JP2573665Y2 - Surge absorber with built-in resistor - Google Patents

Description

[Detailed description of the invention]

[0001]

This invention relates to a surge absorber with a built-in resistor for absorbing and removing a voltage surge and a current surge that enter a line, and more specifically, a varistor element for suppressing a voltage surge and a resistor element for suppressing a current surge. The present invention relates to a surge absorber composed of chip components.

[0002]

2. Description of the Related Art For example, as an input terminal of an IC or the like, surge protection at a place where an element is easily damaged by an external surge includes:
As shown in FIG. 13, a circuit is used in which a varistor element Z for suppressing a voltage surge and a resistance element R for suppressing a current surge are combined.

[0003]

In the above-described conventional circuit for taking measures against external surges, since separate components are used for the varistor element Z and the resistance element R, it takes time and effort to mount it on a printed circuit board. However, there is a problem that the operation cost is high and a large area is required in terms of space.

Accordingly, the present invention provides a surge absorber with a built-in resistor, in which a varistor element and a resistive element can be constituted by one chip component, which can be easily mounted, the operation is inexpensive and the space is advantageous. It is intended to be.

[0005]

In order to solve the above-mentioned problems, the present invention provides a varistor green sheet provided with internal electrodes reaching both side edges, and a varistor green sheet provided with internal electrodes reaching one end. The number and combination of the sheets are selected and laminated, and this is press-bonded and fired to form a laminate . On the outer surface of the laminate , one end is provided at one end.
External electrode connected to the internal electrode reaching
External electrodes that are not connected to the internal electrodes
An external electrode connected to the internal electrodes to reach the edges provided respectively, is obtained by employing the structure in which the resistive electrode across the external electrodes of the laminate.

[0006]

[Function] A varistor green sheet provided with internal electrodes reaching both side edges and a varistor green provided with internal electrodes reaching one end are selected and laminated in a selected number, and then laminated by pressing and firing. Oite the outer surface of the body, one end portion
In the middle part of the laminate, an external electrode conducting to the internal poles reaching both side edges is provided, and in the middle part of the laminate, the external electrode at both ends is provided. Providing conductive resistive electrodes provides resistance between external electrodes at both ends of the laminate within one chip laminate.
Varistor between one external electrode at the end and the external electrode at the middle
It is possible to obtain a surge absorber with a built-in resistor having
The mounting work at the time of mounting on the printed circuit board can be easily performed, and the space can be saved.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIGS.

In the first embodiment shown in FIGS. 1 to 5, a varistor green sheet 2 provided with internal electrodes 1 extending to both side edges is provided to form a chip-shaped surge absorber with a built-in resistor. A varistor sheet 4 provided with internal electrodes 3 to be reached and varistor green sheets 5 and 5 for upper and lower ends where no internal electrodes are formed are prepared, and the number and combination of these sheets are selected.

In the case shown in the figure, two varistor green sheets 2, one varistor green sheet 4 and two varistor green sheets 5 for upper and lower ends are used, and each sheet is turned up and down in a combined state as shown in FIG. The layers are laminated and fired under pressure to form a chip-shaped laminated body 6 as shown in FIGS.

The varistor green sheets are made of, for example, a ZnO-based varistor material, and the internal electrodes 1 and 3 are made of a material such as Ag-Pd.

As shown in FIG. 4, a resistance electrode 7 is applied to one surface of the fired laminate 6 so as to reach both ends and fired. The resistance electrode 7 is made of a material such as a carbon resistor and a cermet resistor.

Next, the external electrodes 8, 9, 10 are plated or thick-film coated on the outer surfaces of both ends and an intermediate portion of the laminated body 6.
Is formed as shown in FIG. The resistance electrode 7 may be formed after the formation of the external electrodes 8, 9, 10.

The external electrodes 8 and 9 at both ends are electrically connected to the resistance electrode 7, one external electrode 8 is further electrically connected to the internal electrode 3, and the intermediate external electrode 10 is electrically connected to the internal electrode 1. As a result, the varistor element Z is formed at the laminated portion of the internal electrodes 1 and 3, and the resistive element R is formed by the resistive electrode 7 applied and baked on the laminated body 6. As shown in the equivalent circuit of FIG. A resistor built-in surge absorber 11 having a varistor element Z and a resistance element R in one chip-shaped laminated body 6
Is obtained.

Next, in the second embodiment shown in FIG. 7, parts are given directionality by the shape of the resistance electrode, and the same parts as those in the first embodiment will be described using the same reference numerals. I do.

A resistance electrode 7a made of a material such as carbon resistance or cermet resistance is applied to the laminated body 6 fired by the same means as in the first embodiment so as to reach both ends of the laminated body 6 and fired. The resistance electrode 7a is formed in a tapered shape so that the width is narrow at one end and wide at the other end.

Of course, the formation of the resistance electrode 7a may be performed before or after the formation of the external electrodes 8, 9, 10. Thus, the surge absorber 11a having the equivalent circuit shown in FIG. 6 is obtained.

The surge absorber 11a has a tapered shape in which the width of the portion of the resistance electrode 7a connected to the external electrode 8 is wider than the width of the resistance electrode on the other external electrode 9 side. And the external electrode 8 connected to both the varistor element Z and the resistance element R and the external electrode 9 connected only to the resistance element R can be distinguished at a glance. It is possible to eliminate mistakes such as erroneous mounting directions of components when mounting the components.

The shape of the resistance electrode 7a in the second embodiment is not limited to the tapered one described above.
The shape on the one external electrode 8 side and the shape on the other external electrode 9 side of the resistance electrode need only be asymmetric, and in other words, it is only necessary to provide directionality to the surge absorber component.

Next, in a third embodiment shown in FIGS. 8 to 11, the resistance element is formed by assembling it inside the chip-shaped laminated body and integrally firing it. The same parts as those in the first embodiment will be described using the same reference numerals.

As shown in FIG. 8, a varistor green sheet 12 and an intermediate varistor green sheet 13 having a resistance electrode 7 made of nichrome or the like applied on both surfaces to reach both ends are added to the first embodiment. Are stacked in a state of being combined with the arrangement shown in FIG. 7 and laminated by pressing and firing, so that the chip-shaped laminate 6 shown in FIGS.
b is formed.

As shown in FIG. 11, external electrodes 8, 9 and 10 are formed on the outer surfaces of both ends and an intermediate portion of the laminated body 6b. Then, one external electrode 8 is electrically connected to the internal electrode 3, and further, the intermediate external electrode 10 is electrically connected to the internal electrode 1.

As a result, a surge absorber 11b having an equivalent circuit shown in FIG. 6 in which the varistor element Z and the resistance element R are built in the chip-shaped laminated body 6b is obtained.

FIG. 12 shows the above-described surge absorber 11b.
Is mounted on a printed circuit board. The external terminal 8 on one end is connected to the signal pattern 14, the external terminal 9 on the other end is connected to the pin 16 of the IC 15, and the intermediate external electrode 10 is grounded. Connected to the pattern 17, the voltage surge on the IC 15 is suppressed by the varistor element Z, and the current surge is suppressed by the resistance element R.

As described above, the surge absorber 11b
Has a three-terminal structure, and as shown in FIG.
The mounting can be performed continuously at the root of the pin 16, which is advantageous in terms of space.

Since the surge absorbers 11, 11a and 11b in the first to third embodiments use a laminated structure, the characteristics of the varistor element Z and the resistance element R are determined by the pattern area of the internal electrodes, the number of layers, and the sheet thickness. By controlling the pattern area of the resistive electrode, the adjustment can be made independently.

[0026]

As described above, according to the present invention, a varistor element and a resistance element can be formed in one chip-shaped laminate, and space saving and mounting cost can be reduced when mounted on a printed circuit board. it can.

Since the three-terminal laminated structure is used, the characteristics of the varistor element and the resistive element can be individually controlled by the pattern area of the internal electrode and the resistive electrode, the number of laminated internal electrodes, and the sheet thickness.

[Brief description of the drawings]

FIG. 1 is an exploded perspective view of a portion forming a varistor element of a surge absorber according to the present invention.

FIG. 2 is a perspective view of a laminate obtained by pressure-bonding and firing the varistor element of the surge absorber according to the present invention.

FIG. 3 is a longitudinal sectional view of a laminate obtained by pressure-bonding and firing a varistor element of a surge absorber according to the present invention.

FIG. 4 is a perspective view in which a resistive electrode is provided on a laminate.

FIG. 5 is a perspective view of a surge absorber in which external electrodes are provided on a laminate.

FIG. 6 is an equivalent circuit diagram of a surge absorber in which external electrodes are provided on a laminate.

FIG. 7 is a perspective view showing a second embodiment of the surge absorber according to the present invention.

FIG. 8 is an exploded perspective view showing a third embodiment of the surge absorber according to the present invention.

FIG. 9 is a perspective view of a third embodiment of the surge absorber according to the present invention, showing a press-fired state of the surge absorber.

FIG. 10 is a longitudinal sectional view of a third embodiment of the surge absorber according to the present invention.

FIG. 11 is a perspective view of a surge absorber according to a third embodiment of the present invention, in which external electrodes are provided.

FIG. 12 is a plan view showing a mounted state of a surge absorber.

FIG. 13 is a circuit diagram for performing conventional surge protection.

[Explanation of symbols]

 1,3 Internal electrode 2,4,5 Varistor green sheet 6,6b Laminated body 7,7a Resistive electrode 8,9,10 External electrode 11,11a, 11b Surge absorber 12,13 Varistor green sheet

Claims (2)

(57) [Scope of request for utility model registration] 1. A varistor green sheet provided with internal electrodes reaching both side edges and a varistor green sheet provided with internal electrodes reaching one end are selected and laminated in a selected number and in combination, and are baked under pressure. Forming a laminate , at one end of the outer surface of the laminate reaches said one end
An external electrode connected to the internal electrode and an internal electrode at the other end
The external electrode not connected, an intermediate portion provided people each external electrode connected to the internal electrode Ru reach to <br/> the opposite side edges, built-in resistors surge having a resistive electrode across the external electrodes of the laminate Absorber. 2. The surge absorber with a built-in resistor according to claim 1, wherein the shape of the resistance electrode on one external electrode side and the shape on the other external electrode side are asymmetric.