JPH0770376B2 - Method of manufacturing resistance substrate for variable resistor - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial field of application) The present invention relates to a small and thin type used in consumer electronic devices such as video, headphone stereo, car stereo, and television, which are becoming smaller, lighter, and more multifunctional. The present invention relates to a method of manufacturing a resistance base body including terminals and resistance elements for forming the variable resistor.

(Prior Art) Conventionally, a resistive substrate of this type is disclosed in, for example, Japanese Patent Laid-Open No. 58-46604.
As described in Japanese Patent Publication No. JP-A-2003-264, it is common to have a structure as shown in FIG. That is, the drawn portion 21a of the female terminal 21 formed by drawing and punching a metal plate is used as the current collecting film portion 24 at both ends of the resistance film 23 formed on the insulating substrate 22 such as a phenol resin laminated plate. It was fixed by passing through the through hole 25 provided and opening the tip of the drawing processed portion 21a of the female terminal and crimping by compression. In addition,
FIG. 7 shows a state in which the female terminal 21 is fixed to the insulating substrate 22.

Also, when configuring as a variable resistor, the caulking may loosen due to heat during soldering, and the stability of electrical contact tends to be impaired. Thus, insert molding is often performed when resin-molding the housing of the variable resistor. (Example of insert molding: JP-A-60-6860
(See Japanese Patent Laid-Open No. 1) (Problems to be Solved by the Invention) In such a conventional configuration, since the female terminals are drawn, there is a limit to the processing, and small terminals cannot be formed. Further, in order to sufficiently withstand cracking due to caulking when mounting the terminal, a large area such as the distance between the end of the insulating substrate and the terminal mounting hole is required. Furthermore, since the terminals are caulked and attached, the height of the caulked portion increases the thickness of the variable resistor. As described above, there is a limit to the construction of small and thin type variable resistors.

It is an object of the present invention to provide a method of manufacturing a resistance base for making a variable resistor smaller and thinner.

(Means for Solving Problems) In order to solve the above problems, the present invention forms a resistive film on the surface of a flexible thin insulator such as a resin film by a method such as printing or vapor deposition, Small through-holes are provided at both ends of each. On the back surface side of the insulator on which the resistance film is formed, one end closes each through hole, the other end projects from the edge of the insulator, and at least covers almost the entire back side of the pattern of the resistance film and contacts with each other. The terminal plates made of a pair of metal plates that are not turned on are stacked. In that state, insert resin molding is performed so that the resistance film, the through hole, and the peripheral portion thereof are exposed. As a result, the insulating resin on which the resistance film is formed and the terminal plate are mechanically fixed by the molding resin that also serves as the housing.

Next, a conductive coating material is applied to the exposed through hole and its peripheral portion and dried to electrically connect the resistance film and the terminal plate. At this time, the conductive coating material is mainly composed of a resin component and a conductive material, and it is preferable to use a conductive coating material in which the conductive material shows a tendency to settle in the resin component.

(Operation) The operation of this technical means is as follows. That is, the mechanical fixing between the terminal plate and the resistance film is performed by the molding resin, and the electrical connection between the terminal plate and the resistance film is performed by the conductive paint.

Therefore, the terminal plate and the insulator can be microfabricated, do not require a large area to withstand crimping, and do not crimp, so that the thickness is reduced.

As a result, it is possible to supply the resistance substrate for forming the small and thin variable resistors.

(Example) Hereinafter, an example will be described in detail with reference to the accompanying drawings. FIG. 1 shows an embodiment of the present invention, in which 1 is a terminal plate, 2 is an insulator, 3 is a resistance film, 4 is a conductive paint, 5 is a housing made of molding resin, and 6 is a housing molding. Sometimes the hole of the mark of the pin which supports the terminal board, 7 is the central boss portion of the housing.

Next, a specific configuration and manufacturing method of each part of the above embodiment will be described. FIG. 2 is a plan view showing an insulator having a resistance film formed thereon, 2 is an insulator such as a resin film, 3 is a resistance film formed by printing on the surface of the insulator, and 10a and 10b.
Is a through hole, 11 is a positioning through hole, 12 is a small central through hole,
14 is a blank part for forming the insulator into a required shape.

FIG. 3 is a plan view of the terminal board 1, showing a positioning through hole.
Have 13. The terminal board 1 is made by punching a metal plate,
Alternatively, it is a flat plate that has been subjected to etching processing, and the surface thereof is covered with a substance such as silver or solder that has good electrical conductivity and can be soldered.

FIG. 4 shows a state in which the terminal plate 1 shown in FIG. 3 is superposed on the back surface of the insulator 2 shown in FIG. Through hole
10a and 10b are closed at one end of the terminal board 1, and the back side of the portion where the resistance film 3 is formed is covered with the terminal board 1 so as to cover substantially the entire back side of the pattern of the resistance film and prevent them from coming into contact with each other. And support it as extensively as possible. The terminal plate portions protruding from the edges of the insulator 2 are kept at a distance such that they do not contact each other. In this state, the position is regulated using the positioning through holes 11 and 13, and insert resin molding is performed.

FIG. 5 shows a state after insert resin molding.
Sliding parts and through holes 10a, 10b as variable resistance of the resistance film 3
The peripheral portions 8a, 8b and other central boss portions 7 are exposed without being covered with resin. The surface of the terminal board 1 is exposed through the through holes 10a and 10b. Here, the terminal plate 1 and the insulator 2 are fixed to each other by a housing 5 formed by insert resin molding. The shape of the housing (including the shape of the exposed portion) is determined by the insert resin molding die.

Next, a conductive coating material is applied to the inside of the through holes 10a, 10b and the peripheral portions 8a, 8b and dried to electrically connect the resistance film 3 and the terminal board 1.

Also, in FIG. 5, 16a and 16b are arbitrary terminal board cutting positions, and 17a and 17b are arbitrary insulator cutting positions. At the time of completion as a variable resistor, the terminal board and the insulator are as described above. Cut in position.

The central boss portion 7 of the housing shown in FIG. 1 and FIG.
Has the effect of strengthening against the bending force of the housing, but is due to the design of the variable resistor or the resistance substrate, and is not always necessary.

Further, with respect to heat generated when the resistance film is energized, disposing a terminal plate made of a metal plate on the back surface of the insulator on which the resistance film is formed has an effect of improving heat dissipation.

(Effects of the Invention) As described above, according to the present invention, it is possible to manufacture the resistance base body for forming the small and thin variable resistors by a simple method without caulking. Further, it has a high heat dissipation effect and can prevent distortion and deformation during insert molding, which is practically useful.

[Brief description of drawings]

FIG. 1 is a sectional view of a resistance substrate in one embodiment of the present invention, FIG. 2 is a plan view of an insulator having a resistance film formed thereon, FIG. 3 is a plan view of a terminal plate, and FIG. FIG. 5 is a plan view showing a state in which the insulator and the terminal plate are superposed, FIG. 5 is a plan view showing a state after the housing is molded, FIG. 6 is a perspective view showing a conventional terminal fixing method, and FIG. It is sectional drawing which shows the conventional terminal fixed state. 1 ... Terminal board, 2 ... Insulator, 3 ... Resistive film, 4 ...
Conductive paint, 5 ... Enclosure, 8a, 8b ... Peripheral area of through hole, 10
a, 10b ... Through hole.

Claims (1)

[Claims] 1. A resistance film having a predetermined pattern on the surface and a back surface of a film-like insulator having through holes at both ends of the pattern of the resistance film, one end of each of which closes the through hole,
With the other end protruding from the edge of the insulator, covering at least substantially the entire back side of the pattern of the resistance film, and stacking the terminal plates made of a pair of metal plates provided so as not to contact each other. A step of performing insert resin molding so as to expose the resistive film on the surface side of the insulator, the through hole and its peripheral portion, and applying the conductive paint to the through hole and its peripheral portion to form the resistive film. And a step of electrically connecting the terminal plate to the variable resistor.