KR20200074880A - ZnO-BASED VARISTOR COMPOSITION AND METHOD OF MANUFACTURING THE SAME AND VARISTOR USING THE SAME - Google Patents

Abstract

According to the present invention, disclosed is a ZnO-based varistor composition from which the addition of Bi_2O_3, V_2O_5, Pr_6O_11 and Pr_2O_3 is deliberately excluded. According to the present invention, the ZnO-based varistor composition includes: 85.5-99 mol% of ZnO; 0.1-2 mol% of Te_2MoO_7; and 0.1-2 mol% of at least one of an Mn oxide and a Co oxide. As a result, the ZnO-based varistor composition has a high nonlinear coefficient and a low leakage current and has excellent work stability when manufactured. Most of all, since the composition can be plasticized simultaneously with a metal electrode due to the feasibility of sintering at a low temperature, which is more or less than approximately 900°C, a multilayered varistor element can be manufactured by using a disc type or bulk type varistor or an internal electrode of a low-temperature melting metal material such as 100% Ag or the like, which can lead to a reduction in manufacturing costs.

Description

ZnO-based varistor composition and method for manufacturing the same, and varistor thereof {ZnO-BASED VARISTOR COMPOSITION AND METHOD OF MANUFACTURING THE SAME AND VARISTOR USING THE SAME}

The present invention relates to a ZnO-based varistor composition and a method for manufacturing the same, and to a varistor thereof, more specifically, Bi ₂ O ₃ , V ₂ O that deteriorates electrical properties of the varistor and requires high temperature sintering temperature by component control. ZnO-based varistor composition designed to enable simultaneous firing with metal electrodes at a low temperature while enabling high nonlinearity and low leakage current while completely excluding the addition of ₅ , Pr ₆ O ₁₁ and Pr ₂ O ₃ and preparation thereof It is about the method and the varistor.

Varistors protect electronic circuits and components used in electronic devices such as portable terminals from abnormal voltages such as surges and pulsed noises, especially electronic circuits against the occurrence of electrostatic discharge (ESD). And it ensures the protection of components and operational stability and effectively responds to noise.

In general, a varistor has a very simple structure consisting of only a solid composition and an electrode attached to the surface, so that the performance of the device is entirely dependent on the properties of the composition. Therefore, the development of a composition having excellent properties for varistors is key.

Currently developed varistor compositions include ZnO-based, SnO _2- based, SiC-based and SrTiO _3- based compositions. Among these, the ZnO-based varistor composition has excellent voltage nonlinearity and is suitable for anti-static and surge protection. Such ZnO-based varistor compositions are mainly developed as Bi-ZnO-based compositions, Pr-ZnO-based compositions, and the like.

First, the Bi-ZnO-based varistor composition is a basic composition, and Bi is added to ZnO. In general, components such as Sb, Mn, Co, Ni, Cr, glass frit, Mg, Al, K, and Si can be further contained. Yes (Japanese Patent Publication No. Hei 3-278402, Japanese Patent Publication No. 2006-310712).

By the way, the Bi ₂ O ₃ component is sintered in liquid phase while having four or more kinds of homogeneity during sintering of the varistor composition containing it, thereby forming phases with high ionic conductivity inside the varistor, and when these phases generate static electricity (ESD), Easily causes an internal short with respect to the applied external voltage, and easily collapses the partition walls in the microstructure inside the composition, thereby easily causing an insulation breakdown. Therefore, the Bi-ZnO-based varistor composition containing the Bi ₂ O ₃ component has a serious problem that ESD resistance is poor.

In addition, there is an attempt to enable low-temperature liquid sintering at around 900°C by adding V ₂ O ₅ to the Bi-ZnO-based composition to improve poor sintering properties, but due to internal abnormalities generated thereby, leakage current is increased and nonlinearity is increased. This lowers, causing problems in practical application.

On the other hand, the Pr-ZnO-based varistor composition has advantages such as a good voltage nonlinearity and a high ESD resistance. The Pr-ZnO-based varistor composition is a basic composition, and a Pr element is added to ZnO. In general, Zn, Co, Mg. It may further contain components such as K and Si (Japanese Laid-Open Patent Publication No. Hei 5-283209, Japanese Laid-Open Patent Publication No. 2006-310712).

However, the Pr-ZnO-based varistor composition has the disadvantage that the leakage current is large and the surge tolerance is rather low compared to the Bi-ZnO-based varistor composition instead.

Particularly, a major drawback is that this composition contains a precious metal-based Pr ₆ O ₁₁ -based or Pr ₂ O ₃ -based component, which requires high-temperature sintering (around 1,200°C). Due to such high-temperature sintering, it is difficult to simultaneously sinter with a metal electrode such as Ag attached to the surface of the composition for the production of varistors. Therefore, in the case of manufacturing a stacked chip varistor with this composition, expensive Pd or Pt with high melting temperature as an internal electrode There is a problem in that the manufacturing cost is high because a large amount of metal such as it has to be used.

The object of the present invention is to exclude the addition of Bi ₂ O ₃ , V ₂ O ₅ , Pr ₆ O ₁₁ and Pr ₂ O ₃ , which negatively affect the varistor properties as described above and require high-temperature sintering temperature, high nonlinearity ZnO-based varistor composition and its manufacturing method, which have a coefficient and low leakage current, have excellent work stability in manufacturing, and are capable of sintering at a low temperature, thereby enabling simultaneous firing with a metal electrode, thereby reducing manufacturing cost. It is to provide that varistor.

The ZnO-based varistor composition according to an embodiment of the present invention for achieving the above object is a ZnO-based varistor composition in which Bi ₂ O ₃ , V ₂ O ₅ , Pr ₆ O ₁₁ and Pr ₂ O ₃ are intentionally not added, ZnO : 85.5 to 99 mol%; Te ₂ MoO ₇ : 0.1-2 mol%; And at least one of Mn oxide and Co oxide: 0.1 to 2 mol%.

Here, the ZnO is more preferably added at 97 ~ 98.5mol%.

The Mn oxide includes at least one selected from MnO, MnO ₂ , Mn ₂ O ₃ and Mn ₃ O ₄ .

The Co oxide includes at least one selected from CoO, Co ₂ O ₃ and Co ₃ O ₄ .

Further, the ZnO-based varistor composition further includes at least one selected from Ca oxide, Ni oxide, Sb oxide, Cr oxide, and Si oxide.

More specifically, the ZnO-based varistor composition is CaCO ₃ : 0.2 to 3 mol%; NiO: 0.2 to 1.0 mol%; Sb ₂ O ₃ : 0.1-2 mol%; Cr ₂ O ₃ : 0.1 to 0.5 mol%; And SiO ₂ : 0.2 to 2mo;%.

A method of manufacturing a varistor according to an embodiment of the present invention for achieving the above object is a step of molding a ZnO-based varistor composition into a disk or bulk; Attaching a metal electrode to opposite sides of the disk or bulk; And calcining the disk or bulk to which the metal electrode is attached to prepare a varistor, wherein the ZnO-based varistor composition comprises Bi ₂ O ₃ , V ₂ O ₅ , Pr ₆ O ₁₁ and Pr ₂ O ₃ Unintentionally added, ZnO: 85.5-99 mol%; Te ₂ MoO ₇ : 0.1-2 mol%; And at least one of Mn oxide and Co oxide: 0.1 to 2 mol%.

At this time, the firing is preferably carried out for 0.5 to 5 hours at 900 ~ 1,100 ℃ conditions.

A method of manufacturing a varistor according to another embodiment of the present invention for achieving the above object includes forming a ZnO-based varistor composition into a plurality of thick film sheets; Forming a single bulk by attaching a metal electrode to each surface of the plurality of thick film sheets, and then stacking a plurality of thick film sheets to which the metal electrodes are attached; And calcining the bulk to prepare a stacked varistor; the ZnO-based varistor composition includes Bi ₂ O ₃ , V ₂ O ₅ , Pr ₆ O ₁₁ and Pr ₂ O ₃ intentionally not added, and ZnO. : 85.5 to 99 mol%; Te ₂ MoO ₇ : 0.1-2 mol%; And at least one of Mn oxide and Co oxide: 0.1 to 2 mol%.

At this time, the firing is performed for 0.5 to 5 hours at 900 to 1,100°C.

It is preferable to use Ag material for the metal electrode.

A varistor according to an embodiment of the present invention for achieving the above object is a sintered compact of a disk type or a bulk type made of a ZnO-based varistor composition; And metal electrodes formed on opposite sides of the sintered body to perform input/output functions of electrical signals. The ZnO-based varistor composition includes Bi ₂ O ₃ , V ₂ O ₅ , Pr ₆ O ₁₁ and Pr ₂ O _3. Is not added intentionally, ZnO: 85.5 ~ 99mol%; Te ₂ MoO ₇ : 0.1-2 mol%; And at least one of Mn oxide and Co oxide: 0.1 to 2 mol%.

A varistor according to another embodiment of the present invention for achieving the above object is laminated in a plurality to form one bulk, a sintered body made of a ZnO-based varistor composition; A plurality of metal electrodes attached to both surfaces of each of the sintered bodies and sequentially buried so as to be spaced apart from each other in the interior of the bulk; And external electrode terminals attached to both sides of the bulk and electrically connected to the plurality of metal electrodes to perform input/output functions of electrical signals. The ZnO-based varistor composition includes Bi ₂ O ₃ , V ₂ O. ₅ , Pr ₆ O ₁₁ and Pr ₂ O ₃ are intentionally not added, and ZnO: 85.5 to 99 mol%; Te ₂ MoO ₇ : 0.1-2 mol%; And at least one of Mn oxide and Co oxide: 0.1 to 2 mol%.

ZnO-based varistor composition according to the present invention and a method for manufacturing the varistor, the conventional Bi ₂ O ₃ , V ₂ O ₅ , Pr ₆ O ₁₁ and Pr ₂ O ₃ components are intentionally completely excluded, while having a high nonlinear coefficient It is possible to secure work stability during manufacturing while having a low leakage current.

In addition, the ZnO-based varistor composition according to the present invention and its manufacturing method, and the varistors can be sintered at a low temperature of about 900° C., so that they can be sintered at a low temperature around 900° C. Since the varistor element can be manufactured, it has the effect of significantly lowering the manufacturing cost.

1 is a cross-sectional view showing a disk-type varistor according to an embodiment of the present invention.
Figure 2 is a side view showing a disk-type vister according to an embodiment of the present invention.
Figure 3 is a perspective view showing a bulk-type varistor according to an embodiment of the present invention.
Figure 4 is an inner cross-sectional view showing a stacked varistor according to an embodiment of the present invention.
5 is a graph showing the current (I)-voltage (V) measurement results of the varistors prepared according to Examples 1 to 5.

Advantages and features of the present invention, and methods for achieving them will be clarified with reference to embodiments described below in detail together with the accompanying drawings. However, the present invention is not limited to the embodiments disclosed below, but will be implemented in various different forms, and only the present embodiments allow the disclosure of the present invention to be complete, and common knowledge in the technical field to which the present invention pertains. It is provided to fully inform the holder of the scope of the invention, and the invention is only defined by the scope of the claims. The same reference numerals refer to the same components throughout the specification.

Hereinafter, a ZnO-based varistor composition and a method for manufacturing the same and a varistor according to a preferred embodiment of the present invention will be described in detail with reference to the accompanying drawings.

ZnO-based varistor composition

The ZnO-based varistor composition according to an embodiment of the present invention causes Bi ₂ O ₃ causing deterioration of electrostatic (ESD) characteristics, V ₂ O ₅ deteriorating leakage current characteristics and voltage nonlinearity characteristics, and an increase in sintering temperature. Pr ₆ O ₁₁ and Pr ₂ O ₃ are completely excluded intentionally, and these components can be replaced with other components to enable low-temperature sintering. Simultaneous sintering with a metal electrode is possible while exerting excellent electrical properties of varistors. have.

To this end, in the ZnO-based varistor composition according to an embodiment of the present invention, ZnO is added as a main component, Te ₂ MoO ₇ is added as an essential component, and at least one or more of Mn oxide and Co oxide is further added.

In particular, in the ZnO-based varistor composition according to the embodiment of the present invention, Te ₂ MoO ₇ performs a function as a so-called liquid sintering aid to enable low-temperature sintering. In particular, Te ₂ MoO ₇ does not internally generate abnormal signs such as deterioration of electrical (ESD) characteristics of the varistor, deterioration of leakage current characteristics and voltage nonlinearity characteristics, or an increase in sintering temperature. It was confirmed through experiments that the electrical properties of the varistor did not deteriorate even at low temperature sintering.

Therefore, in the ZnO-based varistor composition according to the embodiment of the present invention, Te ₂ MoO ₇ is added as an essential component, thereby improving electrical properties of the varistor while having good sintering even at low temperatures around 900°C.

In addition, in the present invention, as the Mn oxide, any known oxide including MnO, MnO ₂ , Mn ₂ O ₃ , Mn ₃ O ₄ , and the like can be used, and particularly, Mn ₃ O ₄ is most preferably used.

In the present invention, the Co oxide improves the overall physical properties of the varistor, and any known oxides including CoO, Co ₂ O ₃ and Co ₃ O _4, etc. can be used, especially Co ₃ O ₄ is most preferred. Do.

In addition, the ZnO-based varistor composition according to an embodiment of the present invention may further include one or more selected from Ca oxide, Ni oxide, Sb oxide, Cr oxide, and Si oxide as auxiliary components.

Here, Ca oxide improves the sinterability, increases the average particle diameter of the composition and lowers the dielectric constant.

Ni oxide has an effect of lowering the varistor voltage, and NiO may be used as an example.

In addition, the Sb oxide improves the overall physical properties of the varistor, and at the same time, effectively suppresses the grain growth of ZnO, thereby obtaining a uniform microstructure. Accordingly, the Sb oxide functions to stably control the varistor voltage, and as an example, Sb ₂ O ₃ may be used.

In addition, Cr oxide improves the overall physical properties of the varistor, and Cr ₂ O ₃ may be used as an example.

In addition, Si oxide improves nonlinearity.

As described above, the ZnO-based varistor composition according to the embodiment of the present invention is approximately 900 to 1,300°C without intentionally adding Bi ₂ O ₃ , V ₂ O ₅ , Pr ₆ O ₁₁ and Pr ₂ O ₃ components, Preferably, low-temperature sintering of approximately 900 to 1,100°C, and more preferably 900 to 950°C may be possible, but it may be possible to secure excellent varistor properties.

To this end, the ZnO-based varistor composition according to an embodiment of the present invention includes ZnO: 85.5 to 99 mol%, Te ₂ MoO ₇ : 0.1 to 2 mol%, and at least one or more of Mn oxide and Co oxide: 0.1 to 2 mol% It is desirable to do.

Here, ZnO is more preferably added at 97 to 98.5 mol%.

In the present invention, when the addition amount of Te ₂ MoO ₇ exceeds the upper limit of 2 mol%, densification and grain growth of ZnO particles are suppressed to lower the sinterability, thereby lowering the sintering density and lowering the electrical properties of the varistor.

In addition, in the present invention, when the Mn oxide and Co oxide are added alone, each addition amount is more preferably added in a composition ratio of 0.1 to 2 mol%.

When the Mn oxide is excessively added in excess of the upper limit of 2 mol%, the densification and grain growth of ZnO are suppressed to slow the sintering of the composition, thereby lowering the sintering density and forming a high varistor voltage. . Therefore, it is preferable to control the Mn oxide at a content ratio below the upper limit.

In addition, when the amount of Co oxide added exceeds 2 mol%, which is the upper limit, the densification and grain growth of ZnO particles are suppressed to lower the sinterability, and accordingly, the sintering density is lowered, thereby lowering the electrical properties of the varistor.

In addition, ZnO, Te ₂ MoO ₇ , Mn oxide and Co oxide are preferably mixed in a powder form. At this time, each of the ZnO, Te ₂ MoO ₇ , Mn oxide and Co oxide powders preferably has an average particle diameter of 50 to 900 nm, more preferably 200 to 600 nm, and most preferably 450 to 450 nm. It is good to have an average particle diameter of 550 nm.

If the average particle diameter of each of the ZnO, Te ₂ MoO ₇ , Mn oxide, and Co oxide powders is less than 50 nm, it is difficult to control the particle size during sintering, and the electrical properties of the varistor may be deteriorated. Conversely, when the average particle diameter of each of ZnO, Te ₂ MoO ₇ , Mn oxide and Co oxide powders exceeds 900 nm, densification and grain growth of ZnO particles are suppressed to decrease sinterability, and accordingly, the sintering density is lowered to decrease the sintering density. There is a risk of deteriorating electrical properties.

In addition, ZnO-based varistor composition according to an embodiment of the present invention CaCO ₃ : 0.2 ~ 3mol%, NiO: 0.2 ~ 1.0mol%, Sb ₂ O ₃ : 0.1 ~ 2mol%, Cr ₂ O ₃ : 0.1 ~ 0.5mol% , And SiO ₂ : 0.2 to 2mo;%.

When the amount of CaCO ₃ added exceeds 3 mol%, which is the upper limit, the initial densification and grain growth of ZnO are suppressed and physical properties are difficult to control.

In addition, when the amount of NiO added exceeds the upper limit of 1.0 mol%, the leakage current increases rapidly and nonlinearity decreases.

In addition, when each addition amount of Sb ₂ O ₃ and SiO ₂ exceeds the upper limit of 2 mol%, the sinterability decreases, the sintering density decreases, the sintering temperature increases, and the voltage of the varistor increases significantly.

In addition, when the amount of Cr ₂ O ₃ added exceeds the upper limit of 0.5 mol%, the leakage current increases and the nonlinearity decreases.

Varistor and its manufacturing method

The varistor production method using the ZnO-based varistor composition according to the embodiment of the present invention can be produced by any known production method including an oxide mixing method. In addition, all the molding methods known in this field, such as dry molding, cold isostatic pressing (CIP) or warm isostatic pressing (HIP), extrusion molding, tape casting, etc., are generally applied to the application raw material powder prepared in this way. It can be molded and sintered into a form.

Hereinafter, a method of manufacturing a varistor according to an embodiment of the present invention will be described with reference to the accompanying drawings.

1 is a cross-sectional view showing a disk-type varistor according to an embodiment of the present invention, FIG. 2 is a side view showing a disk-type vister according to an embodiment of the present invention, and FIG. 3 is a bulk-type varistor according to an embodiment of the present invention. It is a perspective view.

1 to 3, the varistor according to an embodiment of the present invention may be manufactured in a disc shape or a bulk shape.

That is, after mixing and drying the ZnO-based varistor composition having the above-described composition and composition ratio in a solvent, the pulverized starting material powder is a single disk ("12" in FIGS. 1 and 2) or bulk ("22" in FIG. 3). ), and then apply metal electrode materials on both surfaces of the disk 12 or bulk 22 to form metal electrodes (13 in FIGS. 1 and 2 or 23 in FIG. 3), and then the metal electrode By simultaneously firing the coated disk or bulk with a metal electrode, a general disk type 10 or bulk type 20 varistor can be manufactured.

At this time, as the electrode material, a known electrode material such as Ag, Pd, Ag/Pd alloy may be used, but as described above, the ZnO-based varistor composition can be sintered at a low temperature, so it is most preferable to use an Ag material in consideration of manufacturing cost. In the disk-type varistor 10, which cannot be mounted on the surface, lead wires 14 may be attached to the metal electrodes 13 for input/output of electric signals.

The disk-shaped or bulk-type varistor manufactured by the above process includes a disk-shaped or bulk-shaped sintered body made of a ZnO-based varistor composition, and metal electrodes formed on opposite sides of the sintered body to function input/output of electrical signals.

Here, in the ZnO-based varistor composition, Bi ₂ O ₃ , V ₂ O ₅ , Pr ₆ O ₁₁ and Pr ₂ O ₃ are intentionally not added, and ZnO: 85.5 to 99 mol%, Te ₂ MoO ₇ : 0.1 to 2 mol% , And at least one of Mn oxide and Co oxide: 0.1 to 2 mol%.

On the other hand, Figure 4 is an internal cross-sectional view showing a stacked varistor according to an embodiment of the present invention.

4, the ZnO-based varistor composition having the above-described composition and composition ratio was mixed in a solvent and dried, then molded into a plurality of sheets using a pulverized starting raw material powder, and then laminated by stacking these sheets in a plurality. The internal electrodes 33 are formed on the surfaces of the sheets 32 to be stacked therein, except for dummy sheets (that is, sheets on which no electrodes are applied) to be formed on the top and bottom layers, respectively. By applying the electrode material to form, and then stacking the sheets and dummy sheets therein sequentially, it is possible to manufacture the laminated varistor 30.

Similarly, as the electrode material, a known electrode material such as Ag, Pd, Ag/Pd alloy can be used, but as described above, the ZnO-based varistor composition can be sintered at a low temperature, so it is most preferable to use an Ag material in consideration of manufacturing cost. In addition, external electrode terminals 35 may be formed at both ends of the varistor 30 for electrical signal input and output, and may be electrically connected to the internal electrodes 33, respectively.

The stacked varistors manufactured by the above process are stacked in a plurality to form one bulk, and are attached to both sides of the sintered body made of a ZnO-based varistor composition, and each of the sintered bodies, and sequentially spaced apart from each other in the interior of the bulk. It includes a plurality of buried metal electrodes, and external electrode terminals attached to both sides of the bulk and electrically connected to the plurality of metal electrodes to perform input/output functions of electrical signals.

Here, in the ZnO-based varistor composition, Bi ₂ O ₃ , V ₂ O ₅ , Pr ₆ O ₁₁ and Pr ₂ O ₃ are intentionally not added, and ZnO: 85.5 to 99 mol%, Te ₂ MoO ₇ : 0.1 to 2 mol% , And at least one of Mn oxide and Co oxide: 0.1 to 2 mol%.

As described so far, the ZnO-based varistor composition according to the embodiment of the present invention and its manufacturing method, and the conventional var ₂ O ₃ , V ₂ O ₅ , Pr ₆ O ₁₁ and Pr ₂ O ₃ components are intentional As it is completely excluded, it is possible to secure a work stability during manufacturing while having a high nonlinearity coefficient and a low leakage current.

In addition, the ZnO-based varistor composition according to an embodiment of the present invention and its manufacturing method, and the varistor can be sintered at a low temperature of about 900° C., thereby providing a disk-type or bulk-type varistor, or a metal material internal electrode of 100% low temperature melting. It can be used to manufacture a stacked varistor element, which has the effect of significantly lowering the manufacturing cost.

Example

Hereinafter, the configuration and operation of the present invention through a preferred embodiment of the present invention will be described in more detail. However, this is provided as a preferred example of the present invention and cannot be interpreted as limiting the present invention in any sense.

The contents not described here will be sufficiently technically inferred by those skilled in the art, and thus the description thereof will be omitted.

1. Varistor Specimen Preparation

After weighing with the ingredients and component ratios listed in Table 1, ethanol of twice the total weight of the weighing agent and 0.1 wt% of a dispersant of the total weight of the weighing material were put together into a ball mill containing 5 mmΦ partially stabilized zirconia (YSZ). Mix and crush.

Next, dehydration and drying were performed to prepare granulated powder to prepare a starting raw material powder having an average particle size of 450 nm.

Next, a predetermined amount of starting raw material powder was put into a 10 mm Φ molding mold and uniaxially press-molded at a pressure of 50 MPa to produce a disk type, and Examples 1 to 4 were at 900°C and Example 5 was at 1,000°C. Each was sintered in air for 1 hour.

Next, after polishing both surfaces of the sintered body thus obtained to have a thickness of about 1 mm, an Ag paste for ohmic contact is applied to both ends of the sintered body, followed by baking at 550° C. for 10 minutes to form external electrodes and measuring properties. A disk-shaped varistor specimen of a dragon was prepared.

[Table 1]

2. Property evaluation

Table 2 shows the evaluation results of the properties of the varistors prepared according to Examples 1 to 5, and FIG. 5 is a graph showing the results of measuring the current (I)-voltage (V) of the varistors prepared according to Examples 1 to 5 .

At this time, for each of the varistor specimens prepared according to Examples 1 to 5, a log stair pulse waveform at room temperature using DC current voltage supply and a meter (Keithley 237) for each current-voltage (IV) characteristic It was measured by applying.

The varistor voltage (Vn), which is a current-voltage characteristic parameter, is a voltage when a current of 1 mA/cm 2 flows and is measured in [V/mm], and the leakage current (IL) is the current [㎂/cm 2] measured at 80% of Vn. ], and the nonlinear coefficient (α) was calculated using the following equation (1).

(At this time, E1 and E2 are electric fields at J1(=1㎃/㎠) and J2(=10㎃/㎠), respectively.)

[Table 2]

As shown in Table 2 and FIG. 5, it was observed that the varistor specimens prepared according to Examples 1 to 5 were generally high in density, excellent in nonlinearity, and low in leakage current.

In particular, in the case of the varistor specimens prepared according to Examples 1 to 4, despite sintering at a low temperature of 900° C., it was confirmed that they exhibit excellent overall electrical properties.

Based on the results of the above experiments, the varistor specimens prepared according to Examples 1 to 5 were added to one or more of Mn oxide and Co oxide in addition to ZnO and Te ₂ MoO ₇ as the existing composition, so that conventional Bi ₂ O ₃ , V Even without the intentional addition of ₂ O ₅ , Pr ₆ O ₁₁ and Pr ₂ O ₃ components, it still has a high nonlinearity coefficient and a low leakage current, and can be sintered at low temperatures around 900°C, resulting in simultaneous firing with metal electrodes. Since it is possible to manufacture a stacked chip varistor device using a disk-type or bulk-type varistor, or a 100% Ag internal electrode, it was proved that the manufacturing cost can be lowered and the working stability is excellent.

In the above, the embodiments of the present invention have been mainly described, but various changes or modifications can be made at the level of a person skilled in the art to which the present invention pertains. These changes and modifications can be said to belong to the present invention without departing from the scope of the technical idea provided by the present invention. Therefore, the scope of the present invention should be judged by the claims set forth below.

10: disc type varistor 12: ceramic disc
13: metal electrode 14: lead wire
20: bulk type varistor 22: ceramic bulk
23: metal electrode 30: stacked varistor
32: ceramic laminate 33: internal metal electrode
35: external metal electrode terminal

Claims (13)

A ZnO-based varistor composition in which Bi ₂ O ₃ , V ₂ O ₅ , Pr ₆ O ₁₁ and Pr ₂ O ₃ are intentionally not added,
ZnO: 85.5 to 99 mol%;
Te ₂ MoO ₇ : 0.1-2 mol%; And
At least one of Mn oxide and Co oxide: 0.1 to 2 mol%;
ZnO-based varistor composition comprising a.
According to claim 1,
The ZnO is
ZnO-based varistor composition, characterized in that added at 97 ~ 98.5mol%.
According to claim 1,
The Mn oxide
A ZnO-based varistor composition comprising at least one selected from MnO, MnO ₂ , Mn ₂ O ₃ and Mn ₃ O ₄ .
According to claim 1,
The Co oxide
ZnO-based varistor composition comprising at least one selected from CoO, Co ₂ O ₃ and Co ₃ O ₄ .
According to claim 1,
The ZnO-based varistor composition
ZnO-based varistor composition, characterized in that it further comprises at least one selected from Ca oxide, Ni oxide, Sb oxide, Cr oxide and Si oxide.
According to claim 1,
The ZnO-based varistor composition
CaCO ₃ : 0.2-3 mol%;
NiO: 0.2 to 1.0 mol%;
Sb ₂ O ₃ : 0.1-2 mol%;
Cr ₂ O ₃ : 0.1 to 0.5 mol%; And
SiO ₂ : ZnO-based varistor composition further comprising at least one selected from 0.2 to 2mo;%.
Forming a ZnO-based varistor composition into disks or bulks;
Attaching a metal electrode to opposite sides of the disk or bulk; And
It includes; firing the disk or bulk to which the metal electrode is attached to manufacture a varistor; includes,
In the ZnO-based varistor composition, Bi ₂ O ₃ , V ₂ O ₅ , Pr ₆ O ₁₁ and Pr ₂ O ₃ are intentionally not added, and ZnO: 85.5 to 99 mol%; Te ₂ MoO ₇ : 0.1-2 mol%; And Mn oxide and at least one or more of Co oxide: 0.1 ~ 2mol%; Varistor manufacturing method comprising a.
The method of claim 7,
The firing
Varistor manufacturing method characterized in that for 0.5 to 5 hours at 900 ~ 1,100 ℃ conditions.
Forming a ZnO-based varistor composition into a plurality of thick film sheets;
Forming a single bulk by attaching a metal electrode to each surface of the plurality of thick film sheets, and then stacking a plurality of thick film sheets to which the metal electrodes are attached; And
It comprises; firing the bulk to produce a laminated varistor;
In the ZnO-based varistor composition, Bi ₂ O ₃ , V ₂ O ₅ , Pr ₆ O ₁₁ and Pr ₂ O ₃ are intentionally not added, and ZnO: 85.5 to 99 mol%; Te ₂ MoO ₇ : 0.1-2 mol%; And Mn oxide and at least one or more of Co oxide: 0.1 ~ 2mol%; Varistor manufacturing method comprising a.
The method of claim 9,
The firing
Varistor manufacturing method characterized in that for 0.5 to 5 hours at 900 ~ 1,100 ℃ conditions.
The method of claim 7 or 9,
The metal electrode
Varistor manufacturing method characterized in that using an Ag material.
Disk-shaped or bulk-shaped sintered body made of ZnO-based varistor composition; And
It is formed on the opposite sides of the sintered body to function as an electrical signal input and output; includes,
In the ZnO-based varistor composition, Bi ₂ O ₃ , V ₂ O ₅ , Pr ₆ O ₁₁ and Pr ₂ O ₃ are intentionally not added, and ZnO: 85.5 to 99 mol%; Te ₂ MoO ₇ : 0.1-2 mol%; And at least one of Mn oxide and Co oxide: 0.1 to 2 mol%.
A sintered body composed of a plurality of ZnO-based varistor compositions stacked in plural to form one bulk;
A plurality of metal electrodes attached to both surfaces of each of the sintered bodies and sequentially buried so as to be spaced apart from each other in the interior of the bulk; And
It includes; external electrode terminals attached to both sides of the bulk and electrically connected to each of the plurality of metal electrodes to perform input/output of an electrical signal;
In the ZnO-based varistor composition, Bi ₂ O ₃ , V ₂ O ₅ , Pr ₆ O ₁₁ and Pr ₂ O ₃ are intentionally not added, and ZnO: 85.5 to 99 mol%; Te ₂ MoO ₇ : 0.1-2 mol%; And at least one of Mn oxide and Co oxide: 0.1 to 2 mol%.

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