JPH08153565A - Surge absorber - Google Patents

Abstract

PURPOSE: To prevent overheat or firing of an electronic apparatus etc., by stopping electric discharge quickly when an over-current or over-voltage is impressed. CONSTITUTION: A surge absorber 15 is structured so that a surge absorptive element 20 is accommodated in a tube 11 holding insulativeness together with an inert gas 14 consisting of CO2 gas or a mixture of CO2 gas and He, Ne, Ar, etc. The element 20 is formed with a gap 23 to split a film on the peripheral surface of a columnar ceramic material 22 enclosed with an electroconductive ceramic thin film 21, and a pair of cap electrodes 24, 25 are provided at the ends of the ceramic material 23. A pair of sealed electrodes 12, 13 are opposingly attached sealedly at the two ends of the tube 11, and the element 20 is fixed by the sealed electrodes in sealed condition, which are connected electrically with the cap electrodes.

Description

Detailed Description of the Invention

[0001]

The present invention relates to a telephone, a facsimile,
In addition to the function of absorbing surge voltage applied to electronic devices for communication equipment such as telephone exchanges and modems, the electronic device and the printed circuit board on which this device is mounted during continuous overvoltage or overcurrent intrusion into the electronic device. The present invention relates to a surge absorber that prevents thermal damage or ignition. More specifically, the present invention relates to a discharge type surge absorber in which a surge absorbing element having a gap is hermetically sealed with a tube that maintains insulation with an inert gas. In the present specification, the overvoltage or overcurrent refers to an abnormal voltage exceeding the discharge start voltage of the surge absorber and an abnormal current associated therewith.

[0002]

2. Description of the Related Art Conventionally, as hermetically sealed gap type surge absorbers, surge absorbers 9a and 9b as shown in FIGS. 7 and 8 have been known. The gap type surge absorbing element 1 built in the two surge absorbers 9a and 9b has a conductive film 1a such as SnO _2.
A microgap 1c having a width of several 10 μm that divides the coating film 1a into two in the circumferential direction is formed in the center of a cylindrical ceramic body 1b encapsulated by the above. It is made by wearing. Electrical insulation is achieved between the films divided into two by the microgap 1c. As shown in FIG. 7, the surge absorber 9a
Accommodates the surge absorbing element 1 in a tube 4 that maintains insulation properties, arranges a pair of sealing electrodes 2 and 3 at both ends of the surge absorbing element 1, and connects these sealing electrodes 2 and 3 to the cap electrodes 1d, 1e
And an inert gas 5 such as Ar gas is sealed inside the tube 4 at the same time. Lead wires 6 and 7 are connected to the sealing electrodes 2 and 3, respectively.

As shown in FIG. 8, a surge absorber 9b is provided.
Is made by sealing the gap type surge absorbing element 1 with the glass tubes 8 together with the lead wires 6 and 7 connected to the cap electrodes 1d and 1e at both ends thereof. The glass tube 8 is filled with an inert gas 5 such as Ar gas. In the above surge absorber 9a or 9b, the lead wires 6, 6
When an abnormal voltage is applied to 7, glow discharge first occurs along the conductive film 1a enclosing the cylindrical ceramic body 1b, and finally an arc discharge occurs between the pair of cap electrodes 1d and 1e. And absorb the surge voltage.

The surge absorber 9a or 9b is connected to a pair of input lines of an electronic device in parallel with the electronic device and is configured to operate at a voltage higher than the operating voltage of the electronic device. That is, although the surge absorber is a resistor having a high resistance value at a voltage lower than its discharge starting voltage,
When the applied voltage is equal to or higher than the discharge start voltage, the resistance element has a low resistance value of several tens Ω or less. When a surge voltage such as a lightning surge of several kV to several tens of kV is momentarily applied to the electronic device, the surge absorber is discharged, and the surge voltage is absorbed to protect the electronic device.

However, if an overvoltage or an overcurrent (for example, 300 mA at 600 VAC) is continuously applied to a circuit including electronic equipment, a current continues to flow in the surge absorber. As a result, the surge absorber generates heat, which causes ignition of electronic devices in the vicinity. Normally, it is unlikely that such an overvoltage or overcurrent will continue to enter the circuit, but it is becoming more and more popular to take maximum safety measures in anticipation of an unexpected accident. For example, in the United States UL (Underwriter's Laboratories Inc.), surge absorbers must be installed so that they do not pose a risk of fire or electric shock to communication equipment during such continuous overvoltage or overcurrent intrusion. Established prescribed safety standards.

As another conventional surge absorber that complies with such safety standards and can prevent ignition of electronic equipment due to continuous overvoltage or overcurrent, a low melting point metal wire 10 as shown in FIG. 5 is used. There is known a surge absorber 9c which is in close contact with the surface of the tube 4 of the surge absorber 9a shown in FIG. This surge absorber 9c has a low melting point metal wire 10
The surge absorber 9a and the surge absorber 9a are sealed by the substrate 10a and the cover 10b, and the terminals 10c and 10d of the low melting point metal wire 10 are sealed.
And the terminals 10e and 10f of the lead wires 6 and 7 on the substrate 10
They are separately projected from a. The surge absorber 9c has a continuous overvoltage or overcurrent (for example, AC6).
The low melting point metal wire 10 when there is an intrusion of 300 mA at 00V.
It is possible to prevent not only abnormal heat generation of the surge absorber 9a, but also thermal damage and ignition of the electronic device and the printed circuit board on which the device is mounted.

[0007]

However, the surge absorber 9c has the above-mentioned features, but has a drawback that the low melting point metal wire 10 is easily fused when a high surge current enters, so that the surge absorber 9c has a relatively low surge resistance. . Further, the surge absorber 9c has a large number of parts, has a complicated structure, is difficult to be miniaturized, and is difficult to reduce the manufacturing cost.

The object of the present invention is not only to absorb a momentary surge voltage such as lightning surge, but also to not only abnormal heat generation of the surge absorber when a continuous overvoltage or overcurrent is introduced. It is possible to prevent thermal damage, ignition, etc. of electronic devices and printed circuit boards equipped with this device.
Moreover, it is to provide a surge absorber having a high surge resistance. Another object of the present invention is to provide a surge absorber that requires a small number of parts, is easy to manufacture, is easy to miniaturize, and is excellent in mass productivity. Still another object of the present invention is to have a good response to a surge impulse,
An object of the present invention is to provide a surge absorber capable of increasing the discharge start voltage.

[0009]

In order to achieve the above object, as shown in FIG. 1, a first surge absorber 15 of the present invention comprises a cylindrical ceramic body 22 covered with a conductive coating 21. A surge absorbing element 20 having a gap 23 that divides the coating film 21 on the peripheral surface of the ceramic element body 22 and having a pair of cap electrodes 24 and 25 at both ends of the ceramic body 22 is housed in the tube 11 that maintains the insulating property together with the inert gas 14. A pair of sealing electrodes 12 and 13 are provided on both ends of the tube 11 that maintains the insulating property.
Are opposed to each other and sealed, and the pair of sealing electrodes 12 and 13 fixes the surge absorbing element 20 in the sealed state and is electrically connected to the pair of cap electrodes 24 and 25. The characteristic structure is that the conductive film 21 is a conductive ceramic thin film and the inert gas 14 is only CO ₂ gas, or CO ₂ gas and He, Ne, Ar, Kr, Xe or N ₂ gas. It is to be a mixed gas of. In the first surge absorber, although not shown, the pair of cap electrodes 24,
25 may be omitted and the pair of sealing electrodes may be electrically connected directly to the conductive film.

As shown in FIG. 2, in the second surge absorber 35 of the present invention, a pair of lead wires 26 and 27 are connected to the cap electrodes 24 and 25 of the surge absorbing element 20. Is sealed with a tube 16 which maintains insulation together with the inert gas 14, and a pair of lead wires 26 and 27 are formed so as to project from the tube 16. The characteristic structure is that the conductive film 21 is a conductive ceramic thin film and the inert gas 14 is only CO ₂ gas, or CO ₂ gas and He, Ne, Ar, Kr, Xe.
Alternatively, it is a mixed gas of N ₂ gas.

The present invention will be described in detail below. As shown in FIGS. 1 and 2, the gap type surge absorbers 15 and 35.
The surge absorbing elements 20 are housed inside the tubes 11 and 28 that maintain insulation. In the surge absorber 20, a pair of cap electrodes 24 and 25 are capped on both ends of a cylindrical ceramic body 22 covered with a conductive film 21, and then a gap 23 is circumferentially formed in the center of the ceramic body 22. Formed and made. As described above, the cap electrodes 24 and 25 may be omitted in the surge absorber 15. The conductive film 21 is formed on the surface of the ceramic body 22 so as to cover the ceramic body 22 by a thin film forming method such as a sputtering method, a vapor deposition method, an ion plating method, a plating method and a CVD method. The conductive film 21 of the present invention is a conductive ceramic thin film. This conductive film is preferably made of any one of a conductive metal oxide, a conductive nitride and a conductive carbide. The conductive metal oxide is SnO ₂ ,
Nb ₂ O ₅ , MnO ₂ or MoO ₃ is exemplified, and particularly SnO.
₂ is preferable because the film formation is easy and the gap can be easily formed. The conductive nitride is exemplified by TiN or TaN, and the conductive carbide is exemplified by SiC.

The gap 23 is formed by laser light or a diamond blade so as to divide the conductive film 21. The larger this division, the higher the discharge start voltage, and the longer the life. When the gap 23 is one, the conductive film 21 is divided into two, and when a plurality of gaps are formed, the conductive film 21 is divided into three or more. The gap is at most 10 per line due to the depth of focus of the laser beam and the thickness of the conductive film.
It is formed with a width of 00 μm. The wider the gap width, the higher the discharge starting voltage can be. This gap width is 1
200-1000 μm is preferable per line, 500-10
00 μm is more preferable. If it exceeds 1000 μm, the response to the surge impulse becomes poor, which is not preferable. The gap 23 is formed by removing only the conductive film 21 or by removing the surface of the conductive film 21 and the ceramic body 22 under the film.

The surge absorber 15 accommodates the surge absorbing element 20 in a tube 11 which maintains an insulating property, and disposes a pair of sealing electrodes 12 and 13 at both ends of a ceramic body 22. 13 is electrically connected to the cap electrodes 24 and 25, or is directly connected to the conductive film 21 without providing the cap electrodes 24 and 25, and at the same time, the inert gas 14 is provided inside the tube 11 that maintains insulation. Made by enclosing. The surge absorbing element 20 housed in the sealing electrode 1 is sealed when the pair of sealing electrodes 12 and 13 is sealed to both ends of the tube 11.
It is fixed by 2, 13. On the other hand, surge absorber 3
After connecting the lead wires 26 and 27 to the outer surfaces of the cap electrodes 24 and 25 of the surge absorbing element 20, respectively, the lead wire 5 is housed in a tube 28 that maintains insulation, and is sealed together with the inert gas 14. The lead wires 26 and 27 are tubes 2 that maintain insulation.
Project from 8.

In the present invention, the surge absorbers 15 and 35 are
In both cases, the inert gas 14 is CO ₂ gas alone or a mixed gas of CO ₂ gas and He, Ne, Ar, Kr, Xe or N ₂ gas. The mixing ratio is at least 70% by volume of CO ₂ gas, and the balance is He, Ne, Ar, K.
It is preferably r, Xe or N ₂ gas. The mixing ratio may be at least 50% by volume of CO ₂ gas, or at least 30% by volume. CO ₂ gas is a negative filling gas that adsorbs electrons during discharge and becomes negative ions to increase the discharge start voltage, and has a feature that it does not decompose even if it is filled at 800 ° C. The filling gas pressure of this CO ₂ gas or a mixed gas of CO ₂ gas and He or the like is 300 to 1300To.
rr is preferable, and 800 to 1300 Torr is further preferable. If the filling gas pressure is less than 300 Torr, the effect of filling the CO ₂ gas is poor, and if it exceeds 1300 Torr, the durability of the filling machine is likely to have a problem. Since the discharge starting voltage is a function of the product of the gap width and the enclosed gas pressure (hereinafter referred to as the pd value) described above from Paschen's law, the enclosed gas pressure is set according to the gap width. The insulating tube of the present invention is a glass tube, a ceramic tube, or the like. The glass tube is a hard glass such as borosilicate glass,
Or made from soft glass such as lead glass, soda lime glass. The ceramic tube is not limited to one made of a ceramic sintered body that transmits visible light, such as PLZT or transparent alumina, but may be another ceramic tube having an insulating property. Further, the insulating tube according to the present invention includes a tube made of an insulating material at a portion in contact with the lead wire 26 or 27 of the surge absorber 35 shown in FIG. 2 and a tube made of a conductive material at the other portions.

[0015]

When the surge absorber 15 or 35 of the present invention is continuously connected to the line to which the surge absorber 15 or 35 is connected, the surge absorber 15 or 35 is discharged. When CO ₂ gas or a mixed gas containing CO ₂ gas is used as the filling gas, the degree of damage to the conductive film 21 due to the heat generation of this discharge becomes more serious and the gap interval is widened, as compared with the conventional Ar gas. As a result, before the surge absorber 15 or 35 can be fatally damaged by heat, its resistance value increases, the discharge start voltage and the discharge sustaining voltage become higher than the overvoltage, and the discharge is stopped. In addition, the filling gas is CO ₂ gas or C
By using the mixed gas containing O ₂ gas, the response delay to the surge impulse is small even when the gap width is in a relatively wide range of 200 to 1000 μm.
The CO ₂ gas, which is the filling gas, does not decompose even at a filling temperature of about 0 ° C.

[0016]

Embodiments of the present invention will now be described in detail with reference to the drawings together with comparative examples. <Example 1> A gap type surge absorber 1 shown in FIG.
5 was manufactured by the following method. First, the tube 11 that maintains the insulation
A surge absorbing element 20 housed inside was prepared. The cylindrical ceramic body 22 of the surge absorbing element 20 is made of a mullite sintered body, and its surface is covered with a conductive film 21 made of tin oxide (SnO ₂ ). This SnO ₂ thin film is obtained by spraying tin chloride (SnCl ₄ ) on the surface of the ceramic body 22 kept at a high temperature. Cap electrodes 24 and 25 made of stainless steel are attached to both ends of the ceramic body 22. The conductive film 21 and the ceramic element body 22 are circumferentially trimmed by irradiating the central portion of the ceramic element body 22 with a laser beam to obtain one of the width of about 30 μm and the depth of 30 μm from the surface of the ceramic element body 22. The gap 23 was formed.

A low melting point lead glass tube was prepared as the tube 11 for maintaining insulation, and the glass tube 11 was placed in a sealing chamber (not shown) provided with a carbon heater. The surge absorbing element 20 is placed inside the glass tube 11, and the sealing electrodes 12 and 13 are inserted.
Was inserted into the glass tube 11 to sandwich the surge absorbing element 20. The sealing electrode 12 was electrically connected to the cap electrode 24, and the sealing electrode 13 was electrically connected to the cap electrode 25. After the air inside the glass tube is evacuated by setting the negative pressure in the sealing chamber, carbon dioxide (CO ₂ ) gas is supplied to the sealing chamber instead and the CO ₂ gas 14 is supplied into the glass tube at a pressure of 800 Torr. Introduced. In this state, the glass tube 11 and the sealing electrodes 12 and 13 are 740 with a carbon heater.
Heated at 1 ° C for 1 minute. The sealing electrodes 12 and 13 are the glass tube 1.
Sealed to 1. This surge absorber 15 has a length of 7.0.
The outer diameter was 3.3 mm and the outer diameter was 3.3 mm.

Example 2 A surge absorber 15 was manufactured in the same manner as in Example 1 except that SiC was used instead of the conductive film 21 made of SnO _{2 in} Example 1.

<Embodiment 3> As shown in FIG.
Only the conductive film 21 was trimmed with one gap 23 of μm (the depth from the surface of the ceramic body 22 was 0 μm).
The surge absorber 15 was manufactured in the same manner as in Example 1 except that (m was set to m).

Example 4 A surge absorber 15 was manufactured in the same manner as in Example 3 except that SiC was used instead of the conductive film 21 made of SnO _{2 in} Example 3.

<Embodiment 5> As shown in FIG.
The same procedure as in Example 1 was performed except that the two gaps 23 of 23 μm were trimmed only in the conductive film 21 with a gap of 0.5 mm (the depth from the surface of the ceramic body 22 was 0 μm). The surge absorber 15 was manufactured. 3 and 4, the same reference numerals as those in FIG. 1 represent the same parts.

Example 6 A surge absorber 15 was manufactured in the same manner as in Example 5 except that SiC was used instead of the conductive film 21 made of SnO _{2 in} Example 5.

<Example 7> A surge absorber 15 was produced in the same manner as in Example 1 except that a mixed gas of 30% by volume of CO ₂ gas and 70% by volume of Ar gas was used as a filling gas.

<Example 8> A surge absorber 15 was produced in the same manner as in Example 1 except that a mixed gas of 50% by volume of CO ₂ gas and 50% by volume of Ar gas was used as a filling gas.

<Comparative Example 1> The gap type surge absorber 9a shown in FIG. The surge absorber 9a has a conductive film 21 made of SnO _{2 according} to the first embodiment.
A conductive coating film 1a made of titanium is formed by sputtering instead of, and A ₂ is used instead of CO ₂ gas in Example 1.
R gas was enclosed. A surge absorber 9a was manufactured in the same manner as in Example 1 except for the above.

<Comparative Example 2> The surge absorber 9c shown in FIG. This surge absorber 9c
A low melting point metal wire 10 that melts for the first time at (8 × 20) μsec-500 A is circulated on the outer surface of the tube 4 which maintains the insulating property of the surge absorber 9a of Comparative Example 1, and both ends thereof are connected to terminals 10c and 10d penetrating the substrate 10a. Connected Further, the lead wires 6 and 7 of the surge absorber 9a were connected to terminals 10e and 10f penetrating the substrate 10a. The surge absorber 9a and the low melting point metal wire 10 were sealed with a cover 10b. The cover 10b has a height of 1.8 cm and a width of 0.9.
It has dimensions of cm and height 1.05 cm.

Comparative Example 3 Although not shown, Comparative Example 1 except that six gaps having a width of 30 μm were trimmed at a depth of 30 μm from the surface of the ceramic body at 0.1 mm intervals.
A surge absorber was manufactured in the same manner as in.

Comparative Example 4 Although not shown, a surge absorber was prepared in the same manner as Comparative Example 1 except that 12 gaps having a width of 30 μm were trimmed at a depth of 30 μm from the surface of the ceramic body at intervals of 0.1 mm. It was made.

<Comparison Test and Evaluation> With respect to the surge absorbers of Examples 1 to 8 and Comparative Examples 1 to 4, the discharge start voltage, the response voltage to the (1.2 × 50) μsec 10 kV surge voltage, the insulation resistance, and the electrostatic capacitance, respectively. Was measured, and an overvoltage / overcurrent application test and a surge withstand test were performed. However, in the surge absorber 9c of Comparative Example 2, the terminals 10d and 10e are connected and the surge absorber 9a and the low melting point metal wire 10 are connected in series as shown in FIG. Measured or tested. The overvoltage / overcurrent application test is AC
An overvoltage / overcurrent of 600 V-300 mA was applied for 5 minutes. In the surge withstand test, a current value which can withstand a (8 × 20) μsec surge was measured. Table 1 shows the results.

[0030]

[Table 1]

In Table 1, (*) is an observation result when a discharge is forcibly generated by applying a surge. As is clear from Table 1, the surge absorbers of Comparative Example 1, Comparative Example 3, and Comparative Example 4 have the drawback of sustaining discharge in the overvoltage / overcurrent application test, and the surge absorber 9 of Comparative Example 2 has a drawback.
c had a low surge resistance of 500A. On the other hand, in the surge absorbers of Examples 1 to 8, discharge was stopped in a few seconds in the overvoltage / overcurrent application test, and the surge withstand capability was as high as 1000A. Further, regarding the response voltage, the third embodiment and the fifth embodiment are more preferable than the third and fourth embodiments.
The surge absorbers of Examples 3 and 5 were superior to the surge absorbers of Comparative Examples 3 and 4 in response to surge impulses.

[0032]

As described above, according to the present invention, in addition to absorbing a momentary surge voltage such as a lightning surge, when there is a continuous overvoltage or overcurrent intrusion, The conductive film of the conductive ceramic thin film is thermally damaged and the gap interval is widened to increase the discharge start voltage and the discharge sustaining voltage, which causes not only abnormal heat generation of the surge absorber but also electronic equipment and a printed circuit board on which the equipment is mounted. It is possible to prevent thermal damage, ignition, etc. Further, since the surge absorber of the present invention does not use the conventional low-melting-point metal wire, the number of parts can be reduced, the cost can be reduced, the occupying space is small, the assembly is easy, and the mass productivity is excellent. Further, by setting the gap width to 200 to 1000 μm, the pd value can be increased even with a small number of gaps, the discharge start voltage of the surge absorber can be easily increased, and the gap formation time can be shortened.
In particular, by using CO ₂ gas or a mixed gas containing CO ₂ gas as the filling gas, the gap width is 200 to 1000 μm.
Even in a relatively wide range of m, the response delay to the surge impulse is small, and the CO ₂ gas, which is the sealed gas, is thermally stable even at a sealed temperature of about 800 ° C.
Encapsulation up to ° C is possible, the encapsulation method is not limited, and there is an advantage that productivity is improved.

[Brief description of drawings]

FIG. 1 is a central longitudinal sectional view of a gap type surge absorber of the present invention.

FIG. 2 is a vertical sectional view of another gap type surge absorber of the present invention.

FIG. 3 is a vertical cross-sectional view of the gap type surge absorber according to the embodiment of the present invention.

FIG. 4 is a vertical sectional view of a gap type surge absorber according to another embodiment of the present invention.

FIG. 5 is a perspective view of a conventional surge absorber with a low melting point metal wire.

6 is a circuit configuration diagram of the surge absorber of FIG. 5 at the time of a comparative test.

FIG. 7 is a sectional view of a conventional gap type surge absorber corresponding to FIG. 1.

FIG. 8 is a sectional view of a conventional gap type surge absorber corresponding to FIG.

[Explanation of symbols] 15,35 Surge absorber 11,28 Insulating tube (glass tube) 12,13 Sealing electrode 14 Inert gas 16,17,26,27 Lead wire 20 Surge absorbing element 21 Conductive film 22 Ceramic body 23 Gap 24,25 Cap electrode

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Takaaki Ito 1-5-1, Otemachi, Chiyoda-ku, Tokyo Sanritsu Materials Co., Ltd. (72) Inventor Mikio Harada, 2270 Yokose, Yokoze-cho, Chichibu-gun, Saitama Sanryo Materials Co., Ltd. Ceramics Factory

Claims (15)

[Claims] 1. A gap (23) for dividing the coating film (21) is formed on the peripheral surface of a cylindrical ceramic body (22) covered with a conductive coating film (21), and the ceramic body (22) is formed. ) With or without a pair of cap electrodes (24, 25) on both ends of the surge absorbing element (20) is housed in a tube (11) that maintains insulation with the inert gas (14), ), A pair of sealing electrodes (12, 13) are sealed to face each other, and the pair of sealing electrodes
(12, 13) fixing the surge absorbing element (20) in a sealed state, and a surge absorber electrically connected to the pair of cap electrodes (24, 25) or the conductive film (21) The conductive film (21) is a conductive ceramic thin film,
A surge absorber, wherein the inert gas (14) is CO ₂ gas. 2. A gap (23) dividing the coating (21) is formed on the peripheral surface of a cylindrical ceramic body (22) covered with a conductive coating (21), and the ceramic body (22) is formed. ) With or without a pair of cap electrodes (24, 25) on both ends of the surge absorbing element (20) is housed in a tube (11) that maintains insulation with the inert gas (14), ), A pair of sealing electrodes (12, 13) are sealed to face each other, and the pair of sealing electrodes
(12, 13) fixing the surge absorbing element (20) in a sealed state, and a surge absorber electrically connected to the pair of cap electrodes (24, 25) or the conductive film (21) The conductive film (21) is a conductive ceramic thin film,
The inert gas (14) is CO ₂ gas, He, Ne, A
A surge absorber characterized by being a mixed gas of r, Kr, Xe or N ₂ gas. 3. A ceramic body (22) having a cylindrical shape and a gap (23) dividing the coating (21) is formed on the peripheral surface of the cylindrical ceramic body (22). ) Has a pair of cap electrodes (24, 25) at both ends, and the cap electrodes (2
A pipe (28) in which a surge absorbing element (20) in which a pair of lead wires (26, 27) is connected to (4, 25) maintains insulation with an inert gas (14).
In a surge absorber sealed by, and the pair of lead wires (26, 27) protruding from the tube (28), the conductive film (21) is a conductive ceramic thin film,
A surge absorber, wherein the inert gas (14) is CO ₂ gas. 4. A gap (23) dividing the coating (21) is formed on the peripheral surface of a cylindrical ceramic body (22) covered with a conductive coating (21), and the ceramic body (22) is formed. ) Has a pair of cap electrodes (24, 25) at both ends, and the cap electrodes (2
A pipe (28) in which a surge absorbing element (20) in which a pair of lead wires (26, 27) is connected to (4, 25) maintains insulation with an inert gas (14).
In a surge absorber sealed by, and the pair of lead wires (26, 27) protruding from the tube (28), the conductive film (21) is a conductive ceramic thin film,
The inert gas (14) is CO ₂ gas, He, Ne, A
A surge absorber characterized by being a mixed gas of r, Kr, Xe or N ₂ gas. 5. An inert gas containing at least 70% by volume of C
The surge absorber according to claim 2, wherein the O ₂ gas is mixed with He, Ne, Ar, Kr, Xe or N ₂ gas. 6. An inert gas containing at least 50% by volume of C
The surge absorber according to claim 2, wherein the O ₂ gas is mixed with He, Ne, Ar, Kr, Xe or N ₂ gas. 7. C containing at least 30% by volume of an inert gas.
The surge absorber according to claim 2, wherein the O ₂ gas is mixed with He, Ne, Ar, Kr, Xe or N ₂ gas. 8. The surge absorber according to claim 1, wherein the conductive ceramic thin film is made of a conductive metal oxide, a conductive nitride or a conductive carbide. 9. The conductive metal oxide is SnO ₂ , Nb.
The surge absorber according to claim 8, which is ₂ O ₅ , MnO ₂ or MoO ₃ . 10. The surge absorber according to claim 8, wherein the conductive nitride is TiN or TaN. 11. The conductive carbide is SiC.
Surge absorber described. 12. The width of the gap (23) is 200 μm to 10 μm.
The surge absorber according to any one of claims 1 to 11, which has a diameter of 00 µm. 13. The gap (23) has a width of 200 μm to 50 μm.
The surge absorber according to claim 12, which has a thickness of 0 μm. 14. The surge absorber according to claim 1, wherein one gap (23) is formed on the peripheral surface of the ceramic body (22) so as to divide the conductive film (21) into two. 15. The surge according to claim 1, wherein a plurality of gaps (23) are formed on the peripheral surface of the ceramic body (22) so as to divide the conductive film (21) into three or more. Absorber.