JPH08236319A - Resistance paste - Google Patents

Abstract

PURPOSE: To obtain a resistance body for variable resistors which has a low slide contact resistance by dispersing a small amount of one kind of noble metal particles or mixture of kinds of particles in a resistance paste. CONSTITUTION: A resistance paste is composed of a thermosetting synthetic resin soln. mixed with kinds of conductive agents and non-conductive fillers dispersed therein. As one kind of the conductive agent, it contains noble metal particles of 0.1-3.0μm in mean grain size. The synthetic resin of the paste is selected from among diallylisophthalate resin, aromatic denatured phenol resin, phenol resol resin and phenol novolak resin. This reduces the contact pressure to the resistance body of a slider to reduce the wear depth of the resistance body, whereby a long-slide-life resistance body can be obtained.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a resistance paste, and more particularly to a resistance paste forming a resistor of a variable resistor.

[0002]

2. Description of the Related Art A conventional example will be described with reference to the drawings. The resistance paste used for the variable resistor is phenol resin dissolved in a high boiling alcohol solvent, acetylene black on epoxy resin and other thermosetting synthetic resins, graphite and other conductive agents and dialuminum trioxide, silicon dioxide, It is manufactured by kneading dichromium trioxide and a non-conductive filler such as fluororesin.

Here, this resistance paste is usually mixed in a ratio of about 1 part of a mixture of a conductive resin and a non-conductive filler to 2 parts of a synthetic resin solution. The paste formed by kneading these is printed on a glass epoxy substrate or a ceramic substrate into a predetermined shape by screen printing, and this is heated and cured by a belt conveyor type or batch type heat curing furnace to form a resistor. Manufactured. A variable resistor is formed by a metal slider slidingly contacting the resistor. The variable resistor is required to be inexpensive and have a low sliding contact resistance.

[0004]

The variable resistor described above uses a phenol resin as a thermosetting synthetic resin of a synthetic resin solution, and an average particle diameter of 0.01 as a conductive agent.
consisting of acetylene black of μm or more and 0.05 μm or less and a resistance paste containing graphite having an average particle size of 0.7 μm or more and 6.0 μm or less, and phosphor bronze for spring or beryllium copper alloy If the slider and the slider are combined, the manufacturing cost can be reduced.

A slider using phosphor bronze or beryllium copper alloy for springs has a problem that a metal oxide is generated on the surface thereof and contact resistance between the resistor and the slider is increased. It is a thing. This problem has been solved by setting the contact pressure of the slider to the resistor high. However, doing so increases the wear depth of the resistor due to the sliding of the slider, and Sliding life will be shortened. This problem can be solved by plating the slider with a noble metal, but it becomes expensive.

The present invention solves the above problems by forming a resistance paste for a variable resistor having a low sliding contact resistance.

[0007]

Means for Solving the Problems In a resistance paste obtained by mixing and dispersing a plurality of kinds of conductive agents and non-conductive fillers in a thermosetting synthetic resin solution, one kind of conductive agent has an average particle diameter of 0.1 μm or more. A resistance paste was prepared by mixing and blending noble metal fine particles of 3.0 μm or less. Then, the mixing ratio of the noble metal fine particles is 3 wt% or more and 30 wt% of the total conductive agent.
% To be less than or equal to the resistance paste.

Further, the thermosetting synthetic resin constitutes a resistance paste which is one kind selected from diallyl isophthalate resin, aromatic modified phenol resin, phenol resole resin and phenol novolac resin.

[0009]

Embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a diagram for explaining the manufacturing process of the resistance paste of the present invention. In the resistance paste of the present invention, the thermosetting synthetic resin solution 1 is mixed with a high boiling alcohol solvent in an amount of 50
What melt | dissolved wt% -60 wt% thermosetting synthetic resin is used. As the thermosetting synthetic resin, when any one selected from diallyl isophthalate resin, aromatic modified phenol resin, phenol resole resin, and phenol novolac resin is used, an electromechanically suitable variable resistor resistor is used. Can be configured.

As the conductive agent, noble metal fine particles 2 having an average particle size of 0.1 μm or more and 3.0 μm or less are contained in an amount of 3 wt% of the total conductive agent.
Used within the range of 30 wt% or less. Here, the precious metal fine particles are any one of Au, Ag, and Pt.
A kind or a mixture of plural kinds of fine particles is adopted. The reason why the addition amount of the noble metal fine particles 2 is limited in this way is that if the amount is less than 3 wt%, the contact resistance is hardly improved,
This is because the resistance value as the resistor is reduced when the value exceeds, which is inconvenient for forming a resistor having a desired resistance value. And the reason for limiting the average particle size in this way is
Precious metal fine particles of less than 0.1 μm are expensive because the market volume is small, and if it exceeds 3.0 μm, the film surface of the resistor becomes rough and unsuitable for the film surface of the resistor of the variable resistor. is there. As another conductive agent for the noble metal particles 2, acetylene black 3 and graphite 4 are used.

As the non-conductive filler 5, 1 to 3 predetermined amounts of dialuminum trioxide, dichromium trioxide, silicon dioxide and Teflon resin are weighed and used. The thermosetting synthetic resin solution 1, the precious metal fine particles 2, the acetylene black 3, the conductive agent comprising the graphite 4 and the non-conductive filler 5 are supplied to the crusher 6 and premixed therein, and then in the roll mill 7. Mix and grind. After mixing and pulverizing in the roll mill 7, the desired resistance paste 8 is formed.

Resistor paste 8 thus formed
Is screen-printed on the insulating substrate 9 and heat-cured at 200 ° C. for 7 minutes in the heat-curing furnace to form the resistor 10.
Can be configured. Reference numeral 11 is a terminal connected to the resistor 10. 2 to 5, a resistor variable resistor formed using the resistor paste of the present invention will be compared with a conventional resistor variable resistor.

As an example of the variable resistor of the resistor formed by using the resistance paste of the present invention, the average particle diameter is 2.0 μm.
A variable resistor configured by combining a resistor formed by using a resistance paste formed by mixing silver fine particles of m with 10 wt% of the total conductive agent and a phosphor bronze slider for spring without silver plating. use. Further, as examples of conventional variable resistors of conventional resistors, conventional example 1 in which a conventional resistor and a phosphor bronze slider for spring without silver plating are combined, and a conventional resistor and silver plating are applied. Conventional Example 2 in which a phosphor bronze slider for a spring is combined is used.

FIG. 2 shows the increased price per product produced by mixing fine silver particles in the resistance paste according to the present invention, and the product produced per silver plating of the phosphor bronze slider for spring. It is the graph which compared with the increase price. The increase price per product when the resistance paste contains fine silver particles is 2-3 yen, while the increase price per product when the slider is silver plated is 1 yen. , The price difference is large.

FIG. 3 is a graph showing changes in the number of times the variable resistor slides and the contact resistance value. It shows that the same good sliding contact resistance as the initial value is maintained even after the number of sliding times of 500,000 times. 3 with reference to FIG.
A method of measuring the contact resistance value of will be described. Variable resistor V
Against _R, between the through the fixed terminal 1 and the contact point 2 supplies a constant current of 1mA from the constant current source A, an oscilloscope and other voltage monitoring device O _S a fixed terminal 1 and the constant current source A The connection is made, the voltage is measured, and the contact resistance value at the contact point 2 is calculated.

FIG. 5 is a graph showing the number of sliding times of the variable resistor and the wear depth of the resistor due to the slider. The wear depth of the resistor is larger than that of the conventional example of the variable resistor. It shows that it was possible to reduce. In the above-mentioned embodiment, the slider which is not plated with the noble metal is used, but when the slider which is plated with the precious metal is used, the slider is compared with the conventional variable resistor product. Even if the contact pressure between the resistor and the resistor is lowered, the sliding contact resistance can be reduced, so that the wear depth of the resistor is reduced and the sliding life is further improved.

[0017]

According to the present invention, by sliding a small amount of a mixture of one or more kinds of fine particles of Au, Ag and Pt as noble metal fine particles in the resistance paste, the sliding contact resistance can be improved. A low variable resistor resistor can be constructed. Further, since the contact pressure of the slider with respect to the resistor can be made smaller than in the conventional example, the wear depth of the resistor can be reduced and a resistor for a variable resistor having a long sliding life can be constructed. it can.

[Brief description of drawings]

FIG. 1 is a diagram illustrating a manufacturing process of a resistance paste of the present invention.

FIG. 2 is a diagram comparing the increased price per product produced by blending silver fine particles.

FIG. 3 is a diagram for comparing the relationship between the sliding frequency of a variable resistor and a contact resistance value.

FIG. 4 is a diagram illustrating a method of measuring a contact resistance value in FIG.

FIG. 5 is a diagram comparing the relationship between the sliding frequency of the variable resistor and the wear depth of the resistor due to the slider.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI Technical display location H01B 1/24 H01B 1/24 A (72) Inventor Hiroshi Ando 2-268 Sobudai, Zama City, Kanagawa Prefecture Tokyo Metropolitan Cosmos Electric Co., Ltd.Kanagawa factory

Claims (3)

[Claims] 1. A resistance paste obtained by mixing and dispersing a plurality of types of conductive agents and non-conductive fillers in a thermosetting synthetic resin solution, wherein the average particle diameter of 0.1 μm is used as one type of conductive agent.
A resistance paste comprising noble metal fine particles of 3.0 μm or less mixed and mixed. 2. The resistance paste according to claim 1, wherein the mixing ratio of the noble metal particles is 3 wt% of the total conductive agent.
% To 30 wt% or less, a resistance paste. 3. The resistance paste according to claim 1, wherein the thermosetting synthetic resin is diallyl isophthalate resin, aromatic modified phenol resin,
A resistance paste which is one of a phenol resole resin and a phenol novolac resin.