JPS6244485Y2 - - Google Patents

Description

[Detailed Description of the Invention] This invention relates to a variable resistor in which a slider rotates while contacting a resistive film provided on a substrate, and particularly to a means for attaching a terminal to the resistive film.

In conventional variable resistors, the terminals are attached to the resistive film by means as shown in FIG. In the figure, 1 is a substrate made of an insulating material such as alumina, 2 is a resistive film provided on this substrate 1, and an electrode 3 made of silver or the like is provided at the end of the resistive film 2 so as to overlap with the resistive film 2. Board 1
A hole 4 is also provided.

Next, the tip 6 of the terminal 5 made of a metal plate is attached to the substrate 1.
Insert it into hole 4 from the bottom and bend the top end,
This tip 6 is bonded onto the electrode 3 with solder 7,
After that, the solder flux is washed away.

Conventional variable resistors such as those described above require a large number of man-hours to attach terminals, making mass production difficult. Furthermore, even when an automatic soldering machine is used, it is difficult to control the amount of solder, and potato solder occurs, making it difficult to homogenize the soldering state.

Furthermore, the silver electrodes formed on the substrate are absorbed by the solder due to the heat of the molten solder at high temperature, which is known as the silver eating phenomenon, causing poor contact between the terminal and the resistive film, making poor conduction more likely to occur. In addition, the use of an organic solvent such as trichlene as a cleaning solution is undesirable from the standpoint of environmental hygiene, and there are also other problems such as the need for additional solder costs.

This idea was made to solve the problems of conventional variable resistors as mentioned above, and it is a variable resistor that allows the terminals to be easily attached to the electrodes on the board without using solder. The purpose is to provide.

The configuration of this device is to provide a resistive film on the substrate with which the contact piece of the slider comes into contact, a hole that penetrates the electrode film and the substrate at the end of this resistive film, and a hole that extends from the electrode film to the inner surface of this hole. In a configuration in which an electrode layer is formed and a shaft-shaped portion provided on a separate metal terminal is press-fitted into the hole, a pressing force acts only in one direction between the hole and the shaft-shaped portion, and a pressing force acts in the other direction. The shape and dimensions of the hole and the shaft-like part are set so that no solder is required, and the board is not cracked by the pressure during press-fitting.

Embodiments of this invention will be described below with reference to FIGS. 2 to 9 of the accompanying drawings.

In the figure, 11 is a substrate made of an insulating material such as alumina, and a semicircular arc-shaped resistive film 1 is placed on this substrate.
2 is formed, and an electrode film 13 made of silver or the like is provided on both ends of the resistive film 12 so as to overlap with the resistive film 12. However, this electrode film 13 may be an extension of the resistive film 12 as it is, or may be a combination of the resistive film 12 and a resistive film having a lower resistance value.

A hole 14 penetrating the substrate 11 is provided in the electrode film 13, and an electrode layer 15 made of the same material as the electrode film 13 is provided on a part or the entire surface of the inner surface of the hole 14. Formed simultaneously during printing.

Reference numeral 16 denotes a terminal made of a metal plate, and a shaft-like portion 17 made of metal is integrally provided on this terminal 16. This shaft-shaped part 17 may be formed into a hollow shape with a closed upper end as shown in FIGS. 4 and 5 by drawing process, or may be formed into a tubular shape with an open upper end, but in both cases, the upper end is It is tapered so that it can easily enter the hole 14.

In addition, the hole 14 is shaped like a long hole such as a rectangle or an ellipse in the example shown in FIG. 4 and FIG. The hole 14 has a square cross section or a circular cross section as shown in FIG.
Letting the diameter of the shaft-shaped portion be d, the relationship l>d>s holds.

In the case of FIG. 7, the hole 14 is a round hole and the shaft-shaped portion 17 has a rectangular cross section. In this case, the diameter of the hole is d ₁ ,
If the major axis of the shaft-shaped portion 17 is l ₁ and the minor axis s ₁ , then l ₁ > d ₁
>s ₁ relationship.

In the case of FIG. 8, both the hole 14 and the shaft-like part 17 are rectangular, and the long axis of the hole 14 is l ₂ , the short axis is s ₂ , the long axis of the shaft part is D ₂ , and the short axis is d ₂ Then, l ₂ > d ₂ s ₂ < D ₂ .

With the hole 14 and the shaft portion 17 having the dimensions and shapes as described above, when the shaft portion 17 is press-fitted into the hole 14, on the short diameter side of the hole 14, as shown in FIG.
The shaft-shaped portion 17 having a larger diameter than this is strongly pressed against both sides of the hole 14 and is deformed, expanding toward the longer diameter side of the hole 14.

Therefore, when the shaft-shaped portion 17 is completely fitted into the hole 14, the short diameter side of the hole 14 is completely inserted into the hole 14 as shown in FIG.
That is, the layer 15 on the inner surface of the hole 14 and the shaft-like part 17 are in strong contact with each other, and the shaft-like part 1 is flat on the long diameter side.
A slight gap remains between 7 and hole 14.

In the case of the examples shown in FIGS. 6, 7, and 8, the side that is in a press-fit relationship is the layer 15 on the inner surface of the hole 14 and the shaft-shaped portion 17.
There is a slight gap between the layer 15 and the shaft portion 17 on the side that is not press-fitted.

9 shows an example of press-fitting the shaft portion 17 into the hole 14 of the substrate 11.
1 is placed upside down on a pedestal 18, and the electrode 16 is pressed with a pressing member 19 to press fit the shaft-like part 17 into the hole 14. In this way, the head of the shaft-like part 17 is It is crushed to be flush with the surface of the substrate 11, and the adhesion between the shaft portion 17 and the hole 14 is increased. This figure shows the side where a gap remains even after press-fitting, and it goes without saying that the shaft-shaped portion 17 and the layer 15 are in close contact with each other in a cross section perpendicular to this cross section.

In addition, if the surface of the pedestal 18 corresponding to the hole 14 is recessed or formed into a hole, please refer to Figures 4 and 5.
As shown in the figure, the upper end of the shaft-shaped portion 17 protrudes above the substrate 11.

Incidentally, a relatively soft metal such as brass, soft iron, red bronze, etc. is suitable for the material of the shaft-shaped portion 17.

In addition, 20 in the figure is a metal rotary slider whose center is rotatably attached to the substrate 11 by a caulking pin 21, and a contact piece 22 formed on a part of the slider 20 is attached to the resistive film. 12.

Since this invention has the above configuration, it has the following effects.

Unlike conventional variable resistors, there is no need for soldering, so various processes associated with soldering can be saved, and the cost required for soldering is eliminated, and automatic assembly using hoops is extremely easy, resulting in a significant reduction in equipment costs. can.

Further, there is no possibility of defects caused by soldering such as silver eating due to soldering or shorts between terminals due to solder horns.

In particular, in the case of this invention, when the shaft-like part is press-fitted into the hole, a pressing force is applied only in one direction, and in other directions, no pressing force is applied at all because a gap remains between the shaft-like part and the hole. Therefore, since the pressing force is concentrated in one direction, the bonding strength in this direction is increased, and even when a rotational moment is applied to the terminal, the strength against it is increased. Furthermore, since a gap is created between the hole and the shaft in the - direction, even if there is variation in the dimensions of the hole and the shaft, the error is absorbed by the gap and This has the effect of preventing the substrate from cracking by preventing the application of large pressure.

[Brief explanation of the drawing]

FIG. 1 is a partial cross-sectional view of a conventional variable resistor. Fig. 2 is a sectional view of the variable resistor of this invention, Fig. 3 is a partially cutaway plan view of the same as above, Fig. 4 is an enlarged sectional view of the terminal mounting part of the same as above, and Fig. 5 is Fig. 4 A-A. 6, 7, and 8 are partially cutaway exploded perspective views showing each embodiment of the terminal mounting portion, and FIG. 9 is an enlarged sectional view of the shaft portion in a press-fitted state. 11...Substrate, 12...Resistive film, 13, 15...
... Electrode film, 14 ... Hole, 16 ... Metal terminal, 17
...Axial part.

Claims (1)

[Claims for Utility Model Registration] (1) A resistive film that the contact piece of the slider comes into contact with is provided on the substrate, a hole is provided that penetrates the electrode film at the end of this resistive film and the substrate, and the inner surface of this hole is In a configuration in which an electrode layer is formed next to the electrode film, and a shaft-shaped portion provided on a separate metal terminal is press-fitted into the hole, the pressing force acts only in one direction between the hole and the shaft-shaped portion, and the pressure force acts in the other direction. A variable resistor characterized in that the shape and dimensions of the hole and shaft-like part are set so that there is a gap in the direction and press force does not work. (2) Registration of a utility model characterized in that the hole formed in the substrate is shaped like a long hole with a long axis and a short axis, and the diameter of the shaft-shaped part of the metal terminal is shorter than the long axis of the hole and longer than the short axis. A variable resistor according to claim 1. (3) The shank of the metal terminal has a flat cross-sectional shape consisting of a major axis and a minor axis, and the diameter of the hole in the board into which this shank is press-fitted is smaller than the major axis of the shank and larger than the minor axis. A variable resistor according to claim 1, characterized in that it is a utility model.