JPH0715842B2 - Manufacturing method of chip type semi-fixed resistor - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of manufacturing a chip-type semi-fixed resistor constructed so that a resistance value can be initialized after mounting.

[0002]

2. Description of the Related Art One of the methods of classifying resistors is a method of classifying whether or not the resistance value is variable. A resistor whose resistance value is fixed to a predetermined value in advance is called a fixed resistor, and a resistor whose resistance value can be changed appropriately is called a variable resistor. And, as what is functionally positioned between these,
There is a resistor that can obtain a desired resistance value after the circuit is mounted and is then fixed and used at that resistance value, which is called a semi-fixed resistor.

On the other hand, a chip-type resistor is one of the resistors classified according to the form. This was developed in response to the recent demands for downsizing of electronic equipment and the demand for automatic assembly, and it is usually a small rectangular chip so that it can be surface-mounted on a circuit board by an automatic machine with high density. Has the form of.

[0004]

Thus, even in the above-mentioned semi-fixed resistor, the need for chip formation increases,
A chip type semi-fixed resistor as shown in FIGS. 4 to 7 has been developed.

The present invention relates to a method of manufacturing such a chip type semi-fixed resistor. Therefore, first, the basic configuration of the chip type semi-fixed resistor will be described with reference to FIGS. 6 and 7.

A ceramic substrate 1 having a substantially rectangular shape in plan view has a through hole 2 formed in the center thereof, and a substantially horseshoe-shaped resistor film 3 having an arc portion centered on the through hole 2 is a thick film. It is formed by printing by a printing method. Both ends 3a, 3a of the resistor coating 3 are electrically connected to the electrode coatings 4, 4 extending from one side surface of the substrate 1 to the back surface. The electrode coatings 4 and 4 are also formed by printing or the like, like the resistor coating 3. The electrode coatings 4 and 4 are further solder-plated or nickel-plated and then solder-plated to form the external electrodes 4a and 4a.

On the other hand, a caulking shaft cylinder 6 integrally formed with a thin plate-shaped electrode fitting 5 is inserted into the through hole 2 from the back side of the substrate, and the caulking shaft cylinder 6 is slid on the substrate surface side end portion. The mover 7 is swaged so as to be rotatable around the swaged shaft cylinder 6. The electrode fitting 5 extends from the center of the back surface of the substrate to the other side of the substrate 1 along the back surface of the substrate, and has a tip bent in an L shape to form the external electrode 8 on the other side surface of the substrate 1.

The slider 7 has a substantially disk shape when seen in a plan view, and the resistor film 3 on the substrate is provided at an appropriate portion on the back surface thereof.
A contact portion 7a is formed in pressure contact with the surface of the. Also,
As can be seen from FIGS. 4 and 5, a plus groove 9 into which the driver bit is fitted is press-molded on the upper surface of the slider 7.

When the driver bit is fitted in the plus groove 9 and the slider 7 is rotated, the contact portion 7a thereof slides while contacting the arc portion of the horseshoe-shaped resistor film 3 and thereby. , Two external electrodes 4a, 4a on one side of the substrate
The resistance value between one of them and the external electrode 8 on the other side of the substrate changes. This is because the length of the resistor film 3 that conducts between them changes.

The slider 7 has a certain friction during its rotation by setting the degree of crimping engagement with the shaft cylinder 6 or the pressure contact force of the contact portion 7a against the resistor film 3 to a predetermined value. A resistance is given, and once it has been rotated as described above to obtain a predetermined resistance value, it does not rotate carelessly, and as a result, this chip type semi-fixed resistor is The resistance value will be used semi-fixedly.

By the way, when solder plating is applied to the electrode coatings 4 and 4, the resistor coating 3 is made of Teflon or silicon as shown in FIG. 5 so that unnecessary solder does not adhere to the resistor coating 3. A resin coating 10 is applied. The coating 10 has not been particularly removed in the past even after solder plating on the electrode coatings 4 and 4, and remains on the resistor coating 3 as it is after it is made into a product.

Therefore, the contact portion 7a of the slider 7 must break through the coating 10 and make electrical contact with the resistor film 3. To this end, it is necessary to increase the contact pressure of the contact portion 7a with respect to the resistor film 3 to a predetermined value or more, which causes a problem that the rotational resistance of the slider 7 becomes larger than necessary.

Thus, even if the slider 7 is rotated after the chip type semi-fixed resistor is mounted on the circuit board, the extent to which the coating of the contact portion 7a is broken is not stable, and the contact portion is eventually lost. There is also a problem that the contact state of 7a with the resistor film 3 becomes unstable.

Further, in order to set the reference resistance value of the entire length of the resistor film 3 to a predetermined value, conventionally, as shown in FIG. 6, slits 11 cut in the arc direction of the resistor film 3 in the width direction.
However, there is a problem in that the operation resistance linearly proportional to the rotation angle of the slider 7 cannot be obtained.

The present invention has been devised under the circumstances as described above, and it is possible to stabilize the contact state of the slider with the resistor film and to adjust the resistance value reliably and accurately. Moreover, it is an object of the present invention to provide a method for manufacturing a chip-type semi-fixed resistor that can obtain an operating resistance that is linearly proportional to the rotation angle of the slider.

[0016]

In order to solve the above problems, the method of the present invention takes the following technical means.

That is, a horseshoe-shaped resistor film having an arc portion centered on the through hole in plan view is formed on the upper surface of the substrate having the through hole in the center, and the resistor is provided on one side surface or the back surface of the substrate. After forming an electrode coating that is electrically connected to both ends of the coating, and applying a resin coating to the resistor coating, solder plating the electrode coating, on the other side of the substrate along the back surface of the substrate. The caulking shaft cylinder provided in the thin plate-shaped electrode fittings is inserted into the through hole, and the slider having the contact portion that comes into contact with the electrode coating is rotatably caulked to the tip of the caulking shaft cylinder. In the method of manufacturing a chip-type semi-fixed resistor consisting of the above, the resistor film is formed by printing a film having a thickness exceeding a target film thickness, and then the resin coating is applied to the surface of the film, After Ndamekki is characterized by the formation by exposure of the surface to remove a predetermined depth with the resin coating.

[0018]

In the method of the present invention, the resin coating on the surface of the resistor coating, which is essential when the electrode coating on both ends of the resistor coating is solder-plated, is deleted after the solder plating is performed, and at the same time, in advance. The surface of the resistor film is exposed by removing the resistor film having a thickness equal to or larger than the target film thickness.

This means that the slider does not break the resin coating and come into contact with the resistor film as in the conventional case.
It means that the slider can directly make electrical contact with the exposed surface of the resistor coating.

Therefore, according to the chip-type semi-fixed resistor manufactured by the method of the present invention, the slider is in stable contact with the resistor film, and the resistance value after mounting by rotating the slider is mounted. Adjustment can be performed more reliably.

In the method of the present invention, when the resistor coating is removed together with the resin coating as described above, the film thickness of the resistor coating at the time of printing is set to a target film thickness or more, and the above deletion is performed. At this time, the target film thickness is set. This means that the resistance value can be adjusted by controlling the film thickness of the resistor film, instead of adjusting the resistance value over the entire length of the resistor film by forming a slit in the width direction of the resistor film as in the past. To do. in this way,
As a result of being able to obtain the initial resistance value depending on the film thickness of the resistor film, it becomes possible to obtain an operating resistance value which is linearly proportional to the rotation of the slider.

[0022]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The embodiments of the present invention will be specifically described below with reference to FIGS. In these figures, the part relating to the basic structure of the chip type semi-fixed resistor is as already described with reference to FIGS. 4 to 7. However, the chip type semi-fixed resistor manufactured by the method of the present invention is manufactured. As shown in FIGS. 1 and 2, the surface of the resistor coating 3 is planarly exposed, and the contact portion 7a of the slider 7 is in direct contact with the exposed surface. 4 is different from the conventional example shown in FIG.

In the present invention, the resistor coating 3 is
It is formed by the following steps.

First, when the resistor coating 3 is formed by printing on the surface of the ceramic substrate 1, its thickness is made thicker than the target thickness t. In the embodiment, as shown in FIG. 3, after printing a relatively wide first-layer resistor film 31, a second layer having a width narrower than that of the first-layer resistor film 3a is printed. This is dealt with by printing the resistor coating 32 of FIG.

It is to be noted that the electrode coatings 4 and 4 which are electrically connected to both ends of the resistor coating 3 are formed on one side or the back surface of the substrate 1 as in the case of FIG. Specifically, the electrode coatings 4 and 4 are formed by printing by dividing the substrate surface portion and the substrate side surface or the back surface portion, and at least the substrate surface portion is formed by printing before printing the resistor coating 3. Has been done.

Subsequently, a resin coating 10 is applied on the resistor film 3 except the electrode films 4 and 4. For this, for example, silicone resin, Teflon resin or the like is adopted.

Next, the electrode coatings 4 and 4 are plated with solder to form external electrodes 4a and 4a. Since the resin coating 10 is applied to the resistor coating 3, solder does not adhere to it.

Then, as shown in FIG. 2, the resin coating 10 and the upper layer portion of the resistor film 3 are simultaneously removed,
The surface of the resistor film 3 is exposed. Specifically, the resin coating 10 and the resistor film 3 can be removed by sandblasting, grinding with a grindstone, or laser grinding.

At this time, the above-mentioned deletion may be carried out while controlling the film thickness of the resistor film 3 to a target film thickness, but the resistance value is monitored while monitoring the resistance value between the external electrodes 4a, 4a. If the above is deleted so that becomes the predetermined target value,
A more accurate initial value of the resistor film 3 can be obtained.

When the construction of the substrate 1 and its surface is completed as described above, the electrode fitting 5 and the slider 7 are then assembled in the same manner as described in the first half of this specification. Product is completed.

As shown in FIG. 2, in the chip type semi-fixed resistor having the resistor coating formed by the above method, the contact portion 7a of the slider 7 is directly connected to the resistor. Since the slider is in contact with the exposed surface of the film 3, stable contact of the slider with the film 3 of the resistor can be obtained, and the film thickness of the film 3 of the resistor must be controlled to be exactly the target film thickness. You will be able to

[Brief description of drawings]

FIG. 1 is a cross-sectional view of a chip type semi-fixed resistor manufactured by a method of the present invention, which is a view corresponding to a cross section taken along line VV of FIG. 4.

FIG. 2 is an enlarged view of part A in FIG.

FIG. 3 is an explanatory diagram of a method of forming a resistor film 3.

FIG. 4 is a plan view of a chip type semi-fixed resistor which is a premise of the present invention.

5 is a sectional view taken along line VV of FIG.

6 is a sectional view taken along line VI-VI of FIG.

7 is a rear view of the chip type semi-fixed resistor shown in FIG. 4. FIG.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Ceramic substrate 2 Through hole 3 Resistor film 4 Electrode film 5 Electrode metal fitting 6 Caulking shaft cylinder 7 Slider 7a Tactile part 10 Resin coating

Claims (1)

[Claims] 1. A horseshoe-shaped resistor coating having an arc portion centered on the through hole in plan view is formed on the upper surface of the substrate having the through hole in the center, and the resistor is provided on one side surface or the back surface of the substrate. While forming an electrode coating that is electrically connected to both ends of the coating, and applying a resin coating to the resistor coating, while solder plating the electrode coating,
Insert the caulking shaft cylinder provided in the thin plate-shaped electrode fitting along the back surface of the substrate to the other side of the substrate through the through hole, and
In a method of manufacturing a chip-type semi-fixed resistor, which comprises rotatably crimping a slider having a contact portion that comes into contact with the electrode coating to a tip portion of the caulking shaft cylinder, the resistor coating is a target film. Form by forming a coating film with a thickness exceeding the thickness, applying the resin coating on the surface, solder plating on the electrode coating, and removing the predetermined depth together with the resin coating to expose the surface. And a method for manufacturing a chip-type semi-fixed resistor.