JPH05205908A - Manufacture of lamination type non-linear voltage resistor - Google Patents

Abstract

PURPOSE:To provide a lamination type non-linear voltage resistor in which the main cause for generation of delamination is eliminated and dampproof characteristics can be improved. CONSTITUTION:A margin part 2 is provided on three sides of the surface, and a slurry 4, having the composition same as a sheet 1, is printed in the thickness same as the inner electrode 3 on the margin part 2 of the ceramic green sheet 1 on which an inner electrode 3 is formed extending to the outer circumference of the side where the margin part 2 is not provided. Then, a plurality of ceramic green sheets 1 are press-bonded by lamination, integrally formed by sintering, and a laminated body, having no stepped part on the inner-electrode-3-formed part and the margin part 2, 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 method of manufacturing a laminated non-linear resistor (hereinafter referred to as a varistor) having an improved laminated structure.

[0002]

2. Description of the Related Art A conventional laminated varistor has a varistor composition in which one side is extended to the outer periphery and an internal electrode 20 is provided on the surface and a margin portion 21 is provided on the other three sides as shown in FIG. Ceramic green sheet 2
6, a plurality of the ceramic green sheets 22 are laminated and pressure-bonded so that one side extending to the outer periphery of the internal electrode 20 is alternately on the opposite side as shown in FIG. 23, and has a structure in which one side extending to the outer periphery of the internal electrode 20, that is, a portion other than the external extraction electrode portion 24 of the internal electrode is surrounded by the laminated body 23.

Such a laminated varistor has a high surge resistance and can be surface-mounted on various circuit boards, so that it has a high practical value, and it is considered that the demand thereof will further increase in the future, and the quality is stabilized. Is desired.

Therefore, in the laminated varistor having such a structure, the number of laminated layers must be increased in order to improve the surge resistance, but in the case of the laminated body 23, the internal electrodes 20 are to be formed. Since the margin portion 21 has a thickness difference corresponding to the thickness of the internal electrode 20, a step 25 is formed as shown in FIG. 7, and the step 25 increases in proportion to the number of laminated ceramic green sheets 22. As a result, the pressure applied during lamination and compression of the ceramic green sheets differs between the internal electrode 20 forming portion and the margin portion, and due to the difference in shrinkage strain during sintering, delamination occurs between the varistor composition and the internal electrode 20. (Delamination) occurs, which results in having a factor that causes deterioration of moisture resistance characteristics.

[0005]

As described above, the laminated varistor having the above-described structure is caused by the difference in thickness between the internal electrode forming portion and the margin portion caused by the lamination of the ceramic green sheets having the internal electrodes formed thereon. And had the drawback of causing delamination.

An object of the present invention is to provide a method of manufacturing a laminated voltage non-linear resistor which does not cause delamination even if the number of laminated layers is increased and exhibits stable characteristics.

[0007]

According to the method of manufacturing a laminated voltage non-linear resistor according to the present invention, margins are provided on three sides of one surface, and the margins are not provided to extend to the outer periphery of one side and After printing a slurry having the same composition as the sheet with the same thickness as the internal electrode on the margin portion of the ceramic green sheet on which the electrode is formed, one side extending to the outer periphery of the internal electrode is alternately opposite sides. The external electrodes are formed on both side surfaces of the laminated body obtained by laminating a plurality of the ceramic green sheets and sintering and integrating them.

Further, a margin is provided on three sides of both sides, and the margin is not provided on the opposite sides of the two sides. It also includes one in which a slurry of the same component is printed to the same thickness as the internal electrodes, and then a plurality of the ceramic green sheets and the ceramic green sheets without forming the internal electrodes are alternately laminated and sintered to obtain a laminated body. .

[0009]

[Function] The margin of the surface of the ceramic green sheet where the internal electrode is not formed is printed with the slurry of the same component as the ceramic green sheet with the same thickness as the internal electrode. In addition, there is no step between the internal electrode formation portion and the margin portion, the delamination generation factor can be eliminated, and it has an effect of greatly contributing to high reliability.

[0010]

EXAMPLES Examples of the present invention will be described below.

As shown in FIG. 2, zinc oxide is used as a main component having a varistor function after sintering, bismuth oxide as an additive, and cobalt oxide, manganese oxide, nickel oxide, chromium oxide, magnesium oxide, and oxides. 2 out of lead, aluminum oxide, titanium oxide, ammonium oxide, barium oxide, silicon oxide, boron oxide, etc.
One kind or three or more kinds are added, mixed in a ball mill, dried and calcined at 600 to 950 ° C., then pulverized and dispersed in a solvent together with an organic binder to form a slurry.

Next, this is 2 by the doctor blade method.
A uniform ceramic green sheet 1 having a thickness of 0 μm to 100 μm is formed. Then, next, a margin portion 2 is provided on three sides of one surface of the ceramic green sheet 1 and is extended to the outer periphery of one side where the margin portion 2 is not provided, gold, platinum, palladium, silver, copper, nickel, or these. Of the two or more of the above-mentioned alloys are screen-printed to form an internal electrode 3, and a slurry 4 having the same composition as that of the sheet 1 is printed on the margin 2 to the same thickness as the internal electrode 3. After that, as shown in FIG. 3, a plurality of the ceramic green sheets 1 are laminated and pressure-bonded so that one side extending to the outer periphery of the internal electrode 3 is alternately on the other side, and thereafter, as shown in FIG. 0.5 ~ 1250 ℃
A silver paste is applied to both side surfaces of the laminated body 5 obtained by sintering and integration for 8 hours where the internal electrodes 3 are exposed, and the temperature is 450 to 850 ° C.
The external electrode 6 is formed by baking.

According to the method of manufacturing the laminated voltage non-linear resistor having the above-described structure, the ceramic green sheet 1 has the same thickness as the internal electrode 3 in the margin portion 2 where the internal electrode 3 is not formed. Since the slurry 4 having the same composition as that of the green sheet 1 is printed, even if the number of laminated layers is increased for the purpose of improving the surge resistance, there is no step in the thickness of the internal electrode 3 and the margin portion 2, and the delamination does not occur. It is possible to obtain a laminated type voltage non-linear resistor having excellent moisture resistance and excellent reliability, which can eliminate the cause of occurrence of the above.

Next, a characteristic comparison between the laminated voltage non-linear resistors obtained by the present invention and the conventional example will be described. (Invention A) The slurry to be printed on the ceramic green sheet and the margin is made of ZnO (95.5 mol%), C
oO (1 mol%), MnO (1 mol%), Cr ₂ O
₃ (1 mol%), Sb ₂ O ₃ (1 mol%), Bi ₂ O ₃
The composition was (0.5 mol%), and the silver-palladium alloy was used as the internal electrode, and the ceramic green sheets were laminated by the means described in the above example.

(Prior Art Example B) The composition ratio of the ceramic green sheets, the internal electrode material and the number of laminated ceramic green sheets, etc. were manufactured by the same means as in the invention A except that the slurry was printed in the margin.

Moisture resistance test of the invention A and the conventional example B (DC
Apply 16V, 90 ~ 98% RH, from 30 ℃ to 65
The process of raising the temperature to 65 ° C over 3 hours, keeping at 65 ° C for 6 hours, and then lowering the temperature from 65 ° C to 30 ° C over 3 hours is a cycle, and this cycle is repeated for 1000 hours. As a result of investigating the occurrence rate of deterioration of ΔV by 10% or more after that, as shown in Table 1, the invention A is the conventional example B.
The moisture resistance was significantly better than that of

The sample of the present invention A and the conventional example B were both 1
It is 10,000.

[0018]

[Table 1]

In the above embodiment, the case where a plurality of ceramic green sheets having the internal electrodes formed on one surface thereof are laminated has been described as an example. However, as shown in FIG. 4, margin portions 7 are provided on three sides of both surfaces. Provided This margin portion 7 is not provided and extends to the outer periphery of one side opposite between both surfaces and the internal electrode 8 is provided.
Using the ceramic green sheet 9 formed on both sides,
After printing the slurry 10 having the same composition as the sheet 9 in the same thickness as the internal electrodes 8 on the margins 7 formed on both sides, a plurality of the ceramic green sheets 9 and the ceramic green sheets 11 without the internal electrodes are alternately formed. The same effect can be obtained by laminating the sheets, then pressing and then sintering and integrating them by the same means as described in the above embodiment to obtain a laminated body.

[0020]

According to the present invention, the occurrence of delamination can be prevented without forming a step between the internal electrode forming portion and the margin portion forming position forming the laminate.
It is possible to provide a method for manufacturing a laminated voltage non-linear resistor that can obtain a highly reliable laminated voltage non-linear resistor having excellent moisture resistance.

[Brief description of drawings]

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

FIG. 2 is a perspective view showing a ceramic green sheet on which an internal electrode is being manufactured according to an embodiment of the present invention.

FIG. 3 is a cross-sectional view showing a pre-sintering laminate in the process of being manufactured according to an example of the present invention.

FIG. 4 is a perspective view showing a laminated state of ceramic green sheets in the process of being manufactured according to another embodiment of the present invention.

FIG. 5 is a cross-sectional view showing a ceramic green sheet on which internal electrodes are being manufactured according to a conventional example.

FIG. 6 is a cross-sectional view showing a laminate in the process of being manufactured according to a conventional example.

FIG. 7 is an enlarged cross-sectional view of the portion a in FIG.

[Explanation of symbols]

 1 Ceramic Green Sheet 2 Margin Part 3 Internal Electrode 4 Slurry 5 Laminated Body 6 External Electrode 7 Margin Part 8 Internal Electrode 9 Ceramic Green Sheet 10 Slurry 11 Ceramic Green Sheet

Claims (2)

[Claims] 1. A step of forming a margin part on three sides of one surface of a ceramic green sheet and extending to the outer periphery of one side without the margin part to form an internal electrode, and a slurry of the same component as the sheet in the margin part. A step of printing the same thickness as the internal electrode, and one side extending to the outer periphery of the internal electrode is alternately located on the opposite side, and a plurality of the ceramic green sheets are laminated without the internal electrodes contacting each other. Then, a laminated voltage non-linear resistor is manufactured by sequentially performing a step of obtaining a laminated body integrally sintered and a step of forming external electrodes on both side surfaces of the laminated body where the internal electrodes are exposed. Method. 2. A step of forming an internal electrode by extending a margin part on both sides of a ceramic green sheet and extending to the outer periphery of one side opposite to each other without the margin part, and forming the internal electrode on the margin part. A step of printing a slurry having the same composition as the sheet to the same thickness as the internal electrodes, and a step of alternately laminating a plurality of the ceramic green sheets and ceramic green sheets not forming the internal electrodes to obtain a laminated body which is sintered and integrated. And a step of sequentially forming external electrodes on both side surfaces of the laminated body where the internal electrodes are exposed, the method of manufacturing a laminated voltage non-linear resistor.