WO2016009988A1

WO2016009988A1 - Chip fuse and fuse element

Info

Publication number: WO2016009988A1
Application number: PCT/JP2015/070032
Authority: WO
Inventors: 吉弘米田
Original assignee: デクセリアルズ株式会社
Priority date: 2014-07-15
Filing date: 2015-07-13
Publication date: 2016-01-21
Also published as: CN106663574B; JP2016021329A; KR102368741B1; TWI685872B; TW201611071A; CN106663574A; JP6491431B2; KR20170032225A

Abstract

Provided are a chip fuse and a fuse element, whereof the ability to blow fast and the ability to insulate after blowing are excellent even if the size of the chip fuse is to be reduced. The chip fuse comprises: an insulating substrate (2); a fuse element (5) mounted on the insulating substrate (2) and having a plurality of parallel element parts (7), which, through self-heating due to the passage of a rate-exceeding current, are blown, shutting the electrical path; and insulation parts (8), each provided in between the plurality of element parts (7), for preventing the parallel elements parts (7) from establishing connection with each other.

Description

Fuse element and fuse element

TECHNICAL FIELD The present invention relates to a fuse element and a fuse element that are mounted on a current path and blown by self-heating when a current exceeding a rating flows, and the current element path is cut off. The present invention relates to an element and a fuse element.
This application claims priority on the basis of Japanese Patent Application No. 2014-144705 filed on July 15, 2014 in Japan. This application is incorporated herein by reference. Incorporated.

Conventionally, a fuse element that melts by self-heating when a current exceeding the rating flows and interrupts the current path has been used. As the fuse element, for example, a holder-fixed fuse in which solder is enclosed in a glass tube, a chip fuse in which an Ag electrode is printed on the surface of a ceramic substrate, or a screw fixing in which a part of a copper electrode is thinned and incorporated in a plastic case or Plug-in fuses are often used.

JP 2011-82064 A

However, it has been pointed out that the above-mentioned existing fuse elements cannot be surface-mounted by reflow, have a low current rating, and if the rating is increased by increasing the size, the quick disconnection property is inferior.

In addition, when assuming a fast-acting fuse element for reflow mounting, generally, a high melting point solder containing Pb having a melting point of 300 ° C. or higher is preferable for the fuse element in terms of fusing characteristics so as not to melt by the heat of reflow. However, in the RoHS directive and the like, the use of Pb-containing solder is only limitedly recognized, and it is considered that the demand for Pb-free solder will increase in the future.

In other words, the fuse element can be surface-mounted by reflow and has excellent mountability to the fuse element, it can handle a large current by raising its rating, and the current path is quickly interrupted when overcurrent exceeds the rating. It is required to have fast fusing properties.

In order to meet such requirements, a fuse element in which a plurality of element portions are arranged in parallel has also been proposed. As shown in FIG. 14A, the fuse element 50 has a plurality of energization paths by arranging a plurality of element portions 51A to 51C in parallel. The plurality of element portions 51A to 51C are connected across the first and

second electrodes

53 and 54 formed on the surface 52a of the insulating substrate 52, respectively, and serve as current energization paths. By doing so, it melts by self-heating (Joule heat). The fuse element 50 cuts off the current path between the first and

second electrodes

53 and 54 by melting all the element portions 51A to 51C.

At this time, when a current exceeding the rating is supplied to the fuse element 50, a large amount of current flows through the element portion 51 having a low resistance value, and the fuse element 50 is melted sequentially by self-heating, and finally the remaining element portion 51. Arc discharge occurs only when the melts. Therefore, according to the fuse element 50, even when an arc discharge occurs when the last remaining element portion 51 is melted, the fuse element 50 becomes a small scale according to the volume of the element portion 51, and explosive scattering of the molten metal is caused. In addition, the insulation after fusing can be improved. Further, since the fuse element 50 is blown for each of the plurality of element portions 51A to 51C, less heat energy is required for fusing each element portion 51 and can be cut off in a short time.

However, in the fuse element 50, when the interval between the element portions 51A to 51C arranged in parallel with the miniaturization of the fuse element becomes close, as shown in FIG. When a large amount of current flows through the element portion 51 having a low resistance value to generate heat, the element portion 51 may be partially melted by heat generation and may contact the adjacent element portion 51. When adjacent element parts 51 come into contact with each other, the element part 51 becomes large, and the element parts 51A to 51C cannot be melted sequentially, and the entire element part 51 is melted as shown in FIG. Therefore, since the electric power required until fusing increases, the current path cannot be cut off quickly. In addition, when the element portion 51 is enlarged, arc discharge generated at the time of fusing becomes large-scale, and there is a possibility that the insulation after fusing may be impaired due to explosive scattering of molten metal.

Therefore, an object of the present invention is to provide a fuse element and a fuse element that are excellent in quick fusing property and insulation after fusing, even in a fuse element that is downsized.

In order to solve the above-described problem, a fuse element according to the present invention is mounted on an insulating substrate and the insulating substrate, and in parallel, the current exceeding the rating is blown by self-heating to cut off the energization path. A fuse element having a plurality of element parts, or a plurality of parallel fuse elements, and a plurality of the element parts or the fuse elements provided in parallel between the plurality of element parts or the plurality of fuse elements. And an insulating part for preventing connection.

The fuse element according to the present invention includes a plurality of element portions arranged in parallel and an insulating portion provided between the plurality of element portions to prevent connection between the element portions arranged in parallel. The part melts due to self-heating due to energization with a current exceeding the rating.

According to the present invention, by providing the insulating portion, the fuse element is prevented from melting and expanding due to its own heat generation and coming into contact with adjacent element portions and agglomerating when the element portions are sequentially melted. The As a result, the fuse element increases in size by melting and aggregating adjacent element parts, increasing the fusing time due to the increase in power required for fusing, and molten metal due to the large scale of arc discharge that occurs during fusing It is possible to prevent the explosive splashing and the insulation deterioration after fusing.

1A and 1B are diagrams showing an example of a fuse element to which the present invention is applied. FIG. 1A is an exploded perspective view with a cover member removed, and FIG. 1B is an external perspective view. 2A and 2B are diagrams showing the fusing order of the fuse elements, where FIG. 2A shows a state before fusing, FIG. 2B shows a state in which an outer element portion is blown, and FIG. 2C shows a state in which all element portions are blown. FIGS. 3A and 3B are diagrams showing a fusing state of a fuse element using a single plate-like element, in which FIG. 3A shows a state in which a current exceeding the rating starts to be applied, and FIG. 3B shows a state in which the element has melted and aggregated (C) shows a state in which the element is blown out explosively with arc discharge. FIG. 4 is a cross-sectional view of a fuse element in which an insulating portion is provided on the surface of an insulating substrate. FIG. 5 is a cross-sectional view of a fuse element in which an insulating portion is provided on the top surface of the cover member. FIG. 6 is a cross-sectional view of a fuse element in which an insulating portion is provided by filling and hardening a material constituting the insulating portion between element portions. FIGS. 7A and 7B are plan views showing the fuse element. FIG. 7A is a view in which both sides of the element portion are integrally supported, and FIG. 7B is a view in which one side of the element portion is integrally supported. FIG. 8 is a perspective view showing a fuse element in which three elements are arranged in parallel. 9A and 9B are diagrams showing a manufacturing process of a fuse element using the fuse element shown in FIG. 1, wherein FIG. 9A is a perspective view of the insulating substrate, FIG. 9B is a state in which the fuse element is mounted on the insulating substrate, and FIG. ) Is a state in which a flux is provided on the fuse element, (D) is a state in which a cover member is mounted, and (E) is a state of mounting on a circuit board. 10A and 10B are diagrams showing a fuse element in which an overhang portion is provided on the first and second electrodes. FIG. 10A is a plan view of an insulating substrate, and FIG. 10B is a perspective view. FIG. 11 is a diagram showing a manufacturing process of another fuse element using the fuse element shown in FIG. 1, (A) is a perspective view of the insulating substrate, (B) is a state in which the fuse element is mounted on the insulating substrate, (C) shows a state where flux is provided on the fuse element, and (D) shows a state where a cover member is mounted and a state where the cover member is mounted on the circuit board. FIG. 12 is a perspective view showing another fuse element using another fuse element. FIG. 13 is a plan view showing an insulating substrate on which first and second divided electrodes are formed. 14A and 14B are diagrams showing a fusing state of a fuse element according to a reference example, in which FIG. 14A is a state before fusing, FIG. 14B is a state in which an outer element portion is melted and integrated with an inner element portion, and FIG. Indicates a state in which all the element portions are fused at the same time.

Hereinafter, a fuse element and a fuse element to which the present invention is applied will be described in detail with reference to the drawings. It should be noted that the present invention is not limited to the following embodiments, and various modifications can be made without departing from the scope of the present invention. Further, the drawings are schematic, and the ratio of each dimension may be different from the actual one. Specific dimensions should be determined in consideration of the following description. Moreover, it is a matter of course that portions having different dimensional relationships and ratios are included between the drawings.

[First embodiment]
As shown in FIGS. 1A and 1B, the fuse element 1 according to the present invention includes an insulating substrate 2, first and

second electrodes

3 and 4 provided on the insulating substrate 2, and first and second electrodes. A fuse element 5 that is mounted between two

electrodes

3 and 4, is blown by self-heating when a current exceeding the rating is applied, and interrupts a current path between the first electrode 3 and the second electrode 4; And a cover member 6 covering the surface 2a of the insulating substrate 2 on which the fuse element 5 is provided.

Further, a plurality of element portions 7 are arranged in parallel with the fuse element 5, and an insulating portion 8 for preventing connection between the parallel element portions 7 is provided between the plurality of element portions 7. When the fuse element 1 is mounted on a circuit board, the fuse element 5 is incorporated in series with a circuit formed on the circuit board.

The fuse element 1 realizes a small and highly rated fuse element. For example, although the dimensions of the insulating substrate 2 are as small as 3 to 4 mm × 5 to 6 mm, the resistance value is 0.5 to 1 mΩ, 50-60A rating and higher rating are being achieved. Of course, the present invention can be applied to fuse elements having all sizes, resistance values, and current ratings.

The insulating substrate 2 is formed in a square shape by an insulating member such as alumina, glass ceramics, mullite, zirconia. In addition, the insulating substrate 2 may be made of a material used for a printed wiring board such as a glass epoxy board or a phenol board.

First and

second electrodes

3 and 4 are formed at opposite ends of the insulating substrate. The first and

second electrodes

3 and 4 are each formed by a conductive pattern such as Cu or Ag wiring, and in the case of a wiring material such as Cu that is easily oxidized, the surface is appropriately protected with Sn plating or the like as an anti-oxidation measure. A layer is provided.

[Cover member]
The fuse element 1 has a cover member 6 mounted on the surface 2a of the insulating substrate 2 to protect the inside and prevent the molten fuse element 5 from scattering. The cover member 6 has a side wall 6 a mounted on the surface 2 a of the insulating substrate 2 and a top surface 6 b constituting the upper surface of the fuse element 1. When the side wall 6a of the cover member 6 is connected to the surface 2a of the insulating substrate 2, the fuse element 1 has terminal portions provided at both ends of the fuse element 5 from between the surface 2a of the insulating substrate 2 and the top surface 6b. A gap leading out 10 is provided. The cover member 6 can be formed using an insulating member such as a thermoplastic plastic, a ceramic, a glass epoxy substrate, or the like.

[Fuse element]
The fuse element 5 mounted between the first and

second electrodes

3 and 4 is melted by self-heating (Joule heat) when a current exceeding the rating is applied, and the first electrode 3 and the second electrode The current path to 4 is cut off. The fuse element 5 is mounted between the first and

second electrodes

3 and 4 via a connecting material such as solder and then connected to the insulating substrate 2 by reflow soldering or the like.

The fuse element 5 is connected to a plurality of element portions 7 mounted between the first and

second electrodes

3 and 4 formed on the insulating substrate 2 and connection terminals of a circuit board on which the fuse element 1 is mounted. Terminal portion 10.

Hereinafter, a case where the fuse element 5 in which the three element portions 7A to 7C are arranged in parallel will be described as an example. As shown in FIG. 2A, each of the element portions 7A to 7C is mounted between the first and

second electrodes

3 and 4 formed on the insulating substrate 2, so that a plurality of energizations of the fuse element 5 are performed. Configure the route. Then, as shown in FIG. 2B, the plurality of element portions 7A to 7C are fused by self-heating (Joule heat) when a current exceeding the rating is applied. The fuse element 5 cuts off the current path between the first and

second electrodes

3 and 4 by melting all of the element portions 7A to 7C (FIG. 2C).

In addition, the fuse element 5 is blown over a wide range even when arc discharge occurs when a current exceeding the rating is applied and melted, and a new current path is formed by the scattered metal. Alternatively, it is possible to prevent the scattered metal from adhering to the terminals and surrounding electronic components.

That is, as shown in FIG. 3A, in the fuse element 43 mounted over a wide range between the

electrode terminals

41 and 42 on the insulating substrate 40, when a voltage exceeding the rating is applied and a large current flows, Fever. Then, as shown in FIG. 3B, the fuse element 43 is melted and aggregated, and then melted while large-scale arc discharge is generated as shown in FIG. 3C. . For this reason, the melt of the fuse element 43 explodes. For this reason, a new current path is formed by the scattered metal and the insulation is impaired, or the

electrode terminals

41 and 42 formed on the insulating substrate 40 are melted and scattered together to adhere to surrounding electronic components and the like. There is a fear. Furthermore, since the fuse element 43 is melted and cut off after agglomeration as a whole, the heat energy required for fusing increases and the fast fusing property is poor.

Current countermeasures to quickly stop arc discharge and shut off the circuit include a hollow case filled with an arc extinguishing material, or a high voltage compatible current that generates a time lag by spirally wrapping a fuse element around the heat dissipation material Fuses have also been proposed. However, conventional high-voltage current fuses require complicated materials and processing processes, such as arc-quenching material encapsulation and spiral fuse manufacturing, and the fuse element is downsized and current rating is increased. It is disadvantageous in terms.

In this respect, the fuse element 5 has a plurality of element portions 7A to 7C mounted between the first and

second electrodes

3 and 4 in parallel. A large amount of current flows through the lower element portion 7 and is melted sequentially by self-heating, and arc discharge occurs only when the last remaining element portion 7 is melted. Therefore, according to the fuse element 5, even when an arc discharge occurs when the last remaining element portion 7 is melted, the size of the fuse element 5 becomes small according to the volume of the element portion 7, and the explosive scattering of the molten metal is prevented. In addition, the insulation after fusing can be greatly improved. Further, since the fuse element 5 is blown for each of the plurality of element portions 7A to 7C, less heat energy is required for fusing each element portion 7 and can be cut off in a short time.

[Insulation part]
As shown in FIGS. 1 and 4, the fuse element 1 is provided with an insulating portion 8 between the plurality of element portions 7 to prevent connection between the element portions 7 arranged in parallel. By providing the insulating portion 8, the fuse element 5 prevents the element portion 7 from melting and expanding due to its own heat generation and coming into contact with the adjacent element portion 7 and agglomerating when the element portion 7 is sequentially melted. As a result, the fuse element 5 is increased in size by melting and agglomerating adjacent element portions 7, and due to an increase in fusing time due to an increase in power required for fusing and an increase in the scale of arc discharge generated at the time of fusing. It is possible to prevent explosive scattering of molten metal and a decrease in insulation after fusing.

The insulating portion 8 is erected by, for example, printing an insulating material such as solder resist or glass on the surface 2a of the insulating substrate 2. Further, since the insulating portion 8 has insulating properties, it does not have wettability with respect to the melting element, and therefore it is not always necessary to completely isolate the adjacent element portions 7 from each other. That is, even if there is a gap with the top surface 6b of the cover member 6, the pulling action due to wettability does not work, and the molten element does not flow from the gap to the side of the element portion arranged in parallel. Further, when the element portion 7 is melted by its own heat generation, the element portion 7 swells in a dome shape in the region between the first and

second electrodes

3 and 4. Therefore, if the insulating part 8 has a height that is more than half of the height from the surface 2a of the insulating substrate 2 to the top surface 6b of the cover member 6, the molten element is prevented from coming into contact with the element parts 7 arranged in parallel. it can. Of course, the insulating portion 8 may be formed at a height from the surface 2a of the insulating substrate 2 to the top surface 6b of the cover member 6 to isolate the element portions 7 from each other.

Further, as shown in FIG. 5, the insulating portion 8 may be formed on the top surface 6 b of the cover member 6. The insulating portion 8 may be integrally formed on the top surface 6b of the cover member 6, or may be erected by printing an insulating material such as solder resist or glass on the top surface 6b. Also in this case, if the insulating portion 8 has a height that is more than half of the height from the top surface 6b of the cover member 6 to the surface 2a of the insulating substrate 2, the insulating element 8 is in contact with the element portions 7 in parallel. Can be prevented.

In addition, as shown in FIG. 6, the insulating portion 8 is provided on the insulating substrate 2 and the cover member 6, and a liquid or paste-like insulating material constituting the insulating portion 8 is applied between a plurality of element portions 7 arranged in parallel. And may be formed by curing. As an insulating material constituting the insulating portion 8, a thermosetting insulating adhesive such as an epoxy resin, a solder resist, or a glass paste can be used. In this case, the insulating material constituting the insulating portion 8 may be applied and cured after the fuse element 5 is connected to the insulating substrate 2, or may be applied and cured before the fuse element 5 is connected to the insulating substrate 2. Also good.

The liquid or paste-like insulating material is filled between the plural element parts 7 arranged in parallel by capillary action, and when the element part 7 is melted by heat generation by curing, the connection between the element parts 7 arranged in parallel is prevented. can do. For this reason, it is calculated | required that the insulating material which comprises the insulation part 8 is equipped with the heat resistance with respect to the heat_generation | fever temperature of the element part 7 by hardening.

[Control of fusing order]
The fuse element 1 is preferably provided with an insulating portion 8 between the element portions 7 of the fuse element 5. In addition, the fuse element 1 sequentially melts the plurality of element parts 7 and provides an insulating part 8 between at least the element part 7 to be blown first and the element part 7 adjacent to the element part 7 to be blown first. It is preferable.

For example, the fuse element 5 has a relatively high resistance by making the cross-sectional area of a part or all of one element part 7 smaller than the cross-sectional area of another element part among the plurality of element parts 7. As a result, when a current exceeding the rating is energized, first, a large amount of current is energized and melted from the element portion 7 having a relatively low resistance. Since the melting of the element portion 7 does not involve arc discharge due to self-heating, there is no explosive scattering of the molten metal. Thereafter, the current concentrates on the remaining high-resistance element portion 7 and finally melts with arc discharge. Thereby, the fuse element 5 can melt the element part 7 sequentially. The fuse element 5 generates an arc discharge when the element portion 7 having a small cross-sectional area is melted. However, the fuse element 5 becomes a small scale according to the volume of the element portion 7 and can prevent explosive scattering of the molten metal.

At this time, the fuse element 1 expands due to its own heat generation by providing an insulating portion 8 between the relatively low resistance element portion 7 to be melted first and the element portion adjacent to the element portion 7. It is possible to prevent the adjacent element portions 7 from contacting and aggregating. As a result, the fuse element 1 causes the element portions 7 to be blown in a predetermined fusing order, and increases the fusing time due to the integration of the adjacent element portions 7 and a decrease in insulation due to the large scale of arc discharge. Can be prevented.

Specifically, in the fuse element 1 on which the fuse element 5 composed of the three

element portions

7A, 7B, and 7C shown in FIG. 1 is mounted, the cross-sectional area of the middle element portion 7B is relatively reduced and the resistance is increased. As a result, a large amount of current is preferentially passed from the

outer element portions

7A and 7C to cause fusing, and finally the middle element portion 7B is blown. At this time, the fuse element 1 is adjacent to the

element parts

7A and 7B and adjacent to the

element parts

7B and 7C even when the

element parts

7A and 7C are melted by self-heating. While fusing in a short time without coming into contact with the element portion 7B, the element portion 7B can be fused at the end. Further, the element portion 7B having a small cross-sectional area has no contact with the

adjacent element portions

7A and 7C, and arc discharge at the time of fusing is limited to a small scale.

In addition, when the fuse element 5 is provided with three or more element portions, it is preferable that the outer element portion is blown first and the inner element portion is blown last. For example, as shown in FIG. 2, the fuse element 5 is preferably provided with three

element portions

7A, 7B, and 7C, and the middle element portion 7B is blown last.

As described above, when a current exceeding the rating is supplied to the fuse element 5, first, a large amount of current flows through the two

element portions

7A and 7C provided on the outside, and the fuse element 5 is melted by self-heating. Since the fusing of these

element portions

7A and 7C is not accompanied by arc discharge due to self-heating, there is no explosive scattering of the molten metal. Further, as described above, the

element portions

7A and 7C are melted first without contact with the adjacent element portion 7B by the insulating portion 8.

Next, the current concentrates on the element portion 7B provided on the inner side and melts while arc discharge occurs. At this time, the fuse element 5 is the outer element portion that has melted the molten metal of the element portion 7B first, even if arc discharge occurs, by finally fusing the element portion 7B provided on the inner side. It can be captured by the insulating portion 8 provided between 7A and 7C and the

element portions

7A and 7C. Therefore, scattering of the molten metal in the element portion 7B can be suppressed, and a short circuit due to the molten metal can be prevented.

Also at this time, the fuse element 5 has a cross-sectional area of a part or all of the middle element part 7B located on the inner side among the three element parts 7A to 7C, and the

other element parts

7A and 7C located on the outer side. By making it smaller than the area, the resistance may be relatively increased, and the middle element portion 7B may be blown out last. Also in this case, since the cross-sectional area is blown last by making the cross-sectional area relatively small, the arc discharge becomes small according to the volume of the element portion 7B, and the explosive scattering of the molten metal is further suppressed. be able to.

[Installation position of insulation part]
Moreover, the fuse element 1 should just provide the insulating part 8 according to the fusing part of the element part 7. FIG. As shown in FIG. 2, the fuse element 5 includes the first and second electrodes 3 by connecting each element portion 7 on the first and

second electrodes

3 and 4 provided on the insulating substrate 2. , 4 are electrically connected. In each element portion 7, current is not concentrated at both ends connected to the first and

second electrodes

3, 4, and current is concentrated at an intermediate portion between the first electrode 3 and the second electrode 4. It melts by generating heat at a high temperature.

Therefore, the fuse element 1 is provided adjacent to an intermediate portion between both end portions connected to the first electrode 3 and the second electrode 4 of each element portion 7, so that the element portion 7 adjacent to the melting element is provided. Can be prevented from touching.

[Terminal part]
When the fuse element 1 on which the fuse element 5 is mounted is mounted on a circuit board, the terminal section 10 is connected to a connection terminal formed on the circuit board. As shown in FIG. 7 is formed on both sides in the longitudinal direction. The terminal portion 10 is connected to a connection terminal formed on the circuit board via solder or the like by mounting the fuse element 1 face down on the circuit board.

The fuse element 1 is conductively connected to the circuit board via the terminal portion 10 formed in the fuse element 5, thereby reducing the resistance value of the entire element, thereby achieving downsizing and higher rating. That is, the fuse element 1 is provided with an electrode for connection to the circuit board on the back surface of the insulating substrate 2 and connected to the first and

second electrodes

3 and 4 through through holes filled with conductive paste. Due to the limitation of the hole diameter and the number of holes of through holes and castellations and the limitation of the resistivity and film thickness of the conductive paste, it is difficult to realize a resistance value lower than that of the fuse element, and it is difficult to increase the rating.

Therefore, the fuse element 1 forms the terminal portion 10 in the fuse element 5 and protrudes to the outside of the element through the cover member 6. Then, as shown in FIG. 10E, the fuse element 1 is face-down mounted on the circuit board, thereby directly connecting the terminal portion 10 to the connection terminal of the circuit board. As a result, the fuse element 1 can be prevented from being increased in resistance due to the presence of a conductive through hole, and the rating of the element is determined by the fuse element 5, so that downsizing and higher rating can be realized.

Further, in the fuse element 1, by forming the terminal portion 10 in the fuse element 5, it is not necessary to form a connection electrode with the circuit board on the back surface of the insulating substrate 2, and the first and second electrodes are formed only on the front surface 2a. It is sufficient to form the

electrodes

3 and 4, and the number of manufacturing steps can be reduced.

[Fuse element manufacturing method]
For example, as shown in FIG. 7A, the fuse element 5 formed with a plurality of element portions 7 can be manufactured by punching out two central portions of a plate-like material into a rectangular shape. The fuse element 5 is integrally supported on both sides of the three element portions 7A to 7C arranged in parallel. As shown in FIG. 7B, the fuse element 5 may be one in which one side of the three element portions 7A to 7C arranged in parallel is integrally supported.

The fuse element 5 provided with the terminal portion 10 can be manufactured, for example, by punching a plate-shaped material to form a plurality of element portions 7 and bending both side edges. Further, the fuse element 5 provided with the terminal portion 10 may connect a metal plate constituting the terminal portion 10 and the plurality of element portions 7. Or you may manufacture by connecting the metal plate which comprises the terminal part 10 on the 1st and

2nd electrodes

3 and 4. FIG.

The fuse element 1 does not have to be provided with the first and

second electrodes

3 and 4 on the insulating substrate 2 when the fuse element 5 having the terminal portion 10 and the plurality of element portions 7 is used. In this case, the insulating substrate 2 is used to dissipate heat from the fuse element 5, and a ceramic substrate having good thermal conductivity is preferably used. Further, the adhesive for connecting the fuse element 5 to the insulating substrate 2 may be non-conductive and preferably has excellent thermal conductivity.

[Multiple elements]
Further, the fuse element 1 may be manufactured by connecting a plurality of elements 11 corresponding to the element portion 7 in parallel across the first and

second electrodes

3 and 4 as fuse elements. As shown in FIG. 8, for example, three

elements

11A, 11B, and 11C are arranged in parallel. Each element 11A to 11C is formed in a rectangular plate shape, and a terminal portion 10 is bent at both ends. The element 11 has a relatively high resistance by making the cross-sectional area of the middle element 11B provided on the inner side smaller than the cross-sectional area of the

other elements

11A and 11C provided on the outer side. You may make it let.

The fuse element 5 may be connected to the connection terminal of the circuit board via the first and

second electrodes

3 and 4 without providing the terminal portion 10. In this case, the fuse element 1 has the first and

second electrodes

3 and 4 connected to an external connection terminal provided on the back surface of the insulating substrate 2 through a through hole, or the first and second electrodes 3. , 4 are connected to external connection terminals made of metal posts or the like, and the external connection terminals are connected to the connection terminals of the circuit board.

[Fuse element manufacturing process]
The fuse element 1 in which the fuse element 5 is used is manufactured by the following process. As shown in FIG. 9A, the insulating substrate 2 on which the fuse element 5 is mounted has first and

second electrodes

3 and 4 formed on the surface 2a, and between the element portions 7 of the fuse element 5. An insulating portion 8 is provided depending on the position. The fuse elements 5 are connected to the first and

second electrodes

3 and 4 by soldering or the like (FIG. 9B). Thus, the fuse element 5 is incorporated in series on the circuit formed on the circuit board by mounting the fuse element 1 on the circuit board. When the insulating portion 8 is erected on the surface 2 a of the insulating substrate 2, the insulating portion 8 of the fuse element 5 is positioned between the plurality of element portions 7 arranged in parallel.

The fuse element 5 is mounted between the first and

second electrodes

3 and 4 via a connecting material such as solder, and is soldered when the fuse element 1 is reflow-mounted on the circuit board. Further, as shown in FIG. 9C, a flux 17 is provided on the fuse element 5. By providing the flux 17, the fuse element 5 can be prevented from being oxidized and wettability can be improved, and can be blown quickly. Moreover, by providing the flux 5, the adhesion of the molten metal to the insulating substrate 2 due to arc discharge can be suppressed, and the insulation after fusing can be improved.

Next, as shown in FIG. 9 (D), the fuse element 1 is protected by mounting the cover member 6 that protects the surface 2a of the insulating substrate 2 and reduces the melting scattered matter of the fuse element 5 due to arc discharge. Complete. The cover member 6 has a pair of side walls 6a extending in the width direction at both ends in the longitudinal direction. The side walls 6a are installed on the surface 2a, and the terminal portion 10 of the fuse element 5 is directed upward from the opened side surface. It is protruding. When the insulating portion 8 is formed not on the surface 2 a of the insulating substrate 2 but on the top surface 6 b of the cover member 6, the fuse element 5 can be connected in parallel by mounting the cover member 6. An insulating portion 8 is positioned between the element portions 7.

As shown in FIG. 9 (E), the fuse element 1 is connected by face-down mounting with the surface 2a side on which the cover member 6 is provided facing the circuit board. Thereby, since each element part 7 of the fuse element 5 is covered with the cover member 6 and the terminal part 10 in the fuse element 1, the molten metal is captured by the terminal part 10 and the cover member 6 even when arc discharge occurs, Can be prevented from scattering.

[Overhang part]
Further, as shown in FIGS. 10A and 10B, the fuse element 1 has

overhang portions

3a and 4a projecting from a portion to which one element portion 7 of the first and

second electrodes

3 and 4 is connected. The distance between the electrodes formed between the projecting

portions

3a and 4a may be shorter than the distance between the electrodes at the portion to which the other element portion 7 is connected.

By mounting the element portion 7 on the

overhang portions

3a and 4a, the contact area between the element portion 7 and the first and

second electrodes

3 and 4 and the

overhang portions

3a and 4a increases. For this reason, even when the current flows and self-heats when the current flows, the element portion 7 is radiated through the first and

second electrodes

3 and 4 and the

overhang portions

3a and 4a. It becomes easier to cool than the other element portions 7 mounted on the portion where the 4a is not provided, and blows out later than the other element portions 7. Thereby, the fuse element 1 can melt the element part 7 of the fuse element 5 sequentially.

Also, by providing the

overhang portions

3a and 4a, the distance between the electrodes is shorter than that of other element portions. Since the element part 7 is easily melted as the distance between the electrodes becomes longer, the element part 7 mounted on the overhanging

parts

3a and 4a is less likely to be melted than the other element parts 7, and the other element parts 7 Fusing late. Also by this, the fuse element 1 can sequentially melt the element portion 7 of the fuse element 5.

The fuse element 1 uses a fuse element 5 provided with three or more element portions, and the overhanging portion 3a is formed at a portion of the first and

second electrodes

3 and 4 where the inner element portion 7 is mounted. 4a, and the inner element portion 7 is preferably melted last. For example, as shown in FIG. 10, a fuse element 5 having three

element portions

7A, 7B, and 7C is used, and

overhang portions

3a and 4a are provided at a portion where the middle element portion 7B is mounted. It is preferable that the portion 7B is melted at the end by facilitating cooling and shortening the distance between the electrodes.

As described above, since the fuse element 5 is accompanied by arc discharge when the last element portion 7 is melted, the element portion 7B is melted by the last element portion 7B. The molten metal of 7B can be captured by the

outer element portions

7A and 7C that have been melted first. Therefore, scattering of the molten metal in the element portion 7B can be suppressed, and a short circuit due to the molten metal can be prevented.

At this time, among the three element portions 7A to 7C, the fuse element 5 includes the

other element portions

7A and 7C located outside the partial cross-sectional area of the middle element portion 7B located inside. By making it smaller than the cross-sectional area, the resistance may be relatively increased, and the middle element portion 7B may be blown out last. Also in this case, since the cross-sectional area is finally blown by making the cross-sectional area relatively small, the arc discharge can be made small according to the volume of the element portion 7B.

[Second form]
Further, in the fuse element to which the present invention is applied, as shown in FIG. 11B, the terminal portion 10 is integrally formed with the fuse element 5, and the terminal portion 10 is fitted to the side surface of the insulating substrate 2, You may make it protrude in the back surface side of the insulated substrate 2. FIG. In the fuse element 20 described below, the same members as those of the above-described fuse element 1 are denoted by the same reference numerals, and the details thereof are omitted.

As shown in FIG. 11C, the fuse element 20 is provided with a flux 17 on the fuse element 5, and then, as shown in FIG. 11D, the cover member 6 is placed on the surface 2a of the insulating substrate 2. Manufactured by mounting. The terminal portion 10 protrudes from the open side surface of the cover member 6 to the back surface side of the insulating substrate 2. In the fuse element 20, the cover member 6 does not necessarily have to be mounted if the insulating portion 8 is provided on the surface 2 a of the insulating substrate 2 or provided by being applied and cured on the fuse element 5. .

The fuse element 20 is mounted with a connecting material such as solder with the back surface of the insulating substrate 2 facing the circuit board. Thereby, the fuse element 20 has the terminal portion 10 connected to the electrode terminal formed on the circuit board, and the fuse element 5 is connected in series with the circuit of the circuit board.

As shown in FIG. 11A, the fuse element 20 may be formed with a fitting recess 21 on the side surface of the insulating substrate 2 in which the terminal portion 10 of the fuse element 5 is fitted. By forming the fitting recess 21, the mounting area on the circuit board does not increase, and the fitting position of the fuse element 5 can be fixed.

In the fuse element 20 shown in FIG. 11, the first and

second electrodes

3 and 4 may not be formed on the surface 2 a of the insulating substrate 2. Thereby, the fuse element 20 does not need to form an electrode on the surface 2a of the insulating substrate 2, and the number of manufacturing steps can be reduced.

In the fuse element 20, the insulating substrate 2 is used to dissipate heat from the fuse element 5, and a ceramic substrate having good thermal conductivity is preferably used. Further, the adhesive for connecting the fuse element 5 to the insulating substrate 2 may be non-conductive and preferably has excellent thermal conductivity. Further, in the fuse element 20, a heat radiation electrode may be formed on the back surface of the insulating substrate 2.

Further, as shown in FIG. 12, the fuse element 20 may be manufactured by connecting a plurality of elements 11 corresponding to the element section 7 in parallel between the first and

second electrodes

3 and 4. In the fuse element 20, an insulating portion 8 is provided between the elements 11 arranged in parallel. In each element 22, the terminal portion 10 is bent and formed, and the terminal portion 10 is fitted to the side surface of the insulating substrate 2 and protrudes to the back surface side of the insulating substrate 2.

Also in this case, the first and

second electrodes

3 and 4 provided on the surface 2a of the insulating substrate 2 may not be formed. The fuse element 20 has three elements 11 arranged in parallel (11A to 11C), and the cross-sectional area of the middle element 11B provided on the inner side is larger than the cross-sectional area of the

other elements

11A and 11C provided on the outer side. It is also possible to make the resistance relatively high by making it small, and finally melt it.

[Division of the first and second electrodes]
In addition, the

fuse elements

1 and 20 include a plurality of first divided

electrodes

3 and 4 according to the mounting positions of the plurality of element portions 7 and the plurality of elements 11 of the fuse element 5. It may be divided into three and a plurality of second divided electrodes 4. For example, as shown in FIGS. 13A and 13B, the fuse element 1 includes first and

second electrodes

3 and 4 and three element portions 7A to 7C of the fuse element 5 and three elements 11A to 11A. Depending on the mounting position of 11C, it may be divided into first divided electrodes 3A to 3C and second divided electrodes 4A to 4C.

By dividing the first electrode 3 into the first divided electrodes 3A to 3C and the second electrode 4 into the second divided electrodes 4A to 4C, the fuse element 1 has the element portions 7A to 7C of the fuse element 5. Alternatively, it is possible to suppress mounting displacement or inadvertent solder accumulation due to the surface tension of the solder when the elements 11A to 11C are connected to the solder.

In the fuse element 1, the insulating portion 8 may be formed from a position adjacent to the first divided electrodes 3A to 3C to a position adjacent to the second divided electrodes 4A to 4C. As described above, the fuse element 1 is mounted on the circuit board by reflow soldering or the like, whereby the fuse element 5 is incorporated in series with the circuit formed on the circuit board. At this time, the solder for connection provided on the connection terminal of the circuit board is melted, passes through the terminal portion 10 of the fuse element 5, and on the first and

second electrodes

3, 4 provided on the surface 2 a of the insulating substrate 2. And may aggregate in the region between the element parts 7 arranged in parallel. For this reason, in the fuse element 1, the resistance value in the element portion 7 is lowered, and there is a possibility that the interruption time is delayed.

Therefore, the first and

second electrodes

3 and 4 are divided into a plurality according to the element portion 7 or the element 11, and the insulating portion 8 having no wettability with respect to solder is adjacent to the first divided electrodes 3A to 3C. By forming from the position to the position adjacent to each of the second divided electrodes 4A to 4C, the first divided electrodes 3A to 3C and the second divided electrodes are formed even if the connecting solder provided on the connection terminal of the circuit board is melted. It is possible to suppress the movement to the divided electrodes 4A to 4C, or to reduce the movement amount, and to prevent the resistance value in the element section 7 from being lowered and the interruption time from being delayed.

[Fuse element layer structure]
Next, the configuration of the fuse element 5 will be described. Note that the configuration of the fuse element 5 described below can also be applied to the element 11. The fuse element 5 described above is a low melting point metal such as solder or Pb-free solder whose main component is Sn, or a laminated body of a low melting point metal and a high melting point metal. For example, the fuse element 5 is a laminated structure including an inner layer and an outer layer, and includes a low melting point metal layer 5a as an inner layer and a refractory metal layer 5b as an outer layer laminated on the low melting point metal layer 5a (see FIG. 4). .

The low melting point metal layer 5a is preferably a metal mainly composed of Sn, and is a material generally called “Pb-free solder” (for example, M705, manufactured by Senju Metal Industry). The melting point of the low melting point metal layer 5a is not necessarily higher than the temperature of the reflow furnace, and may be melted at about 200 ° C. The high melting point metal layer 5b is a metal layer laminated on the surface of the low melting point metal layer 5a, and is, for example, Ag or Cu, or a metal mainly composed of either of them, and the fuse element 5 is removed from the reflow furnace. Therefore, it has a high melting point that does not melt even when mounting on the insulating substrate 2.

Even if the reflow temperature exceeds the melting temperature of the low melting point metal layer 5a by laminating the high melting point metal layer 5b as the outer layer on the low melting point metal layer 5a as the inner layer, the fuse element 5 5 does not lead to fusing. Therefore, the fuse element 5 can be efficiently mounted by reflow.

Also, the fuse element 5 is not melted by self-heating while a predetermined rated current flows. When a current having a value higher than the rating flows, the current is melted by self-heating, and the current path between the first and

second electrodes

3 and 4 is interrupted. At this time, the fuse element 5 uses, for example, an alloy containing 40% or more of Sn as a low melting point metal, and the melted low melting point metal layer 5a erodes the high melting point metal layer 5b, whereby the high melting point metal layer 5b melts at a temperature lower than the melting temperature. Therefore, the fuse element 5 can be blown in a short time by utilizing the erosion action of the high melting point metal layer 5b by the low melting point metal layer 5a. In addition, since the molten metal of the fuse element 5 is divided into left and right by the physical pulling action of the first and

second electrodes

3, 4, the first and second electrodes can be quickly and reliably. The current path between 3 and 4 can be interrupted.

Further, since the fuse element 5 is configured by laminating the high melting point metal layer 5b on the low melting point metal layer 5a serving as the inner layer, the fusing temperature is greatly reduced as compared with a conventional chip fuse made of a high melting point metal. be able to. Therefore, the fuse element 5 can have a larger cross-sectional area and can greatly improve the current rating as compared with a chip fuse of the same size. In addition, it can be made smaller and thinner than conventional chip fuses having the same current rating, and is excellent in quick fusing.

Also, the fuse element 5 can improve resistance to a surge (pulse resistance) in which an abnormally high voltage is instantaneously applied to the electrical system in which the fuse element 1 is incorporated. That is, the fuse element 5 must not be blown until, for example, a current of 100 A flows for several milliseconds. In this respect, since a large current flowing in a very short time flows in the surface layer of the conductor (skin effect), the fuse element 5 is provided with a refractory metal layer 5b such as Ag plating having a low resistance value as an outer layer. It is easy to flow the current applied by the surge, and it is possible to prevent fusing due to self-heating. Therefore, the fuse element 5 can greatly improve the resistance to a surge as compared with a fuse made of a conventional solder alloy.

The fuse element 5 can be manufactured by forming a high melting point metal 5b on the surface of the low melting point metal layer 5a by using a film forming technique such as an electrolytic plating method. For example, the fuse element 5 can be efficiently manufactured by performing Ag plating on the surface of the solder foil formed into a predetermined shape. In addition, the fuse element 5 is formed by coating a refractory metal on a solder foil with an electrolytic plating method or the like, and then punching a predetermined portion corresponding to a region between the element portions 7 so that the refractory metal layer is formed above and below the low melting point metal layer 5a. It has a laminated structure in which the layers 5b are laminated. Each of the elements 11 has a coating structure in which a low-melting-point metal layer 5a is an inner layer and a high-melting-point metal layer 5b is an outer layer by coating a solder foil with a high-melting point metal by an electrolytic plating method or the like.

Moreover, it is preferable that the fuse element 5 and the element 11 are formed such that the volume of the low melting point metal layer 5a is larger than the volume of the high melting point metal layer 5b. The fuse element 5 and the element 11 melt the high melting point metal by melting the low melting point metal by self-heating, and can thereby be melted and blown quickly. Accordingly, the fuse element 5 and the element 11 promote the corrosion action by forming the volume of the low melting point metal layer 5a larger than the volume of the high melting point metal layer 5b, and promptly the first and second electrodes. Between 3 and 4 can be interrupted.

Further, as described above, the fuse element 5 is formed on the fuse element 5 in order to prevent oxidation of the outer high-melting-point metal layer 5b or the low-melting-point metal layer 5a, to remove oxide during melting, and to improve solder fluidity. Flux 17 is applied to almost the entire surface of the outer layer. By applying the flux 17, the wettability of the low melting point metal (for example, solder) is enhanced, and the oxide while the low melting point metal is dissolved is removed, and the erosion action on the high melting point metal (for example, silver). Can be used to improve the fast fusing property.

Further, when the anti-oxidation film 7 such as Pb-free solder containing Sn as a main component is formed on the surface of the outermost refractory metal layer 5b by applying the flux 17, the anti-oxidation film 7 is also formed. The oxide can be removed, the refractory metal layer 5b can be effectively prevented from being oxidized, and the fast fusing property can be maintained and improved.

1 fuse element, 2 insulating substrate, 2a surface, 3rd electrode, 4nd electrode, 5 fuse element, 6 cover member, 6a side wall, 6b top surface, 7 element part, 8 insulation part, 10 terminal part, 11 elements, 17 fluxes, 20 fuse elements, 21 mating recesses

Claims

An insulating substrate;
A fuse element equipped with a plurality of parallel element parts, or a plurality of parallel fuse elements, which is mounted on the insulating substrate and melts by self-heating when current exceeding the rating is energized to cut off the energization path,
A fuse element comprising an insulating portion provided between the plurality of element portions or between the plurality of fuse elements and preventing connection between the element portions or the fuse elements arranged in parallel.
The plurality of fuse elements or the plurality of element portions are sequentially melted,
The insulating part is in parallel between the element part that blows first and the element part that is parallel to the element part that blows first, or in parallel to the fuse element that blows first and the fuse element that blows first The fuse element according to claim 1, wherein the fuse element is provided between the fuse element and the fuse element.
Having first and second electrodes provided on the insulating substrate;
The fuse element according to claim 1, wherein the element portion or the fuse element is mounted across the first and second electrodes.
4. The fuse element according to claim 3, wherein the insulating portion is provided in a region between the first electrode and the second electrode.
4. The fuse element according to claim 3, wherein the fuse element is solder-connected to the first and second electrodes.
The fuse element is
A low melting point metal layer;
A high melting point metal layer laminated on the low melting point metal layer,
3. The fuse element according to claim 1, wherein the low melting point metal layer uses an action of eroding and cutting the high melting point metal layer during the energization.
The fuse element according to claim 6, wherein the refractory metal layer is laminated above and below the low melting point metal.
The fuse element according to claim 6, wherein the fuse element has a covering structure in which the low melting point metal is an inner layer and the high melting point metal layer is an outer layer.
The fuse element according to claim 6, wherein the fuse element has a volume of the low melting point metal layer larger than a volume of the high melting point metal layer.
The fuse element according to claim 1 or 2, wherein a blocking part of the fuse element on the insulating substrate is covered by a cover member.
The fuse element according to claim 10, wherein the insulating member is provided on the cover member.
The fuse element according to claim 1 or 2, wherein the insulating portion is provided on a surface of the insulating substrate.
3. The fuse element according to claim 1, wherein the insulating part is formed by curing an insulating material applied between the plurality of element parts or between the plurality of fuse elements.
A plurality of element parts arranged in parallel;
An insulating portion that is provided between the plurality of element portions and prevents connection between the element portions arranged in parallel;
A fuse element in which the above-mentioned plurality of element parts are fused by self-heating due to energization of a current exceeding the rating.