JPH0222801A - Sealed type variable resistor - Google Patents

Abstract

PURPOSE:To prevent the production of burrs and to prevent the penetration of moisture from the outside of a product by printing a silicone elastic material in a ring shape on the outer periphery of a resistor on an insulating substrate. CONSTITUTION:A ruthenium resistor 2 is formed into a circular arc shape on the top face of an insulating substrate 1, and silver or palladium first conductors 3a, 3b and second conductor 3c are printed and baked so as to be connected with both ends of the resistor 2. A silicone elastic material 4a is printed in a ring shape on the outer periphery of the resistor 2 and dried. Copper lead terminals 5a-5c are connected to the conductors 3a-3c by means of solder or the like. The resistor element having the lead terminals 5a-5c connected thereto is put in a mold for insert molding. The mold for insert molding is pressed against a part of the resistor 2 and a part of the conductors 3a-3b for exposing said parts of the resistor 2 and the conductors 3a-3b. Since the silicone elastic material 4a provided on the outer periphery of the resistor 2 is also pressed and compressed by the mold during this process, the synthetic resin material is prevented from producing burrs extended toward the resistor 2 during the insert molding process.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a sealed variable resistor, and particularly to a sealed structure of a resistor element.

[Conventional technology]

Conventionally, the resistor element of this type of sealed variable resistor has an arc-shaped resistor 2 on the upper surface of an insulating substrate 1, as shown in FIG.
and conductors 3a, 3b, 3c are printed and fired, and then lead terminals 5a, 5 are attached to the conductors 3a, 3b, 3c, respectively.
b and 5c were connected using means such as soldering.

[Problem to be solved by the invention]

In the conventional sealed variable resistor described above, the lead terminal 5a
, 5b, 5c are connected to each other, and the insulating substrate 1 is then packaged with a synthetic resin material in the next step, so it is housed in a mold. At this time, the resistor 2 and the conductor 3a.

Resistor 2 and conductor 3a so that parts 3b and 3c are exposed.
, 3b, and 3c are pressed together with a mold, but a gap is created between the resistor 2 and the insulating substrate 1 due to the thickness of the resistor 2, and when molding the outer case, a synthetic resin with low melt viscosity, for example, is used. When epoxy resin is used as the outer case material, there is a drawback that particles are generated from the gap between the insulating substrate 1 and the resistor 2.

In addition, synthetic resins with high melt viscosity, such as PP5 (poly
If resin (phenylene sulfide) is used, the adhesion with the insulating substrate 1 is poor, so there is also the drawback that moisture from outside the product can enter the product through the lead terminals 5a, 5b, and 5c (poor sealing). .

The object of the present invention is to prevent the synthetic resin material from flowing into the resistor when molding the outer case, and thereby prevent the occurrence of paris.
Another object of the present invention is to provide a sealed variable resistor that can prevent moisture from entering the product even when a resin with high melt viscosity is used.

[Means to solve the problem]

The sealed variable resistor of the present invention includes a resistor formed on an insulating substrate, a brush that slides on the conductor, a rotary plate that fixes the brush, and the insulating substrate and lead terminals formed by insert molding. A sealed variable resistor having an outer case integrated using a method is characterized in that a substantially annular elastic body is adhered to the surface of the insulating substrate on which the resistor and conductor are formed.

〔Example〕

Next, the present invention will be explained with reference to the drawings. FIG. 1 is a perspective view of the main parts of a sealed variable resistor according to an embodiment of the present invention, and FIG. 2 is a sectional view after insert molding.

In Figures 1 and 2, 1 is an insulating substrate made of alumina ceramics, etc., 2 is a ruthenium oxide resistor formed in an arc shape on the top surface of the insulating substrate, and each end of the resistor 2 is Connected first conductors 3a, 3b made of silver or palladium and a second conductor 3C are printed and fired, and a silicone elastic body 4a is printed in an annular shape on the outer periphery of the resistor 2 and dried. Form. first and second conductor 3
Copper-based lead terminals 5a are provided at a, 3b, and 3c.

5b and 5c are connected by soldering or other means. The resistor element to which lead terminals 5a, 5b, and 5c are connected is housed in a mold for insert molding. The insert molding die presses the resistor 2 and a portion of the conductors 3a, 3b, 3c to expose the resistor 2 and a portion of the conductors 3a, 3b, 3c.

At this time, since the silicone elastic body 4a provided on the outer periphery of the resistor 2 is also pressed and compressed by the mold, it is possible to prevent the synthetic resin material from forming on the resistor 2 side during insert molding.

The parts shown in FIGS. 3(a) to 3(e) are sequentially assembled into the outer case 6 to complete the sealed variable resistor. In FIG. 3(a), 7 is a rotary plate with a driver arm on its upper surface, and a resistor 2 and conductors 3a, 3b, 3c on its lower surface.
A brush 8 that slides on the top is connected. 3(b) is an O-ring for sealing, and 10 in FIG. 3(a) is an upper lid. FIG. 3(d) shows an insert-molded outer case 6, where 1 is an insulating substrate and 5c is a lead terminal. Third
Figure (e) shows the sealed variable resistor of this example after assembly.

FIG. 4 is a longitudinal cross-sectional view of another embodiment of the present invention after insert molding. In contrast to the conventional sealed variable resistor element described above, in this embodiment, the diameter of the silicone elastic body 4b is larger and spreads outward compared to the first embodiment.
It is located inside the outer case 6. PPS with high melt viscosity
When a synthetic resin material such as resin is used, there is no need to press a part of the silicone elastic body 4b with a mold because no paris is generated. Therefore, there is an advantage that the resistor 2 can be made larger.

〔Effect of the invention〕

As explained above, the present invention is achieved by printing a silicone elastic body in an annular shape on the outer periphery of a resistor on an insulating substrate.
Since the silicone elastic body is sandwiched between the molds that press the insulating substrate and the resistor, no synthetic resin material flows into the resistor when molding the outer case. In other words, it has the advantage of preventing the occurrence of Paris.

Furthermore, since the silicone elastic body has better adhesion to the insulating substrate than PPS resin, it also has the advantage of preventing moisture from entering from the outside of the product.

[Brief explanation of the drawing]

Fig. 1 is a perspective view of an element for a sealed variable resistor according to an embodiment of the present invention, Fig. 2 is a vertical cross-sectional view of an insert-molded outer case, and Figs. 3 (a) to (e) are a sealed variable resistor element. FIG. 4 is a longitudinal sectional view of an insert-molded outer case according to another embodiment of the present invention, and FIG. 5 is a perspective view of a conventional sealed variable resistor element. 1... Insulating substrate, 2... Resistor, 3a, 3b, 3c
...Conductor, 4a, 4b...Silicone elastic body, 5a
. 5b, 5c...Lead terminal, 6...Exterior case, 7
...Rotating plate, 8...Brush, 9...0 ring, 1
0...Top lid.

Claims (1)

[Claims] A resistor formed on an insulating substrate, a brush that slides on the conductor, a rotating plate that fixes the brush, and an exterior case in which the insulating substrate and lead terminals are integrated using an insert molding method. In a sealed variable resistor having
A sealed variable resistor characterized in that a substantially annular elastic body is adhered and formed on the surface of the insulating substrate on which the resistor and the conductor are formed.