JP5206384B2 - Surge absorber and manufacturing method thereof - Google Patents

Description

  The present invention relates to a surge absorber and a manufacturing method thereof, and more particularly to a surge absorber including a pair of discharge electrodes and a manufacturing method thereof.

  As a conventional surge absorber, for example, a surge absorber described in Patent Document 1 is known. In the surge absorber, a recess is provided in the main surface of the substrate, and the recess is filled with a resin mixed with conductive powder. A pair of discharge electrodes are provided on the substrate so as to face each other with a gap for discharge. The discharge gap is located on the resin.

  In the surge absorber described in Patent Document 1, when a voltage having a magnitude greater than or equal to a predetermined value is applied between a pair of discharge electrodes, discharge occurs between the discharge electrodes via the resin. As a result, the surge absorber prevents an excessive current from flowing to the subsequent circuit.

  By the way, as the resin, a silicon resin is used in which the resin is less likely to be carbonized by energy during discharge. Silicone resin does not adhere well to substrates such as alumina. Therefore, in the surge absorber described in Patent Document 1, a protective layer such as an epoxy resin is provided so as to cover the silicon resin and the discharge electrode.

However, although a protective layer such as an epoxy resin adheres relatively well to the substrate, it does not adhere well to the discharge electrode. In particular, in the surge absorber, when the substrate is downsized while maintaining the size of the discharge electrode, the area where the discharge electrode is not provided becomes small. As a result, the protective layer and the substrate are not favorably bonded.
JP 2003-297524 A

  Then, the objective of this invention is providing the surge absorber which can suppress that the insulating layer as a protective layer peels from a board | substrate, and its manufacturing method.

  A surge absorber according to a first aspect of the present invention includes a substrate having a first main surface and a second main surface and having a hole in the first main surface, and the first main surface. A second discharge electrode provided on the first main surface so as to be opposed to the first discharge electrode via a gap for discharge; An insulating layer mixed with powder of a conductive material, the insulating layer being provided on the first main surface so as to overlap the gap when seen in a plan view from the normal direction of the first main surface 1 is provided on the first main surface so as to cover the first insulating layer, the first discharge electrode, the second discharge electrode, and the first insulating layer, and is filled in the hole. And a second insulating layer.

  A surge absorber according to a second aspect of the present invention includes a substrate having a first main surface, a second main surface and side surfaces, a first discharge electrode provided on the first main surface, An insulating layer in which a conductive material powder is mixed with a second discharge electrode provided on the first main surface so as to face the first discharge electrode via a discharge gap; A first insulating layer provided on the first main surface so as to overlap the gap when viewed in plan from the normal direction of the first main surface; and the first discharge electrode. And a second insulating layer provided from the first main surface to the side surface so as to cover the second discharge electrode and the first insulating layer.

  A method of manufacturing a surge absorber according to an aspect of the present invention includes a step of preparing a mother substrate having a first main surface and a second main surface, and having a hole in the first main surface; And a second discharge electrode facing the first discharge electrode through a gap for discharge on the first main surface, and an insulating material mixed with powder of a conductive material A step of forming a first insulating layer on the first main surface, the first insulating layer covering the gap, and a part of the insulating sheet by pressure-bonding the insulating sheet to the first main surface And a step of cutting the mother substrate.

  ADVANTAGE OF THE INVENTION According to this invention, it can suppress that the insulating layer as a protective layer peels from a board | substrate.

  Hereinafter, a surge absorber and a manufacturing method thereof according to an embodiment of the present invention will be described.

(First embodiment)
(Surge absorber configuration)
Hereinafter, a surge absorber according to a first embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a view showing a structure of a surge absorber 10a according to the first embodiment. Specifically, FIG. 1A is an external perspective view when the surge absorber 10a is viewed from above. FIG. 1B is an external perspective view of the surge absorber 10a when the protective layer 20 of FIG. FIG. 1C is an external perspective view of the surge absorber 10a as viewed from below. FIG. 1D is a sectional structural view taken along line AA of the surge absorber 10a of FIG. Hereinafter, the direction (normal direction) perpendicular to the main surface of the surge absorber 10a is defined as the z-axis direction, the direction along the long side of the surge absorber 10a is defined as the x-axis direction, and the short side of the surge absorber 10a is defined. The direction along is defined as the y-axis direction. The x axis, the y axis, and the z axis are orthogonal to each other.

  As shown in FIG. 1, the surge absorber 10 a includes a substrate 12, discharge electrodes 14 a and 14 b, a discharge layer 16, external electrodes 18 a and 18 b, connection portions 19 a and 19 b, and a protective layer 20.

  The substrate 12 is a rectangular insulating substrate made of alumina having a thickness of 0.3 mm, for example, and has main surfaces S1 and S2. In addition, the substrate 12 is provided with two circular holes h1 and h2 penetrating between the main surface S1 and the main surface S2. The main surface S1 is a surface located on the positive direction side in the z-axis direction, and the main surface S2 is a surface located on the negative direction side in the z-axis direction.

  The discharge electrode 14a is provided with a thickness of 1.0 μm on the main surface S1 of the substrate 12 and extends in the x-axis direction from the short side of the negative side of the substrate 12 in the x-axis direction to the vicinity of the center of the substrate 12. ing. The discharge electrode 14b is provided on the main surface S1 of the substrate 12 with a thickness of 1.0 μm and extends in the x-axis direction from the short side of the substrate 12 on the positive side in the x-axis direction to the vicinity of the center of the substrate 12. ing. The discharge electrode 14 a and the discharge electrode 14 b are opposed to each other with a discharge gap G in the vicinity of the center portion of the substrate 12. The discharge electrodes 14a and 14b are made of a metal having excellent conductivity, such as Ag, Pd, Cu, Au, or an alloy thereof. The discharge gap G is preferably 5 μm or more and 15 μm or less.

  The discharge layer 16 is, for example, a mixture of an insulating resin such as silicon resin and conductive fine powder. As shown in FIGS. 1B and 1D, the discharge layer 16 is viewed in plan from the z-axis direction. Sometimes, it is provided on the main surface S1 so as to overlap the gap G for discharge. In the present embodiment, the discharge layer 16 is provided so as to cover the gap G. The discharge layer 16 has a dome shape with a thickness of several tens of μm, as shown in FIG. The discharge layer 16 normally has a high impedance, but when a very high voltage such as static electricity is applied between the discharge electrode 14a and the discharge electrode 14b, a discharge is generated between the conductive fine powders. Occurs in a low impedance state.

  As shown in FIG. 1C, the external electrode 18a is provided on the main surface S2 of the substrate 12, and overlaps the discharge electrode 14a when viewed in plan from the z-axis direction. Further, as shown in FIG. 1C, the external electrode 18b is provided on the main surface S2 of the substrate 12, and overlaps the discharge electrode 14b when viewed in plan from the z-axis direction.

  As shown in FIGS. 1B to 1D, the hole h1 has a diameter of 0.1 mm at a position overlapping the discharge electrode 14a and the external electrode 18a when viewed in plan from the z-axis direction. Is provided. As shown in FIG. 1D, the hole h1 has a shape that increases in area when viewed from the z-axis direction as it goes from the main surface S1 to the main surface S2. That is, the hole h1 has a tapered shape in which the diameter increases from the main surface S1 to the main surface S2. And the connection part 19a is provided in the internal peripheral surface of the hole h1, and has connected the discharge electrode 14a and the external electrode 18a.

  As shown in FIGS. 1B to 1D, the hole h2 has a diameter of 0.1 mm at a position overlapping the discharge electrode 14b and the external electrode 18b when viewed in plan from the z-axis direction. Is provided. As shown in FIG. 1D, the hole h2 has a shape that increases in area when viewed from the z-axis direction as it goes from the main surface S1 to the main surface S2. That is, the hole h2 has a tapered shape such that the diameter thereof increases from the main surface S1 to the main surface S2. And the connection part 19b is provided in the internal peripheral surface of the hole h2, and has connected the discharge electrode 14b and the external electrode 18b.

  The protective layer 20 is a rectangular insulating sheet provided over the entire surface of the main surface S1, and is made of a relatively soft thermosetting resin (for example, an epoxy resin or a phenol resin). The protective layer 20 covers the discharge electrodes 14 a and 14 b and the discharge layer 16. The protective layer 20 also enters the holes h1 and h2, as shown in FIG. That is, the holes h 1 and h 2 are filled with the protective layer 20.

  As shown in FIG. 1 (e), the holes h1 and h2 have a shape that increases in area when viewed in plan from the z-axis direction as the main surface S1 moves from the main surface S1 to the main surface S2. You may have in at least one part between main surface S2. FIG. 1E is a cross-sectional structure view taken along line AA of the surge absorber 10a according to the modification.

(Production method)
About the surge absorber 10a comprised as mentioned above, the manufacturing method is demonstrated referring drawings below. FIG. 2 is a process cross-sectional view at the time of manufacturing the surge absorber 10a.

  First, a mother substrate 12m made of alumina or the like is prepared. The mother substrate 12m is an aggregate of the substrates 12 before being cut. Next, holes h1 and h2 as shown in FIG. 1 are formed in the mother substrate 12m. The holes h1 and h2 may be formed, for example, by blasting or by irradiating a laser beam. When the holes h1 and h2 are formed by blast processing or laser beam irradiation, it is desirable to perform processing from the main surface S2 side. Thereby, holes h1 and h2 having a taper as shown in FIG. 1D can be formed.

  Next, discharge electrodes 14a and 14b, external electrodes 18a and 18b, and connection portions 19a and 19b as shown in FIG. Specifically, the substrate 12 is placed in a box having an opening in a region where the discharge electrodes 14a and 14b, the external electrodes 18a and 18b, and the connection portions 19a and 19b are to be formed. Next, a film of a conductive material mainly composed of Ag, Pd, Cu, Au, or an alloy thereof is formed by vapor deposition or plating. Thereby, the discharge electrodes 14a and 14b, the external electrodes 18a and 18b, and the connection portions 19a and 19b are formed on the substrate 12.

  Next, as shown in FIG. 1D, the discharge layer 16 is formed on the mother substrate 12m so as to cover the discharge gap G. More specifically, conductive fine powder is mixed in a thermosetting rubber, a synthetic resin, or the like, and this is dissolved in an organic solvent to form a liquid transient voltage protection material as a gap G between the discharge electrode 14a and the discharge electrode 14b. The target position is continuously dropped or printed by dispensing or screen printing, and this is dried and cured. At this time, the discharge layer 16 has a dome shape due to the surface tension of the liquid transient voltage protection material.

  Next, as shown in FIG. 2, the mother sheet 20m is pressure-bonded so as to cover the entire main surface of the mother substrate 12m. The mother sheet 20m is an aggregate of the protective layers 20 before being cut. At this time, as shown in FIG. 2 (a), the mother sheet 20m is placed on the mother substrate 12m while being sucked from the main surface S2 side, and then crimped. Thereby, the air existing in the gap between the mother substrate 12m and the mother sheet 20m is exhausted from the gap through the holes h1 and h2. Further, since the mother sheet 20m is relatively soft, it penetrates into the holes h1 and h2 as shown in FIG. Thereby, the holes h1 and h2 are filled with the mother sheet 20m.

  Next, the mother substrate 12m is cut along the cut line C shown in FIG. 2 to obtain individual surge absorbers 10a as shown in FIG. If necessary, Ni plating / Sn plating may be applied to the surfaces of the external electrodes 18a and 18b. Thereby, the surge absorber 10a is completed.

(effect)
According to the surge absorber 10a and the manufacturing method thereof as described above, the protective layer 20 enters the holes h1 and h2. Therefore, in the surge absorber 10 a, the protective layer 20 comes into contact with the connection portion 19 in addition to the substrate 12. As a result, according to the surge absorber 10a, it is possible to prevent the protective layer 20 from being peeled from the substrate 12.

  Further, the holes h1 and h2 penetrate between the main surface S1 and the main surface S2. Therefore, as will be described below, the substrate 12 and the protective layer 20 can be more effectively adhered to each other. FIG. 3 is a process sectional view at the time of manufacturing the surge absorber 100 according to the comparative example. 2 and 3, the same reference numerals are assigned to common configurations.

  The surge absorber 100 shown in FIG. 3 is not provided with holes h1 and h2. In this case, even if suction is performed when the mother sheet 20m is pressed, the air is exhausted only from the gap between the mother substrate 12m and the mother sheet 20m as shown in FIG. Therefore, a part of the air remains between the mother board 12m and the mother sheet 20m as shown in FIG. Therefore, in the surge absorber 100, the substrate 12 and the protective layer 20 do not adhere well.

  On the other hand, the surge absorber 10a shown in FIG. 2 is provided with holes h1 and h2. In this case, if suction is performed when the mother sheet 20m is pressed, air is exhausted from the holes h1 and h2 in addition to the gap between the mother substrate 12m and the mother sheet 20m, as shown in FIG. become. Therefore, in the surge absorber 10a, air hardly remains between the mother board 12m and the mother sheet 20m as compared with the surge absorber 100. Therefore, in the surge absorber 10a, the substrate 12 and the protective layer 20 are in good contact.

  Further, in the surge absorber 10a, as shown in FIG. 1D, the holes h1 and h2 have a taper. Therefore, when the protective layer 20 enters the holes h1 and h2, the protective layer 20 becomes difficult to be pulled out due to the anchor effect. As a result, the substrate 12 and the protective layer 20 come into better contact.

  In the surge absorber 10a, as described below, it is not necessary to form an electrode after the cutting shown in FIG. 2B, so that the manufacturing process can be reduced. More specifically, when the discharge electrodes 14a and 14b are provided on the main surface S1 of the substrate 12 and the external electrodes 18a and 18b are provided on the main surface S2 of the substrate 12, generally, the discharge electrodes It is necessary to provide connection portions on the side surface of the substrate 12 to connect the external electrodes 18a and 18b to the external electrodes 18a and 18b.

  However, the side surface of the substrate 12 is a portion that is exposed after the mother substrate 12m is cut. For this reason, when forming the connection portion on the side surface of the substrate 12, it is necessary to form the connection portion separately from the discharge electrodes 14a and 14b and the external electrodes 18a and 18b after the mother substrate 12m is cut.

  On the other hand, in the surge absorber 10a, the discharge electrodes 14a and 14b are connected to the external electrodes 18a and 18b by connection portions 19a and 19b provided on the inner peripheral surfaces of the holes h1 and h2. The holes h1 and h2 are provided at the preparation stage of the mother substrate 12m. Therefore, the inner peripheral surfaces of the holes h1 and h2 are already exposed before the mother substrate 12m is cut. Therefore, the connecting portions 19a and 19b can be formed before the mother substrate 12m is cut. That is, as shown in the manufacturing method, the connection portions 19a and 19b can be formed simultaneously with the discharge electrodes 14a and 14b and the external electrodes 18a and 18b. Therefore, according to the surge absorber 10a, the manufacturing process can be reduced.

(Second Embodiment)
Hereinafter, a surge absorber according to a second embodiment of the present invention will be described with reference to the drawings. FIG. 4 is a view showing the structure of the surge absorber 10b according to the second embodiment. Specifically, FIG. 4A is an external perspective view when the surge absorber 10b is viewed from above. FIG. 4B is an external perspective view of the surge absorber 10b when the protective layer 20 of FIG. 4A is seen through. FIG. 4C is an external perspective view of the surge absorber 10b as viewed from below. FIG. 4D is a sectional structural view taken along line AA of the surge absorber 10b of FIG. Hereinafter, the direction perpendicular to the main surface of the surge absorber 10b is defined as the z-axis direction, the direction along the long side of the surge absorber 10b is defined as the x-axis direction, and the direction along the short side of the surge absorber 10b is defined as y. It is defined as the axial direction. The x axis, the y axis, and the z axis are orthogonal to each other.

  The difference between the surge absorber 10a and the surge absorber 10b is that the surge absorber 10b is provided with grooves g1 and g2 instead of the holes h1 and h2. Below, the surge absorber 10b is demonstrated centering on this difference.

  In the surge absorber 10b, grooves g1 and g2 are provided on the side surfaces S3 and S4 located at both ends in the x-axis direction of the substrate 12, respectively. Each of the grooves g1 and g2 extends from the main surface S1 to the main surface S2, and has a semicircular shape when viewed in plan from the z-axis direction.

  As shown in FIG. 4, the connecting portions 19a and 19b are provided on the inner peripheral surfaces of the grooves g1 and g2, respectively, and connect the discharge electrodes 14a and 14b to the external electrodes 18a and 18b.

  The protective layer 20 is a rectangular insulating sheet provided over the entire surface of the main surface S1, and is made of a thermosetting resin. The protective layer 20 covers the discharge electrodes 14 a and 14 b and the discharge layer 16. Furthermore, as shown in FIG. 4D, the protective layer 20 is also provided in the grooves g1 and g2. Thus, the protective layer 20 is provided from the main surface S1 to the side surfaces S3 and S4. Since the other structure of the surge absorber 10b is the same as the other structure of the surge absorber 10a, description thereof is omitted.

  Next, a method for manufacturing the surge absorber 10b will be described. FIG. 5 is a process cross-sectional view at the time of manufacturing the surge absorber 10b.

  In the surge absorber 10b, a plurality of holes H having a diameter of 0.3 mm to be the grooves g1 and g2 are formed in the mother substrate 12m. Specifically, as shown in FIG. 5, a hole H obtained by combining the groove g1 and the groove g2 is formed in the mother substrate 12m. Since the formation method of the hole H is the same as the formation method of the holes h1 and h2, description thereof is omitted. The method of forming the discharge electrodes 14a and 14b, the external electrodes 18a and 18b and the connection portions 19a and 19b in the surge absorber 10b is also the same as that of the discharge electrodes 14a and 14b, the external electrodes 18a and 18b and the connection portions 19a and 19b in the surge absorber 10a. Since it is the same as the forming method, the description is omitted. Further, the method for crimping the mother sheet 20m in the surge absorber 10b is the same as the method for crimping the mother sheet 20m in the surge absorber 10a, and the description thereof will be omitted.

  Next, the mother substrate 12m is cut along the cut line C shown in FIG. 5 to obtain individual surge absorbers 10b as shown in FIG. At this time, the cut line passes through the hole H. Thereby, the hole H is divided | segmented into the groove | channel g1 and the groove | channel g2. The surge absorber 10b is completed through the above steps.

  According to the surge absorber 10b configured as described above, the same operational effects as the surge absorber 10a can be achieved.

(Other embodiments)
The surge absorber according to the present invention is not limited to the surge absorbers 10a and 10b, and can be changed within the scope of the gist thereof.

  FIG. 6 is a view showing the structure of a surge absorber 10c according to another embodiment. FIG. 6A is an external perspective view of the surge absorber 10c as viewed from above. FIG. 6B is an external perspective view of the surge absorber 10c when the protective layer 20 of FIG. 6A is seen through. FIG. 6C is an external perspective view of the surge absorber 10c as viewed from below. FIG. 6D is a sectional structural view taken along line AA of the surge absorber 10c of FIG. Hereinafter, the direction perpendicular to the main surface of the surge absorber 10c is defined as the z-axis direction, the direction along the long side of the surge absorber 10c is defined as the x-axis direction, and the direction along the short side of the surge absorber 10c is defined as y. It is defined as the axial direction. The x axis, the y axis, and the z axis are orthogonal to each other.

  As shown in FIG. 6, the protective layer 20 may not cover the entire main surface S1. In this case, since a part of the discharge electrode 14a is exposed from the protective layer 20, the external electrode 18a and the connection portion 19a corresponding to the discharge electrode 14a are not necessary. Therefore, in the surge absorber 10c, the external electrode 18b is formed on the entire main surface S2. The discharge electrode 14a is connected to an external circuit by wire bonding, for example. The surge absorber 10c configured as described above can achieve the same effects as the surge absorber 10a.

Fig.1 (a) is an external appearance perspective view when the surge absorber which concerns on 1st Embodiment is seen from upper direction. FIG. 1B is an external perspective view of the surge absorber when the protective layer of FIG. FIG. 1C is an external perspective view of the surge absorber as viewed from below. FIG. 1D is a sectional structural view taken along line AA of the surge absorber of FIG. FIG.1 (e) is a cross-section figure in AA of the surge absorber which concerns on a modification. It is process sectional drawing at the time of manufacture of the surge absorber of FIG. It is process sectional drawing at the time of manufacture of the surge absorber which concerns on a comparative example. Fig.4 (a) is an external appearance perspective view when the surge absorber which concerns on 2nd Embodiment is seen from upper direction. FIG. 4B is an external perspective view of the surge absorber when the protective layer of FIG. 4A is seen through. FIG. 4C is an external perspective view of the surge absorber as viewed from below. FIG. 4D is a sectional structural view taken along line AA of the surge absorber of FIG. It is process sectional drawing at the time of manufacture of the surge absorber of FIG. Fig.6 (a) is an external appearance perspective view when the surge absorber which concerns on other embodiment is seen from upper direction. FIG. 6B is an external perspective view of the surge absorber when the protective layer of FIG. 6A is seen through. FIG. 6C is an external perspective view of the surge absorber as viewed from below. FIG. 6D is a sectional structural view taken along line AA of the surge absorber in FIG.

Explanation of symbols

C cut line G gap h1, h2, H hole S1, S2 main surface S3, S4 side surface g1, g2 groove 10a-10c surge absorber 12 substrate 12m mother substrate 14a, 14b discharge electrode 16 discharge layer 18a, 18b external electrode 19a, 19b Connection part 20 Protective layer 20m Mother sheet

Claims (13)

A substrate having a first main surface and a second main surface, and having a hole in the first main surface;
A first discharge electrode provided on the first main surface;
A second discharge electrode provided on the first main surface so as to face the first discharge electrode via a discharge gap;
An insulating layer mixed with powder of a conductive material, the insulating layer being provided on the first main surface so as to overlap the gap when seen in a plan view from the normal direction of the first main surface 1 insulating layer;
A second insulating layer provided on the first main surface so as to cover the first discharge electrode, the second discharge electrode, and the first insulating layer, and filling the hole When,
Having
Surge absorber characterized by The hole penetrates between the first main surface and the second main surface;
The surge absorber according to claim 1. The hole comprises at least a first hole and a second hole,
A first external electrode and a second external electrode provided on the second main surface;
A first connection portion provided on an inner peripheral surface of the first hole and connecting the first discharge electrode and the first external electrode;
A second connection portion provided on an inner peripheral surface of the second hole, and connecting the second discharge electrode and the second external electrode;
Further comprising
The surge absorber according to claim 2. The hole has a shape that increases in area when viewed from the normal direction of the first main surface as it goes from the first main surface to the second main surface. Having at least a portion between the surface and the second main surface;
The surge absorber according to any one of claims 1 to 3. The second insulating layer covers the entire surface of the first main surface;
The surge absorber according to any one of claims 1 to 4, wherein A substrate having a first main surface, a second main surface and side surfaces;
A first discharge electrode provided on the first main surface;
A second discharge electrode provided on the first main surface so as to face the first discharge electrode via a discharge gap;
An insulating layer mixed with powder of a conductive material, the insulating layer being provided on the first main surface so as to overlap the gap when seen in a plan view from the normal direction of the first main surface 1 insulating layer;
A second insulating layer provided from the first main surface to the side surface so as to cover the first discharge electrode, the second discharge electrode, and the first insulating layer;
Having
Surge absorber characterized by The side surface is provided with a groove extending from the first main surface to the second main surface,
The second insulating layer is provided inside the groove;
The surge absorber according to claim 6. The groove comprises at least a first groove and a second groove,
A first external electrode and a second external electrode provided on the second main surface;
A first connection portion provided on an inner peripheral surface of the first groove and connecting the first discharge electrode and the first external electrode;
A second connecting portion provided on an inner peripheral surface of the second groove and connecting the second discharge electrode and the second external electrode;
Further comprising
The surge absorber according to claim 7. The second insulating layer covers the entire surface of the first main surface;
The surge absorber according to any one of claims 6 to 8, wherein Preparing a mother substrate having a first main surface and a second main surface, and having a hole in the first main surface;
Forming a first discharge electrode and a second discharge electrode facing the first discharge electrode via a discharge gap on the first main surface;
Forming an insulating layer mixed with a powder of a conductive material on the first main surface, the first insulating layer covering the gap;
Crimping an insulating sheet against the first main surface, and filling the hole with a part of the insulating sheet;
Cutting the mother substrate;
Having
A method of manufacturing a surge absorber characterized by the above. In the step of preparing the mother substrate, preparing a mother substrate provided with a hole penetrating the first main surface and the second main surface;
The method of manufacturing a surge absorber according to claim 10. The hole comprises at least a first hole and a second hole,
Forming a first external electrode and a second external electrode on the second main surface;
Forming a first connecting portion for connecting the first external electrode and the first discharge electrode on an inner peripheral surface of the first hole;
Forming a second connecting portion for connecting the second external electrode and the second discharge electrode on an inner peripheral surface of the second hole;
Further comprising
The method of manufacturing a surge absorber according to claim 11. In the step of cutting the mother substrate, cutting the mother substrate so that a cut line passes through the first hole and the second hole;
The method of manufacturing a surge absorber according to claim 12.

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