JPH02101708A - Variable resistor - Google Patents

Abstract

PURPOSE:To let solder rise up to the top part of a board and making a large amount of it adhere at the time of mounting on a printed board so as to make the soldering strong enough by extending a fixed side terminal and a variable side terminal up to at least the lower ends of the side faces along the side faces from the top of the circuit board. CONSTITUTION:For a resin board 1 a variable side terminal 5 and fixed side terminals 6 and 7 are inserted at the time of formation and are fixed integrally. A carbonic resistor 10 provided at the surface of this resin board 1 exhibits nearly circular shape, and both ends are connected electrically to the electrode parts 6a and 7a of the fixed side terminals 6 and 7. The collector electrode part 5a of the variable side terminal 5 is exposed to the opening 1a of the board 1, and a slider 20 is mounted freely in rotation. Each terminal 5-7 extends from the top of the board 1 to the side faces, and further is bent and extends up to the rear, and those are made external connection parts 5b-7b. Accordingly, at the time of surface mounting to a printed board, solder 31 adheres not only to the horizontal part of the external connecting part 5b at the rear of the board but also to the upper part of the vertical part at the side face of the board, and the amount of adhesion increases fairly than before, and to that extent the mounting strength improves.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a variable resistor, and particularly to a semi-fixed variable resistor in which the contacts of a slider are slidable on a resistor provided on the surface of a substrate. .

2. Description of the Related Art Conventionally, as this type of semi-fixed variable resistor, those shown in FIGS. 5 to 10 have been provided.

In this case, the variable side terminal 5 and the fixed side terminals 6, 7 are integrally molded when the resin substrate 1 is molded, and the collector electrode portion 5a of the variable side terminal 5 is connected to the central opening 1a of the resin substrate 1. The electrode portions 6a, 7 of the fixed side terminal 6°7 are exposed to the
a is exposed on the surface of the resin substrate 1. Further, a resistor 10 is provided on the surface of the resin substrate 1 in a substantially arc shape. The resistor 10 is formed by screen printing and baking a carbon-based resistor paste, and both ends thereof are electrically connected to the electrode portions 6a and 7a of the fixed side terminals 6 and 7.

On the other hand, the slider 20 is made of a conductive spring plate material, and has a driver groove 22 formed by cutting and raising a tongue piece 21 in the center part, and a contact part 23 formed in the peripheral part. This slider 20 connects the tongue piece 21 to the collector electrode portion 5 of the variable side terminal 5.
By caulking the opening of a, it is electrically connected and rotatable, and the contact part 23 is connected to the resistor 1.
Press onto 0. In this state, between terminals 5 and 6 and between terminals 5 and 6,
7 are electrically connected, and the resistance value therebetween is variable depending on the rotation angle of the slider 20.

By the way, in the variable resistor with the above configuration,
As shown in FIGS. 7 and 8, the external connection parts 5b, 6b, and 7b of each terminal 5°6.7 exist only on the back side of the board 1, and soldering to the land of the printed circuit board is done only on the surface. It had the problem that it had only one side and its mounting strength was weak.

On the other hand, as shown in FIGS. 8 and 9, the terminal 5°6.7 is pulled out from the middle part of the board 1 and folded from the side surface along the back surface, and bent outward from the lower end of the side surface. Other forms have also been adopted. When these are mounted on the printed circuit board 30, solder 31 is applied to two sides, horizontal and vertical, of the external connection part.
(see FIG. 9), but the fixing strength of the solder 31 is not necessarily sufficient.

Therefore, an object of the present invention is to provide a variable resistor that can be soldered to a land of a printed circuit board with sufficient strength.

Means and Function for Solving the Problems In order to solve the above problems, the variable resistor according to the present invention extends the fixed side terminal and the variable side terminal from the road surface of the board along the side surface to at least the lower end of the side surface. It is characterized by being extended. Each terminal may extend from the side surface of the board to the back surface.

In the above configuration, when mounted on a printed circuit board, the solder roll rises and adheres to the upper part of the vertical surface of each terminal, the amount of adhesion increases considerably, and the mounting strength becomes sufficient.

Inuma Layer In FIGS. 1 to 4, a resin substrate 1 is molded using, for example, diallyl phthalate resin as a main component, and a variable side terminal 5 and fixed side terminals 6, 7 are inserted during molding, and one Fixed to weight. The carbon-based resistor 10 provided on the surface of the resin substrate 1 has a substantially arc shape,
Both ends are electrically connected to electrode portions 6a and 7a of fixed side terminals 6 and 7. Collector electrode portion 5a of variable side terminal 5
is exposed in the opening 1a of the substrate 1, and a slider 20 shown in FIG. 5 is rotatably mounted thereon.

Each terminal 5, 6.7 extends from the top surface of the substrate 1 along the side surface, and is further bent to extend to the back surface, forming an external connection portion 5b, 6b, 7b. Therefore, during surface mounting on the printed circuit board 30 (see FIG. 3),
The solder 31 adheres not only to the horizontal portion of the back surface of the substrate of the external connection portion 5b but also to the top of the vertical portion of the side surface of the substrate, and the amount of solder adhered is considerably increased compared to the conventional case, and the mounting strength is improved accordingly. Of course, although not shown, the state of adhesion of solder to the external connection parts 6b and 7b of the terminals 6 and 7 is also the same as in FIG. 3.

By the way, the resistor 1 provided on the resin substrate 1
0 is generally formed by applying a carbon-based resistance paste onto the substrate 1 by screen printing and then baking it. However, in the conventional printing method, it is necessary to print characteristics such as resistance values on each substrate 1 afterward, which is complicated and inefficient. Furthermore, if there are irregularities on the surface of the substrate 1, the coated resistor 10 will also have irregularities, causing variations in characteristics.

Therefore, in this embodiment, the resistor 10 is formed using a transfer force method. The outline is that carbon-based resistance paste is printed on a heat-resistant film in a predetermined shape, dried, and then baked.
Use as a transfer sheet. Next, the carbon-based resistor 10 formed on this transfer sheet is transferred onto the resin substrate 1. The transfer process includes a method in which the resin substrate 1 is molded in advance, the resistor 10 is adhered to the surface of the resin substrate 1 using an appropriate adhesive, and the sheet is peeled off, and the transfer sheet is placed in a mold together with the terminals 5, 6.7. There is a method in which the sheet is housed in a container, adhered to the surface of the substrate 1 when the sheet is cured after being filled with resin, and then the sheet is peeled off.

Specifically, it is preferable to use a diallyl phthalate resin as a binder resin for the carbon-based resistance paste, and to use a diallyl phthalate resin for the substrate 1 in terms of heat resistance and the like. As the transfer sheet, it is preferable to use a polyimide film in terms of heat resistance, surface smoothness, and the like.

Additionally, a process of chemically treating the heat-resistant film on which the carbon-based resistor is formed may be added to prevent the film from peeling or cracking from the resistor, or the resistor may be pretreated with a silane coupling agent or silicone primer. It is also possible to increase the adhesion between the resistor and the resin substrate and improve the transferability.

Note that the variable resistor according to the present invention is not limited to the above-mentioned embodiments, and can be variously modified within the scope of the gist thereof.

In particular, each terminal 5, 6.7 may be embedded in the surface portion of the substrate 1, and may be drawn out from slightly below the surface portion. Moreover, the external connection part 5b.

6b and 7b do not necessarily have to extend to the back surface of the substrate, but only need to extend to at least the lower end of the side surface of the substrate.

Effects of the Invention As is clear from the above explanation, according to the present invention, since the fixed side terminal and the variable side terminal are extended from the road surface of the board along the side surface to at least the lower end of the side surface, During mounting, the solder rises to the top of the board and adheres in large quantities, making the solder joint strong enough.

[Brief explanation of drawings]

FIG. 1 is a perspective view showing a substrate of a variable resistor according to the present invention;
Figure 2 is a sectional view taken along line A-A in Figure 1, Figure 3 is a sectional view taken along line B-B in Figure 1 showing the state mounted on a printed circuit board, and Figure 4 is the same as in Figure 1 with the resistor removed. It is a perspective view of a state. Figure 5 and subsequent figures show a conventional variable resistor, Figure 5 is a perspective view of the entire variable resistor, Figure 6 is a perspective view of the board from Figure 5 with the slider removed, Figures 7 and Figure 8 is A-A of Figure 6.
9 is a side view of another board mounted on a printed circuit board, and FIG. 10 is a side view of still another board. DESCRIPTION OF SYMBOLS 1... Resin board, 5... Variable side terminal, 5a... Collector electrode part, 5b... External connection part, 6, 7... Fixed side terminal, 6b, 7b... External connection part , 10...
Resistor, 20... Slider, 30... Printed circuit board,
31...Solder. Patent applicant Murata Manufacturing Co., Ltd.

Claims (1)

[Claims] 1. In a variable resistor in which a contact of a slider is slidable on a resistor provided on the surface of a substrate, a fixed side terminal connected to both ends of the resistor and a rotation support part of the slider are connected. A variable resistor characterized in that a variable side terminal extends from a road surface of a substrate along a side surface to at least a lower end of the side surface.