JPH09223566A - Surge absorption element - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a surface mounting type surge absorption element in which mounting and manufacturing are easy, and life is long by arranging one pair of electrodes on a plane substrate, and forming discharge space through an airtight cap provided so as to cover the electrode and a micro gap. SOLUTION: A pair of electrodes 22a, 22a', 22b, 22b' are provided on an insulation substrate 21 main surface, and a micro gap 23 is provide between the pair of electrodes 22a', 22b'. The pair of electrodes are composed of electrode portions 22a', 22b' of high electric resistance in the vicinity of the micro gap 23, and the electrode portions 22a, 22b of relatively low electric resistance connected to an outside electrode or a terminal. An airtight cap 25 is provided so as to cover the pair of electrodes, and closed space is formed between the substrate having the electrodes. A pair of electrode terminals 27a, 27b are provided in the vicinity of both end faces of the substrate 21.

Description

The present invention relates to a microgap or gap type surge absorber, and more particularly to a surface mount type surge absorber which is advantageous for automatic mounting on a printed circuit board.

[Prior Art] As shown in FIG. 1, a surge absorbing element for protecting a communication device such as a telephone and a facsimile device has a cylindrical insulator surface in which a pair of electrodes 1a and 1b forming a microgap 2 are cylindrical. , A pair of cap electrodes 3a and 3b with lead wires are attached to each of the pair of electrodes 1a and 1b on the insulator, which is hermetically sealed with a glass tube 5 and the inside is depressurized. As is apparent from FIG. 1, the conventional microgap type surge absorbing element has a lead wire 4 having a length of about 25 mm, and when mounted on a printed circuit board, the lead wire is cut to an appropriate length,
Bending is required, and then lead wires are inserted into the holes of the printed circuit board and soldered. However, as is well known, such a mounting and mounting method on a printed circuit board is a labor-intensive method, and many electronic components have been changed to surface mounting type so-called surface mounting type electronic components. Further, these conventional surge absorbing elements have a processing step along the circumference of the surface of a cylindrical insulator, which is an obstacle to improving productivity and is a hindrance to cost reduction. Furthermore, the heat generated by the discharge during surge absorption is radiated mainly through the thin lead wires,
As a result, the thermal resistance is large, which causes a temperature rise in the element.
Deterioration of the device, particularly deterioration of the electrodes in the micro gap or the gap portion was brought about. It is an object of the present invention to provide a microgap or gap type surge absorber that is easy to mount, easy to manufacture, and has a long life.

[Means for Solving the Problems] The gist of the present invention is to electrically insulate each other on the same plane of a substrate,
A pair of electrodes, which are arranged so as to form a microgap or a gap and have a high electric resistance in the vicinity of the microgap or the gap, and an electrode part having a relatively low electric resistance that communicates with an external electrode or a terminal. An airtight cap or lid that includes the microgap or the gap and the pair of electrodes around the gap and covers the flat surface of the substrate, and a pair of electrodes provided near both end surfaces of the substrate. It is a microgap or a gap type surge absorber. In the present invention, a pair of electrodes, which are conventionally provided on the surface of a cylindrical insulator, are arranged so as to form a microgap,
It is arranged on a flat substrate and the discharge gap is formed by an airtight cap that is provided so as to cover the electrodes and the microgap. It is possible to process a large number of arrayed element materials or to process them all at once, and it is possible to realize extremely high productivity as compared with the prior art. Further, the electrode formed on the plane is composed of a pair of electrodes including an electrode portion having a high electric resistance in the microgap or in the vicinity of the gap and an electrode portion having a relatively low electric resistance communicating with an external electrode or a terminal. Therefore, after the discharge is started, the discharge current can be prevented from concentrating on the electrodes in the microgap portion, and the deterioration of the electrodes can be prevented. Further, by arranging external electrodes for mounting on the printed board on the end surface of the planar board, surface mounting on the printed board by a pair of external electrodes on the same plane is made possible. Next, the surge absorbing element of the present invention will be described by way of specific examples, but the present invention is not limited to the description.

[Embodiment 1] FIG. 2 shows an example of a surge absorber according to the present invention by a schematic sectional view A and a plan view B. A pair of electrodes 22a, 22a ', 22b, 22 is formed on the main surface of the insulating substrate 21 such as mullite or alumina by screen printing or the like.
b'is provided, and the micro gap 23 is provided between the pair of electrodes 22a ', 22b'. These pair of electrodes are composed of electrode portions 22a 'and 22b' having a high electric resistance in the microgap or in the vicinity of the gap, and electrode portions 22A having a relatively low electric resistance communicating with external electrodes or terminals.
It consists of 2b. An airtight cap 25 is provided so as to cover the pair of electrodes to form a hermetically sealed space with the substrate having the electrodes. The airtight cap 25 is preferably made of metal such as Kovar, glass, or ceramic. Further, glass frit is suitable for sealing the airtight cap 25 to the surface of the substrate 21, but in the case of a metal cap or the like, solder can also be used. In this case, the electrode 22 made of solder
electrodes 22a and 22b to prevent short circuit between a and 22b
It is necessary to cover the surface with an insulating film such as a glass film. A conductive film such as silver-palladium, molybdenum alloy, or tungsten alloy, which can be soldered in advance, is provided on the substrate surface of the soldering part.
It is desirable to form them by screen printing / firing method, vapor deposition method, sputtering method, CVD (chemical vapor deposition) or the like. Further, as the solder for sealing, it is desirable to use high-temperature solder that does not melt at the solder melting temperature during surface mounting of the surge absorbing element.
In the figure, 26 is a sealing material such as glass frit or solder for sealing the airtight cap 25 on the surface of the substrate 21. Further, at the time of sealing the airtight cap, the glass frit or solder is melted and sealed by evacuating and evacuating and partially heating with argon gas or the like and then heating under a predetermined pressure. As is clear from the above description, a surface mountable surge absorbing element is possible. Furthermore, as a result of the fact that such elements can utilize highly mass-producible film forming technology such as screen printing technology, surface-mount type surge absorption elements, which are advantageous in terms of mounting,
It is also clear that it can be obtained with high mass productivity. Furthermore, the following effects in the characteristics of the surge absorber were confirmed,
That is, when compared with the conventional surge absorbing element shown in FIG. 1, these elements radiate heat through a lead wire having a large thermal resistance and having a diameter of about 0.5 mm, whereas in the surge absorbing element of this embodiment, The cross-sectional area of the electrode is four times or more compared with the cross-sectional area of the electrode, which is formed by the wide electrode terminals 27a and 27b regardless of the lead wire, the heat dissipation is improved, and the discharge started at the microgap portion is generated on the electrode. Progress, 22
Since the electrodes 22a 'and 22b' near the micro gap 23 which reach a and 22b are high resistance electrodes, the discharge current is less likely to flow, the discharge is not concentrated in the micro gap portion, and the electrodes facing the micro gap are provided. Can be prevented from deterioration. As a result, of course, the life of the surge absorbing element was extended, and the surge withstand capability could be greatly improved by the conventional element. In the figure, the electrode portion having a high electric resistance and the electrode portion 2
2a 'and 22b' are formed by sputtering a high resistance metal film of tungsten, molybdenum, etc., electron beam evaporation method, C
It is desirable to reduce deposition by the VD method (chemical vapor deposition method) or the like, and the electrode portion 22a having a low electric resistance.
It is desirable that, and 22b be formed of a solderable metal or alloy such as copper or kovar by the same sputtering method, electron beam evaporation method, CVD method (chemical vapor deposition method) or the like as described above. In this case, patterning is performed by photoetching. Further, it is possible to use not only such a thin film technology but also a thick film technology. In this case, the electrode portions 22a ′ and 22b ′ having a high electric resistance are formed by a resistance film formed by printing and firing, and a low electric resistance is obtained. The electrode portions 22a and 22b of the resistor can be formed of a conductive film by printing / baking. In such a case, the pattern can be formed into a pattern and the etching process is unnecessary.

[Embodiment 2] FIG. 3 is a schematic sectional view showing another embodiment of the present invention. In this embodiment, a conductive substrate such as aluminum is used as the substrate 31 and is a conductive material. Therefore, in the case of an aluminum substrate, the surface of the substrate is
It is covered with an insulating film 38 such as an aluminum oxide film such as ₂ O ₃ . When such a material is used, since the substrate itself has a high thermal conductivity, heat dissipation generated by a surge of a large current is significantly improved during operation as a surge absorbing element. As a result, it is possible to provide a surge absorbing element in which the characteristics of the surge absorbing element are less likely to deteriorate. In the figure, 32a and 32b are high resistance electrode portions, 33 is a microgap, 34a and 34b are low resistance electrode portions, 35 is an airtight cap, and 36
Is an adhesive for airtightly adhering the airtight cap 35, 37a,
37b is an electrode terminal made of Kovar or the like. Further, when compared with the conventional surge absorbing element shown in FIG. 1, these elements radiate heat by a lead wire having a large thermal resistance and having a diameter of about 0.5 mm, whereas in the surge absorbing element of the present embodiment, Since the heat is dissipated from the entire surface of the substrate 31 having excellent heat conduction, the heat dissipation is remarkably improved, and the discharge current to the electrode portion having a high electric resistance facing the gap is suppressed as described in the second embodiment. Together with this, deterioration due to heat during discharge can be prevented, the life of the surge absorbing element can be extended, and surge withstand can be greatly improved.

[Embodiment 3] FIG. 4 is a schematic cross-sectional view showing another embodiment of the present invention, in which 41 is an insulating substrate, 42a,
42a ', 42b, 42b' are a pair of electrodes formed on the insulating substrate, and 43 is a gap provided between the pair of electrodes 42a, 42b. In the figure, 42a '
42a 'and 42b' are electrodes having low electric resistance,
b'is an electrode part having a high electric resistance. Further, 44 is an insulating film such as a glass film adapted to the electrode and the cap material,
Reference numeral 45 is a lid for hermetically sealing. That is, the electrodes are conductive, and when solder is used as a sealing material or a metal cap is used, the pair of electrodes are short-circuited by the solder or the cap and do not operate as a surge absorbing element. It is necessary to provide a uniform insulating film. Compared to the first and second embodiments, the present embodiment is different in that it is sealed by a flat lid. When a flat lid is used, there is an advantage that a cap molding operation unlike the case of a cap is not required and an expensive mold is not required, and since it is a flat plate, there is a large degree of freedom in selecting a material. However, a thick sealing material 48 is necessary in order to make the gap between the pair of electrodes 42a and 42b and the lid appropriate and to secure the airtight space to be formed. It is effective to thicken the sealing material or to raise it with a material having a higher melting point than the sealing material such as glass frit in advance before applying the sealing material.

[Embodiment 4] FIG. 5 shows another embodiment of the present invention. This is an example in which the price of the surge absorbing element is further reduced due to the formation of the electrode terminal portion in the examples 1 to 3. FIG. 5A is a plan view and FIG. 5B is a schematic sectional view. This is a structure in which a pair of electrodes are taken out on the back surface through the through holes by a printing and firing technique for a ceramic substrate having multiple through holes. In this case, it is not necessary to attach special electrode terminals, The cost reduction effect is large due to the reduction of man-hours. In the figure, 51 is a ceramic substrate, 52a, 52a ', 52b, 5
2b 'is a pair of electrodes (in the figure, the state before the gap formation by laser cutting is shown), and 52a' and 52b '
Is a high electric resistance electrode portion, 52a and 52b are low electric resistance electrode portions and external connection electrodes, and 59a and 59b are conductive films for connecting electrodes on the front and back surfaces of the substrate 51.

[Embodiment 5] Another embodiment of the present invention is shown by the schematic sectional view of FIG. 6A and the plan view of FIG. 6B. In the figure, 61 is a substrate, 62a, 62b, 62a ', 62.
Reference numeral b'denotes electrodes, and these electrodes are composed of portions having different resistivities. That is, the electrode portion 62 having high electric resistance
a ', 62b', and 62a, 62b having a low electric resistance. As a result, the discharge started at the gap 63 expands on the electrodes, and the electrodes 62a, 6
It is possible to make it easy to progress to the area between 2b, prevent the discharge from being concentrated, and improve the life of the micro gap portion electrode which is easily damaged by heat. In the figure, 65 is a cap, 66 is a sealing material, and 67a and 67b.
Is a pair of electrode terminals. As the electrodes 62a 'and 62b', refractory metals such as tungsten, molybdenum, and tantalum, which have high thermal stability, are formed by an electron beam evaporation method, a sputtering method, and a CVD (chemical vapor deposition) method. Dozens of Angstroms to 100
A thickness of 0Λ is effective. Further, a semiconductor such as Si, which has a relatively high melting point and whose resistivity changes depending on the doping amount of impurities, is also effective. For the electrodes 62a and 62b, gold,
Copper, nickel, etc. are effective, but it is also effective to increase the film thickness of the refractory metal such as tungsten, tantalum, molybdenum to lower the resistance, and in this case, it becomes one kind of material, and equipment It is advantageous in terms of investment and process control.

[Sixth Embodiment] In the fifth embodiment, the electrode portions 62a 'and 62b' having high electric resistance are formed by thick film resistance by printing and firing, and the electrode portions 62a and 62b having low electric resistance are formed by printing and firing. Similar effects were obtained also in the examples using the thick conductive film. In such a case, the electrodes 62a and 62b and 67a and 67b can be formed of the same thick-film conductive film, which has the effect of simplifying the process.

[Embodiment 7] A method for forming a substrate with electrodes for realizing the present invention will be specifically described. 7A, 7B, and 7C are views for explaining the embodiment, in which FIGS. 7A and 7B are plan views, and FIG. 7C is a schematic cross-sectional view taken along line ab of FIG. 7A. is there. The substrate 71 is an insulating substrate such as ceramic or a conductive substrate such as aluminum coated with an insulating film such as alumite. In FIG. 7A, a thick film resistor 72 is formed on the surface of the substrate by a printing / firing technique, and subsequently, as shown in FIG. 7B, a pair of thick film conductors 72a and 72b are formed by the same printing / firing technique. It is formed. The thick film conductor communicates with the back surface through the through hole 79 and serves as an electrode for soldering at the time of mounting on the printed circuit board on the back surface. FIG. 7C shows the formation of the microgap 73 by means of a laser cutter, whereby the microgap is opposed at the microgap,
A pair of electrode portions 72a 'and 72b' having high electric resistance
Is formed. According to such a method, pattern formation of electrodes and the like on the same substrate is performed at a time on a substrate-by-substrate basis, and depending on the size of the substrate, several hundreds to several thousands can be processed per substrate. According to the invention, extremely high productivity can be realized.

[Embodiment 8] A method of forming a substrate with electrodes for realizing the present invention will be described in detail. 8A, 8B and 8C are views for explaining the embodiment, wherein FIGS. 8A and 8B are plan views and FIG. 8C is a in FIG. 7A.
-B is a schematic cross-sectional view of FIG. The substrate 81 is an insulating substrate such as ceramic or a conductive substrate such as aluminum coated with an insulating film such as alumite. FIG. 8A relates to formation of an electrode portion having a high electric resistance. In the figure, 81 is a substrate, and 82 is a thin film formed by a sputtering method, an electron beam evaporation method, a CVD method or the like. In the embodiment, the thin film is composed of a first layer of a metal having a high melting point and a high resistance such as tungsten and molybdenum, and a second layer of a solderable metal film such as copper, nickel and kovar. In FIG. 8B, the metal film is patterned by etching to form a pair of electrodes according to the present invention.
In the figure, reference numerals 82a and 82b denote electrode portions having a low electric resistance, and reference numerals 82a 'and 82b' denote electrode portions having a high electric resistance. 83 is a microgap. FIG. 8C shows an electrode terminal portion connected and formed on the back surface through the through hole 89 by printing and firing. Similar to the seventh embodiment, also in this embodiment, the thin film formation can be performed in substrate units, so that extremely high productivity can be realized. In this embodiment, two layers were continuously formed as the thin film formation. However, after forming a high melting point and high resistance thin film and pattern etching, a metal film for the second low electric resistance electrode portion is formed. Of course, it is possible to form, and the same effect can be obtained.

[Embodiment 9] Another embodiment relating to the formation of an electrode portion having a high electric resistance necessary for the present invention will be described. By reducing the planar shape (or electrode area) of the electrode formed as a single layer, it is possible to form an electrode portion having high electric resistance. 9A and 9B are plan views showing another embodiment according to the present invention, and FIG. 9C is a plan view showing the other embodiment.
3 is a schematic cross-sectional view of FIG. In the figure, 91 is a substrate,
Numerals 92a and 92b are a pair of electrodes, and are composed of several tens of ÅΛ to 10,000 Å thin films made of materials such as W and Mo or printed and fired resistors. In the present invention, the gap 9
A part of these electrodes near 3 is removed, the planar shape (or cross-sectional area) of the electrodes is reduced, and the resistance is increased. In the figure, 100 and 100 'are electrode removal parts, which increases the resistance of the electrodes 72a, 72b to the gap part at 72a', 72b ', which facilitates discharge easily at 92a and 92b. And the life of the electrode in the gap portion is extended. When the formation of the gap 93 and the formation of the removed portions 100 and 100 ′ are performed by the photoetching method, they can be collectively performed in the same process. It is also possible to carry out as a continuous process with a laser cutter as in the above-mentioned embodiment,
However, in this case, if the outer periphery of the removed portion is linearly removed so as to be surrounded by a laser, the enclosed portion is separated from the surrounding electrode, so that the same effect as that of the removal can be obtained and the laser processing time can be shortened. It will be possible. Of course, it is possible to etch and remove only the periphery of the portion corresponding to the removed portion, and the same effect can be obtained.

[Embodiment 10] FIG. 10 is a schematic cross-sectional view showing another embodiment of a pair of high electric resistance electrode portions according to the present invention, in which 101 is a substrate, 102a, 102a ', 102.
Reference numerals b and 102b 'are thin film electrodes, and 103 is a microgap. In the figure, the electrode portion 10 having high electrical resistance
The electrode portions 102a and 102b having low electrical resistances 2a 'and 102b' are thin films made of the same material, and the electrode portions having high electrical resistance are those obtained by thinning the thin film of the portions by etching to increase the resistance. is there. The gist of the present invention is also achieved by such a configuration.

[Advantages of the Invention] The surge absorbing element of the present invention is a surface-mount type surge absorbing element having no lead wire, and is a large-scale production when mounted on a printed circuit board, as compared with a conventional surge absorbing element having two lead wires. Not only is it possible to improve the performance, but also to improve the heat dissipation that occurs when a large current surge is applied, and to prevent the discharge current from concentrating in the microgap part. It is possible to provide a surge absorbing element having an improved element life. Further, it is difficult to automate the arrangement of the lead wires that are more easily deformed, the cylindrical electrode portion that is cheap to roll, the cap, the glass tube, etc., and to handle them, which is a major obstacle to cost reduction. However, according to the present invention, it is possible to form electrodes on a large number of devices at the same time by a thick film or thin film forming technique using a multi-chamber substrate, and the mutual positional relationship of the devices on the multi-chamber substrate is accurate. , When the cap or lid is attached, the parts can be easily aligned by a simple jig, automation is facilitated, productivity is improved, and cost is reduced accordingly.

[Brief description of drawings]

FIG. 1 is a schematic sectional view of a surge absorber according to the prior art,
In the figure, 1a and 1b are a pair of electrodes, 2 is a microgap,
5 is a glass tube.

FIG. 2 is a first embodiment of a surge absorbing element according to the present invention,
A diagram is a schematic sectional view and B diagram is a plan view, in which 21 is a substrate, 22a and 22b are a pair of electrodes, 23 is a microgap, 24 is a glass film, 25 is a cap, 26 is a sealing material, 27a, 27b is an electrode terminal.

FIG. 3 is a schematic cross-sectional view of another embodiment according to the present invention, in which 31 is a substrate, 32a and 32b are a pair of electrodes,
33 is a micro gap, 34 is a glass film, 35 is a cap, 36 is a sealing material, and 37a and 37b are electrode terminals.

FIG. 4 is a schematic sectional view of another embodiment according to the present invention, in which 41 is a substrate, 42a and 42b are a pair of electrodes, and 4 is a pair of electrodes.
3 is a microgap, 44 is a glass film, 45 is a lid for sealing, and 48 is a sealing material.

FIG. 5 is another embodiment according to the present invention, FIG.
FIG. B is a schematic sectional view, in which 51 is a substrate, 52a, 52.
Reference numeral b is a pair of electrodes, and reference numerals 59a and 59b are conductive films for connecting conductors on the front and back surfaces of the substrate 51, respectively.

FIG. 6 is another embodiment according to the present invention, FIG.
B is a plan view, and 61 is a substrate 62a, 62 in the figure.
Reference numerals a ′, 62b and 62b ′ are electrodes, and 67a and 67b are electrode terminals.

FIG. 7 is a schematic cross-sectional view for stepwise explaining the production of a substrate with electrodes according to the present invention, in which 71 is a substrate, 72 is a resistance film formed by printing / baking, and 73 is a conductive film formed by printing / baking. It is a film, and 79 is a through hole.

FIG. 8 is a schematic cross-sectional view for explaining stepwise production of a substrate with electrodes according to the present invention, 81 is a substrate, 82 is a high resistance thin film, 83 is a thin film conductive film, and 89 is a through hole. .

FIG. 9 is a diagram showing another embodiment of the present invention.
Figures B and B are plan views, and C is a schematic cross-sectional view taken along line ab of FIG. In the figure, 91 is a substrate, 92a, 92a ', 92
b and 92b 'are electrodes, 93 is a microgap,
Further, 100 and 100 'are electrode removal parts.

FIG. 10 is a schematic cross-sectional view showing another embodiment according to the present invention, in which 101 is a substrate and 102a, 102.
Reference numerals a ′, 102b, and 102b ′ are electrodes, and 103 is a microgap.

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[Procedure amendment]

[Submission date] September 26, 1996

[Procedure amendment 1]

[Document name to be amended] Statement

[Correction target item name] Brief description of drawings

[Correction method] Change

[Correction contents]

[Brief description of drawings]

FIG. 1 is a schematic sectional view of a surge absorber according to the prior art,
In the figure, 1a and 1b are a pair of electrodes, 2 is a microgap,
5 is a glass tube.

FIG. 2A is a schematic sectional view showing an embodiment of a surge absorbing element according to the present invention, in which 21 is a substrate, 22a and 22b.
Is a pair of electrodes, 23 is a microgap, 25 is a cap, 26 is a sealing agent, and 27a and 27b are electrode terminals.

FIG. 2B is a schematic plan view of a substrate showing an embodiment of a surge absorber according to the present invention, in which 22a and 22b are a pair of electrodes, 23 is a microgap, 25 is a cap, and 2 is a cap.
7a and 27b are electrode terminals.

FIG. 3 is a schematic sectional view of another embodiment according to the present invention, in which 31 is a substrate, 32a and 32b are a pair of electrodes, and 3 is a pair of electrodes.
3 is a microgap, 34a and 34b are glass films, 3
5 is a cap, 36 is a sealing agent, and 37a and 37b are electrode terminals.

FIG. 4 is a schematic sectional view of another embodiment according to the present invention, in which 41 is a substrate, 42a and 42b are a pair of electrodes, and 4 is a pair of electrodes.
3 is a microgap, 44 is a glass film, 45 is a lid for sealing, and 48 is a sealing agent.

5A is a schematic plan view showing another embodiment according to the present invention, in which 51 is a substrate, 52a and 52b are a pair of electrodes, and 59a and 59b are conductors for connecting conductors on the front and back surfaces of the substrate 51, respectively. It is a film.

FIG. 5B is a schematic sectional view taken along the line ab in FIG. 5A of the embodiment according to the present invention, in which 51 is a substrate, 52a, 52.
Reference numeral b is a pair of electrodes, and reference numerals 59a and 59b are conductive films for connecting conductors on the front and back surfaces of the substrate 51, respectively.

FIG. 6A is a schematic sectional view showing another embodiment according to the present invention, in which 61 is a substrate, and 62a, 62a ′, 62b and 6 are shown.
2b 'is an electrode, and 67a and 67b are electrode terminals.

[Fig. 6B] Fig. 6B is a schematic plan view of another embodiment of the present invention, Fig. 6A, in which 62a, 62a ', 62b and 62b' are electrodes and 67a and 67b are electrode terminals.

[Fig. 7A] Fig. 7A is a schematic cross-sectional view for explaining step by step the production of a substrate with electrodes according to the present invention.
Processing progresses step by step with Figure C. In the figure, 71 is a substrate, 7
Reference numeral 2 is a resistance film formed by printing and firing, and 79 is a through hole.

[FIG. 7B] FIG. 7B is a schematic cross-sectional view for explaining stepwise the production of the substrate with electrodes according to the present invention, which is the step following FIG. 7A. In the figure, 71 is a substrate, 72 is a resistance film formed by printing and baking, 72a and 72b are conductive films formed by printing and baking, and 79 is a through hole.

[FIG. 7C] FIG. 7C is a schematic cross-sectional view for explaining stepwise the production of the substrate with electrodes according to the present invention, which is the step following FIG. 7B. In the figure, 71 is a substrate, 72 is a resistive film formed by printing / firing, 72a and 72b are conductive films formed by printing / firing, 73 is a microgap, and 72a ′, 72
Reference numeral b'denotes a pair of electrodes formed by a resistance film separated by a gap. 79 is a through hole.

[Fig. 8A] Fig. 8A is a schematic sectional view for explaining step by step the production of another substrate with electrodes according to the present invention. Fig. 8A → Fig. 8B →
Processing proceeds with FIG. 8C. Reference numeral 81 is a substrate, 82 is a high resistance thin film, and 89 is a through hole.

FIG. 8B is a schematic cross-sectional view for explaining step-wise the production of another substrate with electrodes according to the present invention, which is a step following FIG. 8A. 81 is a substrate, 82a 'and 82b' are a pair of electrodes made of a high resistance thin film, 83 is a microgap,
9 is a through hole.

[Fig. 8C] Fig. 8C is a schematic cross-sectional view for explaining stepwise the production of another substrate with electrodes according to the present invention, which is the stage following Fig. 8B. 81 is a substrate, 82a 'and 82b' are a pair of electrodes made of a high resistance thin film, 83 is a microgap,
Reference numerals 7a and 87b denote thick-film conductive films formed on both surfaces of the substrate, penetrating the through holes 89.

9A is a schematic plan view showing another embodiment according to the present invention, in which 92a, 92a ', 92b and 92 are shown.
b ′ is an electrode, 93 is a microgap, and 10
Reference numeral 0 is a removed portion of the electrode.

FIG. 9B is a schematic plan view showing another embodiment according to the present invention, in which the shape of the removed portion of the electrode is different from that in FIG. 9A. In the figure, 92a, 92a ', 92b, 92b'
Is an electrode, 93 is a microgap, and 100 '
Is a removal part of the electrode.

FIG. 9C shows an embodiment according to the present invention, and embodiment 9A
FIG. 9 is a schematic cross-sectional view taken along the line a-b of FIG.
Is a substrate, 92a, 92a ', 92b and 92b' are electrodes, 93 is a microgap, and 100 'is an electrode removal part.

FIG. 10 is a schematic cross-sectional view showing another embodiment according to the present invention, in which 101 is a substrate and 102a, 102.
Reference numerals a ′, 102b, and 102b ′ are electrodes, and 103 is a microgap.

Claims (1)

[Claims] 1. An electrode portion, which is electrically insulated from each other on the same plane of a substrate, is arranged so as to form a microgap or a gap, and has a high electric resistance in the vicinity of the microgap or the gap. A pair of electrodes consisting of an electrode portion having a relatively low electric resistance communicating with the electrodes or terminals, an electrode portion having a high electric resistance around the microgap or the gap and the gap, and a part of the electrode portion having a relatively low electric resistance. A microgap or a gap type surge absorbing element, comprising: an airtight cap or a lid for covering the flat surface of the substrate; and a pair of electrodes provided near both end faces of the substrate.