JP2001345035A - Protecting element - Google Patents

Abstract

PROBLEM TO BE SOLVED: To aim at obtaining a high heat-resistant property of protecting ele ment such as thermal fuse, a fuse with a resistor, a current fuse, and a fuse for the temperature and for the current or the like wherein an alloy of a low melting point is coated with flux and sealed by top/bottom insulating resin films. SOLUTION: In the protecting element wherein an alloy 3 of a low melting point is connected between leads 1, 2 and in which the alloy of a low melting point 3 is coated with a flux 4 and which is sealed with the top/bottom insulating resin films 5, 6 having flexibility, at least one of the top/bottom insulating resin films 5, 6 is formed by polyethlene naphthalate, or by a polymer blend or a polymer alloy whose main component is polyethlene naphthalate, or by insulating resin films whose main component is polyethlene naphthalate and into which fillers such as fiber, pigment and calcium carbonate or the like are added.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to a protection element,
More specifically, a temperature fuse having a low-melting alloy that melts at a specific temperature, a fuse with a resistor that has a low-melting alloy and a resistor, and forcibly blows the low-melting alloy by energizing and heating the resistor, The present invention relates to a protection element such as a fuse or a thermal fuse and a current fuse.

[0002]

2. Description of the Related Art A thermal fuse that operates at a specific temperature and cuts off a circuit is used as a protection element for protecting an electric device, an electronic device, and the like (hereinafter, referred to as an electronic device) from overheat damage. This type of thermal fuse uses an insulative thermosensitive pellet that melts at a specific temperature as a thermosensitive material. When the thermosensitive pellet is melted, the movable spring is separated from the fixed contact by the extension of the compression spring. (A)
Using a low-melting alloy that melts at a specific temperature as a temperature-sensitive material,
There is a low melting point alloy type (b) in which a current is supplied to the low melting point alloy and a circuit is interrupted by melting of the low melting point alloy. Also,
There is also a protection element (c) called a fuse with a resistor that includes a low-melting alloy and a resistor, and forcibly blows the low-melting alloy by heating the current flowing through the resistor. There is also a current fuse (d) that blows due to overcurrent. Further, there is a so-called thermal fuse / current fuse (e) which is a thermal fuse in which the low melting point alloy melts at a specific temperature and is also a current fuse which melts due to overcurrent.

[0003] The present invention relates to the improvement of the b-type thermal fuse, the c-type fuse with resistor, and the protection element called a current fuse (d) or a thermal fuse / current fuse (e). There will be described below mainly those of the b type and the c type. Examples of the b-type protection element include, for example, Japanese Utility Model Laid-Open No. 57-141346.
No. 6,086,045. The c-type protection element is disclosed in, for example, Japanese Utility Model Laid-Open No. 58-52848. In addition, there is a type in which the b-type and c-type protection elements have a thin structure using an insulating substrate such as a ceramic.

First, a protection element D called a b-type thin thermal fuse will be described with reference to FIGS. 10 and 11. FIG. FIG. 10 is a plan view in which a part of a protection element D called a conventional thin thermal fuse is cut open, and FIG. 11 is a longitudinal sectional view along a center line in the longitudinal direction. 10 and 11, reference numeral 61 denotes a rectangular insulating substrate made of alumina ceramic or the like, and a silver (hereinafter, Ag) paste and a silver-palladium (hereinafter, A) are provided at both ends in the longitudinal direction.
g-Pd) paste or silver-platinum (hereinafter Ag-Pt)
A conductive paste such as a paste is applied and fired to form a pair of electrodes 6.
2, 63 are formed. Leads 64 and 65 are connected to the outer ends of the electrodes 62 and 63 by solders 66 and 67, respectively. Further, a low melting point alloy 68 that melts at a specific temperature is connected to the inner ends of the electrodes 62 and 63 by welding or the like, and the surface of the low melting point alloy 68 is covered with a flux 69. The flux 69 is covered with an insulating cap 70 formed of an insulating material such as ceramic or epoxy resin from above, and sealed with a sealing resin 71 such as epoxy resin.

The protection element D includes, for example, leads 64 and 6
5 is connected to the electronic device in series, so that the lead 64 is connected.
-Electricity is supplied to the electronic device through the electrode 62-the low melting point alloy 68-the electrode 63-the lead 65. Due to an abnormality in electronic equipment,
When the ambient temperature rises, first, the flux 69 melts and cleans and activates the surface of the low melting point alloy 68,
Prepare for melting of low melting point alloy 68. When the ambient temperature further rises and reaches the melting point of the low melting point alloy 68, the low melting point alloy 68
Is melted and attracted to the electrodes 62 and 63 by surface tension to become spheroidized low-melting alloys 68a and 68b (not shown), so that the circuit is cut off and the power supply to the electronic device is cut off. As a result, even if the ambient temperature drops,
The spheroidized low-melting alloys 68a and 68b do not restore their original shape, so that the circuit remains interrupted and functions as a so-called non-return type protection element.

[0006]

In recent years, there has been a remarkable reduction in the size and weight of electronic devices, and there has been a demand for a reduction in the size and size of protection elements such as thermal fuses. However, in the protection element D called a thermal fuse, the insulating substrate 61
Since the insulating cap 70 and the insulating cap 70 are formed of a molded body made of ceramic or insulating resin, their thickness reduction is limited to ensure mechanical strength, and the limit is 200 to 300 μm. Therefore, the thickness of the entire protection element D is inevitably determined by the thickness of the insulating substrate 61 and the height of the insulating cap 70, and there is a problem that the reduction in thickness is limited.

[0007] The above-mentioned problem is caused not only by the above-mentioned protection element D called a thermal fuse, but also by connecting a low melting point alloy between electrodes formed by applying and baking a conductive paste on an insulating substrate, Similarly, a protection element called a fuse with a resistance, in which a body is provided and the low-melting alloy is forcibly blown off by heat generated by energization of the resistor, similarly occurs.

In addition, a low melting point alloy is connected across electrodes formed by applying and firing a conductive paste on an insulating substrate,
The same applies to a protection element called a current fuse in which a low-melting-point alloy melts by self-heating when a predetermined current or more flows. Further, the same applies to a so-called thermal fuse / current fuse which is a thermal fuse which is blown by an overcurrent exceeding a predetermined level, at the same time as a thermal fuse which blows a low melting point alloy due to an ambient temperature.

Therefore, Japanese Utility Model Application Laid-Open No. 64-233 and the like have proposed using a flexible insulating resin film instead of an insulating substrate or an insulating cap made of a molded body of ceramic or insulating resin. I have. However, the structure described in Japanese Utility Model Application Laid-Open No. 64-233 is formed by laminating an inner layer film having heat resistance and an outer film having self-adhesiveness. There was a problem that there was a limit and the cost was high. Therefore, the present invention provides a protective element such as a temperature fuse, a fuse with a resistor, or a current fuse in which a low-melting alloy connected between leads is covered with a flux and sealed from above and below with a flexible resin film. The purpose is to achieve a reduction in thickness.

[0010]

The present invention uses a flexible upper and lower insulating resin film instead of an insulating substrate or insulating cap made of ceramic, and connects a low melting point alloy between a pair of leads. In a protection element in which a low melting point alloy is coated with a flux and the flexible upper and lower insulating resin films are bonded or fused, at least one of the flexible upper and lower insulating resin films is made of polyethylene naphthalate. It is a protection element characterized by the following.

According to the first aspect of the present invention, a flexible upper and lower insulating resin film, a pair of leads sandwiched between the upper and lower insulating resin films, and a connection astride between the leads are provided. A low-melting alloy and a flux covering the low-melting alloy, wherein the upper and lower insulating resin films are bonded or fused and sealed, and at least one of the upper and lower insulating resin films is made of polyethylene naphthalate. A protection element characterized in that: As described above, when polyethylene naphthalate is used as the flexible upper and lower insulating resin films, the thickness of these films can be reduced to a fraction of the thickness of a ceramic insulating substrate or insulating cap. The thickness can be reduced. In addition, polyethylene naphthalate has higher heat resistance than polyethylene terephthalate and the like, and can be manufactured up to a high-temperature protection element.

According to a second aspect of the present invention, a flexible upper and lower insulating resin film, a pair of leads sandwiched between the upper and lower insulating resin films, and a connection extending between the leads. At least one of the flexible upper and lower insulating resin films is a protective element having a low melting point alloy and a flux covering the low melting point alloy, wherein the upper and lower insulating resin films are bonded or fused and sealed. Is a protection element characterized by comprising a polymer blend or a polymer alloy containing polyethylene naphthalate as a main component and one or more polymers mixed therein. As described above, when polyethylene naphthalate is used as a main component and one or more polymers are mixed with the main component, other properties can be improved while maintaining the heat resistance of polyethylene naphthalate.

According to a third aspect of the present invention, an upper and lower insulating resin film having flexibility, a pair of leads sandwiched by the upper and lower insulating resin films, and a connection astride between the leads. In a protective element having a low melting point alloy and a flux covering the low melting point alloy, wherein the upper and lower insulating resin films are bonded or fused and sealed, at least one of the upper and lower insulating resin films is made of polyethylene naphthalate. Is a main component, and a filler is added thereto. As described above, when polyethylene naphthalate is used as a main component and one or more fillers are mixed with the main component, other characteristics can be improved while maintaining the heat resistance of polyethylene naphthalate.

According to a fourth aspect of the present invention, an upper and lower insulating resin film having flexibility, a pair of leads sandwiched by the upper and lower insulating resin films, and a connection astride between the leads. A protective element having a low melting point alloy and a flux covering the low melting point alloy, wherein the upper and lower insulating resin films are bonded or fused and sealed, both of the upper and lower insulating resin films are polyethylene naphthalate, A polymer blend or a polymer alloy containing polyethylene naphthalate as a main component and one or more polymers mixed therein, or a material selected from polyethylene naphthalate as a main component and a filler added thereto. It is a protection element characterized by the following. In this way, both the upper and lower insulating resin films
The use of the same material reduces the number of types of materials, facilitates storage of the materials, and eliminates erroneous use of the materials.

The invention according to claim 5 of the present invention is characterized in that the low melting point alloy and the flux are surrounded by a flexible frame-shaped intermediate insulating film. It is a protection element of description. As described above, when the low-melting alloy and the flux are surrounded by the flexible frame-shaped intermediate insulating film, the flux can be prevented from spreading more than necessary at the time of applying the flux, and the amount of the flux used is required. Not only can it be minimized, but also the adhesion or fusion sealing area of the upper and lower insulating resin films can be sufficiently obtained to improve the sealing property and obtain high moisture resistance. In addition, when the low melting point alloy is melted, the flow space of the melted low melting point alloy is secured by the thickness of the interposed intermediate insulating film, and the fusing operation of the low melting point alloy is ensured.

The invention according to claim 6 of the present invention is the protection element according to any one of claims 1 to 4, wherein the lead is made of copper or nickel. Thus, in the case of a copper lead, not only mechanical connection such as screwing, but also connection by soldering becomes possible. In the case of a lead made of nickel, not only mechanical connection such as screwing, but also connection by welding becomes possible, and the connection work of the lead can be sped up.

The invention according to claim 7 of the present invention is characterized in that the protection element is any one of a thermal fuse, a fuse with a resistor, a current fuse, and a thermal fuse and a current fuse. A protection element according to any one of the above. In this way, a thermal fuse, a fuse with a resistor, a current fuse, or a thermal fuse and a current fuse having excellent heat resistance and a reduced thickness can be obtained.

An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a plan view of a protection element A comprising a thermal fuse according to a first embodiment of the present invention, in which a part of the protection element A is cut out, and FIG. 2 is a sectional view taken along a longitudinal center line in FIG. is there. 1 and 2, reference numerals 1 and 2 denote plate-like leads made of copper or nickel, and a plate-like low-melting alloy 3 which melts at a predetermined temperature across the inner ends of these leads 1 and 2 is welded. And so on. The entire surface of the low melting point alloy 3 and the inner ends of the leads 1 and 2 are covered with a flux 4. Reference numerals 5 and 6 denote flexible upper and lower insulating resin films made of polyethylene naphthalate (PEN), respectively.
The adhesive layers formed on the contact surfaces of the upper and lower insulating resin films 5 and 6 are adhered to each other by covering the inner end portions of the leads 1 and 2 from above and below, or It is sealed by an adhesive interposed between the contact surfaces, or is further sealed by heating the peripheral portions of the upper and lower insulating resin films 5 and 6.

Prior to the connection of the low melting point alloy 3, for example, an Ag layer or a solder layer may be formed on the entire surfaces of the leads 1 and 2 or at least on the inner ends thereof. By doing so, there is an advantage that the connection of the low melting point alloy 3 to the inner ends of the leads 1 and 2 is facilitated, the connection strength is increased, the connection resistance can be reduced, and the internal resistance as a protection element can be reduced. . Particularly, when the low melting point alloy 3 is connected to the inner ends of the leads 1 and 2 after the leads 1 and 2 are fixed to the lower insulating resin film 6, for example, Ag is applied to the entire surface of the leads 1 and 2 or at least the inner end. By forming a layer or a solder layer, the connection temperature of the low melting point alloy 3 can be lowered and the heating time can be shortened, so that the lower insulating resin film 6 is not damaged, and the productivity can be improved.

The above-mentioned protection element A is connected in series with the electronic equipment by connecting its leads 1 and 2 to the terminals of the electronic equipment by means of screws, soldering, welding, etc. If the electronic device is installed at a location where the rise is desired to be detected, the electronic device can be energized via the protection element A. Further, if the temperature of the electronic device rises to near the melting point of the low melting point alloy 3 due to the occurrence of an abnormality due to a short circuit or the like of the electronic device, the flux 4 covering the entire surface of the low melting point alloy 3 melts, The surface of the melting point alloy 3 is cleaned and activated, and the low melting point alloy 3 is ready for melting. When the temperature further rises, the low melting point alloy 3 melts,
It is made spherical by the surface tension and drawn to the leads 1 and 2. As a result, the leads 1 and 2 become non-conductive, and the circuit is opened. As a result, the power supply to the electronic device is stopped, and a further rise in the temperature of the electronic device is prevented, so that overheating damage to the electronic device or a fire resulting therefrom is prevented. In addition, even if the temperature of the electronic device is lowered by stopping the power supply to the electronic device, the low melting point alloy that has been made into a spherical shape does not return to its original state, so that it functions as a so-called non-return type protection element and is safe. . That is, the protection element A performs the same operation as the conventional protection element.

When the upper and lower insulating resin films 5 and 6 are made of polyethylene naphthalate as described above, the upper and lower insulating resin films 5 and 6 can be compared with the protective element D using the ceramic insulating substrate 61 and the insulating cap 70 shown in FIGS. The thickness of the upper and lower insulating resin films 5 and 6 can be reduced to about 50 μm and about 、 to １ ／, respectively, so that the thickness of the entire protection element A can be reduced to about 400 μm.

Furthermore, when the upper and lower insulating resin films 5 and 6 are formed of polyethylene naphthalate as described above, the upper and lower insulating resin films 5, 6 are melted when the low melting point alloy 3 is melted due to the excellent heat resistance of polyethylene naphthalate. Does not melt, and the molten high-temperature low-melting-point alloy 3 squirts out of the holes formed by the melting of the upper and lower insulating resin films 5 and 6 to short-circuit the conductors of the electronic device, Is melted to cause insulation failure. Alternatively, a protection element in a high-temperature operation region, which cannot be realized by conventional upper and lower insulating resin films such as polyethylene terephthalate, can be obtained.

Next, various characteristics such as melting point and heat deformation temperature of polyethylene naphthalate (PEN) will be described with reference to Table 1 in comparison with conventional polyethylene terephthalate (PET).

[0024]

[Table 1]

From Table 1 above, the polyethylene naphthalate (PEN) of the present invention has a melting point 26 ° C. higher, a heat distortion temperature 30 ° C. higher, and a glass transition point of 51 ° C. as compared with conventional polyethylene terephthalate (PET). ° C is also high. From these data, it was found that polyethylene naphthalate (PEN)
It can be seen that the heat resistance is excellent. Further, it is understood that polyethylene naphthalate (PEN) is remarkably excellent in various properties such as oxygen permeability, strength retention and heat shrinkage.

[0026]

Next, a protection element according to an embodiment of the present invention will be described. Copper lead 1, 3mm wide x 0.1mm thick,
2 between the inner ends, width 1 mm x thickness 0.2 mm, melting point 1
83 ° C. low melting point alloy 3 (Sn: 63% by weight, Pb: 37
Wt.%) By welding, applying flux 4, and applying a 150 μm thick polyethylene naphthalate (P
EN), a protection element A of the present invention fused and sealed with upper and lower insulating resin films 5 and 6, and a protection element of a comparative example under the same conditions except that the upper and lower insulating resin films are made of polyethylene terephthalate (PET). Prepare 10 each,
An operation test was conducted in which the low-melting point alloy 3 was melted by raising the temperature at a rate of 1 ° C./min in an oven.
In the protection element A of the present invention, the number of spouts was 0, whereas in the comparative example, 3 was ejected. in this way,
The large difference in heat resistance is due to the fact that the polyethylene naphthalate (PEN) of the present invention has a higher melting point and higher heat distortion temperature than the conventional polyethylene terephthalate (PET), as described above. As described above, the present invention provides the flexible upper and lower insulating resin films 5 and 6 as polyethylene naphthalate (PE) having excellent heat resistance.
Since N) is employed, it is possible to provide a protection element in a high-temperature operation region, which cannot be realized by a conventional insulating film made of polyethylene terephthalate (PET).

Here, the upper and lower insulating resin films 5 and 6 contain not only the above-mentioned polyethylene naphthalate (PEN) but also polyethylene naphthalate (PEN) as a main component and a mixture of one or more other polymers. A polymer blend or polymer alloy may be used. Further, a material containing polyethylene naphthalate (PEN) as a main component and one or more fillers such as fiber (improved heat resistance and strength), pigment (colored), and calcium carbonate (improved moldability) may be added. . In particular, in the case where glass fiber or carbon fiber is added, the heat deformation temperature reaches 300 ° C. or more, and coloring with a pigment can be performed at a glance by, for example, changing the color according to the operating temperature of the protective element. This makes it easy to distinguish different types of products when a large number of protective elements are packaged together, and if different types of products are mixed, it can be instantly detected from the difference in color. Also at the time of assembling, it is possible to prevent components having different operating temperatures from being incorporated by mistake. Further, in the above embodiment, the case where the same material is used for the upper and lower insulating resin films 5 and 6 has been described, but different materials may be used for the upper insulating resin film 5 and the lower insulating resin film 6.

When the leads 1 and 2 are made of copper,
The lead can be mechanically connected to the electronic device by screwing or the like, or can be connected by soldering. When the leads 1 and 2 are made of nickel, the leads can be mechanically connected to the electronic device by screwing or the like, but can be connected in a short time by resistance welding, and the heat generated when the leads are connected is low. Not only can the melting point alloy 3 be prevented from being erroneously melted, but also the productivity of the protective element can be improved.

It is another object of the present invention to provide a protective element which is more excellent in heat resistance and thinner than the conventional one, but has a smaller mounting area than a thinner protective element. If a higher priority is given, a low melting point alloy having a round or flat cross section may be used.

[0030]

Embodiment 2 Next, a protection element B according to a second embodiment of the present invention will be described. The protection element B according to the second embodiment includes:
A frame-shaped intermediate insulating resin film is used in addition to the upper and lower insulating resin films. FIG. 3 is a plan view in which a part of the protection element B of the second embodiment is cut out, and FIG. 4 is a cross-sectional view along a longitudinal center line in FIG. 3 and 4, reference numerals 11 and 12 denote plate-like leads made of copper or nickel, and a low melting point alloy 13 is connected between inner ends thereof by welding or the like. The entire surface of this low melting point alloy 13 is flux 1
4. The periphery of the flux 14 is surrounded by a frame-shaped intermediate insulating resin film 15 having flexibility. Then, from above and below the intermediate insulating resin film 15, similarly to the above, a polymer blend or polymer containing polyethylene naphthalate (PEN) or polyethylene naphthalate (PEN) as a main component and mixed with one or more other polymers Alloy,
Or polyethylene naphthalate (PEN) as the main component, fiber (heat resistance, strength improvement), pigment (coloring),
It is covered with flexible upper and lower insulating resin films 16 and 17 to which one or more fillers such as calcium carbonate (improved formability) are added, and sealed by adhesion or fusion.

According to the above configuration, not only the same operation as the protection element A of the first embodiment can be obtained, but also the provision of the frame-shaped intermediate insulating resin film 15 enables Film 15 with flux 14
By adopting a manufacturing method in which the flux 14 is adhered to the lower insulating resin film 17 before application, the flux 14 is poured into the concave portion formed by the frame-shaped intermediate insulating resin film 15 so that the flux 14 becomes unnecessary. Since the coating can be performed without spreading, the amount of the flux used can be minimized, and the sealing property of the upper and lower insulating resin films 5 and 6 is not impaired by the spread flux. Moreover, as the protection element B as a product, the presence of the frame-shaped intermediate insulating resin film 15
The flow space of the molten low melting point alloy 13 is secured around the low melting point alloy 13, and the low melting point alloy 13 can be reliably blown. The frame-shaped intermediate insulating resin film 15 is
The upper and lower insulating resin films 15 and 16 are preferably made of the same material, but may be made of another material having high adhesiveness or the like.

[0032]

Embodiment 3 Next, a protection element C according to a third embodiment of the present invention will be described. The protection element C according to the third embodiment includes:
The present invention relates to a so-called fuse with resistance, comprising a low-melting alloy and a resistor for forcibly blowing the low-melting alloy by current generation. FIG. 5 is a plan view in which a part of the protection element C according to the third embodiment is cut out, and FIG.
FIG. 7 is a cross-sectional view taken along X-ray, and FIG.

In FIGS. 5 to 7, reference numeral 21 denotes the above-mentioned polyethylene naphthalate (PEN) or a flexible insulating base film containing the same as a main component, and is disposed at eccentric positions near both ends in the longitudinal direction. Holes 22 and 23 are formed. One end of the surface of the insulating base film 21, the position not including the through hole 23, and the other end of the through hole 22.
And electrodes including copper, nickel, a copper alloy, a nickel alloy, and the like, are formed at the position including the through hole 23 and the position including the through hole 23 at one end. In addition, copper, nickel, and copper are located at positions including the through holes 22 and 23 at both ends of the back surface of the insulating base film 21 in the longitudinal direction.
Electrodes 27 and 28 made of a copper alloy, a nickel alloy or the like are formed. The electrodes 24, 25, 26, 2
A gold layer or a solder layer may be formed on each of the layers 7 and 28.

Here, the electrode 25 on the front side of the insulating base film 21 and the electrode 27 on the back side are connected via a conductor in the through-hole 22. The electrode 26 and the electrode 28 on the back side are connected via a conductor in the through hole 23. The through holes 22 and 23 are tapered from both sides of the insulating base film 21 or from either side thereof, and the through holes 22 and 23 are roughened by wet blasting or wet honing. The electrodes 24, 25, 26, 27, and 28 are formed by forming a copper plating layer by electroless plating and then forming a copper plating layer on the copper plating layer by electrolytic plating. Is formed, the electrode 2 on the surface side of the insulating base film 21 is formed.
4, 25, 26 and the electrodes 27, 28 on the back side can be formed at the same time.
Connection conductors connected in the insides 2 and 23 can be formed at the same time.

For example, ruthenium oxide (R) extends across the electrodes 27 and 28 on the back surface of the insulating base film 21.
uO) or the like is deposited, sputtered or plated to form a film-shaped resistor 29. Note that a chip resistor can be used instead of the resistor 29.

Returning to the front side again, leads 30, 31, 32 made of a copper plate material or a nickel plate material are fixedly connected to the electrodes 24 to 26 by soldering or the like. Further, a low melting point alloy 33 is connected between the inner ends of the leads 30 and 31 by welding or the like. Further, the surface of the low melting point alloy 33 is covered with a flux 34.

The upper and lower insulating resin films 35 and 36 are covered from above the flux 34 and from below the resistor 29, respectively, and the peripheral edges of the upper and lower insulating resin films 35 and 36 are bonded with an adhesive. It is bonded or fused and sealed by thermocompression bonding or the like. The leads 30, 31, and 32 correspond to the upper and lower insulating resin films 3 respectively.
Since fusion sealing cannot be performed at steps 5 and 36, the sealing is performed using a resin adhesive or the like.

In the protection element C of the third embodiment,
Insulating base film 21 and upper and lower insulating resin film 3
5 and 36 are made of either polyethylene naphthalate or a polymer blend or polymer alloy containing polyethylene naphthalate as a main component and a polymer, or a material containing polyethylene naphthalate as a main component and a filler added, and having flexibility. Because I made it a resin film,
The intended effect of the protective element of the present invention is not only high heat resistance and thinness, but also the low melting point alloy 33 can be forcibly blown off by the heat generated by energization of the resistor 29, so The melting point of the low melting point alloy 33 is not required to be as strict as that of the low melting point alloys 3 and 13 which respond to the ambient temperature in the protection elements A and B of the first and second embodiments. The selection range becomes wider,
In addition to being able to use easily available and inexpensive materials, the present invention has a specific function and effect that it can be applied to a new use in which a thermal fuse cannot be used.

Next, an example of how to use the protection element C of the third embodiment will be described. FIG. 8 shows the protection element C described above.
The equivalent circuit diagram of FIG. 8, 40, 41, 42
Denotes terminals, which correspond to the leads 30, 31, and 32, respectively. F is a fuse element corresponding to the low melting point alloy 33, and is connected between the terminals 40 (30) and 41 (31). Further, R is a resistor corresponding to the resistor 29 and is connected between the terminals 41 (31) and 42 (32).

FIG. 9 is a circuit diagram in the case where the protection element C composed of the fuse with a resistor is applied to prevent overcharge of a lithium ion secondary battery. In FIG. 9, reference numerals 51 and 52 denote positive and negative DC input terminals, and 53 and 54 denote positive and negative DC output terminals. The positive DC input terminal 51 is connected to the terminal 4 of the protection element C.
0 (30) is connected, and the positive direct current output terminal 53 is connected to the terminal 41 (31) of the protection element C. Therefore, the fuse element F (fusible alloy 33) of the protection element C is connected between the positive DC input terminal 51 and the positive DC output terminal 53. The negative DC input terminal 52 is connected to the negative output terminal 5.
4 is connected. Reference numeral 55 denotes voltage detecting means for detecting a terminal voltage. In the illustrated example, a zener diode 56 as an example of a voltage detecting element and a current limiting resistor 57 are connected in series, and the cathode of the zener diode 56 is connected to the positive DC output terminal 53. Have been. Reference numeral 58 denotes a switching unit which is brought into a conductive state by the voltage detection of the voltage detection unit 55, and is constituted by a transistor 58 in the illustrated example. The collector of the transistor 58 is connected to the terminal 42 (32) of the protection element C, and the emitter is connected to the negative DC input terminal 52 (negative DC output terminal 54). The other end of the current limiting resistor 47 of the voltage detecting means 45 is connected to a base which is a control terminal of the transistor 58.

When the protection element C is connected as shown in FIG. 9, the leads 30 and 31 are led out in a straight line.
In contrast to the wide shape, only the lead 32 is derived from a different position and is narrow, so that these leads 30, 31, 32, that is, the terminals 40, 4
It is easy to discriminate 1, 42, and there is no erroneous connection.

In the circuit configuration shown in FIG. 9, a power source, for example, a charger 59 is connected to the positive and negative DC input terminals 51 and 52, and a lithium ion secondary battery 60 as a load is connected to the positive and negative DC output terminals 53 and 54. I do. Then, the charger 59-the terminal 51-the terminal 40 (30)-the fuse element F
Current flows through the path of (low melting point alloy 33), terminal 41 (31), terminal 53, lithium ion secondary battery 60, terminal 54, terminal 52, and charger 59, and the lithium ion secondary battery 60 is charged. . As the charging time elapses, the terminal voltage of the lithium ion secondary battery 60 gradually increases.
When the terminal voltage of the lithium ion secondary battery 60 finally reaches the Zener voltage of the Zener diode 56, the Zener diode 56 conducts, a bias current flows between the base and the emitter of the transistor 58, and the transistor 5
8 is turned on. Then, the charger 59-terminal 51-
Terminal 40 (30) -Fuse element F (low melting point alloy 33)
-Terminal 41 (31)-resistor R (resistor 29)-terminal 42
A current flows through the path of (32) -transistor 58-terminal 52-charger 59, and the resistor R (resistor 29) generates heat.
The heat generated by the resistor R (resistor 29) is transmitted to the low-melting alloy 33 (fuse element F) on the front surface via the insulating base film 21, and the low-melting alloy 33 (fuse element F) is blown. Then, charging of the lithium ion secondary battery 60 is stopped, overcharging is prevented, and the resistance R
(Resistor 29) is the fuse element F (fusible alloy 33) 2
Since it is connected to the next side, the current supply to the resistor R (the resistor 29) is also stopped.

Although each of the above embodiments of the present invention has been described with reference to a specific structure, the present invention is not limited to the structure shown in the above embodiment, and does not depart from the spirit of the present invention. It goes without saying that various modifications are possible.

For example, in the protection element A of the first embodiment shown in FIGS. 1 and 2, the leads 1 and 2 are not led out from between the upper and lower insulating resin films 5 and 6, but the through holes are formed in the lower insulating resin film 6. Then, an electrode may be formed on the back surface of the lower insulating resin film 6, and the electrodes on the front and back surfaces may be connected by a conductor in the through-hole, and a lead may be connected to the electrode on the back surface. Alternatively, a through hole may be formed in the lower insulating resin film 6, and the leads 1 and 2 may be led out to the back surface of the lower insulating resin film 6 through the through hole. In this case, since the leads are not interposed in the sealing portions of the upper and lower insulating resin films 5 and 6, the sealing of the upper and lower insulating resin films 5 and 6 is ensured and the moisture resistance is improved.

Further, in the protection elements A, B, and C of the first, second, and third embodiments shown in FIGS. 1 to 7, the upper and lower insulating resin films 5, 6, 16, 17, 35, and 36 are separately provided. In addition to the case where two sheets are used, one insulating resin film can be formed by folding back. By doing so, not only is it easier to position the upper and lower insulating resin films compared to the case where two sheets are used, but also it is possible to reduce the number of bonded or fused portions of the upper and lower insulating resin films by one side. There is a feature that the stopping performance is improved.

Further, in the protection element C according to the third embodiment shown in FIGS. 5 to 7, a description will be given of a case where the resistor 29 is provided on the side opposite to the side of the insulating base film 21 where the low melting point alloy 33 is connected and fixed. However, it may be provided on the same surface side as the fixing surface side of the low melting point alloy 33. In this case, it is desirable to form an insulating layer on the surface of the resistor 29 and form the low melting point alloy 33 on the insulating layer. According to such a configuration, the heat generated by the resistor 29 is quickly transmitted to the low-melting alloy 33 via the thin insulating layer. There is a feature that it can be done. In other words, there is a feature that the low-melting-point alloy 33 can be blown with less heat generated by the resistor 29. In this case, naturally, the through holes 22 and 23 of the insulating base film 21 and the electrodes 27 and 28 on the back surface side of the insulating base film 21 are unnecessary. In some cases, the insulating base film 21 can be omitted.

Also, leads 1, 2, 11, 12, and 3
0 to 32, as long as the current capacity is not impaired, the upper and lower insulating resin films are bonded to each other by narrowing the sealing portion by the upper and lower insulating resin films or by forming through holes or slits in the sealing portion. Alternatively, it is desirable to increase the fusion sealing area. In some cases, leads 1, 2, 11,
A recessed portion by embossing or half-etching may be provided in the sealing portions 12 and 30 to 32 to make the sealing interface uneven so as to improve the sealing property.

[0048]

As described above, the present invention provides a flexible upper and lower insulating resin film, a pair of leads sandwiched between these upper and lower insulating resin films, and a low-powered cable connected between these leads. A protective element having a melting point alloy and a flux covering the low melting point alloy, wherein the upper and lower insulating films are bonded or fused and sealed.
Since the protection element is characterized in that at least one of the upper and lower insulating resin films is made of polyethylene naphthalate, compared to a protection element using an insulating resin film made of conventional polyethylene terephthalate or the like, it has excellent heat resistance. A protection element is obtained.

[Brief description of the drawings]

FIG. 1 is a plan view in which a part of a protection element A according to a first embodiment of the present invention is cut away.

FIG. 2 is a sectional view taken along a longitudinal center line of the protection element A according to the first embodiment of the present invention.

FIG. 3 is a plan view of a protection element B according to a second embodiment of the present invention, which is partially cut away.

FIG. 4 is a sectional view taken along a longitudinal center line of a protection element B according to a second embodiment of the present invention.

FIG. 5 is a plan view of a protection element C according to a third embodiment of the present invention, which is partially cut away.

FIG. 6 is a cross-sectional view of the protection element C according to the third embodiment of the present invention, taken along line XX.
Sectional view along the line

FIG. 7 is a bottom view in which a part of the protection element C according to the third embodiment of the present invention is cut out.

FIG. 8 is an equivalent circuit diagram of a protection element C according to a third embodiment of the present invention.

FIG. 9 is a circuit diagram of an overcharge prevention circuit in which a protection element C according to a third embodiment of the present invention is applied to prevent overcharge of a lithium ion secondary battery.

FIG. 10 is a plan view in which a part of a conventional thin protection element D is cut open.

FIG. 11 is a cross-sectional view of a conventional thin protection element D taken along a longitudinal center line.

[Explanation of symbols]

1, 2, 11, 12, 30, 31, 32 Lead 3, 13, 33 Low melting point alloy 4, 14, 34 Flux 5, 6, 16, 17, 35, 36 Upper and lower insulating resin film 15 Intermediate insulating resin film 21 Insulation Base film 22, 23 Through hole 24, 25, 26, 27, 28 Electrode 29 Resistor (resistive film) 40, 41, 42 Terminal 51, 52 Positive / negative DC input terminal 53, 54 Positive / negative DC output terminal 55 Voltage detecting means 56 Voltage Sensing element (Zener diode) 57 Current limiting resistor 58 Switching means (transistor) 59 Charger 60 Lithium ion secondary battery F Fuse element R Resistance

Claims (7)

[Claims] An upper and lower insulating resin film having flexibility,
A pair of leads sandwiched by these upper and lower insulating resin films, a low-melting alloy connected across these leads, and a flux covering the low-melting alloy, wherein the upper and lower insulating films do not adhere to each other. A protective element which is fusion-sealed, wherein at least one of the upper and lower insulating resin films is made of polyethylene naphthalate. 2. An upper and lower insulating resin film having flexibility,
A pair of leads sandwiched by these upper and lower insulating resin films, a low melting point alloy connected between these leads, and a flux covering the low melting point alloy, wherein the upper and lower insulating resin films are bonded. In the protective element which is sealed by fusion bonding, at least one of the upper and lower insulating resin films is mainly composed of polyethylene naphthalate, and is made of a polymer blend or a polymer alloy in which one or more polymers are mixed. Characteristic protection element. 3. An upper and lower insulating resin film having flexibility,
A pair of leads sandwiched by these upper and lower insulating resin films, a low melting point alloy connected between these leads, and a flux covering the low melting point alloy, wherein the upper and lower insulating resin films are bonded. A protective element, wherein at least one of the upper and lower insulating resin films is mainly composed of polyethylene naphthalate and a filler is added thereto. 4. An upper and lower insulating resin film having flexibility,
A pair of leads sandwiched by these upper and lower insulating resin films, a low melting point alloy connected between these leads, and a flux covering the low melting point alloy, wherein the upper and lower insulating resin films are bonded. Or a fusion-sealed protective element, wherein both of the upper and lower insulating resin films are polyethylene naphthalate, a polymer blend or polymer alloy containing polyethylene naphthalate as a main component and one or more polymers mixed therein, and A protection element characterized in that the element is selected from those containing polyethylene naphthalate as a main component and a filler added thereto. 5. The protection element according to claim 1, wherein the low melting point alloy and the flux are surrounded by a flexible frame-shaped intermediate insulating film. 6. The protection element according to claim 1, wherein said lead is made of copper or nickel. 7. The protection element according to claim 1, wherein the protection element is one of a thermal fuse, a fuse with a resistor, a current fuse, and a thermal fuse and a current fuse.