JPH06150829A - Surge absorbing element - Google Patents

Abstract

PURPOSE:To enable an overvoltage to be absorbed by a surge absorbing element by forming a slight clearance between a surge absorbing portion and an electrode, and.sealing gas between the electrodes by insulative coating member. CONSTITUTION:A cylindrical ceramic (insulator) 1 has a large center and both narrow ends. A carbon alloy or metal coating film 2 having a surge absorbing characteristic is stuck to the large center portion, thus obtaining a surge absorbing portion. Terminals 4 are jointed to the ceramic portion at the narrow ends via metal caps 3, thereby providing electrodes. A slight clearance 7 is formed between the metal cap 3 and the surge absorbing portion. Sealing gas is sealed between the electrodes with the terminals 4 fixed thereto by an insulative coating member by utilizing the surface nearest the electrode of the carbon alloy in the broad center portion and the cross section of the metal cap 3 nearest the electrode. Consequently, a surge voltage is absorbed by the surge absorbing portion so that durability of a surge absorbing element is enhanced.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a surge absorbing element which absorbs an overvoltage applied between electrodes of a semiconductor element or the like.

[0002]

2. Description of the Related Art Conventionally, this type of film type surge absorbing element has a cylindrical ceramic film coated with a metal oxide or the like, and a metal cap with terminals bonded to both ends of the film, and the center of the film coated with the metal oxide or the like. The portion was divided by forming a processing mark in a circular shape by a laser light or the like, and the cross section of the film made of metal oxide or the like was used as a discharge gap. This method is around 1 micron (μm) even for metal oxides, which are said to have a thick coating of metal oxides, and 0.2 micron (μm) for metal thin films formed by sputter deposition.
m) Since only a very small volume is obtained, the deterioration due to the heat generated during discharge is remarkable and there is a problem in durability as a surge absorbing element. Further, even if the ceramic substrate such as forsterite, steatite or the like having a poor thermal conductivity is used and the alumina porcelain having a relatively good thermal conductivity is used, the thermal conductivity is 17 to 21 W / mK. The poor thermal conductivity of these ceramics has a drawback of promoting the progress of deterioration due to discharge heat generation due to the film thickness of the metal oxide or the like (since the film thickness is thin).

[0003]

[Problems to be Solved by the Invention]

1. A surface with a small discharge gap called cutting of a film by a metal oxide attached to the surface of a cylindrical ceramic, and
The cross section of one metal cap on the opposite side was thickened to make a durable product with less wear. Improve the durability of the surge absorbing element by making the other surface a large area by using the surface of the film. 2. By using zirconium oxide porcelain for the ceramic that serves as the substrate of the surge absorbing element, the purpose is to improve the heat generation due to discharge generated during discharge and the temperature cycle characteristics applied to the substrate when the discharge is stopped.

[0004]

[Means for Solving the Problems]

1. The present invention is a surge absorbing portion by adhering a carbon alloy or a metal film having a surge absorbing characteristic to the thick central portion of a cylindrical ceramic having a thick central portion and narrow both ends,
A carbon alloy or metal adhered to the thick center part is formed by joining terminals to the metal caps on the thin ceramic parts at both ends to form an electrode part and providing a slight space between the metal cap and the surge absorbing part. The surface of the film closest to the electrode portion and the cross section of the metal cap closest to the electrode portion are used to discharge, and the surge absorbing portion absorbs the surge voltage. 2. In Claim 1, a carbon alloy or a metal film having a surge absorbing property is adhered to a cylindrical ceramic having a thick center portion and narrow both ends, metal caps are attached to the narrow portions at both ends, and the metal cap is further attached. Join the terminals to make a surge absorbing element. The inner surface of the metal cap of the surge absorbing element and the carbon alloy or the metal film immediately below the inner end surface of the metal cap are completely removed from the ceramic along the circumference by using a laser light processing machine. The cap portion is divided into the electrode portion and the central carbon alloy or metal film portion is divided into the surge absorbing portion, and the inner end surface of the metal cap, that is, the end surface of the metal cap closest to the surge absorbing portion and the carbon alloy closest to the metal cap or Electric discharge is made between the surfaces of the metal film, and the surge voltage is absorbed by the surge absorbing section.

[0005]

【Example】

1. Tin / antimony (Sn / Sb) is added to the thick center of a cylindrical alumina ceramic with a thick center and narrow ends.
A system alloy film is attached, and metal caps with terminals are joined to the thin alumina ceramic parts at both ends to form an electrode part, and a space of 0.1 to 0.5 mm is provided between the metal cap and the tin / antimony alloy film. And a surge absorbing element in which a terminal is attached between the both electrodes and argon gas is enclosed between the both electrodes by using an insulating coating material.

【The invention's effect】

In the conventional surge absorbing element, a film of conductive metal or metal oxide adheres to mullite porcelain, forsterite porcelain, alumina porcelain, steatite porcelain, etc. on an insulator (insulating columnar body), so However, there is a drawback that the thermal cycle easily causes a rupture phenomenon. Therefore, as an improvement over these drawbacks, thermal cycles, strong oxidizing zirconium in thermal shock - arm (ZrO ₂₎ a conductive metal to the ceramic cylindrical surface, or a metal oxide deposited was oxide zirconium - arm (ZrO ₂ ) A metal or alloy piece having a high corrosion resistance and high electric property is fixed to both ends of the ceramic to form an electrode, and thereafter, the conductive metal or metal oxide is formed into a film having a thickness of 0.1 μm to 30 μm and a width. A circular gap of 10 μm to 200 μm is engraved by laser trimming, and a linear gap wider than this microgap is engraved so as to intersect with this and divided into a plurality of parts, and each of these electrodes has a terminal. This is a structure in which an insulating coating material of a mixed gas of nitrogen gas and argon gas is enclosed between the both electrodes of the element to which is attached.

[Brief description of drawings]

FIG. 1 is a perspective view.

FIG. 2 is a development view.

FIG. 3 is a correlation diagram showing a microgap and a discharge start voltage.

[Explanation of symbols]

 1 Insulator 2 Metal Oxide 3 Metal Cap (Electrode) 4 Terminal 5 Lead Glass 6 Inert Gas 7 Micro Gap

Claims (8)

[Claims] 1. A cylindrical ceramic having a thick central portion and narrow both ends, a carbon alloy or a metal film having a surge absorbing characteristic is adhered to the thick central portion to form a surge absorbing portion, and the thin ceramic portions at both ends are made of metal. The terminal is joined to the cap to form the electrode part, and by providing a slight space between the metal cap and the surge absorbing part, it is closest to the electrode part of the carbon alloy or metal film attached to the thick center part. A cross-section of the metal cap closest to the surface and the electrode portion is used, and a filling gas is sealed between the both electrodes of an element having terminals attached to the both electrodes by using an insulating coating material. Surge absorption element 2. The method according to claim 1, wherein a carbon alloy or a metal film having surge absorbing characteristics is adhered to a cylindrical ceramic having a thick center portion and narrow end portions, and a metal cap is attached to the narrow end portions. The surge absorbing element is mounted by attaching the metal cap and the terminal to the metal cap. By completely removing the carbon alloy or the metal film directly below the inner end surface of the metal cap and the inner end surface of the metal cap of the surge absorbing element from the ceramic along the circumference by using a processing machine such as laser light. The metal cap portion is divided into the electrode portion, the central carbon alloy or the metal film portion is divided into the surge absorbing portion, and the metal cap inner end surface, that is, the metal cap end surface closest to the surge absorbing portion and the carbon alloy closest to the metal cap are divided. Alternatively, the surge absorbing element is characterized in that the surge absorbing portion absorbs the surge voltage by discharging between the surfaces of the metal film. 3. The surge according to claim 1, wherein the conductive metal or metal oxide is one selected from the group consisting of tin oxide (SnO ₂ ), ruthenium oxide (RuO ₂ ), and the like. Absorption element. 4. The surge absorbing element according to claim 1, wherein the conductive metal is a carbon alloy film of carbon and a silicon compound. 5. The surge absorbing element according to claim 1, wherein the metal piece having high corrosion resistance and high electric conductivity is stainless steel or Kovar. 6. The insulator has a thermal conductivity of 70 to 200 W /
The surge absorbing element according to claim 1, which is an insulator of mK. 7. The insulator is alumina nitride (Al
The surge absorbing element according to claim 1, wherein the surge absorbing element is one selected from the group consisting of N ₂ ), and beryllium oxide (BeO ₂ ). 8. The surge absorbing element according to claim 1, wherein the surge absorbing element is a mixed gas composed of 90 to 99% of the enclosed gas N ₂ gas and 1 to 10% of argon gas.