JPH08236260A - Chip-type absorber and manufacture thereof - Google Patents

Abstract

PURPOSE: To excellently absorb instantaneous surge voltage and adjust discharge starting voltage and response voltage to be desired values by installing a pair of opposed electrodes having a micro gap in the conjunction interface of a joined chip body and forming a recessed part to be filled with an inert gas in the chip body. CONSTITUTION: A chip-type surge absorber 10 is made of a joined chip body 13 composed of insulated first and second chip bodies 11, 12 and having electrodes 16, 17 which are on the opposite each other, form a gap 14 between them, and are connected with terminal electrodes 18, 19. In the chip body 12, a recessed part 12a facing to the gap 14 is formed and an inert gas is sealed in the recessed part 12a. With this structure, surge absorbers can be miniaturized and manufactured at high productivity and moreover the absorbers can excellently absorb instantaneous surge voltage e.g. lightening surge, of which discharge starting voltage and response voltage can be controlled to be desiring values by easily adjusting the length of the gap 14.

Description

Detailed Description of the Invention

[0001]

The present invention relates to a telephone, a facsimile,
The present invention relates to a chip type surge absorber that can be surface-mounted on a printed circuit board and absorbs a surge voltage applied to an electronic device for a communication device such as a telephone exchange and a modem. More specifically, the present invention relates to a chip type surge absorber in which a pair of counter electrodes having a micro gap are hermetically sealed together with an inert gas.

[0002]

2. Description of the Related Art Conventionally, as hermetically sealed microgap type surge absorbers, surge absorbers 9a and 9b as shown in FIGS. 8 and 9 have been known. The gap type surge absorbing element 1 built in the two surge absorbers 9a and 9b has a width of 10 μm which divides the coating film 1a into two in the center of the cylindrical ceramic body 1b covered with the conductive coating film 1a. The microgap 1
c is formed, and a pair of cap electrodes 1d and 1e are attached to both ends of the ceramic body 1b. Electrical insulation is achieved between the films divided into two by the microgap 1c. As shown in FIG. 8, the surge absorber 9a accommodates the surge absorbing element 1 in a tube 4 having an insulating property, arranges a pair of sealing electrodes 2 and 3 at both ends of the surge absorbing element 1, and seals them. The stop electrodes 2 and 3 are electrically connected to the cap electrodes 1d and 1e, and at the same time, an inert gas 5 such as Ar gas is sealed inside the tube 4. Lead wires 6 and 7 are connected to the sealing electrodes 2 and 3, respectively.

As shown in FIG. 9, a surge absorber 9b is provided.
Is made by sealing the gap type surge absorbing element 1 with the glass tubes 8 together with the lead wires 6 and 7 connected to the cap electrodes 1d and 1e at both ends thereof. The glass tube 8 is filled with an inert gas 5 such as Ar gas. In the above surge absorber 9a or 9b, the lead wires 6, 6
When an abnormal voltage is applied to 7, glow discharge first occurs along the conductive film 1a enclosing the cylindrical ceramic body 1b, and finally an arc discharge occurs between the pair of cap electrodes 1d and 1e. And absorb the surge voltage.

The surge absorber 9a or 9b is connected to a pair of input lines of an electronic device in parallel with the electronic device and is configured to operate at a voltage higher than the operating voltage of the electronic device. That is, although the surge absorber is a resistor having a high resistance value at a voltage lower than its discharge starting voltage,
When the applied voltage is equal to or higher than the discharge start voltage, the resistance element has a low resistance value of several tens Ω or less. When a surge voltage such as a lightning surge of several kV to several tens of kV is momentarily applied to the electronic device, the surge absorber is discharged, and the surge voltage is absorbed to protect the electronic device. If you do not install this type of surge absorber in front of the electronic device,
Abnormal voltage (surge) penetrates into electronic devices, causing dielectric breakdown and other malfunctions of electronic devices.

[0005]

However, since the surge absorbers 9a and 9b have a cylindrical shape, it is very difficult to form a chip, and there is a drawback that they cannot be mounted on the surface of a printed circuit board. Further, since the surge absorbing element 1 is sealed with the insulating tube 4 and the glass tube 8, there is a problem that the shape becomes large. Further, since the microgap 1c is formed by cutting the conductive film 1a with a cutter or a laser beam, it is relatively difficult to adjust the discharge start voltage, the response voltage, etc. to desired values, and mass production is difficult. There was a problem.

The object of the present invention is to absorb a momentary surge voltage such as a lightning surge, to easily adjust the microgap, and to adjust the discharge start voltage and the response voltage to desired values. It is to provide a surge absorber. Another object of the present invention is to provide a chip type surge absorber that can be surface-mounted on a printed circuit board, is easy to manufacture, is easy to miniaturize, and is excellent in mass productivity.

[0007]

As shown in FIGS. 1, 2, 5, and 7, a chip type surge absorber 1 of the present invention is provided.
Nos. 0, 20 and 40 are bonded chip bodies 13 in which a first chip body 11 having an insulating property and a second chip body 12 having an insulating property are integrally bonded, and a bonding interface of the bonded chip body 13 has a micro structure. A pair of counter electrodes 16 and 17 formed so as to have a gap 14, and these counter electrodes 16 and 17
A pair of terminal electrodes 18 and 19 which are connected to each other and are provided at both ends of the outer surface of the bonded chip body 13, and the second chip body 1.
The second concave portion 12a is formed at a position facing the micro gap 14 and has an inert gas filled therein. As shown in FIG. 6, in another chip-type surge absorber 30 of the present invention, a recess 11a in which an inert gas is filled is provided.
Are formed on the first chip body 11.

As shown in FIGS. 4 (a) to 4 (h), in the method of manufacturing the chip type surge absorber 10 of the present invention, a plurality of recesses 12a are formed on the surface of the second substrate 22 having an insulating property at intervals t. And forming a plurality of pairs of through holes 21a, 21 in the first substrate 21 at intervals t corresponding to the intervals t of the recesses 12a.
a, a step of filling the through holes 21a, 21a with the conductive material 25, and a step of covering the through holes 21a, 21a on the surface of the first substrate 21 to form a plurality of micro gaps 14 respectively. The step of forming the first electrode pattern 26, and the through holes 21a,
21a, a step of forming a plurality of second electrode patterns 27 at intervals so as to cover the peripheral portion of the hole, and a first substrate 21 on which the electrode patterns 26 and 27 are formed and a second substrate on which the recess 12a is formed. 22 is integrally bonded in an inert gas atmosphere so that the recess 12a and the microgap 14 face each other, and the bonded substrates 21 and 22 are diced for each recess 12a to form the first chip body 11 and the second chip body 2. By manufacturing the bonded tip body 13 composed of the chip body 12, the pair of opposed electrodes 1 is formed at the bonded interface of the bonded tip body 13.
6, 17 and the pair of terminal electrodes 1 respectively connected to the pair of counter electrodes 16 and 17 at both ends of the outer surface of the bonded chip body 13.
8 and 19 are formed.

Although not shown, in the method of manufacturing the chip type surge absorber 20 shown in FIG. 5, a plurality of recesses 12a and a plurality of pairs of through holes 22a, 22a are formed in the second substrate 22,
This is a method of forming a pair of terminal electrodes 18 and 19 on both ends of the outer surface of the second chip body 12 made of the second substrate 22.
Although not shown, the method of manufacturing the chip type surge absorber 30 shown in FIG.
a and a plurality of pairs of through holes 21a, 21a are formed, and a pair of terminal electrodes 18, 19 are formed at both ends of the outer surface of the first chip body 11 made of the first substrate 21.

The present invention will be described in detail below. (a) First Substrate and Second Substrate The first substrate 21 and the second substrate that respectively produce the first chip body 11 and the second chip body 12 of the present invention are substrates having an insulating property. Examples of these substrates include an insulating glass substrate, an insulating ceramic substrate such as alumina and mullite, or a silicon wafer. This silicon wafer has a resistivity of substantially 1000
One having a resistance of 10,000 cmΩ is selected. If this silicon wafer is used, a chip-type surge absorber can be manufactured at low cost by using an existing semiconductor chip manufacturing apparatus. The above-exemplified substrate is used for either or both of the first substrate and the second substrate. It is preferable that one or both of the first substrate and the second substrate are made of a transparent or semi-transparent material because the discharge state of the surge absorber can be observed from the outside of the surge absorber. Examples of this transparent body include a glass substrate, and a ceramic substrate made of a ceramic sintered body that transmits visible light, such as PLZT and transparent alumina.

(B) Recesses and through holes Recesses 11a, 12a and through holes 21a, 22a of the substrate
Is formed by dry etching such as sputtering or laser light after masking the other portions where the recesses and the through holes are to be formed, or leaving the portions where the recesses and the through holes are to be formed. After the others are covered with a resist film, they are formed by wet etching with an etchant that corrodes the substrate. When the substrate is a silicon wafer, the recess and the through hole can be similarly formed by laser drilling, chemical etching, or a combination thereof. A plurality of these recesses and through holes are formed at predetermined intervals on the substrate so that the bonded chip body 13 shown in FIGS. 1 and 5 can be obtained.
That is, when the first substrate and the second substrate are joined together, a pair of through-holes are formed so as to sandwich this recess centering on one recess (FIGS. 4A to 4G).

(C) First electrode pattern and second electrode pattern The first electrode pattern 26 and the second electrode pattern 27 are A
By a thick film forming method of coating a conductive paste containing u, Ag, Ag / Pd, Cu, etc. by screen printing or the like, or by sputtering these metals, a vapor deposition method,
It is formed by a thin film forming method such as an ion plating method, a plating method, or a CVD method. The solder bumps 18b and 19b, which will be described later, can be formed after the electrode pattern is formed. The first electrode pattern serving as the pair of counter electrodes 16 and 17 is not limited to the pattern shown by the broken line in FIG. 2, but various types as shown in FIGS. 3 (a) to 3 (f) can be obtained by the thick film or thin film forming method. An electrode pattern is formed. These electrodes 1
The gap width w (FIG. 3A) of the microgap 14 formed between 6 and 17 is 0.1 μm depending on the shape of the gap and the desired discharge start voltage and the value of the response voltage.
˜1000 μm range. In FIG. 2, the shape of the gap 14, that is, the electrodes 16 and 1 that form the gap.
The shape of each of the opposing ends of 7 is flat. FIG. 3 (a)
3 is a mountain shape, and FIG. 3 (b) is a comb shape.
3 (c) shows three twisted shapes, and FIG. 3 (d) shows FIG.
It is a composite form of (b) and FIG. 3 (c). Further, in the example shown in FIG. 3E, the small circular electrode 16 is connected to the microgap 1
The strip-shaped electrode 17 is provided so as to surround the electrode 4. In this case, although not shown, since the through hole 21a connected to the electrode 16 faces the recess, two or more substrates facing the recess are stacked in order to keep the recess airtight. In the example of FIG. 3 (e), when a surge voltage is applied between the electrodes 16 and 17, the electrodes are discharged evenly around the small circular electrode 16, so that a high voltage is not applied locally and the electrode pattern is destroyed. To be prevented. In the example shown in FIG. 3 (f), the opposing ends between the electrodes 16 and 17 are lengthened by blunting the comb-shaped tips in FIG. 3 (b) to prevent electrode breakdown due to local high voltage.

(D) Bonding of Substrate and Encapsulation of Inert Gas The bonding of the first substrate 21 and the second substrate 22 is performed by positioning the microgap 14 at the center of the recess 11a or 12a. As the bonding method, in the first method, the first electrode pattern is made of an Au conductor, and at the same time, the bonding surfaces of both substrates are metallized for hermetic sealing, and then both substrates are thermocompression bonded at a temperature of about 400 ° C. In the second method, when a glass substrate is used as the substrate, both substrates are superposed and then joined by being thermally softened by a carbon heater. Further, in the third method, both substrates are joined with an epoxy adhesive, solder, brazing material or the like. Since the inert gas is filled in the recesses, the atmosphere at the time of bonding is an inert gas atmosphere. The inert gas filled in the recess is a gas selected from the group consisting of He, Ne, Ar, Kr, Xe, N ₂ and CO ₂ gas, or two or more kinds thereof.

(E) Chip Formation and Formation of Terminal Electrodes Both the bonded substrates are made into chips by dicing with a diamond blade so that the recesses are located at the center and at intervals where the recesses are formed. The obtained bonded tip body 13 forms a rectangular parallelepiped. The pair of terminal electrodes 18 and 19 formed from the second electrode pattern by this chip formation is the electrode layer 1 formed from the second electrode pattern 27 shown in FIG.
Although it may be formed by only 8a and 19a,
As shown in FIGS. 5 and 6, solder bumps 18b and 19b made of Sn or Sn / Pb may be provided on the electrode layers 18a and 19a to form the bumps. As described above, these solder bumps may be formed immediately after forming the second electrode pattern and before dicing.
Further, as shown in FIG. 7, lead wires 18c and 19c are soldered to the electrode layers 18a and 19a instead of the solder bumps to form a pair of terminal electrodes 18 and 19 to obtain a chip type surge absorber 40. You can also

[0015]

Operation: Chip type surge absorber 10-40 of the present invention
When an overvoltage or an overcurrent continuously enters the line to which the pair of terminal electrodes 18 and 19 are connected, a discharge is generated between the micro gaps of the counter electrodes 16 and 17 located in the recess 14. The degree of damage to the counter electrode due to the heat generated by this discharge becomes severe, and the gap distance increases. As a result, before the surge absorbers 10 to 40 can be fatally damaged by heat, their resistance values increase, the discharge start voltage and the discharge sustaining voltage become higher than the overvoltage, and the discharge is stopped.

[0016]

Embodiments of the present invention will now be described in detail with reference to the drawings together with comparative examples. Example 1 A gap type chip type surge absorber 10 shown in FIGS. 1 and 2 was manufactured based on FIG. First, an insulating silicon wafer having a thickness of 0.6 mm 2
2 has a plurality of concave portions 12 at equal intervals of t = 1.57 mm.
a was formed. This interval tmm corresponds to the length of the bonded tip body 13. Specifically, as shown in FIGS. 4A and 4B, a mask 28 in which a window hole 28a is formed in a portion where a concave portion is to be formed on the surface of the silicon wafer 22 is coated on the surface of the wafer 22 and a dry process is performed. Etched. FIG.
In (a), t ₁ is 0.5 mm and t ₂ is 1.07 mm
Is. On the other hand, a plurality of pairs of through holes 21 are formed in the insulating glass substrate 21 having a thickness of 0.2 mm at an interval of t = 1.57 mm.
a was formed. Specifically, as shown in FIGS. 4C and 4D, a laser drill and chemical etching were performed on the portion where the through hole is to be formed, thereby forming a through hole 21a having a diameter of 0.2 mm. In FIG. 4C, 29 is a resist film, 29a is its hole, and t ₃ is 0.61 m.
m and t ₄ are 0.96 mm.

As shown in FIG. 4 (e), a plurality of through holes 2
An Ag polyimide adhesive paste 25, which is a conductive material, was filled and printed on 1a by a thick film technique and cured at 180 ° C. for 30 minutes. Then, on the surface of the glass substrate 21, a width of 10 μm
A plurality of first electrode patterns 26 were formed so as to have the micro gaps 14 of. This was done by forming a conductor film by thin film technology and then patterning by photoetching. As shown in FIG. 4F, the glass substrate 2
1 was turned upside down, and a plurality of second electrode patterns 27 were formed on the back surface of the substrate 21 at intervals so as to cover the hole peripheral portion including the through holes 21a in the same manner as the first electrode pattern.
Then, as shown in FIG.
The glass substrate 21 on which No. 7 was formed and the silicon wafer 22 on which the recess 12a was formed were integrally bonded in an inert gas atmosphere of Ar gas so that the recess 12a and the microgap 14 faced each other. An epoxy adhesive was used for joining. As a result, Ar gas was enclosed in the recess 12. As shown by the broken line in FIG. 4 (g), the bonded glass substrate 21 and silicon wafer 22 were diced for each recess 12a.

As shown in FIGS. 4 (h) and 1, a bonded chip body 13 composed of a first chip body 11 and a second chip body 12 was produced by this dicing. Solder bumps 18b and 19b were respectively formed on the electrode layers 18a and 19a (FIG. 2) formed by the second electrode pattern 27.
As a result, a pair of opposing electrodes 16 and 17 are provided at the joining interface of the joining chip body 13, and a pair of terminal electrodes 18 and 19 including the electrode layers 18a and 19a and solder bumps 18b and 19b are provided at both ends of the outer surface of the first chip body 11. Was formed. The pair of terminal electrodes 18 and 19 were connected to the pair of opposing electrodes 16 and 17, respectively, through a conductive material filled in the through holes. This tip type surge absorber 10 has a length of about 1.42 m.
m, the width was about 1.42 mm, and the height was about 0.8 mm.

<Embodiment 2> A pair of counter electrodes 1 having an electrode pattern having a gap width w of 10 μm shown in FIG.
A chip type surge absorber was produced in the same manner as in Example 1 except that Nos. 6 and 17 were formed.

<Embodiment 3> A pair of counter electrodes 1 having an electrode pattern having a gap width w of 10 μm shown in FIG. 3B.
A chip type surge absorber was produced in the same manner as in Example 1 except that Nos. 6 and 17 were formed.

<Comparative Example 1> The gap type surge absorber 9a shown in FIG. The surge absorber 9a has a width 3 that divides the coating 1a into two in the circumferential direction at the center of a cylindrical ceramic body 1b covered with a conductive coating 1a.
A microgap 1c of 0 μm was formed, and a pair of cap electrodes 1d and 1e were capped on both ends of this ceramic body 1b. The surge absorber 9a accommodates the surge absorbing element 1 in a tube 4 that maintains insulation, arranges a pair of sealing electrodes 2 and 3 at both ends of the surge absorbing element 1, and caps these sealing electrodes 2 and 3. It was made by electrically connecting to the electrodes 1d and 1e and at the same time enclosing Ar gas 5 inside the tube 4 at a pressure of 800 Torr. Lead wires 6 and 7 were connected to the sealing electrodes 2 and 3, respectively.

<Comparative Test and Evaluation> With respect to the surge absorbers of Examples 1 to 3 and Comparative Example 1, the discharge start voltage, the response voltage to the (1.2 × 50) μsec 10 kV surge voltage, the insulation resistance and the capacitance were measured. Then
An overvoltage / overcurrent application test and a surge withstand test were performed. Overvoltage / overcurrent application test is AC600V-3
An overvoltage / overcurrent of 00 mA was applied for 5 minutes. In the surge withstand test, a current value which can withstand a (8 × 20) μsec surge was measured. Table 1 shows the results.

[0023]

[Table 1]

As is clear from Table 1, the chip type surge absorbers of Examples 1 to 3 had the same discharge performance as the conventional surge absorber 9a. In particular, the discharge start voltage and the response voltage could be changed by changing the gap width and the gap shape.

[0025]

As described above, according to the present invention, in addition to absorbing a momentary surge voltage such as a lightning surge, when there is a continuous overvoltage or overcurrent intrusion, The conductive film of the conductive ceramic thin film is thermally damaged and the gap interval is widened to increase the discharge start voltage and the discharge sustaining voltage, which causes not only abnormal heat generation of the surge absorber but also electronic equipment and a printed circuit board on which the equipment is mounted. It is possible to prevent thermal damage, ignition, etc. Further, since the surge absorber of the present invention is not a conventional cylindrical insulating tube, it can be easily made into a chip, can be miniaturized, occupies a small space, is easy to assemble, and is excellent in mass productivity. This allows easy mounting on the surface of the printed circuit board.
Further, compared with the conventional method of forming a microgap with a laser beam or a diamond blade, in the present invention, since it is formed by a thin film or thick film forming technique, not only can the gap forming time be shortened, but the gap width and the gap shape can be changed to a desired discharge. It can be easily optimized depending on the characteristics.

[Brief description of drawings]

FIG. 1A of FIG. 2 of the chip type surge absorber of the present invention
-A line sectional view.

FIG. 2 is a plan view thereof.

FIG. 3 is a plan view of a pair of counter electrodes showing various gap shapes according to the present invention.

FIG. 4 is a cross-sectional view showing a method of manufacturing the chip type surge absorber shown in FIGS. 1 and 2.

5 is a sectional view corresponding to FIG. 1, showing another chip type surge absorber of the present invention.

FIG. 6 is a cross-sectional view corresponding to FIG. 1, showing still another chip type surge absorber of the present invention.

FIG. 7 is a cross-sectional view corresponding to FIG. 1, showing still another chip type surge absorber of the present invention.

FIG. 8 is a central longitudinal cross-sectional view of a gap type surge absorber of a conventional example.

FIG. 9 is a central longitudinal sectional view of another conventional gap type surge absorber.

[Explanation of symbols]

 10, 20, 30, 40 Chip type surge absorber 11 First chip body 11a, 12a Recessed portion 12 Second chip body 13 Bonded chip body 14 Microgap 16,17 Counter electrode 18,19 Terminal electrode 21 Glass substrate (first substrate) 21a, 22a Through hole 22 Silicon wafer (second substrate) 25 Conductive material 26 First electrode pattern 27 Second electrode pattern

Claims (5)

[Claims] 1. A bonded chip body (13) in which an insulative first chip body (11) and an insulative second chip body (12) are integrally bonded, and the bonded chip body (13). ) Micro-gap (1
4) a pair of counter electrodes (16, 17) formed to have
A pair of terminal electrodes (18, 19) respectively connected to the pair of opposing electrodes (16, 17) and provided at both ends of the outer surface of the bonded tip body (13); and the first chip body (11) Alternatively, a chip type surge absorber having a recess (11a or 12a) formed in a position facing the micro gap (14) of the second chip body (12) and having an inert gas filled therein. 2. A first chip body (11) and a second chip body (12)
2. The chip type surge absorber according to claim 1, wherein either one or both of them is a transparent or semi-transparent chip body. 3. A gap is provided on the surface of either one of the insulating first substrate (21) and the insulating second substrate (22).
(t) to form a plurality of recesses (11a or 12a), and the gap between the recesses (11a or 12a) in the other substrate of the first substrate (21) or the second substrate (22) interval (t) corresponding to (t)
A step of forming a plurality of pairs of through holes (21a, 21a or 22a, 22a), the step of filling the through holes (21a, 21a or 22a, 22a) with a conductive material (25), the first substrate (21) or the second substrate (22), the surface of the other substrate is covered with the through-holes (21a, 21a or 22a, 22a) and has a plurality of first gaps (14) each having a microgap (14).
Step of forming an electrode pattern (26), the through hole (21a, 21a or 22a, 22 in the back surface of the other substrate
a) forming a plurality of second electrode patterns (27) at intervals so as to cover the periphery of the hole including a), the recess (12a), the first electrode pattern (26), and the second electrode pattern (26). First substrate (21) and second substrate respectively formed with (27)
(22) the recess (11a or 12a) and the micro gap (1
4) are integrally bonded in an inert gas atmosphere so that they face each other, and the bonded both substrates (21, 22) are diced for each recess (11a or 12a) to form a first chip body (11). ) And the second chip body (12)
By forming a bonded chip body (13) made of the above, a pair of opposed electrodes (16, 17) are provided at the bonded interface of the bonded chip body (13) and the pair of opposed electrodes are provided at both ends of the outer surface of the first chip body (11). A pair of terminal electrodes (18, 19) respectively connected to the counter electrodes (16, 17)
And a method of manufacturing a chip type surge absorber, the method comprising: 4. A step of forming a plurality of recesses at intervals on the surface of either one of the first substrate having an insulating property and the second substrate having an insulating property, and the one so as to sandwich the recesses. Forming a plurality of pairs of through holes on the substrate at intervals, filling the through holes with a conductive material, and forming the recess on the surface of the other substrate of the first substrate or the second substrate. Forming a plurality of first electrode patterns so as to have a microgap at an interval corresponding to the interval, and providing an interval on the back surface of the other substrate so as to cover the hole peripheral part including the through hole. A step of forming a plurality of second electrode patterns, and an inert gas so that the concave portion and the microgap face the first substrate and the second substrate on which the concave portion, the first electrode pattern and the second electrode pattern are formed, respectively. Atmosphere A step of integrally joined at medium, the by dicing the two substrates described above bonded to each of the recesses 1
Bonded chip body consisting of chip body (11) and second chip body (12)
By manufacturing (13), a pair of counter electrodes (16, 17) and the second chip body (12) are formed at the joint interface of the joint tip body (13).
Forming a pair of terminal electrodes (18, 19) respectively connected to the pair of counter electrodes (16, 17) on both ends of the outer surface of the chip type surge absorber. 5. The chip type surge absorber according to claim 3, wherein one or both of the first substrate (21) and the second substrate (22) are transparent or semitransparent substrates.