JPH06302257A - Board type temperature fuse - Google Patents

Abstract

PURPOSE:To provide a board type temperature fuse which can have the insulating distance from electrodes to the lateral ends of an insulating board sufficiently, while maintaining the small size of the temperature fuse. CONSTITUTION:On one side surface of an insulating board 1, layer electrodes 2 are provided placing an interval in the width direction, a low melting point fusible alloy wire 4 is bridged between the tips of the electrodes 2, lead wires 3 are connected to the electrodes 2 from the rear end sides of the electrodes, and an insulating layer 6 is provided to cover the whole surface of one side surface of the above insulating board 1. The rear ends 21 of the electrodes 2 are positioned placing an interval (a) from the rear end 11 of the insulating board 1, the interval between the layer electrodes 2 and 2 is made 0.9mm to 1.5mm, and an insulating covered wire is used as the above lead wires 3.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an alloy type substrate temperature fuse which uses a low melting point fusible alloy wire for a fuse element.

[0002]

2. Description of the Related Art There is a temperature fuse as an electric component for protecting an electric device from an overcurrent and preventing a thermal damage of the electric device and a fire from occurring. As this temperature fuse, an alloy type temperature fuse in which a low melting point fusible alloy wire is used for a fuse element is widely used. The basic structure of this alloy type temperature fuse is that a low melting point fusible alloy piece is bridged between lead wires, and a flux is applied to the low melting point fusible alloy piece. Is surrounded by an insulator, and is used by being attached to a protected device where heat is likely to be generated due to an overcurrent, and its operation process is as follows.

That is, when the equipment to be protected generates heat due to an overcurrent, the generated heat melts the low melting point alloy piece, and the molten metal pushes away the already melted flux due to surface tension to form a spherical shape. Progressing, the power supply to the equipment is cut off.

The applicant of the present invention has developed a substrate type temperature fuse as an alloy type temperature fuse. The basic structure of this substrate-type temperature fuse is that layered electrodes are provided on one surface of an insulating substrate at intervals in the width direction, and low melting point fusible alloy wires are bridged between the tips of these electrodes. A lead wire is connected to the electrode from the rear end side of the electrode, and the entire surface of one surface of the insulating substrate is covered with an insulating layer. The insulating substrate surface is used in contact with a protected device.

In this substrate type temperature fuse, the ratio of the insulating substrate surface to the entire surface of the temperature fuse is high,
Compared to other types of temperature fuses, the contact area with the device can be made wider, and since the insulating substrate, such as the ceramic plate, has good thermal conductivity, the heat generated from the protected device can be detected with high sensitivity. Can receive heat.

FIG. 3 is an explanatory view of a substrate type temperature fuse which was initially developed by the present applicant, and 1'is an insulating substrate and 2 ',
2'is a layered electrode provided on one side of the insulating substrate, 3 ',
3'is a lead wire connected to the electrode from the rear end side, 4'is a low melting point fusible alloy wire bridged between the tips of both electrodes 2'and 2 ', 5'is a low melting point fusible The flux applied to the alloy wire,
6'indicates an insulating coating layer provided on the entire surface of one surface of the insulating substrate.

In the substrate type temperature fuse shown in FIG. 3, a circuit that acts on both electrodes 2'and 2'when the molten low melting point fusible alloy is divided during operation of the temperature fuse. The distance d'between the two electrodes 2 ', 2'can withstand the circuit voltage so that the voltage does not cause discharge conduction along the contact interface with air between the rear ends 21', 21 'of both electrodes. The insulation distance is set. In addition, the melted low melting point alloy is insulated from the electrode tip 22 'so that it does not peel off the adhesive interface between the insulating substrate and the insulating coating layer under the expansion pressure of the flux and squeeze out from the edge of the insulating coating layer. The substrate tip 12 'is separated by a predetermined distance b, and the electrode tip 22' and the insulating substrate lateral edge 13 'are separated by a predetermined distance c. Thus, the width L of this substrate type temperature fuse is L = (d '+ 2c + 2f), where f is the width of the layered electrode. However,
This width L is considerably wide, and it is difficult to miniaturize the substrate type temperature fuse.

FIG. 4 shows a substrate-type temperature fuse proposed by the applicant thereafter, and is an improvement of the substrate-type temperature fuse of FIG. 3 for miniaturization. In the substrate type temperature fuse shown in FIG. 4, the distance between the rear ends 21 'and 21' of both electrodes is set to d'as described above.
The interval between 2'and 22 'is set to the interval d required to cut off the electric current by spheroidizing the melted low melting point soluble alloy. The distance between the electrode tip 22 'and the insulating substrate tip 12' is set to b as in the above, and the electrode tip 22 'is set.
The distance between the insulating substrate and the lateral edge 13 'of the insulating substrate is set to c as in the above, and the width of the electrode is set to f as in the above. Therefore, the width L of the substrate type temperature fuse is L = (d + 2c + 2
f).

[0009] Therefore, the interval required to cut off the energization due to the spheroidization of the molten low melting point soluble alloy (even if it is physically divided, the circuit voltage that acts between the divisions at that moment is also And arc occurs, and when the dividing distance reaches a predetermined distance due to the progress of spheroidization and the arc disappears, the electricity is substantially cut off) d is a liquid flux between them. Since it is filled, it is shorter than the above-mentioned distance d'which is necessary to prevent discharge conduction between the rear ends of both electrodes along the contact interface with air under the same circuit voltage. Therefore, FIG.
The width dimension of the substrate type temperature fuse shown in FIG. 3 can be made smaller than that of the substrate type temperature fuse shown in FIG.

[0010]

SUMMARY OF THE INVENTION Depending on how the above-mentioned board type temperature fuse is attached to a protected device,
Since each lateral end of the insulating substrate is at the ground potential and the ground voltage of the circuit voltage acts between each electrode and each lateral end of the insulating substrate,
It is safe to set the distance from each electrode to each end of the insulating substrate so as to withstand this ground voltage.

In the substrate type temperature fuse shown in FIG. 4, however, the minimum distance c'between the lateral edge 13 'of the substrate and the electrode 2'is extremely narrow, and the above ground voltage can be endured. Not get
If the distance is wide enough to withstand the voltage to ground, the width dimension is almost the same as that of the substrate type temperature fuse shown in FIG. 3, and miniaturization cannot be guaranteed.

An object of the present invention is to provide layered electrodes on one surface of an insulating substrate at intervals in the width direction, bridge low melting point fusible alloy wires between the tips of these electrodes, and attach each electrode to the rear electrode. In a temperature fuse in which a lead wire is connected from the end side and an insulating layer is coated on the entire surface of one side of the insulating substrate, while maintaining miniaturization of the temperature fuse, each lateral end of the insulating substrate from each electrode is maintained. Substrate type temperature fuse that can take a sufficiently long insulation distance to
Is to provide

[0013]

In the substrate type temperature fuse of the present invention, layered electrodes are provided on one surface of an insulating substrate at intervals in the width direction, and a low melting point fusible alloy is provided between the tips of these electrodes. Bridge the wires, connect the lead wires from the electrode rear end side to each electrode,
A temperature fuse in which the entire surface of one side of the insulating substrate is covered with an insulating layer.
, The rear end of each electrode is spaced apart from the rear end of the insulating substrate, and the distance between the layered electrodes is 0.9 mm to 1.5 m.
m, and an insulating coated wire is used for the lead wire.

[0014]

The linear path from the rear end of one electrode to the rear end of the other electrode is constituted by the adhesive interface between the insulating substrate and the insulating coating layer, and the insulating property of this interface is melted during the operation of the temperature fuse. Since it has a higher insulation than the insulation of the molten flux space between the low melting point fusible alloys, the electrode spacing over the entire length of the electrode is the minimum distance required for current interruption due to fusing of the low melting point fusible alloy wire ( If it is set to 0.9 mm to 1.5 mm), it is possible to avoid discharge conduction between the rear ends of both electrodes when the energization is cut off by cutting the low melting point fusible alloy. Therefore, the electrode interval can be set to 0.9 mm to 1.5 mm over the entire length of the electrode to make the interval narrower than in the conventional case, and the insulation distance between each electrode and each lateral end of the insulating substrate can be increased accordingly.

[0015]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is an explanatory plan view showing an embodiment of the present invention. In FIG. 1, reference numeral 1 is an insulating substrate having good thermal conductivity, and a ceramic plate is usually used. Reference numerals 2 and 2 are layered electrodes provided on one surface of the insulating substrate 1 at intervals in the width direction, and are formed by baking a conductive paint such as silver paste or etching the copper foil of the copper foil laminated insulating substrate. I am doing it.
The rear end 21 of each electrode 2 is located at a predetermined distance a from the rear end 11 of the insulating substrate. b is the distance between the electrode tip 22 and the insulating substrate tip 12, and c is the electrode 2 and the insulating substrate lateral edge 1.
3 and 3 are shown respectively.

Reference numeral 3 denotes an insulating coated lead wire, which is a single wire conductor 3
1 is extrusion-coated with a plastic insulating layer, and the end 32 of the coating layer is substantially aligned with the rear end 21 of the electrode.
3 is connected to the electrode 2 by soldering, welding or the like.

Reference numeral 4 denotes a low melting point fusible alloy wire bridged by welding or the like between the tips of the electrodes 2 and 2. 5 is a flux applied on the low melting point fusible alloy wire 4. An insulating coating layer 6 is provided on the entire surface of one surface of the insulating substrate, and can be provided by, for example, dropping coating of an epoxy resin liquid.

The above-mentioned substrate type temperature fuse is used by being attached to the protected equipment as described above. When the low melting point fusible alloy wire is melted by the heat generated by the overcurrent of the protected equipment, the molten metal pushes away the molten flux due to the surface tension and spheroidizes and divides. When the distance is reached, the energization between the electrodes is cut off and the circuit voltage acts between the electrodes.

Now, assuming that the molten metal is completely mounted on the tip portion of the electrode and the current is cut off by dividing the electrode, [this is a normal dividing mode because the electrode is easily wet with the molten metal (molten solder). ] The route between the divisions is in a state of being filled with the molten flux, and since the molten flux has a low insulating property in which the oxide of the low melting point soluble alloy wire is dissolved, The insulation strength is lower than the insulation strength per unit distance at the adhesive interface between the insulating substrate and the insulating coating layer.

Therefore, if the distance d between the electrodes 2 and 2 is set to a distance required for current interruption due to melting of the low melting point fusible alloy wire, after arc interruption due to cutting of the molten low melting point fusible alloy. It is possible to eliminate the conduction of re-discharge at the same location and the conduction of discharge between the lower ends 21 and 21 of both electrodes, which is the adhesive interface between the insulating substrate and the insulating coating layer between the electrodes, and to reliably cut off the energization. The interval required for interrupting the current by melting the low melting point fusible alloy wire is 0.9 mm to 1.5 mm under a rated voltage of 250 V, and the electrode interval d is set to 0.9 mm to 1.5 mm. .

In the substrate type temperature fuse, when both lateral ends are exposed to the ground potential due to mounting and fixing, a circuit voltage to ground acts between the electrode 2 and the insulating substrate lateral end 13. ,
This voltage value is 1 / √3 times the interphase voltage, and the distance required for insulation of this ground voltage is 1 / √3 times the electrode interval. Therefore, in the above-mentioned substrate type temperature fuse, the distance c between the lateral edge 13 of the insulating substrate and the electrode 2 is such that the molten low melting point fusible alloy peels off the adhesive interface between the insulating substrate and the insulating coating layer. It is set to a predetermined distance so that it will not be pressed out to the outside, and the distance is usually 1.20 mm. Therefore, this distance is the distance required to insulate the earth voltage ((0.9 mm to 1.5 mm)
1 / √3 times of the above], there is no problem in insulation even if both lateral ends of the substrate type temperature fuse are held at the ground potential.

In the substrate type temperature fuse of the present invention,
An insulated coating wire is used for the lead wire 3, and the rear end 21 of the electrode is positioned inside the rear end 11 of the insulating substrate, so that
The exposure of the conductor 31 and the rear end 21 of the electrode is eliminated, the electric stress is prevented from acting on the contact surface with air, and the insulation strength between the rear ends 21 and 21 of both electrodes is increased. Even if the interval is set to the interval required for current interruption due to the melting of the low melting point fusible alloy wire, re-discharging conduction and It is possible to eliminate the discharge continuity between the lower ends of the electrodes and reliably cut off the energization, which is also clear from the following test results.

Test results a = 0.5 mm, b = 1.4 mm, c = 1.2 mm, d =
1.1 mm, electrode width = 1.4 mm, and the thickness of the insulating substrate is 0.
A ceramic plate of 6 mm is used, a layered electrode is provided by baking a silver paste, an insulating coating lead wire having a conductor diameter of 0.51 mm is used, and a low melting point fusible alloy wire is 0.3 mm thick. Use a 0.4 mm wide rectangular cross section with a melting point of 98 ° C, and use an epoxy resin layer with a thickness of 1.8 mm as the insulating coating layer, and use a substrate temperature fuse of rated voltage 250 V for 50
Individually manufactured, the temperature is 120 ° C with the rated voltage of 250V applied.
When it was soaked in the oil of No. 3 and operated to be disassembled, no trace of discharge was observed except at the cut portion of the low melting point fusible alloy wire.

FIG. 2 shows a substrate-type temperature fuse of another embodiment of the present invention, in which the width e of the electrode tip 2a bridging the low melting point fusible alloy wire piece 4 is set to the lead wire lead conductor 33. Is narrower than the width f of the electrode body 2b connecting the electrodes, and the gap between the electrode tip 2a and the lateral edge 13 of the insulating substrate is melted. The distance between the electrode body 2b and the lateral end 13 of the insulating substrate is set to the ground potential at both lateral ends of the substrate type temperature fuse. The gap g is set so as to insulate the ground voltage when it is held, and the other structure is the same as that of the embodiment shown in FIG. In the embodiment shown in FIG.
The width can be narrowed by 2 (fe) as compared with the embodiment shown in FIG.

[0025]

The substrate-type temperature fuse of the present invention has the above-described structure, and the layered electrodes are provided on one surface of the insulating substrate at intervals in the width direction and have a low melting point between the tips of these electrodes. In a temperature fuse in which a fusible alloy wire is bridged, a lead wire is connected to each electrode from the rear end side of the electrode, and an insulating layer is coated on the entire surface of one side of the above-mentioned insulating substrate, the energization of the temperature fuse is cut off. The distance between both electrodes can be made smaller than the conventional example without affecting the performance, and as a result, the distance between the electrode and the lateral edge of the insulating substrate can be widened and the insulation distance between them can be lengthened. Even if it is used while it is kept at the ground potential, sufficient insulation from the ground can be guaranteed.

[Brief description of drawings]

FIG. 1 is an explanatory diagram showing an embodiment of the present invention.

FIG. 2 is an explanatory diagram showing another embodiment of the present invention.

FIG. 3 is an explanatory diagram showing a conventional example.

FIG. 4 is an explanatory diagram showing another conventional example different from the above.

[Explanation of symbols]

 1 Insulating substrate 2 Layered electrode 3 Insulation coated wire 4 Low melting point fusible alloy wire d Space between layered electrodes

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[Procedure amendment]

[Submission date] June 4, 1993

[Procedure Amendment 1]

[Document name to be amended] Statement

[Correction target item name] 0014

[Correction method] Change

[Correction content]

[0014]

The linear path from the rear end of one electrode to the rear end of the other electrode is composed of the adhesive interface between the insulating substrate and the insulating coating layer, and the insulating property of this interface is the low melting point when the thermal fuse is activated. Since the insulation is higher than the insulation of the molten flux space between the sections of the melting point fusible alloy, an electrode interval is required over the entire length of the electrode to cut off the current by melting the low melting point fusible alloy wire.
By setting the interval (0.9mm~1.5mm) such, upon energization block by dividing the low-melting fusible alloy, it is possible to avoid the discharge conduction between the electrodes rear. Therefore, the electrode interval can be set to 0.9 mm to 1.5 mm over the entire length of the electrode to make the interval narrower than in the conventional case, and the insulation distance between each electrode and each lateral end of the insulating substrate can be increased accordingly.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Ritsu Nishide 1-1-11 Shimanouchi, Chuo-ku, Osaka Uchihashi STEC Co., Ltd.

Claims (2)

[Claims] 1. A layered electrode is provided on one surface of an insulating substrate at intervals in the width direction, a low melting point fusible alloy wire is bridged between the tips of these electrodes, and each electrode is relieved from the rear end side of the electrode. -In a temperature fuse in which a wire is connected and the entire surface of one surface of the insulating substrate is covered with an insulating layer, the rear end of each electrode is located at a distance from the rear end of the insulating substrate to melt the gap between the layered electrodes. A substrate-type temperature fuse characterized in that an insulating coating wire is used for the lead wire, which is set at an interval required to cut off the electric current by spheroidizing the low melting point soluble alloy. 2. The substrate type temperature fuse according to claim 1, wherein the distance between the layered electrodes is 0.9 mm to 1.5 mm.