HK1091600B - Surge absorber and production method therefor - Google Patents

Description

Surge absorber and manufacturing method thereof

Technical Field

The present invention relates to a surge absorber for protecting various devices from surge impact and preventing accidents from happening in advance.

Background

In order to prevent an electronic device or a printed circuit board mounted in the electronic device from being damaged by heat or from being damaged by an abnormal voltage, a surge absorber is connected to a portion which is likely to receive an electric shock due to an abnormal current (surge current) or an abnormal voltage (surge voltage) such as a lightning surge or static electricity, such as a power supply line, an antenna, or a CRT driving circuit, or a connection portion between the electronic device and a communication line for a communication device such as a telephone, a facsimile, or a modem.

Heretofore, for example, a discharge type surge absorber described in japanese unexamined patent publication No. 9-171881 has been proposed, in which: an element disposed in the glass tube and having terminal electrodes at both ends; a pair of dumet wires respectively connected to terminal electrodes inserted at both ends of the glass tube, one end of which is connected to a lead wire for connection with an external circuit; and cylindrical gaskets respectively externally connected to the Dumet wires and internally connected to two ends of the glass tube to seal the two ends of the glass tube. In this case, the contact between the dumet wire and the terminal electrode is unstable, and the discharge start voltage is likely to fluctuate. In addition, since the area of the terminal electrode is large, the material cost increases, and this is disadvantageous in terms of cost.

In addition, with the miniaturization of electronic devices, surface mounting of discharge surge absorbers has also progressed. A surface-Mount (MELF) surge absorber is provided with a terminal electrode without a lead, and the terminal electrode is soldered to a substrate when mounted on the substrate. As such a surge absorber, for example, surge absorbing elements having a micro gap as shown in japanese patent laid-open nos. 2002-110311 and 2002-134247 are used, and a structural example of such a surge absorber is shown in fig. 10.

The surge absorbing element 1 is configured such that a so-called micro gap M is formed in the center of the surface of a cylindrical ceramic member (insulating member) 3 whose periphery is covered with a conductive film 2, and a pair of cap electrodes 4 are attached to both ends of the ceramic member 3. The surge absorbing element 1 is housed in a glass tube 5 together with a sealing gas, and both ends of the glass tube 5 are sealed by heating at high temperature with a pair of opposing terminal electrodes 6 to form a discharge type surge absorber.

However, in recent years, surge absorbers are required to provide stable performance and quality at low cost, and also required to have high durability and high surge capacity. Therefore, the dimensional accuracy of the surge absorbing element, the glass tube, and the terminal electrode becomes a problem. In particular, it is an important technical problem to ensure reliable contact between the surge absorbing element and the sealing electrode without generating a gap therebetween.

In recent years, surge absorbers are required to have sufficiently high surge capacity even for applications requiring high surge capacity such as communication lines and power lines. In the MELF surge absorber, the glass tube may be damaged during installation. Thus, it is considered to replace the glass tube with the ceramic tube. In a surge absorber using a glass tube, a ceramic member is put into the glass tube, and the glass tube is melted in a high temperature furnace in a state where terminal electrodes are provided at both ends of the glass tube, and is tightly fixed to the terminal electrodes, thereby sealing the glass tube. When the sealed glass tube is cooled, residual stress in the compression direction is generated due to the difference in thermal expansion coefficient between the glass tube and the ceramic member, and sufficient ohmic contact between the terminal electrode and the conductive coating of the ceramic member can be obtained.

However, when a ceramic tube is used instead of the glass tube, the difference in thermal expansion coefficient between the ceramic tube and the ceramic member is smaller than that in the above case, so that residual stress generated during cooling is small, and ohmic contact between the terminal electrode and the conductive film of the ceramic member may be insufficient.

The present invention has been made in view of the above circumstances, and an object thereof is to provide a surge absorber having stable performance and quality, excellent durability, and high surge capacity at low cost.

Disclosure of Invention

In order to solve the above problems, the present invention employs the following configuration.

The surge absorber of the present invention is characterized in that: an insulating member formed by dividing the conductive film with a discharge gap interposed therebetween; a pair of terminal electrodes in contact with the conductive film disposed to face the insulating member; and an insulating tube for sealing the insulating member with a sealing gas therein by disposing the pair of terminal electrodes at both ends; a conductive portion is provided at least between the conductive film and the terminal electrode.

For example, the surge absorber of the present invention is characterized in that it is a surge absorber provided with: a columnar insulating member formed by dividing the conductive film with a discharge gap interposed therebetween on the peripheral surface; a pair of terminal electrodes facing the conductive coating at both ends of the insulating member; and an insulating tube for sealing the insulating member with a sealing gas; and a conductive filler which is contained in the conductive portion to fill a gap between the conductive film and the terminal electrode.

In this surge absorber, a gap generated at the contact surface between the terminal electrode and the conductive film due to dimensional accuracy, a flaw, and deformation during processing is filled with a conductive filler. Thus, sufficient ohmic contact between the terminal electrode and the conductive coating film can be obtained, and the electrical characteristics such as the discharge start voltage of the surge absorber can be stabilized.

Further, a surge absorber of the present invention is characterized by being provided with: a columnar insulating member formed by dividing the conductive film with the discharge gap interposed therebetween on the peripheral surface; a pair of terminal electrodes facing the conductive coating at both ends of the insulating member; and an insulating tube for sealing the insulating member with a sealing gas; a metal member is provided between the conductive film and the terminal electrode, and a conductive filler is provided as the conductive portion to fill a gap between the metal member and the terminal electrode.

In this surge absorber, a gap generated at a contact surface between the terminal electrode and the metal member due to dimensional accuracy, a flaw, deformation during processing, or the like is filled with a conductive filler. Therefore, sufficient ohmic contact between the terminal electrode and the metal member can be obtained, and the electrical characteristics such as the discharge start voltage of the surge absorber can be stabilized.

In the surge absorber, it is preferable that an oxide film is formed on a main discharge surface which is a surface of the pair of metal members facing each other by oxidation treatment.

In this surge absorber, an abnormal current and an abnormal voltage such as an electrical surge that enters from the outside trigger discharge of a micro gap, and main discharge is performed between main discharge surfaces that are surfaces of a pair of metal members facing each other, thereby absorbing the surge. Here, by forming an oxide film on the main discharge surface, a main discharge surface excellent in chemical stability in a high temperature region can be obtained. In addition, the electrode component on the main discharge surface is prevented from scattering and adhering to the micro-gap and the inner wall of the insulating tube during the main discharge, and the life of the surge absorber can be prolonged. Further, since the oxide film has excellent adhesion to the main discharge surface, the above characteristics can be exhibited reliably. Further, since it is not necessary to use a high-priced metal having excellent chemical stability in a high temperature region as the metal member, an inexpensive metal can be used as the material of the metal member.

In the surge absorber, the average thickness of the oxide film is preferably 0.01 μm or more.

In this surge absorber, since the average thickness of the oxide film is 0.01 μm or more, scattering of the electrode component of the metal member due to main discharge can be sufficiently suppressed.

In the surge absorber, it is preferable that a holding portion that is formed to protrude from the terminal electrode toward the inside of the insulating tube in the axial direction and holds the insulating member is provided.

In this surge absorber, since the holding member is used for holding, the insulating member is reliably disposed in the vicinity of the center of the terminal electrode and the peripheral portion thereof. As a result, the discharge start voltage is stabilized, and the insulating member is prevented from being displaced to the end portion side of the terminal electrode, so that the life of the surge absorber can be extended.

In the surge absorber, the pressure of the seal gas is preferably a negative pressure.

In this surge absorber, since the pressure of the sealing gas is a negative pressure, when the sealed insulating tube is cooled, a force in the compression direction is generated in the terminal electrode due to the action of the atmospheric pressure higher than the pressure of the sealing gas, and the conductive film is brought into contact with the terminal electrode by the force in the compression direction, whereby more reliable ohmic contact can be obtained.

Further, a surge absorber of the present invention is characterized by being provided with: a columnar insulating member formed by dividing the conductive film with a discharge gap interposed therebetween on the peripheral surface; a pair of terminal electrodes facing the conductive coating at both ends of the insulating member; and an insulating tube having the pair of terminal electrodes disposed at both ends thereof by soldering with solder, the insulating tube sealing the insulating member inside together with a sealing gas; the conductive film and the terminal electrode are bonded by a conductive adhesive used as a conductive portion.

In this surge absorber, the terminal electrode and the conductive coating are bonded together with a conductive adhesive, so that sufficient ohmic contact between the terminal electrode and the conductive coating can be obtained, and the electrical characteristics such as the discharge start voltage of the surge absorber can be stabilized. Further, by fixing the insulating member near the center and the peripheral portion of the terminal electrode, the discharge start voltage can be stabilized, and the life of the surge absorber can be extended.

Further, a surge absorber of the present invention is characterized by comprising: a columnar insulating member formed by dividing the conductive film with a discharge gap interposed therebetween on the peripheral surface; a pair of terminal electrodes facing the conductive coating at both ends of the insulating member; and an insulating tube having the pair of terminal electrodes disposed at both ends thereof and sealed therein together with a sealing gas by welding with a solder; a metal member is provided between the conductive film and the terminal electrode, and the metal member and the terminal electrode are bonded together with a conductive adhesive serving as a conductive portion.

In this surge absorber, by bonding the terminal electrode and the metal member with a conductive adhesive, sufficient ohmic contact between the terminal electrode and the metal member can be obtained, and the electrical characteristics such as the discharge start voltage of the surge absorber can be stabilized. Further, by fixing the insulating member near the center and the peripheral portion of the terminal electrode, the discharge start voltage can be stabilized, and the life of the surge absorber can be extended.

In the surge absorber, it is preferable that an oxide film generated by oxidation is formed on a main discharge surface which is a surface of the pair of metal members facing each other.

In this surge absorber, an abnormal current and an abnormal voltage such as an electrical surge that enters from the outside trigger discharge at the micro gap, and main discharge is performed between main discharge surfaces that are surfaces of the pair of metal members facing each other, thereby absorbing the surge. Here, since the oxide film is formed on the main discharge surface, the main discharge surface having excellent chemical stability in a high temperature region can be obtained. Therefore, the electrode component on the main discharge surface is prevented from scattering and adhering to the micro-gap and the inner wall of the insulating tube during the main discharge, and the life of the surge absorber is extended. Further, since the adhesion between the oxide film and the main discharge surface is good, the above characteristics can be exhibited reliably. Further, since it is not necessary to use a high-priced metal having excellent chemical stability in a high-temperature region as the metal member, an inexpensive metal can be used as the material of the metal member.

In the surge absorber, the average thickness of the oxide film is preferably 0.01 μm or more.

In this surge absorber, since the average thickness of the oxide film is 0.01 μm or more, scattering of the electrode component of the metal member due to main discharge can be sufficiently suppressed.

In the surge absorber, the solder and the adhesive are preferably formed of different materials.

In this surge absorber, since the solder and the adhesive are formed of different materials, a material having an optimum adhesive strength can be selected for adhesion of the terminal electrode to the conductive coating film, adhesion of the terminal electrode to the metal member, or adhesion of the terminal electrode to the insulating tube.

Further, the surge absorber is preferably provided with: and a holding member formed to protrude from the terminal electrode toward the inside of the insulating tube in the axial direction and holding the insulating member.

In this surge absorber, the insulating member is held by the holding member and is reliably disposed near the center and the peripheral portion of the terminal electrode. As a result, the discharge start voltage is stabilized, and the insulating member is prevented from being displaced to the end portion side of the terminal electrode, thereby realizing a long life of the surge absorber.

The holding member is preferably formed of a material different from the adhesive, the material being the same as the solder.

Alternatively, the holding member is preferably formed of a material different from the solder, the material being the same as the adhesive.

In this surge absorber, the holding member and the solder or the adhesive are formed of the same material, so that the number of parts can be reduced and the surge absorber can be easily manufactured.

Alternatively, the holding member is preferably formed of a material different from the adhesive and the solder.

In this surge absorber, since the holding member is made of a material that is difficult to wet with the conductive film, the metal member, the terminal electrode, the adhesive, and the solder, the height of the holding member is increased when the sealed insulating tube is cooled. Thus, the insulating member can be fixed more stably.

In the surge absorber, the pressure of the seal gas is preferably a negative pressure.

In this surge absorber, since the pressure of the sealing gas is a negative pressure, when the sealed insulating tube is cooled, a force in the compression direction is generated in the terminal electrode by the atmosphere having a pressure higher than the pressure of the sealing gas. By bringing the conductive film into contact with the terminal electrode by the force in the compression direction, more reliable ohmic contact can be obtained.

Further, the surge absorber of the present invention is characterized in that: a columnar or plate-shaped insulating member formed by dividing the conductive film with a discharge gap interposed therebetween on the peripheral surface; a pair of terminal electrodes facing the conductive coating at both ends of the insulating member; and an insulating tube which is provided with the pair of terminal electrodes at both ends thereof and seals the insulating member inside together with a sealing gas; a conductive buffer member is provided as the conductive portion between the conductive film and the terminal electrode.

According to this surge absorber, the conductive buffer member is provided between the end face of the conductive film and the terminal electrode, and the buffer member is compressed to absorb dimensional tolerance, so that the end face of the conductive film and the terminal electrode can be reliably connected through the buffer member. Therefore, a high-quality surge absorber having stable discharge performance, which can reliably pass a surge current between the conductive film and the terminal electrode, can be manufactured at low cost without strict dimensional tolerance management.

The above-described arrangement of the buffer member is particularly suitable for a surge absorber in which terminal electrodes are bonded to both end surfaces of an insulating tube.

As the cushioning member, any of a metal plate, a metal foil, a foamed metal, a fiber metal, and a solder may be used.

Preferably, the buffer member is provided with a raised portion for holding the outer peripheral surfaces of both ends of the insulating member.

Since the insulating member is reliably fixed by providing the buffer member with the bulging portions that hold the outer peripheral surfaces of both ends of the insulating member, a surge absorber having a stable discharge start voltage can be obtained even in a use environment affected by, for example, vibration.

In addition, the method for manufacturing the surge absorber is characterized by comprising the following steps: a columnar or plate-shaped insulating member formed by dividing the conductive film with a discharge gap interposed therebetween on the peripheral surface; a pair of terminal electrodes facing the conductive coating on both end surfaces of the insulating member; and an insulating tube which is provided with the pair of terminal electrodes at both ends thereof and seals the insulating member inside together with a sealing gas; the buffer member is provided between the end surface of the conductive film inserted into the insulating tube and the terminal electrode, and the terminal electrode is bonded to both ends of the insulating tube.

According to the method of manufacturing the surge absorber, the buffer member is compressed by being pressed by the terminal electrode, so that dimensional tolerances can be absorbed, and the end face of the conductive film and the terminal electrode are reliably connected through the buffer material. Therefore, a high-quality surge absorber having stable discharge performance, which can reliably flow a surge current between the end surface of the conductive film and the terminal electrode, can be manufactured at low cost without strict dimensional tolerance management.

Brief description of the drawings

Fig. 1(a) is a sectional view showing a surge absorber according to embodiment 1 of the present invention.

Fig. 1(B) is a sectional view showing a 1 st modification of a surge absorber according to 1 st embodiment of the present invention.

Fig. 1(C) is a cross-sectional view showing a 2 nd modification of a surge absorber according to 1 st embodiment of the present invention.

Fig. 2 is an exploded perspective view of the surge absorber shown in fig. 1A.

Fig. 3A is a perspective view showing a surge absorbing element in a surge absorber according to embodiment 2 of the invention.

Fig. 3B is a partial cross-sectional view of fig. 3A.

Fig. 4 is a sectional view showing a surge absorber according to embodiment 3 of the present invention.

Fig. 5A is a sectional view showing a surge absorber according to embodiment 4 of the present invention.

Fig. 5B is an enlarged view of a contact portion of the terminal electrode and the cylindrical ceramic in fig. 5A.

Fig. 6 is a sectional view of a surge absorber of the present invention mounted on a substrate.

Fig. 7A is a sectional view showing a surge absorber according to embodiment 5 of the present invention.

Fig. 7B is an enlarged view of a contact portion of the terminal electrode and the cylindrical ceramic in fig. 7A.

Fig. 8A is a sectional view showing a surge absorber according to embodiment 6 of the present invention.

Fig. 8B is an enlarged view of a contact portion of the terminal electrode and the cylindrical ceramic in fig. 8A.

Fig. 9A is a sectional view showing a surge absorber according to embodiment 7 of the present invention.

Fig. 9B is an enlarged view of a contact portion of the terminal electrode and the cylindrical ceramic in fig. 9A.

Fig. 10 is a sectional view of an example of a conventional surge absorber.

Best mode for carrying out the invention

A surge absorber and a method of manufacturing the surge absorber according to embodiment 1 of the present invention will be described below with reference to fig. 1A and 2. Fig. 1A is a sectional view of the surge absorber, and fig. 2 is an exploded perspective view of fig. 1A.

The surge absorber 10 of the present embodiment is a discharge type surge absorber using a so-called micro gap, and the surge absorbing element 11 is housed in a cylindrical ceramic (insulating tube) 15 together with a sealing gas, and terminal electrodes 16 are bonded to end surfaces 15a at both ends of the insulating tube 15, respectively, to seal the cylindrical ceramic 15.

The cylindrical ceramic 15 is formed by molding an insulating member such as ceramic or lead glass into a hollow quadrangular prism shape. The surge absorbing element 11, which will be described later, is housed in the hollow portion 15b of the cylindrical ceramic 15 together with the sealing gas G, and both end portions 15a of the cylindrical ceramic 15 are sealed with a pair of terminal electrodes 16. That is, the hollow portion 15b is configured as a hermetic chamber in which the surge absorbing element 11 and the sealing gas G are sealed.

Further, both end surfaces 15a of the cylindrical ceramics 15 are plated with Ni (nickel) after metallization of Mo (molybdenum) -Mn (manganese), for example. The metallization of both end faces 15a is not limited to Mo (molybdenum) -Mn (manganese), and may be, for example, Mo-W (tungsten), Ag (silver), Cu (copper), Au (gold), or the like, and may not be nickel-plated. Alternatively, a metalized layer may be formed on both end surfaces 15a using an active silver solder or glass instead.

Here, examples of the insulating member that can be used for the cylindrical ceramic 15 include: al (Al)₂O₃(alumina), ZrO₂(zirconia), glass-ceramic, Si₃N₄Insulating ceramics such as (silicon nitride), AlN (aluminum nitride), and SiC (silicon carbide).

The sealing gas to be used may contain air as long as it is ionized at a high temperature, but if stability at a high temperature is taken into consideration, for example: he (helium), Ar (argon), Ne (neon), Xe (xenon), SF₆、CO₂(carbon dioxide) C₃F₈、C₂F₆、CF₄、H₂1 or 2 or more kinds of mixed gas such as (hydrogen).

The surge absorbing element 11 has a structure in which: a conductive coating 12 of a thin film of Ti (titanium) or the like is coated on the entire surface of a cylindrical ceramic (insulating member) 13, and a micro gap M as a discharge gap is formed on the entire surface.

The micro gap M is a portion where the conductive film 12 is removed in the circumferential direction in the vicinity of the center in the axial direction of the cylindrical ceramic 13 and the cylindrical ceramic 13 is exposed on the circumferential surface. As a result, the conductive film 12 is divided into two by the micro gap to be electrically insulated. The discharge gap M can be formed by laser cutting, mechanical cutting, etching, or the like. Furthermore, the discharge gaps M are formed in the width of about 0.01 to 1.5mm by about 1to 100 strips.

The cylindrical ceramics 13 is an insulating ceramics made of, for example, a mullite sintered body, and in addition to this, for example: al (Al)₂O₃(alumina), ZrO₂(zirconia), glass-ceramic, Si₃N₄Insulating ceramics such as (silicon nitride), AlN (aluminum nitride), and SiC (silicon carbide).

In addition, Physical Vapor Deposition (PVD) or Chemical Vapor Deposition (CVD) may be used to form the conductive film 12. In addition to the Ti film described above, for example: SnO₂(TiN oxide), TiCN (titanium carbonitride), Ag (silver)/Pd (palladium), Al (aluminum), Ni (nickel), Cu (copper), TiN (titanium nitride), Ta (tantalum), W (tungsten), SiC (silicon carbide), BaAl, C (carbon), Ag (silver)/Pt (platinum), TiO (titanium nitride), titanium nitride, titanium₂A conductive film 12 such as titanium oxide (TiO) or TiC (titanium carbide).

The surge absorbing element 11 having the above-described structure is inserted into the hollow portion 15b of the cylindrical ceramic 15, and then the terminal electrodes 16 are bonded to the both end surfaces 15a to seal them together with the sealing gas, and at this time, a conductive cushioning member (conductive portion) 17 is provided between the end surface 11a of the surge absorbing element 11 and the terminal electrodes 16. Since the cushioning member 17 is a member including a fixing material, a supporting material, and a material that is easily deformable, they will be collectively referred to as "cushioning members" in the following description.

As the electrode material constituting the terminal electrode 16, Cu (copper) based, Ni (nickel) based alloy materials, and the like can be used, in addition to kovar (registered trademark), for example. The terminal electrode 16 is connected to a surge protection circuit or the like. Further, the terminal electrode 16 may be sealed by soldering, glass, or the like.

The cushioning member 17 is a conductive member having appropriate elasticity, and for example, any one of a metal plate, a metal foil, a foamed metal, a fiber metal, and a solder may be used.

Specific examples of the metal plate or the metal foil include: ag (silver), Cu (copper), Al (aluminum), Au (gold), Ni (nickel), Pd (palladium), Sb (antimony), Zn (zinc), In (indium), Sn (tin), Pb (lead), Bi (bismuth), Ti (titanium), stainless steel materials, and alloys containing 2 or more of the above metals.

The foamed metal may be a metal in a porous state, or a metal having a property of being pressed and deformed by the columnar ceramic 13 forming the micro gap M when the cylindrical ceramic 15 and the terminal electrode 16 are bonded. Specific examples of the metal foam include Ni (nickel), Cu (copper), Al (aluminum), Mg (magnesium), Co (cobalt), W (tungsten), Mn (manganese), Cr (chromium), Be (beryllium), Ti (titanium), Au (gold), Ag (silver), Fe (iron), stainless steel, carbon steel, Fe (iron) alloy, and Ni (nickel alloy).

The fiber metal may be a metal having a property of being compressed and deformed by the cylindrical ceramic 13 forming the micro gap M when the cylindrical ceramic 15 and the terminal electrode 16 are bonded to each other, and the metal may be a metal having a cushioning property by weaving a wire-shaped metal. As a specific fiber metal, fiber metals such as Ti (titanium), Al (aluminum), C (carbon), stainless steel, etc. are known, and fiber metals made of a metal used for the above metal plate or metal foil or an alloy of 2 or more kinds may be used.

Further, examples of the solder suitable for the cushioning member 17 include: ag (silver) -Cu (copper), Ag (silver) -Cu (copper) -In (indium), Ag (silver) -Cu (copper) -Sn (tin), and the like.

In the surge absorber 10 having the above-described structure, since the space between the end surface 11a of the surge absorbing element 11 and the terminal electrode 16 is sealed in a compressed state of the cushioning member 17, a gap is not likely to exist, and electricity can be conducted by reliably contacting. That is, since the dimensional error between the surge absorbing element 11 and the cylindrical ceramic 15 can be absorbed by the deformation of the buffer member 17, no gap is generated between the end surface 11a on which the conductive film 12 is formed and the terminal electrode 16.

Therefore, stable discharge performance with little variation among products can be obtained, and a surge absorber 10 of high quality in terms of durability and reliability can be manufactured. In addition, since the dimensional tolerances of the surge absorbing element 11 and the cylindrical ceramic 15 are relaxed, the effect of reducing the manufacturing cost can be obtained.

In the embodiment shown in fig. 1A, the surge absorbing element 11 and the cushioning member 17 are configured to be in direct contact with each other, but may be configured as in the 1 st modification shown in fig. 1B or the 2 nd modification shown in fig. 1C.

In a surge absorber 10' of modification 1 shown in fig. 1B, a buffer member 17 is provided so as to be expanded in the circumferential direction and sandwiched between an end face 15a of a cylindrical ceramic 15 and a terminal electrode 16.

In a surge absorber 10 ″ of modification 2 shown in fig. 1C, cap electrodes 18 are press-formed at both ends of the surge absorbing element 11 in modification 1.

Hereinafter, a 2 nd embodiment having the above-described cushioning member 17 will be described with reference to fig. 3. The same portions as those in the above embodiments are denoted by the same reference numerals, and detailed description thereof is omitted.

In the present embodiment, cushioning members 17A are integrally provided on both end surfaces of the surge absorbing element 11A instead of the separate cushioning members 17. The cushioning member 17A is formed by bonding or the like to both end surfaces of the surge absorbing element 11A manufactured in the same manner as in the above-described embodiment.

At this time, since the number of individual members is reduced by inserting the surge absorbing element 11A into the hollow portion 15b of the cylindrical ceramic 15, the assembly work of the surge absorber 10 sealed with the terminal electrode 16 together with the sealing gas G becomes easy.

Further, since the buffer member 17A is present, the contact with the terminal electrode becomes reliable, and a stable discharge start voltage can be obtained.

Next, a 3 rd embodiment in which the above-described cushioning member 17 is provided will be described with reference to fig. 4. The same portions as those in the above embodiments are denoted by the same reference numerals, and detailed description thereof is omitted.

In the present embodiment, cap electrodes 18 are press-formed on both ends of the surge absorbing element 11. Further, a buffer member 17B is provided between the cap electrode 18 and the terminal electrode 16. The cushioning member 17B is provided with a raised portion 19 having a height h so as to hold the outer peripheral surface of the cap electrode 18 at both ends of the surge absorbing element 11. That is, both end portions (in this case, the cap electrodes 18) of the surge absorbing element 11 are held so as to be embedded in the cushioning members 17B of the swelling portions 19 formed by melting. The height of the bump 19 is a dimension from the end surface of the terminal electrode 16 to the uppermost portion of the bump.

Further, if solder is used for the cushion material 17B, both end surfaces 15a of the tubular member 15 and the terminal electrode 16 can be sealed while holding the surge absorbing element. In the case of using the surge absorbing element 11 (see fig. 1A and 1B) without the cap electrode 18, the ridge portions 19 having the height h may be provided so as to hold the outer peripheral surfaces of both ends.

In this way, if the structure is adopted in which both ends of the surge absorbing element 11 are held by the ridge portions 19, the surge absorbing element can be reliably fixed in addition to the function as the cushioning material. Thus, since the surge absorbing element 11 and the terminal electrode 16 are reliably and stably contacted through the buffer material, the discharge start voltage is stabilized.

In addition, since the swell having a height h of at least 0.01mm or more is provided, it is experimentally confirmed that the surge absorbing element can be reliably fixed even in a use environment where vibration occurs.

In the surge absorber 10 described above, the cylindrical ceramic 15 is a cylindrical quadrangular prism, but the present invention is not limited to this, and may be a cylindrical cylinder, a triangular prism, or a polygonal prism, for example. The surge absorbing element 11 based on the cylindrical ceramic 13 is not limited to a cylindrical shape, and may be in various columnar shapes such as a quadrangular prism, a plate shape, or the like, and may be appropriately selected together with the shape of the cylindrical ceramic 15.

The structure of the present invention is not limited to the above-described embodiments, and for example, a mode in which a buffer member is provided between a cap electrode and a terminal electrode, both ends of which are press-molded, may be appropriately modified within a range not exceeding the gist of the present invention.

Hereinafter, a surge absorber 4 th embodiment of the present invention will be described with reference to fig. 5A and 5B.

Surge absorber 21 of the present embodiment is a discharge type surge absorber using a micro gap, in which: a cylindrical ceramic (insulating member) 24 formed by dividing the conductive coating 23 on the peripheral surface with the discharge gap 22 at the center interposed therebetween; a pair of terminal electrodes 25 in contact with the conductive films 23 disposed to face each other at both ends of the columnar ceramic 24; and a cylindrical ceramic (insulating tube) 27 in which the pair of terminal electrodes are disposed at both ends and a cylindrical ceramic 24 is sealed inside together with a sealing gas 26 such as Ar (argon), for example, and the composition of the sealing gas 26 is adjusted to obtain desired electrical characteristics.

The columnar ceramics 24 is formed of an insulating ceramic material such as a sintered mullite body, and a thin film of TiN (titanium nitride) or the like is formed on the surface as a conductive coating by a thin film forming technique such as a Physical Vapor Deposition (PVD) method or a Chemical Vapor Deposition (CVD) method.

The discharge gaps 22 having a width of from 0.01 to 1.5mm and a number of from 1to 100, but 1 in this embodiment of 150 μm, are formed by machining such as laser cutting, mechanical cutting, etching, or the like.

The pair of terminal electrodes 25 are formed of a metal such as kovar (registered trademark) alloy, which is an alloy of Fe (iron), Ni (nickel), and Co (cobalt).

The pair of terminal electrodes 25 have outer edge portions 25A respectively connected to end surfaces 27A of the cylindrical ceramics 27, and silver-containing solder 28 is applied to one surface thereof.

The solder 28 includes: a filling part (filler) 210 serving as a conductive part for filling the gap 29 formed at the contact surface between the pair of terminal electrodes 25 and the end surface 24a of the cylindrical ceramic 24; and holding portions (holding members) 211 for holding the outer peripheral surface of the cylindrical ceramic 24 at both ends of the cylindrical ceramic 24. This gap 29 is a gap formed by a projection and a recess between the pair of terminal electrodes 25 and the cylindrical ceramic 24 due to dimensional accuracy, a flaw, deformation at the time of processing, and the like.

The holding portion 211 is formed by a ridge for covering the outer peripheral surface of the cylindrical ceramics with the solder 28 when the terminal electrode 25 is in contact with the cylindrical ceramics 24.

The height h of the protrusion of the holding portion 211 is a dimension from the end surface of the terminal electrode 25 to the uppermost portion of the protrusion, and the uppermost portion is a main discharge portion and is defined according to a predetermined life characteristic.

The cylindrical ceramic 27 has a rectangular cross section, and the outer dimensions of both end faces are matched with the outer dimensions of the terminal electrode 25. The cylindrical ceramic 27 is made of, for example, Al₂O₃An insulating ceramic such as (alumina) is formed by metallizing both end surfaces with Mo (molybdenum) -W (tungsten), for example, and then forming a metallized layer by plating Ni (nickel).

A method for manufacturing the sheet-type surge absorber 21 of the present embodiment having the above configuration will be described below.

First, a sufficient amount of solder 28 for forming the holding portion 211 is applied to one surface of the terminal electrode 25, and the cylindrical ceramic 24 is placed on the central region of the terminal electrode to bring the terminal electrode 25 into contact with the cylindrical ceramic 24. Then, the end face of the cylindrical ceramic 27 is placed on the outer edge portion 25A.

Further, solder 28 is provided on the other end face of the cylindrical ceramic 27, and the other terminal electrode 25 is placed thereon as a state of temporary bonding.

Next, a sealing step of sealing the cylindrical ceramic 24 together with Ar gas by the pair of terminal electrodes 25 and the cylindrical ceramic 27 will be described.

The element in the temporarily joined state as described above is heated in an Ar (argon) atmosphere, and the solder is melted to bond the terminal electrode 25 and the cylindrical electrode ceramic 27. At this time, the solder 28 melts to fill the filling portion 210, that is, the gap 29 between the end face 24a of the columnar ceramic 24 and the terminal electrode 25. The holding portion 211 formed by the surface tension of the solder 28 embeds and holds both end portions of the columnar ceramic 24.

Here, the pressure of the sealing gas 26 is set in the range of 1Torr to 600Torr in the cooling step. Therefore, in the cooling step, a force in the compression direction is generated in the terminal electrode 25.

Thereafter, Ni (nickel) and Sn (tin) plating was performed to produce a chip-type surge absorber 21.

As shown in the example of fig. 6, the surge absorber 21 thus manufactured can be used by placing a mounting surface 27B, which is one side surface of the cylindrical ceramic 27, on a substrate B such as a printed circuit board, and fixing the outer surfaces of the substrate B and the pair of terminal electrodes 25 by soldering with solder S.

According to this surge absorber 21, the gap 29 formed at the contact surface between the terminal electrode 25 and the end surface 24a of the columnar ceramic 24 due to dimensional accuracy, scratches, deformation during processing, or the like is filled with the solder serving as a conductive filler, so that the contact area between the terminal electrode 25 and the columnar ceramic 24 is increased. As a result, sufficient ohmic contact between the terminal electrode and the conductive film 23 can be obtained, and the electrical characteristics such as the discharge start voltage of the surge absorber 21 can be stabilized.

Further, by fixing the columnar ceramic 24 to the vicinity of the center and the peripheral portion of the terminal electrode 25 by the holding portion 211, the discharge start voltage can be stabilized, and the life of the surge absorber 21 can be prolonged.

Further, since the pressure of the sealing gas 26 sealed between the pair of terminal electrodes 25 and the cylindrical ceramics 27 is 1Torr to 600Torr, a force in the direction of compressing the terminal electrodes 25 is generated, and the ohmic contact between the terminal electrodes 25 and the conductive film is more secured, and after the cooling step is completed, the slow leakage of the air flowing in from between the terminal electrodes 25 and the cylindrical ceramics 27 can be avoided.

Hereinafter, a surge absorber according to embodiment 5 of the present invention will be described with reference to fig. 7A and 7B.

The basic configuration of the embodiment described here is the same as that of embodiment 4 described above, and the embodiment 4 described above is configured with other elements added. In fig. 7A and 7B, the same components as those in fig. 5A and 5B are denoted by the same reference numerals, and description thereof will be omitted.

Embodiment 4 differs from embodiment 5 in that surge absorber 21 in embodiment 4 is configured such that cylindrical ceramic 24 directly contacts terminal electrode 25, and surge absorber 220 in embodiment 5 is configured such that cylindrical ceramic 24 contacts terminal electrode 25 via a pair of cap electrodes (metal members) 221 formed in a bowl shape.

The pair of cap electrodes 221 are lower in hardness than the cylindrical ceramics 24 and can be plastically deformed, and are made of metal such as stainless steel, for example, and the outer peripheral portions thereof are formed with a substantially U-shaped cross section.

Then, an oxide film 222 having an average film thickness of 0.01 μm or more is formed on the surfaces of the pair of cap electrodes 221 by an oxidation process.

The solder 28 includes: a filling section 210 for filling a gap 29 formed at a contact surface between the pair of terminal electrodes 25 and the end surface 221a of the cap electrode 221; and holding portions 211 that hold the outer peripheral surface of the cap electrode 221 at both ends of the cap electrode 221. In addition, the height h of the holding portion 211 is formed to be lower than the height of the cap electrode 221. Accordingly, the surfaces of the cap electrodes 221 facing each other serve as main discharge surfaces 221A.

A method for manufacturing surge absorber 220 having the above-described structure will be described below.

First, an oxide film 222 having an average thickness of 0.01 μm or more is formed on the surfaces of the pair of cap electrodes 221 by performing an oxidation treatment at 500 ℃ for 30 minutes in the atmosphere, for example.

Then, a pair of cap electrodes 221 are fitted to both ends of the cylindrical ceramic 24, and a surge absorber 220 is manufactured by the same method as in example 4.

This surge absorber 220 has the same operation and effect as those of the surge absorber 1 of embodiment 4 described above, and since the oxide film 222 having an average film thickness of 0.01 μm or more is formed on the cap electrode 221 by the oxidation treatment, the main discharge surface 221A can have a chemically (thermodynamically) stable characteristic in a high temperature region. Further, since the adhesion between the oxide film 222 and the cap electrode 221 is good, the characteristics of the oxide film 222 can be sufficiently exhibited. Therefore, even if the cap electrode 221 is at a high temperature during the main discharge, scattering of the metal component of the cap electrode to the micro-gap 222, the inner wall of the cylindrical ceramic 227, and the like can be sufficiently suppressed. As a result, the life of the surge absorber can be extended.

The present invention is not limited to the above-described embodiments, and various modifications can be made without departing from the scope of the present invention.

For example, the conductive coating may be Ag (silver), Ag (silver)/Pd (palladium) alloy, SnO₂(tin oxide), Al (aluminum), Ni (nickel), Cu (copper), Ti (titanium), Ta (tantalum), W (tungsten), SiC (silicon carbide), BaAl, C (carbon), Ag (silver)/Pt (platinum) alloy, TiO (titanium carbide), titanium dioxide, and the like₂Titanium oxide, TiC (titanium carbide), TiCN (titanium carbonitride), and the like.

The terminal electrode may be made of Cu (copper) or Ni (nickel) alloy, and the metalized layers on both end surfaces of the cylindrical ceramic may be made of Ag (silver), Cu (copper), or Au (gold).

In addition, the composition of the sealing gas may be adjusted to obtain desired electrical characteristics, and may be, for example, the atmosphere, or Ar (argon), N₂(Nitrogen), Ne (Neon), He (helium), Xe (xenon), H₂(hydrogen), SF₆、CF₄、C₂F₆、C₃F₈、CO₂(carbon dioxide) and a mixed gas thereof.

Hereinafter, a surge absorber according to embodiment 6 of the present invention will be described with reference to fig. 8A and 8B.

Surge absorber 31 of the present embodiment is a discharge type surge absorber using a so-called micro gap, in which: a cylindrical ceramic (insulating member) 34 formed by dividing the conductive coating 33 with a central discharge gap 32 interposed therebetween on the peripheral surface; a pair of terminal electrodes 35 disposed opposite to each other at both ends of the columnar ceramic 34 and in contact with the conductive film 33; and a cylindrical ceramic (insulating tube) 37 in which the pair of terminal electrodes 35 are disposed at both ends, and the cylindrical ceramic 34 is sealed together with a sealing gas 36 such as Ar (argon), and the composition and the like of the sealing gas 36 are adjusted to obtain desired electrical characteristics and the like.

The columnar ceramic 34 is made of a ceramic material such as a sintered mullite body, and a thin film of TiN (titanium nitride) or the like is formed as the conductive coating 33 on the surface thereof by a thin film forming technique such as a Physical Vapor Deposition (PVD) method or a Chemical Vapor Deposition (CVD) method.

The discharge gaps 32 having a width of 0.01 to 1.5mm and a number of 1to 100 are formed by laser cutting, mechanical cutting, etching, or the like, but 1 stripe having a width of 150 μm is formed in this embodiment.

The pair of terminal electrodes 35 are formed of kovar (registered trademark) which is an alloy of Fe (iron), Ni (nickel), and Co (cobalt), and each has a peripheral edge portion 35A bonded to an end surface 37A of the cylindrical ceramic 37 with a solder 38 made of Ag (silver) -Cu (copper).

The pair of terminal electrodes 35 and the end surface 34a of the columnar ceramic 34 are bonded to each other with an active silver solder (conductive portion) 39 of a conductive adhesive made of Ag (silver) -Cu (copper) -Ti (titanium).

The outer peripheral surfaces of both ends of the columnar ceramics 34 are held by a glass material (holding portion) 310 that is less wettable to the conductive film 33, the terminal electrode 35, the solder 38, and the active silver solder 39. The height h of the glass material 310 from the end face of the terminal electrode 35 to the uppermost portion of the ridge is equal to or greater than the average thickness of the solder, and is used to sufficiently fix the cylindrical ceramic 34.

The cylindrical ceramic 37 has a rectangular cross section, and the outer dimensions of both end faces are matched with the outer dimensions of the terminal electrode 35. The cylindrical ceramic 37 is made of, for example, Al₂O₃An insulating ceramic such as (alumina) is formed by metallizing both end surfaces with Mo (molybdenum) -W (tungsten), for example, and then plating Ni (nickel) to form a metallized layer.

A method for manufacturing the sheet-type surge absorber 31 of the present embodiment having the above configuration will be described below.

First, the active silver solder 39 is applied to the central region of the terminal electrode 35, and the cylindrical ceramics 34 is placed on the central region, so that the terminal electrode 35 is in contact with the cylindrical ceramics 34. Then, a glass material 310 is applied to the peripheral portion of the central region. Further, the outer edge portion 35A is coated with a solder 38, and the end face of the cylindrical ceramic 37 is placed on the outer edge portion 35A.

Further, solder 38 is provided on the other end face of the cylindrical ceramic 37, and the other terminal electrode 35 similarly coated with the active silver solder 39, the glass material 310 and the solder 38 is placed thereon to form a temporarily joined state.

Next, a sealing process for sealing the cylindrical ceramic 34 inside together with Ar (argon) gas by the pair of terminal electrodes 35 and the cylindrical ceramic 37 will be described.

The temporarily joined elements are heat-treated in an Ar (argon) atmosphere to melt the solder 38, the active silver solder 39, and the glass material 310. The terminal electrode 35 is bonded to the cylindrical ceramic 37 by melting the solder 38. In addition, the terminal electrode 35 is bonded to the cylindrical ceramics 34 by melting the active silver solder 39. Then, since the glass material 310 is melted, the ridge portion formed by the glass material 310 embeds and holds both end portions of the cylindrical ceramic 34.

Here, the pressure of the sealing gas 36 is set in the range of 1Torr to 600Torr in the cooling step. Therefore, in the cooling step, a force in the compression direction is generated in the terminal electrode 35.

Thereafter, the chip-type surge absorber 31 is made by Ni (nickel) plating and Sn (tin) plating.

As with surge absorber 21 of embodiment 4, surge absorber 31 thus manufactured is used, for example, as shown in fig. 6, by placing mounting surface 37B, which is one side surface of cylindrical ceramic 37, on substrate B such as a printed circuit board, and soldering the outer surfaces of substrate B and the pair of terminal electrodes 35 with solder S.

According to this surge absorber 31, the terminal electrode 35 and the cylindrical ceramics 34 are reliably brought into contact by bonding the terminal electrode 35 and the end face 34a of the cylindrical ceramics 34 with the activated silver solder 39. Therefore, sufficient ohmic contact between the terminal electrode 35 and the conductive film 33 can be obtained, and the electrical characteristics such as the discharge start voltage of the surge absorber 31 can be stabilized.

Further, by fixing the glass material 310 for the cylindrical ceramic 34 to the central portion and the peripheral portion of the terminal electrode, the discharge start voltage can be stabilized, and the life of the surge absorber 31 can be extended. Here, since it is difficult for the glass material 310 to wet the conductive coating 33, the terminal electrode 35, the solder 38, and the active silver solder 39, the columnar ceramics 34 are reliably fixed.

Further, by setting the pressure of the sealing gas 36 sealed between the pair of terminal electrodes 35 and the cylindrical ceramics 37 to 1Torr to 600Torr, a force in the compression direction is generated in the terminal electrodes 35, so that the ohmic contact between the terminal electrodes 35 and the conductive coating 33 can be more reliably made, and the slow leakage of the air flowing in from between the terminal electrodes 35 and the insulating tube 34 after the cooling step is completed can be avoided.

In the present embodiment, the holding member for holding the columnar ceramics 34 may be made of the same material as the solder material 38 or the active silver solder 39. At this time, the uppermost portion of the height h of the bulge is defined according to a predetermined life characteristic since it is the main discharge portion.

Hereinafter, a 7 th embodiment of a surge absorber according to the present invention will be described with reference to fig. 9A and 9B.

The embodiment described here is the same as embodiment 6 described above in basic configuration, but other elements are added to embodiment 6 described above. Therefore, in fig. 9A and 9B, the same components as those in fig. 8A and 8B are denoted by the same reference numerals, and the description thereof will be omitted.

Embodiment 7 differs from embodiment 6 in that, corresponding to the structure in which the cylindrical ceramic 34 of the surge absorber 31 in embodiment 6 is in direct contact with the terminal electrode 35, in the structure of the surge absorber 320 in embodiment 7, the cylindrical ceramic 34 is in contact with the terminal electrode 35 via a pair of cap electrodes (metal members) 321 formed in a bowl shape.

The pair of cap electrodes 321 are lower in hardness than the cylindrical ceramics and can be plastically deformed, and are made of metal such as stainless steel, for example, and the outer peripheral portions thereof are formed in a substantially U-shaped cross section.

Then, an oxide film 322 having an average film thickness of 0.01 μm or more is formed on the surfaces of the pair of cap electrodes 321 by oxidation treatment. The surface of the cap electrode 321 facing each other is a main discharge surface 321A.

The height h of the glass material 310 is equal to or greater than the average thickness of the solder 38 to sufficiently fix the cylindrical ceramics 34 and the cap electrode 321, as in the above-described embodiment 6

A method of manufacturing surge absorber 320 of the present embodiment formed of the above structure will be described below.

First, an oxide film 322 having an average film thickness of 0.01 μm or more is formed on the surfaces of the pair of cap electrodes 321 by performing an oxidation treatment at 500 ℃ for 30 minutes in the atmosphere, for example.

Then, a pair of cap electrodes 321 are fitted to both ends of the columnar ceramic 34, and a surge absorber 320 is manufactured by the same method as in embodiment 6.

This surge absorber 320 has the same action and effect as those of the surge absorber 31 according to embodiment 6 described above, and the main discharge surface 321A can be provided with chemically (thermodynamically) stable characteristics in a high temperature region by forming the oxide film 322 having an average film thickness of 0.01 μm or more by the oxidation treatment cap electrode 321. Further, since the adhesion between the oxide film 322 and the cap electrode is good, the characteristics of the oxide film 322 can be sufficiently exhibited. Therefore, even if the cap electrode 321 is at a high temperature during the main discharge, scattering of the metal component of the cap electrode 321 to the inner walls of the micro-gap 32 and the cylindrical ceramic 37 can be sufficiently suppressed. As a result, the life of the surge absorber is extended.

In this embodiment, as in embodiment 6 described above, the holding member for holding the columnar ceramics 34 may be made of the same material as the solder 38 or the activated silver solder 39. At this time, the height h of the ridge portion is formed lower than the height of the cap electrode, and the main discharge surface 321A serves as a main discharge portion.

The present invention is not limited to the above-described embodiments, and various modifications can be made without departing from the scope of the present invention.

For example, the adhesive is not limited to the active silver solder, and any adhesive may be used as long as it has conductivity and can bond the cylindrical ceramic and the terminal electrode or the cap electrode and the terminal electrode.

The conductive coating may be Ag (silver), Ag (silver)/Pd (palladium) alloy, SnO₂(tin oxide), Al (aluminum), Ni (nickel), Cu (copper), Ti (titanium), Ta (tantalum), W (tungsten), SiC (silicon carbide), BaAl, C (carbon), Ag (silver)/Pt (platinum) alloy, TiO (titanium carbide), titanium dioxide, and the like₂Titanium oxide, TiC (titanium carbide), TiCN (titanium carbonitride), and the like.

The terminal electrode may be made of Cu (copper) or Ni (nickel) alloy, or kovar (registered trademark) alloy, which is an alloy of Fe (iron), Ni (nickel), and Co (cobalt), for example, may be used.

The metalized layers on the two end faces of the cylindrical ceramic can be Ag (silver), Cu (copper), Au (gold) and the like.

Further, the composition of the sealing gas is adjusted to obtain desired electrical characteristics, and may be, for example, atmospheric air (air), Ar (argon), N (argon), or the like₂(Nitrogen), Ne (Neon), He (helium), Xe (xenon), H₂(hydrogen), SF₆、CF₄、C₂F₆、C₃F₈、CO₂(carbon dioxide) and mixed gases thereof.

Claims (17)

1. A surge absorber, wherein: an insulating member formed by dividing the conductive film by a discharge gap; a pair of plate-like terminal electrodes disposed to face the insulating member; and an insulating tube having both ends provided with the pair of plate-like terminal electrodes and having the insulating member sealed therein together with a sealing gas,

a conductive member is provided at least between the conductive film and the plate-like terminal electrode.

2. The surge absorber of claim 1, wherein there is provided: a columnar insulating member formed by dividing the conductive coating on a peripheral surface thereof with the discharge gap; a pair of the plate-like terminal electrodes facing the conductive coating film at both ends of the insulating member; and the insulating tube for sealing the insulating member and the sealing gas inside,

and a conductive filler which is a conductive member and fills a gap between the conductive film and the plate-like terminal electrode.

3. The surge absorber of claim 1, wherein there is provided: a columnar insulating member formed by dividing the conductive coating on a peripheral surface thereof with the discharge gap; a pair of the plate-like terminal electrodes facing the conductive coating film at both ends of the insulating member; and the insulating tube for sealing the insulating member and the sealing gas inside,

a metal member is provided between the conductive film and the plate-like terminal electrode, and a conductive filler is contained as the conductive member to fill a gap between the metal member and the plate-like terminal electrode.

4. A surge absorber according to claim 2 or 3, wherein: and a holding member formed inside the insulating tube from the plate-like terminal electrode and projecting in an axial direction, for holding the insulating member.

5. A surge absorber according to claim 2 or 3, wherein: the pressure of the sealing gas is negative pressure.

6. The surge absorber of claim 1, wherein there is provided: a columnar insulating member formed by dividing the conductive coating on a peripheral surface thereof with the discharge gap; a pair of the plate-like terminal electrodes facing the conductive coating film at both ends of the insulating member; and the insulating tube, which is disposed at both ends of the pair of plate-like terminal electrodes by welding with a solder and seals the insulating member inside together with the sealing gas,

the plate-like terminal electrode and the conductive coating are bonded with an adhesive that is conductive to the conductive member.

7. The surge absorber of claim 1, wherein there is provided: a columnar insulating member formed by dividing the conductive coating on a peripheral surface thereof with the discharge gap; a pair of the plate-like terminal electrodes facing the conductive coating film at both ends of the insulating member; the insulating tube having the pair of plate-like terminal electrodes arranged at both ends thereof and sealed therein together with the sealing gas by welding with a solder,

a metal member is provided between the conductive film and the plate-like terminal electrode, and the metal member and the plate-like terminal electrode are bonded together with an adhesive that is conductive of the conductive member.

8. The surge absorber of claim 6 or 7, wherein: the solder and the adhesive are formed of different materials.

9. A surge absorber according to claim 6 or 7, wherein: and a holding member formed inside the insulating tube from the plate-like terminal electrode and projecting in an axial direction, for holding the insulating member.

10. The surge absorber of claim 9, wherein: the holding member is formed of the same material as the solder and different from the adhesive.

11. The surge absorber of claim 9, wherein: the holding member is formed of the same material as the adhesive and different from the solder.

12. The surge absorber of claim 9, wherein: the holding member is formed of a material different from the adhesive and the solder.

13. The surge absorber of claim 6 or 7, wherein: the pressure of the sealing gas is negative pressure.

14. The surge absorber of claim 1, wherein there is provided: a columnar or plate-shaped insulating member formed by dividing the conductive coating by the discharge gap on a peripheral surface; a pair of the plate-like terminal electrodes facing the conductive coating film at both ends of the insulating member; the insulating tube having the pair of plate-like terminal electrodes disposed at both ends thereof and sealing the insulating member inside together with the sealing gas,

a conductive buffer member is provided between the conductive film and the plate-like terminal electrode as the conductive member.

15. The surge absorber of claim 14, wherein: the buffer member is any one of a metal plate or a metal foil, a foamed metal, a fiber metal, or a solder.

16. The surge absorber of claim 14, wherein: the buffer member is provided with a raised portion for holding the outer peripheral surfaces of both ends of the insulating member.

17. A method of manufacturing a surge absorber having the structure of claim 14, wherein: the buffer member is provided between the end surface of the conductive film inserted into the insulating tube and the plate-shaped terminal electrode, and the plate-shaped terminal electrode is bonded to both ends of the insulating tube to seal the insulating tube.