JP2000348583A - Alloy temperature fuse - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce resistance value of a welding interface, prevent self-heating, and appropriately actuate at a prescribed temperature by polishing and removing heterogeneous thin film of an electrode, welding a low melting point fusible alloy piece, and using a specific lead wire. SOLUTION: Opposite electrodes 2 are formed by baking conductive paste having metal grains as conductive components on an insulating plate such as ceramic, a belt nickel lead conductor 3 of identical quality with the can body of a secondary battery is connected to the respective electrodes, and a low- melting point fusible alloy piece 4 is welded between the both electrodes. In this case, the surface of the electrode 2 is polished to remove a heterogeneous thin film and welded, so that the temperature rise due to the high resistance value of the heterogeneous thin film can be eliminated. Then, the low melting point fusible alloy piece 4 is coated with flux 5 and seals the insulating plate 1 as covering thereover. The ratio of the metal grains occupied on the polished surfaces of the electrodes is set to 80% or more, the Vickers hardness and the thickness of the lead wire are set to 100-280 and 50-850 μm, and the rated current value is set to 0.1-15 A.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an alloy type temperature fuse, which is useful for preventing abnormal temperature rise of a lithium ion secondary battery or the like.

[0002]

2. Description of the Related Art In recent years, portable telephones, PHSs and portable parsers have been developed.
As a power source for portable electronic devices such as sonal computers,
A battery that can be repeatedly charged and discharged, that is, a secondary battery is used. As this secondary battery, a lithium ion secondary battery has been receiving attention because of its high energy density, long life cycle, high operating voltage, and the like. In this lithium ion secondary battery or the like, if energy is released at once for any reason, the battery may be exploded due to an abnormally high temperature. Therefore, the temperature fuse is closely attached to a can body of a lithium ion secondary battery or the like, and is mounted so as to be inserted in series between the positive electrode and the negative electrode of the battery, so that the battery reaches a predetermined upper limit temperature. It has been proposed to electrically shut off the battery circuit when it reaches.

One of the requirements for the temperature fuse for a secondary battery is that it is thin and small. As such a thin and small temperature fuse, an alloy type temperature fuse shown in FIG. 6 is known. is there. In the alloy type temperature fuse shown in FIG. 6A, opposed electrodes 2 ', 2' are provided on an insulating substrate such as a ceramic plate 1 'by printing and baking a conductive paste.
A lead conductor 3 'is joined to each electrode 2', and both electrodes 2 ',
A low-melting-point fusible alloy piece 4 'is connected between 2', a flux 5 'is applied to the low-melting-point fusible alloy piece 4', and the flux-coated low-melting-point fusible alloy piece is sealed with a resin layer 6 '. .

In the alloy type temperature fuse shown in FIG. 6B, the tips of a pair of strip-shaped lead conductors 3 ', 3' are thermally fused to the surface of a plastic base film 11 '. A low-melting-point fusible alloy piece 4 'is connected between the ends of the conductors, a flux 5' is applied to the low-melting-point fusible alloy piece 4 ', and the flux-coated low-melting-point fusible alloy piece is applied to the plastic cover film 12. 'Is sealed.

In the alloy type temperature fuse shown in FIG. 6 (c), the tips of a pair of strip-shaped lead conductors 3 ', 3' are watertight from the back surface of the plastic base film 11 'to the surface. Appeared and lead conductor 3 'and plastic base
And the exposed conductor 3
A low melting point fusible alloy piece 4 'is connected between 1' and 31 ', and a flux 5' is applied to this low melting point fusible alloy piece 4 '.
Flux coated low melting point fusible alloy piece is plastic cover
It is sealed with a film 12 '.

Further, another condition required for the temperature fuse for the secondary battery is that the lead conductor is made of the same material as the can so that the lead conductor can be easily welded to the can of the secondary battery. For example, nickel may be used. However, nickel is a metal which is difficult to be solder-bonded. In the alloy type temperature fuse shown in FIG. 6A, when the lead conductor 3 'is a nickel conductor, the lead conductor 3' and the conductive pad are used. Solder bonding with the strike-baked electrode 2 'becomes difficult. Further, in the alloy type temperature fuse shown in FIGS. 6B and 6C, it is difficult to weld one end of the low melting point fusible alloy at the tip of the nickel lead conductor.

Therefore, for the alloy type temperature fuse shown in FIG. 6A, the tip of the nickel lead conductor 3 'is tin-plated, and the tin-plated surface and the conductive paste baked electrode 2 are used. It has been proposed to join with. For the alloy type temperature fuses shown in FIGS. 6B and 6C, a copper conductor is provided on the surface of the tip of the nickel lead conductor by cladding of copper foil, copper plating or the like. It has been proposed to weld one end of a low-melting-point fusible alloy to this copper conductor (JP-A-11-40026).

[0008]

In the above-mentioned lithium ion secondary battery or the like, it is possible to set a high rated current because of its high energy density. However, according to the results of examination of the alloy type temperature fuse shown in FIG. 6A by the present inventors, a heterogeneous thin film (about 10 nm in thickness) generated by a reaction with an atmospheric gas at the time of baking exists on the electrode surface. Therefore, the welding interface between the conductive paste-baked electrode and the low melting point fusible alloy piece has a high resistance, and the occurrence of temperature fuse operation errors due to the heat generated by the normal current in this high resistance portion can be avoided. Absent. That is, assuming that the temperature rise of the low melting point fusible alloy piece based on the heat generated by the normal current is ΔT, the temperature (Tx−ΔT) lower than the above upper limit temperature (Tx)
Causes the alloy type temperature fuse to operate, which inevitably reduces the operating accuracy of the alloy type temperature fuse.

6 (b) and 6 (b) in which the leading end of the lead conductor is heated and fused to a plastic base film.
Also in the alloy type temperature fuse shown in (c), oxidation of the copper conductor surface at the tip of the lead conductor is promoted due to heating, and vaporized substances generated by heating from the plastic base film are attached. As a result, the resistance value of the welding interface between the copper conductor surface and the low melting point fusible alloy piece becomes higher. An operation error due to heat generation due to current is not negligible.

Therefore, in the thin and small alloy type temperature fuse shown in FIG. 6, the lead conductor is made of the same material as that of the can of the secondary battery, thereby facilitating welding attachment. Lithium cannot be obtained simply by providing an easily solderable conductor at the tip to facilitate solder joining between the lead conductor and the conductive paste baking electrode and welding between the lead conductor and the low melting point fusible alloy piece. Under a high rated current based on the high energy density of the ion secondary battery, it is difficult to guarantee proper prevention of abnormal heat generation of the secondary battery.

An object of the present invention is to provide an alloy type temperature fuse which can be suitably used for preventing abnormal temperature rise of a high energy density secondary battery such as a lithium ion secondary battery. More specifically, the lead conductor is made of the same material as that of the rechargeable battery can, so that it can be easily welded to the rechargeable battery and the rated current is set high according to the high energy density of the rechargeable battery. Another object of the present invention is to provide a thin and small alloy type temperature fuse which can be operated with high accuracy.

[0012]

According to one aspect of the present invention, there is provided an alloy-type temperature fuse comprising a conductive paste comprising metal particles as a conductive component.
A counter electrode is provided on the insulating substrate by baking the strike, a lead conductor is joined to each electrode, a low melting point fusible alloy piece is connected between both electrodes, and a flux is applied to the low melting point fusible alloy piece, A temperature fuse in which the flux-coated low-melting-point fusible alloy piece is sealed, the electrode surface is polished, the low-melting-point fusible alloy piece is welded to the polished surface, and the lead conductor is made of nickel. Wherein the flux-coated low-melting-point fusible alloy piece is sealed with a plastic film surrounding the insulating substrate, and the proportion of metal particles on the polished surface of the electrode is 80% or more. The nickel lead conductor is formed in a strip shape, the Vickers hardness is 100 to 280, the thickness is 50 to 850 μm, and the rated current value is 0.1 A to 15 A, preferably 1.
5A to 15A, a lead conductor is welded to a battery can, and used. Instead of a nickel lead conductor, any one of a stainless steel lead conductor, an aluminum lead conductor, and an iron lead conductor is used. It is possible to use

[0013] Another alloy type temperature fuse according to the present invention is:
The leading ends of the pair of strip-shaped lead conductors are exposed water-tightly from the back surface of the plastic base film to the surface, and the lead conductor and the plastic base film are fused to each other. Is a temperature fuse in which a low melting point fusible alloy piece is connected, a flux is applied to the low melting point fusible alloy piece, and the flux coated low melting point fusible alloy piece is sealed. The tip surface is a copper conductor or silver or gold conductor and a nickel conductor, and the copper, silver or gold conductor surface is polished and one end of a low melting point fusible alloy is welded to the polished surface. In another alloy type temperature fuse according to the present invention, the tips of a pair of strip-shaped lead conductors are fused to the surface of a plastic base film, and a low melting point is melted between the tips. The alloy flakes are connected, and the low melting point fusible alloy flakes Is a temperature fuse in which a flux-coated low melting point fusible alloy piece is sealed. Alternatively, the surface of the silver conductor is polished and one end of a low-melting-point fusible alloy is welded to the polished surface. In each case, the Vickers hardness of the nickel strip-shaped lead conductor is 100%. ~ 28
0, the thickness is 50 to 850 μm, the rated current value is 0.1 A to 15 A, preferably 1.5 A to 15 A, the strip-shaped lead conductor is welded to the battery can, and nickel is used. Instead of the strip-shaped lead conductor, any one of a stainless steel strip-shaped lead conductor, an aluminum strip-shaped lead conductor and an iron strip-shaped lead conductor can be used.

[0014]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1A is a drawing showing an example of an alloy-type temperature fuse according to the present invention, and FIG. 1B is a cross-sectional view taken along a line in FIG. In FIG. 1, reference numeral 1 denotes an insulating plate having heat resistance and good thermal conductivity, for example, a ceramic plate. Reference numerals 2, 2 denote burned electrodes of a conductive paste provided on the insulating plate 1, reference numerals 3, 3 denote nickel strip-shaped lead conductors connected to the electrodes 2, 2, and reference numeral 4, a low melting point connected between the electrodes 2, 2. A fusible alloy piece which is polished on the surface of each electrode 2 and then connected to each electrode 2 and a lead conductor 3;
The low melting point fusible alloy piece 4 is connected between the two. Reference numeral 5 denotes a flux applied on the low melting point fusible alloy piece 4, and 6 denotes a resin layer in which the flux applied low melting point fusible alloy piece is sealed.
A reinforcing plate having high mechanical strength can be fixed to the surface of the resin layer 6 to reduce the thickness of the entire sealing layer.

FIG. 2A is a drawing showing another example of the alloy type temperature fuse according to the present invention, and FIG. 2B is a drawing showing FIG.
FIG. In FIG. 2, reference numeral 1 denotes an insulating plate having heat resistance and good thermal conductivity, for example, a ceramic plate. Reference numerals 2, 2 denote burned electrodes of a conductive paste provided on the insulating plate 1, reference numerals 3, 3 denote nickel strip-shaped lead conductors connected to the electrodes 2, 2, and reference numeral 4, a low melting point connected between the electrodes 2, 2. After the surface of each electrode 2 is polished, the connection between each electrode 2 and the lead conductor 3 and the connection of the low melting point fusible alloy piece 4 between the electrodes 2 and 2 are performed. . 5 is a flux applied on the low melting point fusible alloy piece. 61 is a plastic film in which a flux-coated low melting point fusible alloy piece is sealed,
The periphery of the insulating substrate 1 is sealed with a heat seal or the like. Instead of using these plastic films,
It is also possible to insert a heat-shrinkable plastic tube through the insulating plate and heat-shrink it. Further, it is also possible to cover the flux-applied low-melting-point fusible alloy piece with a resin-applied layer and then perform final sealing with a plastic film or a heat-shrinkable plastic tube.

The welding of the end of the low melting point fusible alloy piece 4 to the electrode 2 is performed by a resistance welding method in which a pin electrode is brought into contact with a joint portion and an electrode portion separated from the joint portion, and a pulse current is applied to perform welding. A thermocompression method in which the joint is pressed with a heating pin, an ultrasonic heating method in which a horn chip is brought into contact with the joint, and the like can be used. The above-mentioned conductive paste is obtained by forming a mixture of a conductive metal powder (having a particle diameter of usually 0.4 to 6 μm), a glass powder and a metal oxide powder in a paste form with a solvent (for example, ethyl cellulose). used. For example, Ag-based paste using Ag, Ag-Pd, Ag-Pt as the conductive metal powder, Cu-based paste, Au-based paste, or the like can be used. The electrodes are provided by printing and baking a conductive paste on a ceramics plate. Baking is usually performed in an air atmosphere, but may be performed in an inert gas atmosphere such as nitrogen. The thickness of this electrode is 5 μm to 100 μm,
In the baking, a heterogeneous thin film having a high electrical resistance of several tens nm in thickness is formed on the surface of the electrode due to a reaction between the atmosphere gas and the surface of the printed conductive paste and a deposition of a decomposition product of the binder.

However, in the alloy type temperature fuse according to the present invention, the extraneous thin film is ground and removed (the polishing allowance is about 1 μm is sufficient), and the end of the low melting point fusible alloy piece is welded to the electrode. As a result, the resistance value of the welding interface between the low melting point fusible alloy piece and the electrode can be sufficiently reduced, and the interfacial welding strength can be increased by improving the weldability, stabilizing the cross-sectional area of the low melting point fusible alloy piece. Can be maintained. Therefore, the resistance value of the low melting point fusible alloy piece including the welded portion can be sufficiently reduced, and even if the rated current value is set to a large value, self-heating of the low melting point fusible alloy piece is prevented and the appropriate temperature is maintained at a predetermined temperature. Can work reliably. In addition, the double oxidation prevention mechanism of sealing with a resin layer and the like and flux application prevent late oxidation of the polished surface of the electrode well, so that wetting of the molten low melting point fusible alloy on the electrode surface can be prevented. When the temperature fuse is operated, the molten low melting point fusible alloy is well wetted by the electrode in the presence of the molten flux and can be quickly separated.

The electrode surface is preferably polished over the entire surface, but it is also possible to polish only the welded portion of the low melting point fusible alloy piece.

In the alloy type temperature fuse according to the present invention, the electrode and the nickel strip lead conductor are joined by resistance welding, laser welding, or the like. As a result, entrapment of foreign substances into the welded portion can be eliminated, and the connection between the electrode and the nickel strip lead conductor can be performed with a low resistance value and excellent mechanical strength.
Ratio α occupied by metal particles on the polished surface of the electrode
(If the area of the membrane electrode sample is S and the area occupied by the metal particles in the plane is S ′, α = S ′ / S × 100%
) Is 80% or more, preferably 9%, in order to increase the mechanical strength and electrical conductivity of the joint between the electrode and the low melting point fusible alloy piece and the joint between the electrode and the nickel lead conductor.
Desirably, it is 0% or more. The ratio α can be measured by observation with an electron microscope or by X-ray fluorescence analysis. For example, a membrane electrode sample having α of 80% is prepared, and when the surface of the membrane electrode sample is irradiated with white X, the metal particle Assuming that the intrinsic X-ray intensity of the metal is z, if the membrane electrode has an intrinsic X-ray intensity of z or more, it can be determined that the ratio of the metal particles on the surface of the membrane electrode is 80% or more.

It is desirable to use a nickel strip-shaped lead conductor having a Vickers hardness of 100 to 280, preferably 130 to 220, and a thickness of 50 to 300 μm, preferably 80 to 160 μm. Thus, Vickers hardness 1
Since it is not less than 00, sufficient rigidity can be imparted to the nickel strip-shaped lead conductor even at a thin thickness of 50 μm, and the lead is used for joining a low melting point fusible alloy piece or welding to equipment. Since the conductors can be stably held and welded easily, and the Vickers hardness is 280 or less, even if a relatively thick lead conductor having a thickness of 300 μm is bent by welding, the bent portion is formed at the bent portion. Can be easily welded by eliminating the occurrence of cracks. With such a Vickers hardness and thickness lead conductor, it is also possible to form a hole in the center of the end or cut out a part of the lead and weld it to equipment.

The alloy type temperature fuse according to the present invention can be suitably used for preventing abnormal heat generation of a secondary battery, particularly a lithium ion secondary battery. FIG. 3 shows an example of a use state of the alloy type temperature fuse shown in FIG. 2, and c shows a nickel can body which is a negative electrode insulated and separated at a portion b with respect to a positive electrode cap a. The insulating film i on the body c is locally peeled off,
The main body A of the alloy type temperature fuse and one nickel lead conductor 31 are brought into contact with the exposed can body surface, and the lead conductor 3
1 and the can c are joined by resistance welding or the like, and the positive terminal of the cap a and the other lead conductor 32 of the alloy type temperature fuse are electrically connected to the load of a portable device as two terminals. The welding of one of the lead conductors 31 to the can body b is easy because of the welding of nickel and the melting point of the low melting point fusible alloy piece as described above even when used at a large rated current. The battery can be operated at the exact temperature regulated by the temperature fuse, and because the temperature fuse is thin and small, the external dimensions of the battery fitted with the temperature fuse can be kept almost unchanged, and abnormal heat generation of the lithium ion secondary battery can be prevented. Suitable for prevention. In this use mode, when an abnormal current flows due to an internal short-circuit of the secondary battery or the like, the current is cut off by the heat generation and the melting of the low melting point fusible alloy piece due to the abnormal current, that is, as a current temperature fuse. Can also function.

The rated current is set to 0.1 A to 15 A. In this case, the low melting point fusible alloy piece has a resistance value of 45 mΩ.
Or less, preferably 15 mΩ or less, particularly preferably 2 mΩ.
The following are used, for polishing the electrode surface,
Under the cross-sectional dimensions of the low melting point fusible alloy piece (diameter for round wire, thickness for ribbon) 50 to 800 µm, the resistance value passing through the lead conductor and electrode and the low melting point fusible alloy piece should be sufficient. 20mΩ or less for the low melting point fusible alloy piece of 45mΩ or less, and 15m for the low melting point fusible alloy piece.
20 mΩ or less for Ω or less, and 12 mΩ or less for resistance value of low melting point fusible alloy piece of 2 mΩ or less), and self-heating of low melting point fusible alloy piece is well prevented to lower the alloy type temperature fuse. It can be operated at a precise temperature controlled by the melting point of the fusible alloy piece. Further, it is possible to further reduce the thickness of the alloy-type temperature fuse by setting the cross-sectional dimension (diameter in the case of a round wire, thickness in the case of a ribbon) of the low melting point fusible alloy piece to 350 μm or less.

The low melting point fusible alloy piece contains an alloy having a solidus temperature of 80 ° C. to 120 ° C. and a solidus temperature of 80 ° C. to 120 ° C., for example, 30 to 75% by weight of In and 5 to 50% by weight of Sn. , Cd 0.5 to 25% by weight, and an alloy in which one or more of Au, Ag, Cu, Al and Bi are added to the alloy composition in a total amount of 0.1 to 5% by weight, Bi4
8 to 53% by weight, Pb 28 to 33% by weight, Sn 13 to 1
9% by weight of alloy, In 0.5-4% by weight, Bi 50-5
An alloy of 4% by weight, 30 to 34% by weight of Pb, and 14 to 18% by weight of Sn can be used.

The flux applied to the low melting point fusible alloy piece promotes spheroidization and separation while maintaining the polished electrode surface in a non-oxidized state to promote the wetting of the molten low melting point fusible alloy piece to the electrode. Natural rosin, modified rosin (hydrogenated rosin, disproportionated rosin, polymerized rosin, etc.) and those obtained by adding a hydrochloride of diethylamine, a hydrobromide of diethylamine, etc. to these purified rosins can be used.

The insulating plate has a thickness of, for example, 100 μm
A ceramic plate such as an alumina ceramic plate or an aluminum nitride substrate of up to 1000 μm, a glass plate, a glass epoxy plate, a paper phenol plate and the like can be used. Further, a conductive paste is printed on an electrode pattern on an unfired ceramic sheet (green sheet), and the ceramic sheet and the conductive paste electrode pattern are heated at a time. It can also be fired.

The above-mentioned coating type sealing resin paints include:
A curable resin liquid having a viscosity of 50,000 to 600,000 cps can be used. For example, bisphenol-based epoxy resins obtained from bisphenol A and epichlorohydrin, novolak-type epoxy resins, alicyclic epoxy resins,
A curing agent (diamine, polyamine, polyamide, organic acid, vinylphenol, etc.) is mixed with an epoxy resin or the like in which an epoxy group is introduced by reacting polychloroalcohol with epichlorohydrin, and alumina, calcium carbonate, etc. And the like, to which a filler such as those described above can be added. In addition, a curable resin liquid containing an unsaturated polyester, diallyl phthalate resin, silicone, or polyurethane as a curable resin can also be used.

The plastic film has a thickness of 5 μm.
A thermoplastic resin film of m to 260 μm, preferably 160 μm to 210 μm can be used. For example, engineering plastics such as polyethylene terephthalate, polyamide, polyimide, polybutylene terephthalate, polyphenylene oxide, polyethylene sulfide, and polysulfone, holiacetal, polycarbonate,
Engineering plastics such as polyphenylene sulfide, polyoxybenzoyl, polyether terletone, polyetherimide, polyvinyl chloride, polyvinyl acetate, polymethyl methacrylate, polyvinylidene chloride, polytetrafluoroethylene, ethylene polytetrafluoroethylene Copolymer, ethylene vinyl acetate copolymer (EVA, AS resin, ABS resin, ionomer,
AAS resin, ACS resin, etc.).

In the above embodiment, nickel is used for the lead conductor. However, when the metal surface of the lead conductor to be welded and joined is stainless steel, aluminum or iron, a stainless steel lead conductor or aluminum lead is used. Lead conductors or iron lead conductors are used. Also in the case of these lead conductors, the lead conductors are stably held at the time of joining the low melting point fusible alloy pieces or at the time of welding and joining to equipment, so that they can be easily welded. The thickness is set so that even if the lead conductor is bent by welding, cracks are not generated at the bent portion and welding can be easily performed. For example, in the case of a stainless steel lead conductor, the thickness is set to 50 μm to 300 μm.

In any of the above embodiments, a resistor is mounted on the insulating plate, and an abnormality other than temperature is detected, for example, a voltage rise during overcharge of the secondary battery is detected, and the resistor is energized to generate heat. The melting of the fusible alloy pieces, that is, the operation of the temperature fuse at both abnormal temperature rise and other abnormalities, can be performed.

The alloy type temperature hue according to any of the above embodiments.
In order to manufacture a conductor, usually, after the burned electrode of the conductive paste is polished, the lead conductor is joined and the low melting point fusible alloy piece is welded. Then, a lead conductor may be bonded to the electrode, and thereafter, the electrode surface may be polished, and a low melting point fusible alloy piece may be welded to the polished surface.

FIG. 4 (A) is a drawing showing another example of the alloy type temperature fuse according to the present invention, and FIG. 4 (B) is a cross-sectional view of FIG. 4 (A). . In FIG. 4, 1
1 is a plastic base film. Reference numerals 3 and 3 denote nickel strip-shaped lead conductors, the tip of which is a copper conductor formed by cladding or copper plating of copper foil (including copper alloy foil), and the back of the tip is a plastic base film 11.
Is fused by a hot press. Reference numeral 4 denotes a low-melting-point fusible alloy piece in which the surface of the copper conductor at the tip of the lead conductor is polished and one end of the low-melting-point fusible alloy is welded to the polished copper conductor surface.
Reference numeral 5 denotes a flux applied to the low-melting-point fusible alloy piece, and 12 denotes a plastic cover film disposed on the surface of the plastic base film 11, between the films around the plastic cover film and between the plastic cover film and the strip. The space between the lead conductor and the lead conductor is sealed with a hot press, ultrasonic fusion, an adhesive or the like.

FIG. 5A shows a temperature hue according to the present invention.
FIG. 5 (b) is a cross-sectional view taken along the line (b) of FIG.
The leading ends of the conductors 3 and 3 are made of copper conductors by cladding or copper plating of copper foil (including copper alloy foil), and the leading ends are placed on the plastic base film 11 by hot pressing or the like from the back side to the front side. Then, the exposed portions (copper surfaces) 31, 31 at the tips of these strip-shaped lead conductors are polished, and a low melting point fusible alloy piece 4 is welded to the polished copper conductor surfaces. Then, the flux 5 is applied to the low melting point fusible alloy piece 4 and the flux applied low melting point fusible alloy piece is sealed with the plastic cover film 12.

In any of the above embodiments, the polishing range is a region that completely includes the portion where the low melting point fusible alloy piece is to be welded. Further, the tip portions of the nickel strip-shaped lead conductors 3 and 3 may be silver or gold conductors by silver plating or gold plating.

In the embodiment shown in FIGS. 4 and 5, the tip surface of the nickel lead conductor is made of a copper, silver or gold conductor which is more excellent in solderability than nickel, which is a material of the lead conductor. However, the tip of the plastic base
If an oxide film formed on the surface of the copper, silver or gold conductor by the heating at the time of fusing to the base film 11 or the attachment of the vaporized substance generated from the plastic base film by the heating are left, a good solder having a good angle is provided. Wearability will be impaired.

However, in the alloy type temperature fuse according to the present invention, the surface of the copper, silver or gold conductor is polished, and one end of the low melting point fusible alloy is welded to the polished surface. The resistance value of the weld interface of the molten alloy piece can be sufficiently reduced, the interfacial welding strength can be increased by improving the weldability, and the cross-sectional area of the low melting point fusible alloy piece can be stably maintained. Therefore, the resistance value of the low melting point fusible alloy piece including the welded portion can be sufficiently reduced, and even if the rated current value is set to a large value, self-heating of the low melting point fusible alloy piece is prevented and the appropriate temperature is maintained at a predetermined temperature. Can work reliably. In addition, due to the double oxidation prevention mechanism of sealing and flux application, the late oxidation of the polished surface of copper or silver or gold conductor can be well prevented, so that the molten low melting point fusible alloy copper or silver conductor surface Can be assured well, and when the temperature fuse is operated, the molten low melting point fusible alloy can wet the copper or silver or gold conductor surface in the coexistence with the molten flux and be quickly separated. Therefore, in the embodiment shown in FIGS. 4 and 5, even if the rated current value is set high, the self-heating of the low melting point fusible alloy piece is suppressed well, and the temperature is controlled by the melting point of the low melting point fusible alloy piece. It can be operated properly.

In these embodiments, the same low melting point fusible alloy pieces and fluxes as those in the above embodiments can be used. In the same manner as in the above embodiment, the nickel strip-shaped lead conductor has a Vickers hardness of 100 to 280 and a thickness of 50 to 8.
Preferably it is 50 μm. Further, similarly to the above embodiment, one of the lead conductors can be used by welding to the can body of the secondary battery, and when the metal surface to which the lead conductor is welded and joined is stainless steel, aluminum or iron, Stainless steel lead conductor,
An aluminum conductor or an iron lead conductor can be used. Also in the case of these lead conductors, the lead conductors are stably held at the time of joining the low melting point fusible alloy pieces or at the time of welding and joining to equipment, so that they can be easily welded. Lee
The thickness is set so that even if the lead conductor is bent by welding, cracks are not generated at the bent portion and welding can be easily performed. For example, in the case of a stainless steel lead conductor, 50 μm
３００300 μm. Further, the plastic film used in the above embodiment can be used as the plastic base film or the plastic cover film.

[0037]

Embodiment 1 An alloy-type temperature fuse having the structure shown in FIG. 1 was used. The conductive paste had a silver paste with a silver / binder weight ratio of 100/20. Granules having an average particle diameter of about 10 μm and binder particles having an average particle diameter of about 5 μm were used. This conductive paste was printed in the form of an electrode on an alumina ceramic plate having a thickness of 500 μm, a width of 5.0 mm, and a length of 80 mm using a screen mesh and a squeegee, and further dried at a temperature of 120 ° C. for 15 minutes. Next, firing is performed at a peak temperature of 850 ° C. for 10 minutes and a cycle of 60 minutes, the electrode surface is polished with a grinding wheel, and a nickel strip lead conductor is joined to each electrode by resistance welding. A low melting point fusible alloy wire having a diameter of 0.5 mm and a eutectic point temperature of 94 ° C. was welded. The resistance value between the electrodes after welding the low melting point fusible alloy wire was 2 mΩ. Further, a flux was applied to the low melting point soluble alloy wire and sealed with an epoxy resin to obtain an alloy mold temperature fuse according to the present invention. This alloy type temperature fuse (number of samples 2
0), immersed in an oil bath while applying a current of 2 A, and heated the oil at a heating rate of 1 ° C./min.
The fusing operation was performed at 3 ° C. (average value of 20 pieces).

Comparative Example 1 The procedure was the same as in Example 1 except that the polishing of the electrode surface was omitted. When a fusing test was conducted under a current of 2 A in the same manner as in Example 1, the oil temperature was 91.5 ° C.
(Average value of 20 pieces). The fusing operation temperature was 1.5 ° C. lower than that in Example 1, and an operation error due to self-heating of the low melting point fusible alloy wire was observed.

[Embodiment 2] A belt-shaped lead conductor having the structure shown in FIG. 5 was formed by using a polyethylene terephthalate film having a thickness of 150 μm and a plane size of 5 mm × 11 mm for a plastic base film and a plastic cover film. Has a thickness of 100 μm and a Vickers hardness of 190 (Vickers hardness is an alloy type temperature fuse MV-2 manufactured by Shimadzu Corporation).
000), a nickel strip having a width of 3.5 mm and a length of 13 mm, which was clad with a copper foil at the tip. The leading end of the lead conductor is exposed to the plastic base film from the back surface to the front surface by a heating press, and the exposed copper foil surface is polished with a grinding wheel, then has a diameter of 0.3 mm and a eutectic point temperature of 94 ° C. Was welded. The resistance value between the exposed copper foil surfaces after welding the low melting point fusible alloy wire was 10 mΩ. Further, a flux was applied to the low melting point soluble alloy wire, and the periphery of the plastic cover film was sealed with a heat seal to obtain an alloy-type temperature fuse according to the present invention. The alloy type temperature fuse (20 samples) was immersed in an oil bath while applying a current of 3 A.
When the oil was heated at a heating rate of 0.5 ° C./min, the fusing operation was performed at an oil temperature of 93.4 ° C. (average value of 20 oils).

Comparative Example 2 The same operation as in Example 2 was carried out except that the polishing of the exposed copper foil surface was omitted. When a fusing test was conducted under the condition of 2 energization in the same manner as in Example 2, the oil temperature was 91.1.
The fusing operation was performed at ℃ (average value of 20 pieces). The fusing operation temperature was 2.3 ° C. lower than that in Example 1, and an operation error due to self-heating of the low melting point fusible alloy wire was recognized.

[0041]

The alloy type temperature fuse according to the present invention is used as a protector for preventing abnormal rise in temperature of a secondary battery, especially a lithium ion secondary battery, and has a thin and small size. Not only is the conductor made of a material with excellent weldability to the battery can, but it is also possible to prevent abnormal temperature rise of the above secondary battery even at a high rated current that meets the high energy density of the secondary battery. This is extremely useful for preventing abnormal temperature rise of a secondary battery, particularly a lithium ion secondary battery.

[Brief description of the drawings]

FIG. 1 is a view showing an embodiment of an alloy-type temperature fuse according to the present invention.

FIG. 2 is a view showing another embodiment of the alloy type temperature fuse according to the present invention.

FIG. 3 is a view showing an example of a use state of the alloy-type temperature fuse shown in FIG. 2;

FIG. 4 is a view showing another embodiment of the alloy type temperature fuse according to the present invention.

FIG. 5 is a view showing another embodiment of the alloy type temperature fuse according to the present invention.

FIG. 6 is a drawing showing a different conventional example.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Insulating plate 11 Plastic base film 2 Conductive paste baking electrode 3 Nickel lead conductor 4 Low melting point fusible alloy piece 5 Flux 6 Resin layer 12 Plastic cover film

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Toshiro Kawanishi 1-11-28 Shimanouchi, Chuo-ku, Osaka-shi Uchibashi S-Tech Co., Ltd. F-term (reference) 5G502 AA02 BA03 BB10 BB13 BC02 BC08 CC01 FF08 5H022 AA09 BB11 CC09 CC12 EE03 EE04 KK01

Claims (14)

[Claims] 1. An electrode having a counter electrode formed by baking a conductive paste containing metal particles as a conductive component, a lead conductor is joined to each electrode, and a low melting point fusible alloy is provided between both electrodes. Is a temperature fuse in which the flux is applied to the low melting point fusible alloy piece and the flux coated low melting point fusible alloy piece is sealed.The electrode surface is polished and the polished surface has a low melting point. An alloy-type temperature fuse, wherein one end of a molten alloy is welded and a lead conductor is a nickel conductor. 2. An opposite electrode is provided on an insulating substrate by baking a conductive paste containing metal particles as a conductive component, a lead conductor is joined to each electrode, and a low melting point fusible alloy is provided between both electrodes. Is a temperature fuse in which the flux is applied to the low melting point fusible alloy piece and the flux coated low melting point fusible alloy piece is sealed.The electrode surface is polished and the polished surface has a low melting point. An alloy-type temperature hue characterized in that one end of a molten alloy is welded and a lead conductor is a nickel conductor.
Z. 3. The alloy-type temperature fuse according to claim 2, wherein the sealing of the flux-coated low-melting-point fusible alloy piece is performed by a plastic film surrounding the insulating substrate. 4. The alloy-type temperature fuse according to claim 1, wherein the proportion of the metal particles on the polished surface of the electrode is 80% or more. 5. The nickel lead conductor is in the form of a strip, and has a Vickers hardness of 100 to 280 and a thickness of 50 to 850 μm.
5. The alloy mold temperature hue according to claim 1, wherein
Z. 6. The alloy type temperature fuse according to claim 1, wherein the rated current value is 0.1 A to 15 A. 7. An alloy-type temperature fuse according to claim 1, wherein the lead conductor is welded to a battery can. 8. The alloy type temperature hue according to claim 1, wherein any one of a stainless steel lead conductor, an aluminum lead conductor and an iron lead conductor is used in place of the nickel lead conductor. Z. 9. The front ends of a pair of strip-shaped lead conductors are exposed from the back surface of the plastic base film to the front surface in a watertight manner.
And the lead conductor and the plastic base film are fused, a low melting point fusible alloy piece is connected between the exposed conductors,
This is a temperature fuse in which flux is applied to the low melting point fusible alloy piece and the flux coated low melting point fusible alloy piece is sealed. Characterized in that the surface of the copper, silver or gold conductor is polished and one end of a low melting point fusible alloy is welded to the polished surface.
Z. 10. A tip of a pair of strip-shaped lead conductors is fused to the surface of a plastic base film, and a low melting point fusible alloy piece is connected between the tip ends. A temperature fuse in which a flux is applied and the flux-applied low-melting-point fusible alloy piece is sealed, and the strip-shaped lead conductor is a nickel conductor having a distal end surface made of copper or silver or gold conductor; An alloy-type temperature fuse characterized in that the surface of the copper, silver or gold conductor is polished and one end of a low melting point fusible alloy is welded to the polished surface. 11. The alloy-type temperature fuse according to claim 9, wherein the nickel strip-shaped lead conductor has a Vickers hardness of 100 to 280 and a thickness of 50 to 850 μm. 12. The alloy-type temperature fuse according to claim 9, wherein a rated current value is 0.1 A to 15 A. 13. An alloy-type temperature fuse according to claim 9, wherein the strip-shaped lead conductor is welded to a battery can. 14. A stainless steel strip lead, an aluminum strip lead, or an iron strip lead is used in place of the nickel strip lead.
The alloy type temperature fuse according to any of the above.