JPH10270220A - Variable resistor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To restrain a board from increasing in temperature, even if Joule heating is generated in a resistor by a method, wherein the board is formed of composite material composed of resin-molding material and filler of metal compound powder mixed in a specific weight ratio. SOLUTION: A board 21 is equipped with a horseshoe resistor 22 of carbon or the like, provided with a hole 23 located nearly at its center, and integrally formed with a middle terminal 24 and an outer terminal 25 by insert molding. At this point, a base board, formed of polyphenylene sulfide which contains 10 to 90 wt.% of filler of metal compound and glass is used as the board 21. A protrudent part 27 is provided as protruding towards the hollow 23 of the board 21, a through-hole 28 is provided to the protrudent part 27 nearly at the center, a slider 29 which slides on the resistor 22 located on the upside of the board 21 is provided, and a metal driver plate provided with a cutout in parallel with the board 21 is provided.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a variable resistor mainly used for circuit adjustment of electronic equipment.

[0002]

2. Description of the Related Art A conventional variable resistor is disclosed in JP-A-7-222.
No. 15 is known.

A conventional variable resistor will be described below with reference to the drawings. FIG. 6 is a side sectional view of a conventional variable resistor, and FIG. 7 is a top view showing a state in which a middle terminal and an outer terminal are integrally formed by insert molding on a substrate which is the main part.

In FIGS. 6 and 7, reference numeral 1 denotes a horseshoe-shaped resistor 2 made of carbon or the like on the upper surface, a hollow hole 3 provided substantially in the center, and a middle terminal 4 and an outer terminal 5 integrally provided. It is a substrate. This substrate 1 is made of polyfernin sulfide (hereinafter referred to as “PPS”) 60% and glass 4
It is composed of 0% mixed material and has a thermal conductivity of 0.24.
W / m · K. Reference numeral 6 denotes a metal driver plate having a protruding portion 7 protruding toward the hollow hole 3 of the substrate 1, and a through hole 8 provided substantially in the center of the protruding portion 7. The driver plate 6 is mounted on the substrate 1.
A notch 10 is provided which has a slider 9 which slides on the upper surface of the resistor 2 and which is parallel to the substrate 1. The middle terminal 4
Has one end pivotally connected to and electrically connected to the through hole 8 of the driver plate 6 and the other end provided from the bottom surface to the side surface of the substrate 1. One end of the external terminal 5 is electrically connected to the resistor 2 and the other end is provided from the side surface to the bottom surface of the substrate 1.

A state in which the conventional variable resistor configured as described above is mounted on a circuit board and used will be described with reference to the drawings. FIG. 8 is a side sectional view showing a state where a conventional variable resistor is mounted on a circuit board 11.

Here, suppose that the external terminal 5 of the conventional variable resistor is
A load of 0.1 W (for example, 1
A current of 10 mA is applied by applying 0V. ), The temperature of the resistor 2 rises due to Joule heat. The thermal conductivity of the substrate 1 is 0.24 W / m · K, and the temperature rise of the substrate 1 due to Joule heat generated in the resistor 2 is about 67 ° C. as shown in FIG.

[0007]

However, in the above-mentioned conventional configuration, since the temperature rise of the substrate 1 is about 67.degree. C., the change in the resistance of the resistor is about-.
15%, which causes a problem that the characteristics of the variable resistor are deteriorated.

An object of the present invention is to solve the above-mentioned conventional problems, and an object of the present invention is to provide a variable resistor in which the temperature of the substrate 1 hardly rises even when Joule heat is generated in the resistor. .

[0009]

In order to achieve the above object, a variable resistor according to the present invention is characterized in that the material of the substrate is a resin molding material containing 10% by weight or more of a powder filler made of a metal compound.
It is configured to contain less than 10% by weight.

According to this configuration, it is possible to obtain a variable resistor in which the thermal conductivity of the substrate itself is increased and the temperature of the resistor hardly rises.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The invention according to claim 1 of the present invention is characterized in that a center terminal of this resistor is placed on a horseshoe-shaped resistor provided on a substrate on which a middle terminal and an outer terminal are integrally formed by insert molding. In a variable resistor in which a slider of a rotatable driver plate is slid with a part as a fulcrum, a powder filler made of a metal compound is added to a resin molding material as the substrate.
Since it contains 0% by weight or more and 90% by weight or less,
This has the effect of reducing the change in resistance during energization.

The invention according to a second aspect of the present invention has a horseshoe-shaped resistor on the upper surface, and the middle terminal and the outer terminal are integrally formed by insert molding, and the filler of the metal compound is contained in an amount of 10% by weight or more and 90% or more. A substrate made of a resin molding material containing not more than 5% by weight, and a slider having a through hole substantially at the center of a protrusion protruding toward the hollow hole of the substrate and sliding on a resistor on the upper surface of the substrate. And a driver plate provided with a notch parallel to the substrate, so that a change in resistance value during energization is small.

According to a third aspect of the present invention, in accordance with the first or second aspect, the substrate has a thermal conductivity of 0.1.
Since it is 3 W / m · K or more, it has an effect that a change in resistance value during energization is small.

According to a fourth aspect of the present invention, in the first or the second aspect of the present invention, since the filler of the substrate is any one of a metal oxide, a metal nitride, and a metal boride, This has the effect that the change in the resistance value at the time is small.

(Embodiment) A variable resistor according to an embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a side sectional view of a variable resistor according to an embodiment of the present invention, and FIG. 2 is a top view showing a state in which a middle terminal and an outer terminal are integrally formed on a substrate of the variable resistor which is the main part. It is.

In FIG. 1 and FIG. 2, reference numeral 21 denotes a substrate having a horseshoe-shaped resistor 22 made of carbon or the like on the upper surface and having a hollow hole 23 provided substantially in the center, and having a middle terminal 24 and an outer terminal 25 inserted therein. It is integrally formed by molding. Here, as the substrate 21, a base plate made of PPS and glass containing a filler of a metal compound in a range of 10% by weight to 90% by weight is used. Reference numeral 26 designates a protruding portion 27 protruding toward the hollow hole 23 of the substrate 21, has a through hole 28 substantially at the center of the protruding portion 27, and slides on the resistor 22 on the upper surface of the substrate 21. This is a metal driver plate having a moving slider 29 and a cutout 30 parallel to the substrate 21. The middle terminal 24 has a terminal portion 31 extending from the bottom surface to the side surface of the substrate 21 and the driver plate 26.
Pivot portion 32 pivotally connected to and electrically connected to the through hole 28
Is provided. The external terminal 25 is electrically connected to the resistor 22 at one end, and the other end has a tip portion 33 provided from the bottom surface to the side surface of the substrate 21.
The middle terminal 24 and the outer terminal 25 are formed integrally with the substrate 21 and the terminal portion 31 and the tip 3
3 is exposed from the bottom surface portion 34 of the substrate 21 and bent upward along the side surface portion 35 of the substrate 21.

The assembling method of the variable resistor configured as described above according to an embodiment of the present invention will be described below with reference to the drawings.

The terminal portion 31 and the tip portion 33 of the middle terminal 24 and the outer terminal 25 are formed integrally with the substrate 21 so as to be exposed from the bottom surface portion 34. The resistor 22 made of carbon or the like is applied on the upper surface of the substrate 21 in a horseshoe shape so as to be electrically connected to the external terminal 25 whose one end is exposed. Next, the terminal portions 3 of the middle terminal 24 and the outer terminal 25
1. The tip portion 33 is bent upward along the side surface portion 35 of the substrate 21.

Next, the pivot portion 32 provided on the middle terminal 24 is connected to the through hole 2 of the driver plate 26.
8, the driver plate 26 is rotatably supported on the substrate 21 by caulking the distal end of the pivot portion 32. At this time, the driver plate 2
The slider 29 of No. 6 is disposed on the upper surface of the substrate 21 at a position in contact with the resistor 22.

The variable resistor constructed and assembled as described above according to one embodiment of the present invention is mounted on a circuit board 36 as shown in FIG.

Here, the substrate 21 is made of a metal oxide powder such as MgO or Al ₂ O ₃ , a metal nitride such as Si ₃ N _4, a metal nitride such as ZrB ₂ , TiB ₂ or the like. Metal boride, metal carbide such as SiC is used, and PP
It was contained in the mixture ratio of S and glass fiber as shown in (Table 1).

[0022]

[Table 1]

FIG. 4 shows the thermal conductivity of the substrate and the value of 0.1 to the resistor.
FIG. 5 is a characteristic diagram showing the relationship between the temperature rise of the resistor when W is applied, and FIG. 5 is a diagram showing the relationship between the temperature rise of the resistor and a decrease in the resistance value of the resistor.

Here, when the substrate 21 of the variable resistor according to the embodiment of the present invention is the material 1 shown in Table 1, a load of 0.1 W is applied to the external terminal 32 (for example, a resistor having a total resistance of 1 kΩ). When 10 V is applied to the substrate 21 and a current of 10 mA is applied.), Since the filling material of the substrate 21 is 10% by weight of MgO, the thermal conductivity is as high as 0.32 W / m · K. Joule heat generated in the resistor 22 is
Heat is dissipated from the circuit board 36 from 1 through the middle terminal 24 and the outer terminal 25. Therefore, as shown in FIG. 4 and (Table 1), the temperature of the resistor 22 rises by about 58 ° C. due to Joule heat. That is, as shown in FIG. 5, the reduction rate of the resistance value of the resistor 22 is about 7%, which has an effect of reducing the change in the resistance value.

In the variable resistor according to the embodiment of the present invention, the substrate 21 is a base plate made of PPS and glass containing 10% by weight of a filler of a metal compound of MgO (Table 1). As shown in Documents 2 and 3 of the above, the filling material of the metal compound of MgO is
Even if it is 0% by weight, it has the same effect.

In the variable resistor according to one embodiment of the present invention, the metal oxide such as MgO is used as a filling material for the molding material. Metal oxides such as ₂ O ₃ , metal nitrides such as Si ₃ N ₄ , metal borides such as ZrB ₂ and TiB ₂ , or Si
Even a metal carbide such as C has the same effect.

However, if the content of the filler exceeds 90% by weight, the moldability of the substrate 21 deteriorates, which is not preferable. On the other hand, if the filling material is less than 10% by weight, the thermal conductivity is so small that the rise in temperature cannot be kept small.

[0028]

As described above, according to the present invention, the thermal conductivity of the substrate is increased by forming the substrate with a resin molding material containing 10% by weight to 90% by weight of a filler made of a metal compound. Joule heat generated from the resistor is easily transmitted from the board to the circuit board through the outer and middle terminals and radiated easily, so the temperature rise of the resistor is reduced and the resistance change during energization is improved. A resistor can be provided.

[Brief description of the drawings]

FIG. 1 is a side sectional view of a variable resistor according to an embodiment of the present invention.

FIG. 2 is a top view of a substrate on which a middle terminal and an outer terminal of the variable resistor, which are main parts, are integrally formed.

FIG. 3 is a side sectional view showing a state where the variable resistor is mounted on a printed circuit board.

FIG. 4 is a characteristic diagram showing a relationship between the thermal conductivity of the substrate and the temperature rise of the resistor when 0.1 W is applied.

FIG. 5 is a characteristic diagram showing a relationship between a rise in the temperature of the resistor and a decrease in the resistance value of the resistor.

FIG. 6 is a side sectional view of a conventional variable resistor.

FIG. 7 is a top view showing a state in which a middle terminal and an outer terminal are integrally formed on a substrate of a conventional variable resistor which is a main part of the same.

FIG. 8 is a side sectional view showing a state where the conventional variable resistor is mounted on a printed circuit board.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 21 Substrate 22 Resistor 23 Hollow hole 24 Middle terminal 25 Outer terminal 26 Driver plate 27 Projecting part 28 Through hole 29 Slider 30 Notch 31 Terminal part 32 Joint part

Claims (4)

[Claims] 1. A slider of a driver plate rotatable around a center of the resistor on a horseshoe-shaped resistor provided on a substrate integrally having a middle terminal and an outer terminal. In the variable resistor, the substrate may be formed by adding a filler of a metal compound to a resin molding material in an amount of 10% by weight to 90% by weight.
A variable resistor characterized by containing not more than weight%. 2. A filler of a metal compound having a horseshoe-shaped resistor on the upper surface, a middle terminal and an outer terminal being integrally formed, and having a hollow hole substantially at the center, is contained in an amount of 10% by weight or more.
A substrate made of a resin molding material containing 0% by weight or less, and a slider having a through hole substantially at the center of a projecting portion projecting toward the hollow hole of the substrate and sliding on a resistor on the upper surface of the substrate. And a driver plate having a notch parallel to the substrate. 3. The variable resistor according to claim 1, wherein the substrate has a thermal conductivity of 0.3 W / m · K or more. 4. The variable resistor according to claim 1, wherein the filler of the substrate is one of a metal oxide, a metal nitride, and a metal boride.