JPH0669003A - Laminated voltage dependent nonlinear resistor element and manufacture thereof - Google Patents

Abstract

PURPOSE:To avoid the accelerated deterioration in the varristor characteristics when a chip varristor is continuously impressed with DC voltage at high temperature and humidity. CONSTITUTION:An outer protective film 3 whose whole surface excluding an outer electrode 2 is covered with an insulating sheet ms formed. Through these procedures, any moisture content at high temperature and humidity can be prevented from permeating into the elements of a chip varristor thereby avoiding the accelerated deterioration in the varristor characteristics.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a laminated voltage non-linear resistance element and a method for manufacturing the same, and more particularly to a laminated non-linear resistance element in which external protective films are formed on both upper and lower sides of a chip component body and a method for manufacturing the same.

[0002]

2. Description of the Related Art In a laminated type voltage non-linear resistance element (hereinafter referred to as a chip varistor), a ceramic sheet is punched into an appropriate size as shown in FIG. Are screen-printed, and an appropriate number of the ceramic sheets 35 and 36 on which the internal electrodes are printed are laminated by thermocompression and baked to form the external electrodes 3.
A chip varistor having the structure shown in the drawing can be obtained by applying and baking 1, 32. FIG. 3A is a perspective view of the chip varistor, and FIG.
(C) is a sectional view taken along the (A) C-C ₁ line, with D-D ₁ line. (For example, Japanese Patent Publication No. 58-23921).

[0003]

This conventional chip varistor has the same condition as the elements of the chip varistor are exposed on both the upper and lower sides as shown in FIG. 3, and the DC voltage is applied to the chip varistor in high temperature and high humidity. When the voltage is applied, the rising voltage changes, the leakage current increases, and the characteristics of the varistor gradually deteriorate. This causes a problem that moisture due to high temperature and high humidity permeates into the inside of the chip varistor, and the deterioration of the element is accelerated.

It is an object of the present invention to provide a laminated type voltage non-linear resistance element which eliminates the conventional defects and has improved varistor characteristics at high temperature and high humidity, and a manufacturing method thereof.

[0005]

A chip varistor of the present invention comprises a stack of ceramic sheets having internal electrodes printed thereon,
An external protective film is formed by covering the entire surface of the stacked units with a glass sheet having an insulating property except the external electrodes with a ceramic sheet. As a result, it is possible to prevent the moisture in the high temperature and high humidity from penetrating into the inside of the chip varistor, and to prevent the deterioration of the element from being accelerated by the moisture.

[0006]

The present invention will be described below with reference to the drawings.

[0007] Figure 1 is a perspective view and A-A ₁ and B-B ₁ cross-sectional view of the chip varistor according to an embodiment of the present invention.

First, as in the conventional method, an appropriate number of ceramic sheets 7 and 8 on which the internal electrodes 5 and 6 are printed are stacked and stacked, and the stacked units are subjected to the first thermocompression bonding so that the internal electrodes are staggered. Cut it into a stick-shaped unit as shown in Fig. 2 in the direction not exposed. Next, a chiller-like mixture having an insulating property such as glass is formed into a film thicker than the ceramic sheet on which electrodes are formed by the doctor blade method etc., and the unit is covered with the thick film to obtain a unit covered with a protective film. . Then, the final second thermocompression bonding is performed,
Next, the internal electrodes 5 and 6 are cut and fired so that they are exposed alternately. Finally, the external electrodes 1 and 2 are applied so as to overlap the external protective films 3, 4, 9, and 10 and baked to obtain a chip varistor as shown in FIG. 1 (B) and 1 (C) show (A) as a line segment A-
Is a sectional view taken along with A _1, B-B _1.

Next, a test conducted to confirm the effect of this embodiment will be shown. At a temperature of 80 ° C and a humidity of 95%, a DC voltage that is 80% of the varistor voltage indicating the rising voltage is 10
When continuously applied for 00 hours, as shown in Table 1, the sample without the external protective film has a large change rate of the varistor voltage and the leakage current also has a large increase. Is small and the increase in leakage current is small. The characteristics for high temperature and high humidity are improved.

[0010]

[0011]

As described above, the present invention has the result that the varistor characteristic with respect to high temperature and high humidity is improved because the sheet of the external protective film having an insulating property such as glass is formed on the entire surface excluding the external electrodes.

[Brief description of drawings]

FIG. 1 is a perspective view and an AA ₁ and BB ₁ line sectional view of an embodiment of the present invention.

FIG. 2 is a perspective view of a stick-shaped component in a partial process for explaining the manufacturing method according to the embodiment of the present invention.

FIG. 3 is a perspective view of an example of a conventional laminated type voltage non-linear resistance element and a cross-sectional view taken along line AA _{1 and} line BB ₁ .

[Explanation of symbols]

 1, 2, 31, 32 External electrode 3, 4, 9, 10 External protective film 5, 6, 21, 33, 34 Internal electrode 7, 8, 22, 35, 36 Ceramic sheet

Claims (2)

[Claims] 1. A ceramic sheet laminate obtained by laminating and sintering ceramic sheets printed with internal electrodes, an insulating protective film such as glass covering the upper and lower side surfaces of the ceramic sheet laminate except the external electrode forming surface, A laminated voltage non-linear resistance element having an external electrode formed on an external electrode formation surface. 2. A step of stacking a suitable number of ceramic sheets on which internal electrodes are printed, stacking them by thermocompression bonding, and cutting them into stick-shaped units in a direction in which the internal electrodes are not exposed alternately, and a slurry having an insulating property such as glass. Forming a thick film by a doctor blade method etc. to form a film thicker than the ceramic sheet, a step of thermocompression covering the entire stick-shaped unit with the film formation, and cutting at positions where the electrodes are alternately exposed And a step of applying an electrode material to the exposed surface of the internal electrode so as to overlap the external protective film and firing the electrode material to form an external electrode. Method.