JP4254084B2 - Chip-type surge absorber and manufacturing method thereof - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a chip-type surge absorber used for protecting various electronic devices from surges and preventing accidents.
[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 the input side, such as CRT drive circuits, that are susceptible to electric shock caused by abnormal voltage such as lightning surge or static electricity. Used to prevent electronic devices from being destroyed by voltage.
[0003]
The configuration of a conventional chip type surge absorber will be described with reference to FIG. FIG. 3A is an exploded perspective view illustrating the configuration of a conventional chip type surge absorber, and FIG. 3B is a plan view excluding the lid body 25 in FIG. As shown in FIG. 3, the conventional chip type surge absorber 20 has a substrate 21 (insulating substrate) formed of alumina or the like as an insulating material, and a discharge electrode is formed on the plate surface by printing or the like. 22 and 23 are formed facing each other. Both the discharge electrodes 22 and 23 are printed as a paste, followed by a drying process and a baking process, and are divided into discharge electrodes 22 and 23 by a discharge gap 24 described later. Therefore, a discharge gap 24 called a micro gap is provided between the discharge electrode 22 and the discharge electrode 23.
In addition, a box-shaped glass (insulating material) or ceramics (insulating material) lid 25 is formed at the periphery of the discharge electrodes 22 and 23 so as to have a sealed space. Bonded on the substrate 21. This space is a gas atmosphere of a kind suitable for discharge, for example, argon gas. Both ends of the lid 25 and the substrate 21 in the longitudinal direction are covered with terminal electrodes (not shown), and the terminal electrodes and the discharge electrodes 22 and 23 are connected.
[0004]
When a surge voltage is applied between the discharge electrodes 22 and 23 via the discharge gap 24, glow discharge is triggered between the discharge electrodes 22 and 23 via the discharge gap 24, and this discharge is caused by the lid 25 and the substrate 21. Is gradually extended to the base end side of both discharge electrodes 22 and 23 in the form of creeping discharge, and arc discharge occurs between the base end sides of both discharge electrodes 22 and 23. Can be absorbed.
[0005]
[Problems to be solved by the invention]
However, when the discharge electrodes 22 and 23 are formed on the substrate 21 by printing, it is common to perform a baking process after printing. If the baking process is performed in the atmosphere, the discharge electrodes 22 and 23 are used. The surface of the metal to be reacted with the atmosphere forms an insulating material, and the surfaces of the discharge electrodes 22 and 23 are covered with the insulating film of this insulating material. Alternatively, the glass component (insulating substance) contained in the paste when the discharge electrodes 22 and 23 are printed on the substrate 21 floats on the surfaces of the discharge electrodes 22 and 23, and the glass component other than the discharge gap 24 formed later. Covered with an insulating film.
[0006]
It goes without saying that it is difficult to extend the discharge on the surfaces of the discharge electrodes 22 and 23 covered with the insulating film. Therefore, only the discharge gap 24 formed after the discharge electrodes 22 and 23 are formed on the substrate 21. A triggered discharge is made and the discharge does not extend in other parts.
For this reason, the discharge is performed only between the discharge gaps 24 with a very short insulation distance, and the materials of the discharge electrodes 22 and 23 scattered by the discharge contaminate the discharge gap 24. As a result, there is a problem that the insulation resistance of the chip type surge absorber is deteriorated at an early stage.
[0007]
The present invention has been made in view of the above circumstances, and an object thereof is to provide a chip-type surge absorber that suppresses deterioration of insulation resistance against surge and a method for manufacturing the same.
[0008]
[Means for Solving the Problems]
The chip-type surge absorber according to claim 1, wherein an outer peripheral portion of the insulating substrate includes a discharge electrode disposed on the insulating substrate so as to face each other via a discharge gap, and a base end portion of each of the discharge electrodes. In a chip-type surge absorber provided with a lid having a peripheral edge bonded thereon, a cut portion along the discharge extension direction is formed on the surface of the discharge electrode, and the surface of the discharge electrode is formed at the cut portion. The insulating film is removed, and the electrode surface inside the discharge electrode is exposed .
[0009]
By using the discharge electrode with the cut portion formed on the surface in this way, the insulating film covering the surface of the discharge electrode is removed at the cut portion, and the electrode surface inside the discharge electrode is exposed. A glow discharge is triggered in the discharge gap, and the discharge extends along the notch to the base end of the discharge electrode. The depth of the cut portion needs to be deeper than the insulating film thickness covering the surface of the discharge electrode. Further, the discharge electrode may be divided by cutting deeply until the cut portion reaches the insulating substrate. In this case, it is preferable that the electrode surface appears on a plane when the discharge electrode is viewed from above. Furthermore, the length of the cut portion can be selected in accordance with the intended use, and is preferably formed from the discharge gap to the base end portions on both sides of the discharge electrode.
[0010]
The chip-type surge absorber according to claim 2 is the chip-type surge absorber according to claim 1, wherein the cut portion is one or a plurality of cut portions substantially parallel to the discharge extension direction. It is said.
[0011]
By forming the discharge electrode in this way, the discharge is extended linearly from the discharge gap formed in the vicinity of the center portion of the chip-type surge absorber toward the proximal end portion. In addition, since the cut portion can be formed in a constant and easy manner, the exposed electrode surface that can be discharged in the cut portion has a constant shape, and stable discharge is performed up to almost the base end portion of the discharge electrode. In addition, it is suitable to form a notch part to a base end part.
[0012]
A manufacturing method of a chip type surge absorber according to claim 3 includes: a discharge electrode disposed on an insulating substrate so as to face each other with a discharge gap; and a base end portion of each discharge electrode. In a manufacturing method of a chip-type surge absorber provided with a lid having a peripheral edge bonded to an outer peripheral portion, a surface of the discharge electrode is formed after the discharge electrode is printed on the insulating substrate and subjected to a firing step. And a step of forming a notch along the discharge progress direction to remove the insulating film formed on the surface of the discharge electrode to expose the electrode surface inside the discharge electrode .
[0013]
An insulating film is formed on the surface of the discharge electrode after the discharge electrode is printed on the insulating substrate and the firing process is performed. Since this insulating film inhibits the extension of discharge in the discharge electrode, the insulating film is removed by a cut portion after the insulating film is formed. As a result, an easily dischargeable electrode surface is exposed at the cut portion.
[0014]
The manufacturing method of the chip type surge absorber according to claim 4 is the manufacturing method of the chip type surge absorber according to claim 3,
The step of forming the cut portion is a laser beam or dicing.
[0015]
Thus, by performing with a laser beam, the insulating film on the surface of the discharge electrode is removed, and the electrode surface is exposed. Further, the surface is polished by, for example, an outer peripheral ultrathin grindstone in dicing, and the insulating film is removed.
[0016]
DETAILED DESCRIPTION OF THE INVENTION
Next, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a diagram for explaining the overall configuration of a chip-type surge absorber 1 according to this embodiment. FIG. 1A is an exploded perspective view of the chip-type surge absorber 1, and FIG. 2 is a plan view of the chip type surge absorber 1. FIG.
In FIG. 1, reference numeral 2 denotes a substrate 2 (insulating substrate) formed of ceramics which is an insulating material, and both discharge electrodes 3 and 4 are arranged to face each other on this plate surface. Both of these discharge electrodes 3 and 4 are divided by a discharge gap 5 formed of a groove located substantially at the center of the chip type surge absorber 1. Therefore, both the discharge electrodes 3 and 4 are integrally formed in a strip shape at the initial stage of manufacture, and then divided into the discharge electrodes 3 and 4 by the discharge gap 5. The plate surface of the substrate 2 on which both the discharge electrodes 3 and 4 are formed is covered with a lid 7 made of ceramic as an insulating material, and the outer periphery of the plate surface of the substrate 2 and the periphery of the lid 7 The parts are bonded with melted glass (insulating material). An internal space formed by the lid 7 and the substrate 2 is filled with argon gas suitable for discharge.
[0017]
As shown in FIG. 1, a single notch 6 is formed on the surfaces of both discharge electrodes 3, 4 across the discharge gap 5. The cut portion 6 is used to scrape off the surfaces of the discharge electrodes 3 and 4 in a straight line with a laser beam, whereby the insulating film formed on the surfaces of the discharge electrodes 3 and 4 is removed at the cut portion 6.
In addition, since the step of forming the cut portion 6 is performed after the insulating film is formed, this will be described.
[0018]
The discharge electrodes 3 and 4 are printed on the plate surface of the substrate 2 using a conductive paste. At this stage, both the discharge electrodes 3 and 4 described above are integrally formed in a strip shape. The printed substrate 2 is dried and then baked in the atmosphere. At this stage, an insulating material is generated on the surfaces of the discharge electrodes 3 and 4 and is covered with an insulating film.
[0019]
Next, one linear cut portion 6 is formed on the surface of the discharge electrodes 3 and 4 along the longitudinal direction, which is the discharge extension direction, with a laser beam. The depth of the cut portion 6 is set to a depth corresponding to the insulating film thickness on the surfaces of the discharge electrodes 3 and 4. Since it is usually considered that the insulating film thickness is in units of microns, the cut portion 6 is formed by roughening the surface with a laser beam, for example, 1% to 100% of the thickness of the discharge electrodes 3 and 4, more preferably Is set to a depth of 5% to 90%. Of course, you can cut deeper than this.
The length of the cut portion 6 is cut so as to reach both base end portions of the discharge electrodes 3 and 4 and including the central portion of the chip-type surge absorber 1 which is the position of the discharge gap 6 to be formed later. It is.
[0020]
After the cut portions 6 are formed on the surfaces of the discharge electrodes 3 and 4, a single groove is formed at substantially the center of the discharge electrodes 3 and 4 to divide the discharge electrodes 3 and 4. At this stage, the discharge electrodes 3 and 4 are divided into two discharge electrodes 3 and a discharge electrode 4.
[0021]
On the substrate 2 on which both the discharge electrodes 3 and 4 are formed, a lid body 7 that forms a space filled with gas is bonded to the substrate 2. Argon gas suitable for discharge is used as the gas sealed in the space, and ceramics, which is an insulating material, is used as the lid body 7. The lid 7 and the substrate 2 are bonded with melted glass (insulating material).
Terminal electrodes (not shown) are connected to and attached to the respective discharge electrodes 3 and 4 on both sides in the longitudinal direction of the lid body 7.
[0022]
When the surge voltage is applied between the discharge electrodes 3 and 4 via the discharge gap 5 in the chip-type surge absorber 1 in this embodiment formed in this way, the discharge electrodes 3 and 4 are connected via the discharge gap 5. The glow discharge is triggered by this, and the discharge is extended along the cut portion 6. The surface of the discharge electrodes 3 and 4 covered with the insulating film is not easily extended in the discharge, but the extension of the discharge is surely made in the cut portion 6.
[0023]
With the chip-type surge absorber 1 of the present embodiment described above, it is possible to avoid discharging only in the discharge gap 5 with a short insulation distance, and the electrode material of the discharge electrodes 3 and 4 scattered by the discharge contaminates the discharge gap 5. Is suppressed.
FIG. 2 is a graph diagram comparing the values of insulation resistance against surge between the conventional chip type surge absorber (see FIG. 3) and the chip type surge absorber 1 of the present embodiment. According to this, the insulation resistance of the conventional chip type surge absorber decreases as the surge increases, whereas the insulation resistance of the chip type surge absorber 1 of this embodiment is always constant with respect to the surge. It turns out that it is stable.
Therefore, the discharge triggered in the discharge gap 5 is arc-discharged at the base ends of the discharge electrodes 3 and 4, and the deterioration of the insulation resistance is greatly suppressed.
[0024]
Note that the following configuration may be adopted as a modification of the present embodiment.
Although the cut portion 6 has been described as being formed up to the base end portions of the discharge electrodes 3 and 4, the cut portion 6 may be formed up to the middle of the base end portion around the discharge gap 5. In this case, it is desirable to form at least 50% of the length of the discharge electrodes 3 and 4.
According to this, a discharge is made at the end of the cut portion 6 formed partway, and gradually eroded, so that the discharge extends in the extending direction and is prevented from extending in the width direction. A chip type surge absorber can be formed. Further, the discharge gap 5 is prevented from being contaminated, and the deterioration of the insulation resistance is sufficiently suppressed.
[0025]
Moreover, although the number of the notch | incision parts 6 was demonstrated as one linear form, it is good also as increasing the number and discharging, and it is good also as forming a notch diagonally or wavy.
According to this, it is avoided that only the discharge gap 5 is discharged and the discharge gap 5 is not contaminated, and the deterioration of the insulation resistance is sufficiently suppressed.
[0026]
Although the depth of the cut portion 6 has been described as about the thickness of the insulating film, the cut portion 6 may be formed to a depth reaching the substrate 2 to further divide both discharge electrodes 3 and 4.
According to this, it is possible to suppress the deterioration of the insulation resistance equivalent to the above embodiment.
[0027]
【The invention's effect】
As described above, according to the chip-type surge absorber according to claim 1, since the cut portion along the discharge extension direction is formed on the surface of the discharge electrode, the discharge extends at the cut portion. The discharge of only the discharge gap due to the generation of the insulating film is eliminated, the contamination of the discharge gap is avoided, and the deterioration of the insulation resistance can be suppressed.
[0028]
According to the chip type surge absorber according to claim 2, since the cut portion where the discharge is made is one or a plurality of cut portions substantially parallel to the length direction, it can be easily formed. It is possible to provide a high-quality chip-type surge absorber that is inexpensive and can suppress deterioration of insulation resistance.
[0029]
According to the manufacturing method of the chip type surge absorber according to claim 3, the cut portion is formed on the surface of the discharge electrode after the discharge electrode is printed on the insulating substrate and the firing process is performed. A cut portion is formed in the generated state, and the electrode surface can be exposed on the surface of the discharge electrode. Discharge is extended at the notch, so that only the discharge gap due to the generation of the insulation film is eliminated, and the discharge gap is prevented from being contaminated, and a chip type surge absorber that suppresses deterioration of insulation resistance is manufactured. can do.
[0030]
According to the manufacturing method of the chip type surge absorber according to claim 4, since the cut portion is formed by laser beam or dicing, it can be processed easily and accurately, and the deterioration of the insulation resistance can be suppressed at a low cost. A high-quality chip-type surge absorber can be manufactured.
[Brief description of the drawings]
FIG. 1 is a diagram for explaining a schematic configuration of a chip type surge absorber according to an embodiment of the present invention, in which FIG. 1 (a) is an exploded perspective view of the chip type surge absorber, and FIG. It is a top view of the chip type surge absorber removed.
FIG. 2 is a graph showing the relationship between surge and insulation resistance between a conventional chip type surge absorber and a chip type surge absorber according to an embodiment of the present invention.
3A and 3B are diagrams for explaining a schematic configuration of a conventional chip-type surge absorber, in which FIG. 1A is an exploded perspective view of the chip-type surge absorber, and FIG. 1B is a chip-type surge without a cover. It is a top view of an absorber.
[Explanation of symbols]
1 Chip type surge absorber 2 Substrate (insulating substrate)
3, 4 Discharge electrode 5 Discharge gap 6 Notch 7 Lid

Claims (4)

Discharge electrodes disposed opposite to each other via a discharge gap on an insulating substrate, and a lid having a peripheral edge bonded to an outer peripheral portion of the insulating substrate including a base end portion of each discharge electrode. In the chip type surge absorber provided,
The surface of the discharge electrode is formed with a cut portion along the discharge extension direction, and the insulating film covering the surface of the discharge electrode is removed at the cut portion, and the electrode surface inside the discharge electrode is exposed. Chip type surge absorber characterized by In the chip type surge absorber according to claim 1,
The chip-type surge absorber, wherein the cut portion is one or a plurality of cut portions substantially parallel to the discharge extension direction. Discharge electrodes disposed opposite to each other via a discharge gap on an insulating substrate, and a lid having a peripheral edge bonded to an outer peripheral portion of the insulating substrate including a base end portion of each discharge electrode. In the manufacturing method of the chip type surge absorber provided,
After the discharge electrode is printed on the insulating substrate and the firing process is performed, a cut portion is formed along the discharge progress direction on the surface of the discharge electrode, and an insulating film formed on the surface of the discharge electrode is formed. A method of manufacturing a chip-type surge absorber, comprising a step of removing and exposing an electrode surface inside the discharge electrode . In the manufacturing method of the chip type surge absorber according to claim 3,
A method of manufacturing a chip-type surge absorber, wherein the step of forming the cut portion is a laser beam or dicing.

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