WO1997023025A1

WO1997023025A1 - Surge absorber

Info

Publication number: WO1997023025A1
Application number: PCT/JP1995/002589
Authority: WO
Inventors: Koichi Kurasawa; Sakae Koyata; Takeshi Soe; Nobuya Saruwatari
Original assignee: Mitsubishi Materials Corporation
Priority date: 1995-12-18
Filing date: 1995-12-18
Publication date: 1997-06-26
Also published as: TW281820B

Abstract

A surge absorber provided in input/output circuits or in any other portion of communication equipment where surge voltage may occur, in order to protect electronic devices from trouble or erroneous operation due to lighting surge or interference in the AC power source line. The device has a structure in which a metal wire, arranged in a line and fusible by a current flowing through the line, is connected to a semiconductor surge-absorbing element arranged between the lines.

Description

Description Surge absorber Technical field

The present invention is intended to prevent failure and malfunction of electronic devices due to induced lightning surge, AC power line contact, etc., provided in line input / output circuits of communication devices or other convenient places where surge voltage may occur. Regarding avoidance surge absorber. Background art

Japanese Unexamined Patent Application Publication No. Hei 3-232048 discloses an overvoltage / overcurrent protection function comprising a gap-type or micro-gap-type surge absorbing element and a low-melting metal wire provided in contact with the same. A surge absorber is disclosed. Hereinafter, “gap-type or micro-gap-type surge absorbing element” will be collectively referred to as “discharge tube type surge absorbing element”.

FIG. 7 is an exploded perspective view of a conventional surge absorbing device for overvoltage and overcurrent protection.

Both terminals of a discharge tube type surge absorbing element (micro-gap type surge absorbing element in this example) 16 are connected to lead bins 11 and 13 respectively, and a low melting point metal is applied so as to surround the surge absorbing element 16. A wire (here, a zinc wire) 17 is arranged, and both ends of the low-melting metal wire 17 are connected to lead pins 12 and 14, and a cover 18 is entirely covered.

The operating principle of the conventional example based on the combination of the discharge tube type surge absorbing element 16 and the low melting point gold wire 17 shown in Fig. 7 will be described. When it is used, Thus, the low-melting metal wire 17 provided so as to be thermally coupled is blown to cut off the overvoltage and overcurrent.

However, when the applied current value is relatively small, the heat generated by the discharge is so small that a sufficient amount of heat cannot be obtained to melt the low-melting metal wire 17 in a short time, so that the interruption time may be long. is there. As a result, the discharge type heat absorbing element 16 may be melted or ignited, or the outer resin case may be thermally deformed or ignited, due to the heat generated by the discharge. In addition, there is a risk of adversely affecting other components mounted on the surroundings and the mounting board, and there is a problem in safety.

In addition, since the dimensions of the discharge type surge absorbing element 16 are substantially proportional to the surge current withstand capability, there is a limit to downsizing of the shape in order to secure a practically sufficient surge current withstand capability. For this reason, the shape of the discharge tube type surge absorbing element 16 is restricted, and it is difficult to reduce the size of a conventional surge absorbing element having an overvoltage / overcurrent protection function to a level that allows surface mounting. Disclosure of the invention

In view of the above circumstances, an object of the present invention is to provide a surge absorbing 1R device in which the risk of overheating and ignition due to spontaneous heat generation is prevented.

In order to achieve the above object, a surge absorbing device of the present invention is provided in a line, a hot-melting metal wire which is blown by a current flowing through the line, and a semiconductor-type surge absorbing element arranged between the lines. Are connected.

Here, in the surge absorber of the present invention, a thyristor having a PNPNP junction structure or an NPNNP junction structure can be used as the semiconductor surge absorber.

Further, in the surge absorbing device of the present invention, the hot-melt wire may be: .

97/23025

(3) It is preferable to have a characteristic of fusing within 0.035 seconds with an alternating current of 600 V and 4 O A in effective value. As the above-mentioned heat-fused metal wire, for example, a wire mainly made of aluminum or phosphor bronze having a diameter of 0.5 mm or less can be used.

The problem in the conventional example described above can be solved by using a semiconductor type surge absorbing element as the surge absorbing element and combining it with a heat-fused metal wire to form a small package. .

Here, the semiconductor-type surge absorbing element used in the present invention will be briefly described. A semiconductor-type surge absorbing element, particularly a two-terminal thyristor element having a PNPNP (or NPNPN) junction structure has a breakdown voltage (V bo) or more. When an overvoltage (generally called a surge) is applied to the electrode, the thyristor operates (ignites), and the terminal voltage (generally called the on-state voltage) at this time is suppressed to about 3 to 5 volts. By utilizing this characteristic and connecting and using it in parallel with the circuit to be protected, it is possible to suppress and protect the application of overvoltage to the circuit to be protected.

Generally, the heat generated by the surge absorbing element is proportional to the product of the terminal voltage at the time of absorbing the surge and the surge current flowing at that time. Therefore, when the same surge current flows, the lower the terminal voltage of the surge absorbing element, the lower the heat generation of the element.

In the case of a discharge tube type surge absorbing element, the terminal voltage (arc voltage) during discharge is generally about 30 to 50 volts. On the other hand, in the case of a semiconductor-type surge absorbing element, the on-voltage at the time of surge absorption is about 3 to 5 volts. Therefore, when comparing the calorific value when the same surge current flows, the semiconductor type surge absorbing element can be suppressed to about one tenth of that of the discharge tube type surge absorbing element. It is necessary to satisfy the following two points regarding the fusing characteristics of hot-melt gold wire. The first item is the fusing characteristics when a relatively large overcurrent is applied, which far exceeds the current withstand capability of the semiconductor surge absorber used in combination (mainly the current withstand current with respect to AC current). Instantaneous fusing when a large current is applied is required for safety. There are also safety standards that specify this required characteristic. For example, in the United States UL 497A standard (Secondary protectors for communication circuits), when applying AC 600 volts to 140 amps (effective value), It is required to blow and cut off the current before the fuse specified by the test circuit (Bussman, model name: MDQ-1.6A). Here, the Bussman fuse blows in about 0.035 seconds when this overvoltage overcurrent is applied, so the hot-melting wire used in the present invention must have the property of fusing within a shorter time. Is done. First, the material and diameter of the heat-fused metal wire may be appropriately selected so as to satisfy the requirements of the breaking characteristics for a large current.

The second item is that if an overcurrent with a current value smaller than the current withstand capability of the semiconductor surge absorbing element used in combination (mainly the current withstand capability to withstand alternating current) is applied to the semiconductor The type surge absorber operates normally without deteriorating the characteristics and without excessive heat generation, and it is possible to suppress overvoltage overcurrent. No need to do. Therefore, if a hot-melt wire with a current resistance equal to or greater than that of the semiconductor surge absorbing element is selected, the surge absorption of the overvoltage overcurrent protection function that can be used repeatedly for the application of a relatively small current overcurrent can be achieved. The device becomes feasible.

When an overvoltage overcurrent that is equal to or higher than the breakover voltage of the semiconductor-type surge absorbing element is applied, the semiconductor-type surge absorbing element operates and the applied overvoltage is suppressed to the on-voltage (several volts). At the same time, a surge current flows through the thermal fusion wire. If the current value at this time is larger than the current capacity of the hot-melt metal wire, the hot-melt gold wire will melt and prevent intrusion of overcurrent into the subsequent circuit.

Conversely, if the overcurrent at this time is smaller than the current withstand capability of the hot-melt metal wire, the hot-melt gold wire does not blow, and only the semiconductor-type surge absorbing element operates to suppress the overvoltage. Protect the protected circuit from overvoltage and overcurrent. The overcurrent at this time flows into the semiconductor surge absorbing element in the operating state and the low impedance state, and therefore does not flow into the protected circuit.

By appropriately selecting the current withstand capability of the semiconductor surge absorbing element and the heat-fused metal wire, it becomes possible to comply with various safety standards of each category.

The heat generated by the semiconductor surge absorbing element when absorbing overvoltage and overcurrent is about 1/10 of that of the discharge tube surge absorbing element.There is no risk of abnormal overheating or fire of the element itself, There is no danger of adversely affecting other mounted components or boards.

In addition, the use of a small semiconductor-type surge absorbing element makes it possible to reduce the overall shape, so that the mounting area can be reduced and the surface can be formed into a shape that can be surface-mounted.

Combining the semiconductor-type surge absorbing element described above with a hot-melt wire solves the problem of overheating and ignition due to self-heating, and also allows other parts and components mounted around It is possible to provide a small surge absorbing element for overvoltage / overcurrent protection that does not thermally affect the mounting board.

Further, according to the present invention, it is possible to satisfy various safety standards for overvoltage and overcurrent of communication lines, for example, UL standards in the United States and CSA standards in Canada. BRIEF DESCRIPTION OF THE FIGURES FIG. 1 is a configuration diagram of a first embodiment of a surge absorbing device of the present invention. FIG. 2 is a circuit diagram showing a state where the surge absorbing device of the first embodiment shown in FIG. 1 is connected to a communication line.

FIG. 3 is a configuration diagram of a second embodiment of the surge absorbing device of the present invention. FIG. 4 is a circuit diagram showing a state where the surge absorbing device of the second embodiment shown in FIG. 3 is connected to a communication line.

FIG. 5 is a configuration diagram of a third embodiment of the surge absorbing device of the present invention. FIG. 6 is a circuit diagram showing a state where the surge absorbing device of the third embodiment shown in FIG. 5 is connected to a communication line.

FIG. 7 is an exploded perspective view of a conventional surge absorbing device for overvoltage and overcurrent protection. BEST MODE FOR CARRYING OUT THE INVENTION

Hereinafter, embodiments of the present invention will be described. However, the present invention is not limited by the following description of the embodiments.

(First Embodiment)

FIG. 1 is a configuration diagram of a first embodiment of a surge absorbing device of the present invention. In the present embodiment, a semiconductor surge absorbing element 1 having a breakover voltage (V bo) of about 300 V is used. Further, as the hot-melt wire 2, a phosphor bronze wire is used. A semiconductor surge absorbing element 1 (external 3 mm square, thickness 1 mm) is joined to the lead frame 3 by soldering (not shown), and a thermal bronze wire made of phosphor bronze with a diameter of 0.17 mm 2 This is soldered with a solder 4, wired from the semiconductor type surge absorbing element 1 using the connection conductor 5, and sealed with a resin 6.

FIG. 2 is a circuit diagram showing a state where the surge absorbing device of the first embodiment shown in FIG. 1 is connected to a communication line. In FIG. 2, terminals _a and b and c correspond to the terminals a, b and c in FIG.

The heat-fused metal wire 2 is disposed in one of the two lines 21 and 22 connected to the protected circuit 7, and the current flowing through the line 21 is Blows more. The semiconductor type surge absorbing element 1 is disposed between two lines 21 and 22.

Table 1 shows that the conventional example shown in Fig. 7 and the first embodiment shown in Figs. 1 and 2 show AC 600 V—40 A, 2.2 A, 1 A (all The results of a test that applies three types of overvoltage and overcurrent (effective values) are shown. In the case of the conventional example, the overvoltage overcurrent is applied by connecting the microgap type surge absorbing element and the low melting point gold wire in series, and in the case of the first embodiment, the overvoltage is applied between the terminals a and c in FIG. Overcurrent was applied.

In the first embodiment, a result was obtained that satisfies the required characteristics of both surfaces, that is, the cutoff characteristics when a large current is applied and the protection function when a relatively small current is applied. That is, in the first embodiment, when AC 600 V—40 A is applied, the thermal fusing metal wire is blown off in 0.3 seconds, thereby cutting off the overvoltage and overcurrent. No abnormal heat or ignition was observed at this time. When A C 600 V-2.2 A and 1 A were applied, the thermal fusing wire did not blow, and the semiconductor surge absorbing element operated normally. During the application of the overvoltage and overcurrent, there was no abnormal heating of the semiconductor surge absorbing element, and it was confirmed that there was no problem in terms of safety. In addition, there was no characteristic deterioration after application. That is, it was confirmed that the repetitive operation was possible under these overvoltage overcurrent application conditions.

On the other hand, in the conventional example, the result when AC 600 V—40 A was applied was the same characteristic as that of the first embodiment. However, it was found that under the application condition of AC 600 V—2.2 A, although the low melting point metal wire was blown and the desired operation was performed, only one-time operation could be used. In addition, under the conditions of AC 600 V-1 A, the discharge tube type An adverse effect due to heat generation of the di-absorbing element was observed. It was also found that only one-time operation can be used under this condition.

Regarding the external shape, the first embodiment can be significantly reduced in size, and compared with the mounting area, only one third or less of the conventional example, which is superior to high-density mounting on a board . In addition, it is possible to configure a small package that can be surface-mounted, and it is possible to save labor in the mounting process.

From the above, it was found that the first embodiment is superior to the conventional example.

Table 1 Conventional example Example 1 of the present invention 1 Surge absorbing element Discharge tube Operating voltage 300 V ^ body 動作, operation ¾Ε = 300ν Gold S wire Zinc wire Phosphor bronze wire

AC 600 V—4 OA applied 0.03 sec. To melt zinc wire 〇. 03 sec. To phosphor bronze wire; result after cutting ¾Fire is seen '. Ignition is seen.

d cannot be used again.

AC 600 V-2.2 Λ Fusing zinc wire after 2 to 6 seconds.

Result after 30 minutes of application Ignition: ± seen. During heating, the semiconductor S surge absorber Surge absorber heats up, and the markings operate normally. The characteristics deteriorate after application of excess heat. Suppressed to 300 V or less.

Cannot be used again after £ Π. There is almost no departure.

The surge absorbing element is different from the initial stage where it deteriorates.

Can be used again even after the printing force is 0 ^.

A C 600 V-1 ¾ Lead melts after 50 seconds. Fuse the phosphor bronze wire.

Results after 30 minutes of application (Before fusing: this, during absorption of surge) ^ I-shaped yarn absorption ^ The glass tube of the element ripens, so the element force ^: positive ^ and the excess ^ E ^ Ri i mouth J ^ f f¾ month crack Kaha Ia J ϋ 0 or more?

Yohi 'pace has melted. There is almost no surge absorption and heat generation.

The characteristics of the surge absorbing element are poor because of the characteristics of the surge absorbing element.

Cannot be used again after application. After application, if can be used again. Dimensions (height and height). 1 8 9 1 L mm 1 0 5 1 1 mm

', Case outline) (1st outline) Board mounting area 13 9 = 162 Subrange: 10 5 = 50 mm ² (Second embodiment)

FIG. 3 shows a configuration diagram of the second embodiment. Elements that are the same as the elements of the first embodiment are indicated by the numbers assigned to FIGS. 1 and 2 with the addition of a and b. This is a configuration in which two sets of constituent circuits using semiconductor surge absorbing elements 1a and 1b having the same specifications as those of the first embodiment and heat-fused gold wires 2a and 2b are configured in one package.

FIG. 4 shows an example of a surge protection circuit in which the surge absorber of the second embodiment is connected to a communication line. The terminals _{a to} h in the figure correspond to the terminals _{a to} h shown in FIG. 3, respectively.

Although not shown here, the fusing characteristics with respect to the application of overvoltage and overcurrent are confirmed to be equivalent to those of the first embodiment.

(Third embodiment)

FIG. 5 shows a configuration diagram of the third embodiment. The semiconductor type surge absorbing element 1 in which three semiconductor type surge absorbing elements having the same operating voltage as the first embodiment are formed in one semiconductor chip, and the heat-fused gold wires 2a and 2b, It is configured into individual packages.

FIG. 6 is an example of a surge protection circuit in which the surge absorber of the third embodiment is connected to a communication line. The terminals a to h in the figure correspond to the terminals a to h shown in FIG. 5, respectively.

Claims

The scope of the claims

1. A surge absorber characterized in that a hot-melt metal wire that is arranged in a line and melts by an electric current flowing through the line and a semiconductor-type surge absorbing element that is arranged between the lines are connected. apparatus.

2. The surge absorber according to claim 1, wherein the semiconductor surge absorbing element is a thyristor having a PNPNP junction structure or an NPNNP junction structure.

3. The surge according to claim 1, wherein the heat fusing metal wire has a characteristic of fusing within 0.035 seconds with an effective value of 600 V and 40 A alternating current. Absorber.

4. The surge absorber according to claim 1, wherein the hot-melt wire is mainly made of aluminum or phosphor bronze having a diameter of 0.5 mm or less.