CN110491609A - Overheat protection device, varistor - Google Patents

Abstract

An overheat protection device and a varistor are provided. The overheat protection device comprises: a first electrode and a second electrode arranged at an interval; a hot-melt wire located between the first electrode and the second electrode, the hot-melt wire being in electrical contact with the first electrode and the second electrode; and an insulator supporting the first electrode and the second electrode, wherein the hot-melt wire melts into a liquid hot-melt material when the ambient temperature reaches a predetermined temperature, the liquid hot-melt material soaks the first electrode and the second electrode, and the liquid hot-melt material does not soak at least a portion of the insulator located between the first electrode and the second electrode.

Description

Overheat protection device, varistor

technical field

The invention relates to the field of circuit protection, in particular to an overheat protection device and a varistor.

Background technique

The varistor is a resistive device with nonlinear volt-ampere characteristics. It is mainly used for voltage clamping when the circuit is under overvoltage, and absorbs excess current to protect sensitive devices. It is connected in parallel in the circuit, which is equivalent to a variable Resistance, when the circuit is in normal use, the impedance of the varistor is very high, the leakage current is very small, it can be regarded as an open circuit, and has almost no effect on the circuit. But when a very high surge voltage comes, the resistance value of the varistor drops instantly (its resistance value can change from megohm level to milliohm level), so that it can flow a large current and at the same time reduce the overvoltage clamped at a certain value.

Thermally protected varistors are products in which alloy-type thermal fuses and varistors achieve instant heat acquisition through internal effective thermocouples and structures. They have multiple protection functions for overvoltage, overcurrent and overtemperature. When the flow or over temperature occurs, the alloy fuse quickly removes the varistor from the circuit to prevent the varistor from continuously overheating and burning.

However, in the above structure, after the alloy of the fuse is blown, there is no effective physical isolation structure between the blown alloy material and the electrodes of the varistor, so that the varistor may still be connected to the circuit, resulting in continuous overheating of the varistor. There is a certain safety hazard in case of fire.

Contents of the invention

In order to solve at least one aspect of the above problems, an embodiment of the present disclosure provides an overheating protection device and a varistor device.

An embodiment of the present disclosure provides an overheating protection device, comprising: a first electrode and a second electrode arranged at intervals; a thermal fuse wire located between the first electrode and the second electrode, the thermal fuse wire and the first electrode The electrode is in electrical contact with the second electrode; and an insulator supports the first electrode and the second electrode, wherein the hot-melt wire melts into a liquid hot-melt material when the ambient temperature reaches a predetermined temperature, and the liquid hot-melt material infiltrates The first electrode and the second electrode, the liquid hot-melt material does not infiltrate at least a portion of the insulator located between the first electrode and the second electrode.

In some embodiments, the insulator includes a flat or corrugated structure, and the first electrode, the second electrode, and the hot-melt wire are arranged on one side of the planar or corrugated structure.

In some embodiments, the overheat protection device further includes: a protective layer, the protective layer and the flat or corrugated structure enclose a cavity, and the cavity accommodates at least a part of the first electrode, At least a part of the second electrode and the hot-melt wire.

In some embodiments, the liquid hot melt material does not wet the protective layer.

In some embodiments, the overheat protection device further includes at least one wetting component, the one wetting component is arranged between the first electrode and the second electrode, the first electrode, the at least one wetting component and The second electrodes are sequentially arranged at intervals along the extending direction of the hot-melt wire, and the liquid hot-melt material infiltrates the wetting component.

In some embodiments, the insulator includes a cylindrical structure, and the first electrode, the second electrode, and the hot-melt wire are arranged in the cylindrical structure.

In some embodiments, at least one of the first electrode and the second electrode is a layered electrode, a columnar electrode or a sponge electrode.

An embodiment of the present disclosure provides a varistor, the varistor includes: a varistor body; and the overheating protection device according to the foregoing embodiment arranged on the varistor body, wherein the insulator is compared to The first electrode and the second electrode are closer to the piezoresistor body.

In some embodiments, the piezoresistor body includes a first electrode layer, a piezoresistor sheet, and a second electrode layer stacked in sequence, and the second electrode layer is disposed opposite to the insulator.

In some embodiments, the varistor includes a thermally conductive layer disposed between the insulator and the second electrode layer.

In some embodiments, the second electrode layer is electrically connected to one of the first electrode and the second electrode, and the varistor further includes: a first pin, the first pin is connected to The first electrode layer is electrically connected; and a second pin is electrically connected to the other of the first electrode and the second electrode.

In some embodiments, the varistor further includes an encapsulation layer, and the encapsulation layer covers the varistor body and the overheat protection device.

Description of drawings

Other objects and advantages of the present invention will be apparent from the following description of the present invention with reference to the accompanying drawings, and may help to provide a comprehensive understanding of the present invention.

FIG. 1 is a schematic plan view of an overheat protection device according to an embodiment of the present disclosure;

Fig. 2 is a schematic cross-sectional structure diagram taken along line aa of Fig. 1;

Fig. 3 is a schematic diagram of the planar structure of the overheat protection device in Fig. 1 after the hot-melt wire is melted;

Fig. 4 is a schematic plan view of an overheat protection device according to another embodiment of the present disclosure;

Fig. 5 is a schematic structural diagram of an overheat protection device according to another embodiment of the present disclosure;

Fig. 6 is a cross-sectional view of Fig. 5 taken from a plane parallel to the Y direction and including the cylinder axis;

Fig. 7 is a schematic cross-sectional structure diagram of a piezoresistor according to an embodiment of the present disclosure.

Detailed ways

The technical solutions of the present invention will be further specifically described below through the embodiments and in conjunction with the accompanying drawings. In the specification, the same or similar reference numerals designate the same or similar components. The following description of the embodiments of the present invention with reference to the accompanying drawings is intended to explain the general inventive concept of the present invention, but should not be construed as a limitation of the present invention.

In addition, in the following detailed description, for purposes of explanation, numerous specific details are set forth in order to provide a comprehensive understanding of the embodiments of the present disclosure. It may be evident, however, that one or more embodiments may be practiced without these specific details.

It should be noted that "on", "formed on" and "arranged on" mentioned in this article may mean that one layer is directly formed or set on another layer, or that a A layer is indirectly formed or disposed on another layer, ie there are other layers between the two layers.

It should be noted that although the terms "first", "second" and the like may be used herein to describe various components, components, elements, regions, layers and/or sections, these components, components, elements, regions, layers and/or parts should not be limited by these terms. Rather, these terms are used to distinguish one component, component, element, region, layer and/or section from another. Thus, for example, a first component, first member, first element, first region, first layer, and/or first portion discussed below could be termed a second component, second member, second element, second region , the second layer and/or the second portion, without departing from the teachings of the present disclosure.

The present disclosure provides an overheat protection device. The overheat protection device includes a first electrode and a second electrode arranged at intervals; a hot-melt wire located between the first electrode and the second electrode; is in electrical contact with the first electrode, the second end of the thermal fuse wire is in electrical contact with the second electrode; and an insulator supports the first electrode and the second electrode. The hot-melt wire melts into a liquid hot-melt material when the ambient temperature reaches a predetermined temperature, and the liquid hot-melt material wets the first electrode and the second electrode, and the liquid hot-melt material does not wet the insulator at least The portion between the first electrode and the second electrode.

The overheat protection device provided by the present disclosure selects the materials of the first electrode, the second electrode and the insulator so that the liquid hot-melt material wets the first electrode and the second electrode and does not wet at least a part of the insulator, thus, when heated After the fusible wire melts when the ambient temperature reaches the predetermined temperature, the liquid hot-melt material gathers at the first electrode and the second electrode spaced apart from each other, which realizes the complete insulation of the first electrode and the second electrode and ensures that the thermal protection device is completely open. state.

Specifically, an embodiment of the present disclosure provides an overheat protection device 100 , FIG. 1 is a schematic plan view of the overheat protection device 100 according to the present disclosure; FIG. 2 is a schematic cross-sectional view taken along line aa in FIG. 1 . As shown in FIGS. 1 and 2 , the overheat protection device 100 includes an insulator 10 , a first electrode 11 and a second electrode 12 on the insulator 10 , and a thermal fuse 13 electrically connecting the first electrode 11 and the second electrode 12 . In this embodiment, the insulator is a flat or corrugated structure (Figure 1 shows an example of a flat structure), the first electrode 11 and the second electrode 12 are located on one side of the insulator 10, and are arranged at intervals from each other. The two ends of 13 are in electrical contact with the first electrode 11 and the second electrode 12 respectively, for example, the two ends of the hot-melt wire 13 are welded to the first electrode 11 and the second electrode 12 respectively.

The hot-melt wire 13 can be made of conductive material with a low melting point, such as tin, aluminum-antimony alloy, tin-bismuth alloy, tin-copper alloy, tin-silver-copper alloy and the like. Thus, when the ambient temperature reaches a predetermined temperature, the thermal fuse wire 13 is melted and disconnected, so that the electrical connection between the first electrode 11 and the second electrode 12 of the overheat protection device 100 is disconnected, and the overheat protection device 100 is in an open state.

The insulator 10 with a flat or corrugated structure can be made of materials such as ceramics, glass, alumina, SiN, polyimide (PI), etc., so as to ensure that the liquid hot-melt material does not infiltrate the insulator 10 . The melting point of the first electrode 11 and the second electrode 12 is higher than that of the hot-melt wire 13 and can be made of materials such as Cu, Ag, Au, Ni, Pd, etc. to ensure that the liquid hot-melt material infiltrates the first electrode 11 and the second insulator. Two electrodes 12. Thus, when the hot-melt wire 13 is melted at the ambient temperature reaching a predetermined temperature, under the action of the surface tension of the liquid hot-melt material, the liquid hot-melt material flows and gathers at the first electrode 11 and the second electrode 12 spaced apart from each other, and the insulator 10 There is basically no liquid hot-melt material on the surface between the first electrode 11 and the second electrode 12. As shown in FIG. The first electrode 11 and the second electrode 12 . In this way, the first electrode 11 and the second electrode 12 are completely insulated, ensuring that the thermal protection device 100 is in a completely open state.

In this embodiment, the first electrode 11 and the second electrode 12 have a layered structure, such as copper pads arranged on one side of the insulator 10 and spaced apart from each other.

In some embodiments, only the part of the insulator 10 located at the first electrode 11 and the second electrode 12 can be set not to be wetted by the liquid hot-melt material.

In some embodiments, in order to avoid external interference on the fluidity of the liquid hot-melt material and ensure the flow of the liquid hot-melt material under the action of surface tension, as shown in FIG. 2 (the protective layer is not shown in FIG. 1 ), The overheat protection device 10 may also include a protective layer 14, the protective layer 14 and the insulator 10 of a flat or corrugated structure form a cavity, and the cavity accommodates at least a part of the first electrode 11, at least a part of the second electrode 12 and a heat sink. Fused wire 13. The protective layer 14 can be made of SiN, polyimide (PI) and other materials, and the liquid hot-melt material does not infiltrate the protective layer 14, thus, the liquid hot-melt material formed after the hot-melt wire 13 is melted can be placed on the surface in the cavity. Convergence towards the first electrode 11 and the second electrode 12 under the action of tension ensures that the fluidity of the liquid hot-melt material is not disturbed by external factors.

In some embodiments, the distance between the first electrode and the second electrode 12 is, for example, greater than or equal to 9 mm, so as to ensure sufficient separation of the liquid hot-melt materials gathered at the first electrode 11 and the second electrode 12 respectively.

FIG. 4 shows a schematic plan view of an overheat protection device according to another embodiment of the present disclosure. The difference between it and the overheat protection device shown in FIG. 1 is that the overheat protection device 10 also includes at least one wetting component 15, for 2 pcs. The wetting component 15 is also arranged on the insulator 10, and is located between the first electrode 11 and the second electrode 12. The first electrode 11, the second electrode 12, and the wetting component 15 are arranged at intervals, for example, as shown in FIG. 4, the first The electrode 11 , the second electrode 12 and the wetting component 15 are all elongated and together form a zebra crossing shape. The wetting component 15 can be made of materials such as Cu, Ag, Au, Ni, Pd, etc., so that the liquid hot-melt material can infiltrate the wetting component 15 . When the hot-melt wire 13 melts into a liquid hot-melt material when the ambient temperature reaches a predetermined temperature, the liquid hot-melt material gathers at the first electrode 11 and the second electrode 12 spaced apart from each other and the wetting component 15, and the liquid hot-melt material separates into each other. The multiple disconnected parts realize complete insulation between the first electrode 11 and the second electrode 12 , and ensure that the thermal protection device 100 is in a completely open state. The overheating protection device in this embodiment can be used in the situation where the volume of the liquid hot-melt material melted by the hot-melt wire 13 is relatively large.

In some embodiments, the wetting component 15 can be made of the same material as the first electrode 11 and the second electrode 12. At this time, the wetting component 15 can be formed on the insulator 10 at the same time as the first electrode 11 and the second electrode 12. In addition, the preparation process is simplified.

In the above embodiments, the first electrode 11 and the second electrode 12 have a layered structure, and in other embodiments, the first electrode 11 and the second electrode 12 may also adopt a columnar structure or a sponge structure.

Those skilled in the art can understand that, although the overheating protection device 100 shown in Fig. 1 and Fig. 4 is generally rectangular, it is not a limitation of the present disclosure, and the overheating protection device 100 can also be in other shapes, such as a circle , rhombus, etc.

Another embodiment of the present disclosure provides an overheat protection device. FIG. 5 is a schematic structural view of an overheat protection device according to this embodiment; FIG. 6 is a cross-sectional view of FIG. 5 taken from a plane parallel to the Y direction and including the cylinder axis . In this embodiment, as shown in Fig. 5 and Fig. 6, the overheat protection device 200 includes an insulator 20, which is different from the foregoing implementation in that the insulator 20 in this embodiment is a hollow tube, and the hollow tube can be a hollow cylinder The structure can also be a hollow square column structure, etc., which is not limited here. In this embodiment, the hollow cylindrical structure shown in FIG. 5 is used as an example for illustration.

The overheat protection device 200 also includes a first electrode 21, a second electrode 22 and a thermal fuse wire 23 housed in the hollow tube body. As shown in FIG. 5, the first electrode 21 and the second electrode 22 are respectively arranged in the hollow tube body close At both ends, there is a predetermined distance between the first electrode 21 and the second electrode 22 , for example, greater than or equal to 9 mm. Two ends of the hot-melt wire 23 are in electrical contact with the first electrode 21 and the second electrode 22 respectively, for example, two ends of the hot-melt wire 23 are respectively welded to the first electrode 21 and the second electrode 22 .

The hot-melt wire 23 can be made of conductive material with a low melting point, such as tin, aluminum-antimony alloy, tin-bismuth alloy, tin-copper alloy, tin-silver-copper alloy and the like. Thus, when the ambient temperature reaches a predetermined temperature, the thermal fuse wire 23 is melted and disconnected, so that the electrical connection between the first electrode 21 and the second electrode 22 of the overheat protection device 200 is disconnected, and the overheat protection device 200 is in an open state.

The insulator 20 with a hollow tubular structure can be made of materials such as ceramics, glass, SiN, polyimide (PI), etc., so as to ensure that the liquid hot-melt material does not infiltrate the insulator 20 . The melting point of the first electrode 21 and the second electrode 22 is higher than the melting point of the hot-melt wire 23 and can be made of materials such as Cu, Ag, Au, Ni, Pd, etc., to ensure that the liquid hot-melt material infiltrates the first electrode 21 and the second insulator. Two electrodes 22 . Thus, when the hot-melt wire 23 is melted when the ambient temperature reaches a predetermined temperature, under the action of the surface tension of the liquid hot-melt material, the infiltrating liquid hot-melt material flows and gathers at the first electrode 21 and the second electrode 22 spaced apart from each other, The insulator 20 is substantially free of liquid hot melt material on the inner surface between the first electrode 21 and the second electrode 22 . When the first electrode 21 and the second electrode 22 are completely insulated, it is ensured that the thermal protection device 200 is in a completely open state.

In this embodiment, both the first electrode 21 and the second electrode 22 may be plate-shaped structures, and they form a closed space with the hollow tube-shaped insulator 20 .

In some embodiments, the first electrode 21 and the second electrode 22 can also use sponge electrodes, which are electrode blocks with a porous structure, so that the liquid hot-melt material is more easily adsorbed on the first electrode 21 and the second electrode 22 , ensure that the first electrode 21 and the second electrode 22 are completely insulated, and ensure that the thermal protection device 200 is in a completely open state.

An embodiment of the present disclosure provides a piezoresistor, which may be an overheating protection piezoresistor, and FIG. 7 shows a schematic cross-sectional structure diagram of the piezoresistor. As shown in FIG. 7 , the piezoresistor 1000 includes a piezoresistor body 300 and an overheating protection device disposed on the piezoresistor electronic body 300 . The overheating protection device can adopt various overheating protection devices in the foregoing embodiments. Here, only the overheat protection device 100 shown in FIGS. 1 and 2 is taken as an example for illustration.

As shown in FIG. 7 , the piezoresistor body 300 includes a first electrode layer 31 , a piezoresistor sheet 32 and a second electrode layer 33 stacked in sequence. The varistor 32 can be a metal oxide varistor, such as a zinc oxide varistor. The piezoresistor sheet can be in various shapes such as a circle and a square, which are not specifically limited here. The first electrode layer 31 and the second electrode layer 33 are arranged respectively on both sides of the varistor sheet 32, and the first electrode layer 31 and the second electrode layer 33 can be made of metal materials, such as Cu, Ag, Al and other metals. materials or their alloys. The first electrode layer 31 and the second electrode layer 33 respectively cover two sides of the varistor sheet 32 , and they may have the same shape as the varistor sheet 32 .

The overheating protection device 100 is arranged on the side of the second electrode layer 33 away from the first electrode layer 31, and the insulator 10 of the thermal protection device 100 is arranged on the second electrode layer 33, that is, the first electrode 11 and the second electrode of the overheating protection device 100 12 is located on the side of the insulator 10 away from the second electrode layer 33 .

The varistor 100 also includes a first lead 51 and a second lead 52, wherein the first lead 51 is drawn out from the first electrode layer, the second lead 52 is drawn out from one of the first electrode 11 and the second electrode 12, and the second electrode The layer 33 is electrically connected to the other of the first electrode 11 and the second electrode 12, as shown in FIG. 11 are electrically connected by a wire 53, and the two ends of the wire 53 can be soldered to the second electrode layer 33 and the first electrode 11 respectively. The first lead 51 and the second lead 52 are used to connect the varistor 1000 to an external circuit.

When the circuit where the varistor 1000 is located is working normally, it will not overheat abnormally, and the temperature cannot reach the fusing condition of the thermal fuse 13 in the varistor 100 , and the varistor 1000 is in a normal working state at this time.

When there is an abnormal voltage in the circuit where the varistor 1000 is located, the varistor 1000 continues to be abnormally overvoltage, or other abnormal conditions cause the temperature of the varistor body 300 to rise, and the varistor body 300 will report to the overheating protection device on it. 100 conducts heat, and when the temperature reaches a predetermined temperature, the hot-melt wire 13 is melted and disconnected, so that the electrical connection between the first electrode 11 and the second electrode 12 of the overheat protection device 100 is disconnected, and the overheat protection device 100 is in an open state. As a result, the circuit where the varistor 1000 is located is in an open state, which prevents the varistor body 300 from continuously overheating and burning.

In this embodiment, as shown in FIG. 7 , the varistor 1000 further includes a heat conduction layer 40 disposed between the second electrode layer 33 and the insulator 10 for conducting heat from the varistor body 300 to the overheat protection device 100 . The heat conduction layer 40 can be a heat conduction adhesive, which can bond and fix the overheat protection device 100 on the second electrode layer 33 while conducting heat. The heat conduction layer 40 can also be solder, which is used for soldering and fixing the overheating protection device 100 on the second electrode layer 33 and plays a role of heat conduction.

Those skilled in the art can understand that the conductive layer 40 is not necessary, and in some embodiments, the thermal conductive layer 40 can be omitted, and the overheat protection device can be directly disposed on the second electrode layer 33 .

In some embodiments, the varistor 1000 may further include an encapsulation layer (not shown in FIG. 7 ), which may integrally cover the combination of the varistor body 300 and the overheating protection device 100 for protecting the package inside. The piezoresistor body 300 and the overheat protection device 100 etc. The first lead 51 and the second lead 52 of the piezoresistor 1000 are drawn out through the packaging layer. The encapsulation layer can use epoxy resin material.

To sum up, in the overheat protection device and the varistor including the overheat protection device provided by the present disclosure, by selecting the materials of the first electrode, the second electrode and the insulator, the liquid hot-melt material can infiltrate the first electrode and the second electrode At least a part of the insulator is not infiltrated, thus, when the hot-melt wire is melted when the ambient temperature reaches a predetermined temperature, the liquid hot-melt material gathers at the first electrode and the second electrode that are spaced apart from each other, realizing the realization of the first electrode and the second electrode. The two electrodes are completely insulated, which ensures that the thermal protection device is in a completely open state, effectively preventing the varistor from continuously overheating and burning.

Although some embodiments of the present general inventive concept have been illustrated and described, those skilled in the art will understand that changes and combinations can be made to these embodiments without departing from the principle and spirit of the present general inventive concept. The scope of the invention is defined by the claims and their equivalents.

Claims (12)

1. a kind of overtemperature protection system characterized by comprising

Spaced first electrode and second electrode；

Heat-fusible conductive wire, between the first electrode and second electrode, the heat-fusible conductive wire and first electrode and second electrode Electrical contact；And

Insulator supports the first electrode and second electrode,

Wherein, the heat-fusible conductive wire is molten into liquid hot melt material, the liquid hot melt when environment temperature reaches predetermined temperature Material infiltrates the first electrode and second electrode, and it is described that the liquid hot melt material does not infiltrate being located at least in for the insulator Part between first electrode and second electrode.

2. overtemperature protection system according to claim 1, wherein the insulator includes tabular or waveform knot The tabular or wavy shaped configuration is arranged in structure, the first electrode, the second electrode and the heat-fusible conductive wire Side.

3. overtemperature protection system according to claim 2, further includes: protective layer, the protective layer and the tabular or Person's wavy shaped configuration surrounds cavity, and the cavity accommodates at least part of the first electrode, and the second electrode is at least A part of and described heat-fusible conductive wire.

4. overtemperature protection system according to claim 3, the liquid hot melt material does not infiltrate the protective layer.

5. overtemperature protection system according to claim 2, wherein the overtemperature protection system further includes at least one infiltration Component, one infiltration component are arranged between the first electrode and second electrode, the first electrode, described at least one Successively sequence interval arranges along heat-fusible conductive wire extending direction for a infiltration component and the second electrode, the liquid hot melt material Infiltrate the infiltration component.

6. overtemperature protection system according to claim 1, wherein the insulator includes tubular structure, first electricity Pole, the second electrode and the heat-fusible conductive wire are arranged in the tubular structure.

7. any overtemperature protection system in -6 according to claim 1, wherein in the first electrode and second electrode At least one is layered electrode, columnar electrode or sponge electrode.

8. a kind of varistor, which is characterized in that institute's varistor includes:

Varistor ontology；And

Any overtemperature protection system in -7 according to claim 1 on pressure-sensitive electronic body is set, wherein it is described absolutely Edge body is compared to the first electrode and second electrode closer to the varistor ontology.

9. varistor according to claim 8, wherein the varistor ontology includes first to be cascading Electrode layer, piezoresistive wafer and the second electrode lay, the second electrode lay and the insulator oppositely facing being arranged each other.

10. varistor according to claim 8, wherein the varistor includes heat-conducting layer, the heat-conducting layer setting Between the insulator and the second electrode lay.

11. varistor according to claim 9 or 10, wherein the second electrode lay and the first electrode and institute An electrical connection in second electrode is stated,

The varistor further include:

First pin, first pin are electrically connected with the first electrode layer；And

Second pin, the second pin are electrically connected with another in the first electrode and the second electrode.

12. according to any varistor in claim 8 to 10, wherein the varistor further includes encapsulated layer, The encapsulated layer coats the varistor ontology and the overtemperature protection system.