JPH0821258B2 - Dielectric porcelain composition - Google Patents

Description

The present invention has a high dielectric constant, a small temperature coefficient, and a good Q
The present invention relates to a dielectric ceramic composition having excellent insulation resistance and high insulation resistance.

2. Description of the Related Art Conventionally, a dielectric having a small temperature coefficient has been required as an element for a capacitor, and the following system is known as a dielectric ceramic composition.

MgO-TiO ₂ -CoO system La ₂ O ₃ -2TiO ₂ -CaTiO ₃ -2MgO-TiO ₂ system TiO ₂ -BaTiO ₃ -Bi ₂ O ₃ -La ₂ O ₃ system SrZrO ₃ -SrO-Nb ₂ O ₅ -CaTiO system ₃ based iNVENTION problems to be solved However, these compositions have low dielectric constant, also, SrZrO ₃
-SrO-Nb ₂ O ₅ -CaTiO ₃ system is goodness Q also there is a problem that bad.

The present invention has a high dielectric constant, a small temperature coefficient, and a goodness Q.
The object of the present invention is to obtain a dielectric porcelain which is excellent in and has a high insulation resistance.

Means for Solving the Problems In order to solve this problem, the dielectric ceramic composition of the present invention has the general formula xBaO-y [(TiO ₂ ) _1-m (ZrO ₂ ) _m ] -Z [(Nd ₂ O ₃ ) _1-n (Sm ₂ O ₃ ) _n ] Is expressed, x, y, z is 0% by weight of PbO with respect to the composition in the range of the molar ratio surrounded by the points a, b, c, d shown below.
It is characterized in that it is added in an amount of 15% by weight or less except for.

FIG. 1 is a triangular diagram showing the composition range of the main component of the composition according to the present invention, and the reason why the composition range of the main component is limited will be described with reference to the drawing. In the area A, it becomes difficult to sinter, and the dielectric constant, the goodness Q, and the insulation resistance decrease. In the B range, the temperature coefficient becomes too large on the negative (-) side, which is not practical. In the C region, the temperature coefficient increases to the + (plus) side and the inductivity is small. In the D region, it becomes difficult to sinter, and the dielectric constant, goodness Q, and insulation resistance decrease. Also, 0
In the range of <m ≦ 0.25, increasing m increases the temperature coefficient +
By shifting to the (plus) side and selecting an appropriate composition, a composition with a large dielectric constant can be obtained near the temperature coefficient NPO. m
Of more than 0.25 makes it difficult to sinter and lowers the dielectric constant, goodness Q and insulation resistance. Further, in the range of 0.05 ≦ n <1.00, when n is increased, the temperature coefficient shifts to the + (plus) side, and by selecting an appropriate composition, a composition having a large dielectric constant near the temperature coefficient NPO can be obtained. If n is less than 0.05, the temperature coefficient increases to the negative (-) side, which is not practical. Regarding the addition of PbO, the dielectric constant can be increased as the addition amount is increased, and the temperature coefficient can be shifted to the + (plus) side. By selecting an appropriate addition amount, the temperature coefficient near the NPO can be improved. A composition having a large dielectric constant can be obtained.

The present invention further comprises at least one element selected from the group consisting of manganese, chromium, iron, nickel, cobalt and silicon with respect to the above-mentioned main component, MnO ₂ and C, respectively.
_{r 2 O 3, FeO, NiO} , in terms of CoO and SiO ₂ of the main component 0.05
It can be made to have a composition in which the content is added up to 1.00% by weight. These additives have the effect of improving the sinterability of the porcelain. When the amount is less than 0.05% by weight, there is no effect, and when the amount exceeds 1.00% by weight, the dielectric constant is lowered and is not practical.

Effect With the dielectric ceramic composition of the present invention, it is possible to obtain a dielectric ceramic having a high dielectric constant, a small temperature coefficient, an excellent Q, and a high insulation resistance.

Examples Hereinafter, the present invention will be described with reference to specific examples.

Example 1 As a starting material, chemically highly pure BaCO ₃ , TiO ₂ , ZrO ₂ and Nd ₂ O were used.
₃ , Sm ₂ O ₃ and PbO powders were weighed so as to have the composition shown in Table 1, put in a rubber-lined ball mill equipped with agate balls together with pure water, wet-mixed, and dehydrated and dried. This dry powder was put in a crucible of high alumina quality and calcined at 1000 ° C. for 2 hours. The calcined powder was put together with pure water in a rubber-lined ball mill equipped with an agate ball and wet-pulverized. The pulverized product was dehydrated and dried, and then 9% by weight of a polyvinyl alcohol solution having a concentration of 5% by weight as a binder was added to the powder to homogenize it, followed by sizing through a 32 mesh sieve. The sized powder was molded into a diameter of 15 mm and a thickness of 0.4 mm at a molding pressure of 1 ton / cm ² using a mold and a hydraulic press, and the molded product was placed in a zirconia bowl and placed in air at the temperature shown in Table 1. It was fired for 2 hours to obtain a dielectric porcelain having the composition shown in Table 1.

The electrical characteristics of these samples are as follows: silver electrodes are printed on both sides of the samples, the dielectric constant, goodness Q, and temperature coefficient are measured using a YHP digital LCR meter model 4275A. Measurement temperature 25 ° C, measurement voltage 1.0V _rms , The measurement frequency was 1 MHz. The temperature coefficient is based on the capacity value at 25 ° C,
It was calculated by the following formula.

Temperature coefficient (ppm / ℃) = [(C _{85 ℃} -C _{25 ℃} ) / (C _{25 ℃} × 60)] × 10 ^{6 For} insulation resistance, use YHP HR meter model 4329A.
It was determined by measurement with a measurement voltage of DC 50 V and a measurement time of 1 minute. The test results are shown in Table 1.

Example 2 As a starting material, chemically highly pure BaCO ₃ , TiO ₂ , ZrO ₂ and Nd ₂ O were used.
₃ , Sm ₂ O ₃ , PbO, MnO ₂ , Cr ₂ O ₃ , FeO, NiO, CoO and SiO ₂ powders were weighed so as to have the composition shown in Table 2, and thereafter the same as in Example 1. Then, a dielectric ceramic having the composition shown in Table 2 was obtained.

The test method for these samples is the same as in Example 1, and the test results are shown in Table 2.

Effects of the Invention As described above, according to the present invention, a dielectric ceramic having a high dielectric constant, a small temperature coefficient, an excellent goodness Q, and a high insulation resistance can be obtained. Further, the firing temperature can be lowered by adding manganese, chromium, iron, nickel, cobalt and silicon.

Further, since the obtained dielectric ceramic has a high dielectric constant, the element body can be made extremely small, which is effective for miniaturization of the circuit.

[Brief description of drawings]

FIG. 1 is a triangular diagram showing the composition range of the main component according to the present invention.

Claims (2)

[Claims] 1. A general formula xBaO-y [(TiO ₂ ) _1-m (ZrO ₂ ) _m ] -Z [(Nd ₂ O ₃ ) _1-n (Sm ₂ O ₃ ) _n ]. Is expressed, x, y, z is 0% by weight of PbO with respect to the composition in the range of the molar ratio surrounded by the points a, b, c, d shown below.
The dielectric ceramic composition is characterized by being contained in an amount of 15% by weight or less. 2. At least one selected from the group consisting of manganese, chromium, iron, nickel, cobalt and silicon.
The elements of the species are MnO ₂ , Cr ₂ O ₃ , FeO, NiO, CoO and SiO _{2 respectively.}
The dielectric ceramic composition according to claim (1), characterized by containing 0.05 to 1.00% by weight of the main component.