JPH0855710A - Multilater voltage-nonlinear resistor - Google Patents

Abstract

PURPOSE:To provide a multilayer voltage nonlinear resistor of which the actual surge voltage resistance corresponds to a design value and which can be used safely and has high reliability. CONSTITUTION:A multilayer body 3 is constituted by alternately piling up ceramic green sheets 1 and internal electrodes 2 one upon another. The number of internal electrodes 2 used in the multilayer body is set at an even number and the sheets 1 and electrodes 2 are stuck to each other by pressing them against each other so that the lead-out sections 5 of the electrodes 2 can alternately become opposite to each other and the multilayer body is united in one body by sintering. A multilayer voltage-nonlinear resistor is formed by electrically connecting external electrodes 4 in parallel with the electrodes 2. In the first electrode layer 6 of the internal electrode layers having leading-out sections 5 on one side and the second electrode layer 7 on the opposite side, the current densities in the electrodes 2 of the layers 6 and 7 become constant and the layers 6 and 7 have the same surge current resistance, since the layers 6 and 7 have the same numbers of electrodes and leading-out sections. Therefore, a laminated voltage nonlinear resistor the actual surge current rsistance of which corresponds to its design value and which has excellent safety and reliability can be obtained.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a voltage non-linear resistor, and more particularly to a laminated type voltage non-linear resistor in which internal electrodes are laminated.

[0002]

2. Description of the Related Art A voltage non-linear resistor called a varistor is an element in which the resistance significantly decreases as the voltage increases and the flowing current increases. This voltage non-linear resistor is widely used to protect a device or parts from a surge current generated inside or outside the device. In addition, with the recent demand for miniaturization of electronic devices, a laminated voltage non-linear resistor, which is smaller than a disk type and can be mounted on the surface of a substrate in a space-efficient manner, is now in widespread use.

An example of such a conventional laminated type voltage non-linear resistor will be described below. That is, as shown in FIG. 3, the laminated voltage nonlinear resistor includes a laminated body 3 in which a plurality of ceramic green sheets 1 and internal electrodes 2 are alternately laminated, and an external electrode 4 provided on the outer surface thereof. Is equipped with. The ceramic green sheet 1 is formed in a rectangular sheet shape using a varistor composition material that exhibits a varistor function after sintering. Here, the varistor function is a function in which the resistance value changes non-linearly depending on the voltage.

The internal electrode 2 is a rectangular conductive sheet, and one side thereof is a lead-out portion 5 exposed to the outside. Further, around the three sides of the internal electrode 2 other than the lead-out portion 5, a margin portion is provided so as not to be exposed to the outside, and the ceramic green sheet 1 is laminated. And
The plurality of internal electrodes 2 and the ceramic green sheets 1 are laminated and pressure-bonded so that the lead-out portions 5 of the internal electrodes 2 are alternately on opposite sides, and the laminated body 3 is formed by sintering and integration. Further, external electrodes 4 are respectively connected to the exposed end portions of the lead-out portion 5 in the laminated body 3 in two opposite directions. The internal electrodes 2 are electrically connected in parallel by the external electrodes 4.

[0005]

The laminated type voltage non-linear resistor having the above structure is small and has excellent current / voltage characteristics. However, while the electrodes in the conventional disc type voltage non-linear resistor are surface-connected, in the laminated type voltage non-linear resistor, the thickness of one layer of the internal electrode 2 is 2 to 5 μm, so that the external electrode The connection portion with 4 is very thin and is in a state close to a line connection. Therefore, in order to obtain a sufficient current capacity, it is necessary to stack a plurality of internal electrodes 2 to secure a connection length (effective connection area). That is, the surge current withstand capability is determined by the current capacity of the effective connection area that is the connection portion between the internal electrode and the external electrode.
Therefore, in the laminated voltage non-linear resistor, the surge current withstand capability is designed by the number of laminated internal electrodes.

However, if the surge current resistance is designed only by the number of laminated internal electrodes, the number of laminated layers may be an odd number. At this time, the number of lead-out portions is not the same at the two opposite end portions of the laminated body where the lead-out portions of the internal electrodes are exposed. Here, when the internal electrode layer having the lead-out portion 5 exposed on one side of the laminated body 3 is the first electrode layer 6 and the internal electrode layer having the lead-out portion 5 exposed on the opposite side is the second electrode layer 7, The electrode layer 6 and the second electrode layer 7 have the same current capacity. Therefore, on the side of the internal electrode layer (first electrode layer 6 in the drawing) where the number of lead-out portions is small, the effective connection area is small, and the current density per one internal electrode layer is high. Moreover, since the connection portion between the internal electrode 2 and the external electrode 4 is very thin and close to a wire connection, in some cases, before reaching the design value of the surge current withstanding capability, the internal electrode layer side with a small number of lead-out portions is provided. The connection part may be damaged by surge current. This results in low reliability as a voltage nonlinear resistor.

The laminated voltage non-linear resistor of the present invention has been proposed in order to solve the problems of the prior art as described above, and its purpose is to obtain a surge current withstand value which is a value during actual use. Is a value designed in advance, and it is to provide a highly reliable laminated voltage nonlinear resistor that can be used safely.

[0008]

In order to solve the above-mentioned problems of the prior art, in the present invention, a plurality of internal electrodes are alternately exposed at their ends in a varistor composition material having a varistor function. In the laminated voltage non-linear resistor having the laminated body thus laminated and the external electrode connected to the exposed end of the internal electrode, the laminated body has a total number of internal electrodes that is always an even number. It is characterized by being provided as follows.

[0009]

The operation of the present invention having the above construction is as follows. That is, in the present invention, since the total number of laminated internal electrodes is an even number in the laminated body constituting the laminated voltage non-linear resistor, the same number of lead-out portions that are alternately exposed at the opposite end portions in the two directions. Become. As a result, the same number of internal electrodes are connected to the two opposing external electrodes. As a result, the effective connection area of each external electrode with the internal electrode becomes equal, and the current density per layer of the internal electrode becomes a constant value. Therefore,
Unlike the conventional case, there is no problem that the surge current withstand value becomes lower than the design value due to the deviation of the current density, and it is possible to use safely along the design value and the reliability is high.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a laminated voltage non-linear resistor according to the present invention will be specifically described below with reference to the drawings.
The same members as those in the conventional example are designated by the same reference numerals, and the description thereof will be omitted.

As shown in FIG. 1, in the laminated voltage nonlinear resistor of this embodiment, the ceramic green sheet 1 is used.
The laminated body 3 formed by alternately laminating the internal electrodes 2 and the internal electrodes 2 is configured as follows. That is, in the laminated body 3, the internal electrodes 2 having a total number of laminated layers are laminated and pressure-bonded so that the lead-out portions 5 are alternately opposite sides, and are sintered and integrated. Then, each lead-out portion 5 exposed in two opposite directions
Are external electrodes 4 that electrically connect the internal electrodes 2 in parallel.
Is connected.

The operation and effect of this embodiment having the above-mentioned structure are as follows. That is, by setting the number of laminated internal electrodes 2 to be an even number, the first electrode layer 6 and the second electrode layer 7 are laminated in the same number of layers, respectively, and the number of derived portions is the same. Therefore, the first electrode layer 6 and the second electrode layer 6
The electrode layers 7 have the same effective connection area, and the current densities per inner electrode layer are all the same. As a result, when the surge current is less than or equal to the design value of the surge current withstand capability, the connection between one of the inner electrode 2 and the outer electrode 4 is not destroyed by the surge current.

Subsequently, based on the above-mentioned steps, a laminated voltage non-linear resistor (invention product P) in which the number of laminated internal electrodes is an even number is manufactured according to the present invention, and the number of laminated internal electrodes is increased. An odd-numbered laminated voltage nonlinear resistor (conventional product Q) was manufactured. First, for both the product P of the present invention and the conventional product Q,
The outer diameter was 2.5 mm on the lead-out side, which is the short side, 3.2 mm on the long side, and 1.3 mm in thickness. Further, in the product P of the present invention, the number of stacked internal electrodes was three, 2, 4, and 6, and in the conventional product Q, three, 1, 3, and 5. By setting the thickness of the ceramic layer (hereinafter referred to as an effective ceramic layer) between the opposing internal electrodes to 70 μm, and adjusting the thicknesses of the ceramic layers above the uppermost internal electrode and below the lowermost internal electrode. The outer diameter dimensions of the laminated voltage nonlinear resistors were matched.

With respect to the product P of the present invention and the product Q of the related art manufactured as described above, the surge current withstanding current waveform (8 × 20 μsec) was examined with respect to the number of laminated internal electrodes. As a result, as shown in FIG. 2, in the product P of the present invention in which the number of laminated internal electrodes is an even number, the surge voltage withstand is increased with respect to the increase in the number of laminated layers as compared with the conventional product Q in which the number of laminated layers is an odd number. It is big. This is based on the surge voltage withstanding number when the number of laminated layers is 2, and in the product P of the present invention, the number of laminated layers and the surge current withstand amount are in a direct proportion of 1: 1. However, the increase in the surge current withstand value is low with respect to the increase. In particular, the surge current withstand value of the product P of the present invention in which the number of laminated layers is 4 is larger than that of the conventional product Q in which the number of laminated layers is 5, which is larger than this.

From this, it is understood that when the conventional product Q is designed to have a surge current withstanding capacity only by the number of laminated internal electrodes, the breakdown appears at a value lower than this value. On the other hand, in the product P of the present invention, by configuring the total number of laminated internal electrodes to be an even number at all, the number of laminated layers corresponds to the surge current withstand ratio of 1: 1. In addition to being able to achieve this, the designed value and the actual surge current withstand value are in agreement. Therefore, it is possible to use the design value reliably and safely, and it is possible to provide a laminated voltage nonlinear resistor having excellent reliability.

The present invention is not limited to the above embodiment, and the material, shape, size, etc. of each member can be appropriately changed. For example, the shape of the internal electrode is not limited to a rectangular shape, and may be a trapezoid, a triangle or the like as long as the margin can be secured. However, in order to secure the connection length between the internal electrode and the external electrode, the width of the connection portion of the internal electrode with the external electrode is the same as or wider than the width of the end of the internal electrode on the side not exposed,
In addition, it is necessary to secure a margin portion, and in this case, a trapezoidal shape, a triangular shape, a convex shape, or the like may be used.

Also, the manufacturing process is not limited to that shown in the above embodiment, but as long as it is configured so that the total number of laminated internal electrodes is an even number as in the present invention, how is it made? It may be manufactured.

In the above-mentioned embodiments, the explanation has been made based on the internal electrodes, but when the number of laminated internal electrodes is even, the effective ceramic layer sandwiched between the opposing internal electrodes is odd. Therefore, in the present invention, by configuring the effective ceramic layer to always be an odd number,
This is the same as setting the total number of laminated internal electrodes to an even number, and the same operation and effect are obtained.

[0019]

As described above, according to the present invention, by configuring the total number of laminated internal electrodes to be an even number, the surge current withstand value matches the value during actual use and the design value. It is possible to provide a laminated voltage nonlinear resistor that can be used safely and has excellent reliability.

[Brief description of drawings]

FIG. 1 is a side sectional view showing an embodiment of a laminated voltage nonlinear resistor according to the present invention.

FIG. 2 is a graph showing experimental data comparing the surge current withstand capability of a conventional product and a product of the present invention of a laminated voltage non-linear resistor.

FIG. 3 is a side sectional view showing a general laminated voltage non-linear resistor.

[Explanation of symbols]

 1 Ceramic Green Sheet 2 Internal Electrode 3 Laminated Body 4 External Electrode 5 Lead-out Part 6 First Electrode Layer 7 Second Electrode Layer

Claims (1)

[Claims] 1. A laminated body in which a plurality of internal electrodes are laminated in a varistor composition material having a varistor function so that the ends are alternately exposed, and an external electrode connected to the exposed ends of the internal electrodes. In the laminated voltage non-linear resistor having the above-mentioned, the laminated body is provided so that the total number of laminated internal electrodes is always an even number.