JPS59114704A - High dielectric porcelain 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 Field of Industrial Application The present invention relates to a high-permittivity ceramic composition containing barium titanate as a main component and having a high dielectric constant and a dense ceramic structure.

Conventional Structures and Their Problems Many ceramic capacitor compositions based on barium titanate have been known in the past. As is well known, barium titanate is a unique ferroelectric substance that has a cubic perovskite structure at high temperatures.
Below 120°C, the C-axis is slightly elongated to become a tetragonal crystal, and further changes to an orthorhombic crystal around 0°C and a rhombohedral crystal near -so'c.

The above-mentioned phase transition point near 120° C. is particularly referred to as a single point, and beyond this point, it exhibits paraelectricity at higher temperatures and exhibits ferroelectricity at lower temperatures. And, at one point, the dielectric constant exhibits an extremely high value of about 1000. Here, barium titanate alone cannot provide a high dielectric constant at room temperature. By moving the high dielectric constant of barium titanate to the low temperature side, many attempts have been made to commercialize small capacitors with appropriate capacitance near room temperature.

The additive that shifts the temperature at which the peak value of the dielectric constant occurs is called a shifter, and is B a S n 03 .

5rSn03. C1aSn03. PbSnO3, Cu5
nO3.

Zn5n03. stannates such as CdSnO3, BaZr
Zirconate salts such as O3°C1aZr03, 5rZr03 and 5rTiQ3.

Titanates such as P b T i O3 are generally known and have the strongest effect as a shifter in the order listed above. A barium titanate-based porcelain container/container using these shifters has been used as a single plate type with a reed. However, with recent advances in stacked chip technology, 30~1
A dielectric sheet with a diameter of approximately 0.00 μm can be easily obtained, and so-called multilayer ceramic chip capacitors, in which many layers of this thin film are laminated with electrodes sandwiched between them, have entered various electronics industries. are increasingly being used as such laminated thin film dielectrics. However, in conventional single-plate ceramic capacitors, the dielectric thickness is as thick as 100 μm to 10,000 μm.
10μm to 20μm for multilayer ceramic chip capacitors
Because it is thin (m), it receives an electric field strength of 5 to 10 times more. Therefore, there is a need for a composition that has less dependence on sag pressure than conventional single-plate capacitors. Furthermore, as the dielectric layer becomes thinner, structural defects in the ceramic become more likely to appear in the characteristics, so it is desirable that the crystal grains be uniform and fine, and that the number of pores be small and small.

In this background, the present inventors filed the patent application No. 57-1.
No. 6809 has already provided a high dielectric constant ceramic composition that has a high dielectric constant, has few ceramic structural defects, has low voltage dependence, and has a high withstand voltage. That is, BaT
It is a high dielectric constant ceramic composition consisting of 1 mole part to 10 mole part of iO3.

However, with this composition, the insulation resistance was somewhat low and the color was bright red, so that the palladium electrodes of the multilayer ceramic chip capacitor were visible through it, resulting in quality problems.

OBJECT OF THE INVENTION The present invention seeks to eliminate the above-mentioned drawbacks, and aims to obtain a high dielectric constant ceramic composition that has higher insulation resistance properties and at the same time does not allow palladium electrodes of a multilayer ceramic chip capacitor to be seen through the ceramic. With the goal.

Structure of the Invention In order to achieve this object, the high dielectric constant ceramic composition of the present invention contains 100 mol parts of BaTiO3, GeO, -(7±1
) and 27±1 molar parts of TiO are added to a small amount of niakel oxide (NiO) to a ceramic composition.

This structure improves the insulation resistance, and also reduces the brightness of the coloring of the porcelain, and the palladium electrode of the laminated ceramic molding container is no longer visible through the magnetism, improving the quality. The invention will be explained in detail on the basis of examples.

First, barium titanate (BaTiO3) was synthesized as follows. That is, barium carbonate (BaCo3) and titanium oxide (TiO2) are CB 2L)/(T i )
Mix with an accuracy of ratio 1.000±0.005, 11oO
After calcining at ~1150'C, it was pulverized to obtain BaTiO3.

For 100 mol parts of this BaTiO3, CeO2-(
7±1) molar parts and TiO27±1 molar parts were added, and further added at a ratio of Nio f:ftm and mixed.

A binder was added to this mixture, the mixture was granulated, formed into a rectangular plate shape, and fired at a temperature in the range of 1250 to 1350°C. After this, a silver electrode was formed.

FIGS. 1A, B, and 0 are diagrams showing the relationship between the amount of NiO added and electrical characteristics. As is clear from FIG. 1, the dielectric constant e shown in FIG. 5 tends to gradually decrease when the amount of MnO□ added exceeds 0.2 mol part.

Also, the i constant loss angle -δ shown in Figure 1B is 0.
．． If it exceeds 5 mole parts, it tends to increase.

Furthermore, the insulation resistance IR shown in FIG. 1C gradually increases as the NiO content increases.

Next, regarding the composition of the various amounts of NiO added above, the second
We prototyped a multilayer ceramic chip capacitor as shown in the figure. In Fig. 2, 1 is a dielectric and the thickness between the electrodes is 3.
6 μm, 2 is a palladium electrode, and 3 is a silver terminal electrode.

FIGS. 3A, B, and C show the relationship between the amount of N10 added and the electrical properties of such laminated ceramic plates and condensers. Further, the shaded area indicates the range where the palladium electrode can be seen through the dielectric layer having a thickness of 35 μm. As is clear from FIG. 3, the dependence on the amount of NiO added is relatively large compared to the electrical characteristic values of the square plate shown in FIG. First, when N'i0 is added in excess of O-2 molar parts, the dielectric constant ε decreases extremely as shown in Figure 3A, but within 0.2 molar parts, the dielectric constant ε hardly changes. . In addition, as shown in FIG. 3B, the insulation resistance IR is N'i0 at 0.2 molar parts.
The value is approximately 5 times higher than that without additives. Furthermore, as shown in FIG. 3G, the contact loss δ becomes large at 0.3 mole part or more.

From the above results, the range of the optimum amount of NiO to be added is limited to between 0.06 mol part, at which the palladium electrode is not visible, and 0.2 mol part, at which the dielectric constant begins to drop suddenly.

In addition, the average grain size is 2 to 3μ throughout the examples.
m, and the pore size was also below 2 to 3 μml.

Effects of the Invention From the above, the composition of the present invention is disclosed in Japanese Patent Application No. 57-1.
Similar to the composition of No. 6809, it has the advantage of being able to obtain a small, dense ceramic with fine grains and few bores, as well as the significant improvement in insulation resistance and laminated ceramic chip of patent application No. 16809/1986. It is possible to provide a ceramic capacitor in which the palladium electrode cannot be seen through. In particular, it is extremely effective as a galvanic composition for multilayer ceramic chip capacitors with YsD characteristics according to EIA standards, and its industrial value is great.

Although barium titanate was synthesized in the examples, it is of course possible to use commercially available barium titanate.

[Brief explanation of drawings]

Figure 1 A, B, C shows N'i0 for the composition of the invention.
Figure 2 is a cross-sectional view of a multilayer ceramic dielectric capacitor to which the composition of the present invention is applied, and Figures A, B, and C are graphs showing the amount of Ni added and the characteristics of the square plate dielectric.
FIG. 3 is a diagram showing the amount of O added and the characteristics of a multilayer ceramic chip capacitor. Name of agent: Patent attorney Toshio Nakao and 1 other person No. 1
Fig. 2

Claims (1)

[Claims] 10 mol parts of barium titanate (BaTiO3). Cerium oxide (Ceoz) - (7 ± 1) mole parts, titanium oxide (TiO□) 7 ± 1 mole parts and 2.7 Kel oxide (N
iO) A high dielectric constant ceramic composition comprising 0.05 to 0.2 mole part.