JP5867043B2 - Thermal fuse and manufacturing method thereof - Google Patents

Description

  The present invention relates to a thermal fuse used for preventing equipment damage due to excessive temperature rise and a method for manufacturing the same.

  In recent years, with the development of mobile phones etc., lithium ion batteries are often used as secondary batteries, but there is an increased risk that the batteries will be damaged or explode due to heat generated by rapid discharge such as short circuit. . Therefore, in order to ensure the safety of the secondary battery, a thermal fuse is used. However, there is an increasing demand for downsizing and thinning the thermal fuse.

  Therefore, as shown in the cross-sectional view of the conventional thermal fuse of FIG. 5, a pair of terminal portions 2 made of a metal flat plate are attached on the base film 1, and the fusible body 3 is joined so as to bridge between the terminal portions 2. The cover film 5 containing the flux 4 is covered with the upper surface of the fusible body 3, and the cover film 5 and the base film 1 are sealed by ultrasonic welding so as to wrap the fusible body 3 with the cover film 5 and the base film 1. I got a fuse.

  As prior art document information related to the invention of this application, for example, Patent Document 1 is known.

Japanese Patent Laid-Open No. 2001-6508

  In the above-mentioned conventional thermal fuse, since the fusible body is soft, a force is applied to the fusible body through the flux when sealing by ultrasonic welding, and the fusible body may be deformed or cracked. It was. An object of the present invention is to provide a thermal fuse having stable performance by suppressing deformation of a fusible body.

In order to solve the above problems, the present invention provides a base film, an intermediate film provided on the base film, a pair of terminal portions provided between the base film and the intermediate film, and the pair of terminal portions. A thermal fuse comprising a fusible body joined by bridging and a cover film provided on the base film so as to cover the fusible body, and part of the intermediate film can be applied from both sides of the fusible body. It extends to the space between the base film and the soluble body toward the solution, and is configured so as to face the space .

  With the above configuration, when sealing is performed by ultrasonic welding, even if a force is applied from above the fusible body, the intermediate film is present below the force, so that deformation can be supported and suppressed. Furthermore, by extending from both sides of the fusible body toward the fusible body and facing each other, a space connecting the two terminal parts can be formed under the fusible body, and it is cut quickly when the fusible body melts with heat. Can be made.

The inside view top view of the thermal fuse in one embodiment of the present invention Sectional view of the AA line in FIG. The figure explaining the manufacturing method of the thermal fuse in one embodiment of this invention Top view of the inside of another thermal fuse in one embodiment of the present invention Cross section of conventional thermal fuse

  Hereinafter, a thermal fuse in an embodiment of the present invention will be described with reference to the drawings.

  FIG. 1 is a top view of an internal view of a thermal fuse in an embodiment of the present invention, and FIG. 2 is a cross-sectional view taken along line AA in FIG.

  1 and 2, a pair of terminal portions 13 made of an iron-nickel alloy plate and having a thickness of about 0.2 mm are linearly opposed to each other with a space therebetween, and are made of polyethylene naphthalate (hereinafter referred to as PEN). It is sandwiched and fixed between a base film 11 of about 0.18 mm and an intermediate film 12 made of PEN and having a thickness of about 0.12 mm.

  Further, a fusible body 14 made of an Sn—In—Bi alloy and having a fusing temperature of 86 to 101 ° C. is joined by laser welding while bridging between the terminal portions 13.

  At this time, the terminal portion 13 is fixed with an interval of about 0.7 mm, the thickness of the fusible body 14 is about 0.14 mm, and the width (vertical direction in FIG. 1) is about 0.9 mm. .

  A cover film 15 made of PEN is embossed on these, and is welded to the base film 11 and the intermediate film 12 at the film welded portion 18 so as to cover the fusible body 14, and the flux 16 is filled therein. ing.

  The interior view of FIG. 1 shows the inside of the cover film 15 cut out along the line B-B and the inside of the intermediate film 12 cut out along the line C-C. The cut-out interior of the film welded portion 18 is schematically shown because the films are integrated by welding.

  Here, the intermediate film 12 has a shape that covers a part of the terminal portion 13 as viewed from above and surrounds the entire region where the fusible body 14 is mounted.

  A part thereof was stretched from both sides of the fusible body 14 (from the upper and lower sides of the fusible body 14 in FIG. 1) toward the fusible body 14 between the terminal portions 13 and below the fusible body 14. A portion 19 is formed.

  The portions 19 extended from both sides are opposed to each other with a space 17 of 0.1 to 0.4 mm below the fusible body 14.

  In addition, the width | variety (width | variety of a horizontal direction in FIG. 1) of the part 19 extended | stretched from the both sides of the intermediate film 12 is about 0.4 mm.

  Under the fusible body 14 between the terminal portions 13, the portions 19 extended from both sides are arranged so as to face each other. Therefore, when the cover film 15 is welded, a force is applied from above the fusible body 14. Since there are portions 19 extending from both sides below, it can be a support and suppress deformation.

  Furthermore, when the space 17 is provided between the portions 19 extended from both sides so as to be opposed to each other, the flux 16 put in the space 17 also flows toward the space 17, so that the gap between the terminal portions 13 is located under the fusible body 14. A connecting space can be formed, and when the fusible body 14 is melted by heat, it can be quickly cut.

  Next, the manufacturing method of the thermal fuse in one Embodiment of this invention is demonstrated.

  First, as shown in FIG. 3A, on the base film 11 made of PEN and having a thickness of about 0.18 mm, a pair of terminal portions 13 are linearly arranged with an interval of about 0.7 mm. And the terminal film 13 is sandwiched between the base film 11 and the intermediate film 12 so that the intermediate film 12 made of PEN and having a thickness of about 0.12 mm is overlapped.

  At this time, the intermediate film 12 is formed in a shape that covers a part of the terminal portion 13 as viewed from above and surrounds the entire region where the fusible body 14 is mounted.

  And the part forms the part 19 extended | stretched from the both sides extended | stretched from the both sides of the soluble body 14 to the center direction, and the parts 19 extended | stretched from both sides oppose each other with the space 17 of about 0.5 mm. It is formed as follows.

  In addition, it is good to provide the through-hole 21 in the position where the base film 11 and the intermediate | middle film 12 oppose, A pilot pin (not shown) etc. can be inserted in the through-hole 21, and positioning can be performed reliably. In addition, the base film 11 and the intermediate film 12 are continuously formed in a tape shape and can be continuously produced, so that the production efficiency can be improved.

  Similarly, the through hole 21 may be provided in the cover film 15.

  Next, as shown in FIG. 3B, the terminal portion 13 sandwiched between the base film 11 and the intermediate film 12 is welded and fixed.

  As a method of welding, the terminal portion 13 may be heated by hot pressing or by passing an electric current through the terminal portion 13 and may be welded by the heat.

  At this time, the terminal welding part 20 of the part which overlaps with the terminal part 13 of the intermediate | middle film 12 is welded, pressing from the upper surface.

  By doing so, the intermediate film 12 melted in the terminal welded portion 20 becomes thin, and the intermediate film 12 other than the terminal welded portion 20 is deformed so as to be lowered downward, and the intermediate film 12 overlaps the base film 11. The part 19 extended | stretched from the both sides integral with the intermediate | middle film 12 also falls below, and enters between a pair of terminal parts 13, and the part 19 extended | stretched from both sides between the terminal parts 13 and a soluble body 14 can be arranged below.

  Next, as shown in FIG. 3C, the fusible body 14 is mounted so as to bridge between the terminal portions 13, and a part of the fusible body 14 is melted by a laser while applying a cooling plate (not shown). Thereby, the terminal part 13 and the soluble body 14 are joined.

  Next, as shown in FIG. 3 (d), the cover film 15 is mounted on the one shown in FIG. 3 (c).

  The cover film 15 is obtained by embossing a PEN film. In FIG. 3D, the cover film 15 is raised on the front side of the drawing and a concave portion is formed on the opposite side. Flux 16 is put in the embossed process. The flux 16 is melted and injected with a dispenser, and is softened when it is placed on the fusible body 14.

  Next, by applying an ultrasonic horn (not shown) and welding the base film 11, the intermediate film 12, and the cover film 15 at the film welded portion 18, as shown in FIG. The flux 16 is sealed.

  At this time, the part 19 extended from both sides of the fusible body 14 toward the fusible body 14 between the terminal portions 13 and under the fusible body 14 is further extended toward the center thereof.

  If the width of the space 17 is too small, the portions 19 extended from both sides collide with each other, and the fusible body 14 may be pushed up and the fusible body 14 may be deformed. In this embodiment, the space 17 before ultrasonic welding is about 0.5 mm, and after ultrasonic welding, it extends toward the center and is 0.1 to 0.4 mm.

  Thus, the amount of elongation due to ultrasonic welding is mainly influenced by the thickness of the intermediate film 12, and the size of the space 17 before ultrasonic welding is desirably set to be three times or more the thickness of the intermediate film 12.

  Finally, as shown in FIG. 3 (f), a thermal fuse can be obtained by cutting the film into pieces by ultrasonic welding.

  In FIG. 3, the opposing space 17 of the portion 19 extended from both sides of the intermediate film 12 is formed orthogonal to the extending direction, but obliquely crossed with respect to the extending direction as shown in FIG. 4. (In FIG. 4 as well, FIG. 4 shows an introspective view cut out along the lines BB and CC as in FIG. 1).

  In this case, even if the portions 19 extended from both sides collide with each other at the time of ultrasonic welding, since they are inclined with respect to the extending direction, they are deformed in the width direction (lateral direction in FIG. 4) Ultrasonic welding can be performed without deforming the solution 14.

  The thermal fuse according to the present invention has a stable characteristic and an excellent fusing property, and is industrially useful.

DESCRIPTION OF SYMBOLS 11 Base film 12 Intermediate | middle film 13 Terminal part 14 Soluble body 15 Cover film 16 Flux 17 Space 18 Film welding part 19 The part extended | stretched from both sides 20 Terminal welding part

Claims (4)

A base film, an intermediate film provided on the base film, a pair of terminal portions provided between the base film and the intermediate film, and a bridge between the pair of terminal portions. A thermal fuse comprising a fusible body and a cover film provided on the base film so as to cover the fusible body, wherein a part of the intermediate film is directed from both sides of the fusible body toward the fusible body. The thermal fuse is extended to a space between the base film and the fusible body , and is opposed with a space therebetween .
A step of fixing a pair of terminal portions between a base film and an intermediate film, a step of bridging and joining a soluble body between the pair of terminal portions, and covering the soluble body on the base film And a step of ultrasonically welding the cover film as described above, wherein a part of the intermediate film is directed from both sides of the fusible body toward the fusible body and the base film. A method for producing a thermal fuse, characterized in that it is extended to a space between the solution and facing the space. 3. The method of manufacturing a thermal fuse according to claim 2, wherein the size of the space is larger than three times the thickness of the intermediate film and smaller than the width of the fusible body. The method for manufacturing a thermal fuse according to claim 2, wherein the space is formed so as to cross obliquely with respect to the extending direction.

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