JPH07312409A - Surge absorbing structure, surge absorbing element, and connector and circuit device using the same - Google Patents

Abstract

PURPOSE:To provide a surge absorbing structure which can effectively use gas discharge without adopting a complicated structure like a conventional discharge tube. CONSTITUTION:A porous layer 1 which is formed by using non-conductive material so as to make many empty holes is interposed between a pair of electrodes arranged at specified intervals. Both of the electrodes are electrically connected by gas discharge which is generated through the empty holes 3. Thereby sourge is absorbed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a technique for protecting electronic circuits by absorbing surges caused by static electricity.

[0002]

2. Description of the Related Art For surge protection of an electronic circuit, a structure by gas discharge, that is, a phenomenon in which a minute discharge gap is provided between a pair of electrodes to cause conduction by dielectric breakdown of a gas layer in the discharge gap is utilized. The structure is known.

Generally, the discharge voltage in gas discharge is a function of the product PL of the gas pressure P mediating the discharge and the width L of the discharge gap, and when the width of the discharge gap is above a certain level, the discharge voltage becomes the width of this discharge gap. Rise accordingly (Paschen's law). In the case of air of 1 atm, the minimum discharge voltage is 7.5 μm between the electrodes, and the voltage is about 330 V, which is a voltage that can be used for surge protection of general electronic circuits. In other words, it is theoretically possible to achieve surge protection by a structure in which a discharge gap formed by an air layer having a constant width is provided between both electrodes. However, in reality, it is almost impossible to always set a very narrow discharge gap of 7.5 μ between both electrodes.

Therefore, when using gas discharge for surge protection, a structure using a discharge tube has been conventionally used. This discharge tube has an airtight structure that is filled with a discharge gas to reduce the minimum breakdown voltage so that a practical discharge voltage can be obtained even in a discharge gap of about several tens of μm (for example, JP-A-5-268725 and JP-A-5-226060). Therefore, the surge absorbing element having the discharge tube structure has a complicated structure, has no degree of freedom in its shape, and has a large size, and is inevitably a single type. as a result,
It is necessary to use an element for each individual signal line to be protected, which leads to an increase in the size and complexity of the circuit device and a significant cost increase. In addition, it requires a relatively large mounting space, and in particular, when it is mounted on the connector in order to protect against surges at the connector stage, the mounting is very difficult in terms of space ... There are many restrictions on use.

[0005]

The present invention has been made against such a background, and provides a surge absorbing structure capable of effectively utilizing gas discharge without depending on a complicated structure such as a conventional discharge tube. It aims at providing the surge absorption element used for this, and also the purpose of providing the connector and circuit device which used these.

[0006]

In a surge absorbing structure according to the present invention, a porous layer formed of a non-conductive material having a large number of holes is interposed between a pair of electrodes opposed to each other at a predetermined interval. Then, both electrodes are conducted by the gas discharge generated through the holes in the porous layer to absorb the surge.

A schematic representation of this surge absorbing structure is shown in FIG. That is, the porous layer 1 includes a pair of electrodes 2a,
2b are formed in contact with each other, and the holes 3 therein provide individually independent air layers for gas discharge,
The discharge in the holes 3 causes conduction. The discharge in the holes 3 is accompanied by a creeping discharge along the wall surface 3w of the holes 3 and the like, so that the discharge voltage is greatly reduced as compared with the case where there is a discharge gap. That is, by interposing the porous layer, the discharge voltage of the gas discharge in the air can be lowered, and thus the surge absorption range can be expanded. With this surge absorbing structure,
As described above, since the discharge gap can be set by the porous layer whose thickness can be easily controlled, the setting can be performed with high accuracy and stability.

The porous layer in such a surge absorbing structure is formed by, for example, a method of depositing a SiO ₂ layer on the surface of a metal material for one electrode by an electrolytic deposition method or PVD such as sputtering or ion plating. Method for growing a thin layer of a non-conductive material on the surface of a metal material for an electrode, an aluminum material is used as one electrode, and a film of γ-Al ₂ O ₃ is grown on the surface of this aluminum material by an anodic oxidation method. Method, a method of attaching particles having a diameter corresponding to the intended thickness of the porous layer to one electrode with an adhesive, and a method of forming using a sheet having a large number of minute through holes formed by laser processing, etc. It can be formed in a wide variety of ways. The porous layer formed of these has a large number of through holes having a diameter size of the order of μm, and generally has a size of several to several tens of μm.
It is formed with a thickness of, but the thickness can be easily controlled.

Since the present surge absorbing structure provides conduction by the discharge through the pores in the porous layer as described above, basically the pores in the porous layer are in a penetrating state between both electrodes. However, as shown in FIG. 2, using the conductive material 4 to close the ends of the holes 3 to an appropriate depth is substantially the same as the state of penetrating between both electrodes. Therefore, the conduction principle of the surge absorbing structure can be similarly used. When a material having a high melting resistance such as carbon is used as the conductive material filling the ends of the holes, melting of the electrodes due to discharge can be suppressed, and more preferable conditions can be obtained.

The filling of the pores with such a conductive material is
When the porous layer is formed by the above-mentioned film of γ-Al ₂ O ₃ , it can be carried out by utilizing the sealing treatment with high-pressure steam used in so-called alumite treatment. That is, when the film of γ-Al ₂ O ₃ is sealed with high-pressure steam, γ-Al ₂ O ₃ · H ₂ O grows from the inner wall surface of the hole toward the inside at the upper end of the hole. As a result, it is possible to perform the filling of the pores by a conductive _{γ-Al 2 O 3 · H} 2 O.

The porous layer in the surge absorbing structure of the present invention may be formed using a material having a non-linear resistance characteristic such as SiC, in addition to an insulating material in a narrow sense. When such a non-linear resistance characteristic material is used, the solid part around the hole functions as a primary surge absorber due to its non-linear resistance property, and when the current exceeds the allowable amount and the resistance of the solid part increases. Secondary surge absorption can be performed by the discharge in the holes. That is, the surge protection function can be further improved by combining the nonlinear resistance characteristic in the solid portion of the porous layer and the discharge in the holes.

The surge absorbing element used in the surge absorbing structure as described above can be formed by adhering the porous layer to one electrode by the various methods as described above, and if necessary, the other The electrode may be attached to the other surface of the porous layer. Therefore, in particular, when a porous layer is attached to one of the electrodes to form a surge absorbing element, for example, a thin metal sheet is used for the electrode, and the porous layer is formed on the surface thereof and then cut into a desired size and shape. It is possible to form. Such a surge absorbing element has an extremely simple structure, is excellent in workability, and has a large degree of freedom in shape and size.
For example, it can be easily used by collectively protecting a plurality of signal lines by forming it into an elongated strip shape, and since it is possible to give great flexibility, it is excellent in wearability. It is also possible to form a porous layer on the connector terminal itself, which will be one of the electrodes, and in this way the connector terminal itself can be used as an element of the surge absorbing element, and mounting on the connector is much easier. Can be converted.

To use the above surge absorbing structure or surge absorbing element in a connector, a porous layer is formed on the terminal of the connector as described above so that the terminal of the connector itself serves as an element of the surge absorbing element. In addition, it is of course possible to incorporate a separately formed surge absorbing element, and it is also possible to incorporate it into the ground electrode of the connector by forming a porous layer as in the case of the terminal. Regarding the formation of the porous layer on the ground electrode, a structure is possible in which the porous layer is formed on both surfaces of the ground electrode and the porous layer on each surface is brought into contact with the terminal as the other electrode. In this case, two sets of surge absorbing structures are formed with the ground electrode commonly used as one of the pair of electrodes.

When the surge absorbing structure or the surge absorbing element is used in a circuit device such as a printed circuit, a surge absorbing element formed separately may be incorporated as in the case of the connector, or the circuit device may be incorporated. Alternatively, the porous layer may be directly attached and formed on the ground electrode. In the latter case, as in the case of the connector, the ground electrode can be shared by the two sets of surge absorbing structures.

[0015]

EXAMPLES Examples of the present invention will be described below. The present example is an example in which an aluminum material is used as one of the electrodes, and a SiO ₂ layer is deposited on the surface thereof by electrolytic deposition to form a porous layer. The aluminum material used is a sheet with a thickness of 300 μm, and is made of Si with a porosity of around 40%.
An O ₂ film was formed with a thickness of 10μ. The discharge voltage of the surge absorbing element thus obtained was about 200 V, and the voltage clamp speed was about 5 nanoseconds. Further, the surge absorbing element according to this example has high flexibility, can be easily bent, and is sufficiently resistant to bending of 90 ° or more.

The surge absorbing element 10 shown in FIG. 3 is an example in which the surge absorbing element 10 produced under the above conditions is mounted on a substrate, and a fixing leg portion 12 is extended from a base electrode 11 serving as one electrode. There is. To mount this on the substrate, as shown in FIG. 4, the porous layer 13 is brought into contact with the signal line L of the substrate B, which is the other electrode, and is fixed to the substrate B by the leg portions 12.

FIG. 5 shows an example of a modular connector 20 incorporating a surge absorbing structure according to the present invention, in which a porous layer 23 is interposed between a shell member 21 as one electrode and a terminal 22 as the other electrode. It is made to have a structure. Such a structure can be provided by partially forming the porous layer 23 integrally with the shell member 21 or by integrally forming the porous layer 23 with the terminal 22. It can also be formed by incorporating a surge absorbing element formed separately from the member 21 and the terminal 22.

[0018]

As described above, according to the surge absorbing structure of the present invention, the porous layer is interposed between the pair of electrodes,
Since the structure is such that gas discharge is generated through a large number of pores in this porous layer, the structure of the surge absorbing element can be greatly simplified, and the flexibility and flexibility of the shape and size of the surge absorbing element can be increased. It is also possible to provide the surge absorber with the capability. As a result,
According to the surge absorbing structure and the element of the present invention, it is possible to collectively protect a plurality of signal lines, and it is possible to easily mount the connector on the board as well as on the board. The range can be expanded.

[Brief description of drawings]

FIG. 1 is a schematic diagram of a surge absorbing structure according to the present invention.

FIG. 2 is a schematic view of another example of the surge absorbing structure according to the present invention.

FIG. 3 is a perspective view of a surge absorber according to an embodiment of the present invention.

FIG. 4 is a cross-sectional view showing a state in which the surge absorber of FIG. 3 is mounted on a substrate.

FIG. 5 is a cross-sectional view of a modular connector using a surge absorbing structure according to the present invention.

[Explanation of symbols]

 1 Porous Layer 2a Electrode 2b Electrode 3 Void

Claims (4)

[Claims] 1. A gas generated through the holes in the porous layer, wherein a porous layer formed of a non-conductive material having a large number of holes is interposed between a pair of electrodes opposed to each other at a predetermined interval. Surge absorbing structure that conducts both electrodes by discharging and absorbs surge. 2. The surge absorbing element used in the surge absorbing structure according to claim 1, wherein a porous layer is adhered and formed on one electrode. 3. A connector using the surge absorbing structure according to claim 1 or the surge absorbing element according to claim 2. 4. A circuit device using the surge absorbing structure according to claim 1 or the surge absorbing element according to claim 2.