JP2004127615A - Surge absorber and manufacturing method of same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a surge absorber which can be easily miniaturized, and manufacturing method of the same capable of manufacturing the surge absorber in large quantity at a time. <P>SOLUTION: A lamination body 25 is formed by a plurality of laminated insulation materials 23. A discharging space 29 is formed inside the laminate 25 by forming a hole 27 or a concave part between the insulation materials 23 constructing the laminate 25. A pair of discharging electrodes 31 are arranged at the same insulation material 23 in which the hole 27 or the concave part is formed, and the pair of the discharging electrodes 31 are made to face each other in the discharging space 29. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a surge absorber that absorbs a surge voltage and a method of manufacturing the same, and more particularly, to an improved technique that enables downsizing.
[0002]
[Prior art]
Chip-type surge absorbers are connected to parts where electronic devices such as telephones and modems are connected to communication lines, or to parts that are susceptible to electric shock such as lightning surges or static electricity, such as CRT drive circuits. Is used to prevent destruction.
[0003]
As shown in FIG. 6, a conventional chip-type surge absorber 1 has discharge electrodes 5 and 7 formed on a plate surface of an insulating substrate 3 made of an insulating material such as alumina so that the discharge electrodes 5 and 7 are opposed to each other. A discharge gap 9 called a microgap is provided between the two (see, for example, Patent Document 1 described later). The discharge electrode 5 and the discharge electrode 7 can be formed as an integrated print pattern facing each other across the discharge gap 9 by screen-printing the electrode material.
[0004]
Above these discharge electrodes 5 and 7, a box-shaped ceramic lid 13 is attached on the insulating substrate 3 so as to form the internal space 11. Gas atmosphere. The lid 13 is covered with an adhesive 15 applied around the insulating substrate 3 so that the outer ends of the discharge electrodes 5 and 7 protrude outside. Terminal electrodes 17 and 19 are formed on both ends of the lid 13 and the insulating substrate 3 by plating or the like, and the terminal electrodes 17 and 19 are connected to the respective discharge electrodes 5 and 7.
[0005]
[Patent Document 1]
JP-A-2002-15832 (paragraph 0003, FIG. 3)
[0006]
In the surge absorber 1 having such a configuration, when a large surge voltage exceeding the discharge starting voltage flows through the discharge electrodes 5 and 7, the glow discharge a is triggered through the discharge gap 9 between the distal ends of the discharge electrodes 5 and 7. Then, as shown by the arrow b, this discharge gradually extends in the internal space 11 in the form of a creeping discharge to the outer end sides of the two discharge electrodes 5 and 7, and further, as shown in c, the discharge electrodes 5 and 7 An arc discharge occurs between the outer ends, thereby absorbing a surge voltage generated between the circuits.
[0007]
[Problems to be solved by the invention]
However, the conventional surge absorber described above has a difficulty in downsizing because it covers the box-shaped lid to form an internal space. Moreover, since the lids are attached to the insulating substrate on which the discharge electrodes are formed while positioning the lids one by one in an inert gas and assembling them, a large amount of sealing cannot be performed at once.
SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a surge absorber and a method of manufacturing the surge absorber, which can be easily reduced in size, and can easily obtain a large amount of surge absorbers at once.
[0008]
[Means for Solving the Problems]
According to the first aspect of the present invention, there is provided a surge absorber, wherein a laminated body is formed from a plurality of laminated insulating materials, and the inside of the laminated body is formed by holes or recesses provided in the insulating material. And a pair of discharge electrodes formed on the same insulating material face each other in the discharge space.
[0009]
In this surge absorber, the discharge space is formed in the laminated body of the insulating material, and it is not necessary to cover the box-shaped lid to form the internal space unlike the conventional structure. In addition, since a pair of discharge electrodes are formed on the same insulating material, the discharge space is sealed by laminating at least two insulating materials, particularly in the case where the discharge space is formed by concave portions, and an extremely thin surge absorber is formed. It can be manufactured. Furthermore, since the pair of discharge electrodes face each other via the discharge space formed by the hole, by changing the shape and size of the hole, the discharge electrodes face each other while maintaining a constant lamination thickness (thinness). The distance can be set freely.
[0010]
The surge absorber according to claim 2 is the surge absorber according to claim 1, wherein the plurality of insulating materials on which the pair of discharge electrodes are formed are stacked to form a pair of discharge electrodes facing each other in the discharge space. , A plurality of pairs are provided.
[0011]
In this surge absorber, when the discharge electrode that has been discharged first cannot be discharged due to long-term use, the discharge moves to the discharge electrode that is easily discharged next, and the discharge start voltage is kept low for a long time. Continue to be.
[0012]
A method for manufacturing a surge absorber according to claim 3, wherein a band-shaped first discharge electrode whose base end reaches one end surface of the sheet and whose front end reaches the center of the sheet is formed on at least one ceramic green sheet; Forming a band-shaped second discharge electrode leading to the end surface and reaching the center of the sheet, forming a hole or recess for cutting the first discharge electrode and the second discharge electrode in the center of the ceramic green sheet, Another ceramic green sheet is laminated on and under the ceramic green sheet and pressed, and the pressed plurality of ceramic green sheets are integrally fired.
[0013]
In this method for manufacturing a surge absorber, a plurality of holes and a discharge electrode are arranged at predetermined positions, and a ceramic green sheet is laminated, so that a pair of discharge electrodes can be simultaneously opposed to each discharge space, and a large number of surge absorbers can be disposed. Can be manufactured easily and all at once.
[0014]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, preferred embodiments of a surge absorber and a method of manufacturing the surge absorber according to the present invention will be described in detail with reference to the drawings.
FIG. 1 is a longitudinal sectional view of a surge absorber according to the present invention, FIG. 2 is a view along arrow AA in FIG. 1, FIG. 3 is a view along arrow BB in FIG. 2, and FIG. 4 is a surge absorber shown in FIG. FIG. 5 is an enlarged view of a main part showing a modified example of the surge absorber shown in FIG.
[0015]
In the surge absorber 21 according to the present embodiment, a plurality of insulating materials 23 are stacked to form a stacked body 25. In the laminate 25, a discharge space 29 sealed inside is formed by a hole 27 or a recess formed in the insulating material 23. As shown in FIG. 2, an arbitrary one of the plurality of insulating materials 23 constituting the laminate 25 includes a first discharge electrode 31 a and a second discharge electrode 31 b which are a pair of discharge electrodes 31. Is formed.
[0016]
The first and second discharge electrodes 31a and 31b are arranged in parallel. Then, the first discharge electrode 31a is formed in a band shape in which the base end 33 reaches one end face (the right end face in FIG. 2) of the insulating material 23 and the tip end 35 reaches the center of the insulating material 23. The second discharge electrode 31b is formed in a strip shape in which the base end 33 reaches the other end surface (the left end surface in FIG. 2) of the insulating material 23 and the front end 35 reaches the center of the insulating material 23.
[0017]
The hole 27 is formed in the center of the insulating member 23, and the hole 27 cuts the first and second discharge electrodes 31a and 31b in an arc shape. Therefore, as shown in FIG. 3, the pair of first and second discharge electrodes 31 a and 31 b formed on the same insulating material 23 face each other in the discharge space 29. The discharge space 29 is filled with an inert gas as needed.
[0018]
In FIG. 1, 32a and 32b represent terminal electrodes connected to the first and second discharge electrodes 31a and 31b exposed on the end face of the laminate 25.
[0019]
Here, the laminated structure of the laminated body 25 in which the discharge space 29 is formed will be described in more detail.
In order to form the sealed discharge space 29, for example, a laminated structure shown in FIG. 4 can be used. That is, the first and second discharge electrodes 31a and 31b are formed on the upper surface of the insulating material 23a. A hole 27 is formed in the insulating material 23a. This insulating material 23a is laminated by being sandwiched from above and below by a pair of insulating materials 23b and 23c in which a hole 27 is formed. Further, the laminated body 25 is obtained by sandwiching the insulating members 23d and 23e in which the holes 27 are not formed. According to the laminated body 25, the first and second discharge electrodes 31a and 31b can be positioned at the center in the discharge space axis direction by the interposition of the insulating materials 23b and 23c.
[0020]
Further, the laminated structure may be configured such that the insulating material 23b and the insulating material 23c shown in FIG. 4 are omitted. In this case, the laminate 25 can be manufactured using three insulating materials 23a, 23d, and 23e, which are two less than the above-described configuration.
[0021]
Further, the laminated structure is also constructed by omitting the insulating material 23b, the insulating material 23c, and the insulating material 23e shown in FIG. 4 and forming a concave portion (not shown) instead of the hole 27 formed in the insulating material 23a. be able to. In this case, the discharge space 29 is sealed by the bottom surface of the recess formed in the insulating material 23a and the lower surface of the insulating material 23d. According to this laminated structure, the laminated body 25 can be manufactured from the two insulating members 23a and 23d, and the thickness can be easily reduced significantly as compared with the surge absorber having the conventional structure.
[0022]
Note that the first and second discharge electrodes 31a and 31b are desirably cut out by the holes 27 or recesses. As a result, the pair of first and second discharge electrodes 31a and 31b face each other via the discharge space 29, and a constant lamination thickness is maintained by changing the shape and size of the hole 27 or the concave portion. The facing distance between the first and second discharge electrodes 31a and 31b can be freely set.
[0023]
Further, in the present embodiment, the relative positions of the pair of first and second discharge electrodes 31a and 31b will be described as an example where they are formed on the same plane in parallel. , 31b may be arranged linearly on the same plane, and may be separated by the hole 27 or the concave portion.
[0024]
According to the surge absorber 21, the discharge space 29 is formed in the laminated body 25 of the insulating material 23, and it is not necessary to cover the box-shaped lid to form the internal space unlike the conventional structure. In addition, since a pair of discharge electrodes 31 are formed on the same insulating material 23, especially when the discharge space 29 is formed by a concave portion, a surge absorber in which the discharge space 29 is sealed by stacking at least two insulating materials 23 is provided. 21 can be formed, and an extremely thin surge absorber 21 can be easily manufactured. Further, a pair of discharge electrodes 31 are opposed to each other via a discharge space 29 formed by the hole 27, and by changing the shape and size of the hole 27, the discharge electrode 31 is maintained while maintaining a constant lamination thickness (thinness). The opposing distance between them can be freely set.
[0025]
In the above embodiment, the case where the first and second discharge electrodes 31a and 31b are formed on one insulating material 23 has been described as an example. However, the surge absorber according to the present invention has a structure as shown in FIG. The first and second discharge electrodes 31a and 31b are formed on each of a plurality of insulating materials 23 (three in the illustrated example), and a plurality of pairs of discharge electrodes (3 in the illustrated example) facing each other in the discharge space 29 are formed. Pair) may be provided. With such a configuration, when the first and second discharge electrodes 31a and 31b (for example, those of the middle layer) which have been discharged first cannot be discharged due to long-term use, the first discharge electrode 31a and 31b which is easily discharged next is used. The discharge can be transferred to the second discharge electrodes 31a and 31b (for example, the upper layer), and the discharge start voltage can be kept low.
[0026]
Next, a method of manufacturing the surge absorber 21 configured as described above will be described. First, for example, a material obtained by adding a sintering aid to a powder of an insulating material such as alumina (Al ₂ O ₃ ) such as corundum, mullite, corundum mullite, etc., is processed into a sheet having a thickness of 1 μm to 200 μm to obtain a ceramic. A green sheet (a material before sintering the insulating material 23) is prepared. Here, as sintering aids, SiO ₂ (silicon dioxide), B ₂ O ₃ (boron oxide), PbO (lead oxide), Na ₂ O (disodium oxide), Li ₂ O (lithium oxide), BaO (Barium oxide), CaO (calcium oxide), ZnO (zinc oxide), MgO (magnesium oxide), TiO ₂ (titanium oxide), or a mixture of two or more of Al ₂ O ₃ is used. be able to.
[0027]
Subsequently, strip-shaped first and second discharge electrodes 31a and 31b are formed on at least one ceramic green sheet, with one end (base end 33) reaching the sheet end face and the other end (tip end 35) reaching the sheet center. Form. The discharge electrodes 31a and 31b are formed in a strip shape having a width of, for example, 0.01 mm to 0.30 mm and a length of 0.6 mm to 1.5 mm. (Interval) is about 0.01 mm to 0.30 mm.
The discharge electrodes 31a and 31b are made of, for example, RuO ₂ (ruthenium oxide) -glass, Ag / Pd (silver / palladium), SnO ₂ (tin dioxide), Al (aluminum), Ni (nickel), Cu ( Copper), Ti (titanium), TiN (titanium nitride), Ta (tantalum), W (tungsten), SiC (silicon carbide), BaAl (barium aluminum), Nb (niobium), Si (silicon), C (carbon) , Ag (silver), Ag / Pt (silver / platinum), ITO (indium-tin oxide) and the like. The discharge electrodes 31a and 31b may be formed by, for example, screen printing, or may be formed by a sputtering method, a CVD method, an ion plating method, a printing method, or a vapor deposition method.
[0028]
Next, a hole 27 is formed in the center of the ceramic green sheet (corresponding to the insulating material 23a in FIG. 4) to cut the discharge electrodes 31a and 31b. The hole 27 has a diameter of, for example, 0.1 mm to 0.7 mm, and its cross-sectional shape may be a perfect circle, an ellipse, or a polygon such as a triangle or more.
Next, another ceramic green sheet (corresponding to the insulating materials 23d and 23e in FIG. 4) is laminated and pressed on the upper and lower sides of the ceramic green sheet. In this pressure bonding step, a pressure of 98.1 MPa to 490.3 MPa is applied to the ceramic green sheets 23 a, 23 d, and 23 e while being heated to 50 ° C. to 90 ° C. to perform pressure bonding.
[0029]
Finally, the plurality of pressed ceramic green sheets are heated to 600 ° C. to 1100 ° C. in an inert gas (atmospheric pressure of 13330 Pa to 133300 Pa) using a tunnel furnace, a batch furnace, or the like for 1 minute to By holding for 3 hours, it is integrally fired. Here, the inert gas used in the firing is He (helium), Ar (argon), Ne (neon), Xe (xenon), SF ₆ (sulfur hexafluoride), CO ₂ (carbon dioxide), C ₃ F ₈ (perfluoropropane), C ₂ F ₆ (perfluoroethane), CF ₄ (tetrafluoromethane), H ₂ (hydrogen molecular gas), atmosphere, and a mixed gas thereof can be used.
Thereafter, a conductive paste such as an Ag (silver) conductive paste is applied to both sides of the sintered body on which the first and second discharge electrodes 31a and 31b are exposed, and baked at, for example, 600 ° C. 32a and 32b are formed.
Here, the terminal electrodes 32a and 32b may be manufactured using a conductive resin paste. The firing temperature in this case is set to 120 ° C to 250 ° C.
[0030]
According to the method of manufacturing the surge absorber 21, the ceramic green sheets in which the plurality of holes 27 and the discharge electrodes 31 are arranged at predetermined positions are stacked, so that a pair of discharge electrodes 31 are simultaneously arranged in each discharge space 29 so as to face each other. This makes it possible to manufacture a large number of surge absorbers 21 easily and at once.
Further, according to the method of manufacturing the surge absorber 21, since it is not necessary to form a micro gap by using a laser or the like, the number of steps can be reduced and the manufacturing cost can be reduced.
[0031]
【Example】
Step 1.
First, a powder of Al ₂ O _{3 and} a powder of SiO ₂ are weighed so as to have a weight ratio of 4: 6, and an organic binder, a solvent, a dispersant, and a plasticizer are added thereto, and mixed with a ball mill for 24 hours. Then, a slurry was prepared, and this slurry was processed into a single-layer ceramic green sheet having a thickness of 50 μm by a doctor blade method.
Eight single-layer ceramic green sheets were stacked, and a pressure of 196 MPa was applied thereto while being heated to a temperature of 70 ° C., and they were pressed together to form a single stacked sheet. A total of two such stacked sheets were produced. . These laminated sheets constitute the insulator layers that form the upper and lower surfaces of the surge absorber.
[0032]
Step 2.
Next, the three ceramic green sheets having a thickness of 50 μm are laminated and pressed to form one laminated sheet, and on one surface thereof, a RuO ₂ -glass paste is printed and dried in a region forming each surge absorber. In each region, one discharge electrode extending from one edge to the center of the region and the other discharge electrode extending parallel to the one discharge electrode and facing the one edge from the edge to the center of the region were formed. Here, these discharge electrodes were formed in a band shape having a width of 0.15 mm, a length of 1.00 mm, and a thickness of 5 μm, and their interval (interval in the width direction) was 0.20 mm.
Then, three ceramic green sheets each having a thickness of 50 μm are further laminated on the surface of the laminated sheet on which the discharge electrodes are to be formed, and these are pressed under pressure of 196 MPa while being heated to a temperature of 70 ° C. One laminated sheet was obtained.
Further, a hole (via hole portion) having a diameter of 0.3 mm was formed by punching in the center of each surge absorber in the laminated sheet, and the end face of each discharge electrode was exposed in the hole.
[0033]
Step 3.
One of the laminated sheets formed in step 1 is laminated and pressed on one surface of the laminated sheet formed in step 2, and the via holes of the laminated sheet formed in step 2 are inserted into an organic vehicle (organic binder and solvent). After that, another laminated sheet formed in the step 1 was laminated on the other surface of the laminated sheet formed in the step 2 and pressed. Here, these laminated sheets were pressure-bonded by applying a pressure of 196 MPa while heating to a temperature of 70 ° C.
[0034]
Step 4.
Thereafter, the laminated body of the laminated sheet is cut into regions forming respective surge absorbers to form chip-shaped laminated bodies, and these chip-shaped laminated bodies are heated in the air to be degreased, and then inert gas (Ar, It was heated to 900 ° C. in an atmosphere pressure of 106656 Pa) and held for 2 hours for firing.
The chip-shaped sintered body thus obtained is subjected to barrel polishing to remove corners, and then an Ag conductive paste is applied to the surface of the sintered body where the electrodes are exposed, and fired at 600 ° C. in the air. Then, a terminal electrode was formed.
Furthermore, by applying Ni plating and solder plating to the terminal electrodes, a small chip type surge absorber of 1.6 mm × 0.8 mm × 0.8 mm could be manufactured.
[0035]
【The invention's effect】
As described in detail above, according to the surge absorber according to claim 1 of the present invention, a plurality of insulating materials are laminated to form a laminated body, and a hole or a concave portion is provided in the insulating material to form the inside of the laminated body. Since a pair of discharge electrodes formed on the same insulating material are opposed to each other in this discharge space, a discharge space can be formed in a laminate of insulating materials, as in the conventional structure. There is no need to form an internal space by attaching a box-shaped lid, and the size can be easily reduced. In addition, since a pair of discharge electrodes are formed on the same insulating material, a surge absorber can be constructed by laminating at least two insulating materials, especially in the case where the discharge space is formed by a recess, which is significantly larger than the surge absorber of the conventional structure. It is possible to achieve a very small thickness. Furthermore, since the pair of discharge electrodes face each other via the discharge space formed by the holes or recesses, by changing the shape and size of the holes and the like, the facing distance between the discharge electrodes can be freely adjusted while maintaining a constant laminated thickness. Can be set to
[0036]
According to the surge absorber of the second aspect, in the surge absorber of the first aspect, a plurality of pairs of the discharge electrodes facing each other in the discharge space are provided. Even in the case where the discharge becomes impossible, the discharge electrode which is easily discharged next discharges, and the discharge starting voltage can be kept low.
[0037]
According to the method for manufacturing a surge absorber according to claim 3, the first discharge electrode and the second discharge electrode are formed on one ceramic green sheet, and the first discharge electrode and the second discharge electrode are formed on the ceramic green sheet. A hole or a concave portion for cutting an electrode is formed, and another ceramic green sheet is laminated and pressed on the upper and lower sides of the ceramic green sheet, and baked integrally, so that a ceramic green having a plurality of holes and discharge electrodes arranged at predetermined positions. By laminating the sheets, a pair of discharge electrodes can be simultaneously opposed to each discharge space, and a large amount of surge absorbers can be obtained easily and at once.
[Brief description of the drawings]
FIG. 1 is a longitudinal sectional view of a surge absorber according to the present invention.
FIG. 2 is a view as viewed in the direction of arrows AA in FIG. 1;
FIG. 3 is a view taken in the direction of arrows BB in FIG. 2;
FIG. 4 is an exploded perspective view of the surge absorber shown in FIG.
FIG. 5 is an enlarged view of a main part showing a modification of the surge absorber shown in FIG.
FIG. 6 is a longitudinal sectional view of a conventional surge absorber.
[Explanation of symbols]
21 ... Surge absorber 23 ... Insulating material 25 ... Laminated body 27 ... Hole 29 ... Discharge spaces 31a and 31b ... A pair of discharge electrodes 33 ... Base end 35 ... Top end

Claims (3)

A laminate is formed from the plurality of laminated insulating materials,
A discharge space is formed inside the laminate by a hole or a recess provided in the insulating material,
A pair of discharge electrodes formed on the same insulating material face each other in the discharge space. The surge absorber according to claim 1,
A surge absorber, wherein a plurality of pairs of discharge electrodes facing each other in the discharge space are provided by stacking a plurality of the insulating materials on which the pair of discharge electrodes are formed. On at least one ceramic green sheet, a band-shaped first discharge electrode whose base end reaches one end surface of the sheet and whose front end reaches the center portion of the sheet, and a band-shaped first discharge electrode whose base end reaches the other end surface of the sheet and whose front end reaches the center portion of the sheet. Forming a second discharge electrode,
Forming a hole or recess for cutting the first discharge electrode and the second discharge electrode in the center of the ceramic green sheet,
Laminating other ceramic green sheets on top and bottom of the ceramic green sheet and crimping,
A method for manufacturing a surge absorber, wherein the plurality of pressed ceramic green sheets are integrally fired.

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