JP2010086841A - Overvoltage protection component and its manufacturing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an overvoltage protection component which has resistance against repetitive application of overvoltage such as static electricity and surge, and has a low peak voltage applied to the overvoltage protection component and stabilized characteristics to protect an electronic device from overvoltage. <P>SOLUTION: The overvoltage protection component incldues a cavity 23 formed inside a base body 22, and first and second electrodes 13, 14 opposing each other through a first gap 12 in the cavity 23. Third and fourth electrodes 20, 21 opposing each other through a second gap 19 are arranged on an upper surface of the base body 22, a first terminal electrode 24 for electrically connecting between the first electrode 13 and the third electrode 20 is formed on one side face of the base body 22, and a second terminal electrode 25 for electrically connecting between the second electrode 14 and the fourth electrode 21 is formed on the other side face of the base body 22. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an overvoltage protection component that protects an electronic device from overvoltage such as 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, the tolerance of overvoltages such as static electricity and surges of electronic devices and electronic parts has decreased, and countermeasure parts such as microgap-type overvoltage protection parts have been used as countermeasures. Yes.

For example, Patent Documents 1 and 2 are known as prior art document information relating to the invention of this application.
Japanese Patent Laid-Open No. 9-266053 Japanese Patent Laid-Open No. 1-137584

  As shown in FIG. 15, a conventional surge surge absorber as an overvoltage protection component has a pair of electrodes 3, 4 facing each other with a microgap 2 in the discharge space 1. , 4, when an overvoltage such as static electricity or surge is applied, the microgap 2 is discharged and a current flows, and the electronic device is protected by bypassing this current to the ground.

  However, when an overvoltage such as static electricity or surge is repeatedly applied, the discharge of the microgap 2 is repeated, whereby the pair of electrodes 3 and 4 constituting the microgap 2 generate heat and gradually dissolve. And the interval of the micro gap 2 is widened, and the peak voltage at which the overvoltage protection component operates increases. As a result, the effect of protecting the electronic device from overvoltage such as static electricity and surge cannot be obtained satisfactorily. there were.

  Further, in Patent Document 2, a sealed container is provided with a carbon electrode facing with a discharge gap G1 and a metal box facing with a discharge gap G2, and a discharge gap from the discharge gap G1. By adopting a configuration in which G2 is increased, when an overvoltage is applied, the carbon electrode portion (G1) is discharged in the low voltage region, while the metal box portion (G2) is discharged in the high voltage region. A surge absorber is shown in which the discharge characteristics are stable even after long-term use by delaying the deterioration of the carbon electrode. However, in the configuration shown in Patent Document 2, since the configuration is such that the opening portions at both ends of the cylindrical insulator are sealed with a pair of metal plates, the structure becomes complicated. It was also difficult to reduce the size.

  The present invention solves the above-described conventional problems, is resistant to repeated application of overvoltage such as static electricity and surge, and has a low peak voltage applied to overvoltage protection components and stable characteristics for protecting electronic devices from overvoltage. It is an object of the present invention to provide an overvoltage protection component and a manufacturing method thereof.

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

  According to a first aspect of the present invention, there is provided a substrate, a cavity formed in the substrate, a first electrode and a second electrode facing each other with a first gap in the cavity. A third electrode and a fourth electrode facing each other across a second gap are provided on the upper surface of the substrate, and the first electrode and the third electrode are electrically connected to one side surface of the substrate. A first terminal electrode that is electrically connected, and a second terminal electrode that electrically connects the second electrode and the fourth electrode is formed on the other side surface of the substrate. According to the above, the third electrode and the fourth electrode facing each other with a second gap are provided on the upper surface of the substrate, and the first electrode and the third electrode are provided on one side surface of the substrate. First terminal electrode to be electrically connected In addition, since the second terminal electrode for electrically connecting the second electrode and the fourth electrode is formed on the other side surface of the base, an initial stage of applying an overvoltage such as static electricity or surge , The discharge start voltage is low, only the first gap provided in the cavity inside the base body is discharged, the overvoltage protection component operates, and then the overvoltage application is repeated to degrade the first gap. When the discharge start voltage of the first gap rises, the second gap provided on the upper surface of the substrate also functions and discharges simultaneously with the first gap, so that the overvoltage protection component continues to operate. Therefore, the electric field is not concentrated only in the first gap, and thus the electronic device can be reliably protected from repeated application of overvoltage such as static electricity or surge. And it has a effect that the voltage protection components obtained.

  In addition, a third electrode and a fourth electrode facing each other with a second gap are formed on the upper surface of the base, and a first electrode and a second electrode facing each other with a first gap are formed inside the base. Since the second electrode is formed, the upper surface of the base body and the inside of the base body can be effectively used, and thereby, the overvoltage protection component can be reduced in size.

  In the invention described in claim 2 of the present invention, in particular, the substrate is constituted by laminating and firing low-temperature fired ceramic sheets, and the first electrode and the second electrode are made of gold, silver palladium alloy, or silver. According to this configuration, the substrate is configured by laminating and firing low-temperature fired ceramic sheets, and the first electrode and the second electrode are made of gold, silver palladium alloy, silver Since any one of the main components is used, the first insulating layer to the third insulating layer and the first electrode to the fourth electrode constituting the base can be simultaneously fired at 1000 ° C. or lower. As a result, a product excellent in mass productivity can be obtained, so that the cost of the overvoltage protection component can be reduced.

  According to a third aspect of the present invention, there is provided a step of forming the first electrode and the second electrode so as to face the upper surface of the first insulating layer with a first gap therebetween, and Forming a second insulating layer so as to cover a portion of the insulating layer other than the cavity forming portion in the vicinity of the first gap; filling the cavity forming portion with a resin; and A step of forming a third insulating layer so as to completely cover the insulating layer and the resin, and a second gap is formed by cutting the conductor layer formed on the upper surface of the third insulating layer with a laser. Forming a third electrode and a fourth electrode facing each other across the second gap, the first insulating layer to the third insulating layer, and the first electrode to the fourth electrode Is fired simultaneously to eliminate the resin filled in the cavity forming part, A step of forming a cavity in the vicinity of the first gap, and a step of forming a first terminal electrode by applying a conductive paste so that the first electrode and the third electrode are electrically connected. And a step of forming a second terminal electrode by applying a conductive paste so that the second electrode and the fourth electrode are electrically connected. According to this manufacturing method, The first electrode and the second electrode are opposed to each other with a first gap in the cavity inside the substrate, and the third electrode and the fourth electrode are opposed to each other with a second gap on the upper surface of the substrate. Oppositely, the first electrode and the third electrode are electrically connected by a first terminal electrode on one side surface of the substrate, and the second electrode and the fourth electrode are further connected on the other side surface of the substrate. Are electrically connected by the second terminal electrode; Therefore, in the initial stage of application of overvoltage such as static electricity or surge, the discharge start voltage is low, only the first gap provided in the cavity inside the base body is discharged, the overvoltage protection component operates, and After that, when overvoltage application is repeated and the first gap deteriorates and the discharge start voltage of the first gap rises, the second gap provided on the upper surface of the substrate also functions simultaneously with the first gap. Since the overvoltage protection component continues to operate by discharging the electric field, the electric field is not concentrated only in the first gap, thereby reliably preventing the electronic device from being repeatedly applied with an overvoltage such as static electricity or surge. The overvoltage protection component that can be protected is obtained.

  In addition, since the first insulating layer to the third insulating layer and the first electrode to the fourth electrode are simultaneously fired to eliminate the resin filled in the cavity forming portion, a plurality of stacked insulating layers Simultaneously with the step of firing the layer and the plurality of electrodes, the resin can be lost to form a cavity in the vicinity of the first gap, thereby reducing the number of steps and reducing the cost of the overvoltage protection component. It is what has.

  According to a fourth aspect of the present invention, there is provided a step of forming a first electrode on the upper surface of the first insulating layer, and a portion of the first electrode is not covered on the first insulating layer. Forming one second insulating layer as described above, and the other second insulating layer on the first electrode so as to face the one second insulating layer with a first gap therebetween A step of filling the cavity forming portion in the vicinity of the first gap that is not covered with the second insulating layer on the first insulating layer, and both the second Forming a second electrode on the insulating layer so as to at least partially overlap the resin, and forming a third insulating layer so as to completely cover the second insulating layer and the second electrode; The step and the conductor layer formed on the upper surface of the third insulating layer are cut with a laser to form the second gap. And forming a third electrode and a fourth electrode facing each other with the second gap therebetween, a first insulating layer to a third insulating layer, and a first electrode to a fourth electrode. Simultaneously firing the electrodes to eliminate the resin filled in the cavity forming portion and forming a cavity in the vicinity of the first gap, and electrically connecting the first electrode and the third electrode. A step of applying a conductive paste to form a first terminal electrode, and applying a conductive paste so that the second electrode and the fourth electrode are electrically connected to each other. According to this manufacturing method, the first electrode and the second electrode are opposed to each other with a first gap in the cavity inside the substrate, and the substrate is formed on the substrate. On the top surface, the third electrode and the fourth electrode have a second gap. The first electrode and the third electrode are electrically connected by a first terminal electrode on one side surface of the substrate, and the second electrode and the third electrode on the other side surface of the substrate. In the initial stage of application of overvoltage such as static electricity or surge, the discharge start voltage is low and the electrode 4 is provided in a cavity inside the substrate. In the case where only the first gap is discharged and the overvoltage protection component operates, and then the overgap application is repeated and the first gap deteriorates to increase the discharge start voltage of the first gap. Since the second gap provided on the upper surface of the substrate also functions and discharges simultaneously with the first gap, the overvoltage protection component continues to operate, so that the electric field is concentrated only on the first gap. Thus, an overvoltage protection component capable of reliably protecting an electronic device from repeated application of overvoltage such as static electricity or surge is obtained.

  In addition, since the first insulating layer to the third insulating layer and the first electrode to the fourth electrode are simultaneously fired to eliminate the resin filled in the cavity forming portion, a plurality of stacked insulating layers Simultaneously with the step of firing the layer and the plurality of electrodes, the resin can be lost to form a cavity in the vicinity of the first gap, thereby reducing the number of steps and reducing the cost of the overvoltage protection component. It is what has.

  As described above, the overvoltage protection component of the present invention includes a base, a cavity formed in the base, and the first electrode and the second electrode facing each other with a first gap in the cavity. A third electrode and a fourth electrode facing each other across a second gap are provided on the upper surface of the substrate, and the first electrode and the third electrode are electrically connected to one side surface of the substrate. A first terminal electrode that is electrically connected, and a second terminal electrode that electrically connects the second electrode and the fourth electrode is formed on the other side surface of the base. In the initial stage of application of overvoltage such as static electricity or surge, the discharge start voltage is low, only the first gap provided in the cavity inside the substrate is discharged, the overvoltage protection component operates, and then overvoltage application is repeated. When the first gap deteriorates and the discharge start voltage of the first gap increases, the second gap provided on the upper surface of the substrate also functions and discharges simultaneously with the first gap. Since the overvoltage protection component continues to operate, the electric field is not concentrated only in the first gap, and thus the electronic device can be reliably protected from repeated application of overvoltage such as static electricity or surge.

  In addition, a third electrode and a fourth electrode facing each other with a second gap are formed on the upper surface of the base, and a first electrode and a second electrode facing each other with a first gap are formed inside the base. Since the second electrode is formed, the upper surface of the base body and the inside of the base body can be used effectively, thereby producing an excellent effect that the overvoltage protection component can be reduced in size.

(Embodiment 1)
Hereinafter, the invention described in the first to third aspects of the present invention will be described using the first embodiment with reference to the drawings.

  1 is a cross-sectional view of an overvoltage protection component according to Embodiment 1 of the present invention, FIGS. 2 (a) to (d), FIGS. 3 (a) to (d), FIGS. 4 (a) to (d), and FIG. (A)-(d) is a manufacturing-process figure which shows the manufacturing method of the same overvoltage protection component. 2 (a) to (d) and FIGS. 3 (a) to (d) are cross-sectional views of the individual work pieces, and FIGS. 4 (a) to (d) and FIG. (a)-(d) has shown the top view of the piece-in-process in-process item.

  Hereinafter, the manufacturing method of the overvoltage protection component in Embodiment 1 of this invention is demonstrated.

  First, as shown in FIG. 2A and FIG. 4A, the first insulating layer 11 made of an unfired ceramic sheet is formed on the upper surface with a first gap 12 having an interval of 20 to 50 μm therebetween. The first electrode 13 and the second electrode 14 are formed with a thickness of 2 to 10 μm using a screen printing method so as to face each other. Here, the ceramic sheet constituting the first insulating layer 11 is made of, for example, a mixture of alumina powder and glass powder having a weight ratio of 40 to 60, a thickness of 20 to 50 μm, and a firing temperature of 800 to 1000 ° C. The first electrode 13 and the second electrode 14 are preferably made of a material mainly composed of gold, silver palladium alloy, or silver. 2A and 4A, the rectangular first insulating layer having a long side of L (mm) and a short side of W (mm), which is an individual size of the overvoltage protection component, is shown. 11 is shown in the description of the manufacturing process below, and this individual size insulating layer is used for explanation. However, in the actual manufacturing process, a large number of insulating layers of this individual size are arranged vertically and horizontally. A sheet-like insulating layer that can be obtained is used, and is divided into individual pieces before the firing step described later.

  Next, as shown in FIG. 2B and FIG. 4B, on the upper surface of the first insulating layer 11, avoid the formation of a cavity, that is, avoid the first gap 12 and its vicinity. A second insulating layer 15 made of an unfired ceramic sheet having a square or rectangular opening at the center is formed. Similarly to the first insulating layer 11, it is preferable to use a low-temperature fired ceramic also for the ceramic sheet constituting the second insulating layer 15.

  Next, as shown in FIG. 2C and FIG. 4C, a discharge space is formed in the vicinity of the first gap 12 located between the tip portions of the first electrode 13 and the second electrode 14. Resin 16 is filled into the cavity forming portion. The material of the resin 16 may be any material as long as it burns, decomposes, vaporizes, and disappears in a baking step to be described later. For example, acrylic beads that are a kind of acrylic resin can be used.

  Next, as shown in FIGS. 2D and 4D, a third insulating layer 17 made of an unfired ceramic sheet is formed so as to completely cover the second insulating layer 15 and the resin 16. To do. Similarly to the first insulating layer 11, it is preferable to use a low-temperature fired ceramic also for the ceramic sheet constituting the third insulating layer 17. In addition, after the third insulating layer 17 is formed, it is preferable to perform a pressing step in order to flatten the entire laminated insulating sheet and ensure dimensional accuracy.

  Next, as shown in FIGS. 3A and 5A, a conductor layer 18 is formed from one end of the third insulating layer 17 to the other end. The conductor layer 18 is preferably formed thinly and uniformly using a conductive material having excellent heat resistance. In this case, the conductive layer 18 may be formed using the same material as the first electrode 13 and the second electrode 14. Alternatively, a sputtered film mainly composed of any one of titanium, nickel, tungsten, and molybdenum may be formed in a single layer or a multilayer structure. In particular, when the conductor layer 18 has a three-layer structure of a first titanium thin film, an intermediate tungsten thin film, and a second titanium thin film, the first titanium thin film ensures adhesion to the third insulating layer 17. Further, an intermediate tungsten thin film having a low resistance value and excellent heat resistance can be obtained, and further, the second titanium thin film can suppress an increase in resistance value due to oxidation of the intermediate tungsten thin film surface. The conductor layer 18 having a low resistance and excellent heat resistance can be obtained by such a three-layer structure. The conductor layer 18 is formed wider than the widths of the first electrode 13 and the second electrode 14.

  Next, as shown in FIGS. 3B and 5B, the conductor layer 18 is cut using a UV laser to form a second gap 19 having an interval of 5 to 20 μm. A third electrode 20 and a fourth electrode 21 are formed opposite to each other with a gap 19 therebetween. In this case, the interval between the second gaps 19 is formed narrower than the interval between the first gaps 12, and the widths of the third electrode 20 and the fourth electrode 21 that are opposed to each other with the second gap 19 therebetween. Is formed wider than the width of the first electrode 13 and the second electrode 14 facing each other across the first gap 12.

  After the second gap 19 is formed, the work piece in sheet form is made into a piece state by using a break method, a dicing method or the like, and the first insulating layer 11, the second insulating layer 15, the third The insulating layer 17, the first electrode 13, the second electrode 14, the third electrode 20, and the fourth electrode 21 are simultaneously fired to form the base body 22. By performing this baking process, the resin 16 filled in the cavity forming portion is decomposed and vaporized to disappear, and as shown in FIGS. 3C and 5C, in the vicinity of the first gap 12. A cavity 23 serving as a discharge space is formed.

  Finally, as shown in FIG. 3 (d) and FIG. 5 (d), at one end of the substrate 22 in a single piece state so that the first electrode 13 and the third electrode 20 are electrically connected, The first terminal electrode 24 is formed by applying and curing a conductive paste having a low resistance value such as a silver paste, and the second electrode 14 and the fourth electrode 21 are electrically connected. A second terminal electrode 25 is formed by applying a conductive paste having a low resistance value such as a silver paste to the other end of the individual substrate 22 and curing it. Thereafter, as shown in FIG. 1, a nickel plating layer 26 and a tin plating layer 27 are formed on the first terminal electrode 24 and the second terminal electrode 25 in order to ensure solderability. The overvoltage protection component in Embodiment 1 is obtained.

  The overvoltage protection component according to Embodiment 1 of the present invention manufactured by the above-described manufacturing method is electrically connected between the first terminal electrode 24 and the second terminal electrode 25 during normal use (under rated voltage). Open. However, when an overvoltage such as static electricity or surge is applied, current flows through the first gap 12 and / or the second gap 19, so the overvoltage protection component according to Embodiment 1 of the present invention is By utilizing this phenomenon, an overvoltage such as static electricity or surge is bypassed to the ground to protect the electronic device from the overvoltage.

(Embodiment 2)
Hereinafter, the second and second embodiments of the present invention will be described with reference to the drawings.

  6 is a cross-sectional view of the overvoltage protection component according to Embodiment 2 of the present invention, FIGS. 7 (a) to (e), FIGS. 8 (a) to (d), FIGS. 9 (a) to (e) and FIG. (A)-(d) is a manufacturing-process figure which shows the manufacturing method of the same overvoltage protection component. 7 (a) to (e) and FIGS. 8 (a) to (d) are cross-sectional views of the individual work pieces, and FIGS. 9 (a) to (e) and FIG. (a)-(d) has shown the top view of the piece-in-process in-process item.

  Hereinafter, the manufacturing method of the overvoltage protection component in Embodiment 2 of this invention is demonstrated.

  First, as shown in FIG. 7A and FIG. 9A, the first electrode 32 is formed on the upper surface of the first insulating layer 31 made of an unfired ceramic sheet by using a screen printing method. Form with thickness. Here, the ceramic sheet constituting the first insulating layer 31 is made of, for example, a mixture of alumina powder and glass powder having a weight ratio of 40 to 60, a thickness of 20 to 50 μm, and a firing temperature of 800 to 1000 ° C. It is preferable to use a low-temperature fired ceramic, and the first electrode 32 is preferably made of a material mainly composed of gold, silver-palladium alloy, or silver. 7A and 9A show a rectangular first insulating layer having a long side of L (mm) and a short side of W (mm), which is an individual size of the overvoltage protection component. In the following description of the manufacturing process, this individual size insulating layer is used for explanation, but in the actual manufacturing process, a large number of individual size insulating layers are arranged vertically and horizontally. A sheet-like insulating layer that can be obtained is used, and is divided into individual pieces before the firing step described later.

  Next, as shown in FIGS. 7B and 9B, the first insulating layer 31 and the first electrode 32 are formed on the upper surface of the first insulating layer 31 and the upper surface of the first electrode 32. A second insulating layer 33 made of an unfired ceramic sheet having a square or rectangular opening at the center is formed so that a part of the insulating layer 33 is exposed. As with the first insulating layer 31, it is preferable to use a low-temperature fired ceramic for the ceramic sheet constituting the second insulating layer 33.

  Next, as shown in FIGS. 7C and 9C, a resin 34 is filled so as to fill the exposed portions of the first insulating layer 31 and the first electrode 32. The material of the resin 34 may be any material as long as it burns, decomposes, vaporizes, and disappears in a baking step to be described later. For example, acrylic beads that are a kind of acrylic resin can be used.

  Next, as shown in FIG. 7D and FIG. 9D, the second electrode 35 is screen-printed so as to overlap a part of the second insulating layer 33 and a part of the resin 34. And having a thickness of 2 to 5 μm. Here, similarly to the first electrode 32, the material used for the second electrode 35 is preferably a material mainly composed of gold, a silver-palladium alloy, or silver.

  Next, as shown in FIGS. 7 (e) and 9 (e), the third insulating layer 33, the resin 34, and the second electrode 35 are completely covered with a third ceramic sheet made of an unfired ceramic sheet. The insulating layer 36 is formed. Similarly to the first insulating layer 31, it is preferable to use a low-temperature fired ceramic for the ceramic sheet constituting the third insulating layer 36.

  Next, as shown in FIGS. 8A and 10A, a conductor layer 37 is formed from one end of the third insulating layer 36 to the other end. The conductor layer 37 is preferably formed thinly and uniformly using a conductive material having excellent heat resistance. In this case, the conductor layer 37 may be formed using the same material as the first electrode 32 and the second electrode 35. Alternatively, a sputtered film mainly composed of any one of titanium, nickel, tungsten, and molybdenum may be formed in a single layer or a multilayer structure. In particular, when the conductor layer 37 has a three-layer structure of a first titanium thin film, an intermediate tungsten thin film, and a second titanium thin film, the first titanium thin film ensures adhesion with the third insulating layer 36. Further, an intermediate tungsten thin film having a low resistance value and excellent heat resistance can be obtained, and further, the second titanium thin film can suppress an increase in resistance value due to oxidation of the intermediate tungsten thin film surface. The conductor layer 37 having a low resistance and excellent heat resistance can be obtained by such a three-layer structure. The conductor layer 37 is formed wider than the widths of the first electrode 32 and the second electrode 35.

  Next, as shown in FIGS. 8B and 10B, the conductor layer 37 is cut using a UV laser to form a second gap 38 having an interval of 5 to 20 μm. A third electrode 39 and a fourth electrode 40 are formed opposite to each other with a gap 38 therebetween.

  After the second gap 38 is formed, the work piece in sheet form is made into a single piece state by using a break method, a dicing method or the like, and the first insulating layer 31, the second insulating layer 33, the third The base layer 41 is formed by firing the insulating layer 36, the first electrode 32, the second electrode 35, the third electrode 39, and the fourth electrode 40 simultaneously. By performing this firing step, the resin 34 filled so as to fill the exposed portions of the first insulating layer 31 and the first electrode 32 is decomposed and vaporized to disappear, and FIG. 8C and FIG. As shown in c), a cavity 42 serving as a discharge space is formed so that the first electrode 32 and the second electrode 35 face each other with the first gap 43 therebetween. In this case, the interval between the second gaps 38 is formed to be narrower than the interval between the first gaps 43, and the third electrode 39 and the fourth electrode 40 facing each other with the second gap 38 therebetween. The width is formed wider than the widths of the first electrode 32 and the second electrode 35 facing each other with the first gap 43 therebetween.

  Finally, as shown in FIG. 8 (d) and FIG. 10 (d), at one end of the base body 41 in a single piece state so that the first electrode 32 and the third electrode 39 are electrically connected, A first terminal electrode 44 is formed by applying and curing a conductive paste having a low resistance value such as a silver paste, and the second electrode 35 and the fourth electrode 40 are electrically connected. The second terminal electrode 45 is formed by applying and curing a conductive paste having a low resistance value such as a silver paste on the other end of the substrate 41 in the individual state. Thereafter, as shown in FIG. 6, a nickel plating layer 46 and a tin plating layer 47 are formed on the first terminal electrode 44 and the second terminal electrode 45 in order to ensure solderability. The overvoltage protection component in Embodiment 2 is obtained.

  The overvoltage protection component according to Embodiment 2 of the present invention manufactured by the above-described manufacturing method is electrically connected between the first terminal electrode 44 and the second terminal electrode 45 during normal use (under rated voltage). Open. However, when an overvoltage such as static electricity or surge is applied, the current flows through the first gap 43 and / or the second gap 38, so the overvoltage protection component according to the second embodiment of the present invention is By utilizing this phenomenon, an overvoltage such as static electricity or surge is bypassed to the ground to protect the electronic device from the overvoltage.

  Next, the following tests were performed on the overvoltage protection components according to Embodiments 1 and 2 of the present invention configured as described above. As shown in FIG. 11, one terminal of the overvoltage protection component 51 according to the first and second embodiments of the present invention is grounded to the ground 52, and an electrostatic test gun 54 is attached to the electrostatic pulse application unit 53 drawn from the other terminal. An electrostatic pulse was applied in contact. The conditions for the electrostatic test were a discharge resistance of 330Ω, a discharge capacity of 150 pF, and an applied voltage of 8 kV.

  FIG. 12 is a graph showing the test results of the electrostatic test shown in FIG. 11 for the conventional overvoltage protection component and the overvoltage protection component according to the first and second embodiments of the present invention. In this graph, the horizontal axis indicates the number of repetitions of applying the electrostatic pulse, and the vertical axis indicates the peak voltage at that time. The increase in the peak voltage means that the overvoltage protection component does not operate unless static electricity of a higher voltage is applied, and thus indicates deterioration of the electrode of the overvoltage protection component.

  As is clear from FIG. 12, in the overvoltage protection component according to the first and second embodiments of the present invention, even when static electricity is repeatedly applied, the rising tendency of the peak voltage at which the overvoltage protection component operates is the conventional overvoltage protection. Since it is gentler than the parts, it can be seen that even when the application of static electricity is repeated, the peak voltage is low and the electrostatic discharge (ESD) suppression characteristics are stable. The reason is considered as follows.

  As in the first and second embodiments of the present invention described above, the first electrodes 13 and 32 and the second electrodes 14 and 35 facing each other with the first gaps 12 and 43 in the bases 22 and 41 are provided. And the third electrodes 20 and 39 and the fourth electrodes 21 and 40 facing each other with the second gaps 19 and 38 are formed on the upper surfaces of the base bodies 22 and 41, and the base bodies 22 and 41 are formed. The first electrodes 13 and 32 and the third electrodes 20 and 39 are electrically connected to each other by the first terminal electrodes 24 and 44 on one side surface, and the second electrode on the other side surface of the base member 22 and 41. In the overvoltage protection component having a configuration in which the 14 and 35 and the fourth electrodes 21 and 40 are electrically connected by the second terminal electrodes 25 and 45, when static electricity is applied to the overvoltage protection component, first, the base bodies 22 and 41. of It starts discharging from the first gap 12,43 located in the discharge space parts. When the static electricity application is repeated, the materials constituting the first electrodes 13 and 32 and the second electrodes 14 and 35 facing each other across the first gaps 12 and 43 generate heat and dissolve little by little. There is a tendency that the distance between the first gaps 12 and 43 is increased. As described above, after the application of static electricity is repeated and the interval between the first gaps 12 and 43 is increased to increase the discharge start voltage, the second gaps 19 and 38 formed on the upper surfaces of the base bodies 22 and 41 are used. However, since the overvoltage protection component continues to function simultaneously with the first gaps 12 and 43, the electric field is not concentrated only on the first gaps 12 and 43. It can reliably protect against repeated application of overvoltage. This operation principle will be described with reference to FIG.

  FIG. 13 is a diagram showing an operation principle of the overvoltage protection component in the first and second embodiments of the present invention. Generally, the discharge start voltage of a gap when an overvoltage such as static electricity or surge is applied between a pair of electrodes facing each other across the gap is determined by the degree of concentration of the electric field in the gap. It is known that the discharge start voltage increases as the start voltage increases and the electrode width increases. Therefore, when the gap interval is taken on the horizontal axis and the electrode width is taken on the vertical axis, the dischargeable region in the case where the discharge start voltage of the gap is V1, V2 (V1 <V2) is shown as a graph in FIG. The region is below the hyperbola indicated by the thick solid line and thick dotted line. In the overvoltage protection component according to Embodiments 1 and 2 of the present invention, the first gaps 12 and 43 provided in the bases 22 and 41 have a wide gap, but the electrode width is small, so that the electric field is small. The design is easy to concentrate. On the other hand, the second gaps 19 and 38 provided on the upper surfaces of the substrates 22 and 41 have a structure in which the electric field is difficult to concentrate because the gaps are narrow but the electrodes are wide.

  Here, the initial gap interval of the first gaps 12 and 43 is G1s, the gap interval after the first gaps 12 and 43 deteriorate due to repeated application of static electricity is G1e, and the initial intervals of the second gaps 19 and 38. Is G2s, the widths of the first electrodes 13, 32 and the second electrodes 14, 35 are W1, and the widths of the third electrodes 20, 39 and the fourth electrodes 21, 40 are W2. When the discharge start voltage is V1 at the initial stage of application of, as shown by point A in FIG. 13, only the first gaps 12 and 43 start discharging. After that, the discharge of the first gaps 12 and 43 is repeated to deteriorate the first gaps 12 and 43. As a result, the interval between the first gaps 12 and 43 is widened and changed from G1s to G1e. As shown at point B in FIG. 13, the discharge start voltage rises from V1 to V2. At this time, discharge is started not only in the first gaps 12 and 43 but also in the second gaps 19 and 38 as indicated by point C in FIG.

  As described above, when the first gaps 12 and 43 deteriorate due to repeated application of overvoltage such as static electricity or surge and the discharge start voltage rises from V1 to V2, not only the first gaps 12 and 43 but also Discharge also starts in the second gaps 19 and 38, and currents flow separately in the first gaps 12 and 43 and the second gaps 19 and 38, whereby only the first gaps 12 and 43 are flown. Therefore, the first electrode 13 and 32 and the second electrode 14 and 35 can be prevented from degrading, and thus the electronic device can be prevented from being repeatedly applied with an overvoltage such as static electricity or surge. It can be reliably protected.

  For the reasons described above, the overvoltage protection component according to the first and second embodiments of the present invention has the first gaps 12 and 41 inside the bases 22 and 41 as compared with the conventional overvoltage protection component as shown in FIG. The first electrodes 13 and 32 and the second electrodes 14 and 35 facing each other with the gap 43 therebetween are formed, and the third gaps facing each other with the second gaps 19 and 38 on the upper surfaces of the base bodies 22 and 41 are formed. The electrodes 20 and 39 and the fourth electrodes 21 and 40 are formed, and the first electrodes 13 and 32 and the third electrodes 20 and 39 are connected to the first terminal electrode 24 on one side surface of the bases 22 and 41. , 44, and the second electrodes 14, 35 and the fourth electrodes 21, 40 are electrically connected by the second terminal electrodes 25, 45 on the other side surfaces of the base bodies 22, 41. Toi Therefore, in the initial stage of application of overvoltage such as static electricity or surge, the discharge start voltage is low, and only the first gaps 12 and 43 provided in the cavities inside the base bodies 22 and 41 are discharged to operate the overvoltage protection component. Then, when overvoltage application is repeated thereafter and the first gaps 12 and 43 deteriorate and the discharge start voltage of the first gaps 12 and 43 rises, the overvoltage is provided on the upper surfaces of the base bodies 22 and 41. In addition, since the second gaps 19 and 38 function simultaneously with the first gaps 12 and 43 and are discharged, the overvoltage protection component continues to operate, so that the electric field is concentrated only on the first gaps 12 and 43. Thus, an overvoltage protection component capable of reliably protecting an electronic device from repeated application of an overvoltage such as static electricity or surge can be obtained.

  In the first and second embodiments of the present invention, the first electrodes 13 and 32 and the second electrodes 14 and 35 facing each other with the first gaps 12 and 43 in the bases 22 and 41 are provided. However, the present invention is not limited to this configuration. For example, as shown in FIG. 14, the process of laminating an insulating layer and an electrode is repeated to form the first gap 12 with the thickness of the base 22. A plurality of them may be formed in the direction, and even in such a configuration, the same effects as those of the first and second embodiments of the present invention can be obtained.

  In the first and second embodiments of the present invention, the third electrodes 20 and 39 and the fourth electrodes 21 and 40 facing each other across the second gaps 19 and 38 on the upper surfaces of the base bodies 22 and 41 are provided. However, the present invention is not limited to this configuration, and a plurality of second gaps 19 and 38 may be provided on the upper surface of the base member 22 or 41 in parallel or in series. Even in such a configuration, the same effects as those of the first and second embodiments of the present invention can be obtained.

  In the first and second embodiments of the present invention, when forming the first insulating layers 11 and 31, the second insulating layers 15 and 33, and the third insulating layers 17 and 36, alumina powder is used. The structure using the low-temperature fired ceramic sheet made of a mixture of 40 to 60 by weight of the glass powder has been described, but is not limited to this structure, and the first insulating layers 11 and 31 and the second insulation are not limited to this structure. Other insulating sheets such as 96 alumina, mullite, forsterite and the like may be used for the layers 15 and 33 and the third insulating layers 17 and 36. Even in such a configuration, the above-described embodiment of the present invention is implemented. The same effects as those of Embodiments 1 and 2 can be obtained.

  The overvoltage protection component according to the present invention has an effect that the electronic device can be reliably protected from repeated application of static electricity, surge, etc. In particular, an in-vehicle electronic device that requires high reliability is provided. It is useful when applied to overvoltage protection components that protect against static electricity.

Sectional drawing of the overvoltage protection component in Embodiment 1 of this invention (A)-(d) Manufacturing process figure which shows the manufacturing method of the same overvoltage protection component (A)-(d) Manufacturing process figure which shows the manufacturing method of the same overvoltage protection component (A)-(d) Manufacturing process figure which shows the manufacturing method of the same overvoltage protection component (A)-(d) Manufacturing process figure which shows the manufacturing method of the same overvoltage protection component Sectional drawing of the overvoltage protection component in Embodiment 2 of this invention (A)-(e) Manufacturing process figure which shows the manufacturing method of the same overvoltage protection component (A)-(d) Manufacturing process figure which shows the manufacturing method of the same overvoltage protection component (A)-(e) Manufacturing process figure which shows the manufacturing method of the same overvoltage protection component (A)-(d) Manufacturing process figure which shows the manufacturing method of the same overvoltage protection component Schematic diagram showing a static electricity test method for overvoltage protection components in Embodiments 1 and 2 of the present invention The figure which shows the test result of the static electricity test of the same overvoltage protection component Diagram showing the operating principle of the overvoltage protection component Sectional drawing of the overvoltage protection component in other embodiment of this invention Cross-sectional view of conventional overvoltage protection components

Explanation of symbols

11, 31 1st insulating layer 12, 43 1st gap 13, 32 1st electrode 14, 35 2nd electrode 15, 33 2nd insulating layer 16, 34 Resin 17, 36 3rd insulating layer 18 , 37 Conductor layers 19, 38 Second gap 20, 39 Third electrode 21, 40 Fourth electrode 22, 41 Base 23, 42 Cavity 24, 44 First terminal electrode 25, 45 Second terminal electrode

Claims (4)

A base, a cavity formed inside the base, and a first electrode and a second electrode facing each other across the first gap in the cavity, and a second gap on the top surface of the base And a third terminal electrode and a fourth electrode facing each other with a gap therebetween, and a first terminal electrode for electrically connecting the first electrode and the third electrode is formed on one side surface of the substrate. Furthermore, an overvoltage protection component in which a second terminal electrode for electrically connecting the second electrode and the fourth electrode is formed on the other side surface of the base. The overvoltage according to claim 1, wherein the substrate is constituted by laminating and firing low-temperature fired ceramic sheets, and the first electrode and the second electrode are made of a material mainly composed of gold, silver-palladium alloy, or silver. Protective parts. Forming a first electrode and a second electrode so as to be opposed to the upper surface of the first insulating layer with a first gap therebetween; and in the vicinity of the first gap of the first insulating layer A step of forming a second insulating layer so as to cover a portion other than the cavity forming portion, a step of filling the cavity forming portion with a resin, and a step of completely covering the second insulating layer and the resin. And forming a second gap by cutting the conductor layer formed on the upper surface of the third insulating layer with a laser so as to face each other across the second gap. The step of forming the third electrode and the fourth electrode, and the third insulating layer from the first insulating layer and the fourth electrode from the first electrode are simultaneously fired to fill the cavity forming portion. The resin is lost, and a cavity is formed in the vicinity of the first gap. Forming a first terminal electrode by applying a conductive paste so that the first electrode and the third electrode are electrically connected, and the second electrode and the fourth electrode. And a step of forming a second terminal electrode by applying a conductive paste so that the electrodes are electrically connected to each other. Forming a first electrode on an upper surface of the first insulating layer and forming one second insulating layer on the first insulating layer so as not to cover a part of the first electrode; Forming a second insulating layer on the first electrode so as to face the second insulating layer with a first gap on the first electrode; and the first insulating layer. A step of filling the cavity forming portion in the vicinity of the first gap not covered with the second insulating layer with a resin, and at least a part of the resin overlaps both the second insulating layers; Forming the second electrode as described above, forming the third insulating layer so as to completely cover the second insulating layer and the second electrode, and forming an upper surface on the third insulating layer. By cutting the formed conductor layer with a laser to form a second gap, this second gap is reduced. Forming the third electrode and the fourth electrode facing each other, and simultaneously firing the third insulating layer from the first insulating layer and the fourth electrode from the first electrode to form the cavity Disposing the resin filled in the forming portion to form a cavity in the vicinity of the first gap, and applying a conductive paste so that the first electrode and the third electrode are electrically connected Forming a first terminal electrode, and applying a conductive paste so that the second electrode and the fourth electrode are electrically connected to each other to form a second terminal electrode. Manufacturing method of overvoltage protection component provided.

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