JP2004071552A - Thin thermal fuse - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a thin thermal fuse capable of fully increasing the flux coating thickness of a portion from a fusible alloy piece to a flat lead conductor tip; to enable a film type and a resin mold type thin thermal fuses to resolve well an unstable problem at a connecting portion between the alloy piece and the lead conductor due to a bending reaction force; and to ensure an even partitioning and forming in a spherical shape of the alloy piece to prompt a smooth action for a substrate type thin thermal fuse. <P>SOLUTION: Bending projecting parts 11 are provided at lead conductor parts between ends of a fusible alloy piece 2 and film sealing portions, where the projecting parts 11 are made to serve as weirs for coating of a flux 3. <P>COPYRIGHT: (C)2004,JPO

Description

The present invention relates to a thin thermal fuse.

2. Description of the Related Art Recently, secondary batteries having a high energy density such as lithium ion secondary batteries and lithium polymer secondary batteries have been used as secondary power sources for portable electronic devices such as mobile phones and notebook computers.
In these secondary batteries, the temperature of heat generated at the time of abnormality is high due to its large energy density.
Therefore, it is known to mount a thin thermal fuse and cut off a current-carrying circuit of the battery before the high temperature is reached to prevent a serious accident from occurring.
For example, as in the battery pack shown in FIG. 16, a thin thermal fuse P ′ is mounted on the side of a flat case 8 for storing a secondary battery, and a predetermined temperature is set so that the secondary battery can be disconnected from the load by operating the thermal fuse. The circuit board 81 is connected to the secondary battery.
In FIG. 16, reference numerals 1 'and 1' denote flat lead conductors of a thin thermal fuse, and reference numerals 82a and 82b denote external electrodes of a battery pack. The lead conductors and the electrodes are connected by spot resistance welding or the like.
As the thin thermal fuse, a film type, a substrate type, a resin mold type and the like are known.
FIG. 17A is a plan view partially showing a cross section of an example of a conventionally known film type, and FIG. 17B is a roll cross-sectional view of FIG. 17A.
In FIG. 17, reference numeral 41 'denotes a lower resin film, 1' and 1 'denote a pair of flat lead conductors disposed on the lower resin film, and 2' denotes a pair connected between the lead conductors 1 'and 1'. The molten alloy pieces, 3 ', are fluxes applied on the fusible alloy pieces and on the lead conductor portions near the fusible alloy pieces. Reference numeral 42 'denotes an upper resin film, and its periphery is sealed to the lower resin film 41' and the flat lead conductor 1 'while being curved on the projecting coating flux 3'.

FIG. 18A is a plan view partially showing another example of a conventionally known film type in a cross-sectional view, and FIG. 18B is a cross-sectional view of FIG.
In FIG. 18, reference numeral 41 'denotes a lower resin film, and reference numerals 1' and 1 'denote a pair of flat lead conductors. The front half is fixed to the lower surface of the film 41', and the front end 101 'is squeezed out. Appears on the top of the film. 2 'is a fusible alloy piece connected between the lead conductor exposed portions 101', 101 ', and 3' is applied to the fusible alloy piece 2 'and a portion of the conductor exposed portion 101' near the fusible alloy end. Flux. Reference numeral 42 'denotes an upper resin film whose periphery is sealed to the lower resin film 41' and the flat lead conductor 1 'while being curved on the projecting covering flux 3'.

FIG. 19A is a plan view showing a conventionally-known resin mold type, and FIG. 19B is a cross-sectional view taken along a line in FIG.
In FIG. 19, 1 'and 1' are flat lead conductors, 2 'is a fusible alloy piece connected between the flat lead conductors, and 3' is applied to the fusible alloy piece and a lead conductor portion near one end of the fusible alloy. Flux. Numeral 40 'denotes a resin mold coating, which is provided by dip coating of a curable resin liquid such as an epoxy resin.

FIG. 20A is a plan view partially showing a cross section of an example of a conventionally known substrate type, and FIG. 20B is a cross-sectional view taken along the line B in FIG.
In FIG. 20, 51 'is an insulating base such as a ceramic plate, 6' and 6 'are a pair of electrodes provided on the insulating base, 1' and 1 'are flat connected to the electrodes 6' and 6 '. The lead conductor 2 'is a fusible alloy piece connected between the electrodes 6' and 6 ', and 3' is a fusible alloy piece and a flux applied from one end of the fusible alloy to the tip of the lead conductor. 52 'is a cover plate such as a ceramic plate, and 7' is an adhesive for sealing the periphery of the cover plate 52 'to the insulating base 51' and the flat lead conductor 1 '. A cover plate 52 'is placed, and a two-part adhesive 7' such as an epoxy resin is applied around the plate.

The operating mechanism of the thermal fuse is as follows.
The melting point of the fusible alloy piece 2 'is set so that the fusible alloy piece can be blown at a temperature sufficiently lower than the abnormal heat generation temperature with respect to the abnormal heat generation of the secondary battery.
Thus, when the fusible alloy piece is melted, the molten alloy is wetted and pulled to the electrode or the end of the lead conductor under the coexistence with the already-melted flux, and the wetting is enlarged by spheroidization to form the molten alloy. When the splitting is promoted and the split cuts off the current and stops the heat generation of the battery, the split molten alloy is solidified and the non-return cutoff is terminated.
The flux is intended to prevent oxidation of the easily oxidizable fusible alloy piece, and to dissolve the oxide unavoidably contained in the fusible alloy piece by activating the flux by heating. In addition to accurately melting the piece at a predetermined melting point, it has the effect of promoting the wetting of the molten alloy from the surface energy surface to the electrodes and the ends of the lead conductors, and is indispensable for securing a space when the molten alloy is spheroidized. Therefore, it is necessary to allow a sufficient amount of flux to exist also at the electrode and the end of the lead conductor.

In the application of the flux of the thermal fuse, a liquid flux that is heated and melted is usually adhered at a predetermined outer shape, and is cooled and solidified as shown in FIG. In this case, when considering the longitudinal section of the coating flux, as shown in (b) of FIG. 21, the surface tension r _m of the electrode or the _like, the surface tension of the r _L coagulation immediately preceding _flux, the flux and the electrode such as surface Assuming that the interfacial tension between and is r _mL and the contact angle is α,

r _m = r _L cosα + r _mL

The angle gradually decreases from the contact end to the center, becomes 0 at the center, and the center height y increases as the distance x from the center to the contact end increases. Therefore, in order to cover the end of the lead conductor with the flux, it is necessary to considerably increase the center height y.

In the above film type thin thermal fuse, since the upper resin film is considerably curved and sealed on the projecting coating flux, the thermal fuse body is warped and bent, and the connection point between the fusible alloy piece and the flat lead conductor Damage is a problem.
That is, the bending radius of the initial upper resin film abutted on the projecting coating flux in a curved state is r ′, the bending rigidity of the upper resin film is (EI) ′, and the bending rigidity of the thermal fuse body portion excluding the upper resin film is r ′. (EI), the bending reaction force m acting on the thermal fuse body is

{M = 1 / {r "[1+ (EI) '/ (EI)]}

The bending reaction force m becomes large due to the large bending rigidity of the lead conductor, and a large peeling force acts on the connection interface between the flat lead conductor and the fusible alloy piece, thereby reducing the safety of the connection interface. Be inhibited.

In the above-mentioned resin molded thin thermal fuse, since a large amount of flux is applied to the upper surface side of the fusible alloy piece, it is inevitable that the bending neutral surface will deviate from the thickness center surface of the flat lead conductor, The temperature fuse body is bent and deformed due to the temperature change based on the difference in linear expansion coefficient, cross-sectional area and Young's modulus between the lead conductor and the lead conductor, but the bending reaction force acting on the lead conductor having high bending rigidity increases, Also in this case, a peeling force acts on the connection interface between the flat lead conductor and the fusible alloy piece, and the safety of the connection interface is impaired.

In contrast to these film-type thin thermal fuses and resin-mold-type thin thermal fuses, the substrate-type thin thermal fuse has a large overall bending stiffness (EI). Therefore, even if the bending moment (M) acts, The bending radius of curvature (r = EI / M) can be kept sufficiently large, bending deformation can be substantially eliminated, and instability of the above-mentioned connection point between the fusible alloy piece and the lead conductor can be avoided.
However, when the flux of the thermal fuse is applied, the three-dimensional shape of the flux after cooling and solidification becomes a tall dome-shaped curved surface. Therefore, as shown in FIG. As long as the cover plate 52 'is placed, the support state of the cover plate 52' is unavoidably unstable due to the contact between the curved surface and the flat surface, and the cover plate 52 'swings with respect to the long axis center line to break the balance. I can't escape tilting. Thus, as shown in FIG. 22 (b), the above-mentioned spheroidizing of the fusible alloy piece causes the flux amount for the divided molten alloys 23a ′ and 23b ′ when the fusible alloy piece divides and spheroidizes on both sides. In this case, the spheroidization of the molten alloy on the side with a smaller amount of flux is slowed down more than the spheroidization of the molten alloy on the other side, resulting in a delay in the cutting operation. At this time, since the inclination angle of the insulating cover plate 52 'is different for each product, variation in the dividing operation is caused.

As described above, it is necessary that a sufficient amount of flux be present at the electrode or the end of the lead conductor in the thermal fuse.
Conventionally, it has been known that a flat lead conductor portion near one end of a fusible alloy is protruded by a punch, and this protrusion is used as a weir for a coating flux to increase the flux coating thickness of the lead conductor portion near one end of the fusible alloy. (See Patent Document 1).

JP-A-2001-52582

However, in punching, it is necessary to increase the thickness of the flat lead conductor to some extent in order to prevent cracking, which makes it difficult to lower the bending rigidity of the flat lead conductor, and reduces the bending reaction force of the film type and resin mold type described above. It is not suitable for avoiding instability of the connection point between the fusible alloy piece and the lead conductor.
In addition, in the punching process, the protrusion width is narrower than the flat lead conductor width, and furthermore, it is easy to have a radius at the corner of the protrusion outer surface, and therefore, it is difficult to eliminate the instability of the support state of the cover plate in the substrate type. In addition, the above-described problem of the decrease in the cutting operability due to the fixed inclination of the cover plate cannot be solved.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a thin type thermal fuse in which a flux covering thickness from one end of a fusible alloy to a tip of a flat lead conductor can be sufficiently increased and a thin type thermal fuse of a film type or a resin mold type is bent. It can solve the problem of instability of the connection point between the fusible alloy piece and the lead conductor based on the reaction force well, and for the board type thin thermal fuse, guarantee the uniform spheroidization of the fusible alloy piece evenly. The point is to ensure smooth operation.

The thin thermal fuse according to claim 1, wherein the fusible alloy piece is connected between the flat lead conductors in a state where the thickness center of the fusible alloy piece is positioned above the thickness center of the flat lead conductor. And flux is adhered to the lead conductor portion in the vicinity thereof, and these are air-tightly led out of the lead conductor by the lower resin film and the upper resin film and sealed, and the upper resin film is formed on the protruding contents on the inner surface thereof. In the thermal fuse formed by bending, a bent convex portion is provided on a lead conductor portion between one end of a fusible alloy and a film sealing portion, and the convex portion serves as a weir for application of the flux. And

3. The thin thermal fuse according to claim 2, wherein a pair of flat lead conductor ends are fixed to the lower surface of the lower resin film, and a portion separated from the tip of each lead conductor by a predetermined distance is swelled. A fusible alloy piece is connected between the exposed portions, and a flux is attached to the fusible alloy piece and the exposed portion near the end of the fusible alloy piece, and the upper resin film is In the thermal fuse, which is sealed around the lower resin film and the upper resin film is curved on the protruding contents on the inner surface side, the convex portion is formed in the vicinity of one end of the fusible alloy at the lead conductor exposed portion. The convex portion is provided as a weir for the flux application.

4. The thin thermal fuse according to claim 3, wherein a pair of flat lead conductor ends are fixed to a lower surface of the lower resin film, and a portion separated by a predetermined distance from a tip of each lead conductor has a predetermined width and has a predetermined width. It is bent into a land portion on the substantially flat upper surface and a bent convex portion on the rear end side of the land portion and is exposed on the film upper surface, and a fusible alloy piece is connected between the exposed land portions, Flux is applied to almost the entire surface of the fusible alloy piece and the land portion with the bent convex portion as a weir, and the upper resin film is sealed around the lower resin film while the upper resin film is It is characterized by being curved on the protruding contents on the inner surface side, and an auxiliary resin film is adhered to the lower surface of the lower resin film.

According to claim 4, in the thin thermal fuse according to any one of claims 1 to 3, the upper resin film is thinner than the lower resin film.

In the thin thermal fuse according to claim 5, a fusible alloy piece is connected between the flat lead conductors, and a flux is adhered to the fusible alloy piece and a lead conductor portion at a predetermined distance from the fusible alloy piece. In the thermal fuse in which the resin layer is surrounded and surrounded, a bent convex portion is provided on a lead conductor portion at a predetermined distance from one end of the fusible alloy, and the convex portion serves as a weir for the application of the flux. It is characterized by.

According to claim 6, in the thin thermal fuse according to any one of claims 1 to 5, a rounded upper end on both sides of the bent convex portion is provided.

The thin thermal fuse according to claim 7, wherein a pair of electrodes are provided on the insulating base, a flat lead conductor is connected to each electrode, and a fusible alloy piece is connected between these electrodes. In a temperature fuse in which a flux is applied from one end of the alloy to the tip of the flat lead conductor and a watertight insulating coating is provided on the insulating base, the flat lead is separated from the tip of the flat lead conductor or the fusible alloy piece by a predetermined distance. A bent projection is provided on the conductor portion, and the projection serves as a weir for the application of the flux.

The thin thermal fuse according to claim 9, wherein a pair of flat lead conductors is provided on the insulating base, a fusible alloy piece is connected between the flat lead conductors, and the fusible alloy piece and the flat lead conductor from one end of the fusible alloy. In the thermal fuse in which the flux is attached over the tip portion and the water-tight insulating cover is provided on the insulating base, a bent convex portion is formed on the lead conductor portion at a predetermined distance from the tip of the flat lead conductor or one end of the fusible alloy. The convex portion is provided as a weir for the application of the flux.

According to claim 8, in the thin thermal fuse of claim 7, one end of the fusible alloy is also connected to the flat lead conductor, and according to claim 10, in the thin thermal fuse of any of claims 7 to 9, the watertight insulating coating is provided. The body is composed of a cover plate in contact with the bent projections at the tips of the two flat lead conductors, and an adhesive sealing around the cover plate to an insulating base.

The thin thermal fuse according to claim 11, wherein the fusible alloy piece is connected between the flat lead conductors in a state where the thickness center of the fusible alloy piece is positioned above the thickness center of the flat lead conductor. And flux is adhered to the lead conductor portion in the vicinity thereof, and these are air-tightly led out of the lead conductor by the lower resin film and the upper resin film and sealed, and the upper resin film is formed on the protruding contents on the inner surface thereof. In the thermal fuse formed by bending, a bent convex portion is provided at the tip of the flat lead conductor, one end of a fusible alloy is connected to the front surface of the convex portion, and the convex portion serves as a weir for the application of the flux. It is characterized by.

According to a twelfth aspect, in the thin thermal fuse according to any one of the seventh to eleventh aspects, a radius is attached to both upper ends on both sides of the convex portion. Is thinner than the lower resin film. In the fourteenth aspect, in the thin thermal fuse according to any one of the first to thirteenth aspects, the width of the lead conductor portion in the thermal fuse body is wider than the width of the fusible alloy piece. According to a fifteenth aspect, in the thin thermal fuse of the fourteenth aspect, the lead conductor portion in the thermal fuse body is formed by rolling.

According to a sixteenth aspect, in the thin thermal fuse according to any one of the first to fifteenth aspects, the lead conductor is made of Ni, and at least the tip portion is made of one of Sn, Cu, Ag, and Au, or an alloy containing these as a main component. In the thin thermal fuse according to any one of the first to sixteenth aspects, the heating element for blowing the fusible alloy piece is provided.

According to Claim 18, in the thin thermal fuse according to any one of Claims 1 to 17, the fusible alloy piece has an In-Sn-Bi-based alloy, a Bi-Sn-Sb-based alloy, an In-Sn-based alloy, or an In-Bi-based alloy. , Bi-Sn-based alloy or In-based alloy, wherein the composition of the In-Sn-Bi-based alloy is (1) 43% <Sn ≦ 70%, 0.5% ≦ In ≦ 10%, the remaining Bi, (2) 25% ≦ Sn ≦ 40%, 50% ≦ In ≦ 55%, remaining Bi, (3) 25% <Sn ≦ 44%, 55% <In ≦ 74%, 1% ≦ Bi <20%, ( 4) 46% <Sn ≦ 70%, 18% ≦ In <48%, 1% ≦ Bi ≦ 12%, (5) 5% ≦ Sn ≦ 28%, 15% ≦ In <37%, remaining Bi (however, Bi 57.5%, In 25.2%, Sn 17.3%, Bi 54%, In 29.7%, Sn 16.3% (6%) 10% ≦ Sn ≦ 18%, 37% ≦ In ≦ 43%, residual Bi, (7) 25% <Sn ≦ 60%, 20% ≦ In <50%, 12% <Bi ≦ 33%, (8) Ag, Au, Cu, Ni, Pd, Pt, Sb, Ga, Ge, P in 100 parts by weight of any of (1) to (7) (7) 33% ≦ Sn ≦ 43%, 0.5% ≦ In ≦ 10%, residual Bi, (10) 47% ≦ Sn ≦ Add 3 to 5 parts by weight of Bi to 100 parts by weight of 49%, 51% ≦ In ≦ 53%, (11) 40% ≦ Sn ≦ 46%, 7% ≦ Bi ≦ 12%, remaining In, (12) 0.3% ≦ Sn ≦ 1.5%, 51% ≦ In ≦ 54%, remaining Bi, (13) 2.5% ≦ Sn ≦ 10%, 25% ≦ Bi ≦ 35%, remaining In, (14) (9 (1) Ag, Au, Cu, Ni, Pd, Pt, Sb, Ga, Ge, P or a total of 0.01 to 7 parts by weight were added to 100 parts by weight of any of (13) to (15). ) 10% ≦ Sn ≦ 25%, 48% ≦ In ≦ 60%, 100% by weight of remaining Bi, one or more of Ag, Au, Cu, Ni, Pd, Pt, Sb, Ga, Ge, P 0.01 to 7 parts by weight in total, and the composition of the Bi-Sn-Sb-based alloy is (16) 30% ≦ Sn ≦ 70%, 0.3% ≦ Sb ≦ 20%, the remaining Bi, (17) (16) ), 100 or more parts by weight of Ag, Au, Cu, Ni, Pd, Pt, Ga, Ge, P, or a total of 0.01 to 7 parts by weight are added, and the composition of the In-Sn alloy is ( 18) 52% ≦ In ≦ 85%, residual Sn, (19) Ag, Au, Cu, Ni, Pd in 100 parts by weight of (18) One or more of Pt, Sb, Ga, Ge, and P are added in a total amount of 0.01 to 7 parts by weight, and the composition of the In-Bi alloy is (20) 45% ≦ Bi ≦ 55%, the remaining In, ( 21) One or more of Ag, Au, Cu, Ni, Pd, Pt, Sb, Ga, Ge and P are added to 100 parts by weight of the composition of (20) in a total amount of 0.01 to 7 parts by weight, Bi The composition of the Sn-based alloy is (22) 50% <Bi ≦ 56%, the remaining Sn, (23) 100 parts by weight of (22) are Ag, Au, Cu, Ni, Pd, Pt, Ga, Ge, P One or two or more kinds are added in a total of 0.01 to 7 parts by weight, and the composition of the In-based alloy is (24) 100 parts by weight of In, Au, Bi, Cu, Ni, Pd, Pt, Ga, Ge, and P. One or two or more kinds are added in a total amount of 0.01 to 7 parts by weight, (25) 90% ≦ In ≦ 99.9%, 0.1% ≦ One or more of Au, Bi, Cu, Ni, Pd, Pt, Ga, Ge and P are added to 100 parts by weight of Ag ≦ 10% in a total amount of 0.01 to 7 parts by weight, (26) 95% One or more of Au, Bi, Cu, Ni, Pd, Pt, Ga, Ge, and P are added to 100 parts by weight of ≦ In ≦ 99.9% and 0.1% ≦ Sb ≦ 5% in a total amount of 0.1%. Any one of the additions of 01 to 7 parts by weight is used.

In claim 19, the thin thermal fuse according to any one of claims 1 to 16 or 18 is used as a current fuse.

In the thermal fuse according to the present invention, the bent protrusion provided at the leading end of the lead conductor or the bent protrusion provided at the leading end of the lead conductor is used as a weir to allow the flux to adhere to the vicinity of one end of the fusible alloy with a sufficient thickness. Therefore, the split spheroidization of the molten alloy on both sides can be quickly caused, and quick operation can be guaranteed.
In this case, the weir can be favorably provided even if the lead conductor is made thin. Particularly, for a film type thin thermal fuse, the lead conductor of bending reaction force generated due to the curved sealing of the upper resin film. Since the burden can be reduced by reducing the thickness of the lead conductor and reducing the bending rigidity, the bonding interface between the lead conductor and the fusible alloy piece can be stably maintained, and stable operability can be guaranteed.
In addition, for resin molded thin thermal fuses, the action of the lead conductor of the bending moment generated due to the heat cycle can be reduced by thinning the lead conductor and reducing the bending rigidity. Can be stably maintained, and stable operability can be guaranteed.
Still further, for a thin thermal fuse using an insulating cover plate, the insulating cover plate can be stably supported by the bent protrusion provided at the tip of the lead conductor or the bent protrusion provided at the tip of the lead conductor. In contrast, it is possible to guarantee the parallel holding of the insulating cover plate without tilting, to secure the same space on both sides for the spheroidization of the molten fusible alloy piece, and to reduce the variation in the spheroidization. Operability can be sufficiently improved.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1A is a plan view showing a cross section of a part of one embodiment of the thin thermal fuse according to the present invention, and FIG. 1B is a cross-sectional view taken along the line R in FIG.
In FIG. 1, reference numerals 1 and 1 denote a pair of flat lead conductors, each of which is provided with a convex portion 11 at a position separated by a predetermined distance from the tip. Numeral 2 is a fusible alloy piece joined by welding or the like between the upper surfaces of the tip portions of the flat lead conductors 1 and 1, and spot welding, laser welding or the like can be used for welding. Numeral 3 denotes a flux, which is adhered to the fusible alloy piece 2 and a portion extending from one end of the fusible alloy to the bent convex portion 11 of the lead conductor. The convex portion 11 is used as a weir for flux application, and the fusible alloy piece 12 is used. The thickness of the flux coating from the portion of the lead conductor to the bent projection 11 of the lead conductor is made sufficiently thick. Reference numeral 41 denotes a lower resin film, and reference numeral 42 denotes an upper resin film. The front half of the flat lead conductors 1, 1 and the fusible alloy piece 2 are sandwiched between these resin films 41, 42, and the upper resin film 42 is formed. The periphery is sealed to the lower resin film 41 which is horizontally held while being curved on the projecting coating flux 3.

FIG. 2A is a plan view showing a cross section of a part of another embodiment of the thin thermal fuse according to the present invention, and FIG. 2B is a cross-sectional view taken along a roll line in FIG. is there.
In FIG. 2, reference numeral 41 denotes a lower resin film. Reference numerals 1 and 1 denote a pair of flat lead conductors whose first half is fixed to the lower surface of the lower resin film 41 and whose upper surface is substantially flush with the lower resin film surface at a position separated by a predetermined distance from the lead conductor tip. The rear end portion of the convex portion 101 is bulged at once to the convex portion 11 so as to appear on the upper surface side of the lower resin film 41, so that the lower resin film 41 and the flat lead conductor 1 All interfaces are joined by fusion or adhesive. Reference numeral 2 denotes a fusible alloy piece, which is connected to a portion 101 of the lead conductor exposed portion substantially flush with the upper surface of the lower resin film by welding, for example, spot resistance welding, laser welding, or the like. Numeral 3 denotes a flux, which is attached to the fusible alloy piece 2 and to the portion from the fusible alloy piece to the convex portion 11 of the lead conductor. The flux coating thickness of the portion reaching the convex portion 11 of the conductor is made sufficiently thick. Reference numeral 42 denotes an upper resin film, the periphery of which is curved on the projecting coating flux 2 and the periphery of which is sealed to the lower resin film 41 which is horizontally held.

In the embodiment shown in FIG. 2, a part of the lead conductor 1 on the upper surface of the lower resin film is exposed by swelling, and both sides of the exposed part are left unprocessed. (B) As shown in (b) (plan view) and (b) [cross-sectional view taken along the roll in (a) of FIG. 3], the upper surface is located at a predetermined distance from the position near the tip of the lead conductor. The land portion 101a, which is substantially flush with the upper surface of the resin film 41, is bulged at a time to form a convex portion 11a on the rear side, and the auxiliary resin film 43 is fused on the back surface of the lower resin film 41 to ensure watertightness. It can also be adhered by wearing or an adhesive. Alternatively, as shown in (a) (a plan view) and (b) (a cross-sectional view taken along a roll in (a) of FIG. 4) of FIG. 4, the upper surface extends up to a position at a predetermined distance from the tip of the lead conductor. The land portion 101b, which is substantially flush with the upper surface of the lower resin film 41, is bent all at once to form a bent projection 11b, which extends over the entire width of the lead conductor. An auxiliary resin film 43 can be attached to the back surface of the resin film 41 by fusion or an adhesive.

補助 The auxiliary resin film 43 also has an effect of complementing the lack of insulation strength between the lead conductor tips when the auxiliary resin film in FIG. 2 does not exist.

In the film type thin thermal fuse shown in FIGS. 1 to 4, the thickness center of the fusible alloy piece 2 is located above the thickness center of the flat lead conductor 1 and between the flat lead conductors 1 and 1. Since the fusible alloy piece 2 is connected, the flux 3 is attached to the fusible alloy piece and the lead conductor portion near the fusible alloy piece, and the upper resin film 42 is curved on the protruding contents on the inner surface side, warpage occurs. . In this case, the initial bending radius of the upper resin film 42 abutted on the projecting coating flux in a curved state is r ′, the bending rigidity of the upper resin film 42 is (EI) ′, and the temperature fuse body portion excluding the upper resin film is Assuming that the bending rigidity is (EI), the bending reaction force m acting on the thermal fuse body portion is as described above.

{M = 1 / {r "[1+ (EI) '/ (EI)]}

Given by
The weir for the application of the flux 3 is provided by the bent protruding portion 11, 11a or 11b of the flat lead conductor. Even if the flat lead conductor 1 is made as thin as 100 μm, the protrusion is formed by a simple bending process. 11, 11a or 11b can be formed, and the occurrence of cracks can be eliminated. However, in the projection 11 of the embodiment shown in FIG. 2, the lead conductor 1 is simultaneously processed on the upper surface of the lower resin film 41 at the time of bulging into the substantially flat projection 101. In this case, even if the thickness of the lead conductor is reduced, the occurrence of cracks can be sufficiently prevented.
Therefore, it is possible to reduce the bending stiffness (EI) of the thermal fuse body portion and to reduce the bending reaction force m acting on the thermal fuse body portion, and the bonding interface between the flat lead conductor and the fusible alloy piece based on the bending reaction force m. Can be reduced, and the stability of the bonding interface can be increased.

In the thin-film thermal fuse of the film type shown in FIGS. 1 and 2, the thickness of the upper resin film 42 is made smaller than the thickness of the lower resin film 41 to reduce (EI) ′, thereby reducing the bending reaction force m. Therefore, the stability of the bonding interface can be further enhanced.

In the thin thermal fuse of the film type shown in FIGS. 3 and 4, (EI) ′ is reduced by making the thickness of the upper resin film 42 smaller than the total thickness of the lower resin film 41 and the auxiliary resin film 43. By reducing the size, the bending reaction force m can be reduced, and the stability of the bonding interface can be further enhanced.

In any of the above embodiments, sealing between the resin films can be performed by high frequency welding, ultrasonic welding, or an adhesive, and the sealing between the lead conductor and the resin film can be performed by pressing the lead conductor under pressure on the outer surface of the film. Can be performed by electromagnetic induction heating or heat plate contact heating.

FIG. 5A is a plan view showing another embodiment of the thin thermal fuse according to the present invention, and FIG. 5B is a cross-sectional view of the thin thermal fuse shown in FIG.
In FIG. 5, reference numerals 1 and 1 denote a pair of flat lead conductors, each of which is provided with a bent convex portion 11 at a position separated by a predetermined distance from the tip. Reference numeral 2 denotes a fusible alloy piece, which is connected between the lead conductor tip portions by welding, for example, spot resistance welding, laser welding, or the like. Reference numeral 3 denotes a flux, which is adhered to the fusible alloy piece 2 and a portion extending from the fusible alloy piece 2 to the bent convex portion 11 of the lead conductor. The thickness of the flux coating from the end to the bent protrusion 11 of the lead conductor is sufficiently thick. Reference numeral 40 denotes a resin coating layer provided so as to surround the fusible alloy pieces, the flux, and the end portions of the lead conductor, and is coated by, for example, immersion coating in a two-part curable resin liquid such as an epoxy resin liquid.

In the embodiment shown in FIG. 5, since the Young's modulus of the flux is extremely small mechanically, it can be handled as a composite of the coating resin 40 and the fusible alloy pieces 2-lead conductors 1, 1, and the coating resin side The bending stiffness is (EI) ′, the bending stiffness on the fusible alloy piece-lead conductor side is (EI), and the bending moment generated when the temperature changes due to the difference in Young's modulus, cross-sectional area and thermal expansion coefficient is M Then, the bending moment m borne by the fusible alloy piece-lead conductor side is

{M = M / {1 + [(EI) '/ (EI)]}

Given by
The weir for the flux 3 is provided by the bent protruding portion 11 of the flat lead conductor. Even when the flat lead conductor 1 has a thin thickness of 100 μm, the bending of the protruding portion is a simple bending process. Therefore, the bending moment (m) acting on the lead conductor can be reduced by reducing the bending stiffness (EI) on the fusible alloy piece-lead conductor side, and the flat lead conductor can be melted based on the bending moment m. The peeling force acting on the joint interface with the alloy piece can be reduced, and the stability of the joint interface can be enhanced.

In the above description, if the upper ends of both sides of the bent convex portion 11 are rounded, it is possible to eliminate local damage to the upper resin film when the upper end is an edge and local thinning due to a decrease in surface tension of the coating resin.

FIG. 6A is a plan view showing a part of another embodiment of the thin thermal fuse according to the present invention, which is different from the above, and FIG. 6B is a cross-sectional view taken along the line B in FIG. It is.
In FIG. 6, reference numeral 51 denotes an insulating base having excellent heat resistance and thermal conductivity, for example, a ceramic plate such as alumina ceramics. Reference numerals 6 and 6 denote a pair of electrodes provided on both sides in the longitudinal direction of one surface of the insulating base 51, which can be provided by applying and baking a conductive paste. Reference numerals 1 and 1 denote flat lead conductors connected to the electrodes 6 and 6 by welding or the like, for example, spot resistance welding, laser welding, or soldering, and are provided with upwardly bent convex portions 110 over the entire width of the tip. Reference numeral 2 denotes a fusible alloy piece connected between the electrodes 6 and 6 by welding or the like, and spot welding, laser welding, or the like can be used for welding. Numeral 3 denotes a flux which covers the entire fusible alloy piece 2 and one end of the fusible alloy from the one end of the fusible alloy, and covers the upwardly bent convex part 110 of the lead conductor tip as a weir.
Reference numeral 52 denotes an insulating cover plate such as a ceramic plate, which is smaller than the insulating base 51. Reference numeral 7 denotes an adhesive, for example, a two-part cold curing adhesive such as an epoxy resin, which is insulated from the periphery of the insulating cover plate 52 in a state where the insulating cover plate 52 is supported by the upwardly bent projections 110, 110 of the lead conductor tips. The space between the substrate 51 and the base 51 is sealed with an adhesive 7.

In the embodiment shown in FIG. 6, since the upwardly bent convex portion 110 at the tip of the lead conductor is provided with a predetermined width at the tip of the lead conductor, the insulating cover plate 52 is held parallel to the insulating base 51 without inclination. As a result, the space and space for the spheroidization of the molten alloy (melted fusible alloy piece) can be made constant, and as a result, a smooth and smooth dividing operation can be promoted.

In the embodiment of FIG. 6, in order to reduce the amount of the adhesive 7 to be used and to prevent the adhesive from spreading inward, FIGS. 7 (A) and 7 (B) [FIG. As shown in FIG. 2, a ridge 521 is provided around the back surface of the insulating cover plate 52, the gap between the ridge 521 and the lead conductor 1, and the ridge 521 and the insulating base 51 are provided. Can be sealed with the adhesive 7.
In this case, even if the height of the protrusion 521 is smaller than the height of the lead conductor tip 110, and the insulating cover 52 is supported by the bent protrusions 110, 110 at the both lead conductor tips, the insulating base 51 is formed in the same manner as described above. As a result, the parallel holding of the insulating cover 52 without inclination can be guaranteed, and the space for the spheroidization of the molten alloy (melted fusible alloy piece) can be made constant, thereby promoting smooth and smooth dividing operation. Can be. Accordingly, a smooth disconnection operation without variation can be guaranteed while keeping the thickness of the thermal fuse main body portion sufficiently thin.

FIG. 8A is a plan view showing, in partial cross section, another embodiment of the thin thermal fuse according to the present invention which is different from the above, and FIG. 8B is a cross-sectional view of FIG. It is.
In FIG. 8, reference numeral 51 denotes an insulating base. Reference numerals 1 and 1 denote a pair of flat lead conductors. A bent convex portion 11 is provided at a position separated from the distal end by a predetermined distance, and the distal end portion including the convex portion 11 is fixed to the insulating base 51. Reference numeral 2 denotes a fusible alloy piece connected between the lead conductors 1 and 1 by welding or the like. For the welding, spot resistance welding, laser welding, or the like can be used. Numeral 3 denotes a flux that covers the entire fusible alloy piece 2 and the end of the fusible alloy from the end of the fusible alloy, and is coated with the bent convex part 11 as a weir.
Reference numeral 52 denotes an insulating cover plate such as a ceramic plate, which is smaller than the insulating base 51 as in the embodiment shown in FIG. Reference numeral 7 denotes an adhesive, for example, a two-part cold-setting adhesive such as an epoxy resin. The adhesive 7 covers the periphery of the insulating cover plate 52 in a state where the insulating cover plate 52 is supported by the bent protrusions 11 of the lead conductors 1, 1. The space between the insulating substrate 51 and the insulating substrate 51 is sealed with an adhesive 7.

Also in the embodiment shown in FIG. 8, in order to reduce the amount of the adhesive 7 used and to prevent the adhesive from spreading to the inside, FIG. 9A and FIG. (A), a ridge 521 is provided around the back surface of the insulating cover plate 52, and a gap between the ridge 521 and the lead conductor 1 and the ridge 521 are formed. The gap between the insulating base 51 and the insulating substrate 51 can be sealed with the adhesive 7. In this case, too, the height of the protruding ridge 521 is smaller than the height of the bent protruding portion 11 at the tip of the lead conductor 1. Even if the plate 52 is supported by the bent protruding portions 11 of the lead conductors 1, 1, the holding of the insulating cover plate 52 without inclination relative to the insulating base 51 can be assured in the same manner as described above. (Empty for spheroidization of (melted fusible alloy pieces)) Results that can space constant, it is possible to promote a smooth cutting operation with no unevenness, thus ensure a smooth cutting operation with no unevenness while retaining sufficiently reduce the thickness of the temperature fuse body part.

In the embodiment shown in FIGS. 6 to 9 as well, if the upper ends on both sides of the bent protrusions 11 and 110 are rounded, it is possible to eliminate the possibility of local damage to the insulating cover plate when the upper ends are edges.

When manufacturing the thin thermal fuse shown in FIGS. 8 and 9, usually, the tip portions of the lead conductors 1 and 1 are fixed to the insulating base 51, and the fusible alloy piece 2 is connected between the lead conductors 1 and 1. The insulating cover plate 52 is placed on the bent protrusions 11 of the two lead conductors 1, 1, and the periphery of the insulating base 51 and the insulating cover plate 52 is sealed with the adhesive 7. An adhesive or heat fusion can be used for fixing the leading end portions of the lead conductors 1 and 1 having the bent convex portions to the insulating base 51.
In the case of heat fusion, a thermoplastic resin base is used as the insulating base 51, and insulation can be sufficiently ensured even if the tip of the flat lead conductor 1 is cut into the insulating base 51 at the depth of its thickness. It is desirable that the thickness of the thermoplastic resin insulating substrate 51 be about two to three times the thickness of the flat lead 1.
Further, a groove for fitting the tip of the flat lead conductor 1 may be provided on the upper surface of the insulating base 51, and the tip of the flat lead conductor 1 may be fitted.

FIG. 10A is a plan view showing a cross section of a part of another embodiment of the thin thermal fuse according to the present invention, which is different from the above, and FIG. is there.
In FIG. 10, reference numeral 51 denotes the above-described insulating base; Reference numerals 1 and 1 denote flat lead conductors connected to the electrodes 6 and 6 by welding or the like, for example, spot resistance welding, laser welding, or soldering, as described above. Reference numeral 2 denotes a fusible alloy piece connected between the electrodes 6 and 6 by welding or the like as described above. Reference numeral 3 denotes a flux which covers the entire fusible alloy piece 2 and the end of the fusible alloy from the one end of the fusible alloy to the lead conductor tip convex part 110 as described above, and is coated with the upward bent convex part 110 of the lead conductor tip as a weir.
Reference numeral 53 denotes a water-tight resin mold layer, which can be provided, for example, by immersion coating in a two-part, room-temperature curing resin liquid such as an epoxy resin.

In the embodiment shown in FIGS. 6, 7 and 10, by adjusting the distance between the front end of the electrode and the front end of the conductor, a weir for the flux can be provided at a desired position of the electrode, so that the molten alloy is sufficiently wetted on the electrode 6. To effectively promote the division and spheroidization.

As shown in FIGS. 11 and 12, the end of the fusible alloy piece 2 is also connected to the front surface of the upwardly bent convex portion 110 of the lead conductor by welding or the like, as shown in FIGS. Or can be connected only to the front surface of the upwardly bent convex portion 110.
In the embodiment shown in FIGS. 6, 7, and 10, the bent protrusion 110 may be the bent protrusion 11 shown in FIGS. Further, in the embodiment shown in FIGS. 8 and 9, the bent protrusion 11 may be the bent protrusion 110 shown in FIGS. 6, 7 and 10.

FIG. 13A is a plan view showing a cross section of a part of another embodiment of the thin thermal fuse according to the present invention, and FIG. 13B is a cross-sectional view taken along a roll line in FIG. is there.
In FIG. 13, reference numerals 1 and 1 denote a pair of flat lead conductors, the ends of which are bent upward to form convex portions 110. Numeral 2 denotes a fuse element joined by welding or the like between the front faces of the upwardly bent convex portions 110 at the ends of the two flat lead conductors 1 and 1, and laser welding or the like can be used. Numeral 3 denotes a flux, in which the upwardly bent protruding portion 110 of the lead conductor is used as a weir of the flux, and the thickness of the flux coating is sufficiently large. 41 is a lower resin film, 42 is an upper resin film, and the front half of the flat lead conductors 1, 1 and the fuse element 2 are sandwiched between these resin films 41, 42, and the upper resin film 42 protrudes. The periphery is sealed to the lower resin film 41 which is kept horizontally while being curved on the coating flux 3.

In the embodiment shown in FIG. 13, the weir 110 for the flux 3 is provided by upward bending of the tip of the flat lead conductor. Occurrence can be eliminated. Therefore, similarly to the embodiment shown in FIG. 1, the bending stiffness (EI) of the thermal fuse body portion can be reduced to reduce the bending reaction force m acting on the thermal fuse body portion. The peeling force acting on the joint interface between the lead conductor and the fusible alloy piece can be reduced, and the stability of the joint interface can be enhanced.

も Also in the embodiment shown in FIG. 13, the thickness of the upper resin film 42 can be made smaller than the thickness of the lower resin film 41.

In the above description, if the upper end of each of the upwardly bent protrusions 110 of the lead conductor is provided with a radius, local damage to the upper resin film when the upper end is an edge, and local thinning due to a decrease in the surface tension of the coating resin. Can dispel concerns.

As shown in FIGS. 11 and 12, in addition to the one shown in FIG. 5, the resin-molded type thermal fuse according to the present invention has one end of a fusible alloy welded to the front surface of an upwardly bent convex portion of the lead conductor tip by welding or the like. It can also be implemented by providing a resin coating layer, for example, an epoxy resin coating layer, which is connected and surrounds the fusible alloy pieces and the flux and the end portions of the lead conductors.

(4) In the present invention, the width of the thermal fuse body can be made smaller than the width of the lead conductor portion outside the thermal fuse body. In addition, it is desirable to increase the margin for sealing the resin films and the margin for sealing the insulating cover plate to the insulating substrate as much as possible at both ends of the width of the thermal fuse body. In this case, as shown in FIG. 14A, the width w1 of the lead conductor portion inside the thermal fuse body can be made smaller than the width w2 of the lead conductor portion outside the thermal fuse body.

In the present invention, in order to adhere the flux, the flux is heated and melted and adhered to the outer surface including the fusible alloy piece, and the adhered flux is cast to the weir under the action of surface tension and interfacial tension. And solidify by natural cooling. In this case, the width of the lead conductor portion inside the thermal fuse body is made wider than the width of the fusible alloy piece, so that the width of the protrusion as a weir to the flux is made wider than the width of the fusible alloy piece. The flux having a width including one width is favorably blocked by the convex portion.

The flat lead conductor only needs to have a flat lead conductor portion inside the thermal fuse body. The entire flat conductor is flat, and as shown in FIG. 14A, the width of the inner conductor portion is w1, and the width of the outer conductor portion is w1. The width w2, w1 <w2, w1 = w2 as shown in (b) of FIG. 14, and w1> w2 as shown in (c) of FIG. As shown in FIG. 14 (d), a material in which the first half of a round wire is rolled and the rolled portion is used as an inner lead conductor portion can also be used. The same applies to the case where the convex portion 11 is provided by bending.
The upwardly bent convex portion 110 of the flat lead conductor tip may be subjected to additional processing as long as it can connect one end of the fusible alloy and can serve as a weir for the flux. For example, FIG. A horizontal key portion 1101 as shown in FIG. 14E and a folded portion 1102 as shown in FIG. 14F can also be added.
The bent convex portion 11 is usually a triangular convex portion as shown in FIG. 14 (g), but a rectangular convex portion as shown in FIG. 14 (h). It may be a trapezoidal convex part.
In addition, as shown in FIG. 14 (N), it is also possible to use one provided with a convex portion 1100 by cut-out bending.

In the present invention, when the maximum height of the coating flux is higher than the height of the bending protrusion or the upward bending protrusion of the flat lead conductor tip, the adhesive is pressed in a state where the coating flux is crushed by pressing an insulating cover plate. Sealing can be performed. Alternatively, during the sealing operation, the insulating cover plate can be continuously pressed, and the sealing with the adhesive can be performed while pressing the insulating cover plate.
The interface between the insulating substrate and the lead conductor can be sealed by bonding the interface with an adhesive or by filling the corner at the boundary between the end surface of the insulating substrate and the upper surface of the lead conductor with an adhesive.

ＣｕCu, Fe or the like can be used for the lead conductor, but it is preferable to use Ni, which is easy to weld, especially spot resistance weld. In order to facilitate welding with a fusible alloy piece and welding with an electrode, at least the tip of the lead conductor is mainly made of Sn, Cu, Ag, or Au, or a metal of these metals. It is preferable to coat an alloy as a component. In particular, in the case of a Ni lead conductor, when the electrode is fixed to the electrode by spot resistance welding, the Sn film thermally and stress-relaxes the thermal shock at the nugget, so that it is possible to guarantee the prevention of cracking of the ceramic insulating substrate. It is valid.

As the above upper resin film, lower resin film and auxiliary resin film, polyethylene terephthalate is preferable, but polyethylene naphthalate, polyamide, polyimide, polybutylene terephthalate, polyphenylene oxide, polyethylene sulfide Engineering plastics, such as polysulfone, engineering plastics such as polyacetal, polycarbonate, polyphenylene sulfide, polyoxybenzoyl, polyetheretherketone, and polyetherimide; and polypropylene, polyvinyl chloride, polyvinyl acetate, and polymethyl. Methacrylate, polyvinylidene chloride, polytetrafluoroethylene, ethylene polytetrafluoroethylene copolymer, ethylene vinyl acetate copolymer (EVA), AS resin, AB Resins, ionomer -, AAS resins, films of thermoplastic resins such as ACS resins can also be used.

As the above-mentioned insulating substrate and insulating cover plate, ceramics, particularly alumina ceramics plate, are preferable, but use of the above-mentioned thermoplastic resin plate, fiber reinforced epoxy resin plate, fiber reinforced phenol resin plate, insulating coated metal plate, etc. Is also possible.
As the insulating base and the insulating cover plate of the thermal fuse shown in FIGS. 8 and 9, a thermoplastic resin plate such as the polyethylene terephthalate described above can be suitably used.

The above-mentioned electrodes are formed by applying / baking a conductive paste such as an Ag paste, a Cu paste, an Au paste, a Pt paste, an Ag-Pt paste, an Ag-Pd paste, and printing / etching a metal foil of a metal foil laminated insulating substrate. It can also be formed.

As the fusible alloy piece, a round wire or a rolled wire can be used, and the width of the rolled wire can be made substantially equal to the width of the tip of the flat lead conductor.
The melting point of the fusible alloy piece is selected according to the protection temperature of the equipment. For batteries, an alloy with a solidus temperature of 80 to 120 ° C and a liquidus temperature of 90 to 120 ° C is used. Is done. For example, an alloy of 50 to 55% of In, 25 to 40% of Sn, and the balance of Bi, an alloy of 30 to 75% of In, 5 to 50% of Sn, and 0.5 to 25% of Cd, and further, the alloy composition of Cu, Ag, Au, Al, Bi Alloys containing one or more of them in total of 0.1 to 5%, Bi 48 to 53%, Pb 28 to 33%, Sn 13 to 19% alloys, In 0.5 to 4%, Bi 50 to 54%, Pb30 To 34% and Sn 14 to 18%.
The fusible alloy piece can be manufactured by casting or extruding a base material to obtain a rod, drawing the rod, and further rolling by a drawing method or a drawing rolling method. In addition, a rotating liquid spinning method is used, in which the cooling liquid in the drum is formed into a layer by rotating the drum, and a jet of molten alloy from a nozzle is injected into this rotating liquid layer at the same speed as its rotational speed to cool and solidify. You can also.

Recently, it has been required to use a composition that does not contain harmful metals in biological systems such as Pb and Cd from the viewpoint of environmental health as a fusible alloy piece. The composition that can be formed by the spinning method is [A] (1) 43% <Sn ≦ 70%, 0.5% ≦ In ≦ 10%, residual Bi, (2) 25% ≦ Sn ≦ 40%, 50 % ≦ In ≦ 55%, residual Bi, (3) 25% <Sn ≦ 44%, 55% <In ≦ 74%, 1% ≦ Bi <20%, (4) 46% <Sn ≦ 70%, 18% ≦ In <48%, 1% ≦ Bi ≦ 12%, (5) 5% ≦ Sn ≦ 28%, 15% ≦ In <37%, residual Bi (however, Bi57.5%, In25.2%, Sn17. Bi ± 2%, In and Sn ± 1% based on 3%, Bi 54%, In 29.7% and Sn 16.3%, respectively. (6) 10% ≦ Sn ≦ 18%, 37% ≦ In ≦ 43%, remaining Bi, (7) 25% <Sn ≦ 60%, 20% ≦ In <50%, 12% <Bi ≦ 33%, (8) One or more of Ag, Au, Cu, Ni, Pd, Pt, Sb, Ga, Ge, and P are added to 100 parts by weight of any of (1) to (7) in a total amount of 0.1%. (9) 33% ≦ Sn ≦ 43%, 0.5% ≦ In ≦ 10%, residual Bi, (10) 47% ≦ Sn ≦ 49%, 51% ≦ In ≦ 53% Add 3-5 parts by weight of Bi to 100 parts by weight, (11) 40% ≦ Sn ≦ 46%, 7% ≦ Bi ≦ 12%, residual In, (12) 0.3% ≦ Sn ≦ 1.5% , 51% ≦ In ≦ 54%, residual Bi, (13) 2.5% ≦ Sn ≦ 10%, 25% ≦ Bi ≦ 35%, residual In, (14) Any one of (9) to (13) 100 Heavy Part, one or more of Ag, Au, Cu, Ni, Pd, Pt, Sb, Ga, Ge, and P in a total amount of 0.01 to 7 parts by weight, (15) 10% ≦ Sn ≦ 25%, 48% ≦ In ≦ 60%, with 100% by weight of the remaining Bi being one or more of Ag, Au, Cu, Ni, Pd, Pt, Sb, Ga, Ge, and P in a total amount of 0.01 to 7 parts by weight. Composition of In-Sn-Bi alloy such as addition [B] (16) 30% ≦ Sn ≦ 70%, 0.3% ≦ Sb ≦ 20%, balance Bi, 100 parts by weight of (17) (16) One or two or more of Ag, Au, Cu, Ni, Pd, Pt, Ga, Ge and P are added in a total amount of 0.01 to 7 parts by weight. (18) 52% ≦ In ≦ 85%, residual Sn, (19) Ag, Au, Cu, Ni, Pd, Pt, Sb in 100 parts by weight of (18) One or more of Ga, Ge, and P are added in a total amount of 0.01 to 7 parts by weight. In-Sn based alloy composition [D] (20) 45% ≦ Bi ≦ 55%, remaining In, ( 21) One or more of Ag, Au, Cu, Ni, Pd, Pt, Sb, Ga, Ge and P are added to 100 parts by weight of the composition of (20) in a total amount of 0.01 to 7 parts by weight, etc. Ag, Au, Cu, Ni, Pd, Pt, Ga in 100 parts by weight of [E] (22) 50% <Bi ≦ 56%, balance Sn, (23) (22) One or two or more of Ge, P, and a total of 0.01 to 7 parts by weight are added. Au, Bi, Cu, Ni is added to 100 parts by weight of the composition [F] (24) In of the Bi-Sn based alloy. , Pd, Pt, Ga, Ge, P or a total of 0.01 to 7 parts by weight of a total of (25) 90% ≦ In ≦ 99.9% , 0.1% ≦ Ag ≦ 10%, 100% by weight of Au, Bi, Cu, Ni, Pd, Pt, Ga, Ge, P or more in total of 0.01 to 7 parts by weight (26) One or two of Au, Bi, Cu, Ni, Pd, Pt, Ga, Ge, and P are added to 100 parts by weight of 95% ≦ In ≦ 99.9%, 0.1% ≦ Sb ≦ 5%. There may be mentioned the composition of an In-based alloy in which 0.01 to 7 parts by weight of a total of the species or more are added, and from these, it is preferable to select a composition having a melting point suitable for the operating temperature of the thermal fuse.

The above flux includes natural rosin, modified rosin (hydrogenated rosin, disproportionated rosin, polymerized rosin, etc.) and these purified rosins, and organic acids such as hydrochloride of diethylamine, hydrobromide of diethylamine, adipic acid, etc. Can be used.

通常 Epoxy resin is usually used as the adhesive, but a curable resin such as phenol resin or polyurethane can also be used.

The dimensions of the insulating base are usually 5.0 to 15.0 mm on the long side, 2.0 to 4.0 mm on the short side, and 0.2 to 0.5 mm in thickness.
The dimensions of the insulating cover plate are usually such that the long side is 3.0 to 12.0 mm, the short side is 1.5 to 3.0 mm, and the thickness is 0.2 to 0.5 mm.
The dimensions of the lower resin film, the upper resin film and the auxiliary resin film are usually such that the long side is 5.0 to 15.0 mm and the short side is 3.0 to 5.0 mm. The thickness of the lower resin film is set to 0.2 to 0.4 mm, and the thickness of the upper resin film is equal to the thickness of the lower resin film or is reduced by 50 μm to 80 μm.
The dimensions of the lead conductor are generally such that the width of the outer portion is 2.0 to 4.0 mm and the width of the inner portion is 1.0 to 3.0 mm. The thickness of the lead conductor is 0.15 to 0.3 mm for the substrate type, and 0.07 to 0.15 mm for the film type or the resin mold type.

温度 The thermal fuse according to the present invention can be used for a secondary battery. For example, as shown in FIG. 16, the secondary battery pack can be mounted on a side surface of a flat case and inserted in series between a battery and a load. Therefore, when an abnormality occurs in the battery and the fusible alloy piece of the thermal fuse reaches its melting point temperature, for example, a predetermined temperature in the range of 80 ° C. to 100 ° C. due to heat generation of the battery, the fusible alloy piece is melted and the battery and the load are disconnected. Is electrically cut off, and the subsequent temperature rise of the battery is stopped. Therefore, abnormal heat generation of the battery can be prevented.

In the above, when the Joule heat of the fusible alloy piece can be ignored, the temperature Tx of the fusible alloy piece when the battery reaches the allowable temperature Tm becomes lower by 2 ° C. to 3 ° C. than Tm, and the melting point of the fusible alloy piece May be set to [Tm− (2 ° C. to 3 ° C.)].
However, when the Joule heat generation of the fusible alloy piece cannot be ignored, if the electric resistance of the fusible alloy piece is R, the conduction current is I, and the thermal resistance between the device and the fuse element is H,

Tx = Tm− (2 ° C. to 3 ° C.) + HRI ²

Holds, and it is effective to set the melting point of the fusible alloy piece based on the above equation.

In the thermal fuse according to the present invention, a current-carrying heating element is provided, and a film resistor is provided by, for example, applying and baking a resistive paste (for example, a paste of a metal oxide powder such as ruthenium oxide). A precursor, for example, an abnormal rise in the battery voltage at the time of overcharging is detected, and the detection signal is applied to the film resistor to generate heat, and the heat is generated to melt the fusible alloy piece.
For example, the above-mentioned film resistance is provided on the upper surface of an insulating base, a heat-resistant and heat-conductive insulating film, for example, a glass-baked film is formed thereon, a pair of electrodes is further provided, and an upwardly bent convex portion is provided at the tip. A flat lead conductor is connected to each electrode, a fusible alloy piece is connected between both electrodes, a flux is coated from the fusible alloy piece to the tip convex portion of the lead conductor, and an insulating cover plate is placed on the insulating base. The insulating cover plate can be disposed and sealed around the insulating cover plate to the insulating base with an adhesive.

FIG. 15 is a circuit diagram showing a use state of a thermal fuse with a heating element, where P is a thermal fuse, 2 is a fusible alloy piece, R is a resistor, IC is an abnormal voltage detection energizing circuit, and D is a Zener. A diode, Tr indicates a transistor, E indicates a battery, and S indicates a charger. When the battery voltage increases due to overcharging, the Zener diode D is turned on and the transistor Tr is turned on, and a current flows through the resistor R. The fusible alloy piece 2 is blown off by the heat generated by the current flowing through the resistor R. The abnormal voltage detection energizing circuit is formed on a circuit board mounted on the battery pack.

2 is a film type thin fuse having a configuration shown in FIG. 1. As the lower resin film 41 and the upper resin film 42, a polyethylene terephthalate film having a long side of 7.3 mm, a short side of 3.4 mm, and a thickness of 188 μm was used. The flat lead conductor 1 has a thickness of 100 μm, a distance of 2.3 mm from the tip of the lead conductor to the bent protrusion 11, a height of the protrusion 11 of 0.50 mm, an inner width of 2.6 mm, and an outer width of 3.5 mm. A Ni conductor coated with a Cu film at the tip was used, and the distance between the lead conductors was 0.8 mm. For the fusible alloy piece 2, a round wire having a composition of In52% -Sn36% -Bi12%, a diameter of 0.3 mm and a length of 4.4 mm is used, and the flux 3 mainly composed of rosin is used. The heated and melted product was cast between the protruding portions 11 of the lead conductors 1 and 1 and solidified by cooling.
Sealing of the films was performed by ultrasonic welding, and fusion between the lead conductor and the film was performed by electromagnetic induction heating under pressure of a ceramic chip.

[Comparative Example 1]
An attempt was made to form a convex portion by punching instead of bending the convex portion of the lead conductor in Example 1. However, a crack was generated in the lead conductor having a thickness of 100 μm. (The height was the same as the height of the bent protrusion of Example 1). Except for this, it was the same as Example 1.

When the number of samples in each of Example 1 and Comparative Example 1 was 50, the resistance between the lead conductors was measured, and the standard deviation was calculated to evaluate the degree of dispersion. It became clear that it was significantly smaller than
From these results, the embodiment and the comparative example are common in that a weir is provided in order to increase the flux thickness.However, in the embodiment, the thickness of the lead conductor can be reduced, and this occurs due to the curved sealing of the upper resin film. Since it is possible to reduce the burden of the bending reaction force on the lead conductor, it can be confirmed that the bonding interface between the lead conductor and the fusible alloy piece can be stably maintained, and the resistance value of the interface can be maintained stably.

同 じ Same as Example 1 except that the thickness of the upper resin film was reduced to 125 μm to make it thinner.

The resistance value between the lead conductors was measured with the number of each sample of Example 2 being 50, the standard deviation was calculated, and the degree of dispersion was evaluated. There was found.
This result is because the warpage generated due to the curved sealing of the upper resin film could be made smaller than in Example 1, and the interface resistance value was further stabilized by stabilizing the bonding interface between the lead conductor and the fusible alloy piece. Maintenance can be expected.

3 is a film type thin fuse having a configuration shown in FIG. 2. A polyethylene terephthalate film having a long side of 7.3 mm, a short side of 3.4 mm and a thickness of 188 μm is used for the lower resin film 41, and a 125 μm thick polyethylene having the same outer shell as the lower resin film is used for the upper resin film 42. A terephthalate film was used. The flat lead conductor 1 has a thickness of 100 μm, a flat surface 101 on the lower resin film surface, a distance from the lead conductor tip to the bent protrusion 11 of 2.3 mm, a height of the protrusion 11 of 0.6 mm, and an inner side. A Ni conductor having a width of 2.6 mm, an outer width of 3.5 mm, and a Cu film coated on the front end including the exposed portion was used, and the distance between both ends of the lead conductor was 0.8 mm. For the fusible alloy piece 2, a round wire having a composition of In52% -Sn36% -Bi12%, a diameter of 0.3 mm and a length of 4.4 mm is used, and the flux 3 mainly composed of rosin is used. Then, the heat-fused flux was cast between the projections 11 of the two lead conductors, and was cooled and solidified.
The interface between the lead conductor and the lower resin film was thermally welded, and the films were sealed by ultrasonic welding.

The resistance value between the lead conductors was measured with 50 samples in Example 3, and the standard deviation was calculated to evaluate the degree of dispersion. As a result, it was found that the dispersion was equivalent to the variation in resistance value in Example 2. did.

6 is a resin mold type thin fuse having a configuration shown in FIG. 5. The flat lead conductor 1 has a thickness of 100 μm, a distance of 2.3 mm from the tip of the lead conductor to the bent protrusion 11, a height of the protrusion 11 of 0.50 mm, an inner width of 2.6 mm, and an outer width of 3.5 mm. A Ni conductor coated with a Cu film at the tip was used, and the distance between the lead conductors was 0.8 mm. For the fusible alloy piece 2, a round wire having a composition of In52% -Sn36% -Bi12%, a diameter of 0.3 mm and a length of 4.4 mm is used. The used and melted flux was cast between the protruding portions 11 of the two lead conductors, and was cooled and solidified.
The resin mold coating layer 40 was provided by dip coating of a room temperature-cured epoxy resin liquid.

[Comparative Example 2]
An attempt was made to form a convex portion by punching instead of bending the convex portion of the lead conductor in Example 4. However, a crack was generated in the lead conductor having a thickness of 100 μm. (The height was the same as the height of the bent convex portion in Example 4). Except for this, it was the same as Example 4.

After performing a predetermined heat cycle test with 50 samples in each of Example 4 and Comparative Example 2, the resistance value between the lead conductors was measured, the standard deviation was calculated, and the degree of dispersion was evaluated. It was found that the variation in the resistance value was significantly smaller than that in Comparative Example 2.
From this result, it is common in Example 4 and Comparative Example 2 that a weir is provided to increase the flux thickness. However, in Example 4, the thickness of the lead conductor can be reduced, and the bending generated based on the heat cycle can be achieved. Since the amount of the moment acting on the lead conductor can be reduced, it can be confirmed that the joint interface between the lead conductor and the fusible alloy piece can be stably maintained, and the resistance value of the interface can be stably maintained.

基板 A board type thin fuse having the configuration shown in FIG. As the insulating base 51, a rectangular alumina ceramic plate having a long side of 7.0 mm, a short side of 2.6 mm, and a thickness of 0.3 mm was used. The electrode 6 was formed by applying and baking an Ag paste, the long side was 2.8 mm, the short side was 1.8 mm, the thickness was 35 μm, and the electrode interval was 0.9 mm. As the flat lead conductor 1, a tin-plated Ni lead conductor having a width of 1.2 mm at the inner portion, a width of 3.0 mm at the outer portion, a thickness of 0.2 mm, and a height of the bent protrusion 110 at the tip of the lead conductor of 0.5 mm is used. did. For the fusible alloy piece 2, a rolled wire having a composition of In52% -Sn36% -Bi12%, a long side of 2.5 mm, a short side of 0.85 mm, and a thickness of 0.23 mm is used. The distance from the conductor tip was 1.2 mm. A flux containing rosin as a main component was used as the flux 3, and was heated and melted to adhere over the entire length of the fusible alloy piece, the electrode, and the tip of the lead conductor. A rectangular alumina ceramic plate having a long side of 4.5 mm, a short side of 1.6 mm, and a thickness of 0.2 mm is used for the insulating cover plate 52, and the periphery of the insulating cover plate 52 is formed of an epoxy resin on the insulating base 51 and the flat lead conductor 1. It was sealed with an adhesive 7, and the space between the lead conductor and the end face of the insulating substrate was sealed with the same epoxy resin adhesive.

[Comparative Example 3]
In contrast to the fifth embodiment, instead of the upwardly bent protruding portion of the lead conductor tip, a projection having a height of 0.5 mm is formed by punching at a position 0.6 mm from the tip of the lead conductor. The spacing was 0.6 mm. Other than this, it was the same as Example 5.

The number of samples in each of Example 5 and Comparative Example 3 was 30, and the sample was immersed in silicon oil under a current of 0.1 amperes, and the temperature of the silicon oil was raised at a rate of 1 ° C. per minute, and the sample was split. When the silicon oil temperature was measured, the temperature was 93.0 to 95.9 ° C. in Example 5, but was 93.0 to 98.0 ° C. in Comparative Example 3.
This result indicates that, in Comparative Example 3, the inclination of the insulating cover plate with respect to the insulating substrate was unavoidable, the space space for the spheroidization of the molten fusible alloy piece was not constant, and the spheroidization variability was large. On the other hand, in the fifth embodiment, the insulating cover plate can be held without inclination by the upwardly-bent convex portion having a predetermined width at both ends of the lead conductors, and the uniformity of the spatial space with respect to the spheroidization of the molten fusible alloy piece is improved. Can be guaranteed, and the dispersion of the divided spheroids can be sufficiently reduced.

薄型 A thin fuse having the configuration shown in FIG. As the insulating base 51, a polyethylene terephthalate plate having a long side of 7.0 mm, a short side of 2.6 mm, and a thickness of 0.5 mm was used. The flat lead conductor 1 has an inner portion having a width of 1.2 mm, an outer portion having a width of 3.0 mm, a thickness of 0.2 mm, and a bent protrusion having a height of 0.5 mm over the entire width at a distance of 1.2 mm from the tip of the lead conductor. A portion 11 was provided, and a Ni lead conductor plated with Ag was used at the tip, and was embedded under heating on the surface of the insulating substrate 51 so that the interval between the lead conductors 1 and 1 was 0.9 mm. As the fusible alloy piece 2, a rolled wire having a composition of In52% -Sn36% -Bi12%, a long side of 2.5 mm, a short side of 0.85 mm, and a thickness of 0.23 mm was used. The flux 3 was mainly composed of rosin, and was heated and melted, cast between the projections 11 of the two lead conductors, and solidified by cooling. For the insulating cover plate 52, a 0.5 mm thick polyethylene terephthalate plate having the same outer dimensions as the insulating substrate 51 and having a 0.3 mm convex line around the lower surface is used, and a gap between the convex line and the insulating substrate is used. Sealed with epoxy resin adhesive.

[Comparative Example 4]
In contrast to Example 6, instead of the bent convex portion 11 having a height of 0.5 mm, a convex portion having a width of 0.7 mm and a height of 0.5 mm was formed by punching. Except for this, it was the same as Example 6.

The number of samples in each of Example 6 and Comparative Example 4 was 30. The sample was immersed in silicon oil under a current of 0.1 amperes, and the temperature of the silicon oil was raised at a rate of 1 ° C. per minute, and the sample was split. When the silicon oil temperature at that time was measured, it was 93.0 to 95.9 ° C. in Example 6, but was 93.0 to 98.1 ° C. in Comparative Example 4.
This result indicates that, in Comparative Example 4, the inclination of the insulating cover plate with respect to the insulating base was inevitable, the spatial space for the spheroidization of the molten fusible alloy piece was not constant, and the spheroidization variation was large. On the other hand, in Example 6, the insulating cover plate can be held by the bent convex portion with a predetermined width of both lead conductors without inclination, and the uniformity of the space for the spheroidization of the molten fusible alloy piece is assured. It can be presumed that the dispersion of the divided spheroids can be sufficiently reduced.

It is a board-resin mold type thin fuse having the configuration shown in FIG. As the insulating base 51, a rectangular alumina ceramic plate having a long side of 7.0 mm, a short side of 2.6 mm, and a thickness of 0.3 mm was used. The electrode 6 was formed by applying and baking an Ag paste, having a long side of 2.8 mm, a short side of 1.8 mm, a thickness of 35 μm, and an electrode interval of 0.9 mm. For the flat lead conductor 1, a tin-plated Ni lead conductor having a width of 1.2 mm at the inner portion, a width of 3.0 mm at the outer portion, a thickness of 0.2 mm, and a height of 0.5 mm at the bent convex portion 110 at the tip of the lead conductor is used. used. The fusible alloy piece 2 has a composition of In52% -Sn36% -Bi12%, and uses a rolled wire having a long side of 2.5 mm, a short side of 0.85 mm, and a thickness of 0.23 mm. The distance from the tip was 1.2 mm. A flux containing rosin as a main component was used as the flux 3, and was heated and melted and cast and attached over the entire length of the fusible alloy piece, the electrode, and the tip of the lead conductor.
The resin mold coating layer 53 was provided by drop coating of a cold-setting epoxy resin liquid.

[Comparative Example 5]
Example 7 was the same as Example 7 except that the upwardly bent convex portion of the lead conductor tip was omitted.

The number of samples in each of Example 7 and Comparative Example 5 was 30. The sample was immersed in silicon oil under a current of 0.1 amperes, and the temperature of the silicon oil was raised at a rate of 1 ° C. per minute, and the sample was split. When the temperature of the silicone oil was measured, the operation delay was considerably delayed in Comparative Example 5 as compared with Example 7.
This result indicates that, in Example 7, the flux was allowed to adhere to the vicinity of the fusible alloy piece in a sufficient amount by using the upwardly bent protruding portion of the lead conductor tip as a weir, and the molten alloy was quickly divided and spheroidized on both sides. On the other hand, in Comparative Example 5, it can be presumed that rapid spheroidization of the molten alloy to both sides of the molten alloy is difficult to guarantee due to insufficient flux.

The above-mentioned thermal fuse can also be used as a thin current fuse that cuts off the fusible alloy piece by self-heating due to energization and interrupts energization.

3 is a view illustrating an embodiment of a thermal fuse according to the present invention. It is a drawing showing another embodiment of the thermal fuse according to the present invention. It is a drawing showing another embodiment of the thermal fuse according to the present invention. It is a drawing showing another embodiment of the thermal fuse according to the present invention. It is a drawing showing another embodiment of the thermal fuse according to the present invention. It is a drawing showing another embodiment of the thermal fuse according to the present invention. It is a drawing showing another embodiment of the thermal fuse according to the present invention. It is a drawing showing another embodiment of the thermal fuse according to the present invention. It is a drawing showing another embodiment of the thermal fuse according to the present invention. It is a drawing showing another embodiment of the thermal fuse according to the present invention. It is a drawing which shows the principal part of another Example of the thermal fuse which concerns on this invention from the above. It is a drawing which shows the principal part of another Example of the thermal fuse which concerns on this invention from the above. It is a drawing showing another embodiment of the thermal fuse according to the present invention. It is a drawing showing many examples of different flat lead conductors used in the present invention. FIG. 4 is a circuit diagram showing an operation mechanism of an embodiment with a heating element in the thermal fuse according to the present invention. 3 is a view illustrating a battery pack to which a thermal fuse according to the present invention is mounted. 1 is a drawing showing an example of a conventional thin thermal fuse. It is a drawing which shows another example of the above-mentioned conventional thin thermal fuse. It is a drawing which shows another example of the above-mentioned conventional thin thermal fuse. It is a drawing which shows another example of the above-mentioned conventional thin thermal fuse. 4 is a view showing a shape of a flux of a conventional thin thermal fuse. 6 is a diagram used to explain a problem of a conventional thermal fuse.

Explanation of reference numerals

REFERENCE SIGNS LIST 1 flat lead conductor 11 bent protrusion 110 upward bent protrusion 2 fusible alloy piece 3 flux 41 lower resin film 42 upper resin film 43 auxiliary film 51 insulating base 52 insulating cover 53 watertight resin coating 6 electrode 7 adhesive

Claims (19)

The fusible alloy piece is connected between the flat lead conductors in a state where the thickness center of the fusible alloy piece is located above the thickness center of the flat lead conductor, and flux is applied to the fusible alloy piece and the lead conductor portion in the vicinity thereof. These are covered with a lower resin film and an upper resin film, and the lead conductor is air-tightly drawn out and sealed, and the upper resin film is bent on the protruding contents on the inner surface side. A thin thermal fuse, wherein a bent convex portion is provided on a lead conductor portion between one end of a molten alloy and a film sealing portion, and the convex portion serves as a weir for application of the flux. A pair of flat lead conductor ends are fixed to the lower surface of the lower resin film, and a portion separated by a predetermined distance from the tip of each lead conductor is bulged to appear on the upper surface of the film. The fusible alloy piece is connected between the portions, the fusible alloy piece and a portion of the exposed portion near the fusible alloy piece end are coated with flux, and the upper resin film is sealed around the lower resin film. In addition, in the thermal fuse in which the upper resin film is curved on the projecting contents on the inner surface side, a convex portion is provided in the vicinity of one end of the fusible alloy at the lead conductor exposed portion, and the convex portion is formed of the flux. A thin thermal fuse characterized by being a weir for coating. A pair of flat lead conductor ends is fixed to the lower surface of the lower resin film, and a portion separated by a predetermined distance from the tip of each lead conductor has a predetermined width and a land portion substantially flush with the upper surface of the film. And a bent convex portion on the rear end side of the land portion is bent and exposed on the upper surface of the film, and a fusible alloy piece is connected between the exposed land portions, and the fusible alloy piece and the Flux is applied to almost the entire land portion using the bent convex portion as a weir, the upper resin film is sealed around the lower resin film, and the upper resin film is formed on the protruding contents on the inner surface thereof. A thin thermal fuse characterized by being curved and having an auxiliary resin film adhered to a lower surface of a lower resin film. The thin thermal fuse according to claim 1, wherein the upper resin film is thinner than the lower resin film. The temperature at which the fusible alloy piece is connected between the flat lead conductors, the flux is attached to the fusible alloy piece and the lead conductor at a predetermined distance from one end of the fusible alloy piece, and the resin layer is coated surrounding these. A thin thermal fuse, wherein a bent convex portion is provided on a lead conductor portion at a predetermined distance from one end of a fusible alloy, and the convex portion serves as a weir for application of the flux. The thin thermal fuse according to any one of claims 1 to 5, wherein a radius is provided at upper ends on both sides of the bent convex portion. A pair of electrodes are provided on the insulating base, a flat lead conductor is connected to each electrode, a fusible alloy piece is connected between these electrodes, and the fusible alloy piece and the fusible alloy piece end to the flat lead conductor tip end. In a thermal fuse to which a flux is attached and a watertight insulating cover is provided on the insulating base, a bent convex portion is provided at a flat lead conductor portion at a predetermined distance from the tip of the flat lead conductor or a fusible alloy piece. A thin thermal fuse, wherein the convex portion serves as a weir against the application of the flux. The thin thermal fuse according to claim 7, wherein one end of the fusible alloy is also connected to the flat lead conductor. A pair of flat lead conductors are provided on the insulating base, a fusible alloy piece is connected between these flat lead conductors, and flux is attached from the fusible alloy piece and one end of the fusible alloy to the flat lead conductor tip. In a thermal fuse in which a water-tight insulating cover is provided on an insulating substrate, a bent convex portion is provided on a flat lead conductor portion at a predetermined distance from the tip of the flat lead conductor or a fusible alloy piece, and the convex portion is A thin thermal fuse characterized by being a weir against flux application. The thin type according to any one of claims 7 to 9, wherein the water-tight insulating cover is constituted by a cover plate in contact with the bent projections of both flat lead conductors, and an adhesive sealing the periphery of the cover plate to an insulating base. Thermal fuse. The fusible alloy piece is connected between the flat lead conductors in a state where the thickness center of the fusible alloy piece is located above the thickness center of the flat lead conductor, and flux is applied to the fusible alloy piece and the lead conductor portion in the vicinity thereof. In a thermal fuse in which the lead conductor is airtightly led out and sealed by a lower resin film and an upper resin film, and the upper resin film is curved on a protruding content on the inner surface side thereof, A thin thermal fuse, wherein a bent convex portion is provided at the tip of a lead conductor, one end of a fusible alloy is connected to the front surface of the convex portion, and the convex portion serves as a weir for application of the flux. The thin thermal fuse according to any one of claims 7 to 11, wherein the upper end of each side of the projection is rounded. 13. The thin thermal fuse according to claim 11, wherein the upper resin film is thinner than the lower resin film. The thin thermal fuse according to any one of claims 1 to 13, wherein a conductor in which a width of a lead conductor portion in the thermal fuse body is wider than a width of the fusible alloy piece is used as the flat lead conductor. 15. The thin thermal fuse according to claim 14, wherein a lead conductor portion in the thermal fuse body is formed by rolling. The thin thermal fuse according to any one of claims 1 to 15, wherein the lead conductor is made of Ni, and at least a tip portion is coated with one of Sn, Cu, Ag, and Au, or an alloy containing these as main components. 17. The thin thermal fuse according to claim 1, further comprising a heating element for fusing the fusible alloy piece. The fusible alloy piece is any one of an In-Sn-Bi-based alloy, a Bi-Sn-Sb-based alloy, an In-Sn-based alloy, an In-Bi-based alloy, a Bi-Sn-based alloy, and an In-based alloy. The composition of the Sn—Bi alloy is (1) 43% <Sn ≦ 70%, 0.5% ≦ In ≦ 10%, remaining Bi, (2) 25% ≦ Sn ≦ 40%, 50% ≦ In ≦ 55% (3) 25% <Sn ≦ 44%, 55% <In ≦ 74%, 1% ≦ Bi <20%, (4) 46% <Sn ≦ 70%, 18% ≦ In <48%, 1% ≦ Bi ≦ 12%, (5) 5% ≦ Sn ≦ 28%, 15% ≦ In <37%, remaining Bi (however, Bi57.5%, In25.2%, Sn17.3% and Bi54%, (Excluding the ranges of Bi ± 2%, In and Sn ± 1% based on In29.7% and Sn16.3%), (6) 10% ≦ Sn ≦ 18 %, 37% ≦ In ≦ 43%, residual Bi, (7) 25% <Sn ≦ 60%, 20% ≦ In <50%, 12% <Bi ≦ 33%, (8) (1) to (7) To 100 parts by weight of any one of Ag, Au, Cu, Ni, Pd, Pt, Sb, Ga, Ge, and P, in a total amount of 0.01 to 7 parts by weight, (9) 33% ≦ Sn ≦ 43%, 0.5% ≦ In ≦ 10%, residual Bi, (10) Add 3 to 5 parts by weight of Bi to 100 parts by weight of 47% ≦ Sn ≦ 49%, 51% ≦ In ≦ 53%. (11) 40% ≦ Sn ≦ 46%, 7% ≦ Bi ≦ 12%, remaining In, (12) 0.3% ≦ Sn ≦ 1.5%, 51% ≦ In ≦ 54%, remaining Bi, ( 13) 2.5% ≦ Sn ≦ 10%, 25% ≦ Bi ≦ 35%, residual In, (14) Ag, Au, Cu, Ni, Pd, 100 parts by weight of any of (9) to (13) One or more of t, Sb, Ga, Ge, and P are added in a total amount of 0.01 to 7 parts by weight, (15) 10% ≦ Sn ≦ 25%, 48% ≦ In ≦ 60%, and the remaining Bi is 100. A total of 0.01 to 7 parts by weight of one or more of Ag, Au, Cu, Ni, Pd, Pt, Sb, Ga, Ge, and P is added to parts by weight, and the composition of the Bi-Sn-Sb-based alloy is (16) 30% ≦ Sn ≦ 70%, 0.3% ≦ Sb ≦ 20%, residual Bi, (17) Ag, Au, Cu, Ni, Pd, Pt, Ga, Ge in 100 parts by weight of (16) , P is added in an amount of 0.01 to 7 parts by weight in total, and the composition of the In—Sn alloy is (18) 52% ≦ In ≦ 85%, the remaining Sn is (100) of (19) and (18). One part or two or more of Ag, Au, Cu, Ni, Pd, Pt, Sb, Ga, Ge, and P are added in a weight part in a total of 0.01 to 0.01%. By weight, Ag, Au, Cu, Ni, Pd, Pt are added to 100 parts by weight of the composition of (20) 45% ≦ Bi ≦ 55%, the balance of In, (21) and (20). , Sb, Ga, Ge, P, or a total of 0.01 to 7 parts by weight of a Bi-Sn based alloy having a composition of (22) 50% <Bi ≦ 56%, residual Sn, (23) ) (22) 100 parts by weight of Ag, Au, Cu, Ni, Pd, Pt, Ga, Ge, P or a total of 0.01 to 7 parts by weight, and the composition of the In-based alloy is (24) A total of 0.01 to 7 parts by weight of one or more of Au, Bi, Cu, Ni, Pd, Pt, Ga, Ge, and P is added to 100 parts by weight of In. (25) 90% ≦ In 100 parts by weight of In ≦ 99.9%, 0.1% ≦ Ag ≦ 10%, Au, Bi, Cu, Ni, Pd, Pt, , Ga, Ge, P, one or more of 0.01 to 7 parts by weight in total, (26) 100 parts by weight of 95% ≦ In ≦ 99.9%, 0.1% ≦ Sb ≦ 5% 18. One or two or more of Au, Bi, Cu, Ni, Pd, Pt, Ga, Ge, and P are added in a total amount of 0.01 to 7 parts by weight. The thin thermal fuse according to any of the above. A thin current fuse, wherein the thin thermal fuse according to any one of claims 1 to 16 is used as a current fuse.

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