WO2016117578A1

WO2016117578A1 - Fuse element and circuit module

Info

Publication number: WO2016117578A1
Application number: PCT/JP2016/051482
Authority: WO
Inventors: 裕治古内; 幸市向
Original assignee: デクセリアルズ株式会社
Priority date: 2015-01-20
Filing date: 2016-01-19
Publication date: 2016-07-28
Also published as: TW201633352A; JP2016134317A

Abstract

This fuse element is provided with an opening for releasing internal pressure, and maintains both the strength of adhesion with an insulating substrate and the insulation property after an electric current path is blocked. The fuse element is provided with: an insulating substrate 10; a plurality of electrodes 11, 12 formed on a surface 10a of the insulating substrate 10; a soluble conductor 13 that is connected to the area between the electrodes 11, 12, and that, by blowing out, blocks the area between the electrodes 11, 12; and a case 20 that has a side surface 21, which is adhered on the surface 10a of the insulating substrate 10 to which the soluble conductor 13 is provided, and a top surface 22 covering the surface 10a of the insulating substrate 10. The case 20 is provided with an opening 23 that penetrates into the case 20 at a position other than the lower part of the side surface 21 that is connected to the surface 10a of the insulating substrate 10.

Description

Fuse element and circuit module

The present invention relates to a fuse element that protects a circuit by cutting off a power supply line and a signal line, and a circuit module on which the fuse element is mounted.
This application claims priority on the basis of Japanese Patent Application No. 2015-008931 filed on January 20, 2015 in Japan. This application is incorporated herein by reference. Incorporated.

Conventionally, for example, as a fuse element of a protection circuit for a lithium ion secondary battery, a fusible conductor is connected between a first electrode, a heating element extraction electrode, and a second electrode formed on an insulating substrate, thereby providing a current path. The circuit side intends to make the fusible conductor on this current path blown by self-heating due to overcurrent, or by energizing a heating element provided inside the fuse element by an external signal. There are some which melt the soluble conductor. In this fuse element, the melted liquid soluble conductor is collected on the conductor layer connected to the heating element, whereby the first and second electrodes are separated to interrupt the current path.

Such a fuse element is generally covered with a case adhered to the surface of the insulating substrate while a soluble conductor is mounted on the insulating substrate on which the first and second electrodes and the heating element extraction electrode are formed. As a result, the inside is protected and the handleability is improved.

Japanese Patent No. 2790433

Here, when such a fuse element is instantaneously heated when an overcurrent or the like is interrupted and the air inside the case expands rapidly, an opening for releasing the pressure inside the element is provided or sealed. It is necessary to make the housing strong enough to withstand the expansion.

However, in order to increase the strength of the casing, it is necessary to form a cylindrical or box-like structure with ceramic or the like, and there is a problem that the cost increases. A method of increasing the strength by a method such as injection molding is also conceivable, but when the soluble conductor inside melts, the first and second electrodes are separated by agglomerating on the conductor layer after expanding into a spherical shape. Therefore, it is necessary to secure a space in which the soluble conductor melts and flows, and it cannot be applied.

Also, as shown in FIG. 16, in the case where the opening 102 is provided in the case 101, a method of providing a depression on the bonding surface with the insulating substrate 100 has been performed because of easy plastic molding. However, in this method, as the fuse element is further downsized, the adhesion area is reduced, so that the adhesion strength is lowered, and the thermal energy due to melting at the time of interruption is easily concentrated. There was a problem that the case fell off due to inability to withstand the expansion of internal air.

Furthermore, when the opening is not in an appropriate position, the vaporized material when the fuse element is blown by overcurrent cannot be efficiently released, and sputtering is performed between the first and second electrodes that should be insulated originally. There was also a problem that the phenomenon occurred and appropriate insulation could not be secured.

Therefore, the present invention has a fuse element that has an opening for releasing the pressure inside the element, has an adhesive strength with an insulating substrate, prevents the case from falling off, and can ensure insulation after interruption of the current path, and An object is to provide a circuit module using the same.

In order to solve the above-described problem, a fuse element according to the present invention includes an insulating substrate, a plurality of electrodes formed on a surface of the insulating substrate, and the plurality of electrodes connected between the plurality of electrodes and fused. A case having a fusible conductor that cuts off the electrodes, a side surface that is bonded onto the surface of the insulating substrate on which the fusible conductor is provided, and a top surface that covers the surface of the insulating substrate. The case is provided with an opening penetrating inside the case at a position excluding a lower portion in contact with the surface of the insulating substrate.

The circuit module according to the present invention includes a fuse element and a circuit board on which the fuse element is surface-mounted, and the fuse element includes an insulating substrate and a plurality of electrodes formed on the surface of the insulating substrate. A soluble conductor that is connected between the plurality of electrodes and is cut off between the plurality of electrodes by fusing, a side surface that is connected on the surface of the insulating substrate provided with the soluble conductor, and And a case having a top surface covering the surface of the insulating substrate, wherein the case is provided with an opening penetrating inside the case at a position excluding a lower portion in contact with the surface of the insulating substrate. .

According to the present invention, by providing an opening that penetrates the inside of the case at a position excluding the lower portion that contacts the surface of the insulating substrate on the side of the case, the expansion gas generated at the time of melting the soluble conductor is discharged, and the case Peeling and damage from the insulating substrate can be prevented.

In addition, according to the present invention, no depression is formed on the lower surface of the case side surface bonded to the surface of the insulating substrate, the bonding area can be ensured to the maximum, and even when downsizing is advanced, The case is not peeled off from the surface of the insulating substrate.

Furthermore, according to the present invention, it is possible to efficiently exhaust the vaporized material when the fuse element is blown by overcurrent toward the upper side of the insulating substrate, and the vaporized material is formed on the surface of the insulating substrate. It is also possible to prevent a situation in which the insulating property is impaired due to adhesion between the second electrodes.

FIG. 1A is a plan view showing a fuse element to which the present invention is applied without a case, and FIG. 1B is a cross-sectional view of a circuit module to which the present invention is applied. FIG. 2 is an external perspective view showing the back surface of the fuse element to which the present invention is applied. FIG. 3 is an external perspective view showing a fuse element having an opening on the top surface of the case. FIG. 4 is a plan view showing a fuse element having an opening on the center line in the width direction and the longitudinal direction of the insulating substrate on the top surface. FIG. 5 is an external perspective view showing a fuse element provided with an opening extending over the top and side surfaces of the case. FIG. 6 is a plan view showing a fuse element having openings at corners of the top surface. FIG. 7 is an external perspective view showing a fuse element provided with openings extending over the top corner and side corners of the case. FIG. 8 is a plan view showing a fuse element in which an opening is provided on the top surface above the melted portion of the fusible conductor. FIG. 9 is a plan view showing a state where the fusible conductor is blown into a linear shape. FIG. 10 is a plan view showing a fuse element in which an opening is provided above the end portion of the linear fused portion of the soluble conductor on the top surface. FIG. 11 is a plan view showing a fuse element in which an opening is provided in a side edge portion of the top surface on an extension line of a linear fusing portion of a fusible conductor. FIG. 12 is an external perspective view showing a fuse element provided with an opening on the center line in the width direction and the longitudinal direction of the insulating substrate on the side surface. FIG. 13 is an external perspective view showing a fuse element in which an opening is provided at a corner of a side surface. FIG. 14 is a diagram illustrating a corridor configuration of a battery pack to which a fuse element and a circuit module are applied. FIG. 15 is a diagram illustrating a circuit configuration of the fuse element. FIG. 16 is an external perspective view showing a fuse element according to a reference example.

Hereinafter, a fuse element and a circuit module 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.

The circuit module 3 to which the present invention is applied is one in which a fuse element 1 is surface-mounted on a circuit board 2. For example, a protection circuit for a lithium ion secondary battery is formed on the circuit board 2, and the fuse element 1 is surface-mounted, whereby the soluble conductor 13 is incorporated on the charge / discharge path of the lithium ion secondary battery. When a large current exceeding the rating of the fuse element 1 flows, the circuit module 3 blocks the current path by fusing the fusible conductor 13 by self-heating (Joule heat). In addition, the circuit module 3 cuts off the current path by energizing the heating element 14 at a predetermined timing by a current control element provided on the circuit board 2 or the like, and fusing the soluble conductor 13 by the heat generation of the heating element 14. be able to. 1A is a plan view showing the fuse element 1 to which the present invention is applied without a case, and FIG. 1B is a cross-sectional view of a circuit module 3 to which the present invention is applied. It is.

[Fuse element]
As shown in FIG. 1A, the fuse element 1 includes an insulating substrate 10, a heating element 14 stacked on the insulating substrate 10 and covered with an insulating member 15, and first elements formed at both ends of the insulating substrate 10. The electrode 11 and the second electrode 12, the heating element extraction electrode 16 laminated on the insulating member 15 so as to overlap the heating element 14, and both ends thereof are connected to the first and

second electrodes

11 and 12, respectively. And a soluble conductor 13 whose central portion is connected to the heating element extraction electrode 16.

The insulating substrate 10 is formed in a substantially square shape by an insulating member such as alumina, glass ceramics, mullite, zirconia. In addition, the insulating substrate 10 may be made of a material used for a printed wiring board such as a glass epoxy board or a phenol board, but it is necessary to pay attention to the temperature at which the fusible conductor 13 is melted.

[First and second electrodes]
The first and

second electrodes

11 and 12 are opened by being spaced apart from each other in the vicinity of opposite side edges on the surface 10a of the insulating substrate 10, and a soluble conductor 13 to be described later is mounted. Thus, they are electrically connected via the soluble conductor 13. Further, the first and

second electrodes

11 and 12 generate a large current exceeding the rating through the fuse element 1 and the fusible conductor 13 is melted by self-heating (Joule heat), or the heating element 14 generates heat when energized. The fusible conductor 13 is cut off by fusing.

As shown in FIG. 2, the first and

second electrodes

11 and 12 are provided on the back surface 10f through castellations provided on the first and second side surfaces 10b and 10c of the insulating substrate 10, respectively. The

external connection electrodes

11a and 12a are connected. The fuse element 1 is connected to the circuit board 2 on which an external circuit is formed via these

external connection electrodes

11a and 12a, and constitutes a part of the energization path of the external circuit.

The first and

second electrodes

11 and 12 can be formed using a general electrode material such as Cu or Ag. In addition, a coating such as Ni / Au plating, Ni / Pd plating, or Ni / Pd / Au plating is coated on the surfaces of the first and

second electrodes

11 and 12 by a known method such as plating. Preferably it is. As a result, the fuse element 1 can prevent the first and

second electrodes

11 and 12 from being oxidized, and can prevent a change in rating due to an increase in conduction resistance. Further, when the fuse element 1 is reflow-mounted, the first and

second electrodes

11 and 12 are obtained by melting the connecting solder for connecting the fusible conductor 13 or the low melting point metal forming the outer layer of the fusible conductor 13. Can be prevented from being eroded.

[Heating element]
The heating element 14 is a conductive member that generates heat when energized, and is made of, for example, W, Mo, Ru, Cu, Ag, or an alloy containing these as main components. The heating element 14 is obtained by mixing a powdered material of these alloys, compositions, or compounds with a resin binder or the like, forming a paste on the insulating substrate 10 using a screen printing technique, and firing it. Etc. can be formed. The heating element 14 has one end connected to the first heating element electrode 18 and the other end connected to the second heating element electrode 19.

In the fuse element 1, an insulating member 15 is disposed so as to cover the heating element 14, and a heating element extraction electrode 16 is formed so as to face the heating element 14 through the insulating member 15. In order to efficiently transfer the heat of the heating element 14 to the soluble conductor 13, an insulating member 15 may be laminated between the heating element 14 and the insulating substrate 10. As the insulating member 15, for example, glass can be used.

One end of the heating element extraction electrode 16 is connected to the first heating element electrode 18 and is connected to one end of the heating element 14 via the first heating element electrode 18. The first heating element electrode 18 is formed on the third side surface 10 d side of the insulating substrate 10, and the second heating element electrode 19 is formed on the fourth side surface 10 e side of the insulating substrate 10. The second heating element electrode 19 is connected to an external connection electrode 19a formed on the back surface 10f of the insulating substrate 10 through a castellation formed on the fourth side surface 10e.

The heating element 14 is connected to an external circuit formed on the circuit board 2 via the external connection electrode 19a by mounting the fuse element 1 on the circuit board 2. The heating element 14 can be connected to the first and

second electrodes

11 and 12 by being energized through the external connection electrode 19a at a predetermined timing to cut off the energization path of the external circuit and generating heat. The molten conductor 13 can be blown. Moreover, since the heat generating body 14 also cut | disconnects its energization path | route when the soluble conductor 13 blows, heat_generation | fever stops.

[Soluble conductor]
The fusible conductor 13 is made of a material that is quickly melted by the heat generated by the heating element 14, and for example, a low melting point metal such as solder or Pb-free solder whose main component is Sn can be suitably used.

Further, the fusible conductor 13 may be made of a high melting point metal such as In, Pb, Ag, Cu, or an alloy mainly containing any of these, or a laminate of a low melting point metal and a high melting point metal. It may be a body. By including the high melting point metal and the low melting point metal, even when the reflow temperature exceeds the melting point of the low melting point metal when the fuse element 1 is reflow mounted, Outflow to the outside can be suppressed and the shape of the soluble conductor 13 can be maintained. In addition, even when fusing, the low melting point metal melts, and the high melting point metal is eroded (soldered), so that the fusing can be quickly performed at a temperature lower than the melting point of the high melting point metal.

The soluble conductor 13 is connected to the heating element extraction electrode 16 and the first and

second electrodes

11 and 12 by soldering or the like. The fusible conductor 13 can be easily connected by reflow soldering.

The soluble conductor 13 is preferably coated with a flux 18 for the purpose of preventing oxidation and improving wettability.

[Case]
The fuse element 1 is provided with a case 20 on the surface 10a of the insulating substrate 10 in order to protect the inside. The case 20 is formed in a substantially rectangular shape according to the shape of the insulating substrate 10. As shown in FIG. 1B, the case 20 includes a side surface 21 connected to the surface 10a of the insulating substrate 10 provided with the soluble conductor 13, and a top surface that covers the surface 10a of the insulating substrate 10. 22, the fusible conductor 13 expands spherically on the surface 10 a of the insulating substrate 10 when melted, and the molten conductor aggregates on the heating element extraction electrode 16 and the first and

second electrodes

11, 12. Enough internal space.

Further, as shown in FIGS. 3 to 13, the case 20 is provided with an opening 23 penetrating into the case 20 at a position excluding the lower portion of the side surface 21 in contact with the surface 10a of the insulating substrate 10. By providing the opening 23, the fuse element 1 can discharge the expanding gas generated when the fusible conductor 13 is melted, and can prevent the case from being peeled off or damaged.

Further, the fuse element 1 is provided with an opening 23 that does not reach the adhesive surface with the surface 10a of the insulating substrate 10 at a position other than the lower portion of the side surface 21, so that the side surface 21 adhered to the surface 10a of the insulating substrate 10 is provided. No depression is formed on the lower surface, and the bonding area can be ensured to the maximum. Therefore, the fuse element 1 can prevent a decrease in the adhesive strength due to a decrease in the bonding area of the case 20 to the insulating substrate 10, and the case 20 is peeled off from the surface 10 a of the insulating substrate 10 even when miniaturization progresses. I don't have to.

Further, the fuse element 1 can efficiently exhaust the vaporized material when the fuse element is blown by an overcurrent toward the upper side of the insulating substrate 10 by providing the opening 23 at a position excluding the lower portion of the side surface 21. it can. Therefore, the fuse element 1 can also prevent a situation in which the vaporized substance adheres between the first and

second electrodes

11 and 12 formed on the surface 10a of the insulating substrate 10 and inhibits insulation.

It should be noted that the shape of the opening 23 may be any shape such as a circle or a rectangle. Also, the size of the opening can be arbitrarily set, and when the circular opening 23 is formed, for example, the diameter can be 0.05 mm or more. Further, when the opening 23 is a square, for example, one side can be a size of 0.05 mm or more, and when the opening 23 is a rectangle, a short side can be a size of 0.05 mm or more, for example. .

[On center line / side edge]
Here, as shown in FIGS. 3 and 4, the case 20 is provided with one or more openings 23 on the top surface 22, and the center line L _{1 in} the width direction of the insulating substrate 10 and / or the longitudinal direction. it is preferably provided on the center line L ₂ of. As shown in FIG. 1 (A), the fusible conductor 13 is disposed at a substantially central portion of the insulating substrate 10, so that the vaporized substance or the case 20 can be used when self-heating due to overcurrent or fusing due to heat generation of the heating element 14. When the internal air rapidly expands, the opening 23 is formed on the center line L ₁ L _{2 in} the width direction and / or the longitudinal direction of the insulating substrate 10 on the top surface 22, so that the vaporized substance or the expanded air is formed. It becomes easy to miss.

At this time, the opening 23 is preferably formed in the side edge 22 a of the top surface 22. Since the fusible conductor 13 is disposed at a substantially central portion of the insulating substrate, the opening 23 is formed in the side edge 22a of the top surface 22 so that the path of the blast of the vaporized substance or the expanded air can be improved. Opened and can be exhausted efficiently. Further, the side edge portion 22a of the top surface 22 constitutes a corner portion by adjoining the upper side of the side surface 21 of the case 20, and is also a portion where vaporized substances and blasts of expanded air tend to concentrate. By providing 23, it is possible to make the blast easier to escape.

Further, by forming the opening 23 in the side edge portion 22a of the top surface 22, the handling of the fuse element 1 in the mounting machine is handled as compared with the case where the opening 23 is formed in the center of the top surface 22. There is no problem with sex.

Note that at least one opening 23 is provided on the center line L ₁ L _{2 in} the width direction and / or the longitudinal direction of the insulating substrate 10 on the top surface 22, and is preferably provided evenly on the top surface 22. For example, the openings 23 are preferably provided evenly at the four side edge portions 22 a on the center line L _{1 in} the width direction and the center line L _{2 in the} longitudinal direction of the insulating substrate 10 on the top surface 22. The opening 23 may be provided equally in two places opposite side edge portions 22a on the center line L ₂ of the center line L ₁ or on longitudinal width direction of the insulating substrate 10 of the top surface 22.

Further, the opening 23 may be formed from the side edge portion 22a of the top surface 22 to the upper portion of the side surface 21 as shown in FIG. By opening from the top surface 22 to the side surface 21, the blast is efficiently exhausted from the corner portion where the side edge portion 22a of the top surface 22 and the upper side of the side surface 21 are adjacent to each other, where vaporized substances and blasts of expanded air tend to concentrate. be able to.

[Corner of top surface]
In addition, the case 20 may be provided with an opening 23 at a corner 22b of the top surface 22 as shown in FIG. At this time, the openings 23 are preferably provided at one or more corners 22b of the top surface 22 and provided at all four corners. Since the corner portion 22b of the top surface 22 tends to concentrate the vaporized substance and the blast of the expanded air, providing the opening 23 in the corner portion 22b makes it easier to escape the blast.

In addition, as shown in FIG. 7, you may form the opening part 23 from the corner | angular part 22b of the top | upper surface 22 to the corner | angular part by the side of the top | upper surface 22 of the two side surfaces 21 adjacent to the said corner | angular part 22b. Thereby, a blast can be efficiently exhausted from the corner | angular part which the side edge part 22a of the top | upper surface 22 and the upper side of the side surface 21 adjoin easily where the blast of a vaporization substance and the expanded air tends to concentrate.

Further, the case 20 has the opening 23 formed in the side edge 22a on the center line L ₁ L _{2 in} the width direction and / or the longitudinal direction of the insulating substrate 10 of the top surface 22 and also in the corner 22b. May be.

[Upper fusing part]
In addition, as shown in FIG. 1A, the case 20 has an opening 23 formed on the fusible conductor 13 as shown in FIG. You may form above the fusing part 13a. By providing the opening 23 above the fusing part 13a of the top surface 22, the blast of the vaporized substance and the expanded air can be efficiently exhausted.

In addition, since the fusing portion 13a of the fusible conductor 13 is off the center of the top surface 22, the fuse element 1 can be handled by a mounting machine as compared with the case where the opening 23 is provided at the center of the top surface 22. There is no problem in handling.

[Upper end of linear fusing part]
In addition, as shown in FIG. 9, the case 20 is formed on the soluble conductor 13 on the top surface 22 as shown in FIG. You may form above the edge part of the linear fusing part 13b. The fusible conductor 13 has an end portion of the linear fusing portion 13b on the top surface 22 because the end portion of the fusing portion 13b tends to be a final fusing portion when the fusing portion is linearly long. By providing the opening 23 on the upper side, the vaporized substance at the time of fusing and the blast of the expanded air can be efficiently exhausted.

Further, the upper end of the linear fusing part 13b of the top surface 22 is out of the center of the top surface 22, so that the fuse element 1 of the fuse element 1 is compared with the case where the opening 23 is provided in the center of the top surface 22. There is no problem in handling such as handling on the mounting machine.

[On the extended line of the linear fusing part]
Moreover, as shown in FIG. 11, the case 20 is above the extension line of the linear melted part 13b formed by the fusible conductor 13 being melted in a linear shape, and is on the side edge 22a of the top surface 22. You may form in. Also in this case, when the fusible conductor 13 is blown by self-heating cutoff or the like, the final fusing point is likely to be the end of the linear fusing part 13b, and therefore above the extension line of the linear fusing part 13b, By forming the opening 23 in the side edge 22a of the top surface 22, it is possible to efficiently exhaust the vaporized material at the time of fusing and the blast of the expanded air.

In this case as well, the opening 23 may be formed from the side edge 22 a of the top surface 22 to the top of the side surface 21. By opening from the top surface 22 to the side surface 21, the blast is efficiently exhausted from the corner portion where the side edge portion 22a of the top surface 22 and the upper side of the side surface 21 are adjacent to each other, where vaporized substances and blasts of expanded air tend to concentrate. be able to.

[side]
Further, the case 20 may be provided with one or a plurality of openings 23 on the side surface 21. As described above, the opening 23 formed in the side surface 21 is also provided at a position excluding the lower portion of the side surface 21 in contact with the surface 10a of the insulating substrate 10.

At this time, as shown in FIG. 12, the opening 23 formed in the side surface 21 is provided on the center line L _{1 in} the width direction and / or the center line L _{2 in the} longitudinal direction of the insulating substrate 10. Is preferred. As described above, since the fusible conductor 13 is disposed at a substantially central portion of the insulating substrate, when the vaporized substance or the air inside the case 20 rapidly expands at the time of fusing, the insulating substrate 10 on the side surface 21 is expanded. By forming the opening 23 on the center line L _{1 in the} width direction and / or on the center line L _{2 in the} longitudinal direction, the vaporized substance and the expanded air can be easily released.

Note that at least one opening 23 is provided on the center line L ₁ L _{2 in} the width direction and / or the longitudinal direction of the insulating substrate 10 on the side surface 21, and is preferably provided evenly on the plurality of side surfaces 21. For example, the openings 23 are preferably provided evenly on the four side surfaces 21 on the center line L _{1 in} the width direction and the center line L _{2 in the} longitudinal direction of the insulating substrate 10. The openings 23 may be equally provided on the two opposite side surfaces 21 on the center line L _{1 in} the width direction or the center line L _{2 in the} longitudinal direction of the insulating substrate 10.

Alternatively, the opening 23 formed in the side surface 21 may be formed in a corner portion 21a on the top surface 22 side of the side surface 21, as shown in FIG. Since the corner portion 21a of the side surface 21 tends to concentrate the vaporized substance and the blast of the expanded air, the blast can be more easily released by providing the opening portion 23 in the corner portion 21a.

In addition, you may form the opening part 23 over the corner | angular part 21a of the side surface 21 adjacent to each other. Further, as described above, the opening 23 may be formed from the corner 22b of the top surface 22 to the corner 21a on the top surface 22 side of one or two side surfaces 21 adjacent to the corner 22b. . Also by these, the corner 21a of the side surface 21 where the vaporized substance and the blast of the expanded air are likely to concentrate, and the corner 22b of the top surface 22 and the corner 21a of the side surface 21 on the top surface 22 side are adjacent to each other. The blast can be exhausted well.

In the fuse element 1 described above, a configuration in which the heating element 14 is provided and the soluble conductor 13 is blown by the heat generation of the heating element 14 in addition to the self-heating cutoff of the soluble conductor 13 due to a large current exceeding the rating has been described. However, the fuse element 1 to which the present invention is applied may be one in which the current path is interrupted by the self-heating cutoff of the fusible conductor 13 due to a large current exceeding the rating without including the heating element 14.

[Circuit board]
Next, the circuit board 2 on which the fuse element 1 is mounted will be described. As the circuit board 2, for example, a known insulating substrate such as a rigid substrate such as a glass epoxy substrate, a glass substrate, or a ceramic substrate, or a flexible substrate is used. Further, as shown in FIG. 1B, the circuit board 2 has a mounting portion on which the fuse element 1 is surface-mounted by reflow or the like, and is provided on the back surface 10a of the insulating substrate 10 of the fuse element 1 in the mounting portion. Connection electrodes connected to the

external connection terminals

11a, 12a, and 19a are provided. The circuit board 2 is mounted with an element such as an FET for energizing the heating element 14 of the fuse element 1.

[Usage of circuit module]
Next, a method of using the fuse element 1 and the circuit module 3 in which the fuse element 1 is surface-mounted on the circuit board 2 will be described. As shown in FIG. 14, the circuit module 3 is used, for example, as a circuit in a battery pack of a lithium ion secondary battery.

For example, the fuse element 1 is used by being incorporated in a battery pack 40 having a battery stack 45 including battery cells 41 to 44 of a total of four lithium ion secondary batteries.

The battery pack 40 includes a battery stack 45, a charge / discharge control circuit 50 that controls charging / discharging of the battery stack 45, a fuse element 1 to which the present invention that cuts off charging when the battery stack 45 is abnormal, and each battery cell A detection circuit 46 for detecting the voltages 41 to 44 and a current control element 47 for controlling the operation of the fuse element 1 according to the detection result of the detection circuit 46 are provided.

The battery stack 45 is formed by connecting battery cells 41 to 44 that need to be controlled for protection from overcharge and overdischarge states, and is detachable through the positive terminal 40a and the negative terminal 40b of the battery pack 40. Are connected to the charging device 55, and the charging voltage from the charging device 55 is applied. The electronic device can be operated by connecting the positive terminal 40a and the negative terminal 40b of the battery pack 40 charged by the charging device 55 to the electronic device operated by the battery.

The charge / discharge control circuit 50 includes two

current control elements

51 and 52 connected in series to a current path flowing from the battery stack 45 to the charging device 55, and a control unit 53 that controls operations of these

current control elements

51 and 52. Is provided. The

current control elements

51 and 52 are configured by, for example, field effect transistors (hereinafter referred to as FETs), and control the gate voltage by the control unit 53 to control conduction and interruption of the current path of the battery stack 45. . The control unit 53 operates by receiving power supply from the charging device 55, and controls the current so that the current path is interrupted when the battery stack 45 is overdischarged or overcharged according to the detection result by the detection circuit 46. The operation of the

elements

51 and 52 is controlled.

The fuse element 1 is connected to, for example, a charge / discharge current path between the battery stack 45 and the charge / discharge control circuit 50, and its operation is controlled by the current control element 47.

The detection circuit 46 is connected to the battery cells 41 to 44, detects the voltage values of the battery cells 41 to 44, and supplies the voltage values to the control unit 53 of the charge / discharge control circuit 50. The detection circuit 46 outputs a control signal for controlling the current control element 47 when any one of the battery cells 41 to 44 becomes an overcharge voltage or an overdischarge voltage.

The current control element 47 is constituted by, for example, an FET, and when the voltage value of the battery cells 41 to 44 exceeds a predetermined overdischarge or overcharge state by the detection signal output from the detection circuit 46, the fuse element 1 is operated to control the charge / discharge current path of the battery stack 45 to be cut off regardless of the switch operation of the

current control elements

51 and 52.

In the battery pack 40 having the above configuration, the configuration of the fuse element 1 will be specifically described.

First, the fuse element 1 to which the present invention is applied has a circuit configuration as shown in FIG. That is, the fuse element 1 generates heat that melts the soluble conductor 13 by energizing the soluble conductor 13 connected in series via the heating element extraction electrode 16 and the connection point of the soluble conductor 13 to generate heat. This is a circuit configuration comprising the body 14. In the fuse element 1, for example, the fusible conductor 13 is connected in series on the charge / discharge current path, and the heating element 14 is connected to the current control element 47. The first electrode 11 of the fuse element 1 is connected to the open end of the battery stack 45 via the external connection electrode 11a, and the second electrode 12 is connected to the positive terminal 40a side of the battery pack 40 via the external connection electrode 12a. Connected to the open end. Further, the heating element 14 is connected to the charge / discharge current path of the battery pack 40 by being connected to the soluble conductor 15 via the heating element extraction electrode 13, and via the heating element electrode 16 and the external connection electrode 19 a. It is connected to the current control element 47.

In such a battery pack 40, when the heating element 14 of the fuse element 1 is energized and generates heat, the fusible conductor 13 melts and is attracted onto the heating element extraction electrode 16 due to its wettability. As a result, the fuse element 1 can reliably cut off the current path when the fusible conductor 13 is melted. In addition, since the fusible conductor 15 is cut off, the power supply path to the heating element 14 is also cut off, so that the heating of the heating element 14 is also stopped.

In addition, when an unexpected large current exceeding the rating of the fuse element 1 flows on the charge / discharge path, the battery pack 40 cuts off the current path by fusing the fusible conductor 13 by self-heating (Joule heat). can do.

At this time, since the fuse element 1 is provided with an opening 23 penetrating the inside of the case 20 at a position excluding the lower portion of the side surface 21 in contact with the surface 10a of the insulating substrate 10 of the case 20, the fusible conductor 13 is fused. It is possible to discharge the vaporized substance of the fusible conductor 13 and the air inside the expanded case 20 that are sometimes generated, and to prevent the case from being peeled off or damaged from the insulating substrate 10.

Further, the fuse element 1 is provided with the opening 23 at a position excluding the lower portion of the side surface 21, so that no depression is formed on the lower surface of the side surface 21 bonded to the surface 10a of the insulating substrate 10, and the bonding area is maximized. Can be secured to the limit. Therefore, the fuse element 1 can prevent a decrease in the adhesive strength due to a decrease in the bonding area of the case 20 to the insulating substrate 10, and the case 20 is peeled off from the surface 10 a of the insulating substrate 10 even when miniaturization progresses. There is no need to do.

second electrodes

Note that the fuse element 1 to which the present invention is applied is not limited to use in a battery pack of a lithium ion secondary battery, and can of course be applied to various uses that require interruption of a current path by an electric signal.

1 fuse element, 2 circuit board, 3 circuit module, 10 insulating board, 10a surface, 10b first side, 10c second side, 10d third side, 10e fourth side, 10f back side, 11 first Electrode, 11a external connection electrode, 12 second electrode, 12a external connection electrode, 13 fusible conductor, 13a fusing part, 13b linear fusing part, 14 heating element, 15 insulating member, 16 heating element extraction electrode, 18 first Heating element electrode, 19 second heating element electrode, 19a external connection electrode, 20 case, 21 side surface, 21a corner portion, 22 top surface, 22a side edge portion, 22b corner portion, 23 opening portion, 40 battery pack, 41 44 battery cells, 45 battery stacks, 46 detection circuits, 47 current control elements, 50 charge / discharge control circuits, 51, 2 current control element, 53 control unit, 55 charging device

Claims

An insulating substrate;
A plurality of electrodes formed on the surface of the insulating substrate;
A soluble conductor that is connected between the plurality of electrodes and cuts between the plurality of electrodes by fusing; and
A case having a side surface adhered on the surface of the insulating substrate provided with the soluble conductor and a top surface covering the surface of the insulating substrate;
The fuse element, wherein the case is provided with an opening penetrating inside the case at a position excluding a lower portion in contact with the surface of the insulating substrate.
2. The fuse element according to claim 1, wherein the case is provided with one or a plurality of the opening portions on the top surface and on a center line in a width direction and / or a longitudinal direction of the insulating substrate.
3. The fuse element according to claim 2, wherein the opening is formed at a side edge of the top surface.
The fuse element according to any one of claims 1 to 3, wherein the case has the opening provided at a corner of the top surface.
3. The fuse element according to claim 1, wherein the opening is formed above a fusing part of the soluble conductor.
The fusible conductor is blown linearly across the width or longitudinal direction,
The fuse element according to claim 5, wherein the opening is formed above an end of a fusing line where the soluble conductor on the top surface is fused.
The fusible conductor is blown linearly across the width or longitudinal direction,
The fuse element according to claim 5, wherein the opening is formed above an extension line of a fusing line where the fusible conductor is fused, and is formed at a side edge of the top surface.
The fuse element according to any one of claims 1 to 3, wherein the opening is opened from the top surface to the side surface.
2. The fuse element according to claim 1, wherein the case is provided with one or a plurality of the opening portions on the side surface and on a center line in a width direction and / or a longitudinal direction of the insulating substrate.
10. The fuse element according to claim 1, wherein the case is provided at a corner where the opening is in contact with the top surface of the side surface.
4. The fuse element according to claim 1, wherein the opening is a circle having a diameter of 0.05 mm or more or a square having a side of 0.05 mm or more.
A fuse element;
A circuit board on which the fuse element is surface-mounted,
The fuse element is
An insulating substrate;
A plurality of electrodes formed on the surface of the insulating substrate;
A soluble conductor that is connected between the plurality of electrodes and cuts between the plurality of electrodes by fusing; and
A case having a side surface connected on the surface of the insulating substrate provided with the soluble conductor, and a top surface covering the surface of the insulating substrate;
The circuit module is a circuit module in which an opening that penetrates the case is provided at a position excluding a lower portion that contacts the surface of the insulating substrate.