JP2010231910A - Overvoltage protection component - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an overvoltage protection component capable of lowering a discharge starting voltage and shifting smoothly to a main discharge from starting of discharge. <P>SOLUTION: The overvoltage protection component includes a first element body 1, a second element body 2 formed inside the first element body 1, a discharge cavity 3 which is a space surrounded by the second element body 2 or a space surrounded by the first element body 1 and the second element body 2, a first discharge electrode 4 of which at least the part is formed in contact with the second element body 2 inside the discharge cavity 3, a second discharge electrode 5 formed opposed to the first discharge electrode 4 each other, a first terminal electrode 6 which is formed outside of the first element body 1 and is connected electrically with the first discharge electrode 4, and a second terminal electrode 7 which is formed outside of the first element body 1 and is connected electrically with the second discharge electrode 5. The second element body 2 becomes conductive by a mixture of ceramic and conductor powder at an overvoltage being applied and functions as an insulator in other cases. <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, two electrodes are arranged to face each other in the plane direction, and the two electrodes are insulated during normal operation, but when overvoltage is applied, the overvoltage is two electrodes. Some have a function of discharging the gap (see Patent Document 1).

Also known is an overvoltage protection component in which a lid is formed of a mixture of a conductor and an insulator, discharge start is conducted through a conductor constituting the lid, and main discharge is performed between discharge electrodes (Patent Document). 2).
JP-A-1-102884 JP 2001-345161 A

  In recent years, with the miniaturization of electronic devices and electronic components, the tolerance to overvoltage has further decreased, and the allowable voltage value for the electronic components has decreased. In order to cope with a decrease in the voltage value allowed by the electronic component, a voltage at which the overvoltage protection component conducts electricity, that is, a decrease in the discharge start voltage (trigger voltage) is required. One means for reducing the discharge start voltage is to shorten the distance between the two electrodes.

  However, there is a balance with manufacturing accuracy, and there is a limit to lowering the discharge start voltage by a method of shortening the distance between the electrodes.

  Further, as another means for lowering the discharge start voltage, the structure as in Patent Document 2 is adopted, and instead of starting discharge between a pair of discharge electrodes, a lid for a space including the pair of discharge electrodes A method is also conceivable in which a metal is formed of a mixture of an insulator and a conductor, and a discharge is generated between the conductors of the lid. However, in this case, at the start of discharge, discharge is performed at the portion that contacts the lid of the discharge electrode, and at the main discharge, discharge is performed at the tip of the discharge electrode, and the place where both occur is different, The discharge did not always move smoothly from the start of discharge to the main discharge.

  SUMMARY OF THE INVENTION The present invention solves the above-described conventional problems, and an object of the present invention is to realize an overvoltage protection component capable of smoothly shifting from the start of discharge to the main discharge while reducing the discharge start voltage.

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

  According to the first aspect of the present invention, a first element body, a second element body formed inside the first element body, and a space surrounded by the second element body or the first element body A discharge cavity that is a space surrounded by the element body and the second element body, and a first discharge formed at least partially in contact with the second element body in the discharge cavity part An electrode, a second discharge electrode formed so as to be at least partially in contact with the second element body in the discharge cavity and facing the first discharge electrode in a plane direction; A first terminal electrode formed outside the first element body and electrically connected to the first discharge electrode; and formed outside the first element body and electrically connected to the second discharge electrode. The second element body is a mixture of the ceramic and conductive powder, and is conductive when an overvoltage is applied. In functions as an insulator.

  According to this configuration, the invention according to claim 1 is characterized in that the second element body is a mixture of the ceramic and conductor powder and is conductive when an overvoltage is applied, and otherwise functions as an insulator. This has the effect of reducing the starting voltage. Furthermore, at the start of discharge, by discharging the conductor powder in the second element body, discharge is performed between the peripheral portion of the first discharge electrode and the peripheral portion of the second discharge electrode, and the main discharge is By discharging the space in the discharge cavity, discharge is performed between the peripheral portion of the first discharge electrode and the peripheral portion of the second discharge electrode, and both discharges are performed in the first discharge electrode. Since this is performed at the peripheral portion of the second discharge electrode and the peripheral portion of the second discharge electrode, there is also an effect that the discharge is smoothly transferred from the discharge start to the main discharge.

  In the invention described in claim 2, in particular, the second element body is made of ceramic and metal powder having a melting point higher than the firing temperature of the ceramic. According to this structure, the ceramic is fired. Since the conductor powder does not melt at this time, the conductor powder exists in a powder form, and therefore, the conductor powder exists in a moderately dispersed manner in the second element body, so that the discharge characteristics are stabilized. It has an effect.

  In particular, the second element body is a mixture of a low-temperature co-fired ceramic and a conductor powder. According to this configuration, the conductor powder in the second element body is compared. Even if silver or copper having a low melting point is used, it does not melt and remains as a powder in the second element body, so that it has the effect of stabilizing the discharge characteristics. It is.

  As described above, the overvoltage protection component of the present invention has an effect that the discharge start voltage can be lowered and the transition from the discharge start state to the main discharge can be smoothly performed.

  The invention described in claims 1 and 2 of the present invention will be described below.

  FIG. 1 is a front sectional view of an overvoltage protection component in an embodiment of the present invention.

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

  The second element body 2 is formed inside the first element body 1 and is made of a mixture of ceramic and conductor powder. The second element body 2 is also required not to be damaged even if a discharge occurs inside. In particular, when a low-temperature co-fired ceramic is used for the ceramic, the conductor powder does not melt and remains in a powder form when the second element body 2 is fired. Since the conductor powder is present in the body 2, it is preferable in that the discharge characteristics are stabilized.

The discharge cavity 3 is a substantially rectangular parallelepiped cavity formed inside the second element body 2, and discharge is generated in the cavity when an overvoltage is applied.

  The first discharge electrode 4 is provided inside the first element body 1 and the second element body 2, and a part of the first discharge electrode 4 is exposed to the discharge cavity 3. The second discharge electrode 5 is also provided inside the first element body 1 and the second element body 2, and a part of the second discharge electrode 5 is exposed to the discharge cavity 3. The first discharge electrode 4 and the second discharge electrode 5 are formed such that one of the inner walls of the discharge cavity 3 is formed on the bottom surface and the other is formed on the ceiling surface facing the first wall, and is opposed to each other in the surface direction. The first discharge electrode 4 and the second discharge electrode 5 are required to use a material having excellent conductivity and excellent heat resistance, and it is preferable to use a metal. Among metals, copper, gold, palladium, or an alloy thereof may be used if conductivity is important, and tungsten or molybdenum may be used if heat resistance is important.

  The first terminal electrode 6 is formed outside the first element body 1 and is electrically connected to the first discharge electrode 4, and the second terminal electrode 7 is located outside the first element body 1. Formed and electrically connected to the second discharge electrode 5.

  The overvoltage protection component 8 has the above configuration.

  Next, a manufacturing method will be described with reference to FIGS. 2-4 is a figure which shows the manufacturing method of the overvoltage protection component in one embodiment of this invention, FIG.2 (a)-FIG.2 (d), FIG.3 (a)-FIG.3 (d), 4 (a) to 4 (d) are front sectional views, respectively, FIG. 2 (e) to FIG. 2 (h), FIG. 3 (e) to FIG. 3 (h), and FIG. 4 (e) to FIG. (H) is a plan view of each.

  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, a second insulating sheet 12 made of an unfired ceramic green sheet having a rectangular opening at a substantially central portion on the first insulating sheet 11 is provided. Laminate. The second insulating sheet 12 may be formed by printing a ceramic paste.

  Next, as shown in FIGS. 2C and 2G, the first discharge body 13 is formed in the opening of the second insulating sheet 12. The first discharge body 13 can be formed by applying a paste of a mixture of unfired ceramic and conductor powder.

  Next, as shown in FIGS. 2D and 2H, the first conductor layer 14 is formed at predetermined positions on the second insulating sheet 12 and the first discharge body 13. The first conductor layer 14 finally becomes the second discharge electrode 5, and a printing method can be used as a method for forming the first conductor layer 14.

  Next, as shown in FIGS. 3A and 3E, a second insulating sheet 12 and a third insulating sheet 15 having a rectangular opening at a substantially central portion are laminated on the first conductor layer 14. To do. Lamination is performed so that the first discharge body 13 is exposed from the opening of the third insulating sheet 15 and a part of the first conductor layer 14 is also exposed. The third insulating sheet 15 can also be made of an unfired ceramic green sheet. The third insulating sheet 15 may be formed by printing a ceramic paste.

  Next, as shown in FIGS. 3B and 3F, the second discharge body 16 is formed in the opening of the third insulating sheet 15. The second discharge body 16 has a rectangular opening at a substantially central portion, and can be formed by applying a paste of a mixture of unfired ceramic and conductor powder.

  Next, as shown in FIGS. 3C and 3G, a resin paste body 17 is formed in the opening of the second discharge body 16. As the resin paste body 17, a material that disappears by evaporation, decomposition, or the like in a subsequent baking step can be used. For example, acrylic beads can be used as fillers.

  Next, as shown in FIGS. 3D and 3H, the second conductor layer 18 is formed at predetermined positions on the third insulating sheet 15, the second discharge body 16, and the resin paste body 17. . The second conductor layer 18 finally becomes the first discharge electrode 4, and the same material as that of the first conductor layer 14 can be used.

  Next, as shown in FIGS. 4A and 4E, a fourth insulating sheet 19 made of an unfired ceramic green sheet having a rectangular opening at a substantially central portion on the third insulating sheet 15 is provided. Laminate. The 4th insulating sheet 19 can use the same shape as the 2nd insulating sheet 12, and from this opening part, the 2nd discharge body 16, the resin paste body 17, and the 2nd conductor layer 18 are used. Laminate so that a part of is exposed. Further, the third discharge body 20 is formed in the opening of the fourth insulating sheet 19. The third discharge body 20 can be formed by applying a paste of a mixture of unfired ceramic and conductor powder.

  Next, as shown in FIGS. 4B and 4F, a fifth insulating sheet 21 made of an unfired ceramic green sheet is laminated on the fourth insulating sheet 19 and the third discharge body 20.

  Next, a baking process is performed, and the first insulating sheet 11, the second insulating sheet 12, the first discharge body 13, the first conductor layer 14, the third insulating sheet 15, the second discharge body 16, The resin paste body 17, the second conductor layer 18, the fourth insulating sheet 19, the third discharge body 20, and the fifth insulating sheet 21 are fired. Thus, as shown in FIGS. 4C and 4G, the first insulating sheet 11, the second insulating sheet 12, the third insulating sheet 15, the fourth insulating sheet 19, and the fifth insulating sheet. 21 is integrated into the first element body 1. The first discharge body 13, the second discharge body 16, and the third discharge body 20 are integrated into the second element body 2. Further, the first conductor layer 14 becomes the second discharge electrode 5, and the second conductor layer 18 becomes the first discharge electrode 4. The resin paste 17 disappears when its components such as resin and solvent are decomposed and evaporated, and the space in which the resin paste 17 is present becomes a cavity and becomes the discharge cavity 3.

  Next, as shown in FIGS. 4D and 4H, the first terminal electrode 6 and the second terminal electrode 7 are formed on the end face of the first element body 1, so that the overvoltage protection component 8 is formed. can get. Specifically, for the first terminal electrode 6 and the second terminal electrode 7, after forming a copper electrode by printing, a nickel plating layer is formed on the surface by electrolytic plating, and a tin plating layer is further formed on the surface. Can be taken.

  In consideration of mass productivity, before the firing step, the large first insulating sheet 11 or the like is used to manufacture a plurality of overvoltage protection parts at once, and immediately before the firing step, individual piece overvoltage protection is performed. You may make it divide | segment into components and perform a subsequent manufacturing process.

  The operation of the overvoltage protection component 8 configured and manufactured as described above will be described below.

  A first terminal electrode 6 is connected to a side to which a voltage is applied to an electronic component to be protected from overvoltage, and a second terminal electrode 7 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 4 and the second discharge electrode 5 separated by the discharge cavity 3, and electricity flows to the electronic component.

  However, when an overvoltage is applied, a discharge occurs between the first discharge electrode 4 and the second discharge electrode 5, and at this time, electricity due to the overvoltage flows through the overvoltage protection component 8, and current due to the overvoltage flows through the electronic component. Does not flow, the electronic component can be protected from overvoltage.

  Here, in general, discharge is likely to occur when the voltage is high and difficult to occur when the voltage is low. However, the discharge start voltage, which is the minimum voltage value at which discharge occurs, is the distance between the two electrodes where discharge occurs. It is related, and when the distance between electrodes is short, it is easy to discharge, and when long, it is difficult to discharge.

  In the overvoltage protection component 8 according to the present invention, the second element body 2 is made of a mixture of ceramic and conductor powder, and discharge easily occurs due to the presence of the conductor powder. A discharge start voltage lower than the discharge start voltage due to the distance in the discharge cavity 3 between the two discharge electrodes 5 can be realized.

  Further, it is well known that discharge is generally likely to occur at the pointed portion of the electrode, and the overvoltage protection component 8 of the present invention is a conductive powder in the second element body 2 at the start of discharge. A discharge is performed between the peripheral portion of the first discharge electrode 4 and the peripheral portion of the second discharge electrode 5 by way of a path for discharging between them, and during the main discharge, the discharge cavity 3 A discharge is performed between the peripheral portion of the first discharge electrode 4 and the peripheral portion of the second discharge electrode 5 through the path for discharging the space, and both discharges are performed in the first discharge electrode. 4 and the periphery of the second discharge electrode 5, the discharge is smoothly transferred from the discharge start state to the main discharge.

  In the overvoltage protection component 8, the second element body 2 is present on the surface on which the first discharge electrode 4 and the second discharge electrode 5 are formed and the surface connecting the two surfaces. It is not necessary to be formed on the entire inner wall of the first element body 1.

  Moreover, as an average particle diameter of the conductor powder at the time of forming the 2nd element | base_body 2, about 0.1-10 micrometers is preferable. The component ratio of the ceramic and the conductor powder affects the distance between the conductor powders in the second element body 2 and is related to the discharge start voltage. Accordingly, it may be determined appropriately.

  Furthermore, the ceramic that is a component of the first element body 1 and the ceramic that is one of the elements of the second element body 2 may be made of the same material. In this way, the firing temperature for producing the first element body 1 and the firing temperature for producing the second element body 2 are substantially the same, so that the production process is simplified.

  Further, when a material is used in which the temperature at which the ceramic constituting the second element body 2 is fired is lower than the melting point of the metal powder constituting the second element body 2, the metal in the second element body 2 is used. It is preferable because the powder is appropriately dispersed and the discharge characteristics are stabilized. A suitable example of such a ceramic is a low-temperature co-fired ceramic.

  The overvoltage protection component and the method for manufacturing the same according to the present invention can reduce the discharge start voltage, and thus have an excellent effect of being able to protect electronic components and the like that are more susceptible to overvoltage.

Front sectional drawing of the overvoltage protection component in one embodiment 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 The figure which shows the manufacturing method of the same overvoltage protection component

DESCRIPTION OF SYMBOLS 1 1st element body 2 2nd element body 3 Discharge cavity part 4 1st discharge electrode 5 2nd discharge electrode 6 1st terminal electrode 7 2nd terminal electrode 8 Overvoltage protection component 11 1st insulating sheet 12 2nd insulation sheet 13 1st discharge body 14 1st conductor layer 15 3rd insulation sheet 16 2nd discharge body 17 resin paste body 18 2nd conductor layer 19 4th insulation sheet 20 3rd Discharge body 21 5th insulating sheet

Claims (3)

A first element body;
A second element body formed inside the first element body;
A discharge cavity that is a space surrounded by the second element body or a space surrounded by the first element body and the second element body;
A first discharge electrode formed at least partially in contact with the second element body at the discharge cavity;
A second discharge electrode formed so as to be at least partially in contact with the second element body in the discharge cavity and facing the first discharge electrode in a plane direction;
A first terminal electrode formed outside the first element body and electrically connected to the first discharge electrode;
A second terminal electrode formed outside the first element body and electrically connected to the second discharge electrode;
The second element body is an overvoltage protection component that is a mixture of the ceramic and the conductive powder and is conductive when an overvoltage is applied, and otherwise functions as an insulator. 2. The overvoltage protection component according to claim 1, wherein the second element body is made of ceramic and metal powder having a melting point higher than a firing temperature of the ceramic. The overvoltage protection component according to claim 2, wherein the second element body is a mixture of a low-temperature co-fired ceramic and a conductor powder.

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