JPS6015126B2 - Manufacturing method of voltage nonlinear resistor element - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for manufacturing a voltage nonlinear resistor element containing Zn○ as a main component.

Conventionally, the side insulation methods for this type of voltage nonlinear resistor element (hereinafter referred to as an element) mainly composed of Zn○ include applying an epoxy-based organic material to the side surface of the element after firing to insulate it, or applying insulation before firing the element. Various inorganic compounds were applied to the sides of the device and fired, and after firing, an insulating coating was formed that became a glassy or crystalline insulator for insulation.

However, the former method has the disadvantage that the adhesion between the applied epoxy-based organic material and the element body is poor, and as a result, moisture is adsorbed to the element, resulting in significant deterioration of characteristics and weakening of short-wave tail resistance.

Furthermore, since there is a difference in thermal expansion between the element body and the epoxy resin, there is a drawback that the epoxy resin coated on the side surfaces of the element cracks due to thermal shock, causing deterioration. In the latter method, it is necessary to match the shrinkage rates of the element body and the side insulating material during firing. For this purpose, the compression molded element is first fired to shrink it to some extent, and then an inorganic compound or a mixture thereof is applied to the side surface of the element after the first firing.
Main firing is performed to form an inorganic insulating side surface coating. In this case, it is necessary to perform the baking twice. Furthermore, during firing B
i203 evaporates from the element body.

This causes non-uniformity in the concentration of the Bi203 grain boundary layer, which is responsible for the nonlinearity of the device, and liquid phase condensation due to the liquid phase of Bj203 causes variations in the grain growth rate of the Zn○ particles, reducing piezoelectric nonlinearity. There are drawbacks to doing so. Furthermore, both methods have the disadvantage that considerable skill and equipment are required in order to make the coating film uniform to the required thickness. In view of the above-mentioned drawbacks, an object of the present invention is to form an insulating film having dense and uniform crystal grains and having good adhesion to the device body, and to reduce deterioration of device characteristics.
It is an object of the present invention to provide a method for manufacturing a voltage nonlinear resistor element in which voltage nonlinear characteristics do not deteriorate.

According to the present invention, the above object is achieved by placing an oxide of antimony and an oxide of bismuth in a container used for firing, and placing a molded body mainly composed of Zn○ in the same container and firing them at the same time. .

An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 shows an embodiment to which the method of manufacturing a voltage nonlinear resistor element of the present invention is applied.

In FIG. 1, a pedestal 14 made of a heat-resistant ceramic material is placed on the bottom of an alumina sheath (firing container) 12.

On this pedestal 14, with a layer of bedding powder 16 interposed therebetween, a Qin body 18 which is compression-molded and whose main component is Zn◯ is placed. Dungeon powder 16
This prevents the pedestal 14 and the element body 18 from welding. Further, a side insulation coating is formed on the element body 18 on the inner surface of the sheath 12,
Coating agent 20 for preventing evaporation of Bi203 from the element body
is coated. The top of the sheath 12 is provided with a lid 22 that is homogeneous to the sheath 12. The material of the pedestal 14 is preferably an alumina or zinc oxide sintering plate, and in particular, a zinc oxide sintered twill plate is preferable since it is of the same quality as the main component of the element and does not impair the characteristics of the sintered element.

The bed powder 16 is made of alumina or ZnQ element powder or Zn.
○ Powder made by calcining and crushing the element is used. Znq
Similar or identical components of the element are required more strongly than in the case of the pedestal. Note that if the pedestal 14 is made of the same material as the material 18, the powder 16 may be omitted. Also, coating agent 2
It may be applied to a part or the entire surface of the inner surface of the coating material 12 and the bottom surface of the lid 22, or another material may be interposed between the sheath and the coating agent. A coating agent may be placed nearby. A method for manufacturing the voltage nonlinear resistor element of the present invention will be described below.

First, the element body 18 is made of Zn0 (91% by weight) with SQ03,B
i203, Co203, Cr203, Mn02, Si0
Two equal parts (9% by weight) of the mixture were added, thoroughly mixed, and then compression molded into a suitable shape. For example, it is made into a cylindrical shape with a diameter of 40 mm and a thickness of about 30 mm. The coating agent 20 uses a slurry obtained by weighing Sb203 and Bi203 as starting materials as shown in the table below, adding an appropriate amount of water, and sufficiently wet-mixing.

The coating agent 20 thus prepared is applied to the inner wall surface of the firing container shown in FIG. 1 and dried (approximately 2 coats are applied to the container having an internal volume of 200').

Thereafter, the element body 18 containing Zn○ as a main component is placed in the sheath 12 and covered with a lid 22 to make it almost airtight. 100 in this sealed state
0:00 to 1400:00 C (from the point of view of the electrical characteristics of the element, 11
000°C to 1300°C is preferable. ) When fired in the temperature range of A high-resistance insulating film is formed on the surface of the element body 18 through a gas phase reaction with Zn○, additive mixture, etc. In the above solid and gas phase reactions, Sb20 coated inside the container
3. Among Bi203, Sb203 is 57000 and SQ0
It transforms into 4 and begins to sublimate at around 920°C, and becomes extremely active at temperatures above 100,000°C.

Also, Bi203 melts at 82,000 and the temperature inside the firing furnace is 100.
000 or more, the atmosphere is filled with highly concentrated seed molecules of antimony oxide and bismuth oxide. On the other hand, element 18 is 800
In the temperature range from q0 to 100,000, it shrinks by about 40% by volume, and in addition to Zn○, Zn2Si04, pyrochlore, Zn2,
A crystal layer of 33Sb〇, 6704, Bi203, 14Bj203-Cr203, etc. is formed. Bi on the surface of the element
Although 203 begins to evaporate as the heating temperature rises, the amount of evaporation is considerably suppressed by the atmosphere of Bi203 generated in the firing furnace. Further, SQ03 in the atmosphere reacts with the element body, and spots Z~ and spots Sbo, 6704 are formed on the surface. At this time, Bi203 in the atmosphere or in the element body promotes the reaction between the element body and SQ03 in the atmosphere. These compounds are bound together with the elementary bodies. In this way, a voltage nonlinear resistor element having a side insulating coating with dense and uniform crystal grains is manufactured. FIG. 2 shows the results of examining, using an X-ray microanalyzer, the condition of an insulating film formed on the surface of an element fired using a coating agent consisting of Sb203 and Bi203. Figure A shows the case where 6$Q03-40Bi203 is applied, 1 is the secondary electron image, 0, m, and W are Sb, respectively.
This is a characteristic X-ray image of Zn and Bi.

From these images, it can be seen that there is a Bi-rich layer in the insulating film. B in the same figure shows the case where No. 8 b203-20Bi203 is applied, 1 is the secondary electron image, and B, m, and W are Sb.
, Zn, and Bi. Although not shown here, it is clear from the X-ray diffraction diagram of the coating shown in FIG.
4), with a small amount of Bj203 mixed therein.
Since this spinel solidified Co, Mn, and Cr present in the element, it was confirmed that it was formed by sufficiently reacting with the spinel body 18 formed on the surface during firing. Although not shown in the figure, it was confirmed from the characteristic x-ray image of other X-ray microanalyzers that Co, Mn, Cr, Si, etc. were dissolved in solid solution. FIG. 3 shows a chemical analysis of Bi203 in the element obtained by firing the element body 18. As shown in the figure, by applying Bi203, Bi203 from the element body is
It can be seen that scattering of 203 is suppressed. FIG. 4 shows the electrical characteristics of devices manufactured in a firing furnace with different mixing ratios of SQ03 and Bi203 to be applied.

In the figure, 0 indicates 0.1mAQ, mA, △ indicates V2,5KA
/V, mA, and X indicate the discharge capacity (4×10 ms twice). As the amount of Bj203 decreases, it becomes 0.1mA.
Q, mA decreases, V2,5KA/V, mA increases,
It can be seen that although the discharge withstand capacity decreases, it suddenly changes when Bi203 becomes less than 20%. FIG. 5 is a diagram showing the relationship between the amount of Bi203 in the firing container and the thickness of the insulating layer.

A indicates the thickness of an insulating layer formed with a coating agent of Sb203 and Bi203, and B indicates a thickness of an insulating layer formed with a coating agent of only Sb203. From the diagram Bi2
As the amount of 03 increases, the thickness of the insulating layer increases. Especially B
i203 increases linearly up to 2 plates. However, when the concentration exceeds 0%), an Sb-Bi-Zn-○ oxide layer is formed on the outside of the Z~, 3bubo, and nail04 phases, and Zn2
, Spot Sb. , 6704 phase (spinel) formation reaction
203 will no longer be involved. Figure 6 shows the process of forming an insulating layer in which the Bi203 content is up to 25%.
Bj 203 is completely evaporated from the coating agent 20, and Bj 203 is suppressed from evaporating from the element body 18. In addition, Bj203 promotes the formation of spinel phase 24 formed by a gas phase reaction between Sb203 and Zn○ from element body 18. FIG. 7 shows the process of forming an insulating layer when Bj203 exceeds 30%.

Since Bi203 is in excess, Bi203 becomes saturated and Sb-Bi-Zn-0 based oxide 26 is formed on top of the spinel phase 24.
, and does not contribute to the formation of the spinel phase. Also, coating agent 2 Kawakoha B et al. 03 remains. According to this embodiment, Sb
By applying a mixture of 203 and Bi203 as a coating agent to a container containing the element body, and baking the Zn○ element body in an atmosphere of SQ03 and Bi203 to manufacture an element.
Since Bi203 evaporates from the nO substance and is thick, it is effective in manufacturing a voltage nonlinear resistor element having nonlinear voltage-current characteristics with good electrical characteristics such as discharge withstand capacity.

Since the Bi203 atmosphere promotes the formation of an insulator, it has the effect of easily forming a high-resistance insulating layer on the side surface of the device within the device firing temperature range. This insulating layer has the effect that the electrical properties of the device are superior to those coated with epoxy resin, and it is possible to manufacture a device with properties equivalent to those obtained by applying an inorganic side surface agent and firing. Also, Bi20 from Zn○ element body
In order to suppress scattering of 3, it is effective to manufacture a homogeneous element. As is clear from the above description, according to the present invention,
By firing the Zn* element in a mixed atmosphere of antimony oxide and bismuth oxide, an insulating layer with fine and uniform crystal grains and good adhesion to the element body is formed, and the element It is possible to obtain a voltage nonlinear resistor element that exhibits little characteristic deterioration, increases voltage nonlinearity, and further improves other electrical characteristics.

[Brief explanation of drawings]

Fig. 1 is an explanatory diagram to which a method for manufacturing a voltage non-linear resistor element according to an embodiment of the present invention is applied, Fig. 2 shows the state of an insulating layer formed by an X-ray microanalyzer, and Fig. A shows a 6 eaves b.
In the case of 203-4 clothes i203, 1 is the secondary electron image, b,
m, W are the characteristics x diagram of Sb, Zn, Bi, respectively, B is the case of 8 eaves Q03-20Bj203, 1 is the secondary electron image, 0, m, W are the characteristics X of Sb, Zn, Bi Line image, Figure 3 shows the amount of mixture of Sb203 and Bi203, and the B in the element.
i203 weight loss relationship diagram, Figure 4 is Sb203 and Bi20
Relationship diagram between the change in the mixing ratio in No. 3 and the electrical characteristics of the element, No. 5
The figure shows the relationship between the amount of Bj203 in the firing container and the thickness of the insulating layer. Figure 6 shows the process of forming an insulating layer when Bj203 is 20% or less. Figure 7 shows the insulating layer formation process when Bj203 is 30% or less. Figure 8 is an X-ray diffraction diagram of the film, showing the process of forming an insulating layer in the case where the concentration is higher than %. 12... Sheath, 18... Element, 20... Coating agent, 2
2... Lid. Figure 1 Figure 2 Figure 3 Figure 8 Figure 2 Figure 4 Figure 5 Figure 6 Figure 7

Claims (1)

[Claims] 1. When firing a voltage nonlinear resistor containing zinc oxide, antimony oxide and bismuth oxide are placed in a container, and a side insulating film is formed by a gas-solid phase reaction at the same time as the firing. A method for manufacturing a voltage nonlinear resistor element characterized by: