JPS62256422A - Laminated type porcelain capacitor - 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 [Field of Industrial Application] The present invention relates to a multilayer ceramic capacitor with nickel internal electrodes.

[Conventional technology]

Conventionally, a multilayer ceramic capacitor generally consists of laminating multiple sheets of dielectric material mainly composed of tlaTioz with internal electrodes coated on the surface, and the internal electrodes of each sheet are alternately connected in parallel to a pair of external connection electrodes. It is formed by connecting the two to one another and sintering them into one piece. 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 BaTi0i needs to be fired 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 firing temperatures of Although the conventional multilayer ceramic capacitors have high capacitance efficiency, other excellent dielectric properties, and high reliability, the cost has been a major impediment to its 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 made of barium titanate (BaTi0z) or the like and a base metal internal electrode, the conditions under which the base metal can be sintered as a metal film without oxidation are required. is Ni/
The equilibrium oxygen partial pressure of NiO is approximately 3χ10 at 1300℃
-'atm, the oxygen partial pressure must be lower than that, and in this case, the dielectric material made of barium titanate or its solid solution is generally reduced and loses its insulating properties under the above oxygen partial pressure. The drawback is that practical dielectric properties for a multilayer ceramic capacitor cannot be obtained.

On the other hand, barium titanate solid solution (Ba, 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.
Tie, which is a basic oxide (Ba.

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

Generally, in an ABCh type crystal, the B ion located at the center of the oxygen octahedral (perovskite) structure has 12 coordinations with respect to oxygen, which is larger than the B ion. It is known that in the case of It has improved characteristics. 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, BaTiOs and bismuth stannate [B12 (
SnOz)v), bismuth zirconate (Bi2(
There are products to which bismuth-based compounds such as Zr03) 3), nickel zirconate (NiZrOz), and magnesium zirconate (MgZr(h)) are added. This reduces the maximum value of the dielectric constant near the Curie point of BaTi0:+ and reduces the temperature change rate of the dielectric constant.However, a base metal such as nickel is used as the internal electrode, and a bismuth-based compound or a bismuth-based compound or When a dielectric material to which nickel zirconate or magnesium zirconate is added is co-fired below the Ni/NiO equilibrium oxygen partial pressure, the dielectric material is reduced and loses its insulating properties, resulting in a satisfactory dielectric material. This had the disadvantage that the characteristics could no longer be obtained.

Furthermore, the dielectric material itself is not reduced even when fired near the equilibrium oxygen partial pressure of Ni/NiO, and BaTiO is used as a non-reducible high dielectric constant dielectric ceramic composition with a small temperature change rate of dielectric constant.
3-Mn0-MgO based composition is disclosed in JP-A-57-71866.
It is proposed in the publication No.

This is because MnO and MgO have the effect of suppressing the reduction of BaTi0z, and the dielectric is not reduced even when fired near the equilibrium oxygen partial pressure, and has sufficient insulation properties. Since it has a similar depressor effect, the rate of change in dielectric constant with temperature is reduced. However, the dielectric ceramic composition described in the above-mentioned publication has a low dielectric constant, and when the amount of MgO added is increased,
, 1. A. Standards (Electronic Indus
tries As5ocation 5tandar
d) Temperature change rate of dielectric constant (however, -55°C to +125°C
If the temperature range (based on +25°C) is within ±15%, the dielectric constant becomes even lower to 2200 or less, which has the disadvantage that practical dielectric properties cannot be obtained.

[Purpose of the invention]

The main purpose of the present invention is to solve the above-mentioned problems. Specifically, the present invention uses nickel as an internal electrode, has a high dielectric constant, excellent electrical insulation, has a small dielectric loss tangent, and has a dielectric constant over a wide temperature range. An object of the present invention is to provide a multilayer ceramic capacitor that has a small rate of change with temperature and is extremely economical.

[Means for solving problems]

According to the present invention, the composition formula of the dielectric is (1-x
-y -z)BaTiO3+xCaZrO++yMnO
+zMgO However, 0.003≦x:S 0.0230.
005≦y:! For the main component represented by aO,030 0,010≦2≦0.080, YzOs is added as an additive in the proportion to the above MgO as shown in Figure 1 below ^, B, C,0
, EMgO (mol χ”) Y2O3 (mol χ) A
8.00 2.00B 5.0
0 0.25C1,000,25 [) 1. The above object can be achieved by using nickel as an internal electrode in the dielectric by adding nickel within the range surrounded by QO 1,00 E 6.00 2.50.

Note that FIG. 1 is a binary system diagram showing the composition range of MgO and YzOs in the dielectric used in the present invention.
gO (mol χ) is the mole fraction to the entire main component, Y2O
2 (mol χ) is expressed as a mole fraction relative to the total amount of the main component and additives.

1 year old Figure 2 V is a sectional view of the multilayer ceramic capacitor of the present invention.

In the multilayer ceramic capacitor of the present invention, as shown in FIG. 2, a plurality of internal electrodes 2 made of nickel are formed in a dielectric 1. The internal electrodes 2 are alternately connected to external electrodes 3 formed at both ends.

According to the present invention, a dielectric having excellent non-reducing property is used as the dielectric, and in particular, as described above, B a T i O:l l
A main component containing Ca Z r 03 +MnO and MgO in a specific ratio and Y2O as an additive in a specific ratio is used.

This dielectric material is made of rare earth element oxide Y2O2 with BaT
i0*.

By simultaneously adding CaZr0z+ MgO and MnO, a depressor effect similar to that of the bismuth-based compounds, nickel zirconate, or magnesium zirconate can be obtained, and the maximum value of the dielectric constant near the Curie point of BaTi0= can be lowered. This is effective in reducing temperature changes in dielectric constant and improving insulation resistance.

In addition, when nickel is used as the internal electrode, Ni/N
Donor level electrons formed in the dielectric by oxygen defects generated during firing in an atmosphere of 3×lO to 10 to 3×to-” ATM, which is the equilibrium oxygen partial pressure of iO at 1250°C to 1350°C, are transferred to MnO and MgO. By adding , recombination can occur at the acceptor level, thereby suppressing the dielectric ceramic from becoming a semiconductor and maintaining high insulation properties.

Therefore, as a ceramic capacitor, a capacitor having a high relative dielectric constant and insulation resistance, a small dielectric loss tangent (tan δ), and a small fluctuation in dielectric constant and capacitance with respect to temperature changes can be obtained.

Manufacturing of the ceramic capacitor of the present invention will be explained. When manufacturing dielectrics, first, BaCO5* is used as a starting material.
Using powder of CaCO3*Ti01+Zr0t, Ba
Ti0z and CaZr0. Synthesize. BaTi01 is synthesized from BaC0* and Ti0z at a temperature of 1150°C, and CaZr0i is synthesized from Cacas, zr□ at a temperature of 1220°C by solid phase reaction. The synthesized BaTiO3 and CaZrO3 were ground. After, MnCO
5, MgCO5 and Y: 0. to prepare a slurry. The obtained slurry is formed into a film (sheet) by a known forming method, such as a doctor blade method or a calendar roll method.

On this sheet, a nickel paste containing fine nickel powder having an average particle diameter of 1.5 μm or less is printed with a nickel internal electrode by a printing method, for example, a screen printing method. Thereafter, a plurality of printed sheets are stacked and fired in a reducing atmosphere. The firing conditions were a firing temperature of 1250°C to 1350°C, and an oxygen partial pressure in the atmosphere of 3X10-” to 3
It is desirable that it is Xl0-"atm.

The final product is made by applying external electrode forming paste to both ends of the sintered body obtained as described above.
Reducing atmosphere at 50℃, especially oxygen partial pressure IQ-16 to 10
It is obtained by firing in an ATM atmosphere.

Examples of the material for the external electrode include silver, silver-palladium, nickel, copper, and copper-nickel. In the present invention, nickel, copper, or copper-nickel is preferable from the viewpoint of adhesiveness with the internal electrode.

In addition, according to the present manufacturing method, it is desirable to perform heat treatment in the air at a low temperature of 250 to 500° C. for the purpose of removing the organic binder after sheet lamination and before firing.

The invention is illustrated by the following example.

〔Example〕

(Preparation of sample) BaC0++CaC0:++TiO,, as starting material
Using Zr0z and BaTi0* and CaZr0i at 115
It was synthesized by solid-phase reaction at 0°C and 1220°C and pulverized. Next, synthesized BaTiOs, CaZ
For r0z, MnCO3, MgCO3 and Y2O,
The dielectric materials were 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 separately prepare a raw material slurry.

A plasticizer and an organic binder were added to the resulting slurry, thoroughly stirred and defoamed under vacuum, and then formed into a film using a doctor blade method. On this sheet, the average particle size is 0.7 μm.
Electrodes were printed using a screen printing method using a nickel paste consisting of fine nickel powder, an organic binder, and a solvent using a predetermined plate making method.

In the same way, 21 sheets with electrodes printed on them were stacked, sheets with no electrodes printed on top and bottom were stacked, and then a cutting guide sheet with carbon paste printed in a bullet shape was stacked on top of that, and after thermocompression bonding, shrinkage was achieved. Approximately 3゜6tata, width approximately 1
．． A chip-shaped sample consisting of 20 layers was obtained by cutting into 811I11.

After heat treating this sample at 300°C for 2 hours, the oxygen partial pressure was increased from 3Xl0-'' to 3X using Nt as a carrier gas.
The temperature was controlled at 10-'atm, and firing was performed at 1250°C to 1350°C for 2 hours. A nickel-copper paste was applied to both ends of the obtained sintered body, and after drying, the carrier gas was N2 and the oxygen partial pressure was controlled to about I
The electrode for external connection was baked at ℃ for 10 hours.

(Sample measurement method) After leaving the obtained sample at room temperature for 48 hours,
．． llz to 0, input signal level 1. Capacitance and dielectric loss tangent were measured at OVrms. After that, DC voltage 50
V was applied for 1 minute, and the insulation resistance at that time was measured. In addition, capacitance was measured in the same manner as above in the temperature range from -55°C to 125°C, and the rate of change at -55°C, -10°C, +95°C, and +125°C with respect to the capacitance at +25°C was calculated. did.

The measurement results are shown in Table 1. The insulation resistance in Table 1 is the product CXR of capacitance IC (μF) and insulation resistance R (MΩ).
It was expressed in (MΩ・μF).

As is clear from Table 1, MgO is less than 1 mole χ! 1kLl has low CR and h (magnetic 2,9 where h is 0)
．． 21 has low CR and large temperature change at -55℃,
The same is true for case 26 in which Mg06 mol χ and Y2O2 is 0.75 mol χ.

On the other hand, YzOi is 1.25-T-ruX 5Mg01.0
-T-7L4) rhe has a large temperature change at +95°C, and MgO is 3 mol χ, YzOs 2.0 mol χ
11kL13 and Mg05mol χ, Y*0*2.
Sintering was difficult at 5 mol χ. Furthermore, MnO is 0.5
CR is low (, Mn
Na2O,35, in which O exceeds 3.0 mol χ, has a low CR, and Na35 has a low capacitance.

Magnet 30, in which Y2O, is 3 mol χ, has a low capacitance, and M
Even in 1lh38 where gO is 8.5 mol χ, the capacitance is low and the temperature change at -55°C is large.

In addition, patient 7 with CaZrO3 of 0 had a low CR and -5
The temperature characteristics at 5°C are also poor.Arashi 15, which has 2.5 mol χ, has poor temperature characteristics at +95°C.

In contrast to these comparative examples, all of the other samples of the present invention showed excellent characteristics, with a capacitance of 40 μF or more (dielectric constant of 2
200 or more), a dielectric loss tangent of 2.5% or less, an insulation resistance of 1000 MΩ or more, and a temperature change (-55°C to +125°C) within ±15%.

(Effects of the Invention) As detailed above, according to the present invention, nickel is used as the internal electrode, and BaT io 31 CaZr is used as the dielectric.
0, .

By adding Y2O in a specific ratio to the main component consisting of MnO and MgO in a specific ratio, the capacitance is 40μF or more, the insulation resistance is 1000MΩ or more, and the dielectric loss tangent is 2.
．． 5% or less and temperature change (-55℃ to +125℃)
It is possible to obtain a multilayer ceramic capacitor that has excellent characteristics of within ±15% and is also highly economical.

[Brief explanation of drawings]

FIG. 1 is a binary diagram showing the composition range of MgO and YtOs in the dielectric used in the present invention, and FIG. 2 is a sectional view of the multilayer ceramic capacitor of the present invention. 1... Dielectric 2... Internal electrode 3... External electrode Fig. 1 0 0.5 1.0 1,5 2,0 2,5
3.0 Yasukaki 1 (moru%) (MoCh)

Claims (1)

[Claims] The compositional formula is (1-x-y-z)BaTiO_3+xCaZrO_3
+yMnO+zMgO However, 0.003≦x≦0.023 0.005≦y≦0.030 0.010≦z≦0.080 In addition to the above MgO, Y_2O_3 was added as an additive to the main components shown in Figure 1. In, the following A, B, C, D
, E. A multilayer ceramic capacitor characterized by having an internal electrode made of nickel in a dielectric material having a composition that satisfies the range surrounded by points , E. MgO Y_2O_3 (mol%) (mol%) A 8.00 2.00 B 5.00 0.25 C 1.00 0.25 D 1.00 1.00 E 6.00 2.50