JPH0523504U - Surge absorber with built-in resistor - Google Patents

Abstract

(57) [Abstract] [Purpose] To provide a surge absorber having a built-in varistor element and a resistance element, in which the resistance element can be easily formed and a precise resistance value can be stably obtained. For the purpose. At least one varistor green sheet provided with internal electrodes 1 and 3 reaching a side edge portion or an end portion has at least one varistor green sheet.
A green sheet having a plurality of through holes is superposed with a green sheet provided with a pair of extraction electrodes 8 reaching from the both ends of the sheet to the portions corresponding to the through holes on the upper surface, and the sheets are pressure-bonded and fired to form a laminate. 10 is formed, and this laminated body 10 is formed.
External electrodes connected to corresponding internal electrodes or lead electrodes are provided at both ends and an intermediate portion on the outer surface of the above, and the resistor paste is poured into the concave portion 11 of the laminate 10 formed by the through holes to form a resistor. Surge absorber with built-in resistor.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 This invention consists of a resistor built-in surge absorber that absorbs and removes voltage surges and current surges that enter the line, and more specifically, a varistor element that suppresses voltage surges and a resistor element that suppresses current surges are composed of a single chip component. It is related to the formation of resistors in the surge absorber.

[0002]

[Prior Art]

 For example, a circuit combining a varistor element that suppresses a voltage surge and a resistor element that suppresses a current surge is employed as surge protection for a portion where the element is easily destroyed by an external surge, such as an IC input terminal.

By the way, if a circuit is configured by using separate parts for a varistor element and a resistance element, it takes time and labor to mount them on a printed circuit board, the work cost is high, and a large area is required in terms of space. Therefore, a surge absorber with a built-in resistor has been devised, which consists of a varistor element and a resistance element in one chip component.

The chip-shaped surge absorber with a built-in resistor shown in FIG. 5 is obtained by stacking a plurality of varistor green sheets provided with internal electrodes and press-bonding and firing to form a chip-shaped laminated body 21. The external electrodes 14, 15, 16 are formed on the outer surfaces of both ends and the intermediate portion, and the resistor 22 is formed by printing a resistance paste between the external electrodes 14, 15 on the upper end surface of the laminate 21.

The external electrodes 14 and 15 at both ends are electrically connected to the resistor 22, the one external electrode 14 is electrically connected to one side of the internal electrode which constitutes the varistor element, and the intermediate external electrode 16 is an internal electrode. The other end of the internal electrode is electrically connected to form a varistor element in the laminated portion of the plurality of internal electrodes, and a resistor element 22 is applied and baked on the laminated body 21 to form a resistive element. As shown in the equivalent circuit of FIG. 7, the laminated body 21 has a surge absorber with a built-in resistor including a varistor element Z and a resistance element R.

Next, the surge absorber with a built-in resistor shown in FIG. 6 is one in which a resistance element is incorporated as an internal electrode of a chip-shaped laminated body and integrally fired, and a resistor 23 is applied to the surface so as to reach both ends. The formed ceramic green sheet (may be a varistor green sheet) is added to the varistor green sheet formed by applying the internal electrodes 1 and 3, and the sheets are vertically stacked to form a laminated body 21a. When 16 is formed, a surge absorber with a built-in resistor having the equivalent circuit shown in FIG. 7 in which the varistor element Z and the resistance element R are built in the chip-shaped laminated body 21a can be obtained.

[0007]

[Problems to be solved by the device]

 By the way, in both of the surge absorbers with built-in resistors shown in FIGS. 5 and 6, the resistance elements 22 and 23 are formed by screen printing or the like to obtain the resistance elements. Therefore, the resistance value of the resistance element is , 23 depending on the thickness and shape.

Therefore, in order to stably supply the resistance value of the product, it is necessary to control the thickness of the film during the formation of the resistor, the protrusion, the bleeding at the resistor interface during firing, and the like. Very difficult to manage.

Further, the laminated body of the chip varistor for forming the resistor is very small, and the work of directly printing on this element is very difficult.

The present invention has been made to solve the above problems, and provides a surge absorber with a built-in resistor in which a resistor can be easily formed and a precise resistance value can be stably obtained. The purpose is to

[0011]

Means for Solving the Problems In order to solve the above problems, the present invention has at least one through hole on a plurality of varistor green sheets provided with internal electrodes reaching side edges or edges. A green sheet is sandwiched between green sheets having a pair of extraction electrodes reaching from the both ends of the sheet to the portions corresponding to the through holes on the upper surface, and the sheets are pressure-bonded and fired to form a laminated body. External electrodes connected to the corresponding internal electrodes or lead-out electrodes are provided at both ends and the middle part on the outer surface of the resistor, and the resistor paste is poured into the concave portion of the laminate formed by the through holes to form a resistor built-in surge. It is an absorber.

[0012]

[Action]

 The resistor is formed by pouring the paste into the recess formed in the upper part of the laminated body.Therefore, if the amount of paste is controlled to be constant, the thickness of the resistor will be constant and a precise resistance value will be stable. Can be supplied.

[0013]

【Example】

 Hereinafter, an embodiment of the present invention will be described with reference to FIGS. 1 to 4 of the accompanying drawings.

In the embodiment shown in FIGS. 1 to 4, in order to form a varistor element, a varistor green sheet 2 provided with internal electrodes 1 reaching both side edges and an internal electrode 3 reaching one end are provided. A varistor green sheet 4 and varistor green sheets 5 and 5 for upper and lower ends without forming internal electrodes are prepared, and the number and combination of these sheets are selected.

Further, in order to form a resistance element, a green sheet 7 having a through hole 6 and a green sheet 9 having an extraction electrode 8 reaching both ends are provided. Both extraction electrodes 8, 8 of the green sheet 9 are formed so as to reach the through holes 6 when they are overlapped with the green sheet 7.

For each varistor green sheet, for example, a ZnO-based varistor material is used, and a material such as Ag-Pd is used for the internal electrodes 1 and 3 and the extraction electrode 8.

In the illustrated case, two varistor green sheets 2, three varistor green sheets 4 and two varistor green sheets 5 for the upper and lower ends are used, and further two green sheets 7 and one sheet. Using the green sheet 9 of FIG. 1, the sheets are stacked one above the other with the through holes 6 facing upward in the combined state as shown in FIG. 1, and the sheets are pressure-bonded and fired to form a chip-shaped laminated body 10 as shown in FIGS. 2 and 3. To form.

As shown in FIG. 2, in the laminated body 10 after firing, the resistance paste 12 poured from the dispenser is poured into the concave portion 11 formed by the through hole 6.

As shown in the sectional view of FIG. 3, the resistance paste 12 spreads in the recess 11 to form the resistor 13. Since the area of the resistor 13 is constant due to the concave portion 11, the thickness t of the resistor 13 is determined in proportion to the amount of the paste 12 to be injected.

By the way, since the resistance value is determined by the thickness t of the resistor 13, the amount of the paste 12 is set to an amount that gives the thickness t corresponding to the required resistance value, and the paste of the paste poured from the dispenser is used. If the quantity is controlled to be constant, the resistance value obtained will also be constant.

Next, external electrodes 14, 15 and 16 are formed on the outer surfaces of both end portions and the intermediate portion of the laminated body 10 by plating or thick film coating as shown in FIG. The resistance paste 12 may be injected after the external electrodes 14, 15, 16 are formed.

The external electrodes 14 and 15 at both ends are electrically connected to the resistor 13 through the extraction electrode 8, one external electrode 14 is further electrically connected to one internal electrode 3, and the intermediate external electrode 16 is the other. The internal electrodes 1 are electrically connected to each other, whereby a varistor element is formed in the laminated portion of the internal electrodes 1 and 3, and a resistive element is formed by the resistor 13 formed on the laminated body 10. A surge absorber with a built-in resistor including a varistor element and a resistance element in one chip-shaped laminated body 10 can be obtained.

Thus, the surge absorber with a built-in resistor according to the present invention forms an equivalent circuit shown in FIG. The external electrode 14 is connected to the surge input side, the external electrode 15 is connected to an IC or the like to be protected from the surge, 16 is a ground terminal, and the varistor element Z suppresses the voltage surge intruding from the power supply side, and the current surge. Is suppressed by the resistance element R.

The surge absorber with a built-in resistor according to the present invention is not limited to the one in the above embodiment, and may be appropriately modified in terms of the number of laminated internal electrodes, the sheet thickness, the shape of through holes, the number of sheets having through holes, and the like. It should be carried out.

[0025]

[Effect of the device]

 As described above, according to the present invention, the varistor element and the resistance element can be formed in one chip-shaped laminated body, and the resistance element is formed by pouring the resistance paste into the concave portion on the laminated body. As long as the amount of paste to be poured is controlled to a constant value, the resistor has a constant thickness and a precise resistance value can be obtained, and the product characteristics can be supplied in a stable manner. Since a resistor can be formed on the substrate, the manufacturing cost can be reduced.

[Brief description of drawings]

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

FIG. 2 is a perspective view of a laminated body obtained by crimping and firing the surge absorber according to the present invention.

FIG. 3 is a cross-sectional view of a laminated body obtained by crimping and firing the surge absorber according to the present invention.

FIG. 4 is a perspective view of a laminated body provided with external electrodes.

FIG. 5 is a perspective view of a conventional surge absorber.

FIG. 6 is a perspective view of another example of a conventional surge absorber.

FIG. 7 is a circuit diagram of a surge absorber with a built-in resistor.

[Explanation of symbols]

 1,3 Internal electrode 2,4,5 Varistor green sheet 6 Through hole 7,9 Green sheet 8 Extraction electrode 10 Laminated body 11 Recessed portion 12 Resistive paste 13 Resistor 14, 15, 16 External electrode

Claims (1)

[Scope of utility model registration request] 1. A green sheet having at least one through hole on a plurality of varistor green sheets provided with internal electrodes reaching side edges or edges, and a green sheet having at least one through hole on a top surface corresponding to the through holes from both ends of the sheet. To sandwich the green sheets provided with a pair of extraction electrodes, and press-fire these sheets to form a laminated body. At the outer surface of this laminated body, at both end portions and intermediate portions, corresponding internal electrodes or lead-out electrodes are formed. A surge absorber with a built-in resistor in which an external electrode connected to an electrode is provided and a resistor is formed by pouring a resistor paste into a concave portion of the laminated body formed by the through hole.