JP4292935B2 - Chip-type surge absorber and manufacturing method thereof - Google Patents

Description

  The present invention relates to a chip-type surge absorber used for protecting various devices from surges and preventing accidents, and a method for manufacturing the same.

  Portions where electronic devices for communication devices such as telephones, facsimiles, modems, etc. are connected to communication lines, power lines, antennas, CRT drive circuits, etc., portions that are susceptible to electrical shock due to abnormal voltage (surge voltage) such as lightning surge or static electricity A surge absorber is connected to prevent damage due to thermal damage or ignition of an electronic device or a printed circuit board on which the device is mounted due to an abnormal voltage.

  Conventionally, for example, a chip-type surge absorber using a surge absorbing element having a micro gap has been proposed. The surge absorber includes a pair of discharge electrodes disposed on the surface of an insulating substrate so as to face each other through so-called micro gaps and different edges, and a pair of discharge electrodes including an adhesive having a glass material. A lid having a peripheral edge bonded to an outer peripheral portion of an insulating substrate including a base end; and a pair of terminal electrodes arranged to be electrically connected to the pair of discharge electrodes at both ends of the insulating substrate and the lid. Discharge type surge absorber. (For example, refer to Patent Document 1).

In recent years, in such a chip type surge absorber, it has been desired to reduce the discharge start voltage at the discharge electrode, and since the discharge electrode is thin, the electric field tends to concentrate near the tip of the microgap. It is known that the starting voltage decreases.
JP 2001-35634 A (FIG. 1)

  However, the following problems remain in the conventional surge absorber. That is, in a conventional surge absorber, when a thin discharge electrode is formed by sputtering or chemical vapor deposition (hereinafter abbreviated as CVD), the formed discharge electrode is a metal film or a compound corresponding thereto. Therefore, when the discharge space is formed by adhering the lid through the adhesive having the glass material on the outer peripheral portion of the insulating substrate including the discharge electrode, the wettability between the discharge electrode and the adhesive is poor, and It was difficult to seal because the coefficients of thermal expansion differed greatly.

  On the other hand, since the discharge electrode is directly joined to the terminal electrode, when the discharge electrode is a thin film, the contact area between the discharge electrode and the terminal electrode is reduced. When a surge life test is performed, a current flows through the contact point between the discharge electrode and the terminal electrode, but because the contact area is small, the current density at the contact point increases and heat is generated. There is a possibility that good electrical contact with the terminal electrode cannot be obtained.

  Although the discharge start voltage can theoretically be reduced by reducing the thickness of the discharge electrode, the discharge electrode is more likely to be oxidized when the discharge space is actually formed as the discharge electrode becomes thinner. Therefore, there has been a problem that the discharge start voltage increases due to the change of the discharge electrode.

  In addition, even when a thin discharge electrode is formed by sputtering, the discharge electrode evaporates and is damaged due to heat and strain during discharge when a surge of higher energy is repeatedly applied, so that it does not have a long life. There is.

  The present invention has been made in view of the above-described problems, and can be easily sealed, can prevent damage at contact points, and can suppress deterioration of the discharge electrode. An object is to provide a surge absorber and a method for manufacturing the same.

  The present invention employs the following configuration in order to solve the above problems. That is, the chip-type surge absorber of the present invention includes an insulating substrate formed of an insulating material, a pair of connection electrodes that are arranged opposite to each other on one surface of the insulating substrate, and are formed up to different edges. The insulation including a pair of discharge electrodes connected to each of the pair of connection electrodes and arranged to face each other via a discharge gap, and a base end portion of the pair of connection electrodes via an adhesive having a glass material The insulating substrate is connected to the box-shaped lid that is fixed to the outer periphery of the substrate and forms a discharge space above the insulating substrate, and the pair of connection electrodes exposed at the edge. In the chip type surge absorber provided with a pair of terminal electrodes arranged at both ends of the metal, the connection electrode is formed of a material containing a glass material in a metal.

  Also, the manufacturing method of the chip-type surge absorber according to the present invention includes the formation of a connection electrode that forms a pair of connection electrodes that are opposed to each other on one surface of the insulating substrate and extend to different edges of the insulating substrate. A discharge electrode forming step of forming a pair of discharge electrodes facing each other via a discharge gap and connected to each of the pair of connection electrodes; and the pair of connection electrodes via an adhesive having a glass material A box-shaped lid is fixed on the outer periphery of the insulating substrate including the base end of the insulating substrate, and a pair of both ends of the insulating substrate is connected to the pair of connection electrodes exposed at the edge. In the manufacturing method of the chip-type surge absorber having the sealing step for forming the terminal electrode, the connection electrode forming step forms the connection electrode with a material containing a glass material in the metal.

  According to the chip type surge absorber and the manufacturing method according to the present invention, when the connection electrode and the lid are bonded using an adhesive having a glass material, the connection electrode is made of a material containing a glass material in a metal. Therefore, the wettability with the adhesive is improved. Further, the difference in thermal expansion coefficient between the adhesive and the connection electrode can be reduced by adjusting the amount of the glass material contained in the connection electrode. Therefore, the sealing property between the insulating substrate and the connection electrode and the lid is improved, and a discharge space having good airtightness can be easily obtained.

In the chip type surge absorber according to the present invention, it is preferable that the discharge electrode is formed of only a conductive material.
In the method for manufacturing a chip-type surge absorber according to the present invention, it is preferable that the discharge electrode forming step forms the discharge electrode formed of only a conductive material.
According to the chip-type surge absorber and the manufacturing method according to the present invention, since the discharge electrode is composed of only a conductive material without a mixture of glass and binder, the conductive material constituting the discharge electrode is always Since it exists at the tip of the discharge gap, the discharge start voltage can be lowered.

Moreover, in the chip-type surge absorber according to the present invention, it is preferable that the film thickness of the discharge electrode formed by sputtering is 0.5 μm or more and 5 μm or less.
According to the present invention, since the thickness of the discharge electrode is 0.5 μm or more, when the discharge space is formed, the surface of the discharge electrode is oxidized, and the discharge start voltage generated by the fact that the conductive material does not appear on the surface is generated. The rise can be suppressed.
In addition, since the film thickness is 5 μm or less, a significant deterioration of the insulation resistance value due to the discharge being performed only on the discharge gap side of the pair of discharge electrodes when absorbing the surge is prevented. Therefore, the life of the surge absorber can be extended by spreading the discharge to the entire discharge electrode without staying at the tip end side of the discharge electrode. Moreover, if it is 5 micrometers or less, the effect of electric field concentration is large and the discharge start voltage can be lowered.

In the chip type surge absorber according to the present invention, it is preferable that the connection electrode is formed thicker than the discharge electrode.
According to the present invention, since the contact area between the connection electrode and the terminal electrode can be increased by increasing the thickness of the connection electrode, the heat generation at the contact point between the connection electrode and the terminal electrode is suppressed in the surge life test. In addition, it is possible to prevent breakage at the connection location. At this time, the thickness of the connection electrode is preferably 5 μm or more.

Moreover, in the manufacturing method of the chip type surge absorber according to the present invention, the connection electrode forming step forms a connection electrode by a screen printing method, and the discharge electrode formation step forms a discharge electrode by a sputtering method. preferable.
According to the present invention, since the thick connection electrode can be easily formed by the screen printing method, the contact area between the connection electrode and the terminal electrode can be easily increased. Therefore, when a surge life test is performed in the same manner as described above, damage to the connection portion between the connection electrode and the terminal electrode can be prevented.
Further, since a thin discharge electrode having good adhesion to an insulating substrate can be easily formed by sputtering, the discharge start voltage can be reduced. Furthermore, the film thickness can be easily controlled and the thickness is reduced, so that when the surge is absorbed, the discharge spreads over the entire discharge electrode, thereby extending the life of the chip-type surge absorber.

Moreover, in the manufacturing method of the chip type surge absorber according to the present invention, the connection electrode forming step forms a connection electrode by a screen printing method, and the discharge electrode formation step forms a discharge electrode by a chemical vapor deposition method. Is preferred.
According to the present invention, since a thin discharge electrode can be easily formed by the CVD method, the discharge start voltage between the pair of discharge electrodes can be lowered and the life of the chip-type surge absorber can be extended as described above. it can. In addition, compared with the case where the discharge electrode is formed by sputtering, it is possible to form a discharge electrode that has better adhesion to an insulating substrate, a high melting point, and high strength.

  According to the chip-type surge absorber of the present invention, the connection electrode and the adhesive can have good wettability and the difference in thermal expansion coefficient can be reduced, so that the insulating substrate and the connection electrode and the lid are sealed. Wearability can be improved. Therefore, it is possible to stably manufacture a chip-type surge absorber with good discharge space airtightness.

Hereinafter, an embodiment of a chip-type surge absorber according to the present invention will be described with reference to FIGS. 1 and 2.
As shown in FIGS. 1 and 2, the chip-type surge absorber 1 according to the present embodiment is a discharge-type surge absorber using a so-called microgap, and includes an insulating substrate 11 and a surface 11 </ b> A of the insulating substrate 11. A pair of connection electrodes 12 and 13 which are arranged opposite to each other and formed to different edges, and a pair of discharge electrodes 15 which are connected to the pair of connection electrodes 12 and 13 and are arranged to face each other via a discharge gap 14. 16 and a box-like shape that is fixed to the outer peripheral portion of the insulating substrate 11 including the base end portions of the pair of connection electrodes 12 and 13 via the adhesive 17 to form a discharge space 18 on the insulating substrate 11. A lid 19 and a pair of terminal electrodes 21 and 22 disposed at both ends of the insulating substrate 11 so as to be electrically connected to the pair of connection electrodes 12 and 13 exposed at the edge portions are provided.

  The insulating substrate 11 and the lid 19 are made of an insulating material such as alumina, and the surface of the lid 19 facing the one surface 11A of the insulating substrate 11 is formed of the lid 19 and the one surface 11A. A recess 19A for forming the discharge space 18 is provided therebetween. The insulating substrate 11 and the lid 19 are brought into contact with each other via an adhesive 17 so as to surround the entire circumference of the recess 19A, and the discharge space 18 formed therebetween is hermetically sealed.

Here, in the discharge space 18, in order to stabilize the discharge characteristics of the chip-type surge absorber 1 while keeping the discharge conditions between the discharge electrodes 15 and 16 constant, together with an inert gas such as Ar (argon), for example. It is sealed.
The surfaces of the terminal electrodes 21 and 22 are plated.

The connection electrodes 12 and 13 are made of a material containing a glass material in silver so as to reduce the difference in thermal expansion coefficient with the insulating substrate 11 and improve the wettability with the adhesive 17. The thickness is set to 5 to 10 μm by the screen printing method.
The discharge electrodes 15 and 16 are made of, for example, a conductive material such as Ti, have a thickness of 0.5 μm to 5 μm by a sputtering method, and are formed by laser cutting at the center.

A manufacturing method of the chip type surge absorber 1 of the present invention configured as described above will be described below.
First, a connection electrode formation process is performed. As shown in FIG. 3A, a pair of connection electrodes 12 and 13 having a film thickness of 5 to 10 μm are formed on one surface 11A of an insulating substrate 11 made of alumina by a screen printing method. Here, the pair of connection electrodes 12 and 13 are made of a material containing 5% to 10% of a glass material by volume in silver having conductivity, and are formed up to different edges of the insulating substrate 11. .

Next, a discharge electrode forming step is performed. As shown in FIG. 3B, this is connected to each of a pair of connection electrodes 12 and 13 having a film thickness of 0.5 to 5 μm by sputtering using a mask having an opening at a predetermined position. Discharge electrodes 15 and 16 to be formed are formed. Here, the discharge electrodes 15 and 16 are formed of only a conductive material such as Ti.
Thereafter, as shown in FIG. 3C, a discharge gap 14 is formed by laser cutting in the center of the discharge electrodes 15 and 16.

Subsequently, a sealing process is performed. In this process, as shown in FIG. 3D, an adhesive 17 having a glass material is formed around the insulating substrate 11 by printing. Thereafter, as shown in FIGS. 3E and 3F, for example, in an atmosphere of an inert gas such as Ar, the lid body 19 formed of an insulating material is attached to the pair of connection electrodes 12, 13 and A pair of discharge electrodes 15 and 16 are covered with an adhesive 17 on the insulating substrate 11 so as to cover the pair of discharge electrodes 15 and 16. At this time, an inert gas is sealed in the formed discharge space 18.
Further, as shown in FIG. 3G, for example, Ag and a glass material are formed by a dipping method so as to be electrically connected to the pair of exposed connection electrodes 15 and 16 at both ends of the insulating substrate 11 and the lid 19. The terminal electrodes 21 and 22 are formed by adhering the paste composed of the above. Then, the surface of the terminal electrodes 21 and 22 is plated.

In the chip type surge absorber 1 configured as described above, a material containing a glass material in the metal is used for the connection electrodes 12 and 13 formed on the insulating substrate 11 in the connection electrode forming step. Therefore, the wettability with the adhesive 17 is improved, the adhesiveness between the connection electrodes 12 and 13 and the adhesive 17 is improved in the sealing process, and the discharge space 18 having good airtightness can be easily obtained.
Further, since the thick connection electrodes 12 and 13 are easily formed by the screen printing method, the contact area between the connection electrodes 12 and 13 and the terminal electrodes 21 and 22 can be increased, and a surge life test was performed. In this case, the current density flowing at the contact portion between the connection electrodes 12 and 13 and the terminal electrodes 21 and 22 is reduced to prevent the contact portions between the connection electrodes 12 and 13 and the terminal electrodes 21 and 22 from being damaged by heat generated.

  In addition, in the discharge electrode forming step, the discharge electrodes 15 and 16 are formed by sputtering, so that a thin film having good adhesion to the insulating substrate 11 can be easily formed. Moreover, since the film thickness of the discharge electrodes 15 and 16 is 0.5 μm or more and 5 μm or less, a portion where the discharge electrodes 15 and 16 are not oxidized remains in the sealing step, and the discharge start voltage can be lowered. Further, since the discharge electrodes 15 and 16 are thin with a thickness of 5 μm or less, the discharge progresses to the whole, and the deterioration of the insulation resistance value can be suppressed and the life of the chip-type surge absorber 1 can be extended.

Next, another method for manufacturing the surge absorber 1 of the present invention will be described. In the above embodiment, the discharge electrodes 15 and 16 are formed by the sputtering method. However, in this embodiment, the discharge electrodes 15 and 16 made of only a conductive material such as TiN are formed by the CVD method.
By forming the discharge electrodes 15 and 16 by the CVD method, a thin film having better adhesion to the insulating substrate 11 and higher melting point and strength than the sputtering method can be obtained. Therefore, it is possible to provide a chip-type surge absorber that has a longer life.

In addition, this invention is not limited to the said embodiment, A various change can be added in the range which does not deviate from the meaning of this invention.
For example, conductive materials used for the discharge electrode and the connection electrode are Ag, Ag / Pd alloy, SnO ₂ , Al, Ni, Cu, Ti, TiN, TiC, Ta, W, SiC, BaAl, Nb, Si, C, You may be comprised by electroconductive substances, such as Ag / Pt alloy, ITO, Ru, or these mixtures.
Further, the volume ratio of the glass material contained in the connection electrode may be appropriately changed within a range of 1% to 50% in accordance with the material of the insulating substrate and the thermal expansion coefficient.
The terminal electrode may be made of a conductive metal such as Ag, Pt, Au, Pd, Sn, or Ni, or a mixture of these materials with a glass material or a resin material added.
Further, the atmosphere at the time of sealing, that is, the inert gas inside is determined according to the discharge characteristics, for example, N ₂ , Ne, He, Xe, H ₂ , SF ₆ , CF ₄ , C ₂ F ₆ , C ₃ F ₈ , CO ₂ , and a mixed gas thereof may be used.

  In the present invention, a material containing a glass material is used for the connection electrode. In addition, when the glass material is not contained in the connection electrode, the above-described improvement in the sealing property cannot be obtained, but it can be easily formed into a thick film by forming the connection electrode by a screen printing method. A thin film can be easily formed by forming a discharge electrode by sputtering or CVD. Therefore, the contact area between the connection electrode and the terminal electrode can be increased, and breakage of the connection location can be suppressed.

Next, the chip type surge absorber according to the present invention will be specifically described with reference to examples.
First, as an example, the connection electrodes 12 and 13 having a thickness of 5 μm are formed using a material composed of Ag and a glass material, and the discharge electrodes 15 and 16 having a thickness of 1 μm are formed using Ti. The chip type surge absorber 1 according to the above embodiment was manufactured. The glass material is contained by 5% by volume.
Further, as a comparative example, the connection electrodes 12 and 13 are not provided, and the discharge electrodes 15 and 16 having a thickness of 1 μm formed by using Ti as in the embodiment are directly connected to the terminal electrodes 21 and 22. A chip type surge absorber was manufactured.

The sealing rate indicating the probability of obtaining good hermeticity was obtained by evaluating the hermeticity of the discharge space 18 by bubble leak check for 100 of each of these examples and comparative examples. The results are shown in Table 1.
Further, static electricity of 500 pF, 0Ω, and 25 kV was applied to the chip type surge absorbers of the example and the comparative example in which good airtightness was obtained, respectively, and the connection resistance value at the connection point with the terminal electrodes 21 and 22 with respect to the number of times of application was determined. It was measured. The result is shown in FIG. In FIG. 4, the junction resistance value of the conventional example is 10 ¹² Ω, but 10 ¹² Ω is the upper limit of measurement, which is actually a value higher than that.

As shown in Table 1, according to the present invention, it was confirmed that the discharge space 18 having good airtightness can be easily obtained by providing the connection electrodes 12 and 13 containing the glass material.
Further, as shown in FIG. 4, it was confirmed that by providing the terminal electrodes 12 and 13, the bondability with the terminal electrodes 12 and 13 was significantly improved.

  Next, the discharge electrodes 15 and 16 in the chip-type surge absorber 1 according to the above embodiment are formed by sputtering, and the film thickness of the discharge electrodes 15 and 16 is changed from 0.2 μm to 10 μm, and discharge starts at each film thickness. The insulation resistance value when a voltage and static electricity of 500 pF, 0Ω, and 25 kV were applied 100 times was measured. The results are shown in FIGS.

  As shown in FIG. 5, it was confirmed that when the thickness of the discharge electrodes 15 and 16 is 0.5 μm or more, the discharge start voltage is stabilized because the discharge electrodes 15 and 16 are not easily affected by oxidation or the like in the encapsulation process. In addition, as shown in FIG. 6, it was confirmed that when the thickness of the discharge electrodes 15 and 16 is 5 μm or less, the discharge spreads over the entire discharge electrodes 15 and 16, thereby suppressing the deterioration of the insulation resistance value. From these, it was confirmed that by setting the thickness of the discharge electrodes 15 and 16 to 0.5 μm to 5 μm, the discharge start voltage can be lowered and the life of the chip-type surge absorber 1 can be extended.

  Next, a chip type surge absorber having discharge electrodes 15 and 16 composed only of TiN by a CVD method is manufactured, and the film thickness of the discharge electrode is changed from 0.2 μm to 5 μm. The insulation resistance value when static electricity of 500 pF, 0Ω, and 25 kV was applied 100 times was measured. The result is shown in FIG.

  As shown in FIG. 7, the adhesion to the insulating substrate is higher by the CVD method, and the discharge electrode having a high melting point and the higher strength is formed, compared with the case where the discharge electrode is formed by the sputtering method. It was confirmed that deterioration of the insulation resistance value was suppressed and the life was extended.

It is a perspective view showing a chip type surge absorber in one embodiment concerning the present invention. It is an axial sectional view showing a chip type surge absorber in one embodiment concerning the present invention. It is a perspective view which shows the manufacturing method of the chip type surge absorber in one Embodiment concerning this invention in process order. It is a graph which shows the relationship between the frequency | count of surge application in Example 1 concerning this invention, and junction resistance value. It is a graph which shows the relationship between the film thickness of the discharge electrode and discharge start voltage in Example 2 concerning this invention. It is a graph which shows the relationship between the film thickness of the discharge electrode in Example 2 concerning this invention, and an insulation resistance value. It is a graph which shows the relationship between the film thickness of the discharge electrode in Example 3 concerning this invention, and an insulation resistance value.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Chip type surge absorber 11 Insulating substrate 12, 13 Connection electrode 14 Discharge gap 15, 16 Discharge electrode 17 Adhesive 18 Discharge space 19 Cover body 21, 22 Terminal electrode

Claims (8)

An insulating substrate formed of an insulating material, a pair of connection electrodes disposed on one surface of the insulating substrate so as to face each other and different edges, and connected to each of the pair of connection electrodes A pair of discharge electrodes arranged opposite to each other via a discharge gap, and an insulating member fixed on the outer peripheral portion of the insulating substrate including a base end portion of the pair of connection electrodes via an adhesive having a glass material. A pair of terminal electrodes disposed at both ends of the insulating substrate so as to be electrically connected to the pair of connection electrodes exposed at the edge portion; In a chip-type surge absorber with
A chip-type surge absorber, wherein the connection electrode is formed of a material containing a glass material in a metal.   The chip-type surge absorber according to claim 1, wherein the discharge electrode is formed of only a conductive material.   3. The chip-type surge absorber according to claim 1, wherein a film thickness of the discharge electrode formed by a sputtering method is 0.5 μm or more and 5 μm or less.   The chip-type surge absorber according to any one of claims 1 to 3, wherein the connection electrode is formed thicker than the discharge electrode. A connection electrode forming step of forming a pair of connection electrodes that are opposed to each other on one surface of the insulating substrate and extend to different edges of the insulating substrate;
A discharge electrode forming step of forming a pair of discharge electrodes opposed to each other via a discharge gap and connected to each of the pair of connection electrodes;
The pair of connection electrodes exposed at the edge by fixing a box-like lid on the outer peripheral portion of the insulating substrate including the base ends of the pair of connection electrodes via an adhesive having a glass material In a method of manufacturing a chip-type surge absorber having a sealing step of forming a pair of terminal electrodes at both ends of the insulating substrate so as to be electrically connected to each other,
The method for manufacturing a chip-type surge absorber, wherein the connection electrode forming step forms the connection electrode with a material containing a glass material in a metal.   6. The method for manufacturing a chip-type surge absorber according to claim 5, wherein the discharge electrode forming step forms the discharge electrode formed of only a conductive material. The connection electrode forming step forms the connection electrode by screen printing,
The method for manufacturing a chip-type surge absorber according to claim 5 or 6, wherein the discharge electrode forming step forms the discharge electrode by a sputtering method. The connection electrode forming step forms the connection electrode by screen printing,
The method for manufacturing a chip-type surge absorber according to claim 5 or 6, wherein the discharge electrode forming step forms the discharge electrode by a chemical vapor deposition method.

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