JPH10134933A - Surge absorber - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the reliability, and while to lower the cost by concentrically forming all of a first and a second electrodes, a conductive film and a gap on an insulating board, and forming a part of the conductive film, which is formed in a back surface of the board sealed with a sealing cap material, with a fuse. SOLUTION: Inside a through hole of an aluminum board 1 is filled with a conductor, and a surface of the aluminum board 1 is formed with a conductive film 10, and a back surface thereof is formed with a conductive film 21 and a fuse 19. The fuse 19 is formed by adhering a Pn alloy film by deposition or the like. The surface of the aluminum board 1 is formed with a conductive film, and a circular micro gap at about 50μm of width is formed, and the conductive film is formed into a desirable circle. A cap 6 is covered on the micro gap, a first and a second electrodes, and welded thereto so as to seal them in Ar gas. With this structure, the fuse 19 can be arranged between a lead 14 and a lead 20.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a surge absorber having an overvoltage / overcurrent protection function.

[0002]

2. Description of the Related Art Conventionally, there has been known a surge absorber which is used for protecting an electronic device and absorbs a surge voltage applied to the electronic device. For example,
In Japanese Patent No. 57918, a conductive ceramic thin film is formed on the surface of a cylindrical insulating material, and a micro gap is formed in a circumferential direction so as to divide the conductive ceramic thin film. A surge absorber having a structure in which the charged state is sealed in a cylindrical glass is disclosed. In addition, Japanese Utility Model Laid-Open No. 49-80351 proposes a surge absorber in which a spire-shaped electrode having a sharp point is formed on a flat insulating substrate with a micro gap therebetween.

[0003]

In some cases, a surge absorber for absorbing surges as described above is used in combination with a fuse for preventing overvoltage and overcurrent. In such a case, a fuse must be attached separately from the surge absorber, which causes problems such as an increase in mounting area and mounting cost. JP-A-3-230485 proposes a structure in which a linear fuse is bridged so as to be in contact with a cylindrical surge absorbing element, and the surge absorbing element is sealed together with the fuse. In this case, an increase in the mounting area can be avoided because the fuse is incorporated in one surge absorber, but a problem arises in that the cost of the surge absorber itself increases because a fuse manufactured as a separate component is incorporated.

[0004] In view of the above circumstances, it is an object of the present invention to provide a surge absorber incorporating a fuse for preventing overvoltage and overcurrent and reducing the cost.

[0005]

According to a first aspect of the present invention, there is provided a surge absorber having a plate-like insulating substrate and an annular gap formed on a surface of the insulating substrate, the disc being concentric with the gap. A first electrode disposed at the center of the conductive film, and a first electrode disposed at a peripheral portion of the conductive film.
An airtight hermetic cap that seals the first electrode and the gap in a state in which a predetermined gas is filled therein in cooperation with an insulating second substrate and an annular second electrode concentric with the gap; And a first material disposed outside the hermetic crown material.
A first terminal electrically connected to the second electrode, a second terminal electrically connected to the second electrode, disposed outside the hermetic capping material, and a back surface of the insulating substrate Is connected to one of the first terminal and the second terminal via a film-shaped electrical connection path formed at least in part by a film-shaped fuse. And a third terminal disposed outside the hermetic crown material.

Here, in the surge absorber according to the present invention, the first electrode and the first terminal are formed on a portion of the insulating substrate on which the first electrode is arranged, and the insulating substrate is formed on the insulating substrate. While penetrating between the front and back of
A through-hole filled with a conductor electrically connected to the first electrode and a conductor in the through-hole and a first terminal formed in a film on the back surface of the insulating substrate are electrically connected. The conductive film may be electrically connected to the conductive film to be connected, and the conductive film and the third terminal may be electrically connected to each other by a fuse formed in a film shape on the back surface of the insulating substrate. Alternatively, the first electrode and the first terminal are formed in a portion of the insulating substrate where the first electrode is arranged, and the inside is filled with a conductor electrically connected to the first electrode. And electrically connected to a conductor layer formed inside the insulating substrate and electrically connected to the first terminal and electrically connected to a conductor inside the via hole at the bottom of the via hole. Of the first terminal and the second terminal Square terminal and the third terminal is a fuse formed in a film shape on the back surface of the insulating substrate may be composed are electrically connected.

In the surge absorber according to the present invention, when the surface on which the fuse is formed needs to be directed upward, as shown in an embodiment to be described later, the surface on which the conductive film is formed is directed downward and the leads are attached to the terminals. Thereby, the surface on which the fuse is formed can be directed upward. ADVANTAGE OF THE INVENTION The surge absorber of this invention can form a film-shaped fuse on an insulating board | substrate by vapor deposition method, automation is easy, and cost reduction is possible.

In the surge absorber according to the present invention, since the fuse for preventing overvoltage and overcurrent is formed on the back surface of the insulating substrate relative to the surface on which the conductive film is formed, the surge absorber is provided with a fuse for preventing overvoltage and overcurrent. There is no problem such as an increase in the size of the element and an increase in the mounting area due to the attachment of the fuse. In the surge absorber of the present invention,
Since the film-shaped fuse is formed on the insulating substrate, the possibility of disconnection of the fuse due to mechanical vibration is extremely low, the reliability is high, and the film-shaped fuse is formed on the insulating substrate. Therefore, when the surge absorber is overheated, the heat generated by the overheating is easily transmitted to the fuse, and the responsiveness is good.

Since the basic structure and principle of the surge absorber of the present invention are the same as those disclosed in Japanese Patent Publication No. 63-57918, an excellent surge absorber provided in the surge absorber disclosed therein. Absorption characteristics and high reliability are maintained as they are, and furthermore, the surge absorber of the present invention incorporates a fuse for preventing overvoltage and overcurrent, so that overheating can be prevented.

[0010]

Embodiments of the present invention will be described below. 1 to 6 show a first embodiment of a surge absorber of the present invention, respectively, a perspective view showing the internal structure by partially breaking the cap, a plan view showing the cap transparently, and the cap facing downward. Perspective view, arrow A in FIG.
-A, a cross-sectional view along arrow AA 'in FIG. 3,
And an equivalent circuit diagram. However, FIGS. 1 and 2 show a state before the leads 14, 15, and 20 are attached.

A through hole 11 (see FIG. 4) is formed in a flat alumina substrate 1 as an insulating substrate, and a conductor is filled in the through hole 11. On the back surface, a conductive film 21 is provided.
A fuse 19 is formed. The fuse 19 is formed by depositing a Pb alloy film by a vapor deposition method. Further, a conductor film 5 is formed on the surface of the alumina substrate 1 as T
After depositing iN by sputtering, a circular microgap 3 having a width of about 50 μm is formed by photoetching, and the conductive film 5 is formed into a desired circular shape.
The first electrode 2 and the second electrode 4 are attached concentrically with the micro gap 3 so as to be in contact with the conductive film 5. Further, the first electrode 2, the micro gap 3, and the second electrode 4 are sealed in an Ar gas by welding a cap 6 made of alumina ceramics with frit glass 7, and furthermore, FIGS. Lead 14, 1 of the shape shown
Attach 5, 20. In the present embodiment, the leads 14,
Reference numeral 15 corresponds to a first terminal and a second terminal according to the present invention, and the present embodiment includes a third terminal (lead 20) connected to the first electrode 2 by a fuse 19. .

As a result, as shown in FIG.
Between the first electrode 2 and the second electrode 4
And the surge absorbing element sandwiched between
A surge absorber having an equivalent circuit in which fuses 19 are arranged between the lead 4 and the lead 20 is realized. According to this surge absorber, a highly reliable fuse is incorporated, an increase in mounting area is avoided, and cost reduction is realized.

FIGS. 7 to 9 show a second embodiment of the surge absorber according to the present invention. FIG. 7 is a perspective view showing a state in which a gap is directed downward, FIG. FIG. 6 is a partial view of a cross section taken along arrow BB ′ of No. 6; In the second embodiment, a via hole 1 is used as an insulating substrate.
6 and the conductor layer 17 are formed on the low-temperature fired multilayer substrate 23, and the surface of the substrate 23 has the first electrode 2, the conductor film 5, the micro gap 3, the second
The electrode 4, the conductor film 10, the cap 6 and the like are formed or arranged, and a thin-film fuse 19 is formed on the back surface of the substrate 23 over substantially the entire length of the meridian connecting the lead 14 and the lead 20. The connection between the first electrode 2 and the lead 14 is performed by exposing the conductor layer 17 inside the substrate 23 to the side surface of the substrate 23 and forming the conductor film 22 also on the side surface of the substrate 23 as shown in FIG. Performed by

Also in the second embodiment, a surge absorber incorporating a highly reliable fuse having a circuit configuration represented by the same equivalent circuit as the equivalent circuit shown in FIG. 6 is realized, and the mounting area is reduced. And cost reduction is achieved.

[0015]

As described above, according to the present invention,
A surge absorber incorporating a highly reliable fuse and reducing the cost is realized.

[Brief description of the drawings]

FIG. 1 is a perspective view showing an internal structure of a surge absorber according to a first embodiment of the present invention with a cap partially cut away.

FIG. 2 is a plan view of the surge absorber according to the first embodiment of the present invention as seen through a cap.

FIG. 3 is a perspective view showing the surge absorber according to the first embodiment of the present invention with the cap facing downward.

FIG. 4 is a cross-sectional view of the surge absorber according to the first embodiment of the present invention, taken along arrow AA in FIG. 3;

FIG. 5 is a cross-sectional view of the surge absorber according to the first embodiment of the present invention, taken along the line AA ′ in FIG. 3;

FIG. 6 is an equivalent circuit diagram of the first embodiment of the surge absorber according to the present invention.

FIG. 7 is a perspective view of a second embodiment of the surge absorber according to the present invention, with a cap directed downward.

FIG. 8 is a cross-sectional view of the second embodiment of the surge absorber according to the present invention, taken along arrow BB in FIG. 7;

FIG. 9 is a partial view of a cross section taken along arrow BB ′ of FIG. 7 in a second embodiment of the surge absorber according to the present invention.

[Explanation of symbols]

 Reference Signs List 1 alumina substrate 2 electrode 3 micro gap 4 electrode 5 conductor film 6 cap 7 frit glass 10 conductor film 14, 15 lead 16 via hole 17 conductor layer 19 fuse 20 lead 21 conductive film 22 conductor film

Claims (3)

[Claims] 1. A flat insulating substrate, a conductive film having an annular gap formed on the surface of the insulating substrate and formed in a disc shape concentric with the gap, and a central portion of the conductive film A first electrode disposed on the periphery of the conductive film, an annular second electrode concentric with the gap, and the first electrode in cooperation with the insulating substrate. And an airtight crown material that seals the gap in a state where a predetermined gas is filled therein, and electrically connected to the first electrode disposed outside the airtight crown material. A first terminal, a second terminal disposed outside the hermetic capping member and electrically connected to the second electrode, and at least a second terminal formed on a back surface of the insulating substrate. Via a film-like electrical connection path partially formed by a film-like fuse, Is connected to one terminal of the first terminal and the second terminal comprising, the airtightness third terminal and the surge absorber characterized by comprising a disposed outside of the crown member. 2. The method according to claim 1, wherein the first electrode and the first terminal penetrate between a front surface and a rear surface of the insulating substrate, the first electrode and the first terminal being formed in a portion of the insulating substrate where the first electrode is arranged. ,
A through-hole in which a conductor electrically connected to the first electrode is filled, and a conductor in the through-hole formed on the back surface of the insulating substrate and the first terminal are formed. Electrically connected by a conductive film to be electrically connected, wherein the conductive film and the third terminal are electrically connected by a fuse formed in a film shape on the back surface of the insulating substrate. The surge absorber according to claim 1, wherein: 3. The first electrode and the first terminal are formed in a portion of the insulating substrate on which the first electrode is arranged. The first electrode and the first terminal are electrically connected to the first electrode. A via hole filled with a connected conductor; and a via hole formed inside the insulating substrate and electrically connected to the first terminal, and electrically connected to a conductor inside the via hole at a bottom of the via hole. One of the first terminal and the second terminal and the third terminal are formed in a film shape on the back surface of the insulating substrate. 2. The surge absorber according to claim 1, wherein the surge absorber is electrically connected by a fuse.