A temperature fuse which can be reflow soldered and a reflow soldering method thereof

Abstract

The present application relates to the field of temperature fuse, in particular to a temperature fuse capable of reflow soldering and a reflow soldering method thereof. The present application discloses a temperature fuse capable of reflow soldering and a reflow soldering method thereof, wherein the temperature fuse capable of reflow soldering comprises an insulating shell, a fixed electrode, an elastic electrode and a thermal element, the fixed end of the fixed electrode and the elastic end of the elastic electrode are located in the insulating shell, the elastic end of the elastic electrode is fixedly connected with the fixed end of the fixed electrode through the thermal element after elastic deformation, the elastic electrode has soft magnetism, and is used for interacting with a magnetic field to generate magnetic attraction force so as to limit the elastic end of the elastic electrode from separating from the fixed end of the fixed electrode. The temperature fuse of the present application can be reflow soldered, has simple structure, is easy to realize, and is easy to realize large-scale production.

Description

Technical Field

[0001] This invention belongs to the field of thermal fuses, and specifically relates to a thermal fuse that can be reflow soldered and a reflow soldering method thereof. Background Technology

[0002] With social development and technological progress, electrical products have permeated all aspects of production and life. It can be said that people are dealing with electrical products every moment nowadays, and fire accidents caused by electrical products are also commonplace.

[0003] Due to the inherent resistance of electrical products, some electrical energy is converted into heat during use. Combined with abnormal heating caused by aging, short circuits, etc., if the current is not cut off in time, the temperature will exceed the maximum allowable temperature of the electrical product, leading to a fire. This is the basis for the demand for thermal fuses.

[0004] According to the national standard GB9816.1-2013, a thermal fuse, also called a thermal circuit breaker or thermal circuit breaker, is a non-resettable device with a thermal element that cuts off the current when exposed to a temperature exceeding its design for a certain period of time.

[0005] A thermal fuse works by using a thermal element to sense overheating caused by abnormal factors during operation. When the temperature exceeds the design temperature for a certain period, the thermal element changes its state from solid to liquid, thus cutting off the current and preventing a fire. This protection is one-time only and cannot be reused after activation.

[0006] Thermal fuses have become quite mature after years of development. They can be classified into alloy type and organic type according to the material of the thermal element.

[0007] The development of alloy thermal fuses has gone through a process from non-environmentally friendly (containing heavy metals such as Pb and Cr) to environmentally friendly. The temperature range they protect is mainly 76℃~150℃, and they also have some applications in the 150℃~230℃ range.

[0008] Because the rated temperature of the thermal element in a thermal fuse is much lower than the minimum temperature required for the reflow zone in reflow soldering (approximately 250°C), ordinary thermal fuses cannot be reflow soldered and can only be soldered locally using methods such as spot soldering or laser soldering. This limitation restricts their application in large-scale SMT production. Summary of the Invention

[0009] The purpose of this invention is to provide a temperature fuse that can be reflow soldered and a reflow soldering method thereof to solve the above-mentioned technical problems.

[0010] To achieve the above objectives, the technical solution adopted by the present invention is as follows: a temperature fuse that can be reflow soldered, comprising an insulating shell, a fixed electrode, an elastic electrode, and a heating element. The fixed end of the fixed electrode and the elastic end of the elastic electrode are located inside the insulating shell. After the elastic end of the elastic electrode undergoes elastic deformation, it is fixedly electrically connected to the fixed end of the fixed electrode through the heating element. The elastic electrode has soft magnetism and is used to interact with a magnetic field to generate magnetic attraction force to restrict the elastic end of the elastic electrode from detaching from the fixed end of the fixed electrode.

[0011] Furthermore, it also includes a permanent magnet, which is detachably mounted outside the insulating shell. The permanent magnet and the elastic electrode are magnetically attracted to each other, thus preventing the elastic end of the elastic electrode from detaching from the fixed end of the fixed electrode.

[0012] Furthermore, the permanent magnet is made of magnetic material.

[0013] Furthermore, the fixed electrode is made of a non-magnetic metal material.

[0014] Furthermore, the elastic electrode is made of a metal material with soft magnetic properties.

[0015] Furthermore, the elastic electrode is made of a non-magnetic metal material, and the elastic end of the elastic electrode is fitted with a metal sleeve with soft magnetism.

[0016] Furthermore, the heating element is a low-temperature alloy.

[0017] Furthermore, the bottom opening of the insulating shell also includes an I-shaped cover plate, the upper end of which extends into the insulating shell, the fixed end of the fixed electrode is supported on the upper end of the I-shaped cover plate, the lower end of the I-shaped cover plate covers the opening of the insulating shell, and the other ends of the fixed electrode and the elastic electrode extend out of the insulating shell and abut against the bottom surface of the lower end of the I-shaped cover plate.

[0018] Furthermore, the fixed end of the fixed electrode abuts against the inner top surface of the insulating shell, and the elastic end of the elastic electrode is located below the fixed end of the fixed electrode.

[0019] The present invention also provides a reflow soldering method for a thermal fuse, applicable to the above-mentioned reflow solderable thermal fuse, comprising the following steps:

[0020] S1 provides a magnetic field that acts on the elastic electrode to generate a magnetic attraction force, which restricts the elastic end of the elastic electrode from detaching from the fixed end of the fixed electrode.

[0021] S2, reflow soldering of the thermal fuse;

[0022] S3, after reflow soldering is completed, remove the magnetic field.

[0023] Beneficial technical effects of the present invention:

[0024] The thermal fuse of this invention can be reflow soldered, is easy to operate, can be applied to large-scale SMT production, and has a simple structure that is easy to implement. Attached Figure Description

[0025] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0026] Figure 1 This is a structural diagram of a temperature fuse according to an embodiment of the present invention;

[0027] Figure 2 This is a schematic diagram showing the open state of the temperature fuse in one embodiment of the present invention;

[0028] Figure 3 This is a structural diagram of the temperature fuse in Embodiment 2 of the present invention;

[0029] Figure 4 This is a schematic diagram showing the open state of the temperature fuse in Embodiment 2 of the present invention; Detailed Implementation

[0030] To further illustrate the various embodiments, the present invention provides accompanying drawings. These drawings are part of the disclosure of the present invention, primarily used to illustrate the embodiments and to explain the operating principles of the embodiments in conjunction with the relevant descriptions in the specification. With reference to these drawings, those skilled in the art should be able to understand other possible implementations and the advantages of the present invention. Components in the drawings are not drawn to scale, and similar component symbols are generally used to represent similar components.

[0031] The present invention will now be further described in conjunction with the accompanying drawings and specific embodiments.

[0032] Example 1

[0033] like Figure 1 and 2 As shown, a reflow solderable temperature fuse includes an insulating housing 5, a fixed electrode 1, an elastic electrode 2, and a heating element 3. The fixed end 11 of the fixed electrode 1 and the elastic end 21 of the elastic electrode 3 are located inside the insulating housing 5. After the elastic end 21 of the elastic electrode 2 undergoes elastic deformation, it is electrically connected to the fixed end 11 of the fixed electrode 1 by welding through the heating element 3. When the heating element 3 melts, the elastic end 21 of the elastic electrode 2 will spring open and detach from the fixed end 11 of the fixed electrode 1 under the action of elastic restoring force.

[0034] The elastic electrode 2 has soft magnetism and is used to interact with a magnetic field to generate magnetic attraction force to restrict the elastic end 21 of the elastic electrode 21 from detaching from the fixed end 11 of the fixed electrode 1. That is, the magnetic attraction force generated by the magnetic field on the elastic electrode 21 is not less than the elastic restoring force of the elastic end 21 of the elastic electrode 2, so that the elastic end 21 of the elastic electrode 2 will not elastically reset after the heating element 3 melts.

[0035] Preferably, the fixed electrode 1 is made of a non-magnetic metal material to avoid the residual magnetism of the fixed electrode 1 after the magnetic field is removed, which may attract the elastic electrode 2 and prevent it from detaching, thus affecting the normal temperature protection function, but this is not a limitation.

[0036] In this specific embodiment, the fixed electrode 1 is preferably made of copper, which has good conductivity, is easy to manufacture, and has a low cost. Of course, in some embodiments, the fixed electrode 1 may also be made of other non-magnetic metal materials.

[0037] Preferably, in this specific embodiment, the elastic electrode 2 is made of a metal material with soft magnetic properties, such as iron or iron alloys, which has good conductivity, good elasticity, is easy to manufacture, and has a low cost, but this is not a limitation.

[0038] Preferably, in this specific embodiment, both the fixed electrode 1 and the elastic electrode 2 are strip-shaped sheet structures, which have good performance. However, this is not a limitation, and in some embodiments, other structures can also be used.

[0039] In this specific embodiment, the heating element 3 is preferably a low-temperature alloy, such as a solder alloy, which is easy to implement, low in cost, and has a wide melting temperature range, but is not limited thereto.

[0040] The heating element 3 can be used to weld the fixed end 11 of the fixed electrode 1 and the elastic end 21 of the elastic electrode 3 together by means of hot welding, laser welding, etc. Flux can be used to assist the welding process.

[0041] In this specific embodiment, the bottom opening of the insulating shell 5 also includes an I-shaped cover plate 4. The upper end of the I-shaped cover plate 4 extends into the insulating shell 5, and the fixed end 11 of the fixed electrode 1 is supported on the upper end of the I-shaped cover plate 4. The lower end of the I-shaped cover plate 4 covers the opening of the insulating shell 5, and the other ends 12 and 22 of the fixed electrode 1 and the elastic electrode 2 extend out of the insulating shell 5 and abut against the bottom surface of the lower end of the I-shaped cover plate 4 for SMT soldering. The lower end of the I-shaped cover plate 4 can be fixed to the opening of the insulating shell 5 by snap-fit, sealant connection, or other fixing methods. The above structure is simple, compact, easy to manufacture, and low in cost, but it is not limited thereto.

[0042] In this specific embodiment, the fixed end 11 of the fixed electrode 1 abuts against the inner top surface of the insulating shell 5, and the elastic end 21 of the elastic electrode 2 is located below the fixed end 11 of the fixed electrode 1, making the fixed end 11 of the fixed electrode 1 more stable and the elastic end 21 of the elastic electrode 2 closer to the top wall of the insulating shell 5, so as to provide magnetic attraction for it, but it is not limited to this.

[0043] In this specific embodiment, a permanent magnet 6 is also included. The permanent magnet 6 is detachably disposed outside the insulating shell 5. The permanent magnet 6 and the elastic electrode 2 are magnetically attracted to each other, thus preventing the elastic end 21 of the elastic electrode 2 from detaching from the fixed end 11 of the fixed electrode 1. Using a permanent magnet 6 to provide a magnetic field is simple in structure, easy to implement, convenient to use, and low in cost. However, it is not limited to this. In some embodiments, coils, electromagnets, etc., can also be used to provide a magnetic field.

[0044] Preferably, in this specific embodiment, the permanent magnet 6 is adsorbed on the upper surface of the top of the insulating shell 5 and corresponds to the elastic end 21 of the elastic electrode 2. The magnetic field of the permanent magnet 6 acts on the elastic end 21 of the elastic electrode 2 and is magnetically attracted to the elastic end 21 of the elastic electrode 2. This not only reduces the magnitude of the magnetic field of the permanent magnet 6, thereby reducing the cost, but also makes it convenient to use. However, it is not limited to this. In some embodiments, the permanent magnet 6 can also be adsorbed at other suitable positions on the outer surface of the insulating shell 5.

[0045] Preferably, in this specific embodiment, the permanent magnet 6 is made of magnetic material, which has a strong magnetic field, is easy to implement, and has low cost, but it is not limited to this.

[0046] When the thermal fuse is reflow soldered, although the temperature in the reflow zone exceeds the rated temperature of the thermal fuse, causing the heating element 3 to change from solid to liquid, the permanent magnet 6 has a magnetic attraction to the elastic end 21 of the elastic electrode 2, preventing the elastic end 21 of the elastic electrode 2 from rebounding downwards and detaching from the fixed end 11 of the fixed electrode 1. After the reflow soldering is completed, once the temperature drops below the rated temperature of the thermal fuse, the heating element 3 changes from liquid to solid, fixing the elastic end 21 of the elastic electrode 2 and the fixed end 11 of the fixed electrode 1 in place. Then, the permanent magnet 6 is removed, and the low-temperature fusing performance of the thermal fuse is restored. When the temperature exceeds the rated temperature of the thermal fuse for a certain period of time, the heating element 3 changes from solid to liquid, and the elastic end 21 of the elastic electrode 2 rebounds downwards and disengages from the fixed end 11 of the fixed electrode 1. Figure 2 As shown, the circuit is cut off.

[0047] Example 2

[0048] like Figure 3 and 4As shown, the structure of this embodiment is largely the same as that of Embodiment 1, with the main difference being that the elastic electrode 2 is made of a non-magnetic metal material, and the elastic end 21 of the elastic electrode 2 is fitted with a softly magnetic metal sleeve 7. This structure facilitates the manufacture of the elastic electrode 2 and improves its performance.

[0049] In this specific embodiment, the elastic electrode 2 is preferably made of copper, which has good conductivity, is easy to manufacture, and has a low cost. Of course, in some embodiments, the elastic electrode 2 can also be made of other non-magnetic metal materials.

[0050] In this specific embodiment, the metal sleeve 7 is made of soft magnetic metal materials such as iron or iron alloys.

[0051] Of course, in some embodiments, the metal sleeve 7 can also be fitted onto other elastically deformable parts of the elastic electrode 2.

[0052] In some embodiments, a layer of soft magnetic metal may be provided only on the upper or lower surface of the elastic end 21 of the elastic electrode 2.

[0053] The reflow soldering process in this embodiment is similar to that in Embodiment 1. For details, please refer to Embodiment 1. It will not be described in detail here.

[0054] Example 3

[0055] The present invention also provides a reflow soldering method for a thermal fuse, applicable to the above-mentioned reflow solderable thermal fuse, comprising the following steps:

[0056] S1 provides a magnetic field that acts on the elastic electrode 2 to generate a magnetic attraction force, which restricts the elastic end 21 of the elastic electrode 2 from detaching from the fixed end 11 of the fixed electrode 1.

[0057] S2, reflow soldering the thermal fuse.

[0058] S3, after reflow soldering is completed, remove the magnetic field.

[0059] For a more detailed process, please refer to Implementation Example 1, which will not be elaborated here.

[0060] The thermal fuse of this invention can be reflow soldered, is easy to operate, can be applied to large-scale SMT production, and has a simple structure that is easy to implement.

[0061] Although the invention has been specifically shown and described in conjunction with preferred embodiments, those skilled in the art should understand that various changes in form and detail may be made to the invention without departing from the spirit and scope of the invention as defined in the appended claims, all of which shall be within the scope of protection of the invention.

Claims

1. A reflow-solderable temperature fuse, comprising an insulating housing, a fixed electrode, an elastic electrode, and a heating element, wherein the fixed end of the fixed electrode and the elastic end of the elastic electrode are located within the insulating housing, and the elastic end of the elastic electrode, after elastic deformation, is fixedly electrically connected to the fixed end of the fixed electrode through the heating element, characterized in that: The elastic end of the elastic electrode has soft magnetism, which is used to interact with a temporarily established external magnetic field during reflow soldering of the thermal fuse to generate magnetic attraction force and prevent the elastic end of the elastic electrode from detaching from the fixed end of the fixed electrode. Specifically, the external magnetic field is temporarily established when the thermal fuse is being reflow soldered; the external magnetic field is removed when the thermal fuse is not being reflow soldered. The fixed electrode is made of a non-magnetic metal material.

2. The reflow-solderable temperature fuse according to claim 1, characterized in that: The external magnetic field is established by a permanent magnet, which is detachably mounted outside the insulating shell. The permanent magnet and the elastic electrode are magnetically attracted to each other, thus preventing the elastic end of the elastic electrode from detaching from the fixed end of the fixed electrode.

3. The reflow-solderable temperature fuse according to claim 2, characterized in that: The permanent magnet is made of magnetic material.

4. The reflow-solderable temperature fuse according to claim 1, characterized in that: The fixed electrode is made of a non-magnetic metal material.

5. The reflow-solderable temperature fuse according to claim 1, characterized in that: The elastic electrode is made of a metal material with soft magnetic properties.

6. The reflow-solderable temperature fuse according to claim 1, characterized in that: The elastic electrode is made of a non-magnetic metal material, and the elastic end of the elastic electrode is fitted with a metal sleeve with soft magnetism.

7. The reflow-solderable temperature fuse according to claim 1, characterized in that: The heating element is a low-temperature alloy.

8. The reflow-solderable temperature fuse according to claim 1, characterized in that: The bottom opening of the insulating shell also includes an I-shaped cover plate. The upper end of the I-shaped cover plate extends into the insulating shell, the fixed end of the fixed electrode is supported on the upper end of the I-shaped cover plate, the lower end of the I-shaped cover plate covers the opening of the insulating shell, and the other ends of the fixed electrode and the elastic electrode extend out of the insulating shell and abut against the bottom surface of the lower end of the I-shaped cover plate.

9. The reflow-solderable temperature fuse according to claim 8, characterized in that: The fixed end of the fixed electrode abuts against the inner top surface of the insulating shell, and the elastic end of the elastic electrode is located below the fixed end of the fixed electrode.

10. A reflow soldering method for a thermal fuse, applicable to the reflow solderable thermal fuse as described in claim 1, characterized in that, Includes the following steps: S1 provides an external magnetic field that acts on the elastic electrode to generate a magnetic attraction force, which restricts the elastic end of the elastic electrode from detaching from the fixed end of the fixed electrode. S2, reflow soldering of the thermal fuse; S3, after reflow soldering is completed, remove the external magnetic field.

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