JPH11144583A - Alloy type thermal fuse and manufacture of alloy type thermal fuse - Google Patents

Abstract

PROBLEM TO BE SOLVED: To connect a plate electrode and a low melting point fusible alloy foil by welding and secure safety electrical contact between them in the manufacture of a very thin alloy type thermal fuse. SOLUTION: In the manufacturing method of a thermal fuse in which a low melting point fusible alloy foil 4 is arranged between plate electrodes 2, 2 having larger thermal capacity than that of the metal foil 4, auxiliary pieces 5 having smaller thermal capacity than the thermal capacity of the plate electrode 2 are welded to both ends of the low melting point fusible alloy foil 4, then each auxiliary piece 5 is welded to each plate electrode 2.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ultra-thin alloy type temperature fuse and a method of manufacturing the same.

[0002]

2. Description of the Related Art In an alloy type temperature fuse, a fuse is used.
A low-melting-point fusible alloy piece is used as a cooling element, and power is cut off from the low-melting-point fusible alloy piece due to abnormal heat generation of the equipment to cut off power supply to the equipment to protect the equipment. In recent years, with the miniaturization of devices, thinner temperature fuses have been required. For example, in a lithium ion secondary battery, it has been proposed that a flat temperature fuse is sandwiched between the end of a positive electrode lid fixed by caulking through a gasket at the upper end of a negative electrode can and the end of a safety valve plate. However, the thickness required for the flat temperature fuse is an ultrathin thickness of 1 mm or less in terms of the size of the battery.

FIG. 5 shows an example of the above-mentioned flat type temperature fuse. Plate electrodes 2 'and 2' are provided above and below an insulating spacer 1 'having a central hole 11'. A low melting point fusible alloy piece 4 'as a fuse element is connected between the electrodes 2', 2 '. This flat temperature hue
It is effective to make the low-melting-point fusible alloy piece into a foil shape in order to reduce the thickness of the alloy. For example, a circular section having a diameter of 700 μm has the same sectional area as a section of a foil having a thickness of 100 μm and a width of 4000 μm. By adopting such a foil shape, the thickness of the low melting point fusible alloy piece can be reduced to 1/7, and the temperature hue can be reduced. It is effective to make a low melting point fusible alloy piece into a foil for an ultra-thin alloy.

[0003]

In the alloy type temperature fuse incorporated in the above-mentioned battery, even under normal conditions, thermal stress is applied due to, for example, daily or seasonal temperature changes. In order to ensure stable electrical contact between the plate and the plate electrode, it is necessary to weld the contact point. However, when welding the low melting point fusible alloy foil and the plate electrode by contact of the heating block, the heat capacity of the low melting point fusible alloy foil is smaller than the heat capacity of the plate electrode. The temperature of the fusible alloy foil rises faster and the fusible alloy foil with a low melting point melts out before the temperature at which the plate electrode can be welded, making welding very difficult. In contrast,
Instantaneous welding, for example, spot resistance welding or laser welding, is spot-like instant heating, so there is no problem due to the heat capacity.However, the low melting point fusible alloy foil is strong due to its ultra-thin thickness. It is scattered by concentrated heat energy, and satisfactory welding cannot be expected.

An object of the present invention is to produce a super-thin alloy-type temperature fuse by welding between a plate electrode and a low-melting-point fusible alloy foil to ensure stable electrical contact therebetween. It is in.

[0005]

According to the present invention, there is provided a method for manufacturing an alloy-type temperature fuse, comprising the steps of: providing a low-melting-point fusible alloy foil between plate electrodes having a larger heat capacity than the metal foil; In the method of manufacturing a solder alloy, an auxiliary piece having a heat capacity smaller than the heat capacity of the plate electrode is welded to both ends of the low melting point fusible alloy foil,
Thereafter, each auxiliary piece and each plate electrode are welded to each other.

[0006]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows an example of an ultra-thin alloy-type temperature fuse manufactured according to the present invention. In FIG. 1, reference numeral 1 denotes an insulating space having a central hole 11.
A heat-resistant plastic film (for example, polyethylene terephthalate, polyamide, polyimide, polyphenylene sulfide, etc.) or ceramic plate can be used. Reference numerals 2 and 2 denote plate electrodes fixed to the upper and lower surfaces of the insulating spacer 1 with an adhesive 3, and a metal foil such as a Ni foil can be used. 4 is a low melting point soluble alloy foil, 5,5
Is a metal foil auxiliary piece welded to both ends of the low melting point fusible alloy foil 4. For example, a copper foil piece is used, the low melting point fusible alloy foil 4 is accommodated in the center hole 11, and each auxiliary piece 5 is insulated. The supporting piece 5 is sandwiched between the upper and lower end faces of the support 1 and the respective plate electrodes 2, and the respective auxiliary pieces 5 and the respective plate electrodes 2 are welded by spot resistance welding or laser welding. The thickness of the low melting point fusible alloy foil 4 and the metal foil auxiliary piece 5 is usually 50 to 200 μm. Reference numeral 6 denotes a flux filled in the central hole 11. The heat capacity of the auxiliary piece 5 is smaller than the heat capacity of the plate electrode 2 and preferably equal to or less than the heat capacity of the low melting point fusible alloy foil 4.

In order to manufacture the alloy-type temperature fuse shown in FIG. 1 according to the present invention, each auxiliary piece 5 is butted to each end of the low melting point fusible alloy foil 4 and the abutting portion is heated to form a gap therebetween. Weld. As the heating at the time of welding, heating by contact of a heating block, hot air heating, direct current heating (upset welding), or the like can be used. In this welding, since the heat capacity of the auxiliary piece 5 is close to or substantially equal to the heat capacity of the low-melting-point fusible alloy foil 4, it is necessary to heat the low-melting-point fusible alloy foil quickly and reach the temperature at which the auxiliary piece can be welded. It is possible to prevent the low melting point fusible alloy foil from being overheated and melted. The low-melting-point fusible alloy foil 4 having the auxiliary pieces 5 welded to both ends in this manner is placed in the central hole 11 of the insulating spacer 1, and the hole 11 is filled with the flux 6. The plate electrodes 2 and 2 are fixed to the lower surface with an adhesive 3, and the auxiliary pieces 5 are sandwiched between the plate electrodes 2 and the upper and lower surfaces of the insulating spacer 1, respectively. And the respective plate electrodes 2 are welded by spot resistance welding or laser welding, thereby completing the production of the alloy type temperature fuse according to the present invention. The auxiliary piece 5 and the plate electrode 2
Welding is performed instantaneously and in a spot manner, so that heat conduction to the low melting point fusible alloy foil 4 during this welding can be sufficiently suppressed, and the low melting point fusible alloy foil 4 can be stably held.

In the present invention, the direct welding between the low melting point fusible alloy foil and the plate electrode is eliminated, and the auxiliary piece is welded to the low melting point fusible alloy foil. Since the heat capacity of the auxiliary piece is sufficiently close to the heat capacity of the low melting point fusible alloy foil, the plate when the low melting point fusible alloy foil is directly welded to the plate electrode is welded to the plate electrode. Since the heat capacity of the electrode is remarkably larger than that of the low melting point fusible alloy foil, the melting of the low melting point fusible alloy foil, which is caused, can be eliminated, and the low melting point fusible alloy foil and the auxiliary piece can be welded well, and the plate electrode and Since the welding with the auxiliary piece is performed by concentrating heat energy in a spot manner, the transfer of the welding heat to the low melting point fusible alloy foil can be eliminated, and the melting deformation of the low melting point fusible alloy foil can be eliminated. Therefore,
According to the present invention, in the conventional alloy-type temperature fuse shown in FIG. 5, the low melting point fusible alloy foil 4 'is welded directly to the plate electrode 2' by concentrating heat energy in a spot manner. The scattering of the low-melting-point fusible alloy that occurs in this case can also be eliminated, and stable electrical continuity can be assured by conduction through welding between the low-melting-point fusible alloy foil and the plate electrode.

FIG. 2 shows another example of an alloy type temperature fuse manufactured according to the present invention. In order to manufacture the alloy type temperature fuse according to the present invention, each auxiliary piece 5 is butt-joined to each end of the low melting point fusible alloy foil 4 and this butt portion is heated and welded, and the low melting point fusible alloy with auxiliary piece is provided. Insulation spacer 1 for alloy foil
The central hole 11 is filled with a flux 6 and the plate electrodes 2 are fixed to the upper and lower surfaces of the insulating spacer 1 with an adhesive 3.
The electrode 2 and the auxiliary pieces 5 are welded by spot resistance welding or laser welding, and the production of the alloy type temperature fuse according to the present invention is completed. Also in the production of this temperature fuse, since the heat capacity of the auxiliary piece 5 is sufficiently close to the heat capacity of the low melting point fusible alloy foil 4, it is necessary to directly weld the low melting point fusible alloy foil to the plate electrode. Since the melting of the low melting point fusible alloy foil can be eliminated and the plate electrode and the auxiliary piece are welded by concentrating heat energy in a spot manner, the thermal deformation of the low melting point fusible alloy foil is also reduced. Can be eliminated

In the alloy type temperature fuse shown in FIGS. 1 and 2, the thickness of the plate electrode is 50 μm to 200 μm.
The thickness of the low melting point fusible alloy foil and the thickness of the auxiliary piece are 50 μm or more.
200 μm, thickness of insulating spacer is almost 100 to 900
3 m and the thickness of the adhesive layer is 50 to 200 μm, and the total thickness is approximately 300 to 1000 μm.
As shown in (b) of FIG. 3 (a cross-sectional view of FIG. 3 (a)), it is used by being incorporated in a lithium ion secondary battery. In FIGS. 3A and 3B, reference numerals 71 and 72 denote a positive electrode lid and a safety valve plate whose outer periphery is caulked and fixed via a gasket 74 at an upper end 731 of a negative electrode can 73, and A denotes a space between them. Fig. 3 shows an annular ultra-thin temperature fuse according to the present invention sandwiched, respectively. In (b) of FIG.
Reference numeral 11 denotes a central hole of the insulating spacer 1.

As shown in FIG. 4, a part of the ring is an ultra-thin temperature fuse A according to the present invention, and the other part B is an auxiliary insulation space having the same thickness as the ultra-thin temperature fuse A. -It can also be used in a rugged form.

[0012]

According to the method of manufacturing an alloy-type temperature fuse according to the present invention, even if the flat-type alloy-type temperature fuse is thinned by forming a low-melting-point fusible alloy piece into a foil, a plate can be formed. Good welding between the electrode and the low melting point soluble alloy foil via the auxiliary piece,
It is possible to provide an ultra-thin alloy-type temperature fuse that can ensure stable electrical conduction between the plate electrode and the alloy-type temperature fuse even when subjected to thermal stress due to daily or seasonal temperature changes. .

[Brief description of the drawings]

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

FIG. 2 is a drawing showing another example of an alloy type temperature fuse manufactured according to the present invention.

FIG. 3 is a view showing an example of a state in which an alloy-type temperature fuse manufactured according to the present invention is installed in a battery.

FIG. 4 is a view showing another example of a state in which the alloy-type temperature fuse manufactured according to the present invention is mounted in a battery.

FIG. 5 is a view showing a conventional alloy-type temperature fuse.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Insulating spacer 11 Central hole of insulating spacer 2 Plate electrode 4 Low melting point fusible alloy foil 5 Auxiliary piece

Claims (3)

[Claims] 1. A method for manufacturing a temperature fuse in which a low melting point fusible alloy foil is provided between plate electrodes having a larger heat capacity than the metal foil, the auxiliary piece having a heat capacity smaller than the heat capacity of the plate electrode. Is welded to both ends of a low melting point fusible alloy foil, and then each auxiliary piece is welded to each plate electrode. 2. The method according to claim 1, wherein the welding between each auxiliary piece and each plate electrode is performed by spot resistance welding or laser welding. 3. A temperature fuse using a low-melting-point fusible alloy foil as a fuse element, an auxiliary piece having a heat capacity smaller than the heat capacity of the plate electrode is connected to both ends of the low-melting-point fusible alloy foil, An alloy-type temperature fuse, wherein each auxiliary piece is connected to each plate electrode.