Protective device and manufacturing method thereof

Abstract

The present disclosure enables rapid and reliable fusing even if the cross-sectional area of a fuse element is increased by appropriately coating a flux. The present invention is provided with: an insulating substrate (2); a heating element (4); an insulating layer (5) covering the heating element (4); an intermediate electrode (6); a fuse element (3); a cover member (30); and a flux (7) in which a protrusion (31) is provided on the lid member (30) so as to face the intermediate electrode (6), the intermediate electrode (6) having a length greater than the width of the fuse element (3) in a direction orthogonal to the energization direction of the fuse element (3), at least one of the ends (6a, 6b) of the intermediate electrode (6) protruding from the fuse element (3), and the other end of the intermediate electrode (6) protruding from the fuse element (3). The protrusion (31) is provided at a position facing the position of the intermediate electrode (6) on which the fuse element (3) is mounted, and at a position facing the ends (6a, 6b) of the intermediate electrode (6) on which the fuse element (3) is not mounted.

Description

Technical Field

[0001] The present technology relates to a protective device installed on a current path, which cuts off the current path by melting a fuse element through heating by a heating element. This application is an application claiming priority based on Japanese patent application No. 2022-164359 filed in Japan on October 12, 2022, which is incorporated by reference in this application. Background Art

[0002] Lithium-ion secondary batteries are high-output / high-energy-density batteries used in small mobile devices such as laptop computers, mobile phones, and smartphones. In recent years, their use in devices that require large capacity, high current, or high voltage, such as power tools, electric bicycles, electric motorcycles, electric vehicles, and household batteries, has been advancing.

[0003] However, since this type of battery uses an organic solvent, there is a risk of fire and smoke when the main body temperature, input and output current, charging voltage, etc. are exceeded, so a protection circuit and protection device using an electronic circuit are generally assembled. In the protection circuit, as a protection device, a FET (Field-Effect Transistor) that performs electrical connection and disconnection, a thermistor that senses temperature, and a fuse that physically cuts off the circuit are used, but most fuses use a fuse with a heating element.

[0004] In addition to the function of cutting off under overcurrent like a general current fuse, the protection device composed of a fuse with a heating element can also melt and cut off the fuse element by heating the heating element when the electronic circuit senses an abnormality. Compared with a general current fuse that only cuts off by overcurrent, this protection device has the advantages of being able to quickly cut off under abnormal conditions, and being able to easily set a safety margin in the circuit that takes into account battery characteristics, usage conditions, etc., and being able to melt and cut off the fuse element at the desired timing.

[0005] Fig.21 FIG. 1 is a diagram showing a configuration example of a surface-mount protection device. Fig.21 (A) is a top view showing the structure with the cover member omitted. Fig.21 (B) is a cross-sectional view. Fig.21 (C) is a bottom view. Fig.21The protection device 100 shown comprises: an insulating substrate 101; a first electrode 102 and a second electrode 103 formed on the surface of the insulating substrate 101; a heating element 104 formed on the surface of the insulating substrate 101; an insulating layer 105 covering the heating element 104; an intermediate electrode 106 stacked on the insulating layer 105 and connected to the heating element 104; a fuse element 107, which is a fusible conductor carried across the first electrode 102, the intermediate electrode 106 and the second electrode 103 via a connecting material 110 composed of various tin-based solder pastes; and a flux 111 coated on the fuse element 107.

[0006] The first electrode 102 and the second electrode 103 are terminal portions connected to the current path of the external circuit to which the protection device 100 is connected, and are respectively connected to the first external connection electrode 102a and the second external connection electrode 103a formed on the back surface of the insulating substrate 101 via the concave-convex structure. In the protection device 100, the first external connection electrode 102a and the second external connection electrode 103a are connected to the connection electrodes provided on the external circuit substrate on which the protection device 100 is mounted, whereby the fuse element 107 is assembled to a part of the current path formed on the external circuit substrate.

[0007] The heating element 104 is a conductive component that has a relatively high resistance value and generates heat when energized, and is composed of, for example, nickel-chromium, W, Mo, Ru, or the like, or a material containing them. In addition, the heating element 104 is connected to a heating element electrode 108 formed on the surface of the insulating substrate 101. The heating element electrode 108 is connected to a third external connection electrode 108a formed on the back side of the insulating substrate 101 via a concave-convex structure. In the protection device 100, the third external connection electrode 108a is connected to a connection electrode provided on an external circuit substrate on which the protection device 100 is installed, thereby connecting the heating element 104 to an external power supply provided in an external circuit. Then, the energization of the heating element 104 is always controlled by a switching device, etc., not shown in the figure.

[0008] The heating element 104 is covered with an insulating layer 105 made of a glass layer or the like, and an intermediate electrode 106 is formed on the insulating layer 105, overlapping the intermediate electrode 106 via the insulating layer 105. In addition, a fuse element 107 is connected to the intermediate electrode 106 via a connecting material 110, which spans the connection between the first electrode 102 and the second electrode 103.

[0009] Thus, the protection device 100 is thermally connected by overlapping the heating element 104 and the fuse element 107 , and when the heating element 104 generates heat by being energized, the fuse element 107 can be melted.

[0010] The fuse element 107 is connected from the first electrode 102 to the second electrode 103 through the intermediate electrode 106, and constitutes a part of the current path of the external circuit in which the protection device 100 is assembled. Then, the fuse element 107 is energized with a current exceeding the rated current, and is melted due to self-heating (Joule heat). Alternatively, the fuse element 107 is melted by the heat of the heating element 104, and its molten conductor is melted by condensing on the first electrode 102, the second electrode 103 and the intermediate electrode 106. As a result, the first electrode 102 and the second electrode 103 are cut off.

[0011] Prior art literature

[0012] Patent Literature

[0013] Patent Document 1: Japanese Patent No. 5072796

[0014] Patent Document 2: Japanese Patent No. 5876346 Summary of the invention

[0015] Problems to be solved by the invention

[0016] In recent years, with the expansion of applications equipped with lithium-ion secondary batteries, they have also begun to be used in large-capacity, high-current, and high-voltage devices. Therefore, protection devices are also required to be high-rated and high-voltage. As a method of reducing the resistance value of the fuse element itself to increase the rated current, the cross-sectional area of ​​the fuse element is usually increased.

[0017] However, by increasing the cross-sectional area of ​​the fuse element, the resistance value of the fuse is reduced, but it will affect the fusing action of the fuse element caused by the heating of the heating element. That is, in the fusing action of the fuse element caused by the heating of the heating element, the melted fuse element infiltrates, spreads and condenses on the intermediate electrode, thereby the fuse element is blown. However, when the cross-sectional area of ​​the fuse element is increased, the fuse element melted by the heating of the heating element cannot be contained on the electrode and overflows, resulting in a situation where the current path cannot be cut off.

[0018] Therefore, an object of the present technology is to provide a protection device that can be quickly and reliably blown even if the cross-sectional area of ​​a fuse element is increased by appropriately applying flux.

[0019] Solutions for solving problems

[0020] When observing the samples of the protection device that cannot cut off the current path, there is a part of the intermediate electrode where the molten fuse element does not wet and expand. This part is the part where the fuse element is not mounted and the part where the flux is not applied. As the reasons why the fuse element does not wet and expand, the oxidation of the molten fuse element progresses due to the lack of flux, and the fluidity and wettability deteriorate. In addition, since this part of the intermediate electrode is not covered by the flux, it becomes impossible to wet due to the degradation of the electrode (oxidation, sulfidation, etc.).

[0021] The inventors of the present application have found that conventionally, by retaining flux in a portion of the fuse element that has not been wetted and spread, the area over which the melted fuse element is wetted and spread is increased, and even a fuse element with a large cross-sectional area can be reliably cut off.

[0022] That is, in order to solve the above-mentioned problems, the protection device of the present technology comprises: an insulating substrate; a heating element, which is arranged on the surface side of the above-mentioned insulating substrate; an insulating layer, which covers the above-mentioned heating element; an intermediate electrode, which is arranged on the above-mentioned insulating layer; a fuse element, which is mounted on the above-mentioned intermediate electrode; a cover member, which covers the surface of the above-mentioned insulating substrate; and a flux, in which a protrusion for holding the above-mentioned flux at a specified position is erected in the above-mentioned cover member in a manner opposite to the above-mentioned intermediate electrode, the above-mentioned intermediate electrode has a length longer than the width of the above-mentioned fuse element in a direction perpendicular to the current-carrying direction of the above-mentioned fuse element, and at least one of the ends of the above-mentioned intermediate electrode extends from the above-mentioned fuse element, and the above-mentioned protrusion is arranged at a position opposite to the position of the above-mentioned intermediate electrode where the above-mentioned fuse element is mounted and at a position opposite to the above-mentioned end where the above-mentioned fuse element is not mounted, so as to hold the above-mentioned flux on the above-mentioned fuse element and the above-mentioned end.

[0023] In addition, the protection device of the present technology comprises: an insulating substrate; an intermediate electrode, which is arranged on the surface side of the above-mentioned insulating substrate; a fuse element, which is mounted on the above-mentioned intermediate electrode; a cover member, which covers the surface of the above-mentioned insulating substrate; a flux; a heating element, which is arranged on the back side opposite to the surface of the above-mentioned insulating substrate; and an insulating layer, which covers the above-mentioned heating element, in which a protrusion for holding the above-mentioned flux at a specified position is erected in the above-mentioned cover member in a manner opposite to the above-mentioned intermediate electrode, the above-mentioned intermediate electrode has a length longer than the width of the above-mentioned fuse element in a direction orthogonal to the current-carrying direction of the above-mentioned fuse element, and at least one of the ends of the above-mentioned intermediate electrode extends from the above-mentioned fuse element, and the above-mentioned protrusion is arranged at a position opposite to the position of the above-mentioned intermediate electrode where the above-mentioned fuse element is mounted and at a position opposite to the above-mentioned end where the above-mentioned fuse element is not mounted, so as to hold the above-mentioned flux on the above-mentioned fuse element and the above-mentioned end.

[0024] In addition, the manufacturing method of the protection device of the present technology comprises: a process of forming a connecting body, wherein the connecting body comprises an insulating substrate, a heating element provided on the surface side of the insulating substrate, an insulating layer covering the heating element, and the intermediate electrode provided on the insulating layer, and a fuse element is mounted on the intermediate electrode; a process of applying flux on the fuse element and the intermediate electrode via a mask having an opening corresponding to the coating area; and a process of connecting a cover member to the surface of the insulating substrate on which the fuse element is mounted to cover the surface of the substrate, wherein a protrusion for holding the flux at a predetermined position is erected in the cover member in a manner opposite to the intermediate electrode, the intermediate electrode having a length longer than the width of the fuse element in a direction orthogonal to the direction of conduction of the fuse element, and at least one of the ends of the intermediate electrode extends from the fuse element, and the protrusion is provided at a position opposite to the position of the intermediate electrode on which the fuse element is mounted and at a position opposite to the end on which the fuse element is not mounted, so as to hold the flux on the fuse element and the end.

[0025] In addition, the manufacturing method of the protection device of the present technology comprises: a process of forming a connecting body, wherein the connecting body has an insulating substrate, the intermediate electrode provided on the surface side of the insulating substrate, a heating element provided on the back side opposite to the surface of the insulating substrate, and an insulating layer covering the heating element, and a fuse element is mounted on the intermediate electrode; a process of applying flux on the fuse element and the intermediate electrode via a mask having an opening corresponding to the coating area; and a process of connecting a cover member to the surface of the insulating substrate on which the fuse element is mounted to cover the substrate surface, wherein a protrusion for holding the flux at a predetermined position is erected in the cover member in a manner opposite to the intermediate electrode, the intermediate electrode has a length longer than the width of the fuse element in a direction orthogonal to the current-carrying direction of the fuse element, and at least one of the ends of the intermediate electrode extends from the fuse element, and the protrusion is provided at a position opposite to the position of the intermediate electrode on which the fuse element is mounted and at a position opposite to the end on which the fuse element is not mounted, so as to hold the flux on the fuse element and the end.

[0026] Effects of the Invention

[0027] According to the present technology, it is possible to provide a protection device that can be quickly and reliably blown even if the fuse element has a large cross-sectional area. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 1 is a diagram showing a configuration example of a protection device in which a heating element is provided on the surface of an insulating substrate. Figure 1 (A) is a top view showing the cover member omitted, Figure 1 (B) is the A-A section view, Figure 1 (C) is the B-B cross-sectional view.

[0029] Figure 2 It means in Figure 1 The diagram shows the state of the fuse element being blown in the protection device shown. Figure 2 (A) is a top view showing the cover member omitted, Figure 2 (B) is the B-B cross-sectional view.

[0030] Figure 3 The figure shows a protection device in which an end protrusion is erected so as to straddle both a position opposite to a position of an intermediate electrode on which a fuse element is mounted and an end portion on which no fuse element is mounted. Figure 3 (A) is a top view showing the cover member omitted, Figure 3 (B) is the A-A cross-sectional view.

[0031] Figure 4 This is a diagram showing a configuration in which the end protrusion is formed to have a smaller diameter than the middle protrusion. Figure 4 (A) is a top view showing the cover member omitted, Figure 4 (B) is the A-A cross-sectional view.

[0032] Figure 5 1 is a diagram showing a configuration in which the end protrusion faces the end of the intermediate electrode and a portion of the end protrudes from the end of the intermediate electrode. Figure 5 (A) is a top view showing the cover member omitted, Figure 5 (B) is the A-A cross-sectional view.

[0033] Figure 6 is a cross-sectional view of a fusible conductor.

[0034] Figure 7 is a cross-sectional view showing the manufacturing process of the protection device, Figure 7 (A) indicates the process of applying flux. Figure 7 (B) represents a connection body coated with flux, Figure 7 (C) represents a protection device.

[0035] Figure 8 This is a circuit diagram showing a configuration example of a battery pack.

[0036] Fig. 9 It is the circuit diagram of the protection device.

[0037] Fig.10 This is a cross-sectional view showing a configuration in which the length of the end protrusion is made longer than the length of the middle protrusion.

[0038] Fig.11This is a diagram showing the state of uneven distribution of flux inside the protection device. Fig.11 (A) is a top view showing the cover member omitted, Fig.11 (B) is the A-A cross-sectional view.

[0039] Fig.12 This is a cross-sectional view showing a state where the molten conductor of the fuse element is aggregated on the intermediate electrode.

[0040] Fig.13 1 is a diagram showing a configuration in which the length of the end protrusion is made longer than the length of the middle protrusion and the diameter of the end protrusion is made smaller than that of the middle protrusion. Fig.13 (A) is a top view showing the cover member omitted, Fig.13 (B) is the A-A cross-sectional view.

[0041] Fig.14 The figure shows a structure in which the length of the end protrusion is longer than the length of the middle protrusion, and the end protrusion is erected so as to straddle both a position opposite to a position of the middle electrode on which a fuse element is mounted and an end on which no fuse element is mounted. Fig.14 (A) is a top view showing the cover member omitted, Fig.14 (B) is the A-A cross-sectional view.

[0042] Fig.15 This is a diagram showing a configuration in which the length of the end protrusion is longer than the length of the middle protrusion and a portion of the protrusion protrudes from the end of the middle electrode. Fig.15 (A) is a top view showing the cover member omitted, Fig.15 (B) is the A-A cross-sectional view.

[0043] Fig.16 is a diagram showing a protective device according to a modified example, Fig.16 (A) is a top view showing the cover member omitted, Fig.16 (B) is the A-A cross-sectional view.

[0044] Fig.17 is a circuit diagram of a protection device according to a modified example.

[0045] Fig.18 1 is a diagram showing a configuration example of a protective device having a heating element on the back side of an insulating substrate. Fig.18 (A) is a top view showing the cover member omitted, Fig.18 (B) is the A-A section view, Fig.18 (C) is the B-B section view, Fig.18 (D) is a bottom view.

[0046] Fig.19 is Fig.18In the protection device shown, a cover member is omitted and a plan view is shown of a state where a fuse element is blown.

[0047] Fig. 20 is a diagram showing a protection device of Comparative Example 1, Fig. 20 (A) is a top view showing the cover member omitted, Fig. 20 (B) is the A-A cross-sectional view.

[0048] Fig.21 FIG. 1 is a diagram showing a configuration example of a surface-mount protection device. Fig.21 (A) is a top view showing the cover member omitted, Fig.21 (B) is a cross-sectional view. Fig.21 (C) is a bottom view. DETAILED DESCRIPTION

[0049] Hereinafter, the protective device to which the present technology is applied is described in detail with reference to the accompanying drawings. It should be noted that the present technology is not limited to the following embodiments, and various changes can be made without departing from the main purpose of the present technology. In addition, the accompanying drawings are schematic, and the ratios of various dimensions may sometimes be different from the actual ratios. The specific dimensions should be determined by referring to the following description. In addition, the drawings also include parts with different dimensional relationships and ratios.

[0050] [First embodiment]

[0051] like Figure 1 (A)~ Figure 1 As shown in (C), the protection device 1 to which the present technology is applied comprises: an insulating substrate 2; a heating element 4, which is arranged on the surface 2a side of the insulating substrate 2; an insulating layer 5, which covers the heating element 4; an intermediate electrode 6, which is arranged on the insulating layer 5; a fuse element 3, which is mounted on the intermediate electrode 6; a cover member 30, which covers the surface 2a of the insulating substrate 2; and a flux 7.

[0052] In the cover member 30, a protrusion 31 for holding the flux 7 at a predetermined position is erected so as to face the intermediate electrode 6. In a direction perpendicular to the current-carrying direction of the fuse element 3, the intermediate electrode 6 has a length longer than the width of the fuse element 3, and at least one of the ends 6a, 6b of the intermediate electrode 6, preferably both ends 6a, 6b, protrudes from the fuse element 3.

[0053] The projections 31 are provided at positions opposite to the positions of the intermediate electrodes 6 where the fuse elements 3 are mounted and at positions opposite to the ends 6a and 6b where the fuse elements 3 are not mounted, and hold the flux 7 on the fuse elements 3 and the ends 6a and 6b.

[0054] Thus, the protection device 1 can also hold the flux 6 in the portion of the intermediate electrode 6 where the fuse element 3 is not mounted, and the area where the melted fuse element 3 spreads increases. Therefore, even if the cross-sectional area of ​​the fuse element 3 is increased, it can be quickly and reliably melted.

[0055] Such a protection device 1 is assembled in an external circuit such as a protection circuit of a lithium-ion secondary battery, whereby the fuse element 3 constitutes a part of the current path of the external circuit, and the current path is cut off by heating of the heating element 4 or melting due to overcurrent exceeding the rated value (see Figure 2 ). Hereinafter, each structure of the protection device 1 will be described in detail.

[0056] [Insulating substrate]

[0057] The insulating substrate 2 is formed of an insulating member such as alumina, glass ceramics, mullite, zirconia, etc. In addition, the insulating substrate 2 may also use a material used for a printed wiring substrate such as an epoxy glass substrate or a phenol substrate. It should be noted that in this specification, the surface of the insulating substrate 2 on which the fuse element 3 is mounted is referred to as the front surface 2a, and the surface opposite to the surface on which the fuse element 3 is mounted is referred to as the back surface 2b.

[0058] [First electrode, second electrode]

[0059] The first electrode 11 and the second electrode 12 are formed at opposite ends of the surface 2a of the insulating substrate 2. The first electrode 11 and the second electrode 12 are respectively formed of a conductive pattern of Ag, Cu, or an alloy thereof. The first electrode 11 and the second electrode 12 can be formed, for example, by printing Ag paste in a predetermined pattern by screen printing and then firing at a predetermined temperature.

[0060] The first electrode 11 is continuous with the first external connection electrode 15 formed on the back side 2b via the concavo-convex structure from the surface 2a of the insulating substrate 2. In addition, the second electrode 12 is continuous with the second external connection electrode 16 formed on the back side 2b via the concavo-convex structure from the surface 2a of the insulating substrate 2. In the surface mounted protection device 1, when the protection device 1 is mounted on an external circuit substrate, the first external connection electrode 15 and the second external connection electrode 16 are connected to the connection electrodes provided on the external circuit substrate, whereby the fuse element 3 is assembled to a part of the current path formed on the external circuit substrate.

[0061] The first electrode 11 and the second electrode 12 are electrically connected to the fuse element 3 by mounting the fuse element 3 via various tin-based solder pastes or other conductive connection materials. Figure 2As shown, with respect to the first electrode 11 and the second electrode 12, the heating element 4 generates heat when energized, causing the fuse element 3 to melt, or a large current exceeding the rated value flows through the protection device 1, causing the fuse element 3 to melt due to its own heat (Joule heat), thereby cutting off the connection.

[0062] [Heat generating element]

[0063] The heating element 4 is a conductive component that has a relatively high resistance value and generates heat when electricity is supplied, and is composed of, for example, nickel-chromium, W, Mo, Ru, etc., or materials containing them. The heating element 4 can be formed by mixing powders of these alloys or compositions or compounds with a resin binder, etc., patterning the mixture in a paste form on the insulating substrate 2 using a screen printing technique, and performing firing. As an example, the heating element 4 can be formed by adjusting a mixed paste of ruthenium oxide paste, silver, and glass paste according to a specified voltage, forming a film at a specified position on the surface 2a of the insulating substrate 2 with a specified area, and then performing a firing treatment under appropriate conditions. In addition, the shape of the heating element 4 can be appropriately designed, but if Figure 1 As shown, in order to maximize the heat generation area, it is preferably set to a substantially rectangular shape according to the shape of the insulating substrate 2.

[0064] In addition, one end 4a of the heating element 4 is connected to the first extraction electrode 17, and the other end 4b is connected to the second extraction electrode 18. The first extraction electrode 17 is extracted from the first heating element electrode 8 formed on one side edge of the surface 2a of the insulating substrate 2. The second extraction electrode 18 is extracted from the second heating element electrode 9 formed on the other side edge of the surface 2a of the insulating substrate 2. The first extraction electrode 17 is extracted from the first heating element electrode 8 along the one end 4a of the heating element 4, and the second extraction electrode 18 is extracted from the second heating element electrode 9 formed on the other side edge of the surface 2a of the insulating substrate 2. Figure 1 In the protective device 1 shown, the second lead electrode 18 extends along one side edge of the heating element 4 formed into a substantially rectangular shape and overlaps one side edge of the heating element 4. Similarly, the second lead electrode 18 is led out from the second heating element electrode 9 along the other end 4b of the heating element 4. Figure 1 In the illustrated protection device 1 , the protection device 1 extends along the other side edge of the heat generating element 4 formed in a substantially rectangular shape and overlaps the other side edge of the heat generating element 4 .

[0065] [Insulation layer]

[0066] Furthermore, the heating element 4, the first extraction electrode 17, and the second extraction electrode 18 are covered with the insulating layer 5. Furthermore, on the insulating layer 5, the intermediate electrode 6 is formed.

[0067] The insulating layer 5 protects and insulates the heating element 4. In order to efficiently transfer the heat of the heating element 4 to the intermediate electrode 6 and the fuse element 3, the insulating layer 5 is formed to be thinner, for example, 10 μm to 40 μm. The insulating layer 5 can be formed, for example, by applying a glass paste and firing it.

[0068] The first heating element electrode 8 and the second heating element electrode 9 are formed on the side edge of the insulating substrate 2 opposite to the side edge where the first electrode 11 and the second electrode 12 are provided. The first heating element electrode 8 is an electrode that serves as a power supply terminal to the heating element 4, is connected to one end 4a of the heating element 4 via the first lead-out electrode 17, and is continuous with the third external connection electrode 10 formed on the back surface 2b of the insulating substrate 2 via a concave-convex structure. The second heating element electrode 9 is connected to the other end 4b of the heating element 4 via the second lead-out electrode 18, and is connected to the intermediate electrode 6.

[0069] The first heating element electrode 8, the second heating element electrode 9, the first lead electrode 17, the second lead electrode 18, and the intermediate electrode 6 can be formed by printing a conductive paste such as Ag or Cu and firing it, similarly to the first electrode 11 and the second electrode 12. In addition, each of these electrodes formed on the surface 2a of the insulating substrate 2 by being composed of the same material can be formed in one or more printing steps and firing steps.

[0070] It should be noted that the first heating element electrode 8 may also be provided with a limiting wall (not shown), which prevents the connection solder provided on the electrode of the external circuit substrate connected to the third external connection electrode 10 from melting during reflow installation, climbing onto the first heating element electrode 8 via the concave-convex structure, and wetting and spreading on the first heating element electrode 8. The first electrode 11 and the second electrode 12 may also be provided with limiting walls in the same manner. The limiting wall may be formed using an insulating material that is not wettable to solder, such as glass, flux resist, or insulating adhesive, and may be formed on the first heating element electrode 8, the first electrode 11, and the second electrode 12 by printing or the like. By providing the limiting wall, the molten connection solder can be prevented from wetting and spreading to the first heating element electrode 8, the first electrode 11, and the second electrode 12, and the connectivity between the protection device 1 and the external circuit substrate can be maintained.

[0071] The intermediate electrode 6 is an electrode that is arranged to extend from the second heating element electrode 9 to the insulating layer 5. One end of the intermediate electrode 6 is connected to the other end 4b of the heating element 4 via the second heating element electrode 9 and the second lead-out electrode 18. In addition, the other end of the intermediate electrode 6 extends to the insulating layer 5 in the region between the first electrode 11 and the second electrode 12, and overlaps with the heating element 4 via the insulating layer 5. Then, the intermediate electrode 6 is connected to the fuse element 3 via a bonding material such as a connecting solder.

[0072] The fuse element 3 is installed across the first motor 11 and the second electrode 12, and is melted by the heat caused by the energization of the heating element 4, or by the self-heating (Joule heat) when the current exceeds the rated current, thereby cutting off the current path between the first electrode 11 and the second electrode 12. In order to prevent oxidation, improve wettability, and achieve rapid melting, the fuse element 3 is coated with flux 7. The structure of the fuse element 3 will be described in detail later.

[0073] It should be noted that it is preferred that a coating such as a Ni / Au plating layer, a Ni / Pd plating layer, a Ni / Pd / Au plating layer, etc. is applied on the surface of the first electrode 11, the second electrode 12, and the intermediate electrode 6 by a known method such as plating treatment. As a result, the protection device 1 can prevent oxidation of the first electrode 11, the second electrode 12, and the intermediate electrode 6, and can prevent the rated change accompanying the increase of the on-resistance. In addition, when the protection device 1 is reflow mounted, the connection solder for connecting the fuse element 3 melts, and the first electrode 11, the second electrode 12, and the intermediate electrode 6 can be prevented from being eroded (solder erosion).

[0074] [Flux]

[0075] Here, the intermediate electrode 6 of the present technology has a length longer than the width of the fuse element 3 in a direction perpendicular to the current-carrying direction of the fuse element 3 when viewed in a plan view, and at least one of the ends 6a and 6b of the intermediate electrode 6 protrudes from the fuse element 3. Then, the flux 7 is held on the fuse element 3 and on the end 6a and / or the end 6b protruding from the fuse element 3 by the protrusion 31 of the cover member 30 described later.

[0076] The direction perpendicular to the direction of conduction of the fuse element 3 is the fusing direction of the fuse element 3, and the fuse element 3 can cut off the current path between the first electrode 11 and the second electrode 12 by fusing in this direction. Then, at least one of the ends 6a and 6b of the intermediate electrode 6 extends in this direction, and the flux 7 is retained on the fuse element 3 and the ends 6a and / or the ends 6b.

[0077] Thus, the protection device 1 can also hold the flux 6 at the end 6a and / or end 6b of the intermediate electrode 6 where the fuse element 3 is not mounted, and can prevent oxidation of the intermediate electrode 6. Therefore, the area where the melted fuse element 3 infiltrates and spreads in the intermediate electrode 6 increases, so that even if the amount of melting increases due to the enlargement of the cross-sectional area of ​​the fuse element 3, it can be quickly and reliably blown. In addition, by quickly blowing the fuse element 3, damage to the intermediate electrode 6 and the heating element 4 itself can be prevented, and the heat interruption operation can be stabilized.

[0078] It should be noted that in order to increase the holding capacity of the intermediate electrode 6 on the molten fuse element 3, as shown in FIG. Figure 1As shown, both end portions 6 a and 6 b of the intermediate electrode 6 preferably extend from the fuse element 3 and hold the flux 7 .

[0079] The flux 7 is applied through the mask 36 having the openings 37 corresponding to the application area, so that a predetermined amount can be applied within a predetermined range (see Figure 7 In this coating process method, a mask such as a metal mask or a screen mask having an opening corresponding to the coating area of ​​the flux 7 is prepared, and the mask is arranged around the coating area of ​​the flux 7 and pressed with a scraper. Thus, the flux 7 of the thickness of the mask can be printed in the opening area of ​​the mask.

[0080] [Cover member]

[0081] The cover member 30 is mounted on the surface 2a of the insulating substrate 2 on which the fuse element 3 is mounted via an adhesive. The cover member 30 protects the interior of the protection device 1 and prevents the molten material from scattering when the fuse element 3 is blown. As a material for the cover member 30, various engineering plastics, ceramics, and other insulating materials can be used.

[0082] The cover member 30 has a protrusion 31 erected on the inner side of the top surface for holding the flux 7 at a predetermined position. The protrusion 31 is provided at a position opposite to the position of the intermediate electrode 6 on which the fuse element 3 is mounted and at a position opposite to the end 6a and / or end 6b on which the fuse element 3 is not mounted, and the protrusion 31 is provided to contact the flux 7 to apply tension, thereby holding the flux 7 on the fuse element 3 and the end 6a and / or end 6b. It should be noted that, as Figure 1 As shown, the protrusions 31 may also be erected at positions opposite to the positions of the intermediate electrodes 6 where the fuse elements 3 are mounted and at positions opposite to the end portions 6a and / or 6b where the fuse elements 3 are not mounted. Figure 3 As shown, it can also be set upright in a manner spanning two positions.

[0083] It should be noted that in this specification, among the multiple protrusions 31 arranged upright, the protrusion at least a portion of which is opposite to the end portions 6a, 6b of the intermediate electrode 6 where the fuse element 3 is not mounted is referred to as an end protrusion 31a, and the protrusion opposite to the position of the intermediate electrode 6 where the fuse element 3 is mounted is referred to as an intermediate protrusion 31b.

[0084] The length of the protrusion 31 is determined by the distance from the intermediate electrode 6 or the fuse element 3. The distance between the end protrusion 31a provided at a position opposite to the end portions 6a, 6b of the intermediate electrode 6 where the fuse element 3 is not mounted and the end portions 6a, 6b of the intermediate electrode 6 is set to a distance that allows the end protrusion 31a to contact the flux 7 and maintain the flux 7, for example, 350 μm or less. Similarly, the distance between the intermediate protrusion 31b provided at a position opposite to the position of the intermediate electrode 6 where the fuse element 3 is mounted and the fuse element 3 is also set to a distance that allows the intermediate protrusion 31b to contact the flux 7 and maintain the flux 7, for example, 350 μm or less.

[0085] In addition, the end protrusion 31a and the middle protrusion 31b need to avoid contact with the molten conductor 3a of the fuse element 3 condensed on the intermediate electrode 6. That is, when the cross-sectional area of ​​the fuse element 3 increases, the amount of the molten conductor 3a of the fuse element 3 held by the intermediate electrode 6 also increases. Therefore, there is a situation where the molten conductor 3a condensed on the intermediate electrode 6 contacts the protrusion 31. As a result, the heat of the heating element 4 is dissipated to the protrusion 31 and the cover member 30 via the molten conductor 3a, which may hinder the heating and melting of the fuse element 3. Therefore, the distance between the end protrusion 31a and the end 6a, 6b of the intermediate electrode 6 and the distance between the middle protrusion 31b and the fuse element 3 has a distance corresponding to the volume of the molten conductor 3a, for example, each is set to be more than 100μm. By having a length that does not contact the molten conductor 3a, the end protrusion 31a and the middle protrusion 31b can prevent the heat of the heating element 4 caused by contact with the molten conductor 3a from being dissipated, and the fuse element 3 can be melted quickly and reliably.

[0086] The shape of the protrusion 31 is not particularly limited, and may be cylindrical, cylindrical, or other columnar shapes. In addition, there are one or more protrusions 31. The surface of the protrusion 31 that contacts the soldering flux 7 may be smooth or rough. The protrusions 31 may all be formed in the same shape and size, or may be partially formed in different shapes and sizes. For example, Figure 4 As shown in FIG. 1 , the end protrusion 31a may be formed to have a smaller diameter than the middle protrusion 31b. Figure 5 As shown in FIG. 1 , the end protrusion 31a may be formed in a shape and size such that the end protrusion 31a faces the end portions 6a and 6b of the intermediate electrode 6 and a portion thereof protrudes from the end portions 6a and 6b. In this way, the flux 7 can be held until it exceeds the end portions 6a and 6b of the intermediate electrode 6. Figure 5 In the illustrated configuration, the end protrusion 31a is formed in an elliptical column shape with the width direction (melting direction) perpendicular to the current-carrying direction of the fuse element 3 as the major axis, but the shape of the end protrusion 31a is not limited thereto.

[0087] The protrusions 31 are arranged along the long dimension of the intermediate electrode 6 and formed above the intermediate electrode 6. Thus, the flux 7 is held along the region of the intermediate electrode 6 heated by the heating element 4. In addition, the arrangement pattern of the protrusions 31 is not particularly limited, and the protrusions 31 may be arranged in a single row or in multiple rows. In addition, in the case of arranging in multiple rows, the protrusions 31 may be arranged in parallel or in a staggered manner.

[0088] In addition, in order to prevent the flux from shifting, the protrusions 31 are preferably arranged at fixed intervals, but the erected intervals may not be fixed. For the same reason, the protrusions 31 are preferably arranged symmetrically in a direction orthogonal to the current-carrying direction of the fuse element when viewed in cross section, but may also be asymmetrical.

[0089] It should be noted that in order to increase the amount of the intermediate electrode 6 that holds the molten fuse element 3, it is preferred that the two end portions 6a, 6b of the intermediate electrode 6 extend from the fuse element 3, and the flux 7 is held to the top of the two end portions 6a, 6b by the end protrusions 31a to prevent oxidation in the entire area of ​​the intermediate electrode 6.

[0090] [Fuse element]

[0091] Next, the fuse element 3 is described. The fuse element 3 is installed across the first electrode 11 and the second electrode 12, and is cut off from the current path between the first electrode 11 and the second electrode 12 by the heat generated by the energization of the heating element 4 or by the self-heating (Joule heat) caused by the energization of a current exceeding the rated value.

[0092] The fuse element 3 can be made of any conductive material that melts due to the heat caused by the energization of the heating element 4 or an overcurrent state, for example, SnAgCu-based Pb-free solder, BiPbSn alloy, BiPb alloy, BiSn alloy, SnPb alloy, PbIn alloy, ZnAl alloy, InSn alloy, PbAgSn alloy, etc.

[0093] In addition, the fuse element 3 may also be a structure containing a high melting point metal and a low melting point metal. Figure 6 As shown, the fuse element 3 is a laminated structure composed of an inner layer and an outer layer, and has a low melting point metal layer 13 as the inner layer and a high melting point metal layer 14 as the outer layer laminated on the low melting point metal layer 13. The fuse element 3 is connected to the first electrode 11, the second electrode 12 and the intermediate electrode 6 via a conductive connection material such as a connection solder.

[0094] The low melting point metal layer 13 is preferably a metal with solder or Sn as the main component, which is a material generally referred to as "Pb-free solder". The melting point of the low melting point metal layer 13 does not necessarily need to be higher than the temperature of the reflow furnace, and it can also melt at about 200°C. The high melting point metal layer 14 is a metal layer stacked on the surface of the low melting point metal layer 13, such as Ag or Cu or a metal with any of them as the main component, and has a high melting point that does not melt even when the first electrode 11, the second electrode 12, and the intermediate electrode 6 are connected to the fuse element 3 by reflow, and the protection device 1 is installed on the external circuit substrate.

[0095] Such a fuse element 3 can be formed by forming a high melting point metal layer on a low melting point metal foil using a plating technique, or can also be formed using other well-known lamination techniques or film formation techniques. In this case, the fuse element 3 can be configured such that the entire surface of the low melting point metal layer 13 is covered by the high melting point metal layer 14, or can be configured such that the high melting point metal layer 14 is covered except for a pair of opposite side surfaces. It should be noted that the fuse element 3 can also be configured such that the high melting point metal layer 14 is used as an inner layer and the low melting point metal layer 13 is used as an outer layer. In addition, the fuse element 3 can also be formed by a multilayer structure of three or more layers in which the low melting point metal layer 13 and the high melting point metal layer 14 are alternately stacked, and an opening is provided in a part of the outer layer to expose a part of the inner layer.

[0096] The fuse element 3 is formed by laminating the high melting point metal layer 14 as an outer layer on the low melting point metal layer 13 as an inner layer, so that the fuse element 3 can maintain its shape and not be melted even when the reflow temperature exceeds the melting temperature of the low melting point metal layer 13. Therefore, the first electrode 11, the second electrode 12, and the intermediate electrode 6 can be efficiently connected to the fuse element 3 and the protection device 1 can be mounted on the external circuit board by reflow. In addition, the reflow can also prevent the fuse element 3 from changing its fusing characteristics, such as not fusing at a predetermined temperature or fusing at a temperature lower than a predetermined temperature, due to the resistance value of the fuse element 3 becoming locally higher or lower due to deformation.

[0097] In addition, the fuse element 3 does not melt due to self-heating during the period when the specified rated current flows. Then, when a current higher than the rated value flows, it melts due to self-heating, cutting off the current path between the first electrode 11 and the second electrode 12. In addition, the heating element 4 melts due to the heat generated by the power supply, cutting off the current path between the first electrode 11 and the second electrode 12.

[0098] At this time, in the fuse element 3, the high melting point metal layer 14 is eroded (solder erosion) by the molten low melting point metal layer 13, and the high melting point metal layer 14 melts at a temperature lower than the melting temperature. Therefore, the fuse element 3 can be blown in a short time by the erosion of the high melting point metal layer 14 by the low melting point metal layer 13. In addition, since the molten conductor 3a of the fuse element 3 is disconnected by the physical pulling action of the intermediate electrode 6 and the first electrode 11 and the second electrode 12, the current path between the first electrode 11 and the second electrode 12 can be quickly and reliably cut off ( Figure 2 ).

[0099] In addition, the volume of the low melting point metal layer 13 of the fuse element 3 is preferably formed to be larger than the volume of the high melting point metal layer 14. The fuse element 3 is heated by self-heating caused by overcurrent or heating of the heating element 4, and the high melting point metal is eroded by melting of the low melting point metal, thereby being able to melt and fuse quickly. Therefore, by forming the volume of the low melting point metal layer 13 to be larger than the volume of the high melting point metal layer 14, the fuse element 3 can promote the erosion effect and quickly cut off the first electrode 11 and the second electrode 12.

[0100] In addition, since the fuse element 3 is formed by stacking a high melting point metal layer 14 on a low melting point metal layer 13 as an inner layer, the fusing temperature can be greatly reduced compared to conventional chip fuses made of high melting point metals. Therefore, the fuse element 3 can have a larger cross-sectional area and a significantly higher rated current than chip fuses of the same size. In addition, compared to conventional chip fuses with the same rated current, it can be miniaturized and thinned, and has excellent rapid fusing properties.

[0101] In addition, the fuse element 3 can improve the resistance (pulse resistance) to surges of abnormally high voltages applied instantaneously in the electrical system in which the protection device 1 is assembled. That is, the fuse element 3 will not melt even in a case where, for example, a current of 100A flows for several msec. In this regard, since a large current flowing in a very short time flows on the surface of the conductor (skin effect), the fuse element 3 is provided with a high melting point metal layer 14 such as an Ag plating layer with a low resistance value as an outer layer, so that the current applied by the surge can flow easily and can prevent melting due to self-heating. Therefore, compared with the conventional fuse composed of solder alloy, the fuse element 3 can greatly improve the resistance to surges.

[0102] [Manufacturing process of protection device]

[0103] Next, a manufacturing process of the protection device 1 will be described. Figure 7 is a cross-sectional view showing a manufacturing process of the protection device 1, Figure 7 (A) indicates the process of applying flux. Figure 7(B) shows a connection body 35 coated with flux, Figure 7 (C) represents a protection device 1. The manufacturing process of the protection device 1 includes: a process of forming a connection body 35 connected to a fuse element 3 on an intermediate electrode 6, wherein the connection body 35 has an insulating substrate 2, a heating element 4 provided on the surface 2a side of the insulating substrate 2, an insulating layer 5 covering the heating element 4, and an intermediate electrode 6 provided on the insulating layer 5; a process of applying a soldering flux 7 on the fuse element 3 via a mask 36 having an opening corresponding to a coating area; and a process of connecting a cover member 30 to the surface 2a of the insulating substrate 2 on which the fuse element 3 is mounted to cover the substrate surface.

[0104] As described above, on the surface 2a of the insulating substrate 2, a conductive paste such as Ag or Cu is printed using screen printing technology and fired to form the first electrode 11, the second electrode 12, the first heating element electrode 8, the second heating element electrode 9, the first lead electrode 17, and the second lead electrode 18.

[0105] In addition, the heating element 4 is made of nickel-chromium, W, Mo, Ru, etc. or materials containing them, and can be formed by mixing powders of these alloys or compositions or compounds with a resin binder, etc., patterning the mixture in a paste form on the insulating substrate 2 using a screen printing technique, etc., and then firing the mixture. On the heating element 4, the first lead electrode 17, and the second lead electrode 18, a glass-based paste is applied using a screen printing technique, etc., and then fired, thereby forming the insulating layer 5.

[0106] Furthermore, by printing Ag, Cu or other conductive paste using screen printing technology and firing it, the intermediate electrode 6 is formed from the second heating element electrode 9 to the insulating layer 5. After printing the conductive connection material such as connecting solder and mounting the fuse element 3, the first electrode 11, the second electrode 12 and the intermediate electrode 6 are delivered to the reflow process. Thus, the connection body 35 connected with the fuse element 3 is obtained.

[0107] Next, the flux 7 is applied to the fuse element 3 via a mask 36 (metal mask, screen mask, etc.) having an opening 37 corresponding to the application area. Figure 7 As shown in (A), in the screen printing process, a mask 36 having an opening 37 corresponding to the printed portion is arranged around the printed portion of the flux 7, and a scraper 38 is slid on the surface of the mask 36, thereby applying the flux 7 (the thickness of the mask 36) at a position and area corresponding to the opening 37. Figure 7 (B)).

[0108] Next, a cover member 30 is connected to the surface 2a of the insulating substrate 2 on which the fuse element 3 is mounted to cover the substrate surface, thereby obtaining a protection device 1 ( Figure 7(C)). At this time, by providing the protrusion 31 on the cover member 30, the flux 7 is attracted by the surface tension of the flux 7 in contact with the tip of the protrusion 31, and the flux 7 can be held at a predetermined position.

[0109] [Circuit Configuration Example]

[0110] Such a protection device 1 is used, for example, by being assembled into a circuit in a battery pack 20 of a lithium-ion secondary battery. Figure 8 As shown, the battery pack 20 includes a battery stack 25 composed of a total of four battery cells 21 a to 21 d of lithium-ion secondary batteries, for example.

[0111] The battery pack 20 includes: a battery stack 25; a charge and discharge control circuit 26 for controlling the charge and discharge of the battery stack 25; a protection device 1 that applies the present invention for cutting off the charge and discharge path when an abnormality occurs in the battery stack 25; a detection circuit 27 for detecting the voltage of each battery cell 21a to 21d; and a current control device 28, which is a switching device that controls the action of the protection device 1 according to the detection result of the detection circuit 27.

[0112] The battery stack 25 is formed by connecting battery cells 21a to 21d in series, which need to be controlled to protect it from overcharge and overdischarge, and is detachably connected to the charging device 22 via the positive terminal 20a and the negative terminal 20b of the battery pack 20, so that the charging voltage from the charging device 22 is applied. The battery pack 20 charged by the charging device 22 can be operated by connecting the positive terminal 20a and the negative terminal 20b to an electronic device operated by the battery.

[0113] The charge and discharge control circuit 26 includes: two current control devices 23a and 23b connected in series to the current path between the battery stack 25 and the charging device 22; and a control unit 24 that controls the operation of these current control devices 23a and 23b. The current control devices 23a and 23b are composed of, for example, field effect transistors (hereinafter referred to as FETs), and the control unit 24 controls the gate voltage to control the conduction and interruption of the current path of the battery stack 25 in the charging direction and / or the discharging direction. The control unit 24 receives power supply from the charging device 22 and operates. Based on the detection result obtained by the detection circuit 27, the control unit 24 controls the operation of the current control devices 23a and 23b in a manner that interrupts the current path when the battery stack 25 is over-discharged or over-charged.

[0114] The protection device 1 is connected to the charge and discharge current path between the battery stack 25 and the charge and discharge control circuit 26 , for example, and its operation is controlled by the current control device 28 .

[0115] The detection circuit 27 is connected to each battery cell 21a to 21d, detects the voltage value of each battery cell 21a to 21d, and supplies each voltage value to the control unit 24 of the charge and discharge control circuit 26. In addition, when any of the battery cells 21a to 21d reaches an overcharge voltage or an overdischarge voltage, the detection circuit 27 outputs a control signal for controlling the current control device 28.

[0116] The current control device 28 is composed of, for example, a FET, and according to the detection signal output from the detection circuit 27, when the voltage value of the battery cells 21a~21d becomes a voltage exceeding the specified over-discharge or over-charge state, the protection device 1 is activated, and the charge and discharge current path of the battery stack 25 is cut off regardless of the switching action of the current control devices 23a and 23b.

[0117] The protection device 1 to which the present invention is applied and used in the battery pack 20 having the above-mentioned structure has the following features: Fig. 9 The circuit configuration shown. That is, with respect to the protection device 1, the first external connection electrode 15 is connected to the battery stack 25 side, and the second external connection electrode 16 is connected to the positive terminal 20a side, whereby the fuse element 3 is connected in series to the charge and discharge path of the battery stack 25. In addition, with respect to the protection device 1, the heating element 4 is connected to the current control device 28 via the first heating element electrode 8 and the third external connection electrode 10, and the heating element 4 is connected to the battery stack 25. In this way, one end of the heating element 4 is connected to the fuse element 3 and one end of the battery stack 25 via the intermediate electrode 6, and the other end is connected to the current control device 28 and the other end of the battery stack 25 via the third external connection electrode 10. Thus, a power supply path to the heating element 4 is formed, in which power supply can be controlled by the current control device 28.

[0118] [Action of protection device]

[0119] When the detection circuit 27 detects an abnormal voltage in any of the battery cells 21a to 21d, a cutoff signal is output to the current control device 28. Then, the current control device 28 controls the current to energize the heating element 4. As for the protection device 1, the current flows from the battery stack 25 to the heating element 4, whereby the heating element 4 starts to generate heat. As for the protection device 1, the fuse element 3 is blown due to the heat generated by the heating element 4, thereby cutting off the charge and discharge path of the battery stack 25. In addition, the protection device 1 is formed by making the fuse element 3 contain a high melting point metal and a low melting point metal. The low melting point metal melts before the high melting point metal melts, and the fuse element 3 can be melted in a short time by utilizing the corrosion effect of the molten low melting point metal on the high melting point metal.

[0120] Since the protection device 1 cuts off the power supply path to the heating element 4 by melting the fuse element 3 , the heating element 4 stops generating heat.

[0121] It should be noted that, in the protection device 1 , when an overcurrent exceeding the rated value is supplied to the battery pack 20 , the fuse element 3 also melts due to self-heating, thereby interrupting the charge and discharge path of the battery pack 20 .

[0122] In this way, in the protection device 1, the fuse element 3 is melted by the heat caused by the energization of the heating element 4 or the self-heating of the fuse element 3 caused by the overcurrent. At this time, when the protection device 1 is reflow mounted on the circuit board and the circuit board mounted with the protection device 1 is further exposed to a high temperature environment such as reflow heating, the deformation of the fuse element 3 can be suppressed by having a structure in which the low melting point metal is covered with the high melting point metal. Therefore, the change of the fusing characteristics caused by the change of the resistance value caused by the deformation of the fuse element 3 can be prevented, and the fuse element 3 can be quickly melted by the specified overcurrent and the heat of the heating element 4.

[0123] The protection device 1 of the present invention is not limited to being used in a battery pack of a lithium-ion secondary battery, but can be applied to various uses that require interruption of a current path by an electrical signal.

[0124] [Second embodiment]

[0125] Next, a second embodiment of a protection device to which the present technology is applied will be described. In the following description, the same components as those of the protection device 1 described above are denoted by the same reference numerals and the details may be omitted.

[0126] like Fig.10 As shown, the length of the end protrusion 31 a of the protection device 50 of the second embodiment is longer than the length of the middle protrusion 31 b.

[0127] Even when a plurality of protrusions 31 are provided in an upright position, when the thickness of the fuse element 3 is changed or when the viscosity of the flux is low, the holding force of the protrusions 31 on the flux 7 may be insufficient depending on the intervals between the protrusions 31, and the flux 7 may shift to one side (see FIG. Fig.11 ). Therefore, the end 6a or the end 6b of the intermediate electrode 6 on the side where the flux 7 is not held is oxidized by the heating of the heating element 4, and the molten conductor 3a is not wetted, and the molten conductor 3a of the enlarged fuse element 3 overflows, which may hinder the melting.

[0128] Therefore, in the protection device 50 , the end protrusion 31 a facing the end 6 a and / or end 6 b of the intermediate electrode 6 where the flux 7 may be insufficient due to uneven distribution of the flux 7 is longer than the middle protrusion 31 b .

[0129] As a result, the distance between the end protrusion 31a of the protection device 50 and the end portions 6a, 6b of the intermediate electrode 6 does not become too large, and the holding force of the end protrusion 31a on the flux 7 can be maintained to prevent uneven distribution. Therefore, the flux 7 can be held between the two end portions 6a, 6b of the intermediate electrode 6, and the reduction in wettability due to insufficient flux 7 can be prevented, so that the fuse element 3 can be quickly and reliably blown.

[0130] Here, in the protection device 50, similarly to the protection device 1, it is preferred that the protrusions 31 (i.e., the end protrusions 31a and the middle protrusions 31b) have a length that does not contact the molten fuse element 3. If the protrusions 31 are shortened to avoid contact with the molten conductor 3a of the fuse element 3, the intervals between the protrusions 31 and the fuse element 3 and the ends 6a and 6b of the middle electrode 6 will increase, and the holding force of the flux 7 will decrease. In particular, if Fig.11 As shown, since the distance between the end portions 6a and 6b of the intermediate electrode 6 where no fuse element 3 is mounted and the end protrusion 31a is widened, there is a possibility that the distribution of the flux 7 may be uneven inside the protection device.

[0131] Here, if Fig.12 As shown in FIG. 1 , the molten conductor 3a of the fuse element 3 aggregated on the intermediate electrode 6 is highest at the center of the intermediate electrode 6 and gradually becomes lower toward the ends 6a and 6b of the intermediate electrode 6. The intermediate protrusion 31b of the protection device 50 that faces the molten conductor 3a aggregated on the center of the intermediate electrode 6 is short, and prevents contact with the aggregate of the molten conductor 3a. In addition, the end protrusions 31a that face the two ends 6a and 6b of the intermediate electrode 6 are formed to be long, but the formation position of the end protrusions 31a corresponds to the portion where the height of the aggregate of the molten conductor 3a is low. Therefore, the protection device 50 can maintain the holding force of the flux 7 and prevent uneven distribution by making the length of the end protrusions 31a longer than the intermediate protrusions 31b, and can prevent the heat of the heat generating body 4 from being dissipated due to the contact between the end protrusions 31a and the intermediate protrusions 31b and the molten conductor 3a, so that the fuse element 3 can be quickly and reliably melted.

[0132] It should be noted that in the configuration in which the end protrusion 31a is longer than the middle protrusion 31b, Fig.13 As shown in FIG. 1 , the end protrusion 31a is formed to have a smaller diameter than the middle protrusion 31b. In addition, the end protrusion 31a can be erected at a position opposite to the position of the middle electrode 6 where the fuse element 3 is mounted and at a position opposite to the ends 6a and 6b where the fuse element 3 is not mounted, as shown in FIG. Fig.14 In this case, the end protrusion 31a may be formed in a stepped shape so that the portion facing the position of the intermediate electrode 6 on which the fuse element 3 is mounted is as short as the middle protrusion 31b, and the portion facing the ends 6a and 6b of the intermediate electrode 6 is longer than the middle protrusion 31b. Fig.15 As shown, the end protrusion 31a may be longer than the middle protrusion 31b and formed to face the ends 6a, 6b of the middle electrode 6 and partially extend from the ends 6a, 6b. Thus, the flux 7 can be held to a position beyond the ends 6a, 6b of the middle electrode 6. Fig.15 The end protrusion 31a shown is formed in an elliptical column shape with the width direction (melting direction) perpendicular to the current-carrying direction of the fuse element 3 as the major axis, but the shape of the end protrusion 31a is not limited thereto.

[0133] [Modification 1]

[0134] Next, a modified example of the protection device to which the present technology is applied is described. It should be noted that in the following description, the same reference numerals are sometimes used to indicate the same components as those of the above-mentioned protection devices 1 and 50, and the details thereof are omitted. Fig.16 (A) Fig.16 As shown in (B), the protection device 60 may also independently form a power supply path to the heating element 4 and a current path to the fuse element 3. Fig.16 For the protection device 60 shown, the intermediate electrode 6 and the second heating element electrode 9 are set to be non-connected. In addition, the second heating element electrode 9 is continuous with the fourth external connection electrode 61 formed on the back side 2b of the insulating substrate 2 via a concave-convex structure, just like the first heating element electrode 8. The third external connection electrode 10 and the fourth external connection electrode 61 are connected to the connection electrode provided on the external circuit substrate on which the protection device 60 is installed, thereby connecting the heating element 4 to an external power supply provided in the external circuit. The other structures are the same as those of the protection device 1.

[0135] Fig.17 : is a diagram showing the circuit structure of the protection device 60. As for the protection device 60, by being installed in an external circuit, the first external connection electrode 15 is connected to the battery stack 25 side, and the second external connection electrode 16 is connected to the positive terminal 20a side, so that the fuse element 3 is connected in series to the charge and discharge path of the battery stack 25. The heating element 4 is connected to the current control device 28 via the first heating element electrode 8 and the third external connection electrode 10, and is connected to the battery stack 25. In addition, the heating element 4 is connected to the ground (not shown) via the second heating element electrode 9 and the fourth external connection electrode 61. Thus, a power supply path to the heating element 4 is formed, in which power supply can be controlled by the current control device 28. When the fuse element 3 is blown, the protection device 60 stops the power supply to the heating element 4 through the detection circuit 27 and the current control device 28 that sense the blowing of the fuse element 3.

[0136] The protection device 60 has the protrusions 31 formed therein similarly to the protection devices 1 and 50 , and the flux 7 is held at a predetermined position by the protrusions 31 , thereby achieving the same functions and effects as those of the protection devices 1 and 50 .

[0137] [Modification 2]

[0138] Next, a second modification of the protection device to which the present technology is applied will be described. Note that in the following description, the same reference numerals may be used to denote the same configurations as those of the protection devices 1 , 50 , and 60 described above, and the details thereof may be omitted. Fig.18 FIG. 1 is a diagram showing a protective device 70 according to a modified example. Fig.18 (A) is a top view showing the cover member omitted, Fig.18 (B) is Fig.18 The AA cross-sectional view shown in (A) is Fig.18 (C) is Fig.18 The BB cross-sectional view shown in (A) is Fig.18 (D) is a bottom view.

[0139] like Fig.18 (A)~ Fig.18 As shown in (D), the protection device 70 of the second variant has a heating element 4, a first extraction electrode 17, a second extraction electrode 18, and an insulating layer 5 covering them formed on the back surface 2b opposite to the surface 2a of the insulating substrate 2. In addition, a first heating element electrode 8, a second heating element electrode 9, a first external connection electrode 15, and a second external connection electrode 16 are formed on the back surface 2b of the insulating substrate 2.

[0140] Furthermore, a first electrode 11 , a second electrode 12 , and an intermediate electrode 6 are formed on the surface 2 a of the insulating substrate 2 , and the fuse element 3 is mounted on each of these electrodes 11 , 12 , and 6 .

[0141] The first electrode 11, the second electrode 12 and the intermediate electrode 6 provided on the surface 2a of the insulating substrate 2, the heating element 4, the first lead-out electrode 17, the second lead-out electrode 18, the first heating element electrode 8, the second heating element electrode 9, and the first external connection electrode 15 and the second external connection electrode 16 provided on the back side 2b of the insulating substrate 2 can be formed by the same process as the above-mentioned protection device 1.

[0142] The second heating element electrode 9 and the intermediate electrode 6 are electrically connected through the concavo-convex structure formed on the side of the insulating substrate 2, the conductive through hole penetrating the insulating substrate 2, and the like. That is, the intermediate electrode 6 is electrically and thermally connected to the heating element 4 via the second heating element electrode 9. Thus, in terms of the protection device 70, the heating element 4 heats the intermediate electrode 6 via the insulating substrate 2, and the heat of the heating element 4 is transferred to the intermediate electrode 6 via the second heating element electrode 9 and the concavo-convex structure having excellent thermal conductivity, thereby heating and melting the fuse element 3 ( Fig.19 ).

[0143] It should be noted that in the protection device 70, since the first heating element electrode 8 and the second heating element electrode 9 also become external connection electrodes connected to the electrodes of the external circuit substrate, the third external connection electrode 10 provided on the protection device 1 and the fourth external connection electrode 61 provided on the protection device 60 are not provided.

[0144] The protection device 70 has the protrusions 31 formed therein similarly to the protection devices 1 , 50 , and 60 , and the flux 7 is held at a predetermined position by the protrusions 31 , thereby achieving the same functions and effects as the protection devices 1 , 50 , and 60 .

[0145] Note that, in the protection device 70 , similarly to the protection device 60 , the intermediate electrode 6 and the second heating element electrode 9 may be disconnected to form a power supply path to the heating element 4 and a current path to the fuse element 3 independently.

[0146] Example

[0147] [First embodiment]

[0148] Next, examples of the present technology will be described. In the first example, samples of protection devices with different numbers of protrusions were produced, and a power of 33 W was applied to the heating element to perform a melting test of the fuse element.

[0149] The protection device samples of the embodiment and the comparative example have the same structure as the protection device 1 except for the number of protrusions provided on the cover member. In addition, each sample uses a fuse element with a thickness of 100 μm. Then, a mask having an opening corresponding to the flux coating area of ​​the protection device of the embodiment and the comparative example is used to apply a predetermined amount of flux within a predetermined range.

[0150] For the protection devices of the embodiment and the comparative example, the average melting time (seconds), the minimum / maximum melting time (seconds) and the non-cutting occurrence rate (%) were calculated. The number of samples n of the protection devices of the embodiment and the comparative example was 192. It should be noted that the non-cutting occurrence rate (%) refers to the occurrence rate of samples in which the fuse element does not melt even after a specified time has passed, which is caused by the oxidation of the fuse element and the intermediate electrode, which hinders melting and cannot be melted.

[0151] [Example 1]

[0152] In the first embodiment, four cylindrical protrusions of the same size are formed in a row on the top surface of the cover member along the intermediate electrode. The end protrusions at both ends are erected so as to span the positions opposite to the position of the intermediate electrode where the fuse element is mounted and the position opposite to the end where the fuse element is not mounted (see Figure 3). Depending on the formation position of the protrusion, the flux is applied and held on the fuse element and both end sides of the intermediate electrode extending from the fuse element.

[0153] [Example 2]

[0154] In Example 2, five cylindrical protrusions of the same size are formed in a row on the top surface of the cover member along the intermediate electrode. The protrusions are respectively erected at positions opposite to the position of the intermediate electrode where the fuse element is mounted and at positions opposite to the end portion where the fuse element is not mounted (see Figure 1 ). Depending on the formation position of the protrusion, the flux is applied to the fuse element and the entire area of ​​both ends of the intermediate electrode extending from the fuse element, and is maintained from the fuse element to the top of the end of the intermediate electrode.

[0155] [Comparative Example 1]

[0156] like Fig. 20 As shown, in the protection device of Comparative Example 1, three cylindrical protrusions of the same size are formed in a row along the intermediate electrode on the top surface of the cover member. The protrusions are only erected at the position opposite to the position of the intermediate electrode where the fuse element is mounted. Due to the formation position of the protrusions, the flux is only applied and retained on the fuse element 3.

[0157] [Table 1]

[0158]

[0159] As shown in Table 1, the protection devices of Examples 1 and 2 are capable of applying and maintaining flux to both end sides of the intermediate electrode by also providing protrusions at positions opposite to the ends of the intermediate electrodes extending from the fuse element, and both the melting time and the non-cutting occurrence rate are good results.

[0160] The protrusion of Comparative Example 1 is only erected at a position opposite to the fuse element, and no flux is maintained at both ends of the intermediate electrode. Therefore, the amount of flux applied is relatively small, and due to the heating of the heating element, oxidation of both ends of the fuse element and the intermediate electrode progresses, the melting time becomes longer, and the occurrence rate of non-cutting also increases.

[0161] It should be noted that when comparing Example 1 with Example 2, the number of protrusions and the amount of flux applied are large, and the flux is applied to the tip of the end of the intermediate electrode and maintained, and the melting time and the non-cutting occurrence rate of Example 2 are relatively favorable results.

[0162] [Second embodiment]

[0163] Next, a second embodiment is described. In the second embodiment, samples of protection devices with different protrusion lengths were produced, and a power of 33 W was applied to the heating element to perform a blowout test of the fuse element.

[0164] The protection device samples of the embodiment and the comparative example have the same structure as the protection device 1 except for the length of the protrusion provided on the cover member. In addition, each sample uses a fuse element with a thickness of 125 μm. Then, a mask having an opening corresponding to the flux coating area of ​​the protection device of the embodiment and the comparative example is used to apply a predetermined amount of flux within a predetermined range.

[0165] [Example 3]

[0166] In Example 3, five cylindrical protrusions are formed in a row along the intermediate electrode on the top surface of the cover member. The middle protrusion formed at the position opposite to the position where the fuse element is mounted is shorter than the end protrusion formed at the position opposite to the end of the intermediate electrode where the fuse element is not mounted (see Fig.10 The distance between the end protrusion and the end of the intermediate electrode is set to a distance that can hold the flux therebetween (approximately 350 μm or less), and the distance between the intermediate protrusion and the fuse element is set to a distance that does not contact the molten conductor of the fuse element (approximately 100 μm or more).

[0167] [Comparative Example 2]

[0168] Comparative Example 2 has the same structure as Example 3 except that five cylindrical protrusions of the same size are formed in a row along the intermediate electrode on the top surface of the cover member (see Figure 1 ). For each protrusion, the distance between the end protrusion and the end of the intermediate electrode is set to a distance (approximately 350 μm or less) that allows the flux to be held therebetween.

[0169] [Comparative Example 3]

[0170] Comparative Example 3 has the same structure as Example 3 except that five cylindrical protrusions of the same size are formed in a row along the intermediate electrode on the top surface of the cover member (see Fig.11 Each protrusion is set to have a distance (approximately 100 μm or more) that does not contact the molten conductor of the fuse element.

[0171] [Table 2]

[0172]

[0173] As shown in Table 2, in Example 3, the end protrusion is made to have a length that can hold the flux between the end of the intermediate electrode, and the flux is applied to the fuse element and the two ends of the intermediate electrode extending from the fuse element, so that oxidation of the intermediate electrode can be prevented and the molten conductor can be fully held at both ends. In addition, since the intermediate protrusion does not contact the molten fuse element 3, heat absorption by the protrusion and the cover member can be prevented, and the melting time and the non-cutting occurrence rate are good results.

[0174] In Comparative Example 2, all protrusions are formed with a length that allows the end protrusion to maintain the flux between the end of the intermediate electrode, and the distance between the intermediate protrusion and the fuse element becomes shorter (approximately less than 100 μm), the melted fuse element abuts against the intermediate protrusion, the heat of the heating element is dissipated to the cover member, the temperature of the fuse element decreases, the melting time becomes longer, and the non-cutting rate also increases. It can be seen from this that when the distance between the protrusion and the fuse element becomes shorter by thickening the fuse element, there is a risk that the molten conductor of the fuse element will come into contact with the intermediate protrusion, so it is required to ensure a distance corresponding to the volume (melting amount) of the fuse element (at least 100 μm or more).

[0175] In Comparative Example 3, by shortening the length of all the protrusions provided upright, the flux holding force is reduced, causing flux deviation. As a result, one end of the intermediate electrode is oxidized by the heating of the heating element, so the holding capacity of the molten conductor is reduced, the melting time is prolonged, and the non-cutting rate is also increased.

[0176] Description of Reference Numerals

[0177] 1: protection device; 2: insulating substrate; 2a: surface; 2b: back; 3: fuse element; 3a: melting conductor; 4: heating element; 5: insulating layer; 6: intermediate electrode; 6a: one end; 6b: the other end; 7: soldering flux; 8: first heating element electrode; 9: second heating element electrode; 10: third external connection electrode; 11: first electrode; 12: second electrode; 13: low melting point metal; 14: high melting point metal; 15: first external connection electrode; 16: second external connection electrode; 17: first lead Electrode; 18: second lead-out electrode; 20: battery pack; 21: battery cell; 22: charging device; 23: current control device; 24: control unit; 25: battery stack; 26: charge and discharge control circuit; 27: detection circuit; 28: current control device; 30: cover member; 31: protrusion; 31a: end protrusion; 31b: middle protrusion; 35: connector; 36: mask; 37: opening; 38: scraper; 50: protection device; 60: protection device; 61: fourth external connection electrode; 70: protection device.

Claims

1. A protection device having: Insulating substrate; A heating element is disposed on the surface side of the insulating substrate; An insulating layer covering the heating element; An intermediate electrode, disposed on the insulating layer; a fuse element mounted on the intermediate electrode; a cover member covering a surface of the insulating substrate; as well as Flux, A protrusion for holding the flux at a predetermined position is erected on the cover member so as to face the intermediate electrode. The intermediate electrode has a length longer than a width of the fuse element in a direction perpendicular to a current-carrying direction of the fuse element, and at least one of the ends of the intermediate electrode extends out from the fuse element. The protrusion is provided at a position facing a position of the intermediate electrode where the fuse element is mounted and at a position facing the end of the intermediate electrode where the fuse element is not mounted, and holds the flux on the fuse element and the end.

2. The protection device according to claim 1, wherein: The protrusion has a length that does not come into contact with the molten fuse element.

3. The protection device according to claim 1 or 2, wherein: The length of the protrusion provided at a position facing the end portion where the fuse element is not mounted is longer than the length of the protrusion formed at a position facing a position where the fuse element is mounted.

4. The protection device according to claim 1 or 2, wherein: Both ends of the intermediate electrode extend from the fuse element in a direction orthogonal to the current-carrying direction of the fuse element. The protrusion is provided at a position facing the two end portions.

5. The protection device according to claim 1 or 2, wherein: The protrusions are symmetrically arranged in a direction orthogonal to a current-carrying direction of the fuse element.

6. A protection device having: Insulating substrate; An intermediate electrode is provided on the surface side of the insulating substrate; a fuse element mounted on the intermediate electrode; a cover member covering a surface of the insulating substrate; Flux; a heating element disposed on a back side opposite to the front side of the insulating substrate; and an insulating layer, covering the heating element, A protrusion for holding the flux at a predetermined position is erected on the cover member so as to face the intermediate electrode. The intermediate electrode has a length longer than a width of the fuse element in a direction perpendicular to a current-carrying direction of the fuse element, and at least one of the ends of the intermediate electrode extends out from the fuse element. The protrusion is provided at a position facing a position of the intermediate electrode where the fuse element is mounted and at a position facing the end of the intermediate electrode where the fuse element is not mounted, and holds the flux on the fuse element and the end.

7. A method for manufacturing a protection device, comprising: A process for forming a connected body, wherein: The connection body comprises an insulating substrate, a heating element provided on the surface side of the insulating substrate, an insulating layer covering the heating element, and an intermediate electrode provided on the insulating layer, wherein a fuse element is mounted on the intermediate electrode; A step of applying flux on the fuse element and the intermediate electrode via a mask having an opening corresponding to a coating area; as well as a step of connecting a cover member to the surface of the insulating substrate on which the fuse element is mounted so as to cover the surface of the substrate; A protrusion for holding the flux at a predetermined position is erected on the cover member so as to face the intermediate electrode. The intermediate electrode has a length longer than a width of the fuse element in a direction perpendicular to a current-carrying direction of the fuse element, and at least one of the ends of the intermediate electrode extends out from the fuse element. The protrusion is provided at a position facing a position of the intermediate electrode where the fuse element is mounted and at a position facing the end of the intermediate electrode where the fuse element is not mounted, and holds the flux on the fuse element and the end.

8. A method for manufacturing a protection device, comprising: A process for forming a connected body, wherein: The connecting body comprises an insulating substrate, an intermediate electrode provided on the surface side of the insulating substrate, a heating element provided on the back side opposite to the surface of the insulating substrate, and an insulating layer covering the heating element, wherein a fuse element is mounted on the intermediate electrode; A step of applying flux on the fuse element and the intermediate electrode via a mask having an opening corresponding to a coating area; as well as a step of connecting a cover member to the surface of the insulating substrate on which the fuse element is mounted so as to cover the surface of the substrate; A protrusion for holding the flux at a predetermined position is erected on the cover member so as to face the intermediate electrode. The intermediate electrode has a length longer than a width of the fuse element in a direction perpendicular to a current-carrying direction of the fuse element, and at least one of the ends of the intermediate electrode extends out from the fuse element. The protrusion is provided at a position facing a position of the intermediate electrode where the fuse element is mounted and at a position facing the end of the intermediate electrode where the fuse element is not mounted, and holds the flux on the fuse element and the end.

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