JPH01274411A - Semiconductor porcelain substance - Google Patents

Abstract

PURPOSE:To improve electric characteristics by combining strontium titanate and calcium titanate as main components, adding niobium oxide and yttrium oxide as assistants for controlling valence, and adding mixture of silica, manganese oxide and copper oxide as assistants for sintering. CONSTITUTION:One kind or two kinds among niobium oxide (Nb2O5) or yttrium oxide (Y2O3) are added by 0.1 to 0.4mol% as assistants for controlling valence to main component of 100mol% consisting of strontium titanate (SrTiO3) 97 to 80mol% and calcium titanate (CaTiO3) 3 to 20mol%. Furthermore, silica (SiO2) by 0.1 to 0.4mol%, manganese oxide (MnO2) by 0.05 to 0.2mol%, and copper oxide (CuO) by 0.05 to 0.2mol% are respectively added as assistants for sintering. Hereby, it can be made excellent in electric characteristics such as dielectric constant, dielectric dissipation factor, volume resistivity, electrostatic capacity temperature characteristic (TC value), etc.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a semiconductor ceramic material in which an insulating layer is provided at the grain boundaries of semiconductor ceramic.

[Prior art]

In recent years, grain boundary dielectric type semiconductor porcelain capacitors have been developed in which a highly insulating layer is provided as a dielectric material at the grain boundaries of semiconductor porcelain mainly made of barium titanate (BaTiO,2) or strontium titanate (SrTiO3). Semiconducting porcelain materials are widely used. This semiconductor ceramic material is first made of barium titanate (BaTiO2) or strontium titanate (SrTiO3) as a main material, and niobium oxide (NbzO3) as an auxiliary agent for valence control.
), yttrium oxide (Y2O2), dysprosium oxide (DyzOi), cerium oxide (Cent)
silicon oxide (SiO) as a sintering aid.
□), aluminum oxide (AlzQ3), manganese oxide (MnO2), copper oxide (CuO), manganese oxide (MnO2), copper decaoxide (CuO), bismuth oxide (B
i, 0. ) and sintered in a neutral or reducing atmosphere to obtain semiconductor porcelain.Next, in order to provide a dielectric layer at the grain boundaries of this semiconductor porcelain, manganese oxide (MnO□) , copper oxide (CuO), bismuth oxide (Bi
It was obtained by thermally diffusing metal oxides such as g(h) as the above-mentioned diffusing substance (Japanese Patent Publication No. 56-51820, Japanese Patent Publication No. 56-74913).

[Problem to be solved by the invention]

The electrical properties of the resulting semiconductor ceramic material [permittivity (εapp) + dielectric loss tangent (tan δ)] depend on what kind of material is used as the valence control aid or sintering aid.
1 Volume resistivity (ρapp) + Capacitance temperature characteristic (TC
value), etc.]. For example, barium titanate (B
In a semiconductor ceramic material obtained by adding dysprosium oxide (DyzOt) as a valence control agent to a main component of aTiO2), the dielectric constant is 60.000 to 8.
Although it is high at 0,000, the capacitance temperature characteristic (TC value) is 2
When the capacitance at 0°C is used as the reference value, -25°C to +
The maximum rate of change within the temperature range of 85℃ is as large as ±35%.
Furthermore, the dielectric loss tangent (tan δ) is also as high as 8%.

In addition, when strontium titanate (SrTiOi) is the main component and dysprosium oxide (DVz(h) or cerium oxide (CeO□) is added as a valence control agent, the dielectric loss tangent is as low as 2%. In addition, the capacitance temperature characteristic (TC value) is as low as ±15%, but the dielectric constant is 30.00.
It will be as low as 0 to 40.000. On the other hand, when manganese oxide (MnO When adding Bi, O, ) or aluminum oxide (AhO+), the dielectric constant and dielectric loss tangent are good, but the capacitance temperature characteristics (T
C value) was insufficient.

Thus, good results for all electrical characteristics (
A semiconductor ceramic material having high dielectric constant and volume resistivity and low dielectric loss tangent and capacitance temperature characteristics (TC value) has not yet been obtained.

As a result of investigating the electrical properties of semiconductor ceramic materials using various materials as valence control aids or sintering aids, the present inventor found that strontium titanate (SrTiO3) and titanium as the main components. Calcium acid (Ca
TiO,), and niobium oxide (NbJ3) or yttrium oxide (YzO3) as an auxiliary agent for valence control.
Silica (St(h), manganese oxide (MnO2), and copper oxide (C) are added as sintering aids.
It has been found that if a mixture with uO) is added, a semiconducting porcelain material with good all electrical properties is obtained.

The present invention was made based on this knowledge, and it is an object of the present invention to provide a semiconductor ceramic material that can obtain good results in all of the above-mentioned electrical properties.

[Means to solve the problem]

The semiconductor ceramic material according to the present invention has a main component of 10 to 80 moles of strontium titanate (SrTi(h) and 3 to 20 moles of calcium titanate (CaTiO+).
With respect to 0 mole, the balance is niobium oxide (NbzO3), yttrioxide (YzO3) (7) one or two of which are 0.1 to 0.4 mole), silica (Stot
) is 0.1 to 0.4 mole, manganese oxide (MnO2) is 0.05 to 0.2 mole, I+/, copper oxide (CuO) is 0
．． or strontium titanate (SrT).
i(h) 97-80 mol, calcium titanate (CaT
iO*) 3 to 20 moles of the main component, the balance is 0.1 to 0.4 mole of one or two of niobium oxide (Nb, O,), yttrium oxide (YzO2), and silica. (SiO2) is 0.1 to 0.4-1-/L/
, manganese oxide (MnO2) is 0.05-0.2-T-
Copper oxide (CuO) is 0.05-0.2-[:/l/
It is characterized in that an insulating composition is diffused into the grain boundaries of the porcelain, which is made up of unavoidable impurities.

[Effect]

When the above-mentioned composition is employed to improve the electrical properties of semiconductor ceramics, the resulting semiconductor ceramic material has sufficiently low dielectric loss tangent and capacitance temperature characteristics (TC value), and has low dielectric constant and volume resistivity. rate will be significantly improved.

〔Example〕

Hereinafter, the present invention will be described in detail with reference to embodiments in which the present invention is applied to, for example, the manufacture of capacitors.

First, the method for manufacturing a semiconductor ceramic material of the present invention will be explained. For example, strontium titanate (SrTi(h)
97 to 80 mol%, calcium titanate (CaTiO) to 100 mol% of the main raw material consisting of 3 to 20 mol%, and one or more of niobium oxide (NbzO3) or yttrium oxide ('bO+) as a valence control auxiliary agent. 2 types from 0.1
In addition, 0.1 to 0.4 mol% of silica (SiO□) and 0.05 to 0.2 mol% of manganese oxide (MnO2) are added as sintering aids. , copper oxide (CuO) was added in each range of 0.05 to 0.2 mol%, and after thorough mixing, a diameter of 10 fi and a thickness of 0.8 m was added.
The material is pressure-molded into a disk-shaped element body of m. After this hydrogen 1-15
%, 1400-1 in an atmosphere consisting of 99-85% nitrogen.
Semiconductor porcelain is manufactured by firing at a temperature of 540° C. for 4 to 10 hours. Next, on one side of the semiconductor porcelain, bismuth oxide (BizOx) and copper oxide (CuO) are applied as a diffusion substance in the form of a slurry at a molar ratio of 9:1 in an amount of 1 mg to 5 mg per semiconductor porcelain. 1-2 at 1350℃
Heat for a period of time to thermally diffuse the diffusing substance. Finally, silver paste is printed on both sides of the semiconductor ceramic material thus obtained and baked at about 800° C. to form silver electrodes, thereby obtaining a capacitor.

Strontium titanate (SrTi03) as the main component
and calcium titanate (CaTiO2), using niobium oxide (NbzO3) as a valence control agent, and using silica (SiO□) and manganese oxide (MnO2) as sintering aids.
Table 1 below shows the electrical properties of semiconductor ceramic materials obtained by mixing copper oxide (CuO) and copper oxide (CuO) in various composition ratios and applying the mixture to semiconductor ceramics. In addition, those marked with * in the rightmost column of the table indicate those whose composition ratios of the mixtures correspond to the conditions of the present invention. Also, the dielectric constant (εapp) in the table
and dielectric loss tangent (tanδ) are values measured at a frequency of 1ktlz and a voltage of 1■, and the capacitance temperature characteristics (
TC value) is based on the capacitance measured at 20℃,
Among the rates of change in capacitance with respect to the reference value measured in the temperature range of -25°C to +85°C, the rates of change at -25°C and +85°C are shown as representative.

On the other hand, the volume resistivity (ρapp) is a value determined from a DC25V 1 minute value.

From Table 1, it can be seen that the composition ratio of the mixture satisfies the conditions of the present invention (marked with * in the figure), that is, strontium titanate (SrTi(h) 97 to 80 mol%, calcium titanate (CaTiO: + ) 3 to 20 mol%, one or two of niobium oxide (NbtO, ), yztrium oxide (yzoi), O91 to 0.4 mol%, silica
ng) is 0.1 to 0.4 mol%, manganese oxide (MnO
2) is 0.05 to 0.2 mol%, copper oxide (CuO) is 0
．． It can be seen that those satisfying the condition of 0.05 to 0.2 mol % have good electrical characteristics.

In other words, strontium titanate (SrTiO2) is
If it is less than mol %, both the capacitance temperature characteristic (TC value) and the dielectric loss tangent show high values, and if it is more than 25 mol %, the dielectric constant decreases and the dielectric loss tangent deteriorates. Also, niobium oxide (N
bzO3) and silica (SiO2) are more than 0.4 mol%, or manganese oxide (MnO□) and copper oxide (
When CuO) is more than 0.2 mol%, the dielectric constant tends to deteriorate significantly, and when niobium oxide (NbzO3) and silica C3iO□) is less than 0.1 mol%, or manganese oxide (MnO□) and copper oxide (CuO) is 0
．． When the amount is less than 0.05 mol %, the TC value is particularly deteriorated.

The example of the present invention has a maximum dielectric constant of about 2.4 times higher than the conventional example indicated by * in Table 1, and in particular, the TC value is ±1% to
Moreover, the dielectric loss tangent is good at 1% or less, and the volume resistivity is improved by 1 to 2 orders of magnitude compared to the conventional one, and the electrical properties are significantly improved.

Figure 1 is a diagram showing the relationship between temperature and capacitance change rate (%). Temperature characteristics (TC
strontium titanate (85 mol% SrTi(h), calcium titanate (
15 mol% of CaTiO,) and 15 mol% of niobium oxide (NbzO3
), silica (Si(h), manganese oxide (MnO2)
A in the figure shows the results of measuring the capacitance temperature characteristics (TC value) of Lt in the temperature range of -25°C to +85°C for those containing 0.2 mol % of copper oxide (CuO) and 0.2 mol% of copper oxide (CuO).
In addition, a mixture having the conventional composition ratio, that is, strontium titanate (SrTiO,) is 100 mol%, niobium oxide (NbzO3) is 0.4 mol%, and manganese oxide (MnO□) is 0.2 mol%. B in the figure shows the results of capacitance temperature characteristics (TC values) similarly measured in the temperature range of -25°C to +85°C for the composition of mol%.
It is shown in As shown in the figure, the product of the present invention shows almost no change in capacitance due to temperature change compared to the conventional product, and can be said to be significantly superior to the conventional product.

The semiconductor ceramic material of the present invention as described above also has the advantage that it can be obtained by a conventional and simple manufacturing process of applying a diffusive substance and firing in the atmosphere.

In the above embodiment, bismuth oxide (BizO2) and copper oxide (C) were used as diffusion substances on one side of the semiconductor ceramic.
Although it was decided to apply a mixture with uO), even if a single substance or a mixture as shown in Table 2 below is applied instead of the mixture, the electrical characteristics will be similar to the above example and the electrical characteristics will be better than the conventional example. improves.

(Margin below) Table 2 Also, in the above-mentioned embodiments, silver paste was printed on both sides of the semiconductor ceramic material and baked to form a silver electrode, but other known electrode materials may also be used. Needless to say. Furthermore, the firing atmosphere during the production of semiconductor porcelain is not limited to an atmosphere consisting of 1 to 15% hydrogen and 99 to 85% nitrogen as in the above-mentioned example, but as long as the atmosphere can sufficiently convert the sample into a semiconductor. Needless to say, other atmospheres are acceptable.

〔effect〕

As detailed above, the semiconductor ceramic material of the present invention contains 97 to 80 mol% of strontium titanate (SrTiO3).
, niobium oxide (N
0.1 to 0.4 mol % of one or two of yztrium oxide (yzoi) or yzoi is added as an auxiliary agent for valence control, and 0.1 to 0.4 mol % of silica (SiO□) is added as a valence control aid.
0.4 mol%, manganese oxide (MnO2) 0.05~
Since 0.2 mol% and 0.05 to 0.2 mol% of copper oxide (CuO) are added as sintering aids, the semiconductor ceramic material has a dielectric constant.

It has good results in electrical properties such as dielectric loss tangent 9 volume resistivity and capacitance temperature characteristics (TC value), and in particular, it is the first in its class with a dielectric constant of 10,000 or more to achieve a TC value of 1% or less. It has a wide range of applications such as capacitors, varistors, and thermistors.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing the relationship between the capacitance change rate and temperature at each temperature based on the capacitance at 20°C.

Claims (2)

[Claims] 1. Strontium titanate (SrTiO_3) 97~
80 mol, calcium titanate (CaTiO_3) 3~
The remainder is niobium oxide (Nb_2O_3) and yttrium oxide (Y_2
0.1 to 0.4 mol of one or two of O_3), 0.1 to 0.4 mol of silica (SiO_2), 0.05 to 0.2 mol of manganese oxide (MnO_2), and copper oxide. (C
A semiconductor ceramic material comprising 0.05 to 0.2 mol of uO) and inevitable impurities. 2. Strontium titanate (SrTiO_3) 97~
80 mol, calcium titanate (CaTiO_3) 3~
The remainder is niobium oxide (Nb_2O_3) and yttrium oxide (Y_2
0.1 to 0.4 mol of one or two of O_3), 0.1 to 0.4 mol of silica (SiO_2), 0.05 to 0.2 mol of manganese oxide (MnO_2), and copper oxide. (C
A semiconductor ceramic material characterized in that an insulating composition is diffused into the grain boundaries of a ceramic containing 0.05 to 0.2 moles of uO) and inevitable impurities.