TW201802854A - Current fuse - Google Patents

Abstract

Provided is a lead-free current fuse such that connectivity to terminal portions are improved, an increase in current rating can be handled without leading to an increase in resistance value, and an abnormal overheating of the terminal portions can be suppressed during fusing time. The current fuse has two engaging terminal portions 2, 2, and a fusing portion 3 provided between the engaging terminal portions 2, 2. The fusing portion 3 is formed from a fusible conductor 6 having a lead-free, low-melting-point metal 4, and a lead-free, first high-melting-point metal 5 being layered therein, the first high-melting-point metal 5 having a higher melting point than the low-melting-point metal 4.

Description

Current fuse

The present invention relates to a current fuse which is installed on a current path and cuts off and blocks the current path due to self-heating when a current exceeding a rated value flows. This application is based on and claims priority from Japanese Patent Application No. 2016-030512 filed in Japan on February 19, 2016, and the application is used in the present application by reference.

In the past, as electronics. The safety device for electrical circuits such as electrical equipment uses so-called buckle fuses as shown in Figs. 16 (A) and 16 (B). Connection media 93 such as solder are used by wire or ribbon fuses 92. A current fuse 90 is connected between a pair of button terminals 91 and 91. 16 (A) is a plan view showing an example of a conventional current fuse, and FIG. 16 (B) is a sectional view taken along the line A-A 'of FIG. 16 (A).

Regarding this type of current fuse 90, a copper terminal is generally used as the buckle terminal 91, and a fuse made of a wire or ribbon-like fusible alloy with a small amount of Sn, Ag and the like is generally used as the fuse portion 92. As for the component, when the electric circuit passes an overcurrent exceeding a predetermined capacity, the fuse section 92 will instantly fuse to ensure the safety of the machine.

Prior art literature

Patent literature

Patent Document 1: Japanese Patent Application Laid-Open No. 2002-352686

Conventional buckle fuses are those in which lead terminals 91 are connected to both ends of a fuse portion 92 using a lead alloy or the like as a fuse member, or the fuse portion 92 and the button terminals 91 are integrally formed by a zinc alloy. However, lead alloys, which are harmful metals with a large environmental load, require strong reductions similar to those of cadmium, mercury, or their alloys.

The Sn alloy, which is a lead replacement material, is difficult to be used as a fusible member because the Sn alloy is melted during soldering in connection with the buckle terminal 91. Moreover, the melting point of zinc alloy is about 400 ℃, which is nearly 100 ℃ higher than that of lead alloy, and the specific resistance is about 6μΩ. cm, compared to about 21μΩ of lead alloy. cm is lower than 1/3. Therefore, the temperature of the buckle terminal 91 at the time of fusing becomes high temperature, and there is a risk of causing thermal influence on peripheral components such as the terminal portion of the circuit board to which the buckle fuse is connected, the machine body or the user. For this reason, it is necessary to perform processing such as thinning the fuse portion 92 locally, but the resistance value tends to increase and it is difficult to cope with a higher current rating.

Therefore, an object of the present invention is to provide a current fuse which can improve the connection to the terminal portion, can increase the current rating without increasing the resistance value, and can suppress abnormal overheating of the terminal portion at the time of fusing.

Furthermore, it is another object of the present invention to provide a lead-free current fuse that can also be enhanced to cope with environmental restrictions.

In order to solve the above problems, the current fuse of the present invention has two engagement terminal portions and a fuse portion provided between the engagement terminal portions. The fuse portion is formed by laminating a low melting point metal and a melting point higher than the above. The first high-melting metal soluble conductor of the low-melting metal is formed.

Further, in the current fuse of the present invention, the low-melting-point metal-based sn or an alloy whose main component is Sn, and the first high-melting-point metal-based Ag or Cu or an alloy whose main component is Ag or Cu.

According to the present invention, the soluble conductive system is laminated with a laminate of a low-melting-point metal and a first high-melting-point metal. Therefore, when the low-melting-point metal has melted, such as when soldering the engaging terminal portion, the first high It is covered with a melting point metal, so it does not melt and solder connection is possible.

In addition, the soluble conductor is laminated with a low-melting-point metal having a melting point lower than that of the first high-melting-point metal. Therefore, the self-heating caused by the overcurrent starts to melt from the melting point of the low-melting-point metal and begins to erode the first high-melting-point metal. 1 High-melting metals melt at temperatures below their own melting points. Therefore, according to the present invention, it is possible to prevent overheating of the engaging terminal portion, and use the melting effect of the low-melting-point metal on the first high-melting-point metal to quickly melt the soluble conductor to block the current path.

1‧‧‧current fuse

2‧‧‧ Engagement terminal

3‧‧‧Fuse

4‧‧‧ low melting point metal

5‧‧‧ the first high melting point metal

6‧‧‧ soluble conductor

7‧‧‧Connecting material

9‧‧‧Deformation limitation section

10‧‧‧hole

10a‧‧‧ side

10b‧‧‧ Underside

11‧‧‧ 2nd high melting point metal

13‧‧‧ the first high melting point particle

15‧‧‧ 2nd high melting point particle

16‧‧‧ flange

17‧‧‧ groove

20‧‧‧Current Fuse

Fig. 1 (A) is a top view of a current fuse to which the present invention is applied, and Fig. 1 (B) is a cross-sectional view taken along A-A 'of Fig. 1 (A).

Fig. 2 (A) is a top view of a current fuse provided with a deformation limiting portion in a fuse portion, and Fig. 2 (B) is a cross-sectional view taken along A-A 'of Fig. 2 (A).

FIG. 3 (A) is a cross-sectional view of a soluble conductor with non-through holes formed before heating, and FIG. 3 (B) is a cross-sectional view of a soluble conductor shown in FIG. 3 (A) after heating.

Fig. 4 (A) is a cross-sectional view showing a soluble conductor filled with a second high-melting-point metal in a through-hole, and Fig. 4 (B) is a cross-sectional view showing a soluble conductor filled with a second high-melting-point metal in a non-through-hole. .

FIG. 5 (A) is a cross-sectional view of a soluble conductor provided with a through-hole having a rectangular cross-section, and FIG. 5 (B) is a cross-sectional view of a soluble conductor provided with a non-through-hole having a rectangular cross-section.

6 is a cross-sectional view showing a soluble conductor provided with a second refractory metal up to the opening end side of the hole.

FIG. 7 (A) is a cross-sectional view showing a soluble conductor having non-through holes formed in opposite directions, and FIG. 7 (B) is a cross-sectional view showing a soluble conductor having non-through holes formed in opposite directions.

FIG. 8 is a cross-sectional view showing a soluble conductor in which a first high-melting-point particle is incorporated in a low-melting-point metal.

FIG. 9 (A) is a cross-sectional view of a soluble conductor mixed with first high-melting-point particles having a particle size smaller than the thickness of the low-melting metal in a low-melting metal before heating, and FIG. 9 (B) is a view showing FIG. 9 (A) The cross section of the soluble conductor shown after heating.

FIG. 10 is a cross-sectional view showing a soluble conductor in which second high-melting-point particles are pressed into a low-melting-point metal.

11 is a cross-sectional view showing a soluble conductor in which the second high-melting-point particles are pressed into the first high-melting-point metal and the low-melting-point metal.

12 is a cross-sectional view showing a soluble conductor having flange portions formed on both ends of the second high-melting-point particles.

Fig. 13 (A) is a plan view of a current fuse provided with a deformation limiting portion having a groove formed in the fuse portion before heating, and Fig. 13 (B) is a cross-sectional view taken along the line A-A 'of Fig. 13 (A).

Fig. 14 (A) is a plan view showing a current fuse in which an engaging terminal portion and a fuse portion are formed by a soluble conductor, and Fig. 14 (B) is a cross-sectional view taken along A-A 'of Fig. 14 (A).

FIG. 15 (A) is a plan view showing a current fuse in which an engaging terminal portion and a fuse portion are formed by a soluble conductor provided with a deformation restricting portion, and FIG. 15 (B) is an AA ′ section of FIG. 15 (A) Illustration.

FIG. 16 (A) is a plan view showing an example of a conventional current fuse, and FIG. 16 (B) is a view of FIG. 16 (A) A-A 'sectional view.

Hereinafter, a current fuse to which the present invention is applied will be described in detail with reference to the drawings. The present invention is not limited to the following embodiments, and various changes can be made without departing from the scope of the present invention. In addition, the drawings are schematic, and the ratios and the like of the dimensions may be different from the actual ones. Specific dimensions and the like should be determined with reference to the following description. Moreover, it is a matter of course that the respective drawings also include portions having different dimensional relationships or ratios.

[Current fuse]

As shown in FIG. 1, the current fuse 1 to which the present invention is applied has two engaging terminal portions 2 and a fuse portion 3 provided between the engaging terminal portions 2. In the current fuse 1, the two engaging terminal portions 2 are engaged between the terminal portions of the electrical circuit and are screwed or the like, thereby being assembled to the current path of the electrical circuit. In addition, the current fuse 1 causes the fuse circuit 3 to be instantaneously blown when the electrical circuit flows an overcurrent exceeding a predetermined capacity, thereby blocking the current path between the pair of engaging terminal portions 2 to ensure the safety of the machine.

[Engagement terminal part]

The engaging terminal portion 2 has a known open shape such as a partially open buckle shape or a substantially disc shape with a central opening, and can be engaged with a terminal portion of an electrical circuit (not shown). Removably engaged. The material of the engagement terminal portion 2 is not particularly limited as long as it has moderate rigidity and good electrical conductivity, and copper, copper-nickel alloy, and the like are suitably used.

In the current fuse 1, a fuse portion 3 is connected between a pair of engaging terminal portions 2 by a connecting material 7 such as solder, and is conducted through the fuse portion 3. In addition, the connecting material 7 is not limited to solder, and any material that can conduct the connection between the engaging terminal portion 2 and the fuse portion 3 may be used.

[Fuse section]

The fuse section 3 is fused when an overcurrent exceeding a predetermined capacity is passed, thereby blocking the current path across the pair of engaging terminal sections 2. The fusing portion 3 is formed by laminating a soluble conductor 6 having a low melting point metal 4 and a first high melting point metal 5 having a higher melting point than the low melting point metal 4.

The first high melting point metal 5 is preferably Ag, Cu, or an alloy containing Ag or Cu as a main component, and has heating when connected to the engaging terminal portion 2 or when soldering a current fuse 1 to a terminal portion of a circuit board. High melting point that does not melt at temperature. The first high-melting-point metal 5 preferably has a content rate of 1,000 ppm or less of the RoHS directive when it contains lead.

The low-melting-point metal 4 is not particularly limited as long as it has a melting point as a melting point when the temperature rises to a predetermined temperature due to an overcurrent. For example, Sn or an alloy containing Sn as a main component is suitably used. "Pb-free solder" material. The melting point of the low melting point metal 4 is not necessarily higher than the temperature of the solder connection, and it can be melted at about 200 ° C. In addition, the low-melting-point metal 4 can also be made of Bi, In or an alloy containing Bi or In, which will melt at a lower temperature of about 120 ° C to 140 ° C. The low melting point metal 4 can be freely set to a desired melting point temperature by selecting these metals or alloying them in a predetermined ratio. In addition, when the low-melting-point metal 4 contains lead, the content rate is preferably set to 1000 ppm or less of the RoHS directive.

The soluble conductor 6 is a layered body having a first high melting point metal 5 at least on the front and back surfaces of the low melting point metal 4, preferably, a low melting point metal 4 forming an inner layer and a first high melting point metal 5 forming an outer layer. structure. Therefore, when the low-melting-point metal 4 is melted, such as when the solder is connected to the engaging terminal portion 2, the soluble conductor 6 is covered with the first high-melting-point metal 5, so that it does not melt, and solder connection can be performed. Manufactured in the same manner as before.

Furthermore, the soluble conductor 6 is laminated with a low-melting-point metal 4 having a melting point lower than that of the first high-melting-point metal 5. Therefore, self-heating due to an overcurrent starts from the melting point of the low-melting-point metal 4. Melt and begin to attack the first high melting point metal 5. For example, when the low-melting-point metal 4 is composed of an Sn-Bi-based alloy or an In-Sn-based alloy, the soluble conductor 6 starts to melt from a low temperature of about 140 ° C or 120 ° C. In addition, the current fuse 1 uses the erosion effect (solder erosion) of the low melting point metal 4 on the first high melting point metal 5 to melt the first high melting point metal 5 at a temperature lower than its own melting point. Therefore, the soluble conductor 6 can prevent overheating of the engaging terminal portion 2, and can quickly fuse by using the melting effect of the low-melting-point metal 4 on the first high-melting-point metal 5 to block the current path.

In addition, the soluble conductor 6 is covered with a high-melting-point metal, so that the melting temperature can be greatly reduced compared to the conventional current fuse composed of a high-melting-point metal such as Cu. Therefore, there is no need to locally thin the fuse portion. Can increase the rated value to cope with large current. In addition, compared with the conventional soluble conductors using lead-based high melting point solder, the conductor resistance can be greatly reduced, and the current rating can be greatly increased compared with the conventional current fuses and the like of the same size. In addition, compared with conventional current fuses having the same current rating, it is possible to reduce the size and thickness.

In addition, the soluble conductor 6 can improve the resistance (pulse resistance) to a sudden surge of an abnormally high voltage applied to the electrical system in which the current fuse 1 is incorporated. That is, the soluble conductor 6 does not melt even when a current of 100 A flows for several milliseconds, for example. In this regard, since a large current flowing in a very short time will flow through the surface layer (skin effect) of the conductor, the soluble conductor 6 is provided with a first high-melting-point metal 5 having a low resistance value such as Ag plating as the outer layer Therefore, it is easy to flow a current applied by a surge, which can prevent melting due to self-heating. Therefore, the soluble conductor 6 is more resistant to surges than a conventional fuse made of a solder alloy.

Furthermore, in consideration of environmental pollution, it is desirable to control the use of harmful metals such as lead or cadmium, mercury, or alloys thereof as much as possible as the material used in the soluble conductor 6. In current buckle fuses, the soluble guidance system is based on materials (lead, tin, zinc, or other materials Etc. as the main component of the alloy). As mentioned above, the low melting temperature of tin-based materials has a defect in solder connectivity with copper terminals, while zinc-based materials have a relatively high melting point, so there is a problem of thermal effects during melting. In addition, although lead-based materials can easily solve these problems and are not currently subject to environmental restrictions (correction of the RoHS directive), they may be targeted for reduction in the future in accordance with social needs.

In this regard, according to the current fuse 1 to which the present invention is applied, by forming a soluble conductor 6 without using a lead-based harmful metal, it is also possible to cope with the strengthening of environmental restrictions. Furthermore, as described above, the soluble conductor 6 is a laminated structure in which the low-melting-point metal 4 constitutes the inner layer and the first high-melting-point metal 5 constitutes the outer layer, thereby maintaining the solder connection to the engagement terminal portion 2 of the copper. Shape, and when melted, it will melt at a lower temperature, which can prevent the engaging terminal portion 2 from overheating, and can be quickly melted to block the current path.

The soluble conductor 6 can be produced by forming the first high-melting-point metal 5 on the surface of the low-melting-point metal 4 by using a film-forming technique such as electrolytic plating. For example, the soluble conductor 6 can be efficiently manufactured by applying Ag plating to the surface of a solder foil that has been formed into a predetermined shape. The connection terminal 7 is connected to the engagement terminal portion 2 by a connection material 7 such as solder.

In addition, the soluble conductor 6 can be connected to the engaging terminal portion 2 by welding. Thereby, the pair of engaging terminal portions 2 can also be electrically connected via the soluble conductor 6.

In addition, the soluble conductor 6 is preferably formed such that the volume of the low-melting metal 4 is larger than the volume of the first high-melting metal 5. The soluble conductor 6 can melt the low-melting-point metal 4 by self-heating to cause the first high-melting-point metal 5 to be eroded, thereby rapidly melting and melting. Therefore, the soluble conductor 6 can accelerate the ablation effect by forming the volume of the low-melting-point metal 4 to be larger than the volume of the first high-melting-point metal 5, thereby quickly blocking the space between the pair of engaging terminal portions 2.

[Deformation restriction part]

Further, the soluble conductor 6 may form a deformation restricting portion 9 that suppresses the flow of the low-melting-point metal 4 that melts during solder connection and the like, and restricts deformation.

As shown in FIG. 2, in the deformation restricting portion 9, at least a part of the side surface 10 a of the low melting point metal 4 or the plurality of holes 10 is covered with a second high melting point metal 11 continuous with the first high melting point metal 5. The hole 10 can be formed by, for example, piercing a sharp body such as a needle into the low-melting-point metal 4, or performing a pressing process on the low-melting-point metal 4 using a mold. Further, the holes 10 are uniformly formed over the entire surface of the low-melting metal 4 in a predetermined pattern, for example, a square lattice shape or a hexagonal lattice shape.

The constituent material of the second high melting point metal 11 is the same as the constituent material of the first high melting point metal 5 and has a high melting point that does not melt at the solder connection temperature. In addition, the second high-melting-point metal 11 is formed from the same material as the first high-melting-point metal 5 in the step of forming the first high-melting-point metal 5 together, which is preferable in terms of manufacturing efficiency.

As shown in FIG. 2, the soluble conductor 6 is connected between a pair of engagement terminal portions 2 through a connection material 7 such as solder or by welding. At this time, in the soluble conductor 6, the first high-melting-point metal 5 that is not melted at the connection temperature is laminated on the low-melting-point metal 4 as the outer layer and the deformation restricting portion 9 is provided, thereby being exposed to a high-temperature environment. Then, the deformation of the soluble conductor 6 can be controlled within a certain range that can suppress the unevenness of the fusing characteristics. Therefore, the soluble conductor 6 can suppress the variation of the fusing characteristic even when the area is increased, and it is easy to increase the rating of the current fuse 1.

That is, in the soluble conductor 6, the hole 10 is opened by the low-melting-point metal 4, and the deformation-restricting portion 9 covering the side surface 10a of the hole 10 with the second high-melting-point metal 11 is provided. When exposed to a high-temperature environment above the melting point of the low-melting-point metal 4 for a short time, the second high-melting-point metal 11 covering the side surface 10a of the hole 10 can be supported to suppress the flow of the molten low-melting-point metal 4 and constitute The first high-melting metal 5 in the outer layer. therefore, The soluble conductor 6 can suppress the molten low-melting-point metal 4 from aggregating and expanding due to tension, or the molten low-melting-point metal 4 flowing out and being thin, thereby emitting a situation of partial fragmentation or bulging.

Thereby, the soluble conductor 6 can prevent the resistance value from changing due to local crushing or bulging at the temperature such as solder connection, and can be maintained at a predetermined temperature or current for a predetermined period of time. Fusing characteristics. Further, as the soluble conductor 6, other surface-mounted components are reflow-mounted on the circuit board mounted on the current fuse 1, or the circuit board is reflow-mounted on another circuit board, etc., and repeatedly exposed to the reflow temperature. In this case, the deformation restricting portion 9 can suppress deformation, stabilize the fusing characteristic, and improve the mounting efficiency.

In addition, as described below, when the soluble conductor 6 is manufactured by cutting out from a large piece of chip, the low-melting metal 4 is exposed from the side surface of the soluble conductor 6, and the side surface contacts and engages through the connecting material 7 such as solder. Terminal 部 2. In this case, the soluble conductor 6 also suppresses the flow of the molten low-melting-point metal 4 by the deformation restricting portion 9; therefore, the melting point of the low-melting-point metal 4 will not be caused by drawing in the connecting material 7 such as molten solder from the side. The increase in volume causes a local decrease in resistance.

In addition, the soluble conductor 6 includes a deformation restricting portion 9, thereby suppressing undesired deformation of the low-melting-point metal 4 at the beginning of the module's thermal heating under an overcurrent during the melting stage. Therefore, the soluble conductor 6 can suppress deformation during heat generation by the deformation restricting portion 9 and stabilize the fusing characteristic.

[Through holes. Non-through hole]

Here, the hole 10 may be formed as a through hole penetrating the low melting point metal 4 in the thickness direction as shown in FIG. 2 (B), or may be formed as a non-through hole as shown in FIGS. 3 (A) and (B). When the hole 10 is formed as a through-hole, the second high-melting-point metal 11 covering the side surface 10 a of the hole 10 is continuous with the first high-melting-point metal 5 laminated on the front and back surfaces of the low-melting-point metal 4. In addition, the shape of the hole 10 is not particularly limited. In addition to a circle, the hole 10 may be a round shape, a rectangular shape or a square shape with corners curved.

When the hole 10 is formed as a non-through hole, as shown in FIG. 3 (A), the hole 10 is preferably covered with the second high-melting-point metal 11 to the bottom surface 10b. In the case where the soluble conductor 6 is formed as a non-through hole and the low-melting-point metal 4 is caused to flow by heating, the soluble conductor 6 can also be supported by the second high-melting-point metal 11 covering the side surface 10 a of the hole 10 and suppressed. Since the first high melting point metal 5 that flows and constitutes the outer layer, as shown in FIG. 3 (B), the thickness of the soluble conductor 6 varies slightly, and the fusing characteristics do not change.

[Filling of local melting point metals]

Moreover, the hole 10 may be filled with the second high melting point metal 11 as shown in FIGS. 4 (A) and 4 (B). By filling the holes 10 with the second high melting point metal 11, the soluble conductor 6 can increase the strength of the deformation restricting portion 9 supporting the first high melting point metal 5 constituting the outer layer, and further suppress the deformation of the soluble conductor 6, In addition, the rating can be increased by reducing the resistance.

As described below, the second high-melting-point metal 11 can be simultaneously formed when the first high-melting-point metal 5 is formed by electrolytic plating or the like, for example, the low-melting-point metal 4 provided with holes 10, and can be adjusted by aperture or plating. The second high-melting-point metal 11 is used to fill the hole 10 under the conditions.

[Section shape]

Further, as shown in FIG. 2 (B) or FIGS. 3 and 4, the hole 10 may be formed in a tapered cross section. The hole 10 can be formed by, for example, piercing a sharp body such as a needle into the low-melting-point metal 4 to form a tapered cross-section according to the shape of the sharp body. Further, as shown in FIGS. 5 (A) and (B), the hole 10 may be formed in a rectangular cross section. The soluble conductor 6 can be formed with a rectangular cross-section hole 10 by, for example, pressing the low-melting-point metal 4 using a mold corresponding to the rectangular cross-section hole 10.

[Partial coverage of high melting point metals]

Furthermore, in the case of the deformation restricting portion 9, as long as at least a part of the side surface 10a of the hole 10 is contacted with The first high-melting-point metal 5 may be continuously covered by the second high-melting-point metal 11. As shown in FIG. 6, the second high-melting-point metal 11 may be covered on the upper side of the side surface 10 a. Further, the deformation restricting portion 9 may be formed or penetrated by forming a laminated body of the low-melting-point metal 4 and the first high-melting-point metal 5 by penetrating the sharp body from the first high-melting-point metal 5. In addition, a part of the first high-melting-point metal 5 is pushed into the side surface 10 a of the hole 10 to serve as the second high-melting-point metal 11.

As shown in FIG. 6, the second high-melting metal 11 that is continuous with the first high-melting metal 5 is partially laminated with a part of the open end side of the side 10 a of the hole 10, and the second high-melting metal 11 can also be used for the second high The melting point metal 11 suppresses the flow of the molten low melting point metal 4 and can support the first high melting point metal 5 on the open end side, thereby suppressing the occurrence of local fragmentation or expansion of the soluble conductor 6.

Further, as shown in FIG. 7 (A), the deformation restricting portion 9 may form the hole 10 as a non-through hole and be formed on one surface and the other surface of the low-melting metal 4 so as to face each other. Further, as shown in FIG. 7 (B), the deformation restricting portion may also form the hole 10 as a non-through hole, and may be formed on one surface and the other surface of the low-melting metal 4 so as not to face each other. By forming the non-penetrating holes 10 on the two sides of the low-melting metal 4 or facing each other, the molten low-melting metal can also be suppressed by the second high-melting metal 11 covering the side surface 10 a of each hole 10. 4 flows and supports the first refractory metal 5 constituting the outer layer. Therefore, the soluble conductor 6 can suppress the molten low-melting-point metal 4 from aggregating and expanding due to tension, or the molten low-melting-point metal 4 flowing out and becoming thin, thereby causing local fragmentation or bulging.

Furthermore, the deformation restricting portion 9 is provided with a hole diameter through which the plating solution can flow in so that the second high-melting-point metal 11 covers the side surface 10a of the hole 10 by electrolytic plating. This aspect is preferable in terms of manufacturing efficiency. The minimum diameter is 50 μm or more, and more preferably 70 to 80 μm. Furthermore, The maximum diameter of the hole 10 can be appropriately set in consideration of the relationship with the plating limit of the second high-melting metal 11 and the thickness of the soluble conductor 6, but if the hole diameter is large, the initial resistance value tends to increase.

In addition, it is preferable that the depth of the deformation restricting portion 9 is 50% or more of the thickness of the low-melting-point metal 4. If the depth of the hole 10 is shallower than the above value, the flow of the molten low-melting metal 4 cannot be suppressed, and the melting characteristics may be changed as the soluble conductor 6 is deformed.

In addition, the deformation restricting portion 9 is preferably formed so that the holes 10 formed in the low-melting-point metal 4 have a predetermined density, for example, a density of 1 or more per 15 × 15 mm.

Further, it is preferable that the deformation restricting portion 9 is such that the hole 10 is formed at a portion where the soluble conductor 6 is fused when an overcurrent is generated. The fused portion of the soluble conductor 6 is not supported by one of the current fuses 1 to the engaging terminal portion 2 but a relatively low rigidity portion. Therefore, the portion is likely to be deformed by the flow of the low-melting metal 4 at this portion. Therefore, by opening holes 10 in the fusible portion of the soluble conductor 6 and covering the side surface 10a with the second high melting point metal 11, the flow of the low melting point metal 4 in the fused portion can be suppressed and deformation can be prevented.

In addition, it is preferable that the deformation restricting portion 9 is provided with the hole 10 at least in a central portion of the soluble conductor 6. Both ends of the soluble conductor 6 are supported by a pair of engaging terminal portions 2. The central portion, which is the farthest away from the outer periphery, has the lowest rigidity, so it is easy to deform. Therefore, since the central portion of the soluble conductor 6 is provided with the hole 10 whose side surface 10a is covered by the second high-melting-point metal 11, the rigidity of the central portion can be improved, and deformation can be effectively prevented.

In addition, the deformation restricting portion 9 may set the number difference or density difference of the holes 10 on both sides of the line passing through the center of the soluble conductor 6 to 50% or less. That is, the deformation restricting portion 9 is a plurality of holes 10 dispersedly arranged in the soluble conductor 6, and the effect of the deformation restricting portion 9 is applied to the entire surface of the soluble conductor 6 approximately uniformly. The number of sides of the center line is different or dense The degree difference is within 50%. For example, when the three holes 10 are evenly arranged on the entire surface of the soluble conductor 6 in a manner of being balanced by 3 points of support, the number of holes 10 passing through the center of the soluble conductor 6 on both sides is different, or The density difference becomes 50%. By making the number difference or density difference of the holes 10 on both sides of the line passing through the center of the fuse element 50% or less, the rigidity of the soluble conductor 6 as a whole can be improved, thereby effectively preventing deformation.

[Manufacturing method of soluble conductor]

The soluble conductor 6 can be manufactured by forming a hole 10 constituting the deformation restricting portion 9 by the low-melting-point metal 4 and forming a high-melting-point metal on the low-melting-point metal 4 using a plating technique. The soluble conductor 6 is manufactured by, for example, opening a predetermined hole 10 in a long solder foil, and then performing Ag plating on the surface to produce a strip-shaped element. When used, it can be efficiently manufactured by cutting according to size. And easy to use.

Here, in the conventional soluble conductor composed only of a laminated structure of a low melting point metal and a high melting point metal, the connection material 7 such as solder may flow in from a cut surface or the low melting point metal 4 may flow out. In order to avoid the contact between the cut surface and the connecting material 7, it is necessary to study processing such as bending both ends, which may result in an increase in manufacturing man-hours or hinder the miniaturization of the current fuse 1.

In this regard, as for the soluble conductor 6, even if the low-melting-point metal 4 is exposed from the cut surface, the flow of the molten low-melting-point metal 4 can be suppressed by the deformation restricting portion 9, and thus the self-cutting of the connecting material 7 can be suppressed. The inflow of the cross section or the outflow of the low-melting-point metal 4 can prevent variations in the resistance value and variations in the fusing characteristics caused by variations in thickness. Therefore, it is not necessary to perform the process of bending both exposed ends of the cut surface, so that it is possible to improve the manufacturing efficiency or miniaturize the current fuse 1.

The soluble conductor 6 is formed by using a thin film forming technique such as vapor deposition, or Other well-known lamination techniques can also form a soluble conductor 6 laminated with a low melting point metal 4 and a first high melting point metal 5.

In addition, the soluble conductor 6 may form an anti-oxidation film (not shown) on the surface of the first refractory metal 5 constituting the outer layer. The first high-melting-point metal 5 in the outer layer of the soluble conductor 6 is further covered with an anti-oxidation film, thereby preventing the oxidation of Cu even when a Cu plating layer is formed as the first high-melting-point metal 5, for example. Therefore, the soluble conductor 6 can prevent the melting time from being increased due to the oxidation of Cu, and can be melted in a short time.

In the soluble conductor 6, as the first high-melting-point metal 5, a metal that is economical but easily oxidizable, such as Cu, can be used, and can be formed without using an expensive material such as Ag.

The anti-oxidation film of the first high-melting-point metal 5 can be made of the same material as the low-melting-point metal 4, for example, a Pb-free solder whose main component is Sn can be used. Further, the anti-oxidation film can be formed by performing tin plating on the surface of the first refractory metal 5. In addition, the anti-oxidation film may be formed by Au plating or pre-flux.

[Flaky element]

Moreover, the soluble conductor 6 can also be cut out from a large sheet-like element in a desired size. That is, it is also possible to form a large sheet-like element composed of a laminate of a low-melting-point metal 4 and a first high-melting-point metal 5 in which deformation restricting portions 9 are formed uniformly over the entire surface, and a plurality of soluble conductors of any size can be cut out 6, thereby forming a soluble conductor 6. In the soluble conductor 6 cut out from the sheet-like element, the deformation restricting portion 9 is formed uniformly over the entire surface. Therefore, even if the low melting point metal 4 is exposed from the cut surface, the deformation restricting portion 9 can suppress the low melting. The flow of the melting point metal 4 can prevent the inflow of the connecting material 7 such as solder from the cut surface or the outflow of the low melting point metal 4, and can prevent variations in the resistance value and variations in the melting characteristics due to thickness variations.

In addition, after the predetermined holes 10 are formed in the long-shaped solder foil, electrolytic plating is performed on the surface to manufacture a strip-shaped element and cut it to a predetermined length. The size of the soluble conductor 6 It is the width of the band-shaped element, and the band-shaped element must be manufactured according to each size.

However, by forming a large sheet-like element, the soluble conductor 6 can be cut out in a desired size, thereby increasing the degree of freedom in size.

In addition, if electrolytic plating is performed on the long-shaped solder foil, the first high-melting-point metal 5 is thickly plated on the side edge portion in the longitudinal direction where the electric field is concentrated, and it is difficult to obtain the soluble conductor 6 having a uniform thickness. Therefore, in the current fuse 1, the fusing characteristic is changed due to the arrangement of the thick-walled portion of the soluble conductor 6, and therefore, the arrangement is also restricted.

However, by forming a large sheet-like element, the soluble conductor 6 can be cut away from the thick-walled portion, and the soluble conductor 6 having a uniform thickness over the entire surface can be obtained. Therefore, the fusing characteristic of the soluble conductor 6 cut out from the sheet-shaped element does not change according to the configuration, and the degree of freedom of the configuration is high, so that the fusing characteristic can be stabilized.

[High melting point particles]

In addition, as shown in FIG. 8, the soluble conductor 6 may include the first high-melting-point particle 13 having a melting point higher than that of the low-melting metal 4 and the low-melting metal 4 to form a deformation restricting portion 9. The first high-melting-point particle 13 is a substance having a high melting point that does not melt even at the solder joint temperature. For example, a metal such as Cu, Ag, Ni, or an alloy containing these particles, glass particles, or ceramic particles can be used. Wait. The first high-melting-point particles 13 may have any shape such as a spherical shape and a scaly shape. In addition, when the first high-melting-point particle 13 is made of a metal or an alloy, the specific gravity is higher than that of glass or ceramic, so it has good adaptability and excellent dispersibility.

The deformation restricting portion 9 can be formed by mixing the first high-melting-point particles 13 with a low-melting-point metal material, and then forming the ribbon into a band-like shape to form a low level in which the first high-melting-point particles 13 are dispersedly arranged in a single layer. The melting point metal 4 is then laminated with the first refractory metal 5. In addition, the deformation restricting portion 9 may press the soluble conductor 6 in the thickness direction after laminating the first high-melting-point metal 5, so that the first high-melting-point particles 13 are in close contact with the first high-melting-point metal 5. Accordingly, in the deformation restricting portion 9, the first high-melting-point metal 5 is supported by the first high-melting-point particles 13. When the low-melting-point metal 4 is melted by heating, the first high-melting-point particles 13 can also be suppressed by the first high-melting point particles 13. It flows and supports the first high-melting-point metal 5, so that the occurrence of local fragmentation or expansion of the soluble conductor 6 can be suppressed.

Moreover, as shown in FIG. 9 (A), the deformation restricting portion 9 may mix the first high-melting-point particles 13 having a particle diameter smaller than the thickness of the low-melting-point metal 4 to the low-melting-point metal 4. In this case, as shown in FIG. 9 (B), the deformation restricting portion 9 can also suppress the flow of the molten low-melting metal 4 and support the first high-melting metal 5 by the first high-melting particles 13, thereby suppressing the Partial fragmentation or swelling of the molten conductor 6 occurs.

In addition, as shown in FIG. 10, the soluble conductor 6 may press the second high melting point particles 15 having a higher melting point than the low melting point metal 4 into the low melting point metal 4 to form the deformation restricting portion 9. As the second high-melting-point particle 15, the same material as the first high-melting-point particle 13 can be used.

The deformation restricting portion 9 is formed by pressing the second high-melting-point particles 15 into the low-melting-point metal 4 and then laminating the first high-melting-point metal 5. At this time, it is preferable that the second high melting point particles 15 penetrate the low melting point metal 4 in the thickness direction. With this, in the deformation restricting portion 9, the first high-melting-point metal 5 is supported by the second high-melting-point particles 15, and when the low-melting-point metal 4 is melted by heating, the low-melting-point can be suppressed by the second high-melting-point particles 15. The flow of the metal 4 supports the first high-melting-point metal 5, so that the local breakage or expansion of the soluble conductor 6 can be suppressed.

In addition, as shown in FIG. 11, the soluble conductor 6 may be formed by pressing the second high melting point particles 15 having a higher melting point than the low melting point metal 4 into the first high melting point metal 5 and the low melting point metal 4 to form a deformation restricting portion. 9.

The deformation restricting portion 9 can be formed by pressing the second high-melting-point particles 15 into a laminate of the low-melting-point metal 4 and the first high-melting-point metal 5 and burying them in the low-melting-point metal 4. At this time, it is preferable that the second high melting point particles 15 penetrate the low melting point metal 4 and the first high melting point metal 5 in the thickness direction. With this, in the deformation restricting portion 9, the first high-melting metal 5 is supported by the second high-melting particles 15, and when the low-melting metal 4 is melted by heating, the second high-melting particles 15 can also suppress the low-melting metal 4 The first high-melting-point metal 5 flows and supports, so that the occurrence of local fragmentation or expansion of the soluble conductor 6 can be suppressed.

In addition, the deformation restricting portion 9 may be formed by forming a hole 10 in the low-melting metal 4 and laminating the second high-melting metal 11, and further inserting the second high-melting particle 15 into the hole 10.

局部破碎或膨脹之發生。 Further, as shown in FIG. 12, the deformation restricting portion 9 may be provided with a flange portion 16 bonded to the first high melting point metal 5 on the second high melting point particles 15. The flange portion 16 can, for example, press the first high-melting-point particles 13 into the first high-melting-point metal 5 and the low-melting-point metal 4, and then press the soluble conductor 6 in the thickness direction to make the second high-melting point particles 15. The two ends melted and formed. This allows the first high-melting-point metal 5 to be strongly supported by joining with the flange portion 16 of the second high-melting-point particle 15 in the deformation restricting portion 9. When the low-melting-point metal 4 is melted by heating, the The second high-melting-point particles 15 suppress the flow of the low-melting-point metal 4, and the first high-melting-point metal 5 is supported by the flange portion 16, so that the soluble conductor 6 can be further suppressed.

Local fragmentation or swelling occurs.

[Modification 1]

In addition, as shown in FIGS. 13 (A) and (B), the deformation restricting portion 9 may be provided on the low-melting-point metal 4. One or a plurality of grooves 17 are provided, and at least a part of the side surface 17 a of the groove 17 is covered with a second high-melting metal 11 continuous with the first high-melting metal 5. The groove 17 can be formed by, for example, pressing the low-melting-point metal 4 using a mold. Further, the grooves 17 may be formed along the current-carrying direction of the soluble conductor 6 as shown in FIG. 13 (A), or may be formed along a direction orthogonal or oblique to the current-carrying direction.

The deformation restricting portion 9 formed by the groove 17 covered by the second high-melting-point metal 11 can also suppress the flow of the molten low-melting-point metal 4 and prevent the local conductor 6 from being broken or bulged, thereby stabilizing the melting characteristics. Into.

[Modification 2]

The current fuse 1 is formed by the soluble conductor 6 constituting the fuse portion 3, and the soluble conductor 6 is connected between the engaging terminal portions 2. However, the current fuse of the present invention may also be applied. As shown in FIGS. 14 (A) and 14 (B), a pair of the engagement terminal portion 2 and the fuse portion 3 are formed by the soluble conductor 6. The current fuse 20 shown in FIG. 14 can be formed by, for example, pressing a low-melting-point metal 4 such as a solder foil to integrally form a pair of engaging terminal portions 2 and a fuse portion 3, and thereafter implementing Ag Plating.

The engaging terminal portion 2 of the current fuse 20 is engaged with the terminal portion of the electrical circuit, and is joined by, for example, a bolt or a screw, thereby making the resistance lower than that of the fuse portion 3 and reducing the electrical resistance. Due to the heat dissipation of the terminal portion of the electrical circuit, the engaging terminal portion 2 is cooled. Therefore, if an overcurrent flows, the fuse portion 3 will blow.

Further, as shown in FIGS. 15 (A) and (B), the current fuse 20 may be provided with the above-mentioned deformation restricting portion 9 on the soluble conductor 6. The deformation restricting portion 9 provided in the current fuse 20 includes various modification examples similar to the deformation restricting portion 9 formed in the current fuse 1. By providing the deformation restricting portion 9 The soluble conductor 6 forms the engaging terminal portion 2. When the engaging terminal portion 2 is connected to the circuit board by a bolt or a screw, the deformation due to the screw tightening pressure can be suppressed, and the resistance value or the melting time can be suppressed. Changes, and can stabilize the fusing characteristics.

In addition, in the current fuse 20, the engagement terminal portion 2 and the fuse portion 3 are integrally formed by the soluble conductor 6. Therefore, the melting temperature of the soluble conductor 6 is relatively low, for example, about 300 ° C. The temperature of the engaging terminal portion 2 is suppressed to be low, and it is not necessary to locally narrow the fuse portion 3 as a countermeasure against the overheating of the engaging terminal portion 2, and it is easy to cope with a large current under a low resistance. Furthermore, in the current fuse 20, the width of the fuse portion can be adjusted in order to adjust the resistance value.

Furthermore, the current fuse 20 can be formed by forming a laminated body of the low-melting-point metal 4 and the first high-melting-point metal 5 and then punching it into a predetermined fuse shape as shown in FIG. 14 or FIG. 15. 4 is exposed from the cut surface. Therefore, in terms of the construction method, it is preferable to form the deformation restricting portion 9 as shown in FIG. 15.

1‧‧‧current fuse

2‧‧‧ Engagement terminal

3‧‧‧Fuse

4‧‧‧Lead-free low melting point metal

5‧‧‧Lead-free first high melting point metal

6‧‧‧ soluble conductor

7‧‧‧Connecting material

Claims (18)

A current fuse includes: two engagement terminal portions; and a fuse portion provided between the engagement terminal portions; the fuse portion is formed by laminating a low melting point metal and a first higher melting point than the low melting point metal; A soluble conductor of a melting metal is formed. For example, the current fuse of the first scope of the patent application, wherein the soluble conductor and the two engaging terminal portions are connected through a connection medium. For example, the current fuse of the second scope of the application for a patent, wherein the connection medium is solder. For example, the current fuse of the scope of application for a patent, wherein the soluble conductor and the two engaging terminal portions are connected by welding. For example, the current fuse of the first patent application range, wherein the engaging terminal portion and the fuse portion are formed by the soluble conductor. For example, the current fuse according to any one of claims 1 to 5, wherein the above-mentioned soluble conductive system has a layered body of the above-mentioned first high-melting-point metal at least on both the front and back areas of the low-melting-point metal. For example, in the current fuse of any one of claims 1 to 5, the volume of the low-melting-point metal in the soluble conductor is greater than the volume of the first high-melting-point metal. For example, the current fuse according to any one of claims 1 to 5, wherein the low-melting-point metal is Sn or an alloy whose main component is Sn, and the first high-melting-point metal is Ag or Cu or whose main component is Ag or Cu alloy. For example, the current fuse of any one of claims 1 to 5, wherein The conductor is provided with a deformation restricting portion that restricts deformation. For example, the current fuse of the ninth scope of the patent application, wherein the deformation restricting portion is such that at least a part of the side surface of one or more holes provided in the low melting point metal is continuous with the second high continuously with the first high melting point metal. Melting metal overlay. For example, the current fuse of the scope of application for patent No. 10, wherein the hole is a through hole or a non-through hole. For example, the current fuse of the scope of application for the patent No. 10 or 11, wherein the hole is filled with the second high melting point metal. For example, the current fuse of the scope of application for patent No. 10, wherein the shape of the hole is a circle, a circle, a rectangle with a corner corner, or a square. For example, in the current fuse of the ninth scope of the patent application, the deformation restricting portion is formed by blending first high melting point particles having a higher melting point than the low melting point metal with the low melting point metal. For example, the current fuse of the ninth scope of the patent application, wherein the deformation restricting portion is formed by pressing second high melting point particles having a melting point higher than the low melting point metal into the low melting point metal. For example, in the current fuse of the ninth scope of the application for patent, the deformation restricting part is a second high melting point particle having a melting point higher than the low melting point metal and is pressed into the laminated body of the first high melting point metal and the low melting point metal. to make. For example, in the current fuse of the ninth scope of the patent application, the deformation limiting portion is connected between the soluble conductor and the engaging terminal portion, and the flow of the low-melting-point metal that is melted by the soluble conductor is suppressed, and The above-mentioned soluble conductor is deformed and the resistance value is changed. For example, in the current fuse of the ninth scope of the patent application, the deformation restricting portion suppresses the pressure caused by the screw tightening pressure of the two engaging terminal portions formed on one of the soluble conductors. Deformation.