JP2003324006A - Resistor and ceramic fixed resistor unit - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a resistor which is restrained from varying in resistance value and a ceramic fixed resistor unit. <P>SOLUTION: A conductive material (SnO<SB>2</SB>Sb<SB>2</SB>O<SB>3</SB>) and talc, calcium compound, barium compound (e.g. talc CaCO<SB>3</SB>BaCO<SB>3</SB>) as insulating ceramics are mixed into an SnO<SB>2</SB>-Sb<SB>2</SB>O<SB>3</SB>resistor composition, and then a steatite porcelain as an insulating aggregate is added to the resistor composition for the formation of a mixed material. The mixed material is sintered at a prescribed temperature (1245 to 1360°C) into the resistor. The resistance change rate ΔR of the resistor for an applied voltage can be improved. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a resistor and a ceramic fixed resistor.

[0002]

_2. Description of the Related Art Conventionally, SnO ₂ --Sb ₂ has been used as a resistor.
A ceramic fixed resistor using an O ₃ -based metal oxide conductive material is known. This type of resistor utilizes the semiconducting property of SnO ₂ —Sb ₂ O ₃ based metal oxide as its conduction mechanism. Further, since it is difficult to sinter with the conductive substance as it is, the raw material of the steatite porcelain (hereinafter, also referred to as insulating ceramics) is added and sintered, and the resistance value is adjusted.

Since such a resistor is a solid resistor sintered at a high temperature, it has a feature that it can be used even at a high temperature without fear of disconnection and has a large heat capacity, a small size, and an impact voltage. Also strong. In addition, it has advantages such as excellent chemical erosion resistance and weather resistance (for example, good heat resistance and moisture resistance) and low cost.

[0004]

However, since the above-mentioned conventional resistor has a low rate of change ΔR of the resistance value with respect to the applied voltage of 0.70 or less, the resistance value decreases when a high voltage is applied. There is. In other words, there is a problem that the voltage coefficient of the resistor is deteriorated by applying the voltage.

The present invention has been made in view of the above problems, and an object of the present invention is to provide a resistor and a ceramic fixed resistor capable of suppressing a change in resistance value even when a high voltage is applied. It is to be.

Another object of the present invention is to provide a reliable and inexpensive resistor and ceramic fixed resistor.

[0007]

As one means for achieving the above object and solving the above-mentioned problems, for example, the following structure is provided. That is, a mixture of a conductive material composed of tin oxide (SnO ₂ ) and antimony oxide (Sb ₂ O ₃ ) and an insulating ceramic composed of talc / calcium compound / barium compound (talc / Ca compound / Ba compound) is mixed. 0.001 to 1 as an insulator aggregate for the material
It is characterized in that it is obtained by firing a composition containing 19 parts by weight of steatite porcelain at 1245 ° C to 1360 ° C.

For example, if the above steatite porcelain is used,
The composition added at 30 to 30 parts by weight at 1245 ° C to 13 ° C.
It is characterized by being baked at 60 ° C.

Further, for example, a composition obtained by adding 31 to 119 parts by weight of the above steatite-based porcelain is prepared at 1245 ° C.
It is characterized by being fired at a temperature of from 1318 ° C to 1318 ° C.

For example, the above-mentioned mixed material is 10 wt% to 5%.
0 wt% tin oxide, 0.01 wt% to 10 wt%
Of antimony oxide and 40 wt% to 85 wt% of insulating ceramics are blended in a composition of 100 wt% in total.

For example, the insulating ceramics are
wt% to 86 wt% talc, 9 wt% to 14 w
It is characterized in that t% barium compound and 5 wt% to 10 wt% calcium compound are blended in a composition of 100 wt% in total.

Further, as another means for solving the above problems, the following structure is provided. That is, the resistor according to any one of the above inventions is used for the ceramic fixed resistor.

[0013]

BEST MODE FOR CARRYING OUT THE INVENTION A resistor according to an embodiment of the present invention will be described in detail below with reference to the accompanying drawings and tables. First, the general relationship between the electric field strength and the resistance value of the resistor will be described. 1A is a graph showing the relationship between the electric field strength and the resistance value in the resistor, and FIG. 1B is a diagram for explaining the length of the resistor.

It can be seen from FIG. 1A that the rate of change in resistance value tends to decrease as the electric field strength (indicated by voltage V with respect to the length L of the resistor) decreases. Therefore, if the voltage is kept constant and the resistor is lengthened as shown in (b), the electric field strength decreases, and the rate of change of the resistance value with respect to the applied voltage ΔR (when a high voltage pulse is applied to the resistor for a short time). It is considered that the rate of change in the resistance value of 1) can be improved.

However, even if the longitudinal dimension of the resistor is simply lengthened, it imposes restrictions on the actual mounting shape of the resistor, so that it cannot be lengthened unnecessarily.

Therefore, in the present invention, tin oxide (Sn
O ₂ ) -antimony oxide (Sb ₂ O ₃ ) -based resistor composition was added according to the conditions described below, focusing on the fact that the addition of an insulator aggregate is effective in improving the rate of change ΔR of the resistance value. Also, various tests and prototypes were performed.

The manufacturing conditions and manufacturing steps of the resistor according to this embodiment will be described in detail below. As a means for improving ΔR, it is first necessary to select an insulator aggregate to be added to the resistor composition.

The conditions required for the insulator aggregate are (1)
The material has a small capacitance and a small change in resistance value in a high frequency range, and a material having a small relative permittivity in order to meet these requirements. (2) The insulating aggregate is a resistor composition. Two things are called for not to react.

In this embodiment, several kinds of insulator aggregates satisfying these conditions are used for optimization. Table 1 shows the substance names selected as the insulating aggregate satisfying the above conditions,
The relative dielectric constant is shown. In addition, Table 2 shows the results of determining whether or not these selected substances can be used as aggregates.

[0020]

[Table 1]

[0021]

[Table 2]

Here, in order to confirm the reactivity between the insulator aggregate and the resistor composition, each of the selected substances is mixed with the insulator, and the mixture is fired at a predetermined temperature to form a resistor. The suitability of the substance as an aggregate was judged based on the case of "no lumber".

Specifically, these substances are used as 200 and 5
The particles are sized using a 0 mesh sieve and the powder particle size is 75 to 30.
Aligned to 0 μm. In order to confirm reactivity, these insulator aggregates and resistor compositions are mixed and pulverized under the conditions described below,
After molding, in air atmosphere, 1240 ° C to 1360
Baked at ° C.

The composition ratio of the resistor composition is such that the conductive material is SnO ₂ : 33.95 wt% and Sb ₂ O ₃ : 1.05w.
t%, the insulating ceramics (65 wt%) are talc: 81.0 wt%, BaCO ₃ : 14.0 wt%,
CaCO ₃ : It has a composition of 5.0 wt%. here,
Ba and Ca are not limited to carbonates, and may be oxides, acetates, oxalates, chlorides, and the like.

As a result of confirmation of the reactivity between the insulator aggregate and the resistor composition, as shown in Table 2, for the substances other than the steatite-based porcelain among the selected substances, the physical properties and the sintering were determined. There was a problem in terms of sex and electrical performance.

That is, a resistor using a fused alumina-based material, a zirconia-based material, a zircon sand-based material, or a silica-based material as an insulator aggregate is not sintered or is deformed by expansion or cracking. Therefore, it was found that it is not suitable for use. Moreover, all the ones fired at 1240 ° C. or lower were unsintered, and all the ones fired at a temperature higher than 1360 ° C. melted or deformed. The sinterability was judged from the water absorption rate and the shrinkage rate.

Therefore, the steatite porcelain having the same performance as in the case of "without aggregate" satisfies the above-mentioned conditions as an insulator aggregate and is effective as an aggregate added to the resistor composition. I got the conclusion.

FIG. 2 is a flow chart showing steps of manufacturing the resistor according to the present embodiment. Step S in FIG.
In 11, conductive material (hereinafter abbreviated as SC as appropriate)
And insulating ceramics (hereinafter appropriately abbreviated as IC) are blended so as to have the composition described below, and to them, an insulator aggregate (the above-mentioned steatite porcelain)
In the ratio described below (0 to 120 parts by weight (where 0 is
(Corresponding to the conventional example)) and weigh the total weight to 100 g.

Regarding the conductive substance (SC) and the insulating ceramics (IC), as shown in Table 3, Table 4, Table 5 and Table 6, SC is SnO ₂ .Sb ₂ O ₃ and IC
Is talc / CaCO ₃ / BaCO ₃ .

The composition ratio of these is tin oxide: 22.25.
~ 33.95 wt%, antimony oxide: 0.75-3.
85 wt%, insulating ceramics: 65-75 wt%
Then, the composition is such that the total of these is 100 wt%. Insulating ceramics are talc: 81-86 wt
%, Barium carbonate: 9-14 wt%, calcium carbonate:
The composition is 5 to 10 wt% and the total is 100 wt%. Here, barium Ba and calcium Ca
Are not limited to carbonates, and may be, for example, oxides, acetates, oxalates, chlorides and the like.

In the next step S12, the raw materials are mixed using a ball mill. Specifically, using zirconia balls as a mixing medium and pure water as a mixing solvent, the composition weighed in step S11 is wet ball mill mixed for a certain period of time in a mixing pot.

In step S13, the materials mixed by the ball mill are mixed and slurry dried in an oven in which hot air is circulated. In the following step S14, the dried piece obtained in step S13 is meshed (for example, 100
Coarsely pulverize with a mesh sieve). At this time, zirconia balls are used as the grinding media.

In step S15, the binder is dropped onto the finished powder, mixed, and sized (granulated) with a mesh (for example, 100 mesh screen). As the binder, for example, an aqueous solution of polyvinyl alcohol + propylene glycol is used.

In the next step S17, a constant pressure is applied to the granulated material for molding. Here, for example, uniaxial pressure molding is performed to obtain a cylindrical molded product having a predetermined size. In the following step S19, the molded product is fired in an air atmosphere. In this embodiment, the firing temperature is set to 124.
The temperature is set to 0 ° C. to 1360 ° C., and after reaching these temperatures at a constant heating rate, the temperature is held for a certain time.

In step S20, for example, a silver paste is applied to the end surface of the resistor obtained by the above firing, dried, and then baked at a constant temperature. Then, finally, in step S21, the manufactured resistor is evaluated. The evaluation here is, in addition to the appearance observation, calculation of the resistance value and the rate of change (ΔR) of the resistance value with respect to the applied voltage,
Also, the sinterability (based on shrinkage and water absorption) is confirmed.

Talc contained in the insulating ceramic mixture, which is the resistor composition, causes the following reaction at around 850 ° C.

[0037] _{3MgO · 4SiO 2 · H 2 O} → 3 (MgO · SiO 2) + SiO 2 + H 2 O ↑ ... (1)

In this reaction, steatite porcelain (3
(MgO · SiO ₂ )) and SiO ₂ are generated, but Si
O ₂ reacts with barium carbonate (BaCO ₃ ) and calcium carbonate (CaCO ₃ ) to produce a Ba / Ca-based silicate compound (glass).

ΔR was measured using the high voltage impulse circuit shown in FIG. First, a test sample (resistor) in the silicon oil bath 43 from the electrostatic discharge simulator 41.
20 kV high-voltage impulse for 45
The voltage is applied once, and the resistance value is calculated from the current voltage value measured by the digital oscilloscope 42 via the current probe 46 and the high voltage probe 47. Then, the voltage-resistance value characteristic is obtained from this calculation result, and the resistance value at 10 kV is 5 kV.
ΔR was calculated by dividing by the resistance value at that time.

For example, sample No. 4 (1260 ° C
The ΔR of the baked product) was calculated as follows. That is, the resistance value when the applied voltage is 10 kV = 4.10 k
Since the resistance value when Ω is 5 kV = 4.60 kΩ, ΔR = 4.10 / 4.60 = 0.891≈0.89 (2)

[0041]

[Table 3]

[0042]

[Table 4]

[0043]

[Table 5]

[0044]

[Table 6]

As shown in Table 3, Table 4, Table 5, and Table 6, for example, 10 to 110 parts by weight of steatite-based porcelain aggregate is added to the SnO ₂ —Sb ₂ O ₃ -based resistor composition. Then, it can be seen that ΔR is improved as compared with the conventional product. It should be noted that ΔR, which has an improved value compared to the conventional values, includes Tables 3, 4 and
In Table 5 and Table 6, the mark * is attached. Also,
In Table 3, Table 4, Table 5, and Table 6, the units of the numerical values of SC composition and IC blending ratio are all [wt%].

The improvement in ΔR is due to SnO ₂ —Sb ₂ O ₃
This is because the addition of a steatite porcelain as an insulator aggregate to the system resistor composition results in a zigzag structure in which the conductive material is bent around the insulator aggregate. As a result, ΔR can be obtained without changing the outer diameter of the resistor.
Can be improved.

FIG. 3 schematically shows the difference in the formation state of the conductive path corresponding to the case where the ΔR is high and the case where the ΔR is low. In the figure, (a) corresponds to low ΔR, and (b) corresponds to high ΔR, the black circles are insulator aggregates (steatite porcelain), and the substances existing between them (Fig. The white part in is the conductive material. An example of the conductive path is indicated by an arrow that goes straight or an arrow that bends and runs.

On the other hand, in the regions where the addition amount of the steatite porcelain aggregate was 0 parts by weight and 120 parts by weight, ΔR was not improved, and the result was equivalent to the conventional case.

Further, ΔR varies depending on the firing temperature, and in the present embodiment, the steatite porcelain aggregate is 10 to 10 times.
The composition added with 30 parts by weight is, for example, 1260 to 13
The ΔR was improved when fired at 60 ° C. and when the composition containing 60 to 110 parts by weight of the aggregate was fired at 1260 to 1300 ° C., for example.

Regardless of the amount of the aggregate added, all compositions burned at 1240 ° C. (or lower) and 120 parts by weight of the aggregate added and fired at 1260 ° C. or lower. No. was unsintered. Also, 13
The one fired at a temperature higher than 60 ° C. was melted or deformed, so that ΔR could not be measured.

These tendencies were the same confirmed events in all the composition systems in which the tests (production of resistors) were conducted. Therefore, it was confirmed that even if the composition of the SnO ₂ —Sb ₂ O ₃ -based resistor composition was changed, ΔR was improved if the amount of aggregate added and the firing temperature were optimal.

As described above, according to this embodiment.
Then, the conductive material (SnO₂・ Sb₂O ₃) And an insulating ceramic
Mixture of talc, calcium compound, barium
SnO formed by mixing compounds₂-Sb₂O₃System resistor composition
In contrast, steatite porcelain as an insulator aggregate
The added mixed material should be sintered at a predetermined temperature to form a resistor.
And the change in resistance value with respect to the applied voltage of the obtained resistor
The rate ΔR can be improved.

Further, according to the present embodiment, even if the composition of the conductive material and the insulating ceramics is changed, if the amount of aggregate added and the firing temperature are optimum, the resistance value with respect to the applied voltage of the resistor is changed. The rate of change ΔR can be improved.

The composition ratio of the conductive material (SC) and the insulating ceramics (IC) in the above-mentioned embodiment, the addition amount of the steatite porcelain aggregate to the resistor composition,
Also, the firing temperature is only an example, and the object of the present invention can be achieved even when the composition and the like are in the following ranges.

That is, the mixed material is tin oxide: 10 to 50
wt%, antimony oxide: 0.01-10 wt%, insulating ceramics: 40-85 wt% total 100 wt
%, And a composition obtained by adding 0.001 to 119 parts by weight of the steatite porcelain aggregate to this mixed material (SnO ₂ —Sb ₂ O ₃ -based resistor composition) at 1245 ° C.
Bake at 1360 ° C.

More preferably, the composition containing 10 to 30 parts by weight of the steatite porcelain aggregate is added at 1245 ° C.
A composition obtained by firing at 1360 ° C. and adding 31 to 119 parts by weight of the steatite-based porcelain aggregate at 1245 ° C.
Bake at 1318 ° C.

[0057]

As described above, according to the present invention,
Even if a high voltage is applied, it is possible to suppress changes in the resistance value of the resistor.

Further, according to the present invention, a highly reliable and inexpensive resistor and a resistor using the same can be obtained.

[Brief description of drawings]

FIG. 1 is a diagram for explaining a general relationship between an electric field strength and a resistance value in a resistor.

FIG. 2 is a flow chart showing a manufacturing process of a resistor according to an exemplary embodiment of the present invention.

FIG. 3 is a diagram schematically showing a difference in a formation state of a conductive path corresponding to a case where ΔR is high and a case where ΔR is low.

FIG. 4 is a diagram showing a high voltage impulse circuit for measuring ΔR.

[Explanation of symbols]

41 Electrostatic Discharge Simulator 42 Digital Oscilloscope 43 Silicon Oil Bath 45 test sample 46 Current probe 47 High voltage probe

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Isao Tonouchi             3672 Ina, Ina, Ina City, Nagano Prefecture             Inside the company (72) Inventor Takashi Sukegawa             3672 Ina, Ina, Ina City, Nagano Prefecture             Inside the company F-term (reference) 5E033 AA17 AA25 BB03 BC01 BD01

Claims (6)

[Claims] 1. An insulating ceramic composed of talc / calcium compound / barium compound (talc / Ca compound / Ba compound) is added to a conductive material composed of tin oxide (SnO ₂ ) and antimony oxide (Sb ₂ O ₃ ). The composition obtained by adding 0.001 to 119 parts by weight of steatite porcelain as an insulating aggregate to the added mixture is
A resistor characterized by being fired at 5 ° C to 1360 ° C. 2. The steatite-based porcelain article of 10 to 3
The composition added with 0 parts by weight is from 1245 ° C to 1360 ° C.
The resistor according to claim 1, wherein the resistor is fired. 3. The steatite-based porcelain article 31 to 1
The composition added with 19 parts by weight is treated at 1245 ° C to 1318
The resistor according to claim 1, wherein the resistor is fired at a temperature of ° C. 4. The mixed material is 10 wt% to 50 wt%.
% Of tin oxide, 0.01 wt% to 10 wt% of antimony oxide, and 40 wt% to 85 wt% of insulating ceramics are compounded in a composition of 100 wt% in total. The resistor according to any one. 5. The insulating ceramics is 81 wt%
5. The resistor according to claim 4, wherein talc of from 86 wt% to 86 wt%, a barium compound of 9 wt% to 14 wt%, and a calcium compound of 5 wt% to 10 wt% are mixed in a composition of 100 wt% in total. 6. A ceramic fixed resistor using the resistor according to any one of claims 1 to 5.