JP3168809B2 - Resistor composition and semi-fixed resistor using the same - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a composition for obtaining a resistor film with small sliding noise and a semi-fixed resistor obtained by using the same.

[0002]

2. Description of the Related Art There are two types of resistors: fixed resistors having a fixed resistance value and variable resistors capable of changing the resistance value within a certain range. A variable resistor is a device that moves a terminal called a slider on a resistive film and adjusts it to a desired resistance value. Once the adjustment is completed, it is used in a place where there is almost no operation. Are especially called semi-fixed resistors. Therefore, the condition of the sliding test of the semi-fixed resistor is lighter than that of the variable resistor.

[0003] A semi-fixed resistor is generally provided with an electrode and a resistive film on an insulating substrate, and is provided with a slider which rotates on contact with the resistive film. Two types, a resin type and a ruthenium oxide-glass type, are mainly used. The carbon-resin system is inexpensive but easily deteriorates at high temperatures, and the ruthenium oxide-glass system is expensive, but has the advantage of high reliability and is used properly depending on the application.

[0004] In recent years, semi-fixed resistors using a ruthenium oxide-glass based resistive film have also been directed to small-sized ones that can be surface-mounted. However, several problems to be solved have arisen for the miniaturization. One of them is sliding noise.

[0005] Stainless steel is often used as a slider for ruthenium oxide-glass based resistive films. Since the resistance film of this system has a large amount of sliding noise due to the mixture of glass with a single contact, noise has been reduced by using a plurality of sliders or by using a plurality of contacts with a single slider. . However, in the case of miniaturization, the number of contacts is limited to one and the number of contacts is limited to two. According to such a slider, since the sliding noise is inevitably increased, improvement of the resistance film itself has been demanded.

[0006]

In order to reduce sliding noise, it is conceivable to reduce the amount of glass to be added. However, it is difficult to secure a necessary resistance value, and disadvantages such as increased wear due to sliding of the resistive film. There is.

An object of the present invention is to provide a composition for a resistor capable of reducing sliding noise without sacrificing wear of a resistive film, and a semi-fixed resistor using the same.

[0008]

In order to achieve the above object, the composition of the present invention comprises a ruthenium oxide powder and / or a pyrochlore-type ruthenium oxide powder as a conductive component.
And 0 parts by weight, and the alumina powder 3-15 parts by weight, 15 to 40 wt% of PbO, the SiO ₂ 20 to 50 wt%, Ca
O 15 to 30 wt% and Al ₂ O ₃ 7 to 20 wt%
PbO containing and totaling 85% by weight or more
The -SiO ₂ -CaO-Al ₂ O ₃ glass powder 10-50
Parts by weight and 10 to 65 parts by weight of glass powder mainly composed of PbO having a softening point of 400 to 650 ° C., and these ruthenium oxide powder, alumina powder, PbO—SiO ₂ —CaO
Total 95 The -al ₂ O ₃ glass powder and PbO glass powder
It is characterized in that it is contained so as to be 100 parts by weight.

Further, the semi-fixed resistor of the present invention is characterized in that a resistive film made of the above composition is provided on a fire-resistant insulating substrate, and a slider which rotates in contact with the resistive film and a rotating mechanism therefor are provided. There are features.

[0010]

The ruthenium oxide-glass resistor composition is fired at 750-950 ° C. to form a resistor film. It is considered that if the conductive component can be collected on the film surface during the firing, the chance of contact between the slider and the conductive component increases, and noise can be reduced. According to commonly used glass powder, when the glass softens during the firing process, the conductive particles are wrapped in the glass, and the film surface tends to be vitreous. The use of glass with a high softening point or the addition of refractory oxide powder makes it difficult for the conductive particles to be enveloped in the glass and facilitates distribution on the film surface. Wears out.

The inventor of the present invention has proposed a combination of alumina powder, glass which reacts with the alumina during sintering and crystallizes, and glass having a relatively low softening point, so that the sliding of the resistive film is not sacrificed. The inventors have found that dynamic noise can be effectively reduced, and arrived at the present invention. According to the composition of the present invention, crystals are precipitated during the firing process, so that the glass and the substrate adhere to each other, and a resistive film resistant to abrasion is obtained. This crystal deposition prevents the conductive component from being enveloped in the glass.

As the conductive component, a commonly used ruthenium oxide (RuO ₂ ) powder and / or pyrochlore-type ruthenium oxide (typically, Pb ₂ Ru ₂ O _{6 + x} ) powder is suitable. The resistance value can achieve 10 Ω to 10 MΩ in sheet resistance depending on the particle size and content of the conductive component. Generally, when the particle size is several tens nm, and 10 to 40 parts by weight in 100 parts by weight of the total solid content of the composition. good. Alumina powders with a submicron to several micron particle size are suitable.
When the amount is less than 15 parts by weight, crystal precipitation becomes insufficient, and when the amount exceeds 15 parts by weight, the film strength becomes weak.

The glass which reacts with alumina is Pb
O 15 to 40 wt%, a SiO ₂ 20 to 50 wt%,
The CaO 15 to 30 wt% and the Al ₂ O ₃ comprises 7-20 wt%, and the total amount of these used _{PbO-SiO 2 -CaO-Al 2} O 3 glass is 85 wt% or more. If PbO is less than 15% by weight, the softening point becomes too high, and if it exceeds 40% by weight, it becomes difficult to crystallize. If the content of SiO ₂ is less than 20% by weight, it is difficult to crystallize, and if it exceeds 50% by weight, the softening point becomes too high.

CaO must be contained in an amount of 15% by weight or more to effectively react this glass with alumina, but if it exceeds 30% by weight, vitrification becomes difficult. Al ₂ O ₃ in the glass promotes crystallization, but its effect is small at less than 7% by weight, and vitrification becomes difficult at more than 20% by weight. B ₂ O ₃ , ZnO, Ti
Components generally contained in glass, such as O and ZrO ₂ , may be added as long as they are added in an amount of 15% by weight or less. Such a glass powder is required in an amount of 10 to 50 parts by weight based on 100 parts by weight of the total solid content of the composition. If the addition is less than 10 parts by weight, the effect is small, and if it exceeds 50 parts by weight, it becomes relatively more than the low softening point glass described below, and it becomes difficult to form a resistance film.

The above PbO-SiO ₂ -CaO-Al ₂ O
It is difficult to provide flexibility suitable for forming a resistive film using only ₃ glasses, and it is necessary to use a glass having a softening point of 400 to 650 ° C. and containing PbO as a main component. 45 to 75 wt% of PbO as such glass, the SiO ₂ 5 to 4
A glass containing 0% by weight and the balance being Al ₂ O ₃ , B ₂ O ₃ , ZnO or the like is suitable. If the PbO glass is less than 10 parts by weight in 100 parts by weight of the total solid content of the composition, it is difficult to form a resistive film, and if it exceeds 65 parts by weight, the effect of reducing sliding noise decreases. Each glass has an average particle size of 0.5 to 5
μm is appropriate, and preferably 0.8 to 3 μm.

Ruthenium oxide powder, alumina powder, PbO
-SiO ₂ -CaO-Al ₂ O ₃ glass powder and PbO glass powder may if 95 parts by weight or more in the total solid content 100 parts by weight. The remaining additives of 5 parts by weight or less are used to adjust the temperature coefficient of resistance, and include Mn, Nb, Sb, Ti, Fe, and C.
oxide of u.

The solid content is kneaded with an organic vehicle in a three-roll mill or the like to form a paste composition. The vehicle is prepared by dissolving a binder resin such as ethyl cellulose or nitrocellulose in a solvent such as terpineol or butyl carbitol acetate (concentration: 5 to 20% by weight).
Often use. Solids and vehicle are combined at solids 1
10 to 100 parts by weight of the vehicle is sufficient for 00 parts by weight, but 25 to 65 parts by weight is a more preferable ratio.

The paste-like resistor composition is printed and applied in a desired pattern so as to straddle an electrode of a conductor composition previously formed on a refractory insulating substrate such as a ceramic,
Heating at 100-300 ° C for several minutes to evaporate the solvent,
Next, a peak temperature of 750 to 950 ° C. and a peak temperature of 5-1
By firing in a belt-type furnace for about one hour in a total firing cycle set at 0 minutes, a resistive film is formed. A semi-fixed resistor can be obtained by attaching the slider and its rotating mechanism to the substrate on which the electrodes and the resistive film are formed.

The sliding noise of a semi-fixed resistor is JIS
It can be measured by the constant current method (method B) described in C 5261, paragraphs 5 and 8. The slider is generally made of stainless steel and the slider 1
The book is provided with one or two contacts as protrusions. When the slider is slid from one end of the resistive film to the other end and returns to the original end, the sliding noise is measured as a voltage. The largest noise voltage value during this period is divided by the applied DC current value to convert it to a resistance value, and the ratio (%) to the total resistance value between the electrodes is the sliding noise of the resistor. . Each time the sliding operation is performed, the sliding noise tends to increase.

Further, the total resistance value changes due to wear of the resistive film due to sliding. Comparing the resistance values before and after 100 reciprocations after the start of the sliding operation, it can be said that the ratio is good if the ratio is ± 1% or less.

[0021]

EXAMPLE Ruthenium oxide (RuO) having a particle diameter of several tens of nm was used.
₂ ) Powder and / or lead ruthenate compound (Pb ₂ Ru ₂₎
O _{6 + x} ) powder, alumina powder having an average particle diameter of 2 μm, glasses A1 to A4 shown in Table 1, and B1 to B5 shown in Table 2.
And Nb ₂ O ₅ and MnO ₂ were used as additives to obtain 14 kinds of mixtures at the ratios shown in Table 3. These mixtures 1
35 parts by weight of a terpineol solution of ethyl cellulose as a vehicle was added to 00 parts by weight, and the mixture was kneaded with a three-roll mill to obtain uniform paste-like compositions.

The composition for the resistor is formed on an alumina substrate provided with an electrode of an Ag conductor containing 1% by weight of Pb on an alumina substrate having an outer circle radius of 3 m.
m, printed in a horseshoe-shaped resistance pattern having an inner circle radius of 2 mm, fired in a belt furnace having a peak temperature of 850 ° C. to form a resistance film, and subjected to a sliding test.

The sliding test is based on JIS C 5261 Nos. 5 and 8.
In accordance with the constant current method (method B) described in the item of the term “sliding noise”, the stainless steel two-contact slider is slid 100 times on the resistive film to calculate the 100th reciprocating sliding noise.
Measure the total resistance value of the resistive film before and after the sliding test,
The rate of change in resistance due to sliding was calculated. The results are summarized in Table 3.

In Table 3, Experiment No. No. 5 shows that the film strength was weakened due to too much alumina powder. 6 is glass A
It was shown that the running noise was not improved due to insufficient CaO in the test. In the case of No. 7, the ratio of glass A was too small and the noise reduction was a step forward. In No. 11, the ratio of glass A was too large, and the film strength was weak. Experiment No.
In the case of No. 13, when the softening point of glass B was too low, the glass leached out of the pattern to cause dripping. Conversely, No. 14 indicates that the softening point is too high, the film strength is weakened and the film is easily worn.

[0025]

According to the composition for a resistor of the present invention, it is possible to obtain a resistive film having a small sliding noise and a small change in the resistance value due to abrasion. This has greatly contributed to practical application.

[0026]

[Table 1]

[0027]

[Table 2]

[0028]

[Table 3]

Claims (2)

(57) [Claims] 1. The method according to claim 1, wherein the conductive component is ruthenium oxide powder and / or
Alternatively, pyrochlore-type ruthenium oxide powder is 10 to 40 parts by weight, alumina powder is 3 to 15 parts by weight, and PbO is 15 parts by weight.
40 wt%, a SiO ₂ 20 to 50 wt%, CaO hints 15-30 wt% and the Al ₂ O ₃ 7 to 20 wt% and the total amount of these is 85 wt% or more PbO-S
10 to 50 parts by weight of iO ₂ —CaO—Al ₂ O ₃ glass powder and 10 to 65 parts by weight of glass powder mainly composed of PbO having a softening point of 400 to 650 ° C. powder, PbO-SiO ₂ -CaO-A
l ₂ O ₃ glass powder and PbO glass powder in total 95 to 10
A composition for a resistor, which is contained in an amount of 0 parts by weight. 2. Ruthenium oxide powder and / or
Alternatively, pyrochlore-type ruthenium oxide powder is 10 to 40 parts by weight, alumina powder is 3 to 15 parts by weight, and PbO is 15 parts by weight.
40 wt%, a SiO ₂ 20 to 50 wt%, CaO hints 15-30 wt% and the Al ₂ O ₃ 7 to 20 wt% and the total amount of these is 85 wt% or more PbO-S
10 to 50 parts by weight of iO ₂ —CaO—Al ₂ O ₃ glass powder and 10 to 65 parts by weight of glass powder mainly composed of PbO having a softening point of 400 to 650 ° C. These ruthenium oxide powder, alumina powder, PbO-SiO ₂ -CaO-A
l ₂ O ₃ glass powder and PbO glass powder in total 95 to 10
A resistance film made of a composition for a resistor contained so as to be 0 parts by weight is provided on a fire-resistant insulating substrate, and a slider that rotates on contact with the resistance film and a rotation mechanism thereof are provided. Semi-fixed resistor.