JP2020161271A - Manufacturing method of surge protective element - Google Patents

Abstract

To provide a manufacturing method of a surge protective element, which can produce an extremely narrow gap in a low cost.SOLUTION: A manufacturing method of a surge protective element, includes: a fuse member attachment step of connecting a pair of sealing electrodes with a fuse member by fixing both ends of a fuse member 4 to an opposite surface of both of the pair of sealing electrodes 3; an electrode insertion step of inserting the pair of sealing electrodes into an insulation pipe 2 in a state where a tensile force is applied to the fuse member in the pair of sealing electrodes connected with the fuse member; an electrode jointing step of blocking both end open parts of the insulation pipe with the pair of sealing electrodes in the state where it is connected with the fuse member to seal a discharge control gas in an inner part, and jointing the insulation pipe and the pair of sealing electrodes; and a fuse member fusing step of fusing the fuse member by heating the fuse member after the electrode jointing step.SELECTED DRAWING: Figure 1

Description

The present invention relates to a method for manufacturing a surge protective element used to protect various devices from a surge generated by a lightning strike or the like and prevent an accident.

Abnormal voltage such as lightning surge and static electricity in parts where electronic devices for communication devices such as telephones, facsimiles and modems connect to communication lines, power lines, antennas or CRTs, image display drive circuits such as LCD TVs and plasma TVs, etc. A surge protective element is connected to a portion susceptible to electric shock due to (surge voltage) in order to prevent thermal damage or ignition of an electronic device or a printed substrate on which the device is mounted due to an abnormal voltage.

Conventionally, for example, Patent Document 1 describes a microgap type surge protective element in which a conductively coated member is sandwiched between opposing metal members in a glass tube. This microgap type surge protection element has a structure in which a slit (gap) of several μm to several tens of μm is provided in the center of the conductively coated member so that current does not flow between the opposing metal members below a specified voltage. .. When the voltage exceeds the set voltage, an arc discharge is generated between the slits, and a current flows between the opposing metal members.

This surge protection element is a device that utilizes the shape-changing ability of a glass tube due to glass softening and the bonding characteristics with a metal, and is used in a wide range of fields because of its excellent mass productivity.
Further, Patent Document 2 includes surge protection provided with a cylindrical body made of ceramics, glass, or the like and a pair of electrodes facing each other with a space of a predetermined distance interposed therebetween by interposing an electrically insulating ring-shaped spacer. The elements are described. Like such a surge protective element, a surge protective element in which the counter electrode is sealed with a ceramic cylinder such as alumina is called an arrester.

Special Publication No. 63-57918 Japanese Unexamined Patent Publication No. 63-318805

The following problems remain in the above-mentioned conventional technique.
That is, the glass-coated microgap type surge protection element has good bondability between glass and a metal member, and has excellent reliability such as gas sealing property and air and moisture blocking property. However, since the width of the slit forming the microgap is narrow and the thickness of the conductive coating forming the periphery of the microgap is as thin as several tens of μm, the surge resistance is limited to about 1500 A. In addition, a film forming process for the conductive coating and a laser processing process for forming a microgap are required, which has the disadvantage that the process becomes complicated, the production takes time, and the cost increases.

On the other hand, the arrester type surge protective element has a withstand capacity of 2000 A in a product having a diameter of 5 mm and a withstand capacity of 5000 A in a product having a diameter of 8 mm, and has a surge tolerance characteristic higher than that of a glass-coated microgap type surge protective element. There is. Such arrester-type surge protective elements are used for large household appliances, solar power generation, water and sewage, and other infrastructure equipment that require high reliability. The arrester-type surge protective element requires an expensive bonding agent (silver brazing material) or an alumina cylindrical member, which is more expensive than the glass cylindrical member, in joining the metal and the ceramics. Furthermore, very high technology is required for joining ceramics and metal parts, and an electrode auxiliary material (graphite, etc.) is provided inside the electrode, and a dielectric material is used on the surface of the counter electrode for the purpose of protecting the electrode and promoting discharge. It is necessary to give it, which complicates the manufacturing process. Therefore, the manufacturing cost tends to increase significantly as compared with the glass-coated microgap type surge protective element. In particular, when used as a countermeasure against static electricity, it is necessary to separate the opposing electrodes at very narrow intervals such as the above-mentioned micro gap, and it is difficult to set the gap with high accuracy.
Further, there is a problem that the metal constituting the electrode portion is melted and scattered by the arc discharge, and the metal component adheres to the inner surface of the insulating tube, which deteriorates the insulating property between the pair of sealing electrodes. In particular, if a large amount of metal component adheres to the inner surface of the insulating tube, an energizing circuit may be formed on the inner surface of the insulating tube, resulting in a short circuit. In that case, it is judged that the life of the surge protective element has expired. There was an inconvenience. In the surge protection element described in Patent Document 2, since the ring-shaped spacer is interposed, the metal component does not adhere to the inner peripheral surface of the insulating tube, but the metal component adheres to the inner peripheral surface of the ring-shaped spacer. Then, there was a risk of a short circuit. In addition, a ring-shaped spacer must be manufactured as a separate member and installed between the sealing electrodes, making it difficult to obtain a very narrow gap.

The present invention has been made in view of the above-mentioned problems, and an object of the present invention is to provide a method for manufacturing a surge protective element capable of producing a very narrow gap at low cost.

The present invention has adopted the following configuration in order to solve the above problems. That is, the surge protection element according to the first invention includes a fuse member mounting step of fixing both ends of the fuse member to the facing surfaces of the pair of sealing electrodes and connecting the pair of sealing electrodes with the fuse member. An electrode insertion step of inserting the pair of sealing electrodes connected by the fuse member into an insulating tube with tension applied to the fuse member, and a state of being connected by the fuse member. An electrode joining step of closing both ends of the insulating tube with the pair of sealing electrodes to seal the discharge control gas inside and joining the insulating tube and the pair of sealing electrodes, and the above-mentioned. It is characterized by having a fuse member blowing step of heating the fuse member after the electrode joining step to blow the fuse member.

This method of manufacturing a surge protective element includes a fuse member blowing step of heating the fuse member after the electrode joining step to blow the fuse member. Therefore, after fixing the sealing electrode, the fuse member is blown to form a pair of seals. The electrodes can be completely separated to form a gap, and the distance between the pair of sealing electrodes can be easily and highly accurately set according to the length of the fuse member.

In the surge protection element according to the second invention, in the first invention, the fuse member is formed of a conductive material, and the fuse member blowing step causes a current to flow between the pair of sealing electrodes to cause the fuse. The member is blown by resistance heating by the electric current.
That is, in this method of manufacturing a surge protective element, in the fuse member blowing step, a current is passed between a pair of sealing electrodes to blow the fuse member by resistance heating by the current, so that the material of the fuse member and the current value are set. This makes it possible to easily blow the fuse member. Therefore, it is possible to heat only the fuse portion, and it is possible to suppress the influence on the insulating tube as compared with the method of irradiating a laser beam or the like from the outside to heat the fuse portion.

The surge protective element according to the third invention is characterized in that, in the first or second invention, a recess is formed in at least one of the facing surfaces of the pair of sealing electrodes.
That is, in this method of manufacturing a surge protective element, a recess is formed in at least one of the facing surfaces of the pair of sealing electrodes, so that the blown fuse member enters the recess to flatten the facing surface. It becomes easy and stable surge characteristics can be obtained.

In the surge protective element according to the fourth invention, in any one of the first to third inventions, the fuse member contains an ion source material having a higher electron emitting ability than the material of the sealing electrode. It is characterized by.
That is, in this method of manufacturing the surge protection element, since the fuse member contains an ion source material having a higher electron discharging ability than the material of the sealing electrode, the conductive particles of the ion source material in the fuse member are used. The melted fuse member (molten body) itself has a discharge assist function as a trigger for arc discharge.

According to the present invention, the following effects are obtained.
That is, according to the method for manufacturing a surge protective element according to the present invention, since the fuse member has a fuse member blowing step of heating the fuse member to blow the fuse member, the distance between the pair of sealing electrodes is easily and high. The distance between the pair of sealing electrodes can be easily and highly accurately set according to the length of the fuse member.
Therefore, the surge protection element according to the present invention is suitable for a power supply circuit section or a communication circuit section of an electric device that requires a compact, inexpensive, and highly reliable product. In particular, the surge protection element of the present invention is suitable for a wide range of applications including measures against static electricity for mounting on a substrate.

It is sectional drawing in the axial direction which shows the surge protection element before the fuse member blowing process in 1st Embodiment of the manufacturing method of the surge protection element which concerns on this invention. In the first embodiment, it is an exploded perspective view which shows the surge protection element before the fuse member blowing process. In the first embodiment, it is sectional drawing in the axial direction which shows the surge protection element which the molten fuse member (molten body) adhered to both facing surfaces of a pair of sealing electrodes. It is sectional drawing in the axial direction which shows the surge protection element before the fuse member blowing process in 2nd Embodiment of the manufacturing method of the surge protection element which concerns on this invention. It is a perspective view which shows the sealing electrode in 2nd Embodiment. In the second embodiment, it is sectional drawing in the axial direction which shows the surge protection element which the molten fuse member (molten body) adhered to both facing surfaces of a pair of sealing electrodes.

Hereinafter, the first embodiment of the method for manufacturing a surge protective element according to the present invention will be described with reference to FIGS. 1 to 3. In each drawing used in the following description, the scale is appropriately changed in order to make each member recognizable or easily recognizable.

As shown in FIG. 3, the surge protection element 1 of the present embodiment is a pair of sealing electrodes 3 that close the insulating tube 2 and the openings at both ends of the insulating tube 2 to seal the discharge control gas inside. And have.
A melt 14 of a fuse member 4, which will be described later, is attached to at least one of the facing surfaces of the pair of sealing electrodes 3.
In the surge protection element 1 of the present embodiment, as shown in FIG. 3, the molten body 14 is attached to both of the facing surfaces of the pair of sealing electrodes 3, but the facing surfaces of the pair of sealing electrodes 3 The melt 14 may adhere to only one of them.

The insulating tube 2 is, for example, cylindrical and is made of a glass tube such as lead glass. The insulating tube 2 is preferably formed of a glass tube that is inexpensive and has excellent sealing properties, but may be formed of a crystalline ceramic material such as alumina.
The discharge control gas sealed in the insulating tube 2 is an inert gas or the like, for example, He, Ar, Ne, Xe, Kr, SF ₆ , CO ₂ , C ₃ F ₈ , C ₂ F ₆ , CF ₄ , H ₂ , air, etc. and a mixed gas thereof are adopted.

The sealing electrode 3 is formed in a columnar shape with, for example, a jumet wire, 42 alloy (Fe: 58 wt%, Ni: 42 wt%), Cu or the like.
In this embodiment, the pair of sealing electrodes 3 enter the inside of the insulating tube 2 to close the openings at both ends.
A base end portion of a lead wire 5 projecting outward is embedded in each sealing electrode 3.
The melt 14 is a conductive material such as a Ni-based, Fe-based, or Cu-based alloy.

In the method of manufacturing the surge protection element 1 of the present embodiment, as shown in FIGS. 1 and 2, both ends of the fuse member 4 are fixed to the facing surfaces of the pair of sealing electrodes 3 and the fuse members 4 form a pair. A fuse member mounting step for connecting the sealing electrodes 3, a pair of sealing electrodes 3 connected by the fuse member 4, a pair of sealing electrodes 3 in a state where tension is applied to the fuse member 4, and an electrode insertion step for the fuse member. The openings at both ends of the insulating tube 2 are closed by the pair of sealing electrodes 3 connected by 4, the discharge control gas is sealed inside, and the insulating tube 2 and the pair of sealing electrodes 3 are joined. As shown in FIG. 3, it has an electrode joining step and a fuse member blowing step of heating the fuse member 4 to blow the fuse member 4 after the electrode joining step.

The fuse member 4 is made of a conductive material.
Further, in the fuse member blowing step, a current is passed between the pair of sealing electrodes 3 to blow the fuse member 4 by resistance heating by the current.

In the fuse member mounting step, the fuse member 4 has a linear or block shape, and the end portion is adhered to the facing surface of the sealing electrode 3 by welding or the like. In this embodiment, the wire-shaped fuse member 4 is adopted.
In the electrode insertion step, for example, one of the pair of sealing electrodes 3 is placed upward and the other is suspended, and tension is applied to the fuse member 4 to insert the fuse member 3 into the insulating tube 2.
In this case, the lower sealing electrode 3 is suspended from the upper sealing electrode 3 via the fuse member 4, and after sealing, a current is applied to the pair of lead wires 5 and the sealing electrode 3 to apply the current to the fuse member. 4 is fused and flowed by Joule heat.

The fuse member 4 is preferably made of a material having a temperature higher than the bonding temperature between the insulating tube 2 and the sealing electrode 3 by 50 ° C. or more, and Ni-based, Fe-based, Cu-based alloys and the like can be used. It should be noted that Zn and Sn alone have a low melting point and are not suitable as the fuse member 4.
Further, in order to adjust the breaking current of the fuse member 4, an alloy may be obtained by adding Bi, Ag, Sb, In or the like to the material of the fuse member 4.
When the fuse member 4 is heated by Joule heat and melted, it spreads like a film on the facing surface of the sealing electrode 3, and after the heating is completed, it cools and solidifies to become the molten body 14.

As described above, the method for manufacturing the surge protection element 1 of the present embodiment includes a fuse member blowing step of heating the fuse member 4 to blow the fuse member 4 after the electrode joining step, and therefore, after fixing the sealing electrode 3. The fuse member 4 can be blown to completely separate the pair of sealing electrodes 3 to form a gap, and the distance between the pair of sealing electrodes 3 can be easily and accurately adjusted according to the length of the fuse member 4. Can be set to.

Further, in the fuse member blowing step, a current is passed between the pair of sealing electrodes 3 to blow the fuse member 4 by resistance heating by the current, so that the fuse member 4 can be easily set by setting the material and the current value of the fuse member 4. Can be blown. Therefore, it is possible to heat only the fuse member 4, and it is possible to suppress the influence on the insulating tube 2 as compared with the method of irradiating and heating the fuse member 4 from the outside.

Next, a second embodiment of the method for manufacturing a surge protective element according to the present invention will be described below with reference to FIGS. 4 to 6. In the following description of the embodiment, the same components described in the above embodiment are designated by the same reference numerals, and the description thereof will be omitted.

The difference between the second embodiment and the first embodiment is that in the first embodiment, the facing surface of the sealing electrode 3 is flat, whereas in the method for manufacturing the surge protection element 21 of the second embodiment, the facing surface is flat. As shown in FIGS. 4 to 6, a recess 23a is formed on at least one of the facing surfaces of the pair of sealing electrodes 23.
In the second embodiment, the recesses 23a are formed in an annular shape on both of the facing surfaces of the pair of sealing electrodes 23.

Further, in the second embodiment, the fuse member 4 and the melt 14 contain an ion source material having a higher electron emitting ability than the material of the sealing electrode 23.
For example, the fuse member 4 and the melt 14 contain a material such as carbon powder having a higher electron emitting ability than the sealing electrode 23 as an ion source material.
The recess 23a is formed in a semicircular cross section, but may be a recess having a V-shaped cross section. Further, although one annular recess 23a is formed, a plurality of recesses 23a may be formed.

The fuse member 4 is installed in the center of the annular recess 23a, and when melted, the molten body 14 expands on the facing surface and easily enters the surrounding recess 23a. Further, the annular recess 23a can prevent the molten body 14 from spreading outward in the radial direction with respect to the recess 23a.

In the present embodiment, the recess 23a is formed on both facing surfaces of the pair of sealing electrodes 23, but the recess 23a may be formed only on one facing surface.
When holding the pair of sealing electrodes 23 horizontally at the time of joining, it is preferable to form recesses 23a on both facing surfaces of the pair of sealing electrodes 23.
Even when the pair of sealing electrodes 23 are held vertically, a recess 23a is also formed on the upper facing surface, and depending on the viscosity of the fuse member 4 and the size of the recess 23a, the surface tension of the melt 14 causes the upper facing surface. The molten body 14 can enter the recess 23a. Further, by forming the recesses 23a on both facing surfaces, the area of the molten body 14 covering one facing surface is reduced, and it is possible to further suppress the decrease in the discharge area and increase the amount of surge. become.

As described above, in the method of manufacturing the surge protection element 21 of the second embodiment, since the recess 23a is formed on at least one of the facing surfaces of the pair of sealing electrodes 23, the molten body 14 of the melted fuse member 4 is formed. By entering the recess 23a, the facing surface can be easily flattened, and stable surge characteristics can be obtained. Further, since the melt 14 enters the recess 23a and at least a part of the melt 14 is housed, the area of the melt 14 covering the facing surface can be reduced, and the decrease in the discharge area is suppressed to increase the amount of surge. Becomes possible.
Further, since the fuse member 4 contains an ion source material having a higher electron emission ability than the material of the sealing electrode 3, the molten body 14 can have a discharge assisting function as a trigger for arc discharge.

The technical scope of the present invention is not limited to each of the above embodiments, and various modifications can be made without departing from the spirit of the present invention.
For example, in the first embodiment, the melt 14 spreads like a film, but the melt 14 is impregnated into the sealing electrode 3 by making the pair of facing surfaces of the sealing electrodes 3 porous. You may let me. Further, the melt 14 spread in a film shape may be alloyed with the sealing electrode 3.

1,21 ... Surge protection element, 2 ... Insulating tube, 3,23 ... Sealing electrode, 4 ... Fuse member, 14 ... Melt, 23a ... Recess

Claims (4)

A fuse member mounting process in which both ends of the fuse member are fixed to the facing surfaces of the pair of sealing electrodes and the pair of sealing electrodes are connected by the fuse member.
An electrode insertion step of inserting the pair of sealing electrodes connected by the fuse member into an insulating tube with tension applied to the fuse member.
The pair of sealing electrodes connected by the fuse member closes the openings at both ends of the insulating tube to seal the discharge control gas inside, and the insulating tube and the pair of sealing electrodes are connected to each other. The electrode joining process to join and
A method for manufacturing a surge protective element, which comprises a fuse member blowing step of heating the fuse member after the electrode joining step to blow the fuse member. In the method for manufacturing a surge protective element according to claim 1,
The fuse member is made of a conductive material and
A method for manufacturing a surge protective element, wherein the fuse member blowing step causes a current to flow between the pair of sealing electrodes to blow the fuse member by resistance heating by the current. In the method for manufacturing a surge protective element according to claim 1 or 2.
A method for manufacturing a surge protective element, characterized in that a recess is formed on at least one of the facing surfaces of the pair of sealing electrodes. In the method for manufacturing a surge protective element according to any one of claims 1 to 3,
A method for manufacturing a surge protective element, wherein the fuse member contains an ion source material having a higher electron emitting ability than the material of the sealing electrode.

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