in a ball mill to prepare a raw material slurry. An organic binder and a plasticizer were added to the slurry, and after sufficiently stirring, the slurry was formed into a film by a doctor blade method. The films are stacked and cut into a predetermined shape after thermocompression bonding. Then, the molded body is obtained by controlling the oxygen partial pressure to 3 × 10 ^{−5 to} 3 × 10 ⁻³ Pa and firing at 1150 to 1350 ° C. using a nitrogen gas as a carrier gas. According to the present invention, the porcelain does not reduce even when fired at 1150 ° C. to 1350 ° C., and base metal powder particles such as nickel used as internal electrodes are not oxidized and formed into a metal film. It is sintered, has a high relative dielectric constant and excellent insulating properties, has a small temperature change rate of the dielectric constant over a wide temperature range, has a small dielectric loss tangent, and is extremely economical. MnO, MgO, rare earth oxides (Re
_{The addition of 2} O ₃ ) effectively works to improve reduction resistance and reliability. These form acceptor levels,
By adding these, 3 × 10 ^{−5 to} 3 × 10 ⁻³
Donor level electrons formed by oxygen defects generated when firing under a low oxygen partial pressure of Pa are MnO, MgO,
The recombination at the acceptor level formed by adding the rare-earth oxide suppresses the dielectric ceramic from becoming a semiconductor and maintains high insulating properties. The aging characteristics are proportional to the amount of MnO added, and MnO
By limiting the amount, a dielectric ceramic composition with small aging can be obtained. EXAMPLES Reference Example 1 BaCO ₃ powder having a purity of 99% or more as a starting material, Ti
After mixing using O ₂ powder, a solid phase reaction is performed at 1150 ° C.
TiO ₃ was synthesized and pulverized to a particle size of 1.5 μm or less.
Next, this synthetic fine powder BaTiO ₃ and MnCO ₃ powder, Mg
At least one powder selected from Ho ₂ O ₃ , Er ₂ O ₃ , and Yb ₂ O ₃ is added to CO ₃ powder and weighed so as to have a ratio shown in Tables 1 and 2, respectively. The mixture was mixed in a ball mill to prepare a raw material slurry. An organic binder and a plasticizer were added to the slurry, and after sufficiently stirring, the slurry was formed into a film by a doctor blade method. This film is stacked and cut after thermocompression bonding (vertical) 10 mm x (horizontal) 10 mm x (thickness) 0.5 mm
Sample was obtained. This sample was controlled at an oxygen partial pressure of 3 × 10 ⁻⁵ Pa, and the carrier gas was nitrogen at 2250 ° C. at 1250 ° C.
Fired for hours. In the upper and lower surfaces of the finally obtained sintered body, In
An electrode for electrical characteristics was formed by applying a -Ga alloy. [Table 1] [Table 2] Next, after leaving these evaluation samples at room temperature for 48 hours, a frequency of 1.0 kHz and an input signal level of 1.
The capacitance and the dielectric loss tangent were measured at 0 Vrms. The relative permittivity was calculated from the capacitance. Thereafter, a direct current of 50 V was applied for 1 minute, and the insulation resistance at that time was measured. Also,
In the temperature range of −55 to 125 ° C., the capacitance and the dielectric loss tangent were measured under the same conditions as above, and the rate of change of the capacitance at each temperature with respect to the capacitance at + 25 ° C. was calculated. The above results are shown in Tables 3 and 4. However, Table 1
“A”, “b” and “c” in the table indicate the molar ratio with respect to 100 mol of BaTiO ₃ , and the unit is a molar part. The insulation resistance was represented by the product (CR, MΩ · μF) of the capacitance (C, μF) and the insulation resistance (R, MΩ). The unit is MΩ ・ μF
It is. [Table 3] [Table 4] As is clear from Tables 1 to 4, No. 1 in which the addition amount a of the rare earth element oxide is less than 0.25 mol part has a low insulation resistance, and conversely, No. 1 in which the addition amount a exceeds 3 mol parts. 11,
In Nos. 16 and 20, the relative permittivity tends to be low, and the sinterability is reduced, and the insulation resistance is reduced. When the amount c of MgO was less than 1 mole part, In No. 6, the insulation resistance was low, and conversely, No. In No. 21, the relative dielectric constant is low and the insulation resistance is low. When the amount b of MnO exceeds 8 mol parts,
o. 26 and 27, the insulation resistance was low and the (b + c) value was 1
No. exceeding 1.2 mole parts. In 21, 26 and 34, the relative permittivity is low. Each of the samples of Reference Example 1 had a relative dielectric constant of 2
It exhibited excellent characteristics of 500 or more, a dielectric loss tangent (tan δ) of 1.5% or less, an insulation resistance of 1000 MΩ · μF or more, and a temperature change rate of relative permittivity of ± 15% or less. Reference Example 2 BaCO ₃ powder having a purity of 99% or more, Ti
After mixing using O ₂ powder, a solid phase reaction is performed at 1150 ° C.
TiO ₃ was synthesized and pulverized to a particle size of 1.5 μm or less.
Next, this synthetic fine powder BaTiO ₃ and MnCO ₃ powder, Mg
CO ₃ powder _{Y 2 O 3, Gd 2 O} 3, Dy 2 O 3, Ho 2 O 3,
At least one kind of powder selected from Er ₂ O ₃ and Yb ₂ O ₃ was added, and further, Li ₂ CO ₃ powder and SiO ₂ powder were weighed so as to have the ratios shown in Table 5, respectively. The mixture was mixed in a ball mill to prepare a raw material slurry. [Table 5] An organic binder and a plasticizer were added to the slurry, and after sufficient stirring, a film was formed by a doctor blade method. This film is stacked and cut after thermocompression bonding (vertical) 10 mm x (horizontal) 10 mm x (thickness) 0.5 mm
Sample was obtained. This sample was controlled at an oxygen partial pressure of 3 × 10 ⁻⁵ Pa, and the carrier gas was nitrogen at 2250 ° C. at 1250 ° C.
Fired for hours. In the upper and lower surfaces of the finally obtained sintered body, In
An electrode for electrical characteristics was formed by applying a -Ga alloy. Next, the relative dielectric constant, insulation resistance, dielectric loss tangent and the rate of change of the capacitance at each temperature with respect to the capacitance at + 25 ° C. were measured for these evaluation samples in the same manner as in Reference Example 1. After heat treating the evaluation sample at 150 ° C. for 1 hour,
It was left at 25 ° C., and the change rate (aging rate) of the capacitance after 10 hours with respect to the capacitance after 1 hour was calculated. Table 6 shows the results. Here, the insulation resistance was represented by the product (CR, MΩ · μF) of the capacitance (C, μF) and the insulation resistance (R, MΩ). In Table 5, a, b, c, d, and e are B
The molar ratio is shown with respect to 100 moles of aTiO _3, and the unit is a mole part. [Table 6] As is clear from Tables 5 and 6, when the addition amount a of the rare earth oxide Re ₂ O ₃ is less than 0.25 mole part,
In the case of No. 13, the insulation resistance is low. On the contrary, in the case of No. 17 in which a exceeds 2.5 mol parts, the specific permittivity tends to be low, the sinterability is reduced, and the insulation resistance is reduced. In the case of No. 25 to which Sm, which is a rare earth element having a large ionic radius, is added, the dielectric loss is large, the insulation resistance is low, and the temperature characteristics are poor. In the case of No. 7 in which the amount c of MgO is less than 0.5 mol part, the insulation resistance is low, and in the case of No. 12 in which c exceeds 8 mol part, the relative dielectric constant is low. In addition, the insulation resistance is low in No. 1 in which the MnO amount b is less than 0.05 mol part, and the aging rate is large in No. 6 in which b exceeds 0.5 mol part. Li ₂ O
No. 32 in which the amount d is less than 1.50 mol parts has poor temperature characteristics, and No. 24 in which the amount d exceeds 4.5 mol parts has a low relative dielectric constant. No18 where the SiO ₂ amount e is less than 0.75 mol part
No. 31 has poor sinterability, and e is more than 2.0 mol parts.
Has low dielectric constant and poor insulation resistance. EXAMPLES As starting materials, BaCO ₃ powder having a purity of 99% or more, Ti
After mixing using O ₂ powder and CaCO ₃ powder, a solid-phase reaction was performed at 1000 ° C. to synthesize (Ba, Ca) TiO ₃ , and the particle size was 1.
It was pulverized to 5 μm or less. Next, this synthetic fine powder (Ba,
Ca) TiO ₃ and MnCO ₃ powder, MgCO ₃ powder with Y ₂ O
_{3, Gd 2 O 3, Dy} 2 O 3, Ho 2 O 3, Er 2 O 3, Yb 2 O
_At least one powder selected from the group consisting of Li ₂ CO 3
_{The three} powders and the SiO ₂ powder were each weighed so as to have the ratios shown in Table 7, and mixed with a dispersant and a dispersion medium in a ball mill to prepare a raw material slurry. [Table 7] An organic binder and a plasticizer were added to the slurry, and the mixture was sufficiently stirred and formed into a film by a doctor blade method. This film is stacked and cut after thermocompression bonding (vertical) 10 mm x (horizontal) 10 mm x (thickness) 0.5 mm
Sample was obtained. This sample was controlled at an oxygen partial pressure of 3 × 10 ⁵ Pa, and the carrier gas was nitrogen gas at 1250 ° C. for 2 hours.
Fired for hours. In the upper and lower surfaces of the finally obtained sintered body, In
An electrode for electrical characteristics was formed by applying a -Ga alloy. Next, in the same manner as in Reference Example 2 above, these evaluation samples were used to determine the relative dielectric constant, insulation resistance, dielectric loss tangent, and +25.
The rate of change of the capacitance at each temperature with respect to the capacitance at 100 ° C. was measured.
The change rate (aging rate) of the capacitance after time was calculated. Table 8 shows the results. [Table 8] Here, the insulation resistance was represented by the product (CR, MΩ · μF) of the capacitance (C, μF) and the insulation resistance (R, MΩ). As is clear from Tables 7 and 8, in No. 39, where the molar ratio x of Ca exceeds 0.025 mol part, the relative dielectric constant is low and the insulation resistance is low. Also, when the value of k is less than 0, N
In the case of o40, the insulation resistance is low, and the value of k is a / 50 or more.
In the case of o42, the sinterability was poor, the film was not densified, and the relative dielectric constant was low.
In the case of No. 43 to which Sm, which is a rare earth element having a large ionic radius, is added, the dielectric loss is large, the insulation resistance is low, and the temperature characteristics are poor. In contrast to these comparative examples, the samples of the present invention all have a relative dielectric constant of 2500 or more and a dielectric loss tangent (tan δ).
Was 1.0% or less, the insulation resistance was 2700 MΩ · μF or more, and the temperature change rate of the relative dielectric constant was ± 15% or less, showing excellent characteristics. As described in detail above, the non-reducing dielectric ceramic composition of the present invention has a firing temperature in the range of 1150 to 1350 ° C. and an oxygen partial pressure of not more than the equilibrium oxygen partial pressure of Ni / NiO. , The relative dielectric constant, dielectric loss tangent, insulation resistance,
Since it shows excellent characteristics in the temperature characteristics of relative permittivity, it is excellent in practicality as a dielectric ceramic composition for a laminated ceramic capacitor using an internal electrode containing nickel as a main component.

──────────────────────────────────────────────────の Continuing on the front page (72) Inventor Masahiko Nakanishi 1810 Takagicho, Kawauchi City, Kagoshima Prefecture Kyocera Co., Ltd.Katsushima Kawauchi Plant (72) Inventor Katsuhiro Oda 1810 Takashirocho, Kawauchi City, Kagoshima Prefecture (72) Inventor Takashi Maeda 1810 Takagi-cho, Kawauchi-shi, Kagoshima Prefecture Kyocera Inside the Kagoshima Sendai Plant (56) References JP-A-63-103861 (JP, A) JP-A-4-264305 (JP, A) JP-A-4-264306 (JP, A) JP-A-60-119006 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) H01B 3/12 303 C04B 35/46 H01G 4 / 12 358

Claims (1)

(57) [Claims 1] The composition formula based on the molar ratio of metal elements is 100
(Ba _1-x Ca _x ) _{1 + k} TiO ₃ + aRE ₂ O ₃ + bMnO +
cMgO + dLi ₂ O + eSiO ₂ (RE is Y, Gd,
Dy, Ho, Er and Yb), a, b, c, d, e, x and k in the formula are 0.25 ≦ a ≦ 2.50 0.05 ≦ b ≦ 0.50 0.50 ≦ c ≦ 8.00 1.50 ≦ d ≦ 4.50 0.75 ≦ e <2.00 0 <x ≦ 0.025 0 ≦ k <a / 50 Non-reducing dielectric porcelain composition.