JPH0775201B2 - Method for manufacturing voltage non-linear resistor - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a method for manufacturing a voltage non-linear resistor containing zinc oxide as a main component, and in particular, it exerts an adverse effect on water of an element that affects electrical characteristics. The present invention relates to a method of manufacturing a voltage non-linear resistor that can be effectively prevented. Here, the element body for a voltage non-linear resistor means a fired body for a voltage non-linear resistor before forming electrodes.

(Prior Art) Conventionally, a voltage non-linear resistor is prepared by mixing zinc oxide powder as a main component and various metal oxides and then granulating the mixture with a spray dryer or the like. Further, main firing is performed to first form an element body for a voltage non-linear resistor, and then, a polishing process is performed to make the element body to a prescribed thickness and to flatten both end surfaces, and then to flatten it. It is manufactured by performing a step of spraying an electrode material such as aluminum on both end surfaces of the base body.

(Problems to be Solved by the Invention) By the way, in the above polishing step, a liquid abrasive (lapping agent) is used for polishing, for example, with a lapping machine. For example, if grinding oil or the like is used, it takes time to remove the grinding oil. Therefore, grinding is performed using water as a grinding liquid. However, when water is used, the time required to form a specified dimension is relatively long, and therefore water adversely affects the element body, and the electric power is reduced. Characteristics, especially the non-linear index of the voltage non-linear resistor is deteriorated.

The object of the present invention is to solve the above-mentioned problems, to increase the stable electric characteristics, in particular, to increase the voltage in the minute current region of the voltage-current characteristics, to reduce the leakage current, and at the same time, in the nonlinear portion of the voltage-current characteristics. Therefore, it is an object of the present invention to provide a method of manufacturing a voltage non-linear resistor having a large non-linear index.

(Means for Solving the Problems) In the present invention, the surface of the electrode formation region of the element body is polished before the electrode is formed on the element body for the voltage non-linear resistor whose main component is zinc oxide. The method for producing a voltage non-linear resistor is characterized in that the contact time of the surface of the element body with the grinding water during polishing of the surface of the element body is within 10 minutes.

(Operation) In the present invention, when the element body for the voltage non-linear resistor is polished by using water as the grinding liquid, the contact time between the element surface and water is set to 10 minutes or less. It is possible to polish to a specified size while minimizing the adverse effect of water.

The procedure for manufacturing a voltage nonlinear resistor by applying the present invention will be described below.

Additive consisting of a main material of zinc oxide adjusted to a predetermined particle size and a metal oxide such as bismuth oxide, cobalt oxide, manganese oxide, antimony oxide, chromium oxide, silicon oxide, nickel oxide adjusted to a predetermined particle size, and preferably silver A predetermined amount of bismuth borosilicate glass containing is mixed. Next, a predetermined amount of an aqueous solution of polyvinyl alcohol and a predetermined amount of an aluminum nitrate solution as a source of aluminum oxide are mixed with these raw material powders. This mixing operation preferably uses an emulsifier.

Next, vacuum degassing is preferably performed at a vacuum degree of 200 mmHg or less to obtain a mixed sludge. The water content of the mixed slurry is preferably about 30 to 35 wt%, and the viscosity of the mixed slurry is preferably 100 cP ± 50.

Next, the obtained mixed sludge is supplied to a spray dryer to granulate a granulated powder having an average particle size of 100 μm ± 50 and a water content of 0.5 to 2.0 wt%, more preferably 1.0 to 1.5 wt%.

Next, the granulated powder obtained is subjected to a molding pressure of 80 in the molding step.
It is molded into a specified shape under 0 to 1000 kg / cm ² . Then, the molded body is pre-baked at a temperature rising / falling rate of 50 to 70 ° C./hr at 800 to 1000 ° C. and a holding time of 1 to 5 hours to scatter and remove the binder.

Next, an insulating coating layer is formed on the side surface of the calcined body that has been calcined. The insulating coating layer is specifically made of an oxide paste in which a predetermined amount of bismuth oxide, antimony oxide, zinc oxide, silicon oxide, etc., is added ethyl cellulose, butyl carbitol, n-butyl acetate, etc. as an organic binder. To
Apply to the side of the calcined body to a thickness of 30 to 300 μm.

Next, this is fired at a temperature raising / lowering rate of 30 to 60 ° C./hr, 1000 to 1300 ° C., preferably 1100 to 1250 ° C. for 2 to 7 hours to obtain an element for a voltage non-linear resistor.

In addition, a glass paste obtained by adding ethyl cellulose, butyl carbitol, n-butyl acetate or the like to a glass powder as an organic binder is applied on the insulating coating layer to a thickness of 100 to 300 μm, and the temperature rising / falling rate is 100 to 200 in air. ° C / hr, 400-600
It is preferable to form the glass layer by heat-treating at a temperature of 0.5 to 2 hours.

Then, the two end surfaces of the obtained voltage non-linear resistor element body are passed, for example, between two parallel diamond whetstones that are separated by a predetermined distance,
Grind. In order to prevent the mechanical parts that drive the grindstone from being corroded during this polishing, water containing a rust preventive agent containing organic amine, glycerin, and an inorganic salt as a main component, and adjusting the pH to within 6 to 10 grindstone It is carried out while being supplied to. But,
If the mechanical part that drives the grindstone to rotate is made of a material that does not corrode, the anticorrosive agent can of course be omitted. With such a polishing method, it takes about 60 minutes to polish a conventional lapping machine while applying a grinding liquid, whereas the polishing can be performed in a short time of about 0.5 to 10 minutes. In this case, the polishing machine may be of any other type as long as it can polish to a specified size within 10 minutes. After polishing and washing, the polished element body is naturally dried. It is preferable to heat and dry at a temperature of 50 to 200 ° C. for 10 minutes to 2 hours.

Finally, electrodes are formed by spraying, coating, or vapor-depositing an electrode material such as aluminum, gold, silver, or copper on the required electrode formation regions on both end surfaces of the polished element. The electrode material is not particularly limited as long as it is a conductive substance other than the above.

(Example) Example 1 In a voltage nonlinear resistor having a diameter of 47 mm and a thickness of 22.5 mm produced by the above-described procedure, water containing a rust preventive agent was applied to two parallel diamond whetstones according to the present invention. While preparing samples 1 to 5 which were polished while changing the time variously, and samples 6 and 7 which were polished while changing the time variously while sprinkling water containing an abrasive on a conventional lapping machine. , Voltage non-linearity index and lightning surge discharge withstand rate pass rate were investigated.

Here, the voltage non-linearity index α is based on I = kV ^α (I: current, V: voltage, k: constant) based on the voltage V _1mA across the resistor when 1 mA is supplied and the resistor when 100 μA is supplied. Both end voltage V ₁₀₀ μ _A
The ratio between, i.e., obtained from _{α = 1 / log (V 1mA} / V 100 μ A).

The lightning surge discharge withstand rate is indicated by the pass rate (%) after the current having a waveform of 4/10 μs is repeatedly applied twice.

The results are shown in Table-1.

As is clear from Table 1, all of Sample Nos. 1 to 5, which are voltage nonlinear resistors manufactured according to the present invention, have good voltage nonlinear index and good lightning surge discharge withstand capability. Was confirmed.

(Effects of the Invention) Thus, according to the present invention, the influence of water on the element for the voltage non-linear resistor is reduced, and as a result, stable electric characteristics,
In particular, a voltage non-linear resistor having a good voltage non-linear index can be obtained.

Claims (1)

[Claims] 1. Polishing the surface of an electrode forming region of an element body before forming electrodes on the element body for a voltage non-linear resistor containing zinc oxide as a main component. A method for producing a voltage non-linear resistor, characterized in that the contact time of the body surface with the grinding water is within 10 minutes.