JP6891148B2 - Protective element - Google Patents

Description

The present disclosure relates to a protective element that protects an electrical device, more particularly a protective element that protects an electrical element or circuit contained in the electrical device.

A PTC element, a thermal fuse element, a current fuse element, or the like is used as a protective element that cuts off the current flow when an overcurrent flows through the electric device. Above all, when used in a cylindrical secondary battery, the polymer PTC element can be arranged by being incorporated in the sealing plate of the secondary battery, which is useful in that the space inside the battery can be effectively used.

Although the polymer PTC device has recoverability, problems may occur depending on the application. For example, when a PTC element is used in a cylindrical lithium ion secondary battery cell used in multiple parallels, the cell may continue to generate heat unless the short-circuited cell using the PTC element is removed. Further, the PTC element has a relatively small rated capacity, which is disadvantageous when a large current is continuously energized.

As a protective element in consideration of such a problem, an insulating layered element having at least one through opening, a conductive metal thin layer located on each main surface of the layered element, and the through opening. A protective element is known that is located on a side surface that defines at least one and has a fuse layer that electrically connects a thin conductive metal layer (Patent Document 1). According to such a protective element, an overcurrent that does not greatly exceed the rated capacity, for example, an overcurrent that is about twice the rated capacity, can be quickly and surely overcurrented while allowing a larger current to flow. It can be blocked.

International Publication No. 2014/034833

In the protective element as described in Patent Document 1, a fuse layer is formed on the side surface of the through opening by plating (particularly, electrolytic plating). The fuse layer has a predetermined cross-sectional area in order to obtain a predetermined fuse function. Such a cross-sectional area can be adjusted by the thickness of the fuse layer, but when the fuse layer is formed by plating on the side surface of the through opening, the thickness may vary by about ± 20%. That is, the resistance value of the protective element, the cutoff time, and the like may vary.

An object of the present disclosure is to provide a protective element having a small variation in resistance value and cutoff time of a fuse layer.

The present disclosure includes the following aspects.
1. 1. Layered elements formed of insulating resin and
It has a conductive metal thin layer provided on at least one of both main surfaces of the layered element.
A protective element in which at least one of the conductive metal thin layers has a fuse pattern.
2. The layered element has at least one through opening and
The conductive metal thin layer is provided on both main surfaces of the layered element.
The conductive metal thin layers provided on both main surfaces of the layered element are electrically connected by a conductive connecting portion passing through the through opening.
The protective element according to the above [1].
3. 3. The protective element according to the above [1] or [2], wherein the layered element is an annular shape having a through opening in the center.
4. The conductive metal thin layer provided on the main surface of one of the annular layered elements is a first annular metal thin layer located on the outer edge side of the annular layered element, that is, the annular layered element. The protective element according to the above [3], comprising a second annular metal thin layer located on the inner edge side and a bridging portion for electrically connecting them.
5. The protective element according to the above [4], wherein the bridging portion is one.
6. The protective element according to the above [4], wherein the bridging portions are present at an equal angle of 2 to 8 with respect to the center of the ring.
7. The protective element according to any one of the above [4] to [6], wherein the distance between the first annular metal thin layer and the second annular metal thin layer is 0.1 mm to 5.0 mm.
8. The protective element according to any one of the above [4] to [7], wherein the width of the first annular metal thin layer is larger than the width of the second annular metal thin layer.
9. The protective element according to any one of the above [1] to [8], wherein the conductive metal thin layer contains a nickel foil or a copper foil.
10. The protective element according to any one of the above [1] to [9], further comprising an insulating layer on a thin conductive metal layer having a fuse pattern so as to cover at least the fuse pattern.
11. An electric device having the protective element according to any one of the above [1] to [10].
12. A sealing body having the protective element according to any one of the above [1] to [10].
13. A secondary battery cell comprising the protective element according to any one of the above [1] to [10].

According to the present disclosure, a protective element having a small variation in the resistance value of the fuse layer and the breaking time is provided.

FIG. 1 schematically shows a protective element according to an embodiment of the present invention. FIG. 2 schematically shows a cross-sectional view of the protective element shown in FIG. 1 along the xx line.

The protective element of the present disclosure will be described in detail with reference to the drawings.

As shown in FIGS. 1 and 2, the protective element 1 of the embodiment of the present disclosure is provided on both the annular layered element 2 formed of the insulating resin and the main surfaces of the layered element 2. It is composed of the conductive metal thin layers 3 and 4, and the conductive connecting portion 5 provided on the inner wall surface of the through opening and electrically connecting the conductive metal thin layers 3 and 4. The conductive metal thin layer 3 on the main surface of one of the layered elements 2 has a bridging portion 6 which is a fuse pattern. The conductive metal thin layer 3 includes a first annular metal thin layer 7 located on the outer edge side of the annular layered element 2, a second annular metal thin layer 8 located on the inner edge, and a bridge that electrically connects them. It consists of a hanging portion 6. The layered element 2, the first annular metal thin layer 7, and the second annular metal thin layer 8 are arranged concentrically. In the protective element 1, the current flows in the order of the first annular metal thin layer 7, the bridging portion 6, the second annular metal thin layer 8, the conductive connecting portion 5, and the conductive metal thin layer 4 (or vice versa). .. When an overcurrent flows through the protective element 1, the bridging portion 6 which is a fuse pattern is blown and the current is cut off.

In the present embodiment, the layered element 2 is an annular shape having a through opening 9 at the center. The through opening 9 penetrates the layered element 2 along the thickness direction of the layered element, and its planar shape (that is, the cross-sectional shape in the direction perpendicular to the thickness direction) is circular.

In the present disclosure, the shape of the layered element, the presence or absence of the through opening, and the shape of the through opening are not limited to those of the present embodiment.

For example, the form of the layered element is not particularly limited as long as the dimension in the thickness direction is smaller than the other dimensions, or is considerably smaller (for example, a sheet-like form). The planar shape of the layered element or the cross-sectional shape in the direction perpendicular to the thickness of the layered element is geometrically axisymmetric and / or point-symmetrical, such as circular, square, rectangular, rhombic, annular (especially circular). It is preferable to have it as a main surface having a shape such as (so-called donut shape). Further, the layered element may be a plate-shaped member having no through opening.

The through opening may or may not be present. If there are such through openings, one or two or more, for example, 2 to 8 may be present. When a plurality of through openings are present, it is preferable that the through openings are evenly present with respect to the center. By arranging them evenly, the length of the current path flowing through the conductive metal thin layer can be made shorter, and the resistance in the conductive metal thin layer can be made smaller.

The planar shape of the through opening may be circular, square, rhombic, rectangular, or elliptical.

The thickness of the layered element 2 is not particularly limited, but is, for example, 0.03 mm to 10 mm, preferably 0.05 mm to 5.0 mm, more preferably 0.1 mm to 2.0 mm, still more preferably 0.1 mm to 1. It can be 0.0 mm, particularly preferably 0.2 mm to 0.5 mm. By setting the thickness of the layered element to 10 mm or less, it is advantageous for miniaturization of the protective element. Reducing the thickness of the layered element is advantageous for further miniaturization, and for example, when the protective element is used in a battery, the volume of the cell can be increased. By setting the thickness of the layered element to 0.03 mm or more, a sufficient withstand voltage between both main surfaces of the layered element can be secured. By increasing the thickness of the layered element, a higher withstand voltage can be obtained and use at a higher voltage becomes possible.

The insulating resin constituting the layered element 2 is not particularly limited as long as it is an electrically insulating resin. Examples of the insulating resin include resins such as polyethylene, polypropylene, polycarbonate, fluororesin, acrylonitrile-butadiene-styrene (ABS) resin, polycarbonate-ABS alloy resin, polybutylene terephthalate (PBT) resin, and elastomer. Be done. Such an insulating resin has the same flexibility as the polymer used for the polymer PTC element, and the protective element of the present invention is suitable for various electric devices, for example, a sealing plate of a secondary battery cell, instead of the polymer PTC element. Can be incorporated into. Particularly preferably, the insulating resin can be polyethylene or polyvinylidene fluoride.

In the present embodiment, conductive metal thin layers 3 and 4 are provided on both main surfaces of the layered element 2, respectively.

The conductive metal thin layer is not particularly limited as long as it is a thin layer of a conductive metal, and can be made of a metal such as nickel, copper, aluminum, or gold. The conductive metal thin layer may be a single layer or may be formed of a plurality of metal thin layers. The conductive metal thin layer may preferably be a nickel foil or a nickel-copper laminate (nickel-copper foil). In the case of nickel-copper foil, the copper foil is preferably located on the insulating resin side.

The thickness of the conductive metal thin layer is not particularly limited, but may be, for example, 0.1 μm to 300 μm, preferably 1.0 μm to 100 μm, and more preferably 5.0 μm to 50 μm. By increasing the thickness of the conductive metal thin layer, the resistance of the conductive metal thin layer can be further reduced. On the other hand, by making the thickness of the conductive metal thin layer smaller, the thickness of the protective element can be made smaller, which is advantageous for miniaturization.

The layered element in which the conductive metal thin layer is located on each main surface is obtained by simultaneously extruding the insulating resin constituting the layered element together with the metal sheet (or metal leaf) constituting the metal thin layer. It can be produced by obtaining an extruded product in which an insulating resin is sandwiched between thin layers of conductive metal. In another embodiment, the insulating resin layered material can be obtained, for example, by extrusion, the layered material can be sandwiched between thin conductive metals, and these can be integrally thermocompression bonded to obtain a crimped material. it can. In yet another embodiment, it can be produced by forming a plating layer on a layered element.

In the present embodiment, the conductive metal thin layer 3 is an electric first annular metal thin layer 7 located on the outer edge side of the annular layered element 2, a second annular metal thin layer 8 located on the inner edge side, and the like. It is composed of a bridge portion 6 that is connected to the target. The first annular metal thin layer 7 and the second annular metal thin layer 8 are arranged concentrically with the layered element 2. On one main surface of the layered element, the first annular metal thin layer 7 occupies a region from the outer edge to the inside to a predetermined distance, and the second annular metal thin layer 8 is predetermined from the inner edge to the outside. Occupies the area up to the distance. The first annular metal thin layer 7 and the second annular metal thin layer 8 are not in direct contact with each other, and four bridging portions 6 bridge them and are electrically connected. The bridging portion 6 corresponds to a fuse pattern and blows when an overcurrent flows through the protective element to cut off the current.

In the protective element of the present disclosure, the fuse pattern means a pattern configured to blow in response to an overcurrent or abnormal heat generation. Therefore, the shape is not particularly limited as long as it fulfills such a function.

In the present embodiment, the width of the first annular metal thin layer 7 is larger than the width of the second annular metal thin layer 8. By increasing the width of the first annular metal thin layer 7, it becomes easy to fix the protective element 1 when it is attached to another component, and the pressure when it is fixed outside the protective element is increased. The effect on the bridge can be reduced.

The width of the first annular metal thin layer 7 is not particularly limited, but may be, for example, 1.0 mm to 20 mm, preferably 2.0 mm to 15 mm, and more preferably 5.0 mm to 10 mm. By increasing the width of the first annular metal thin layer 7, the contact area can be increased when the protective element 1 is electrically connected to another electric element in the first annular metal thin layer 7. The connection becomes easy, and the resistance at the connection point becomes easy to reduce.

The width of the second annular metal thin layer 8 is not particularly limited, but may be, for example, 0.1 mm to 18 mm, preferably 0.5 mm to 10 mm, and more preferably 1.0 mm to 8.0 mm.

The distance between the first annular metal thin layer and the second annular metal thin layer is not particularly limited as long as the insulation distance can be secured, but is, for example, 0.1 mm to 5.0 mm, preferably 0.5 mm. It can be ~ 3.0 mm. By increasing the distance between the first annular metal thin layer and the second annular metal thin layer, the insulation between the first annular metal thin layer and the second annular metal thin layer can be further ensured. Can be done. In addition, it is possible to more reliably prevent the bridge portion 6 from being reconnected after being blown. By reducing the distance between the first annular metal thin layer and the second annular metal thin layer, the length of the bridging portion can be reduced, and the resistance of the bridging portion can be reduced.

The length of the bridging portion 6 (the length from the position of contact with the first annular metal thin layer to the position of contact with the second annular metal thin layer) is the length of the first annular metal thin layer and the second annular metal thin layer. It is substantially equal to the distance between the annular metal thin layers of. That is, the length of the bridging portion 6 is not particularly limited, but may be, for example, 0.1 mm to 5.0 mm, preferably 0.5 mm to 3.0 mm.

The width of the bridging portion 6 is not particularly limited, but may be, for example, 0.1 mm to 5.0 mm, preferably 0.5 mm to 3.0 mm.

In the present embodiment, the number of the bridge portions 6 is 4, but the number is not particularly limited.

In one embodiment, there is one bridge. By using only one bridging portion, the bridging portion can be blown faster and more reliably when the protective element operates. In addition, after the bridging portion is blown, the insulation distance at the fused portion can be secured more reliably.

In another embodiment, the number of bridging portions may be two or more, for example 2 to 8, more preferably 3 to 6. By increasing the number of bridging portions, for example, by increasing the number to two or more, the rated current can be further increased, and the generation of an arc can be suppressed. Further, by increasing the number of bridging portions, the mechanical strength of the protective element can be increased.

When there are a plurality of the bridging portions, the bridging portions are arranged at an equal angle with respect to the center of the annulus. By arranging the bridging portion at an equal angle with respect to the center of the annulus, the length of the current path flowing through the conductive metal thin layer can be shortened, and the resistance in the conductive metal thin layer can be further reduced. it can.

In the protective element of the present disclosure, an insulating layer may be provided at least a part of the thin metal layer having the fuse pattern.

In one embodiment, the insulating layer is provided so as to cover a fuse pattern (a bridging portion in the above embodiment). By covering the fuse pattern with an insulating layer, it is possible to prevent metal from scattering during fusing.

In one embodiment, the insulating layer is an annular shape concentric with the layered element 2 and is provided so as to cover from the inner edge of the annulus of the layered element to the outside of the bridge portion (that is, the fuse pattern). Preferably, the distance between the outer edge of the insulating layer and the end of the bridging portion (the outer edge of the annulus) can be 0.1 to 2.0 mm.

The insulating layer is provided so that a part of the thin metal layer is exposed. The protective element of the present disclosure can be connected to other electrical elements in the exposed portion of the thin metal layer.

In a preferred embodiment, the insulating layer is an annular shape concentric with the layered element 2 and covers from the inner edge of the annulus of the layered element to the outside of the bridging portion (that is, the fuse pattern), and the annular metal thin layer is formed. , Is provided so as to be exposed in a region at a predetermined distance from the outer edge.

The thickness of the insulating layer is not particularly limited, but may be, for example, 1 μm to 50 μm, preferably 5 μm to 15 μm.

The insulating resin constituting the insulating layer is not particularly limited as long as it is an electrically insulating resin, but a resin having high heat resistance, for example, a solder resist or the like is preferable.

The protective element 1 is located on the side surface defining the through opening 9, and is a conductive connecting portion 5 that electrically connects the conductive metal thin layers 3 and 4 located on both main surfaces of the layered element 2. Have. That is, the conductive metal thin layers 3 and 4 are electrically connected by a conductive connecting portion 5 passing through the through opening 9.

The conductive connecting portion 5 is preferably a conductive layer. The conductive connecting portion 5 may be a single layer, or may be composed of two or more layers, for example, two layers, three layers, or four layers.

The material constituting the conductive connecting portion 5 is not particularly limited as long as it is conductive, but may be, for example, a metal such as nickel, copper, aluminum, or gold.

The conductive connecting portion 5 is preferably formed by plating.

The thickness of the conductive connecting portion 5 is not particularly limited as long as it is not melted before the bridging portion. The thickness of the conductive connecting portion 5 can be, for example, 1.0 μm to 500 μm, preferably 5.0 μm to 300 μm, and more preferably 10 μm to 200 μm. By setting the thickness of the conductive connecting portion 5 to 1.0 μm or more, the resistance of the conductive connecting portion 5 can be reduced. Further, by setting the thickness of the conductive connecting portion 5 to 500 μm or less, the formation of the conductive connecting portion 5 becomes easy. In particular, when the conductive connection portion 5 is formed by plating, the formation of the conductive connection portion 5 becomes easier by setting the thickness of the conductive connection portion 5 to 20 μm or less.

In one embodiment, the protective element of the present disclosure is obtained by forming a conductive metal thin layer on the main surface of the layered element, and then removing a part of the conductive metal thin layer to form a fuse pattern. Can be done.

In a preferred embodiment, the protective element of the present disclosure is
The process of forming a through opening in a layered element,
The process of attaching a thin layer of conductive metal to both main surfaces of a layered element,
A step of forming a fuse pattern by etching at least one conductive metal thin layer,
It can be manufactured by a method including a step of forming a conductive connecting portion in the through opening and electrically connecting the conductive metal thin layers on both main surfaces.

Since the protective element of the present disclosure has a conductive metal thin layer having a fuse pattern on the main surface of the layered element, it is easy to adjust the thickness of the fuse pattern. In particular, by arranging a metal foil in which a conductive metal thin layer is prepared separately from the layered element on the layered element and then forming a fuse pattern, it becomes easier to control the thickness. Therefore, in the protective element of the present disclosure, variations in resistance value, cutoff time, etc. are suppressed.

(Example)
The protective elements of the present disclosure shown in FIGS. 1 and 2 were manufactured except that two bridging portions 6 were provided symmetrically. Specifically, the protective element was manufactured as follows.

First, a sheet was prepared in which an insulating resin to be a layered element was sandwiched between two thin conductive metal layers. As the conductive metal thin layer, a Ni thin layer having a thickness of 25 μm was used, and as the layered element, polyethylene having a thickness of 400 μm was used.

Next, a through opening having a diameter of 6.0 mm was formed on the sheet. After that, a part of one conductive metal thin layer (the part to be removed by later etching) is exposed, and an etching resist is formed so as to cover the other part, and then the conductive metal thin layer of the exposed part is exposed by etching. Was removed to form a slit. The width of the slit, that is, the distance between the first annular metal thin layer and the second annular metal thin layer was 0.4 mm. The width of the second annular metal thin layer was 0.8 mm, and the width of the bridging portion was 0.6 mm.

Next, the above-mentioned etching resist was removed, and a chemical copper plating layer was formed on the entire sheet by electroless plating. Then, the parts other than the through opening were masked, and an electrolytic copper plating layer was further formed by electrolytic plating on the chemical copper plating layer of the through opening.

Then, the above mask was removed, and the chemical copper plating layer exposed on the main surface of the sheet was removed by etching. Then, the entire sheet was nickel-plated. By such a plating treatment, a nickel plating layer was formed on the entire sheet except for the portion where the insulating resin was exposed.

Finally, the protective element of the present disclosure was obtained by punching so as to form a disk having a diameter of 14.6 mm, which is concentric with the through opening.

(Comparison example)
As a comparative example, a protective element of the comparative example was manufactured by forming a fuse layer by plating on the side surface of the through opening without a slit.

(Evaluation)
-Resistance value For the protective element of the present disclosure, the resistance value between the first annular metal thin layer and the conductive metal thin layer on the main surface facing it, and for the protective element of the comparative example, the position corresponding to the above. The resistance value between the thin layers of the conductive metal was measured. 28 samples were measured for the protective element of the present disclosure, and 59 samples were measured for the protective element of the comparative example.

As a result of the measurement, the average value of the resistance values of the examples and the average value of the resistance values of the comparative examples were almost the same. On the other hand, the ratio of the standard deviation to each average value (standard deviation / average value) was 5.5% in the example sample and 12.0% in the comparative example sample. That is, it was confirmed that the protective element of the present disclosure has a small variation in resistance value.

-Blocking time For each of the examples and comparative examples, the blocking time was measured using 5 samples each. The test was performed with applied currents of 80 A and 60 A.

As a result of the measurement, the ratio of the standard deviation to the average value for the example sample was 7.8% at 80A and 4.5% at 60A. On the other hand, the ratio of the standard deviation to the average value for the comparative example sample was 17.1% at 80A and 33.9% at 60A. That is, it was confirmed that the protective element of the present disclosure has a small variation in breaking time.

The protective element of the present invention can be used as a protective element that cuts off the flow of an excessive current when an excessive current flows in an electric device such as a secondary battery.

1 ... Protective element 2 ... Layered element 3, 4 ... Conductive metal thin layer 5 ... Conductive connection part 6 ... Bridge part 7 ... First annular metal thin layer 8 ... Second annular metal thin layer 9 ... Through opening

Claims (8)

Layered elements formed of insulating resin and
It has a conductive metal thin layer provided on at least one of both main surfaces of the layered element.
The layered element is an annular shape having a through opening in the center.
The conductive metal thin layer provided on the main surface of one of the annular layered elements is a first annular metal thin layer located on the outer edge side of the annular layered element, that is, the annular layered element. It consists of a second annular metal thin layer located on the inner porch, and a fuse pattern that electrically connects them.
There are 2 to 8 fuse patterns at equal angles with respect to the center of the annulus.
The conductive metal thin layer and the fuse pattern are integrally formed.
An insulating layer is present on the thin metal layer having the fuse pattern so as to cover at least the fuse pattern.
Protective element. The layered element has at least one through opening and
The conductive metal thin layer is provided on both main surfaces of the layered element.
The conductive metal thin layers provided on both main surfaces of the layered element are electrically connected by a conductive connecting portion passing through the through opening.
The protective element according to claim 1. The protective element according to claim 1 or 2 , wherein the distance between the first annular metal thin layer and the second annular metal thin layer is 0.1 mm to 5.0 mm. The protective element according to any one of claims 1 to 3 , wherein the width of the first annular metal thin layer is larger than the width of the second annular metal thin layer. The protective element according to any one of claims 1 to 4 , wherein the conductive metal thin layer contains a nickel foil or a copper foil. An electric device comprising the protective element according to any one of claims 1 to 5. A sealing body comprising the protective element according to any one of claims 1 to 5. A secondary battery cell comprising the protective element according to any one of claims 1 to 5.

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