JP2011103224A - Overvoltage protection component - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an overvoltage protection component that prevents discharge characteristics from deteriorating, with a discharge electrode having a reaction, such as oxidization. <P>SOLUTION: An overvoltage protection component 7 comprises an element body 1 produced by calcining a ceramic; a discharge hollow part 2 formed inside the element body 1; a first discharge electrode 3 and a second discharge electrode 4, which are formed at a distance from each other by the discharge hollow part 2; a first terminal electrode 5 and a second terminal electrode 6, which are formed outside the element body 1 and are electrically connected to the first discharge electrode 3 and the second discharge electrode 4, respectively; and the first discharge electrode 3 and the second discharge electrode 4 are made of gold, or a mixture of gold and resin. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to an overvoltage protection component that protects an electronic device from static electricity or surge.

  In recent years, downsizing and high performance of electronic devices are rapidly progressing, and accordingly, downsizing of electronic parts used in electronic devices is also progressing rapidly. However, with this miniaturization, electronic devices and electronic components are less resistant to overvoltages such as static electricity and surges, and overvoltage protection components are used as countermeasures. Overvoltage protection components are electrically connected in parallel with electronic components that are to be protected from overvoltages, and normally do not conduct electricity, but they conduct electricity when overvoltage is applied to prevent current from overvoltage from flowing to the electronic components. It is.

  As an example of such an overvoltage protection component, an element body obtained by laminating and firing ceramics, a discharge cavity part for discharging inside the element body, and the discharge cavity part facing each other in the plane direction There is an overvoltage protection component including a pair of discharged electrodes. The manufacturing method of laminating and firing ceramics in this way does not require management of adhesive application conditions and curing conditions compared to the conventional manufacturing method in which a discharge cavity is provided by bonding a lid to a substrate, and a large amount Suitable for production (see Patent Document 1).

Japanese Patent Laid-Open No. 1-102884

  The discharge electrode disclosed in Patent Document 1 fires an unfired ceramic in an atmosphere of an inert gas such as argon, and thereby fills the discharge cavity in the element body with an inert gas.

  However, the inventors of the present invention have found that the material contained in the unfired ceramic remains in the cavity during the firing of the ceramic. Then, the present inventors have found that the residue causes a reaction such as oxidation with copper constituting the discharge electrode due to repeated overvoltage at the time of use, and thereby the discharge characteristics may be deteriorated.

  The present invention solves the above-described conventional problems, and provides an overvoltage protection component that prevents discharge characteristics from deteriorating due to a reaction such as oxidation of a discharge electrode.

  In order to achieve the above object, the present invention has the following means.

  According to the first aspect of the present invention, there is provided an element body obtained by firing ceramic, a discharge cavity formed inside the element body, and a pair of the discharge cavity part spaced apart from each other. And a pair of terminal electrodes formed outside the element body and electrically connected to the pair of discharge electrodes, respectively, and the pair of discharge electrodes is gold or a mixture of gold and resin. It is a protective part.

  With this configuration, the invention described in claim 1 is based on the fact that the gold used for the discharge electrode reacts with the residue generated during the firing of the ceramic while using the method of firing the ceramic suitable for mass production to obtain the element body. Therefore, there is an effect that the deterioration of the discharge characteristics can be prevented.

  Gold is a chemically very stable substance and is known to be used in places where inconvenience occurs when oxidized. For this reason, it is widely used to use gold in a place in contact with the outside air, such as a technique of performing gold plating on the surface of an electrode such as a printed circuit board.

  On the other hand, the present invention is provided inside a ceramic body and is shielded from the outside air, so that a reaction such as oxidation can occur even in a discharge cavity that seems not to worry about oxidation. It is based on the new knowledge that there is sex.

  The invention described in claim 2 is particularly one in which rhodium is added to the discharge electrode. Here, when rhodium is not added, gold in the discharge electrode grows when firing the ceramic body, and when the gold grows, the surface of the discharge electrode is flattened and discharge is less likely to occur. This causes deterioration of the characteristics. On the other hand, since rhodium has an action of suppressing the growth of gold grains, the invention according to claim 2 can prevent the discharge electrode from being flattened by the growth of gold grains, and has good discharge characteristics. It has the effect of being able to do.

  In the invention according to claim 3, the terminal electrode is made of silver or silver and a resin, and an alloy part having an alloy of gold and silver is provided between the discharge electrode and the terminal electrode. is there.

  A discharge electrode containing gold and an alloy part containing an alloy of gold and silver have excellent adhesion and high connection reliability between them. Moreover, both the terminal electrode containing silver and the alloy part have excellent adhesion and high connection reliability. As can be understood from this, the invention according to claim 3 has an effect of being excellent in electrical connection reliability.

  As described above, the overvoltage protection component of the present invention has an effect of preventing the discharge characteristics from deteriorating due to a reaction such as oxidation of the discharge electrode by using gold for the discharge electrode.

Front sectional drawing of the overvoltage protection component in Embodiment 1 of this invention The figure which shows the manufacturing method of the same overvoltage protection component The figure which shows the manufacturing method of the same overvoltage protection component Front sectional view of the overvoltage protection component in Embodiment 3 of the present invention The figure which shows the manufacturing method of the same overvoltage protection component

(Embodiment 1)
Hereinafter, the first aspect of the present invention will be described in particular, using the first embodiment.

  FIG. 1 is a front sectional view of an overvoltage protection component according to Embodiment 1 of the present invention.

  The element body 1 is made of an insulator, and has an outer shape that is a substantially rectangular parallelepiped shape and has a cavity inside. The element body 1 is required not to be damaged even if electric discharge occurs inside, and is made of a ceramic excellent in heat resistance and thermal shock.

  The discharge cavity 2 is a substantially rectangular parallelepiped cavity formed inside the element body 1, and discharge is generated in the cavity when an overvoltage is applied.

  The first discharge electrode 3 is provided inside the element body 1, and a part of the first discharge electrode 3 is exposed to the discharge cavity 2. The second discharge electrode 4 is also provided inside the element body 1, and a part of the second discharge electrode 4 is exposed to the discharge cavity 2. The first discharge electrode 3 and the second discharge electrode 4 are formed on the bottom surface of the inner wall of the discharge cavity portion 2 and on the ceiling surface facing the other, and are opposed to each other in the surface direction. The first discharge electrode 3 and the second discharge electrode 4 use gold.

  The first terminal electrode 5 is formed outside the element body 1 and is electrically connected to the first discharge electrode 3, and the second terminal electrode 6 is formed outside the element body 1, It is electrically connected to the discharge electrode 4.

  The overvoltage protection component 7 has the above configuration.

  Next, a manufacturing method is demonstrated using FIG. 2 and FIG. 2 and 3 are diagrams showing a method of manufacturing the overvoltage protection component according to the first embodiment of the present invention. FIGS. 2 (a) to 2 (d) and FIGS. 3 (a) to 3 (d) The front sectional views, FIGS. 2 (e) to 2 (h) and FIGS. 3 (e) to 3 (h) are respectively plan views.

  As shown in FIGS. 2A and 2E, first, a first insulating sheet 11 made of an unfired ceramic green sheet is prepared.

  Next, as shown in FIGS. 2B and 2F, the first conductive layer 12 is formed by printing a paste-like mixture of gold and resin on the first insulating sheet 11.

  Next, as shown in FIGS. 2 (c) and 2 (g), the first insulating sheet 11 is made of an unfired ceramic green sheet having a discharge cavity portion 14 that is a rectangular opening at a substantially central portion. The second insulating sheet 13 is laminated. The second insulating sheet 13 may be formed by printing ceramic paste.

  Next, as shown in FIGS. 2D and 2H, a third insulating sheet 15 having the same shape and material as the first insulating sheet 11 is prepared.

  Next, as shown in FIGS. 3A and 3E, a paste-like mixture of gold and resin is printed on the upper surface of the third insulating sheet 15 to form the second conductive layer 16.

  Next, as shown in FIGS. 3 (b) and 3 (f), the product after the process of FIGS. 2 (c) and 2 (g) is added to the product after the process of FIGS. 3 (a) and 3 (e). Laminate the objects upside down. That is, the second conductive layer 16 is laminated in a direction facing the discharge cavity 14. At this time, the first conductive layer 12 and the second conductive layer 16 are set to extend in opposite directions. That is, when the first conductive layer 12 extends in the direction extending to the right end face of the first insulating sheet 11, the second conductive layer 16 extends in the direction extending to the left end face opposite to this.

  Next, baking is performed in the state of FIGS. Thereby, as shown in FIGS. 3C and 3G, the first insulating sheet 11, the second insulating sheet 13, and the third insulating sheet 15 are integrated to form the element body 1. The first conductive layer 12 becomes the second discharge electrode 4, and the second conductive layer 16 becomes the first discharge electrode 3. At this time, the resin contained in the first conductive layer 12 and the second conductive layer 16 disappears from the first conductive layer 12 and the second conductive layer 16 due to evaporation by baking or the like, and the first discharge. The electrode 3 and the second discharge electrode 4 are made of gold.

  Next, as shown in FIGS. 3 (d) and 3 (h), the first terminal electrode 5 is placed on the end face of the element body 1 where the first discharge electrode 3 is exposed, and the second discharge electrode 4. A second terminal electrode 6 is formed on each end face where the slab is exposed. The first terminal electrode 5 and the second terminal electrode 6 are obtained by printing a mixture of silver and resin and firing it. In consideration of mountability and the like, a nickel plating layer and further a tin plating layer may be formed on the surfaces of the first terminal electrode 5 and the second terminal electrode 6. Further, the first terminal electrode 5 and the second terminal electrode 6 may be formed of silver by a thin film method or the like.

  Through the above steps, the overvoltage protection component 7 can be obtained.

  In consideration of mass productivity, before the firing step shown in FIGS. 3C and 3G, a large first insulating sheet 11 or the like is used to manufacture a plurality of overvoltage protection components at a time. Alternatively, immediately before the firing step, the individual overvoltage protection components may be divided and the subsequent manufacturing steps may be performed.

  Moreover, although the 1st discharge electrode 3 and the 2nd discharge electrode 4 were formed with the gold | metal | money by a printing method, it can also be set as the mixture of gold | metal | money and resin by reducing the temperature at the time of baking. Moreover, when forming with gold | metal | money, it can form by thin film construction methods, such as sputtering.

  Furthermore, the first discharge electrode 3 and the second discharge electrode 4 are configured to face each other in the thickness direction via the discharge cavity portion 2, but the first discharge electrode 3 and the second discharge electrode 4 are disposed in the discharge cavity. It may be configured to be formed on the same surface in the portion 2 and to face each other through a gap at the tip of each other.

  The operation of the overvoltage protection component 7 configured and manufactured as described above will be described below.

  The first terminal electrode 5 is connected to the electronic component to be protected from overvoltage on the side where the voltage is applied, and the second terminal electrode 6 is connected to the ground side. The connection may be reversed. In this state, when a normal voltage is applied, no discharge occurs between the first discharge electrode 3 and the second discharge electrode 4 separated by the discharge cavity 2, and electricity flows to the electronic component.

  However, when an overvoltage is applied, a discharge occurs between the first discharge electrode 3 and the second discharge electrode 4, and at this time, electricity due to the overvoltage flows through the overvoltage protection component 7, and the current due to the overvoltage flows through the electronic component. Does not flow, the electronic component can be protected from overvoltage.

  As described above, the overvoltage protection component of the first embodiment includes the element body 1 obtained by firing the ceramic, the discharge cavity portion 2 formed inside the element body 1, and the discharge cavity portion 2. The first discharge electrode 3 and the second discharge electrode 4 that are formed at a distance from each other, and are electrically connected to the first discharge electrode 3 and the second discharge electrode 4 that are formed outside the element body 1, respectively. The first terminal electrode 5 and the second terminal electrode 6 are provided, and the first discharge electrode 3 and the second discharge electrode 4 are made of gold or a mixture of gold and resin. As a result, the first discharge electrode 3 and the second discharge electrode 4 do not react with the residue generated by firing the ceramic, so that deterioration of discharge characteristics can be prevented.

(Embodiment 2)
Hereinafter, the second aspect of the present invention will be described in particular.

  The second embodiment is different from the first embodiment in that rhodium is added to the first discharge electrode 3 and the second discharge electrode 4. Others are the same as in the first embodiment, and the drawings in FIGS. 1 and 2 can be applied to the second embodiment.

  By adding rhodium, planarization of the surfaces of the first discharge electrode 3 and the second discharge electrode 4 can be prevented. Since discharge is likely to occur from a pointed portion, it becomes difficult to discharge when the surfaces of the first discharge electrode 3 and the second discharge electrode 4 become flat, but this can be prevented by adding rhodium. The inventors speculate that the addition of rhodium and planarization of the surfaces of the first discharge electrode 3 and the second discharge electrode 4 are due to the following mechanism.

  Rhodium has a high melting point, and what forms a solid solution with gold is about 10% at a weight ratio. Therefore, a large amount of rhodium exists as rhodium particles even in the ceramic firing step. Therefore, it is considered that rhodium particles exist around the gold particles, thereby preventing crystal grain growth between the gold particles. And when grain growth is suppressed, it will be in the state where many fine particles exist, and it is thought that the planarization of the surface of the 1st discharge electrode 3 and the 2nd discharge electrode 4 is suppressed.

  The distribution of rhodium is 0.5% of gold by weight ratio, but is not limited to this, and is 0.2 to 1.5%, more preferably 0.3 to 1.0%. Is appropriate.

(Embodiment 3)
Hereinafter, the third aspect of the present invention will be described in particular.

  FIG. 4 is a front cross-sectional view of the overvoltage protection component in Embodiment 3 of the present invention.

  The third embodiment is different from the second embodiment in that an alloy portion 8 is provided between the first discharge electrode 3 and the first terminal electrode 5, and the second discharge electrode 4 and the second terminal electrode 6. The alloy part 9 is formed between the two.

  Both the alloy part 8 and the alloy part 9 have an alloy of gold and silver. The manufacturing method is basically the same as that in the first embodiment, but the differences will be described below.

  First, the first difference is that the steps of FIGS. 2B and 2F in Embodiment 1 are replaced with the steps of FIGS. 5A and 5C and FIGS. 5B and 5D. is there.

  5A and 5C, the first conductive layer 12 is applied on the first insulating sheet 11. At this time, an unfired ceramic sheet is used for the first insulating sheet 11 as in the first embodiment. The first conductive layer 12 is made by adding rhodium to gold and resin, and is printed in a paste state. At this time, in the first embodiment, the first conductive layer 12 is printed to the right end on the upper surface of the first insulating sheet 11, but in the third embodiment, the first end is not applied to the right end, and the right end is applied. An area not coated is provided between the two.

  5B and 5D, the alloy layer 17 is applied by printing to the right end of the upper surface of the first insulating sheet 11 where the first conductive layer 12 is not applied. The alloy layer 17 is formed by applying a paste of a mixture of an alloy of gold and silver and a resin. Note that the resin is evaporated from the alloy layer 17 by subsequent firing.

  In addition, the alloy part 9 can be made into the mixture of an alloy of gold | metal | money and silver and resin by lowering | calculating firing temperature. Moreover, the alloy part 9 is good also as what added rhodium to the alloy of gold | metal | money and the 2nd discharge electrode 4 being what added rhodium to gold | metal | money.

  Another difference of the third embodiment from the manufacturing method of the first embodiment is that FIGS. 3A and 3E are different from the first difference. 3A and 3E of the first embodiment, similarly to the first difference, the second conductive layer 16 is not printed and applied to the right end of the upper surface of the third insulating sheet 15, This is to print and apply the alloy layer 17 to the unapplied region. In this step, in FIGS. 5A and 5C and FIGS. 5B and 5D, the first insulating sheet 11 is replaced with the third insulating sheet 15, and the first conductive layer 12 is replaced with the second conductive sheet 12. The conductive layer 16 is replaced.

  The overvoltage protection component obtained by the above configuration and manufacturing method is an alloy containing an alloy of gold and silver between the first discharge electrode 3 containing gold and the first terminal electrode 5 containing silver. Part 8, and similarly, an alloy part 9 is provided between the second discharge electrode 4 and the second terminal electrode 6, so that the adhesion between the first discharge electrode 3 and the alloy part 8, the alloy Since the adhesion between the part 8 and the first terminal electrode 5, the adhesion between the second discharge electrode 4 and the alloy part 9, and the adhesion between the alloy part 9 and the second terminal electrode 6 are excellent, the first The electrical connection reliability between the discharge electrode 3 and the first terminal electrode 5 and between the second discharge electrode 4 and the second terminal electrode 6 is increased.

  The overvoltage protection component according to the present invention can prevent deterioration of discharge characteristics due to oxidation or the like of the discharge electrode, and can be applied to various electric devices and electronic devices.

DESCRIPTION OF SYMBOLS 1 Element body 2 Discharge cavity part 3 1st discharge electrode 4 2nd discharge electrode 5 1st terminal electrode 6 2nd terminal electrode 7 Overvoltage protection component 8 Alloy part 9 Alloy part 11 1st insulating sheet 12 1st Conductive layer 13 Second insulating sheet 14 Discharge cavity 15 Third insulating sheet 16 Second conductive layer 17 Alloy layer

Claims (3)

An element body obtained by firing ceramic;
A discharge cavity formed inside the element;
A pair of discharge electrodes formed at intervals in the discharge cavity;
A pair of terminal electrodes electrically connected to the pair of discharge electrodes formed outside the element body;
The pair of discharge electrodes are overvoltage protection components that are gold or a mixture of gold and resin. The overvoltage protection component according to claim 1, wherein rhodium is added to the discharge electrode. 3. The overvoltage protection component according to claim 2, wherein the terminal electrode is made of silver or silver and a resin, and an alloy part having an alloy of gold and silver is provided between the discharge electrode and the terminal electrode.

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