JP2000090792A - Alloy type thermal fuse - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an alloy type thermal fuse excellently usable for a micro- miniaturized and extremely thin thermal fuse having an actuating temperature of 80-120 deg.C such as a thermal fuse for a battery. SOLUTION: This thermal fuse has a resin base film 11 and a strip lead conductor 2, and the tip part of each strip lead conductor 2, 2 is adhered to the one side of the resin base film 11 by heat pressing, ultrasonic fusing or an adhesive. A fuse element 3 connected between the strip lead conductors 2, 2 by welding has an alloy composition containing 30-75 wt.% of In, 5-50 wt.% of Sn and 0.5-25 wt.% of Cd, preferably 40-60 wt.% of In, 25-50 wt.% of Sn and 10-15 wt.% of Cd, or more preferably 40-55 wt.% of In, 30-46 wt.% of Sn and 14-15 wt.% of Cd. This fuse has flux 4 applied on the fuse element and a resin cover film 12 placed on the surface of the resin base film 11, and a space between the films around the resin cover film and a space between the resin cover film and the strip lead conductor are sealed by ultrasonic fusing or an adhesive.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ultra-thin and ultra-compact alloy-type temperature fuse, for example, an alloy-type temperature fuse useful for preventing temperature rise of batteries such as lithium ion secondary batteries. .

[0002]

2. Description of the Related Art In an alloy type temperature fuse, a fuse element of a low melting point fusible alloy is blown off by heat generated due to an overcurrent of the device to cut off the power supply to the device, thereby causing abnormal heat generation of the device and a fire. Is prevented beforehand. A conventional alloy-type temperature fuse can be roughly classified according to the type of the fuse. A fuse element is connected between lead conductors arranged in a straight line, and the fuse is connected to the fuse element.
A cylindrical axial type in which a flux is applied to the fuse element, an insulating cylinder is inserted on the flux-applied fuse element, and the gap between each end of the insulating cylinder and each lead conductor is sealed with a sealing material; A fuse element is connected between the ends of the parallel lead conductors, a flux is applied to the fuse element, and a cap-type insulating case cylinder is placed on the flux-coated fuse element. −Single opening and parallel release−
A case type radial type in which the space between the lead element and the parallel lead conductor is sealed with a sealing material, a fuse element is connected between the tips of the parallel lead conductors, and a flux is applied to the fuse element;
A direct sealing radial type in which the flux-coated fuse element is directly surrounded by a sealing material, a pair of membrane electrodes are provided on an insulating substrate, and a lead conductor is connected to each membrane electrode, and a fuse is provided between these membrane electrodes. The fuse element is connected, a flux is applied to the fuse element, and the fuse element can be divided into a substrate type and the like in which a sealing material is coated so as to cover the fuse element.

Conventionally, a fuse element of an alloy type temperature fuse having an operating temperature of 80 to 120 ° C. has a melting characteristic adjusted to the operating temperature by adding Bi, Pb, or the like.
-Pb-Bi-based alloys and Sn-Pb-Bi-In-based alloys are used.

[0004]

In recent years, portable telephones and notebooks have been developed.
With the miniaturization and thinning of personal use electronic devices such as notebook personal computers and video cameras, secondary batteries (lithium-ion batteries, nickel-metal hydride batteries, etc.) as their power sources have been miniaturized. Ultra-small and ultra-thin alloy-type temperature fuses used for preventing temperature rise are also required. That is, in a lithium ion secondary battery or the like, since the energy density is high and a considerably large current flows during discharging or charging, there is a possibility that the temperature will rise. It has been considered that the fuse element is melted at a predetermined temperature rise (80 to 120 ° C.) to cut off the current supply. However, the dimensions of the alloy type temperature fuse are as follows. 1 mm or less in thickness, 5 m in plane dimension of main body (portion not including lead wire)
m × 12 mm or less is required. The operating temperature required for the battery temperature fuse is 80 to 120 ° C,
The melting characteristics of the alloy for a fuse element that can satisfy this operating temperature are in the range of liquidus temperature of 80 to 120 ° C and in the range of solidus temperature of 80 to 120 ° C.

A typical alloy type temperature fuse element alloy having such melting characteristics is, for example, Sn16.
However, if the fuse element of the ultra-thin and ultra-small battery temperature fuse is formed of this alloy, the unit length of the fuse element is known. The resistance value per unit becomes high and the temperature
Malfunction is likely to occur.

That is, the fuse element is heated due to Joule heat due to the load current, and the temperature is reduced by Δ
Assuming that T and the melting point of the fuse element are T and normal temperature is T ₀ , the temperature fuse is activated when the battery temperature rises by (T−ΔT−T ₀ ). Since the temperature fuse operates even if the temperature of the battery rises within a safe range, it is necessary to keep the above ΔT within a predetermined limit (usually within 10 ° C.). However, when a conventional fuse element alloy that satisfies the operating temperature of the battery temperature fuse of 80 to 120 ° C. from the viewpoint of melting characteristics is used as the fuse element of the battery temperature fuse,
It is difficult to keep ΔT within a predetermined limit (usually within 10 ° C.), and it is difficult to guarantee satisfactory operating characteristics.

[0007] It is an object of the present invention to operate at an operating temperature of 80-120.
It is an object of the present invention to provide an alloy type temperature fuse that can guarantee good operability even when used in a temperature fuse of a very small and ultra-thin temperature of, for example, a battery temperature fuse.

[0008]

According to the present invention, there is provided an alloy type temperature fuse having an alloy composition of In30.
~ 75 wt%, Sn5 ~ 50 wt%, Cd0.5 ~ 25
Wt%, preferably 40-60 wt% In, Sn25-
50% by weight, 10 to 15% by weight of Cd, particularly preferably Id
n 40 to 55% by weight, Sn 30 to 46% by weight, Cd14
-15% by weight, and one or two of Au, Ag, Cu, and Al in the alloy composition.
More than 0.1% by weight of seeds can be added.
Further, the sectional area of the fuse element is set to 0.03 to 0.1.
The thickness of 3 mm ² can be suitably used to prevent the temperature of the battery from rising.

[0009]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1A shows an example of a temperature fuse according to the present invention. In FIG. 1A, reference numeral 11 denotes a resin base film, and reference numeral 2 denotes a strip-shaped lead conductor. As shown in FIG. The portion is fixed to one surface of the resin base film 11 by hot pressing, ultrasonic fusion, an adhesive or the like. In FIG. 1A, reference numeral 3 denotes a strip-shaped lead conductor 2, 2.
A fuse element connected by welding between
n 30 to 75% by weight, Sn 5 to 50% by weight, Cd 0.5
-25% by weight, preferably 40-60% by weight of In, Sn
25 to 50% by weight, Cd 10 to 15% by weight, particularly preferably In 40 to 55% by weight, Sn 30 to 46% by weight, C
d is an alloy composition of 14 to 15% by weight.
The flux 12 applied to the closing element is a resin cover film disposed on the surface of the resin base film 11, and is provided between the films around the resin cover film and between the resin cover film and the strip-shaped lead conductor. The space is sealed with a hot press, ultrasonic fusion, an adhesive or the like.

The alloy composition of the fuse element 3 is as follows:
The operating temperature of the temperature fuse is set to 80 to 120 ° C., and the cross-sectional area of the fuse element is set to 0.03 to 0.13 mm ² to make the temperature fuse ultra-thin and ultra-compact. However, it meets the requirement of low specific resistance which can substantially eliminate Joule heat under load current, and has a solidus temperature of 80 to 120 ° C and a liquidus temperature of 80 to 120 ° C.
° C., the specific resistance is (10 to 30 μΩcm).

In order to further reduce the specific resistance, one or more of Au, Ag, Cu and Al can be added to the alloy composition in a total amount of 0.1 to 5% by weight.

According to the alloy type temperature fuse according to the present invention, the cross-sectional area of the fuse element is set to 0.03 to 0.13, as is clear from the comparison between the embodiment and the comparative example described later.
Even when the fuse element is made as small as ² mm, the heat generation of the fuse element due to the load current can be substantially eliminated. When the width of the fuse element is set to 1.4 mm, the thickness of the fuse element is set to 0.02 mm to 0.93 mm. The fuse element can be made very thin, and the portion occupied by the fuse element in the thickness of the temperature fuse body (1 mm or less) can be kept very small. (On the other hand, if a conventional fuse element alloy is used, The fuse element needs to have a cross-sectional area of 0.2 to 0.23 mm ² , and the thickness of the fuse element is set to the temperature fuse.
The portion occupied by the fuse element in the thickness of the fuse body (1 mm or less) is about 20%). Further, in the temperature fuse according to the present invention, since the volume of the fuse element is small, the molten alloy can be quickly separated by wetting of the electrode with the electrode, and the distance between the divided parts is necessary for insulation break. Since the distance (arc blocking distance) can be quickly reached, a quick breaking operation can be guaranteed. Therefore, according to the present invention, the operating temperature is 80-120 ℃ ultra-thin and ultra-small for batteries,
An alloy-type temperature fuse having excellent operability can be provided.

For example, a copper wire,
Rolled products such as aluminum wire, nickel wire, copper-plated iron wire, etc., and those obtained by applying tin plating to this rolled product can be used.
The thickness is usually 50 μm to 200 μm, preferably 100 μm
m and the width are usually 2 to 5 mm, preferably 3 mm.

The resin base film 11 and the resin cover film 12 are made of, for example, polyethylene terephthalate.
Engineering plastics such as polystyrene, polyamide, polyimide, polybutylene terephthalate, polyphenylene oxide, polyethylene sulfide, and polysulfone can be used. It is. The thickness of these individual films is usually 50-400 μm,
Preferably, it is 188 μm.

FIG. 2A shows a temperature hue according to the present invention.
FIG. 2B shows another example of a pair of band-shaped leads.
The front ends of the lead conductors 2 and 2 are exposed and fixed to the resin base film 11 from the back side to the front side by a hot press or the like, and then these fixed strip-shaped lead conductors 2 and 2 are exposed. The fuse element 3 is joined between the parts by resistance welding or the like, and the other configuration is substantially the same as that shown in FIG. 2, the same reference numerals as those in FIG. 1 indicate the same components.

FIG. 3A shows a temperature hue according to the present invention.
As shown in FIG. 3B, the tip of one of the strip-shaped lead conductors 21 is exposed to the resin base film 11 from the back side to the front side by hot pressing or the like. Let it stick,
The other end of the strip-shaped lead conductor 2 is fixed to the surface of the resin base film 11 by a hot press or the like.
In the above, a fuse is provided between the tip ends of both strip-shaped lead conductors 2 and 21.
The fuse element 3 is joined by resistance welding or the like, and a flux 4 is applied on the fuse element 3. Then, a resin cover film 12 is disposed on one side of the resin base film 11. 12 and the resin base film 11, and between the molded resin cover film 12 and the other strip-shaped lead conductor 2 are sealed by heat sealing, ultrasonic fusion or laser irradiation. It has stopped.

The thin temperature fuse according to the present invention can be used, for example, to protect a lithium ion secondary battery from abnormal heat generation.

FIG. 4 shows a lithium ion secondary battery, in which a spiral wound fuse element of a positive electrode 52 and a negative electrode 53 with a separator 51 interposed is accommodated in a negative electrode can 54, and the negative electrode 53 and the negative electrode can 54 is electrically connected to the bottom surface of the positive electrode 52, and a positive electrode collecting electrode 55
Is electrically connected to the collector electrode 55, and the upper end 541 of the negative electrode can 54 is caulked to the outer peripheral end of the outer side 56 of the explosion-proof valve plate and the outer peripheral end of the positive electrode cover 57 via the packing 58, and the explosion-proof The central concave portion of 56 is electrically connected to the positive electrode collecting electrode 59.

In order to attach the temperature fuse according to the present invention to the battery, one of the band-shaped lead conductors and the temperature-fused body are brought into close contact with the negative electrode can of the battery, and the other of the band-shaped lead conductors. And the negative electrode can is electrically connected, and the other strip-shaped lead conductor is insulated from the negative electrode can by separating or interposing an insulating film, and can be inserted in series into the battery.

A temperature fuse is disposed in a space between the explosion-proof valve plate 56 and the positive electrode cover 57 of the lithium ion secondary battery,
An insulating spacer r is interposed between the outer peripheral end of the explosion-proof valve plate 56 and the outer peripheral end of the positive electrode cover 57, and one of the strip-shaped lead conductors 2 is insulated from the outer peripheral end of the explosion-proof valve plate 56 by the insulating space. Alternatively, the other strip-shaped lead conductor 2 may be sandwiched between the outer peripheral end of the positive electrode cover 57 and the insulating spacer r and incorporated in the battery in series.

FIGS. 5 (a) and 5 (b) (a cross-sectional view taken along a line in FIG. 5 (a)) show another embodiment of the temperature fuse according to the present invention. ing. 5, the alloy type thermal fuse - figure frame - indicates the beam, strip Li inner periphery to one of the annular portion 201 shown in (a) 6 - and foil electrode f ₁ of one with de conductor 21 the resin space of annular shown in (b) of FIG. 6 - and foil electrode f ₂ having a de conductor 2 - and support the film s, strip Li inner periphery to the other of the annular portion 200 shown in (c) of FIG. 6 Are superposed with the lead portions 2 and 21 staggered by 180 °, and the interface between the foil electrodes f ₁ and f ₂ and the resin spacer film s can be bonded by heat fusion or the like.

In FIG. 5, A is a temperature fuse body disposed in the central space of the frame alloy type temperature fuse, and one end of one strip-shaped lead conductor 21 is attached to a resin base film 11. And the other end of the strip-shaped lead conductor 2 is fixed to the other surface of the resin-based film 11 and is locally exposed from one surface of the film 11 to the other surface. The fuse element 3 is connected by welding or the like between the portion and the tip end of one of the strip-shaped lead conductors 21 which is locally exposed, and a flux 4 is applied to the fuse element 3. A resin cover film 12 is disposed on the fuse-coated fuse element, and is disposed between the resin base film 11 and the resin cover film 12 around the resin cover film 12 and between the resin cover film 12 and the other strip-shaped resin. Between the lead conductor 2 and Sheet - le or ultrasonic welding or Le -
Sealed by irradiation.

In order to incorporate this temperature fuse into the battery shown in FIG. 4, the temperature fuse is sandwiched between the outer peripheral end of the explosion-proof valve plate 56 and the outer peripheral end of the positive electrode cover 57 without the interposition of the insulating spacer r. to explosion-proof valve plate 56 and the frame - arm alloy type thermal fuse - electrical contact between foil electrodes f ₁ of's → foil electrodes f ₁ of the Li - de conductor 21 → fuse -'s element 3 → foil electrodes f ₀ lead conductor 2 → frame alloy type temperature fuse foil electrode f ₀ and the positive electrode cover 57 make it possible to electrically connect the temperature fuse in series to the battery. it can.

[0022]

EXAMPLES Example 1 The alloy composition of the fuse element was as shown in Table 1 in which 40% by weight of In-46% by weight of Sn-
Cd was 14% by weight. The specific resistance of this alloy composition is 16μ
Ωcm. The structure of the temperature fuse used was as shown in FIG. 1, the length between the lead conductors of the fuse element was 2.5 mm, and the width (W) of the fuse element was 1.4 m.
m and the cross-sectional area (S) of the fuse element so that the resistance value of the fuse element at 2.5 mm is 6 mΩ so as to substantially eliminate Joule heat at a rated current of 2 A. Was set to 0.067 mm ² . Therefore,
The thickness (t) of the element is S / W = 0.048 mm
It is.

Example 2 The alloy composition of the fuse element was as shown in Table 1 in which 55% by weight of In and 30% by weight of Sn were used.
-Cd was 15% by weight. The specific resistance of this alloy composition is 13
μΩcm. As in Example 1, the fuse element had a cross-sectional area (S) of 0.054 mm ² so that the resistance of the fuse element was 6 mΩ. Therefore, the thickness (t) of the fuse element is S / W = 0.039 mm.

Example 3 As shown in Table 1, the alloy composition of the fuse element was In 44% by weight-Sn 42% by weight.
-Cd was 14% by weight. The specific resistance of this alloy composition is 16
μΩcm. The cross-sectional area (S) of the fuse element was set to 0.067 mm ² so that the resistance value of the fuse element was 6 mΩ as in the first embodiment. Therefore, the thickness (t) of the fuse element is S / W = 0.048 mm.

Example 4 The alloy composition of the fuse element was as shown in Table 1 in which 44% by weight of In-41% by weight of Sn.
-Cd 14% by weight-Ag 1% by weight. The specific resistance of this alloy composition is 15 μΩcm. In the same manner as in the first embodiment,
The fuse element had a cross-sectional area (S) of 0.063 mm ² so that the resistance value of the fuse element was 6 mΩ. Therefore, the thickness (t) of the fuse element is S / W =
0.045 mm.

Example 5 As shown in Table 1, the alloy composition of the fuse element was In 43.5 wt% -Sn 41 wt% -Cd 14 wt% -Cu 0.5 wt%. The specific resistance of this alloy composition is 16 μΩcm. The cross-sectional area (S) of the fuse element was set to 0.067 mm ² so that the resistance value of the fuse element was 6 mΩ as in the first embodiment. Therefore, the thickness (t) of the fuse element is S
/W=0.048 mm.

Comparative Example 1 As shown in Table 1, the alloy composition of the fuse element was as follows: Sn 16% by weight-Bi 52% by weight.
-Pb was 32% by weight. The specific resistance of this alloy composition is 50
μΩcm. As in Example 1, the fuse element had a cross-sectional area (S) of 0.208 mm ² so that the resistance of the fuse element was 6 mΩ. Therefore, the thickness (t) of the fuse element is S / W = 0.149 mm.

Comparative Example 2 As shown in Table 1, the alloy composition of the fuse element was 1% by weight of In—15.3% by weight of Sn—52% by weight of Bi—31.7% by weight of Pb. The specific resistance of this alloy composition is 49 μΩcm. As in Example 1, the fuse element had a cross-sectional area (S) of 0.204 mm ² so that the resistance of the fuse element was 6 mΩ. Therefore, the thickness (t) of the fuse element is S
/W=0.146 mm.

Comparative Example 3 As shown in Table 1, the alloy composition of the fuse element was 1% by weight of In—1.5% by weight of Sn.
-Cd 8% by weight-Bi 50.5% by weight-Pb 39% by weight
And The specific resistance of this alloy composition is 55 μΩcm. As in the first embodiment, the fuse element has a sectional area (S) of 0.2 so that the resistance value of the fuse element is 6 mΩ.
29 mm ² . Therefore, the thickness (t) of the fuse element is S / W = 0.164 mm.

Each of these examples and comparative examples (the number of each sample was 25) was immersed in an oil bath.
The operating temperature of the temperature fuse was measured by raising the oil temperature at a rate of ° C./min.

[0031]

[Table 1]

As is apparent from Table 1, both the working example and the comparative example can be used as a temperature fuse having an operating temperature of 80 to 120 ° C. However, the thickness of the fuse element in the working example is significantly smaller than that in the comparative example. Yes, base film, cover
When the fuse element has a thickness of about 39 to 48 μm with respect to the preferred thickness of the film and the strip-shaped lead conductor of 100 μm, the total thickness of the base film, the cover film and the strip-shaped lead conductor substantially exceeds the total thickness. A thin alloy type temperature fuse can be provided. However, in the comparative example, the thickness of the fuse element is almost equal to the thickness of each of the base film, the cover film and the strip-shaped lead conductor, and it is difficult to provide an ultra-thin alloy type temperature fuse. .

[0033]

The temperature fuse according to the present invention has a small thickness by reducing the cross-sectional area of the fuse element while ensuring good operability in an alloy type temperature fuse having an operating temperature of 80 to 120 ° C. It is possible to provide an ultra-thin and ultra-compact alloy-type temperature fuse as a temperature fuse for preventing a temperature rise of a secondary battery.

[Brief description of the drawings]

FIG. 1 is a drawing showing an example of a temperature fuse according to the present invention.

FIG. 2 is a drawing showing a different example of the temperature fuse according to the present invention from the above.

FIG. 3 is a drawing showing another example of the temperature fuse according to the present invention.

FIG. 4 is a view showing an example of a use state of the temperature fuse according to the present invention.

FIG. 5 is a drawing showing another example of the temperature fuse according to the present invention.

FIG. 6 is a view showing a frame used for the temperature fuse shown in FIG. 5;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 11 Resin base film 12 Resin cover film 2 Strip-shaped lead conductor 21 Strip-shaped lead conductor 3 Fuse element 4 Flux

Claims (5)

[Claims] An alloy composition of a fuse element is In30.
~ 75 wt%, Sn5 ~ 50 wt%, Cd0.5 ~ 25
An alloy-type temperature fuse characterized in that the weight is%. 2. The alloy composition of the fuse element is In40.
-60% by weight, Sn 25-50% by weight, Cd10-15
2. The alloy-type temperature fuse according to claim 1, wherein the temperature is set to% by weight. 3. The alloy type temperature fuse according to claim 1, wherein one or more of Au, Ag, Cu, and Al are added to the alloy composition in a total amount of 0.1 to 5% by weight. 4. The fuse element has a sectional area of 0.03 to 0.03.
0.13 mm ² and a claims 1 to 3 or according alloy type thermal fuse -'s. 5. The alloy type temperature fuse according to claim 1, which is used for preventing temperature rise of the battery.