JP2010232246A - Overvoltage protection component - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an overvoltage protection component which can protect an electronic component with low resistance to an overvoltage and has a low discharge start voltage. <P>SOLUTION: The overvoltage protection component is provided with a substrate 1, a pair of a first discharge electrode 2 and a second discharge electrode 3 which are formed on the substrate 1 with a gap therebetween, conducting powder 4 formed not to be electrically short-circuited in a gap between a pair of the first discharge electrode 2 and the second discharge electrode 3 on the substrate 1 and an overvoltage protection object 5 which is formed in the gap between a pair of the first discharge electrode 2 and the second discharge electrode 3 on the substrate 1 and whose resistance value drops at the time of applying overvoltage. <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 on the same plane with a gap therebetween, and the two electrodes are insulated during normal operation, but two overvoltages are applied when overvoltage is applied. Have a function of discharging between the electrodes (see Patent Document 1).

  Moreover, what was equipped with the overvoltage protection material which consists of resin and metal powder between the gaps of two electrodes is also known (refer patent document 2).

In addition, the cover is formed of a mixture of a conductor and an insulator without shortening the distance between the pair of discharge electrodes, the start of discharge is performed through the conductor constituting the cover, and the main discharge is performed between the discharge electrodes. An overvoltage protection component is also known (see Patent Document 3).
JP 2004-14437 A JP 2007-281112 A 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 the decrease in the voltage value allowed by the electronic component, the voltage at which the overvoltage protection component starts to flow electricity, that is, the decrease in the discharge start voltage (trigger voltage) is required. One means for reducing the discharge start voltage is to shorten the gap distance between the two electrodes.

  However, shortening the gap distance has a tradeoff with manufacturing accuracy, and there is a limit to the method of reducing the discharge start voltage by shortening the gap distance.

  Further, as another means for reducing the discharge start voltage, the structure as in Patent Document 3 is adopted, and the discharge is not started between the gaps of the pair of discharge electrodes, but the space including the pair of discharge electrodes. A method is also conceivable in which a lid is formed of a mixture of an insulator and a conductor and discharge is generated between the conductors of the lid. However, in this case, since the path in which the discharge occurs when starting the discharge is not the gap between the pair of discharge electrodes but the path through the lid, the discharge path becomes longer, and the discharge start voltage is accordingly increased. The demand for reducing the discharge start voltage has not necessarily been met.

  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 having a low discharge start voltage that can protect an electronic component having a low tolerance to overvoltage.

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

  The invention according to claim 1 is formed so as not to be electrically short-circuited between the base, the pair of electrodes formed on the base with a gap therebetween, and the gap between the pair of electrodes on the base. It has conductor powder and an overvoltage protector which is formed between the pair of electrodes on the substrate and whose resistance value decreases when an overvoltage is applied.

  According to this configuration, the invention according to claim 1 lowers the impedance at the time of overvoltage application due to the presence of the discharge path via the conductive powder formed between the gaps in addition to the discharge path via the overvoltage protector. Therefore, there is an effect that the discharge start voltage can be reduced.

  The invention according to claim 2 is an embodiment in which an adhesive layer for adhering the conductive powder to the base is added between the base and the conductive powder. It has the effect that it can be made to adhere to.

  As described above, since the overvoltage protection component of the present invention can reduce the discharge start current due to the presence of the conductive powder formed between the gaps, it can protect electronic components and electronic circuits that are less resistant to overvoltage. It has the effect.

  Hereinafter, the invention described in claims 1 and 2 of the present invention will be described.

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

  The substrate 1 is made of an insulator and has a plate shape. The substrate 1 is required to have an insulating property and not to be damaged even if a discharge occurs on the surface thereof, and is preferably made of an alumina substrate having excellent heat resistance and thermal shock resistance.

  The first discharge electrode 2 and the second discharge electrode 3 constitute a pair of electrodes, and both are formed on the substrate 1 with a gap therebetween. The material of the first discharge electrode 2 and the second discharge electrode 3 is preferably excellent in conductivity and heat resistance, and is preferably a metal. Among metals, copper, silver, gold, palladium, or an alloy thereof is used if conductivity is important, and tungsten or molybdenum is preferable if heat resistance is important.

  The conductor powder 4 is formed in the gap between the first discharge electrode 2 and the second discharge electrode 3 on the substrate 1. As the material of the conductor powder 4, metal powder is preferable in terms of heat resistance and conductivity, and materials suitable for the first discharge electrode 2 and the second discharge electrode 3 can be used. The material of the conductor powder 4 may be the same as that of the first discharge electrode 2 and the second discharge electrode 3 or may be different.

  The overvoltage protector 5 covers the conductor powder 4 and is formed so as to overlap a part on the first discharge electrode 2 and the second discharge electrode 3. The overvoltage protector 5 normally functions as an insulator, but functions as a good conductor when an overvoltage is applied. Specifically, what mixes the conductor powder which covered the surface with the insulating film in resin, such as silicone, is mentioned. As such a conductor powder, one obtained by oxidizing the surface of aluminum can be used, but is not limited thereto.

  The protective layer 6 covers at least the overvoltage protector 5 and has a function of protecting the overvoltage protector 5 from an environment such as mechanical shock and humidity. Polyamide or epoxy resin is preferably used. An intermediate layer made of a silicone resin or the like having a function as a buffer layer may be used between the protective layer 6 and the overvoltage protector 5.

  The first terminal electrode 7 is formed so as to overlap with the end surface of the substrate 1, a part of the back surface, and a part of the first discharge electrode 2 on the top surface of the substrate 1, and is electrically connected to the first discharge electrode 2. is doing. The 1st terminal electrode 7 can be made into the structure which formed the nickel plating layer in the good conductors, such as copper, and also formed the tin plating layer.

  Similarly, the second terminal electrode 8 is also formed so as to overlap with the end face of the substrate 1, a part of the back surface, and a part of the second discharge electrode 3 on the top surface of the substrate 1. Connected. The second discharge electrode 3 can be formed by forming a nickel plating layer on a good conductor such as copper and further forming a tin plating layer.

  The overvoltage protection component 9 has the above configuration.

  A method for manufacturing the overvoltage protection component 9 configured as described above will be described below.

  FIG. 2 is a front sectional view showing a method of manufacturing an overvoltage protection component in one embodiment of the present invention, and FIG. 3 is a plan view of the same.

  As shown in FIGS. 2A and 3A, the base 1 is first prepared.

  Next, as shown in FIGS. 2 (b) and 3 (b), conductor powder is formed in a portion corresponding to a gap between a first discharge electrode 2 and a second discharge electrode 3 (to be described later) substantially at the center of the substrate 1. 4 is attached. As a specific manufacturing method, it can be made by applying a mixture of the conductor powder 4 and a resin paste such as acrylic and baking it. Further, an adhesive layer such as glass is formed in advance between the gap between the first discharge electrode 2 and the second discharge electrode 3, and a mixture of the conductor powder 4 and the resin paste is applied thereon. And it may be a method of firing thereafter. In this case, the adhesion of the conductor powder 4 becomes more reliable. As the substance to be the adhesive layer, a substance containing at least one of glass, bismuth oxide, lead oxide, silicon oxide, alkaline earth metal oxide, and alkali oxide is preferable. Moreover, you may adhere the conductor powder 4 by methods, such as coating.

  Next, as shown in FIGS. 2C and 3C, the first discharge electrode 2 and the second discharge electrode 3 are formed on the substrate 1. These can be formed by printing and baking, but may be formed by a thin film method.

  Next, as shown in FIGS. 2 (d) and 3 (d), an overvoltage protector 5 is applied on the first discharge electrode 2 and part of the second discharge electrode 3 and the conductor powder 4 by printing. To do. The overvoltage protector 5 is not necessarily formed on the first discharge electrode 2 and the second discharge electrode 3, but between the first discharge electrode 2 and the second discharge electrode 3. Need to form.

  Next, as shown in FIGS. 2 (e) and 3 (e), a protective layer 6 is formed so as to cover the overvoltage protector 5 and to overlap the first discharge electrode 2 and a part of the second discharge electrode 3. To do. Since the protective layer 6 is formed so as to cover the entire overvoltage protector 5, the protective layer 6 is formed so as to overlap a part of the first discharge electrode 2 and the second discharge electrode 3. 2 and the entire surface of the second discharge electrode 3, there is no part for electrical connection with the first terminal electrode 7 and the second terminal electrode 8, so that only a part of the electrode is overlapped. Forming.

  Next, as shown in FIGS. 2 (f) and 3 (f), the first terminal electrode 7 so as to be electrically connected to the end surface and part of the back surface of the substrate 1 and the first discharge electrode 2. The second terminal electrode 8 is formed so as to be electrically connected to the second discharge electrode 3. The first terminal electrode 7 and the second terminal electrode 8 are printed with a paste made of a good conductor such as copper and fired. Then, a nickel plating layer is formed on the surface by electrolytic plating, and then tin plating is performed. A method of forming the layer by electrolytic plating can be employed.

  In order to manufacture efficiently, a large substrate is used, and a plurality of first discharge electrodes 2, second discharge electrodes 3, conductor powder 4, overvoltage protector 5 and protective layer 6 are formed on the large substrate. The first terminal electrode 7 and the second terminal electrode 8 are divided into strips so that the side surfaces for forming the first terminal electrode 7 and the second terminal electrode 8 are exposed. The base electrode may be formed and then divided into individual pieces, and a nickel plating layer and a tin plating layer may be formed on the base electrodes of the first terminal electrode 7 and the second terminal electrode 8. .

  The operation of the overvoltage protection component 9 configured and manufactured as described above will be described below. The overvoltage protection component 9 is electrically connected in parallel with an electronic component or the like to be protected from overvoltage. Therefore, one of the first discharge electrode 2 and the second discharge electrode 3 is connected to the applied voltage side, and the other is connected to the ground side.

  In a normal use state, the resistance value between the first discharge electrode 2 and the second discharge electrode 3 is extremely high, and the overvoltage protection component 9 functions as an insulator. Therefore, in normal times, a current flows through the electronic component to be protected from overvoltage. On the other hand, when an overvoltage is applied, discharge is started by discharging between the conductor powders 4 adhered between the gaps of the first discharge electrode 2 and the second discharge electrode 3. When this discharge is started, electricity flows also in the overvoltage protector 5, and the overvoltage protection component 9 exhibits a function as a conductor. As a result, the overvoltage causes the overvoltage without flowing through the electronic component to be protected. Since it passes through the protective component 9 and flows to the ground, the electronic component can be protected.

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

  In the overvoltage protection component 9 of the present invention, the conductor powder 4 is adhered between the gaps of the first discharge electrode 2 and the second discharge electrode 3, and the presence of the conductor powder 4 makes it easy for discharge to occur. Explaining this point, the portion to which the conductor powder 4 is adhered is not smooth and has irregularities, and the overvoltage protector 5 enters the portion. Therefore, in this portion, the conductor powder 4 is present, It becomes easier to start the discharge than the portion composed only of the overvoltage protector 5 where the conductor powder 4 does not exist. For this reason, first, the tip of the first discharge electrode 2 and the second discharge electrode are passed through the conductor powder 4 at a lower voltage than the case where the conductor powder 4 does not exist and only the overvoltage protector 5 is configured. The discharge is started between the three tip portions. Once the discharge is started, the discharge between the tip portion of the first discharge electrode 2 and the tip portion of the second discharge electrode 3 is performed via the overvoltage protector 5. Since both the discharge at the start of discharge and the discharge of the main discharge are discharges between the tip of the first discharge electrode 2 and the tip of the second discharge electrode 3, the main discharge is started from the state of the discharge start. Smooth transition to discharge.

  As described above, the overvoltage protection component 9 of the present invention can pass electricity through the overvoltage protection component 9 even when a large current due to the overvoltage flows, and can protect the electronic component from a lower overvoltage. Become.

  In addition, as an average particle diameter of the conductor powder 4, about 0.1-10 micrometers is preferable.

  Furthermore, the component ratio of the conductor powder 4 and the resin paste when the conductor powder 4 is formed by the printing method is the distance between the conductor powder 4 adhered between the first discharge electrode 2 and the second discharge electrode 3. However, it may be determined as appropriate according to the assumed discharge start voltage. The same applies when the conductor powder 4 is adhered by a method such as painting, which is useful for electronic parts used in electronic equipment.

  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 Front sectional view showing the manufacturing method of the overvoltage protection component Plan view of FIG.

DESCRIPTION OF SYMBOLS 1 Base | substrate 2 1st discharge electrode (a pair of electrodes)
3 Second discharge electrode (a pair of electrodes)
4 Conductor powder 5 Overvoltage protector 6 Protective layer 7 First terminal electrode 8 Second terminal electrode 9 Overvoltage protection component

Claims (2)

A substrate;
A pair of electrodes formed with a gap on the substrate;
Conductive powder formed so as not to be electrically short-circuited between the pair of electrodes on the base at a normal time,
An overvoltage protector that is formed between the pair of electrodes on the base and has a resistance value that decreases when an overvoltage is applied;
Overvoltage protection component with. The overvoltage protection component according to claim 1, wherein an adhesive layer for adhering the conductive powder to the base is added between the base and the conductive powder.

Images