JP2000091102A - Trimmable chip resistor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a trimmable chip resistor capable of properly determining a trimming cut-out position. SOLUTION: A resistor layer 30 and upper surface electrode layers 22 are formed on an insulating substrate 10. On a region where the resistor layer 30 and the upper surface electrode layers 22 are overlapped, the upper surface electrode layers 22 are formed being stacked on the resistor layer 30. As a result, a part existing between the upper surface electrode layers 22 on the resistor layer 30 can be surely recognized by image recognition, so that a trimming cut-out position can be properly determined.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a trimmable chip resistor.

[0002]

2. Description of the Related Art Trimmable chip resistors are generally used as chip resistors in which a protective layer provided on the upper end is formed transparent or translucent and can be trimmed after being attached to a wiring board. Here, in the conventional trimmable chip resistor B, the resistor layer 30 is formed on the upper electrode layer 22 as shown in FIGS. That is, the electrode portions 20 are formed at both ends of the insulating substrate 10, the upper electrode layer 22 in the electrode portion 20 is formed on the insulating substrate 10, and the resistor layer 30 is formed on the upper electrode layer 22. I have. A transparent or translucent protective layer 40 is formed to cover the resistor layer 30 and a part of the upper electrode layer 22. When performing trimming, the position of the resistor layer is recognized by image recognition, and the trimming cutout position is calculated and determined from the edge of the resistor layer.

[0003]

However, in the above-described conventional trimmable chip resistor, since the resistor layer 30 is formed on the upper electrode layer 22, the trimming position may be shifted. Was. That is, the resistor layer 30
When the position of the upper electrode layer 22 is shifted from that of the upper electrode layer 22, the actual center position L of the resistor layer 30 and the center position M between the ends of the upper electrode layer 22 are shifted as shown in FIG. If the trimming cutout position is determined based on the edge of the resistor layer 30, the trimming groove may reach the upper electrode layer 22, as shown in FIG. In that case, the inherent characteristics of the resistor may not be satisfied. Therefore, an object of the present invention is to provide a trimmable chip resistor that can appropriately determine a trimming cutout position in a trimmable chip resistor.

[0004]

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems. First, the present invention relates to a trimmable chip resistor having a resistor formed on an insulating substrate. A body layer, a pair of upper electrode layers connected to the resistor layer, wherein at least a part of each upper electrode layer is formed so as to overlap the resistor layer; A protective layer covering at least a part of the electrode layer and the resistor layer. In the trimmable chip resistor of the present invention, since the upper electrode layer is formed on the resistor layer, the center of the resistor layer recognized by image recognition is always the center of the upper electrode layer, that is, the actual center of the resistor layer. Since it becomes the center of the portion functioning as a resistor, a fixed position can be set as a trimming cutout position.

[0005]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described with reference to the drawings. The trimmer chip resistor A according to the first embodiment of the present invention is shown in FIGS.
As shown in FIG. 4, the insulating substrate 10 and the electrode portion 20
And a resistor layer 30 and a protective layer 40. FIG. 1 is a sectional view taken along line XX of FIG.

The insulating substrate 10 has a substantially rectangular parallelepiped shape mainly made of alumina, and has a substantially rectangular shape when viewed in plan. The resistor layer 30 is formed on the insulating substrate 10 with a substantially uniform thickness. The resistor layer 30 has a substantially rectangular shape in plan view. The resistor layer 30 is provided by, for example, screen-printing and baking a resistor paste of, for example, ruthenium oxide or the like in the above-described position in a substantially uniform shape with a substantially uniform film thickness.

The electrode portions 20 are provided in a pair on the left and right. As shown in FIG. 1, the upper electrode layer 22, the side electrode layer 24, the nickel plating layer 26, and the solder plating layer 28 are combined. Have. Here, the upper electrode layer 22
Are provided on the insulating substrate 10 so as to face each other with a substantially uniform thickness, and have a substantially convex shape in plan view. The inner end of the upper electrode layer 22 is formed so as to overlap the resistor layer 30. That is, in a region where the upper electrode layer 22 and the resistor layer 30 overlap, the resistor layer 30 is formed on the lower side. The upper electrode layer 22 is usually formed of a silver-based material.

The side electrode layer 24 covers a part of the upper electrode layer 22, a side surface of the insulating substrate 10, and a part of a lower surface of the insulating substrate 10 with a substantially uniform film thickness. . The side electrode layer 24 is usually formed of a silver-based material. The nickel plating layer 26 is provided with a substantially uniform film thickness on the side electrode layer 24 and is electroplated. The nickel plating layer 26 is provided to prevent the upper electrode layer 22 from being eluted into the solder, and functions as a solder elution prevention layer. In some cases, copper is used instead of nickel.

Further, the solder plating layer 28 is provided on the nickel plating layer 26 with a substantially uniform thickness.
Electroplated. This solder plating layer 28
Is provided for improving soldering, and functions as a soldering support layer. That is, without the solder plating layer 28, the nickel plating layer 26 is easily oxidized. The solder plating layer 28 is usually formed of solder, but may be formed of tin instead of solder. Of the above-mentioned electrode portions 20, those on the upper surface are referred to as upper electrode portions 20a, those on the side surfaces are referred to as side electrode portions 20b, and those on the lower surface are referred to as lower electrode portions 20c.

As shown in FIGS. 1 and 2, the protective layer 40 includes a portion of the upper surface of the insulating substrate 10, a portion of the upper surface of the pair of upper electrode layers 22, and the resistor layer. 30 is formed so as to be superposed on a part of the upper surface thereof. The protective layer 40 is usually formed of lead borosilicate glass, epoxy, phenol, silicon, polyimide resin, or the like. In this embodiment, since the present embodiment is a trimmable chip resistor, the protective layer 40 is formed of a transparent or translucent material, and the resistor layer 30 is visible.

The use state of the trimmer chip resistor A having the above configuration will be described. First, a case where the trimming is performed on the trimmer chip resistor A will be described. In this case, as in the conventional case, the position of the resistor layer is recognized by image recognition, the trimming cutout position is calculated and determined from the edge of the resistor layer 30, and trimming is performed from the trimmed cutout position.

At this time, in the trimmer chip resistor A of the present embodiment, both ends of the resistor layer 30 are connected to the upper electrode layer 2.
2, the predetermined position in the resistor layer 30 can be set as a trimming cutout position. For example, as shown in FIG. 3, when the resistor layer 30 is formed with a shifted position, the range recognizable by image recognition is the portion shown by hatching in FIG. 3. Therefore, trimming is performed according to the recognized region. If the cutout position is calculated, there is no possibility that the trimming groove reaches the upper electrode layer 22. Further, as shown in FIG.
Even if the position 2 is shifted, the range recognizable by the image recognition is the portion shown by the hatching in FIG. 4. Therefore, if the trimming cutout position is calculated in accordance with the recognized region, the trimming groove will have the upper surface electrode. There is no risk of reaching the layer 22. The same applies to the case where both the resistor layer 30 and the upper electrode layer 22 are shifted. That is,
Since the portion existing between the upper electrode layers 22 in the resistor layer 30 can be reliably recognized by image recognition, and the center of the recognized resistor layer is always the center of the portion of the upper electrode layer that functions as the actual resistance. A fixed position can be set as a trimming cutout position. As described above, since the trimming cutout position can be appropriately detected, the trimming cutout resistor is particularly suitable for downsizing.

In the image recognition, the resistor layer 3
0 and other members, that is, the upper electrode layer 22 and the insulating substrate 1
It is desirable to set a color or the like so that 0 can be appropriately recognized as an image. For example, the resistor layer 30 is recognized as black, while the other members are recognized as white. When mounting the trimmable chip resistor A having the above configuration, the chip resistor A having the above configuration is mounted on the wiring board with the lower surface of the chip resistor A facing down, that is, the wiring board side, as in the related art. .

1 and 2, the resistor layer 30 is shown as having a length substantially half the distance between the ends of the insulating substrate 10, but the resistor layer 30 is It may be formed up to the end of the insulating substrate 10,
It may be formed to an intermediate position between the end of the insulating substrate 10 and the end of the protective layer 40.

[0015]

According to the trimmable chip resistor of the present invention, since the upper electrode layer is formed so as to overlap the resistor layer, the center of the resistor layer recognized by the image recognition must be at the center of the upper electrode. Since it becomes the center of the portion of the layer that functions as the actual resistance, a fixed position can be set as the trimming cutout position, and the trimming cutout position can be determined appropriately.

[Brief description of the drawings]

FIG. 1 is a sectional view showing a trimmable chip resistor according to an embodiment of the present invention.

FIG. 2 is a plan view showing a trimmable chip resistor according to an embodiment of the present invention.

FIG. 3 is an explanatory diagram for explaining the operation and effect of the trimmable chip resistor according to the embodiment of the present invention.

FIG. 4 is an explanatory diagram for explaining the operation and effect of the trimmable chip resistor according to the embodiment of the present invention.

FIG. 5 is a sectional view showing a conventional trimmable chip resistor.

FIG. 6 is a plan view showing a conventional trimmable chip resistor.

FIG. 7 is an explanatory diagram for explaining a problem of a conventional trimmable chip resistor.

FIG. 8 is an explanatory diagram for explaining a problem of a conventional trimmable chip resistor.

[Explanation of symbols]

 Reference Signs List A Trimmable chip resistor 10 Insulating substrate 20 Electrode part 22 Top electrode layer 24 Side electrode layer 26 Nickel plating layer 28 Solder plating layer 30 Resistor layer 40 Protective layer

Claims (1)

[Claims] 1. A trimmable chip resistor, comprising: a resistor layer formed on an insulating substrate; and a pair of upper electrode layers connected to the resistor layer.
An upper electrode layer in which at least a part of each upper electrode layer is formed on the resistor layer, and a protective layer that covers at least a part of the upper electrode layer and the resistor layer. Features trimmable chip resistors.