JP2013182750A - Temperature fuse and manufacturing method thereof - Google Patents

Abstract

An object of the present invention is to improve the reliability of a thermal fuse when a lead conductor is bent while accommodating a large current.
A thermal fuse according to the present invention includes a thermoplastic first insulating film 13 and a pair of strip-like members arranged on the upper surface of the first insulating film 13 so that their tip portions are opposed to each other with a space therebetween. The lead conductor 11, the fusible body 15 that connects the pair of lead conductors 11, and the first insulating film 13 having an opening that exposes the distal end portion 11 a and the fusible body 15 of the pair of lead conductors 11 A pair of intermediate films 14 and a second insulating film 17 joined to the first insulating film 13 via the intermediate film 14 so as to cover the distal end portion 11a of the lead conductor 11 and the fusible body 15. The entire surface of the lead conductor 11 that is in contact with the first insulating film 13 is embedded in the first insulating film 13 by heat sealing.
[Selection] Figure 7

Description

  The present invention relates to a thermal fuse used for preventing overheating of electronic devices and the like and a method for manufacturing the same.

  In the trend of electronic device miniaturization, it is desired to make a thermal fuse thinner. As a thin thermal fuse and a method for manufacturing the same, a technique as shown in Patent Document 1 is known. A method for manufacturing a thermal fuse according to this technique will be briefly described below.

  First, a pair of metal terminals is disposed on the upper surface of the first insulating material. Next, an insulating plate having an opening that exposes the ends of the pair of metal terminals is disposed on the upper surface of the first insulating material, and is heat-sealed while being pressurized. Then, after connecting the fuse element between the pair of metal terminals and applying the flux to the fuse element, the second insulating material is thermally fused to the insulating plate so as to cover the pair of metal terminals, the fuse element and the flux. A thermal fuse can be obtained by the above process.

JP 2000-164093 A (paragraphs (0025) to (0029), FIG. 6)

  A portable electronic device can be cited as an application of the thin thermal fuse. Portable electronic devices have increased the flow of large currents due to the high performance of devices and the increased capacity of lithium ion batteries.

  A thermal fuse through which a large current flows needs to have a low resistance value in order to suppress self-heating. As a method of reducing the resistance value, there is a method of increasing the thickness of the lead conductor. However, in the case of the above-described prior art thermal fuse, the metal terminal is merely fixed to the first insulating material by thermal fusion at the location where the insulating plate is located. For this reason, when the lead conductor becomes thick, when the lead conductor is bent, stress may be applied to the fusible body to deform the fusible body, or the connectivity between the fusible body and the lead terminal may be impaired.

  The method for manufacturing a thermal fuse of the present invention solves the above-mentioned problems of the prior art and aims to improve the reliability of the thermal fuse when the lead conductor is bent while accommodating a large current.

  According to a first aspect of the present invention, there is provided a step of embedding a pair of strip-like lead conductors in a thermoplastic first insulating film by heating and pressurizing them so as to face each other with a gap at the tip, and the lead conductors A step of fusing an intermediate film to the first insulating film and the pair of lead conductors so as to expose a front end portion thereof from the opening, a step of connecting a fusible body between the pair of lead conductors, A thermal fuse having a step of bonding and sealing the second insulating film to the first insulating film so that the fusible body is located in a space formed by the first insulating film and the second insulating film. It is a manufacturing method.

  According to the first aspect of the present invention, the lead conductor is embedded in the first insulating film by heat fusion by heating and pressurizing, and is integrated with the first insulating film and excellent in strength. Therefore, the lead conductor is bent. The stress applied to the fusible body due to the stress can be reduced. Thereby, even if the thickness of the lead conductor is increased, it is possible to prevent deformation of the fusible body due to bending stress and disconnection between the fusible body and the lead conductor. In addition, since the lead conductor is embedded by thermal fusion, the first insulating film is deformed along the fine irregularities on the side surface of the lead conductor. Since the film and the film are more firmly integrated, the stress applied to the fusible body can be further reduced.

  According to a second aspect of the present invention, there is provided a step of embedding a pair of strip-shaped lead conductors in the thermoplastic first insulating film by heating and pressurizing so as to face each other with a gap at a tip portion, Connecting the fusible body between the lead conductors, and connecting the second insulating film to the first insulating film so that the fusible body is located in a space formed by the first insulating film and the second insulating film. A method of manufacturing a thermal fuse having a step of sealing by bonding to a substrate.

  The invention according to claim 2 has the same effect as that of the invention according to claim 1.

  According to a third aspect of the present invention, there is provided a thermoplastic first insulating film, and a pair of strip-shaped lead conductors disposed on the upper surface of the first insulating film so that the tip portions thereof are opposed to each other with a space therebetween. A fusible body connecting between the pair of lead conductors, an intermediate film having an opening for exposing the distal end portion of the pair of lead conductors and the fusible body, and the first insulating film, A second insulating film joined to the first insulating film via the intermediate film so as to cover the front ends of the pair of lead conductors and the fusible body, and the second conductor in the pair of lead conductors 1 is a thermal fuse in which the entire surface in contact with one insulating film is embedded in the first insulating film by thermal fusion.

  According to the third aspect of the present invention, the entire surface of the portion where the lead conductor is in contact with the first insulating film is embedded in the first insulating film by heat fusion, and is integrated with the first insulator to increase the strength. Since it is excellent, the stress applied to the fusible body due to the stress that bends the lead conductor can be reduced. Thereby, even if the thickness of the lead conductor is increased, it is possible to prevent deformation of the fusible body due to bending stress and disconnection between the fusible body and the lead conductor. In addition, since the first insulating film deforms along the fine irregularities on the side surface of the lead conductor and integrates both, the anchor effect is exhibited, and the lead conductor and the first insulating film are more Since it is firmly integrated, the stress applied to the fusible body can be further reduced.

  According to a fourth aspect of the present invention, there is provided a thermoplastic first insulating film, and a pair of strip-shaped lead conductors disposed on the upper surface of the first insulating film so that the front ends thereof are opposed to each other with a space therebetween. A fusible body connecting the pair of lead conductors, and a second insulating film joined to the first insulating film so as to cover the distal ends of the pair of lead conductors and the fusible body, The entire surface of the portion of the pair of lead conductors in contact with the first insulating film is a thermal fuse embedded in the first insulating film by heat fusion.

  The invention according to claim 4 has the same effect as that of the invention according to claim 3.

  Even when the lead conductor is thick, the present invention can reduce the stress on the fusible body caused by bending the lead conductor, so that the reliability when bending the lead conductor while supporting a large current can be improved. It has an excellent effect that it can be achieved.

(A) Top view which shows the manufacturing method of the thermal fuse in Embodiment 1 of this invention, (b) Same side sectional drawing (A) Top view which shows the manufacturing method of the thermal fuse in Embodiment 1 of this invention, (b) Same side sectional drawing (A) Top view which shows the manufacturing method of the thermal fuse in Embodiment 1 of this invention, (b) Same side sectional drawing (A) Top view which shows the manufacturing method of the thermal fuse in Embodiment 1 of this invention, (b) Same side sectional drawing (A) Top view which shows the manufacturing method of the thermal fuse in Embodiment 1 of this invention, (b) Same side sectional drawing (A) Top view which shows the manufacturing method of the thermal fuse in Embodiment 1 of this invention, (b) Same side sectional drawing (A) The top view of the thermal fuse in Embodiment 1 of this invention, (b) Front sectional drawing of the thermal fuse (A) Top view which shows the manufacturing method of the thermal fuse in Embodiment 2 of this invention, (b) Same side sectional drawing (A) The top view of the thermal fuse in Embodiment 2 of this invention, (b) The front sectional drawing

(Embodiment 1)
The thermal fuse and the manufacturing method thereof according to Embodiment 1 of the present invention will be described with reference to the drawings.

  FIG. 1A is a plan view showing a method for manufacturing a thermal fuse in Embodiment 1 of the present invention, and FIG. 1B is a side sectional view of the thermal fuse. Similarly, FIGS. 2 (a), 3 (a), 4 (a), 5 (a), and 6 (a) are plan views showing the method for manufacturing the thermal fuse in the first embodiment of the present invention. 2 (b), FIG. 3 (b), FIG. 4 (b), FIG. 5 (b) and FIG. 6 (b) are side sectional views. 7A is a plan view of the thermal fuse in Embodiment 1 of the present invention, and FIG. 7B is a front sectional view of the thermal fuse.

  A lead conductor 11 shown in FIGS. 1A and 1B is a rectangular Ni plate, and a metal layer 12 is formed along the longitudinal direction at a substantially central portion in the short side direction. The metal layer 12 is formed by plating, and a material having good solder wettability such as Au or Sn is used. In addition, since the metal layer 12 is very thin, illustration is abbreviate | omitted in side surface sectional drawing.

  As shown in FIGS. 2A and 2B, the lead conductor 11 is processed into a paired shape by pressing so that the tip end portions 11a face each other with a space therebetween.

  As shown in FIGS. 3A and 3B, the lead conductor 11 is heated while applying pressure to the first insulating film 13 to embed the lead conductor 11 in the first insulating film 13 by heat fusion. At this time, the upper surface of the lead conductor 11 is embedded until it is flush with the upper surface of the first insulating film 13. Further, since not only a part of the lead conductor 11 in contact with the first insulating film 13 is embedded, but the entire surface is embedded, the leading end portion 11a of the lead conductor 11 is also integrated with the first insulating film 13. Therefore, deformation of the lead conductor 11 with respect to bending stress can be further reduced. The first insulating film 13 uses a thermoplastic resin, and for example, PET, PEN, and the like are suitable.

  As shown in FIGS. 4A and 4B, the intermediate film 14 is heat-sealed to the first insulating film 13 so as to sandwich the lead conductor 11. The intermediate film 14 is made of the same material as the first insulating film 13. The intermediate film 14 has an opening, and the leading end portion 11a of the lead conductor 11 and the metal layer 12 are exposed from the opening.

  As shown in FIGS. 5A and 5B, the fusible body 15 is connected between the pair of lead conductors 11. This connection method is by welding. The fusible body 15 is welded to the portion of the lead conductor 11 where the metal layer 12 is formed. The fusible body 15 is made of an alloy having a low melting point corresponding to the operating temperature of the thermal fuse, for example, an alloy of Sn and In.

  As shown in FIGS. 6A and 6B, the second insulating film 17 is thermally fused to the intermediate film 14, and the fusible body 15 is sealed with the second insulating film 17 and the first insulating film 13. . A flux 16 is present on the surface of the soluble body 15. The flux 16 may be applied to the fusible body 15 before the second insulating film 17 is fused to the intermediate film 14, or the flux 16 is applied to the second insulating film 17 and the second insulating film is applied. When fusing 17 to the intermediate film 14, or after fusing, the flux 16 may be applied to the soluble material at a temperature at which it has fluidity.

  By cutting the lead conductor 11, the first insulating film 13, the intermediate film 14, and the second insulating film 17 at predetermined positions from the state of FIG. 6A, the temperatures shown in FIGS. 7A and 7B are obtained. A fuse 20 is obtained.

  In the thermal fuse 20 of the present embodiment, since the lead conductor 11 is embedded in the first insulating film 13, even if the thickness of the lead conductor 11 is increased to cope with a large current, the lead conductor 11 is first insulated. Since the film 13 is fixed not only at the fused portion with the second insulating film 17 but also as a whole, the stress applied to the fusible body 15 when the lead conductor 11 is bent can be reduced, and the reliability of the thermal fuse Can be improved. In particular, in the present embodiment, since the lead conductor 11 is embedded in the first insulating film 13 by thermal fusion, the first insulating film 13 is deformed along the fine irregularities on the side surface of the lead conductor 11. Therefore, the lead conductor 11 bites into the first insulating film 13, and the lead conductor 11 and the first insulating film 13 are firmly integrated by a so-called anchor effect. Thereby, the stress applied to the fusible body 15 when the lead conductor 11 is bent can be further reduced.

  In the present embodiment, the following variations can be employed.

  As a first variation, the method of manufacturing the plurality of thermal fuses 20 from the plate-like lead conductor 11 has been described. However, the plurality of thermal fuses 20 may be manufactured from the lead conductor 11 of the hoop material, You may manufacture one by one.

  As another variation, the upper surface of the lead conductor 11 is embedded until it is the same height as the upper surface of the first insulating film 13, but the lead conductor 11 can also be kept at a higher position. Such variations are useful when the thickness of the first insulating film 13 is very thin. Specifically, half of the lead conductor 11 in the thickness direction can be embedded in the first insulating film 13. Of course, 1/2 or more may be embedded.

  Further, by providing a rough surface on the back surface of the lead conductor 11 to provide unevenness on the back surface, a further anchor effect is obtained, and the lead conductor 11 and the first insulating film 13 are more firmly integrated. You can also

  The above variations can be implemented alone or in any combination.

(Embodiment 2)
The thermal fuse and the manufacturing method thereof according to Embodiment 2 of the present invention will be described below. 8A is a plan view showing a method for manufacturing a thermal fuse in Embodiment 2 of the present invention, FIG. 8B is a side sectional view of the thermal fuse, and FIG. 9A is an embodiment of the present invention. FIG. 9B is a plan view of the thermal fuse in FIG. 2, and FIG. 9B is a front sectional view of the thermal fuse.

  The thermal fuse and the manufacturing method thereof according to the second embodiment are obtained by eliminating the intermediate film 14 in the first embodiment and directly heat-sealing the second insulating film 17 to the first insulating film 13. Other than this, the technique is the same as that of the first embodiment.

  As a specific manufacturing method, FIGS. 1 to 3 in the first embodiment are the same. From the state of FIG. 3, the fusible body 15 is connected by welding between the pair of lead conductors 11 without heat-sealing the intermediate film 14 as shown in FIGS. 8 (a) and 8 (b). Thereafter, the second insulating film 17 is fused to the first insulating film 13, and the fusible body 15 is sealed with the second insulating film 17 and the first insulating film 13. Thereafter, the thermal fuse 20 shown in FIGS. 9A and 9B can be obtained by cutting at a predetermined position.

  This embodiment also has the same function and effect as the first embodiment. Moreover, the variation in Embodiment 1 is applicable also in this Embodiment.

  The method for manufacturing a thermal fuse according to the present invention is applicable when manufacturing a thermal fuse for preventing overheating of an electronic device.

DESCRIPTION OF SYMBOLS 11 Lead conductor 11a Tip part 12 Metal layer 13 1st insulating film 14 Intermediate film 15 Soluble body 16 Flux 17 2nd insulating film 20 Thermal fuse

Claims (4)

A step of embedding a pair of strip-shaped lead conductors in the thermoplastic first insulating film by heating and pressurizing them so as to oppose each other with a gap at the tip part; and
Fusing the intermediate film to the first insulating film and the pair of lead conductors so that the leading end of the lead conductor is exposed from the opening;
Connecting a fusible body between the pair of lead conductors;
A temperature having a step of bonding and sealing the second insulating film to the first insulating film so that the fusible body is located in a space formed by the first insulating film and the second insulating film. Fuse manufacturing method. A step of embedding a pair of strip-shaped lead conductors in the thermoplastic first insulating film by heating and pressurizing them so as to oppose each other with a gap at the tip part; and
Connecting a fusible body between the pair of lead conductors;
A temperature having a step of bonding and sealing the second insulating film to the first insulating film so that the fusible body is located in a space formed by the first insulating film and the second insulating film. Fuse manufacturing method. A thermoplastic first insulating film;
A pair of strip-shaped lead conductors disposed on the upper surface of the first insulating film so as to face each other with a tip portion spaced apart from each other;
A fusible member connecting between the pair of lead conductors;
An intermediate film that has an opening for exposing the end portions of the pair of lead conductors and the fusible body, and is bonded to the first insulating film;
A second insulating film joined to the first insulating film via the intermediate film so as to cover the distal ends of the pair of lead conductors and the fusible body,
A thermal fuse in which the entire surface of the pair of lead conductors in contact with the first insulating film is embedded in the first insulating film by thermal fusion. A thermoplastic first insulating film;
A pair of strip-shaped lead conductors disposed on the upper surface of the first insulating film so as to face each other with a tip portion spaced apart from each other;
A fusible member connecting between the pair of lead conductors;
A second insulating film joined to the first insulating film so as to cover the distal ends of the pair of lead conductors and the fusible body,
A thermal fuse in which the entire surface of the pair of lead conductors in contact with the first insulating film is embedded in the first insulating film by thermal fusion.

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