JPS62278163A - Non-reductive dielectric ceramic 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] 3. Detailed Description of the Invention Field of Industrial Application] The present invention relates to a non-reducible dielectric ceramic composition for a ceramic capacitor, particularly a laminated ceramic capacitor having an internal electrode made of nickel. It is.

[Conventional technology]

Conventionally, multilayer ceramic capacitors are generally made by laminating multiple sheets of dielectric material mainly composed of BaTi0:l with internal electrodes coated on the surface, and the internal electrodes of each sheet are alternately connected in parallel to a pair of external connections. It is connected to an electrode and is formed by sintering and integrating it. Such laminated ceramic capacitors have come to be used in a wide range of electronic circuits as electronic components have rapidly become smaller with the recent advances in electronics.

However, this conventional dielectric material mainly composed of BaTiO3 needs to be sintered at a high temperature of 1250°C to 1350°C, and when this material is used as the dielectric of a multilayer ceramic capacitor, the internal electrodes are Palladium (melting point: 1555°C), an expensive precious metal that does not melt or oxidize at the sintering temperature of the body, or its alloys is used, and the number of internal electrodes is particularly large for products with large capacitance. Although the conventional multilayer ceramic capacitors have high capacitance efficiency, other excellent dielectric properties, and high reliability, the price has been a major obstacle to their progress.

Therefore, attempts have been made to use inexpensive base metals, such as nickel, as the internal electrodes in order to overcome the drawback of the conventional multilayer ceramic capacitors being expensive. However, when a base metal such as nickel is used as an internal electrode, when simultaneously sintering a dielectric material such as barium titanate (BaTiOz) and a base metal internal electrode, the conditions are such that the base metal can be sintered as a metal film without being oxidized. is Ni/
The equilibrium oxygen partial pressure of NiO is approximately 3X10 at 1300℃
-'εtn, the oxygen partial pressure must be lower than that, and in this case, a dielectric made of barium titanate or its solid solution is generally reduced and loses its insulating properties under the above oxygen partial pressure. It has the disadvantage that practical dielectric properties cannot be obtained as a multilayer ceramic capacitor.

On the other hand, barium titanate solid solution (Ha, Ca, 5R) is used as a non-reducible dielectric ceramic composition that can be used as a multilayer ceramic capacitor having internal electrodes such as nickel.
Ties is a basic oxide (Ba.

Japanese Patent Publication No. 57-42588 discloses a non-reducible dielectric ceramic composition in which Ca, 5r)0 is in excess of the stoichiometric ratio with respect to the acidic oxide TiO□, and base metals such as nickel can be used as internal electrodes. It has been proposed in et al.

In general, in an ABOi type crystal, the A ion, which is larger than the B ion and has 12 coordinations to oxygen, is in excess of the stoichiometric ratio to the B ion located at the center of the oxygen octahedral (perovskite) structure. It is known that in the case of It has been improved. However, the dielectric ceramic composition described in the above-mentioned publication had the disadvantage that the rate of change in dielectric constant with temperature was large and the dielectric properties deteriorated.

In addition, as a high dielectric constant dielectric ceramic composition with a small temperature change rate of dielectric constant, we have added bismuth stannate (Bit) to BaTiO3.
(SnOi):+), bismuth zirconate (Bi
There are those to which bismuth-based compounds such as t(Zr(h)z), nickel zirconate (NiZrC3), and magnesium zirconate (MgZrOz) are added. This is because the maximum value of the dielectric constant near the Curie point of BaTi0z is lowered by the strong depressor effect of the hismuth-based compound 1i or nickel zirconate or magnesium zirconate, and the temperature change rate of the dielectric constant is reduced. However, when a dielectric material in which a base metal such as nickel is used as an internal electrode and a bismuth-based compound, nickel zirconate, or magnesium zirconate is added to BaTi0'z is co-fired at a temperature below the equilibrium oxygen partial pressure of Ni/NiO, the dielectric material This has the disadvantage that the body is reduced and loses its insulating properties, and as a result, satisfactory dielectric properties cannot be obtained.

[Purpose of the invention]

In view of the above-mentioned drawbacks, the present invention has been developed based on the results of various experiments.
CaZr0:l l MnO and Y2O:l at the same time
It has been found that by adding , it is possible to satisfy H, I, and A standards with a temperature change rate of dielectric constant within ±15%, and to improve the increase in relative dielectric constant.

The present invention is based on the above findings, and the present invention is based on the above findings. , CaZr0.
, gate n.

In the composition in which Y2O3 is added to the composition system, 12
Oxygen partial pressure between 50℃ and 1350℃ is 3×10
It does not reduce when fired in an atmosphere of ATM to 3 Xl0-" ATM, and base metal powder particles such as nickel used as internal electrodes do not oxidize and are sintered as a metal film, resulting in a high dielectric constant and excellent properties. It has good insulation properties,
Another object of the present invention is to provide a highly economical high-permittivity non-reducible dielectric ceramic composition that has a small rate of change in dielectric constant over a wide temperature range and a small dielectric loss tangent.

[Means for solving problems]

According to the present invention, the compositional formula is (1-x-y) BaTi0. +xCaTiO,
↓yMn00.010≦x≦0.045 o, oos≦y≦0.02 For the main component expressed as By containing 2, the above object is achieved.

The present invention will be explained in detail below.

The non-reducible dielectric ceramic composition of the present invention has B as a main component.
aTiO3, CaTi0. , MnO is characterized in that Y2O3 is added to the aforementioned main components consisting of BaTiO3 and CaZr0. By adding at the same time, a depressor effect similar to that of the bismuth-based compound, nickel zirconate, or magnesium zirconate can be obtained, and the maximum value of the dielectric constant near the Curie point of BaTi0= is lowered, and the temperature of the dielectric constant is lowered. This effectively works to reduce the rate of change and improve insulation resistance.

In addition, MnO forms an acceptor level,
By adding these, donor level electrons formed by oxygen defects generated during firing under a low oxygen partial pressure of 3 Xl0-"aLm to 3 Xl0-"atm can be converted to acceptor levels formed by adding MnO. By recombining at levels, dielectric ceramics are prevented from becoming semiconductors and maintain high insulation properties.

In addition, Y! 0. The amount of addition is 0.2 to the main component.
5 to 1.0 mol χ, preferably the amount of yzoa is 0.25
If it is less than 1.0 mol χ, the rate of temperature change on the low temperature side will increase and the insulation resistance will decrease, while if it exceeds 1.0 mol χ, the rate of temperature change on the high temperature side will tend to be large and the relative permittivity will decrease.

〔Example〕

Next, the present invention will be explained based on examples.

BaTiOs and TiOs were subjected to solid-phase reaction at 1150°C and dCaCOz and Zr0z were subjected to solid phase reaction at 1220°C as raw materials, respectively, to form BaTi0t and CaZr0. was synthesized and pulverized. Next, the synthetic fine powder BaTiO3 and C
Y2O3 was added to aZr0* and MnCO3, each was weighed so as to have the proportions shown in Table 1, and mixed together with a dispersant and a dispersion medium in a ball mill to prepare a raw material slurry. Next, an organic binder was added to this raw material slurry along with plasticity, and after thorough stirring and vacuum defoaming, it was formed into a film using a doctor blade method. Next, 20 sheets of the above-mentioned films were stacked and bonded under heat using a press.
011II111 It was cut into a width of about 10 mm. This sample was heated to an oxygen partial pressure of 3 Xl0-"atm to 3 X 10-"a
1250 with N2 gas as the carrier gas.
It was baked at 1350°C for 2 hours. Indium-gallium (In-Ga) is formed on both the upper and lower surfaces of the finally obtained fired body.
) Alloy was applied.

Next, after leaving these evaluation samples at room temperature for 48 hours,
Frequency: 1.0KHz, input signal level: 1. Capacitance and dielectric loss tangent were measured at αVrns, and relative permittivity was calculated from the capacitance. Thereafter, a DC voltage of 50 V was applied for 1 minute, and the insulation resistance at that time was measured. Also, =55℃ to +12
Capacitance and dielectric loss tangent were also measured in the temperature range of 5° C. under the same conditions as above, and the rate of change in capacitance at each temperature with respect to the capacitance at +25° C. was calculated.

The above results are shown in Table 1. However, the amounts of additives added in the table are expressed as the molar fraction of Y2O to the main component composition.

Also, the same (insulation resistance is the product (C-R) of capacitance (C1μF) and insulation resistance (R, MΩ).

Expressed in MΩ・μF).

As is clear from Table 1, when CaZr01 is less than 1 mol χ, the temperature change rate at -55°C is large, while when it exceeds 4.5 mol χ, the temperature change rate at +95°C is large. is large. In addition, N116 where MnO is less than 0.5 mol χ
has a low insulation resistance, and 11h9, which exceeds 2χ, has a low dielectric constant. 11h1 where the amount of Y2O3 is less than 0.25 mol χ
For both 0°11, the temperature change rate at -55°C is large,
For case 1'4 with a concentration exceeding 1.0 mol χ, the rate of temperature change at +95°C is large. In contrast to these comparative examples, sample size 2 of the present invention
, 3, 4, 7, 8.12.13 all have a relative dielectric constant of 3000 or more, a dielectric loss tangent of 1.13 or less, and an insulation resistance of 11.
00 (MΩ・μF) or more.

〔Effect of the invention〕

As detailed above, the dielectric ceramic composition of the present invention is B
By adding a small amount of Y2O to the main component consisting of aTiOx, CaZr0=, and MnO in a specific range, equilibrium oxygen with an oxygen partial pressure of Ni/NiO can be created at a firing temperature of 1250°C to 1350°C. Can be fired simultaneously with nickel metal electrodes under firing conditions below partial pressure.
Moreover, it satisfies all the dielectric properties of sintered porcelain, and in addition, nickel metal fine particles are sintered into a metal film without oxidizing, so it is sufficient as a dielectric porcelain for laminated porcelain capacitors with nickel as internal electrodes. It is understood that it is practical.

Claims (1)

[Claims] The compositional formula is (1-x-y)BaTiO_3+xCaTiO_3+y
Y_2O_3 as an additive to the main component MnO0.010≦x≦0.045 0.005≦y≦0.02
A non-reducible dielectric ceramic composition, characterized in that it contains 0.25 to 1.0 mol% of the main component composition.