Protective element, and battery pack

Abstract

To provide a protective element capable of improving insulation properties after melting of a fuse element, and a battery pack using the same.SOLUTION: A protective element 1 comprises: an insulation substrate 2; a first electrode 11 and a second electrode 12; an intermediate electrode 13 disposed between the first electrode 11 and the second electrode 12; a fuse element 3 which is disposed on surfaces of the first electrode 11, the second electrode 12 and the intermediate electrode 13 and electrically connects the first electrode 11 with the second electrode 12 and the second electrode 12 with the intermediate electrode 13; and a deposition prevention section 5 which is provided between the first electrode 11 and the intermediate electrode 13 and / or between the second electrode 12 and the intermediate electrode 13 and suppresses deposition of molten scattered materials of the fuse element 3.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present technology relates to a protection element that cuts off a current path, and a battery pack using the same. [Background technology]

[0002] Most secondary batteries that can be recharged and used repeatedly are provided to users as battery packs. In particular, lithium-ion secondary batteries, which have a high weight energy density, generally have several protection circuits built into the battery pack, such as overcharge protection and overdischarge protection, and have the function of cutting off the output of the battery pack in certain cases, in order to ensure the safety of users and electronic devices.

[0003] In many electronic devices using lithium-ion secondary batteries, the battery pack is protected from overcharging or overdischarging by turning on / off the output using a FET switch built into the battery pack. However, even if the FET switch is short-circuited and broken for some reason, if a lightning surge or the like is applied and a momentary large current flows, or if the output voltage drops abnormally due to the life of the battery cell or, conversely, an excessive abnormal voltage is output, the battery pack and electronic devices must be protected from accidents such as fire. Therefore, in order to safely cut off the output of the battery cell in any of these possible abnormal conditions, a protection element consisting of a fuse element that has the function of cutting off the current path by an external signal is used.

[0004] A protective element for such a protection circuit for a lithium ion secondary battery or the like has a structure in which a heating element is provided inside the protective element, and a fusible conductor on a current path is melted by heat generated by the heating element.

[0005] The applications of lithium-ion secondary batteries have expanded in recent years, and they have begun to be adopted for larger current applications, such as power tools such as power drivers, transportation equipment such as hybrid cars, electric cars, and power-assisted bicycles, drones, etc. In these applications, particularly at startup, a large current of several tens of A to more than 100 A may flow. There is a demand for a protection element that can handle such a large current capacity.

[0006] In order to realize a protective element that can handle such a large current, a protective element has been proposed in which a fusible conductor with an increased cross-sectional area is used and an insulating substrate on which a heating element is formed is connected to the surface of the fusible conductor.

[0007] Fig. 18 is a diagram showing a configuration example of a conventional protection element, (A) being a plan view and (B) being a circuit diagram. Fig. 19 is a diagram showing a state in which a fuse element is melted in the conventional protection element shown in Fig. 18, (A) being a plan view and (B) being a circuit diagram. The protection element 100 shown in Fig. 18 includes an insulating substrate 103, a first electrode 101 and a second electrode 102 provided on the insulating substrate 103, an intermediate electrode 104 disposed between the first electrode 101 and the second electrode 102, and a fuse element 105 disposed from the first electrode 101 to the second electrode 102 and electrically connecting between the first electrode 101 and the intermediate electrode 104 and between the second electrode 102 and the intermediate electrode 104.

[0008] On the surface of the insulating substrate 103, there are formed a heating element 106, an insulating layer 107 covering the heating element 106, a heating element power supply electrode 108 serving as a power supply terminal to the heating element 106, and a heating element electrode 109 connected to the intermediate electrode 104. One end of the heating element 106 is connected to the heating element power supply electrode 108, and the other end is connected to the heating element electrode 109. Thus, the heating element 106 is connected to the fuse element 105 via the heating element electrode 109 and the intermediate electrode 104.

[0009] The fuse element 105 is connected to the first and second electrodes 101 and 102, which are connected to an external circuit, and the intermediate electrode 104, by a bonding material such as a connection solder.

[0010] When an abnormality such as overcharging or overcurrent of the lithium ion battery is detected, electricity is applied from an external power source to the heating element 106, which generates heat. The fuse element 105 is melted by the heat of the heating element 106, and the molten conductor is condensed on the intermediate electrode 104 and the first and second electrodes 101, 102, thereby cutting off the electrical continuity between the first and second electrodes 101, 102.

[0011] In addition, the protection element 100 has a maximum current and a rated voltage set according to the electronic device in which it is used, and when power exceeding the set value is applied, the fuse element 105 generates heat (Joule heat) due to the passage of electricity and melts, thereby cutting off the electrical continuity between the first and second electrodes 101 and 102. Since the fuse element 105 exists alone between the first electrode 101 and the intermediate electrode 104 and between the second electrode 102 and the intermediate electrode 104, the resistance value is relatively high and a large amount of heat is generated when electricity is passed through the fuse element 105. Therefore, when an overcurrent flows, the melting point of the fuse element 105 is exceeded between the first electrode 101 and the intermediate electrode 104 and between the second electrode 102 and the intermediate electrode 104, causing the fuse element 105 to melt.

[0012] As shown in FIG. 19, when self-heating caused by an overcurrent is cut off, either the gap between the first electrode 101 and the intermediate electrode 104 or the gap between the second electrode 102 and the intermediate electrode 104 may melt, or both may melt. [Prior art documents] [Patent documents]

[0013] [Patent Document 1] Patent No. 3067011 Summary of the Invention [Problem to be solved by the invention]

[0014] As mentioned above, lithium-ion batteries and other batteries are being expanded from their use in mobile devices to applications such as EVs and storage batteries, and as a result, there is a demand for protection elements that can handle higher rated voltages and larger current capacities.

[0015] Here, when the current is interrupted, the product of the overcurrent and the voltage is applied as power to the melting point of the fuse element. Therefore, when the rated voltage of the current is increased, the power (energy) applied to the melting point of the fuse element also increases, and the fuse element continues to rise in temperature in a melted state due to self-heating, and further reaches its boiling point and vaporizes explosively. FIG. 20(A) is a plan view that shows a state in which the molten conductor 105a of the fuse element 105 is explosively vaporized at the melting point of the fuse element 105. The vapor of the molten conductor 105a of the fuse element 105 that has vaporized explosively scatters, and black soot-like material 111 adheres to the insulating substrate 103 and the fuse element 105. FIG. 20(B) is a plan view that shows a state in which the vapor of the molten conductor of the fuse element 105 is scattered and adheres to the insulating substrate 103 and the unmelted fuse element 105 as soot-like material 111. This soot-like material 111 becomes conductive, and a conductive path 110 is formed between the blown fuse elements, which may result in a decrease in insulation resistance.

[0016] In view of the above, an object of the present technology is to provide a protection element capable of improving insulation after a fuse element has blown, and a battery pack using the same. [Means for solving the problem]

[0017] In order to solve the above-mentioned problems, the protective element of the present technology includes an insulating substrate, a first electrode and a second electrode provided on the insulating substrate, an intermediate electrode arranged between the first electrode and the second electrode, a fuse element arranged on surfaces of the first electrode, the second electrode, and the intermediate electrode and electrically connecting between the first electrode and the intermediate electrode and between the second electrode and the intermediate electrode, and an adhesion prevention portion provided between the first electrode and the intermediate electrode and / or between the second electrode and the intermediate electrode, and suppressing adhesion of molten debris from the fuse element.

[0018] In addition, a battery pack according to the present technology includes one or more battery cells and a protection element connected to a charge / discharge path of the battery cell and blocking the charge / discharge path, the protection element being the protection element described above. Effect of the Invention

[0019] When current is interrupted, the temperature of the protective element continues to rise while the fuse element is in a molten state due to self-heating, and the molten conductor of the fuse element reaches its boiling point and vaporizes explosively, scattering the vapor of the molten conductor, causing a black soot-like substance to adhere to the surface of the insulating substrate, etc. However, according to the present technology, the soot-like substance only adheres in an island-like manner on the adhesion prevention portion. In other words, the soot-like substance is not continuous in the region between the first electrode and the intermediate electrode and / or the region between the second electrode and the intermediate electrode, and it is possible to prevent the formation of a conductive path. Therefore, the protective element can maintain a high insulation resistance between the first and second electrodes after current is interrupted. [Brief description of the drawings]

[0020] [Figure 1] FIG. 1 shows a protection element to which the present technology is applied, where (A) is a plan view showing the cap member omitted, (B) is an A-A' cross-sectional view of (A), and (C) is a B-B' cross-sectional view of (A). [Diagram 2]2A and 2B are diagrams showing a state in which a fuse element in a protection element melts due to current interruption, cutting off electrical continuity between the first and second electrodes, in which (A) is a plan view showing the state without the cap member, and (B) is a cross-sectional view taken along the line B-B' of (A). [Diagram 3] FIG. 3 is a plan view of the protective element, with the cap member, fuse element, and adhesion prevention portion omitted. [Figure 4] FIG. 4 is a plan view showing a configuration in which an adhesion prevention portion is provided in at least the entire region between the first electrode and the intermediate electrode and / or the entire region between the second electrode and the intermediate electrode. [Diagram 5] FIG. 5(A) is a plan view showing a configuration in which an adhesion prevention portion is provided in contact with an intermediate electrode, and FIG. 5(B) is a plan view showing a configuration in which an adhesion prevention portion is provided overlapping the intermediate electrode. [Figure 6] Figure 6(A) is a plan view showing a configuration in which an adhesion prevention portion is provided in contact with a first electrode and / or a second electrode, and Figure 6(B) is a plan view showing a configuration in which an adhesion prevention portion is provided overlapping the first electrode and / or the second electrode. [Figure 7] FIG. 7 is a plan view showing a configuration in which the adhesion prevention portion is formed without any gaps in the region between the first electrode and the intermediate electrode and / or the region between the second electrode and the intermediate electrode. [Figure 8] Figure 8 is a cross-sectional view showing an example of a manufacturing process for the adhesion prevention part, where Figure 8(A) shows the process of applying the resin material that constitutes the adhesion prevention part, Figure 8(B) shows the state after the resin material has been applied, and Figure 8(C) shows the state after the fuse element has been mounted and flux has been applied. [Figure 9] FIG. 9 is a cross-sectional view showing an example of a fuse element. [Figure 10] FIG. 10 is a cross-sectional view showing a state in which the fuse element has been blown, where (A) is a plan view showing the fuse element without the cap member, and (B) is a cross-sectional view taken along the line BB' of (A). [Figure 11] FIG. 11 is a circuit diagram showing an example of the configuration of a battery pack. [Figure 12] FIG. 12 is a circuit diagram of a protection element. [Figure 13] Figure 13 is a diagram showing a protective element according to a modified example, where (A) is a plan view showing the cap member omitted, (B) is an A-A' cross-sectional view shown in (A), (C) is a B-B' cross-sectional view shown in (A), and (D) is a bottom view. [Figure 14] FIG. 14 is a plan view showing a state in which the metal mask is placed. [Figure 15] FIG. 15 is a plan view showing a state in which two fuse elements are mounted side by side between the first electrode and the intermediate electrode, and between the second electrode and the intermediate electrode. [Figure 16] FIG. 16 is a graph showing the current-time characteristics when a power of 240 A-100 V is applied to an example sample provided with an adhesion prevention portion and the current is interrupted, where (A) shows the period from before the application of power until after the current is interrupted, and (B) shows an enlarged view of the area around the time of current interruption. [Figure 17] FIG. 17 is a graph showing the current-time characteristics when a power of 240 A-100 V was applied to a comparative sample not provided with an adhesion prevention portion and the current was interrupted, where (A) shows the period from before the application of power to after the current was interrupted, and (B) shows an enlarged view of the area around the time of current interruption. [Figure 18] FIG. 18 shows an example of a configuration of a conventional protection element, where (A) is a plan view and (B) is a circuit diagram. [Figure 19] 19A and 19B are diagrams showing a state in which the fuse element in the conventional protection element shown in FIG. 18 has been blown, where (A) is a plan view and (B) is a circuit diagram. [Figure 20] FIG. 20(A) is a plan view showing the state in which the molten conductor of the fuse element is explosively vaporized at the melting site of the fuse element, and FIG. 20(B) is a plan view showing the state in which the vapor of the molten conductor of the fuse element scatters and adheres to the insulating substrate and unmelted fuse element as a soot-like substance. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0021] Hereinafter, a protective element and a battery pack to which the present technology is applied will be described in detail with reference to the drawings. The present technology is not limited to the following embodiments, and various modifications are possible within the scope of the present technology. The drawings are schematic, and the ratios of the dimensions may differ from the actual ones. The specific dimensions should be determined with reference to the following description. The drawings also include parts in which the dimensional relationships and ratios differ from one another.

[0022] 1 is a diagram showing a protection element 1 to which the present technology is applied, where (A) is a plan view showing the cap member omitted, (B) is an A-A' cross-sectional view of (A), and (C) is a B-B' cross-sectional view of (A). The protection element 1 to which the present technology is applied includes an insulating substrate 2, a first electrode 11 and a second electrode 12 provided on the insulating substrate 2, an intermediate electrode 13 arranged between the first electrode 11 and the second electrode 12, a fuse element 3 arranged on the surfaces of the first electrode 11, the second electrode 12, and the intermediate electrode 13 to electrically connect between the first electrode 11 and the intermediate electrode 13 and between the second electrode 12 and the intermediate electrode 13, and an adhesion prevention part 5 provided between the first electrode 11 and the intermediate electrode 13 and / or between the second electrode 12 and the intermediate electrode 13 to suppress adhesion of molten spatter of the fuse element 3.

[0023] The protective element 1 has a maximum current and a rated voltage set according to the electronic device in which it is used, and when power exceeding the set value is applied, the fuse element 3 generates heat (Joule heat) due to current flow and melts, thereby cutting off the electrical continuity between the first and second electrodes 11, 12. Figure 2 shows a state in which the fuse element 3 melts due to current interruption in the protective element 1, cutting off the electrical continuity between the first and second electrodes 11, 12, where (A) is a plan view without the cap member, and (B) is a cross-sectional view taken along line B-B' of (A).

[0024] When the current is interrupted, the temperature of the protective element 1 continues to rise while the fuse element 3 is melted due to self-heating, and the molten conductor 3a of the fuse element 3 reaches its boiling point and vaporizes explosively, the vapor of the molten conductor 3a scatters, and the black soot-like substance 14 adheres to the surface 2a of the insulating substrate 2, etc. However, on the adhesion prevention portion 5, the soot-like substance 14 only adheres in an island-like manner. That is, the soot-like substance 14 is not continuous in the region 10a between the first electrode 11 and the intermediate electrode 13 and / or the region 10b between the second electrode 12 and the intermediate electrode 13, and it is possible to prevent the formation of a conductive path. Therefore, the protective element 1 can maintain a high insulation resistance between the first and second electrodes 11, 12 after the current is interrupted.

[0025] Below, a detailed description is given of each component of the protection element 1. The protection element 1 shown in Fig. 1 includes a heating element 6 and an insulating layer 7 covering the heating element 6 on a surface 2a of an insulating substrate 2 on which the fuse element 3 is provided, and in addition to being cut off by an overcurrent, the fuse element 3 is also melted by heat generated by the heating element 6, cutting off electrical continuity between the first and second electrodes 11, 12.

[0026] [Insulating substrate] The insulating substrate 2 is formed of an insulating material such as alumina, glass ceramics, mullite, or zirconia. Alternatively, the insulating substrate 2 may be made of a material used for printed wiring boards, such as a glass epoxy board or a phenol board. 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.

[0027] [First and second electrodes] A first electrode 11 and a second electrode 12 are formed on both opposing ends of the surface 2a of the insulating substrate 2. The first electrode 11 and the second electrode 12 are each formed of a conductive pattern of Ag, Cu, an alloy thereof, or the like. The first electrode 11 and the second electrode 12 can be formed, for example, by printing an Ag paste in a predetermined pattern by screen printing, and then firing the resulting pattern at a predetermined temperature.

[0028] The first electrode 11 is continuous from the front surface 2a of the insulating substrate 2 to a first external connection electrode 15 formed on the back surface 2b via a castellation. The second electrode 12 is continuous from the front surface 2a of the insulating substrate 2 to a second external connection electrode 16 formed on the back surface 2b via a castellation. In the surface mount type protection element 1, when the protection element 1 is mounted on an external circuit board, the first and second external connection electrodes 15, 16 are connected to connection electrodes provided on the external circuit board, and the fuse element 3 is incorporated into a part of the current path formed on the external circuit board.

[0029] The first and second electrodes 11, 12 are electrically connected via the fuse element 3 by mounting the fuse element 3 via various tin-based solder pastes or other conductive connection materials. The first and second electrodes 11, 12 are disconnected when the heating element 6 generates heat as current flows and the fuse element 3 melts, or when a large current exceeding the rated current flows through the protection element 1 and the fuse element 3 melts due to self-heating (Joule heat) as shown in Fig. 2.

[0030] [Heater] A protective element to which the present technology is applied preferably includes, on an insulating substrate 2, a heating element 6 that melts the fuse element 3 by generating heat, and an insulating layer 7 that covers the heating element 6. In the protective element 1 shown in Figs. 1 and 2, the heating element 6 and the insulating layer 7 are provided on a surface 2a of the insulating substrate 2.

[0031] The heating element 6 is a conductive member that generates heat when a current is applied and is made of, for example, nichrome, W, Mo, Ru, or a material containing these. The heating element 6 can be formed by mixing a powder of these alloys, compositions, or compounds with a resin binder or the like, forming a paste on the insulating substrate 2 using a screen printing technique, and firing the paste. As an example, the heating element 6 can be formed by adjusting a mixed paste of a ruthenium oxide paste, silver, and glass paste according to a predetermined voltage, forming a film of a predetermined area at a predetermined position on the surface 2a of the insulating substrate 2, and then firing the film under appropriate conditions. The shape of the heating element 6 can be designed as appropriate, but it is preferable to make it approximately rectangular according to the shape of the insulating substrate 2 as shown in FIG. 1 in order to maximize the heating area.

[0032] 3 is a plan view of the protective element 1, with the cap member 24, the fuse element 3, and the adhesion prevention part 5 omitted. One end 6a of the heating element 6 is connected to a first lead electrode 17, and the other end 6b is connected to a second lead electrode 18. The first lead electrode 17 is led out from a heating element power supply electrode 8 formed on one side edge of the surface 2a of the insulating substrate 2. The second lead electrode 18 is led out from a heating element electrode 9 formed on the other side edge of the surface 2a of the insulating substrate 2. The first lead electrode 17 is led out from the heating element power supply electrode 8 along one end 6a of the heating element 6, and in the protective element 1 shown in FIG. 1, it extends along one side edge of the heating element 6 formed in a substantially rectangular shape, and one side edge of the heating element 6 is overlapped. Similarly, the second extraction electrode 18 is extracted from the heating element electrode 9 along the other end 6b of the heating element 6, and in the protection element 1 shown in Figure 1, it extends along the other side edge of the heating element 6 which is formed in a substantially rectangular shape and overlaps the other side edge of the heating element 6.

[0033] [Insulation layer] Moreover, the heating element 6, the first extraction electrode 17 and the second extraction electrode 18 are covered with an insulating layer 7. Moreover, on the insulating layer 7, an intermediate electrode 13 is formed.

[0034] The insulating layer 7 serves to protect and insulate the heating element 6. The insulating layer 7 is formed to be thin, for example, 10 to 40 μm, in order to efficiently transfer heat from the heating element 6 to the intermediate electrode 13 and the fuse element 3. The insulating layer 7 can be formed, for example, by applying and baking a glass-based paste.

[0035] The heating element power supply electrode 8 and the heating element electrode 9 are formed on opposing side edges of the insulating substrate 2 different from the side edges on which the first and second electrodes 11, 12 are provided. The heating element power supply electrode 8 is an electrode that serves as a power supply terminal to the heating element 6, and is connected to one end 6a of the heating element 6 via a first extraction electrode 17, and is continuous with a third external connection electrode 19 formed on the rear surface 2b of the insulating substrate 2 via a castellation (see FIG. 1(B)). The heating element electrode 9 is connected to the other end 6b of the heating element 6 via a second extraction electrode 18, and is also connected to the intermediate electrode 13.

[0036] The heating element power supply electrode 8, the heating element electrode 9, the first and second lead electrodes 17, 18, and the intermediate electrode 13 can be formed by printing and firing a conductive paste of Ag, Cu, or the like, in the same manner as the first and second electrodes 11, 12. Furthermore, by making each of these electrodes formed on the surface 2a of the insulating substrate 2 out of the same material, they can be formed in one or more printing and firing steps.

[0037] The heating element power supply electrode 8 may be provided with a restricting wall (not shown) for preventing the connection solder provided on the electrode of the external circuit board connected to the third external connection electrode 19 from melting during reflow mounting or the like, creeping up onto the heating element power supply electrode 8 through castellation, and spreading over the heating element power supply electrode 8. The first and second electrodes 11 and 12 may also be provided with a restricting wall. The restricting wall can be formed using an insulating material that is not wettable by solder, such as glass, solder resist, or insulating adhesive, and can be formed on the heating element power supply electrode 8 or the first and second electrodes 11 and 12 by printing or the like. By providing the restricting wall, the molten connection solder is prevented from spreading over the heating element power supply electrode 8 or the first and second electrodes 11 and 12, and the connectivity between the protection element 1 and the external circuit board can be maintained.

[0038] [Intermediate electrode] The intermediate electrode 13 is an electrode provided from the heating element electrode 9 onto the insulating layer 7. The intermediate electrode 13 is formed of a conductive pattern of Ag, Cu, or the like. One end of the intermediate electrode 13 is connected to the other end 6b of the heating element 6 via the heating element electrode 9 and the second extraction electrode 18. The other end of the intermediate electrode 13 extends onto the insulating layer 7 in the region between the first electrode 11 and the second electrode 12, and is superimposed on the heating element 6 via the insulating layer 7. The intermediate electrode 13 is connected to the fuse element 3 via a bonding material such as a connection solder.

[0039] The fuse element 3 is mounted between the first and second electrodes 11, 12, and melts due to heat generated by energization of the heating element 6 or self-heating (Joule heat) when a current exceeding the rated current is passed through it, thereby cutting off the current path between the first electrode 11 and the second electrode 12. Flux 4 is applied to the fuse element 3 in order to prevent oxidation, improve wettability, and achieve rapid melting. As shown in FIG. 1, the protective element 1 may be a single fuse element 3 mounted between the first and second electrodes 11, 12, or may have fuse elements 3 mounted between the first electrode 11 and the intermediate electrode 13 and between the second electrode 12 and the intermediate electrode 13. The configuration of the fuse element 3 will be described in detail later.

[0040] It is preferable that the surfaces of the first and second electrodes 11, 12 and the intermediate electrode 13 are coated with a film such as Ni / Au plating, Ni / Pd plating, Ni / Pd / Au plating, etc., by a known method such as plating. This prevents the first and second electrodes 11, 12 and the intermediate electrode 13 of the protective element 1 from being oxidized, and prevents fluctuations in the rating due to an increase in the conductive resistance. In addition, when the protective element 1 is reflow mounted, it is possible to prevent the first and second electrodes 11, 12 and the intermediate electrode 13 from being corroded (solder eaten) by melting the connection solder that connects the fuse element 3.

[0041] [Adhesion prevention part] An adhesion prevention portion 5 that suppresses adhesion of molten spatter from the fuse element 3 is provided in the region 10a between the first electrode 11 and the intermediate electrode 13 and / or the region 10b between the second electrode 12 and the intermediate electrode 13. The adhesion prevention portion 5 is formed of a resin coating layer such as a cured product of an epoxy resin, a fluorine-based resin, a silicone resin, or a resin combination thereof.

[0042] 2, when the fuse element 3 melts due to self-heating and continues to rise in temperature, and then reaches its boiling point and vaporizes explosively, causing the molten conductor 3a of the fuse element 3 to scatter. Even if this happens, the soot-like material 14 will only adhere to the adhesion prevention part 5 in an island-like manner. That is, the soot-like material 14 will not be continuous in the region 10a between the first electrode 11 and the intermediate electrode 13 and / or the region 10b between the second electrode 12 and the intermediate electrode 13, preventing the formation of a conductive path. Therefore, the protective element 1 can maintain a high insulation resistance after current interruption.

[0043] In order to block the current path between the first electrode 11 and the second electrode 12, it is sufficient that the adhesion prevention part 5 is provided in the region 10a between the first electrode 11 and the intermediate electrode 13, or in the region 10b between the second electrode 12 and the intermediate electrode 13. However, in order to ensure a higher insulation resistance after current blocking, it is preferable that the adhesion prevention part 5 be provided in the region 10a between the first electrode 11 and the intermediate electrode 13 and in the region 10b between the second electrode 12 and the intermediate electrode 13.

[0044] As shown in FIG. 4, the adhesion prevention part 5 is preferably provided in at least the entire region 10a between the first electrode 11 and the intermediate electrode 13 and / or the entire region 10b between the second electrode 12 and the intermediate electrode 13. This can prevent the formation of a conductive path due to the continuous adhesion of the soot-like material 14 between the first electrode 11 and the intermediate electrode 13 or between the second electrode 12 and the intermediate electrode 13. Note that, as shown in FIG. 1, the adhesion prevention part 5 may be formed continuously across the opposing side edges of the insulating substrate 2 on which the heating element power supply electrode 8 and the heating element electrode 9 are provided. This can prevent the formation of a conductive path due to the continuous adhesion of the soot-like material 14 between the heating element power supply electrode 8 and the heating element electrode 9 and the first electrode 11 and the second electrode.

[0045] As shown in FIG. 5, the adhesion prevention part 5 may be provided in contact with the intermediate electrode 13 (FIG. 5(A)), or may be provided overlapping the intermediate electrode 13 (FIG. 5(B)).

[0046] As shown in FIG. 6, the adhesion prevention part 5 may be provided in contact with the first electrode 11 and / or the second electrode 12 (FIG. 6(A)), or may be provided overlapping the first electrode 11 and / or the second electrode 12 (FIG. 6(B)).

[0047] Furthermore, as shown in FIG. 7, the adhesion prevention portion 5 may be formed without any gaps in the region 10a between the first electrode 11 and the intermediate electrode 13 and / or the region 10b between the second electrode 12 and the intermediate electrode 13.

[0048] The adhesion prevention part 5 is preferably formed to a thickness that does not contact the fuse element 3. If the adhesion prevention part 5 is formed to a thickness that contacts the fuse element 3, for example, when the fuse element 3 is mounted on the first and second electrodes 11, 12 and the intermediate electrode 13 by reflow, the fuse element 3 may be lifted by the adhesion prevention part 5 and move from a predetermined mounting position. This may affect the internal resistance, such as reducing the contact area between the fuse element 3 and the first and second electrodes 11, 12 or making the contact area uneven. Furthermore, if the movement of the fuse element 3 becomes large, in the worst case, there is a risk that the fuse element 3 may come off the first electrode 11 or the second electrode 12.

[0049] When attempting to mount the fuse element 3 between the first electrode 11 and the intermediate electrode 13, and between the second electrode 12 and the intermediate electrode 13 (see Figure 15), self-alignment between the first and second electrodes 11, 12 does not work, and the fuse element 3 is prone to movement due to contact with the anti-adhesion portion 5, and in the worst case scenario, there is a risk that the fuse element 3 will come off the intermediate electrode 13.

[0050] Therefore, it is preferable that the adhesion prevention part 5 is formed to a thickness that does not contact the fuse element 3. For example, by forming the adhesion prevention part 5 to a thickness that makes the upper surface of the adhesion prevention part 5 lower than the upper surfaces of the first and second electrodes 11 and 12 and the intermediate electrode 13, the fuse element 3 and the adhesion prevention part 5 are separated, and movement of the fuse element 3 during reflow mounting, etc. can be prevented.

[0051] It is desirable that the adhesion prevention portion 5 and the fuse element 3 are spaced apart over the entire opposing surfaces, but partial contact is not a problem as long as it does not result in serious movement of the fuse element 3 that would cause a significant fluctuation in internal resistance or loss of connection with the intermediate electrode 13.

[0052] [Step for forming adhesion prevention part] The adhesion prevention portion 5 can be formed by applying and curing a resin material 5a such as epoxy resin to a predetermined area through a mask 22 having openings 21 corresponding to the formation area, and providing a resin coating layer in the areas 10a and 10b (see FIG. 8). In this application method, a mask 22 such as a metal mask or a screen mask having openings 21 corresponding to the formation area of ​​the adhesion prevention portion 5 is prepared, and the mask 22 is placed around the formation area of ​​the adhesion prevention portion 5, and the resin material 5a is pressed with a squeegee 23. This allows the resin material 5a to be printed in the opening areas of the mask.

[0053] Alternatively, the adhesion prevention portion 5 may be formed by applying the resin material 5a to a position corresponding to the formation region using a dispenser, a spray, or the like, and then curing the applied resin material 5a.

[0054] The curing process of the resin material 5a constituting the adhesion prevention part 5 may be appropriately set according to the curing system of the resin material 5a. The curing method of the resin material 5a may also be appropriately set according to the material, and may be, for example, heated for a predetermined time in a reflow furnace, heated and dried by a dryer, irradiated with curing light, or left to stand at room temperature for a predetermined time to be cured.

[0055] Alternatively, the adhesion prevention portion 5 may be formed by forming the resin material 5a into a film on the surface of a release film such as PET, attaching the material surface of the material film to a position corresponding to the formation area, and transferring and hardening the resin material 5a to the formation area by heating and pressing from the release film side using a heating bonder or the like.

[0056] [Cap material] The surface 2a of the insulating substrate 2 on which the fuse element 3 is mounted is covered with a cap member 24. The cap member 24 protects the inside of the protection element 1 and prevents the molten material generated when the fuse element 3 melts from scattering.

[0057] The cap member 24 may be made of insulating materials such as various engineering plastics and ceramics. The cap member 24 is provided on the surface 2a of the insulating substrate 2 and fixed with an adhesive. The cap member 24 has an internal space sufficient to allow the molten conductor 3a to expand spherically when the fuse element 3 melts and to aggregate on the intermediate electrode 13 and the first and second electrodes 11 and 12.

[0058] [Protection element manufacturing process] Next, a description will be given of a manufacturing process of the protection element 1. The manufacturing process of the protection element 1 includes a step of forming the heating element 6, the first electrode 11, the second electrode 12, the heating element power supply electrode 8, the heating element electrode 9, the first lead electrode 17, the second lead electrode 18, the insulating layer 7, and the intermediate electrode 13 on the insulating substrate 2, a step of forming an adhesion prevention part 5 between the intermediate electrode 13 and the first electrode 11 and / or the second electrode 12, a step of connecting the fuse element 3 across the first electrode 11, the intermediate electrode 13, and the second electrode 12, and a step of connecting a cap member 24 to the surface 2a of the insulating substrate 2 on which the fuse element 3 is mounted, to cover the substrate surface.

[0059] As described above, the first and second electrodes 11, 12, the heating element power supply electrode 8, the heating element electrode 9, and the first and second extraction electrodes 17, 18 are formed on the surface 2a of the insulating substrate 2 by printing and firing a conductive paste such as Ag or Cu using a screen printing technique or the like.

[0060] The heating element 6 is made of nichrome, W, Mo, Ru, or the like, or a material containing these, and can be formed by mixing a powder of these alloys, compositions, or compounds with a resin binder or the like to form a paste, forming a pattern on the insulating substrate 2 using a screen printing technique or the like, and firing the paste. The insulating layer 7 is formed on the heating element 6 and the first and second extraction electrodes 17, 18 by applying a glass-based paste or the like using a screen printing technique or the like, and firing the paste.

[0061] Furthermore, an intermediate electrode 13 is formed from the heating electrode 9 onto the insulating layer 7 by printing and baking a conductive paste of Ag, Cu, or the like using a screen printing technique or the like.

[0062] Figure 8 is a cross-sectional view showing an example of a manufacturing process for adhesion prevention part 5, where Figure 8(A) shows the process of applying resin material 5a which constitutes adhesion prevention part 5, Figure 8(B) shows the state after resin material 5a has been applied, and Figure 8(C) shows the state after fuse element 3 has been mounted and flux 4 has been applied.

[0063] As shown in Fig. 8, the resin material 5a constituting the adhesion prevention part 5 is applied onto the surface 2a of the insulating substrate 2 through a mask 22 (metal mask, screen mask, etc.) having openings 21 corresponding to the application area. In this application process, as shown in Fig. 8(A), in the screen printing method, a mask 22 having openings 21 corresponding to the printed part of the resin material 5a is placed around the printed part, and a squeegee 23 slides on the surface of the mask 22, so that the resin material 5a can be applied at a position and in an area corresponding to the openings 21 (Fig. 8(B)). After printing the resin material 5a, a curing process corresponding to the curing system is performed, and the adhesion prevention part 5 consisting of a resin coat layer is formed.

[0064] Next, a conductive connecting material such as connecting solder is printed on the first and second electrodes 11, 12 and the intermediate electrode 13, the fuse element 3 is mounted, and then a reflow process is performed. As a result, the fuse element 3 is connected (FIG. 8(C)). Thereafter, a cap member 24 is connected to the surface 2a of the insulating substrate 2 on which the fuse element 3 is mounted, to cover the substrate surface, and the protection element 1 is obtained.

[0065] [Fuse element] Next, a detailed configuration of the fuse element 3 will be described. The fuse element 3 is mounted between the first and second electrodes 11, 12, and melts down due to heat generated by energization of the heating element 6 or self-heating (Joule heat) when a current exceeding the rated current is passed through it, thereby cutting off the current path between the first electrode 11 and the second electrode 12.

[0066] The fuse element 3 may be made of any conductive material that melts when heat is generated by the passage of current through the heating element 6 or when an overcurrent occurs. For example, SnAgCu-based Pb-free solder, BiPbSn alloy, BiPb alloy, BiSn alloy, SnPb alloy, PbIn alloy, ZnAl alloy, InSn alloy, PbAgSn alloy, etc. can be used.

[0067] The fuse element 3 may also be a structure containing a high melting point metal and a low melting point metal. For example, as shown in Fig. 9, the fuse element 3 is a laminated structure consisting of an inner layer and an outer layer, and has a low melting point metal layer 26 as the inner layer and a high melting point metal layer 27 as the outer layer laminated on the low melting point metal layer 26. The fuse element 3 is connected onto the first and second electrodes 11, 12 and the intermediate electrode 13 via a conductive connection material such as a connection solder.

[0068] The low melting point metal layer 26 is preferably a metal mainly composed of solder or Sn, and is a material generally called "Pb-free solder". The melting point of the low melting point metal layer 26 does not necessarily need to be higher than the temperature of the reflow furnace, and may melt at about 200°C. The high melting point metal layer 27 is a metal layer laminated on the surface of the low melting point metal layer 26, and is, for example, Ag or Cu or a metal mainly composed of either of them, and has a high melting point that does not melt even when the first and second electrodes 11, 12 and the intermediate electrode 13 are connected to the fuse element 3 or the protection element 1 is mounted on an external circuit board by reflow.

[0069] 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 be formed using other well-known lamination techniques or film formation techniques. The fuse element 3 may have a structure in which the entire surface of the low melting point metal layer 26 is covered with the high melting point metal layer 27, or may have a structure in which the low melting point metal layer 26 is covered except for a pair of opposing side surfaces. The fuse element 3 may also have a coating structure in which the high melting point metal layer 27 is an inner layer and the low melting point metal layer 26 is an outer layer. Furthermore, the fuse element 3 can be formed in various configurations, such as a two-layer structure in which the lower layer is the low melting point metal layer 26 and the upper layer is the high melting point metal layer 27, a multilayer structure in which low melting point metal layers and high melting point metal layers are alternately laminated, or a structure in which an opening is provided in a part of the outer layer to expose a part of the inner layer.

[0070] By providing the coating structure or laminated structure of the low melting point metal layer 26 and the high melting point metal layer 27, the fuse element 3 can maintain its shape and does not melt even when the reflow temperature exceeds the melting temperature of the low melting point metal layer 26. Therefore, the first and second electrodes 11, 12 and the intermediate electrode 13 can be connected to the fuse element 3 and the protective element 1 can be mounted on an external circuit board efficiently by reflow, and it is possible to prevent fluctuations in the fusing characteristics, such as not melting at a predetermined temperature or melting at a temperature lower than the predetermined temperature, due to a locally high or low resistance value caused by deformation of the fuse element 3 even by reflow.

[0071] In addition, the fuse element 3 will not melt even due to self-heating while a predetermined rated current flows. When a current higher than the rated current flows, the fuse element melts due to self-heating, and cuts off the current path between the first and second electrodes 11 and 12. At this time, as described above, the adhesion prevention part 5 that suppresses adhesion of the molten spatter of the fuse element 3 is provided in the region 10a between the first electrode 11 and the intermediate electrode 13 and / or the region 10b between the second electrode 12 and the intermediate electrode 13. Therefore, even if the vapor of the molten conductor 3a of the fuse element 3 is scattered, the soot-like material 14 does not continue on the adhesion prevention part 5, and it is possible to prevent the formation of a conductive path. Therefore, the protective element 1 can maintain a high insulation resistance after the current is interrupted.

[0072] Furthermore, when a current is passed through the heating element 6, it melts and cuts off the current path between the first and second electrodes 11, 12. The adhesion prevention part 5 also has the property of repelling the molten conductor 3a of the fuse element 3, and since the molten conductor 3a aggregates on the intermediate electrode 13 and the first and second electrodes 11, 12, it is possible to prevent the molten conductor 3a from continuing between the intermediate electrode 13 and the first and second electrodes 11, 12. Therefore, the protective element 1 can maintain a high insulation resistance after current interruption.

[0073] In addition, when the fuse element 3 generates heat from the heating element 6 or self-heats due to an overcurrent, the low melting point metal layer 26 that melts first corrodes (solder eats) the high melting point metal layer 27, causing the high melting point metal layer 27 to melt at a temperature lower than the melting temperature. Therefore, the fuse element 3 can be blown in a short time by utilizing the corrosion of the high melting point metal layer 27 by the low melting point metal layer 26. In addition, the molten conductor 3a of the fuse element 3 is divided by the physical pulling action of the intermediate electrode 13 and the first and second electrodes 11, 12, so that the current path between the first and second electrodes 11, 12 can be quickly and reliably interrupted (FIG. 10).

[0074] Furthermore, by having a coating structure or a laminate structure in which the inner layer is the low melting point metal layer 26 and the outer layer is the high melting point metal layer 27, even if the reflow temperature exceeds the melting temperature of the low melting point metal layer 26, the high melting point metal layer 27, which has a melting point higher than the reflow temperature, suppresses deformation of the fuse element 3. Therefore, even if the conductive connecting material such as the connecting solder melts, it is possible to prevent the fuse element 3 from moving on the adhesion prevention portion 5 and even from coming off the first electrode 11, the second electrode 12, or the intermediate electrode 13.

[0075] Furthermore, the fuse element 3 may be configured so that the volume of the low melting point metal layer 26 is greater than the volume of the high melting point metal layer 27. The fuse element 3 is heated by self-heating due to an overcurrent or by heat generated by the heating element 6, and the low melting point metal melts and corrodes the high melting point metal, thereby enabling the fuse element 3 to melt and blow quickly. Therefore, by forming the volume of the low melting point metal layer 26 to be greater than the volume of the high melting point metal layer 27, the fuse element 3 can promote this corroding action and quickly cut off the connection between the first and second electrodes 11, 12.

[0076] Furthermore, in the fuse element 3 configured by laminating the high melting point metal layer 27 on the low melting point metal layer 26 which is the inner layer, the melting temperature can be significantly reduced compared to conventional chip fuses made of high melting point metal. Therefore, the fuse element 3 can have a larger cross-sectional area and a significantly improved current rating compared to chip fuses of the same size. Also, it can be made smaller and thinner than conventional chip fuses with the same current rating, and has excellent fast melting properties.

[0077] Furthermore, the fuse element 3 can improve resistance (pulse resistance) to surges in which an abnormally high voltage is instantaneously applied to an electric system in which the protective element 1 is incorporated. That is, the fuse element 3 must not melt even when, for example, a current of 100 A flows for several msec. In this regard, since a large current that flows in an extremely short time flows on the surface layer of a conductor (skin effect), the fuse element 3 has a high melting point metal layer 27 such as Ag plating with a low resistance value as an outer layer, so that the current applied by a surge can easily flow and melting due to self-heating can be prevented. Therefore, the fuse element 3 can significantly improve resistance to surges compared to fuses made of conventional solder alloys.

[0078] [Circuit configuration example] Such a protection element 1 is used by being incorporated into a circuit in a battery pack 40 of, for example, a lithium ion secondary battery, as shown in Fig. 11. The battery pack 40 has a battery stack 45 made up of, for example, a total of four battery cells 41a to 41d of lithium ion secondary batteries.

[0079] The battery pack 40 includes a battery stack 45, a charge / discharge control circuit 46 that controls charging and discharging of the battery stack 45, a protection element 1 to which the present invention is applied that cuts off a charge / discharge path when an abnormality occurs in the battery stack 45, a detection circuit 47 that detects the voltages of each of the battery cells 41a to 41d, and a current control element 48 that serves as a switch element that controls the operation of the protection element 1 in accordance with the detection result of the detection circuit 47.

[0080] The battery stack 45 is a series connection of battery cells 41a to 41d that require control to protect against overcharge and overdischarge, and is detachably connected to a charging device 42 via the positive terminal 40a and negative terminal 40b of the battery pack 40, and a charging voltage is applied from the charging device 42. The battery pack 40 charged by the charging device 42 can be used to operate an electronic device that runs on a battery by connecting the positive terminal 40a and negative terminal 40b to the electronic device.

[0081] The charge / discharge control circuit 46 includes two current control elements 43a, 43b connected in series to a current path between the battery stack 45 and the charging device 42, and a control unit 44 that controls the operation of these current control elements 43a, 43b. The current control elements 43a, 43b are, for example, field effect transistors (hereinafter referred to as FETs), and the control unit 44 controls the gate voltage to control the conduction and interruption of the current path of the battery stack 45 in the charging direction and / or discharging direction. Depending on the detection result by the detection circuit 47, when the battery stack 45 is overcharged or overdischarged, the control unit 44 controls the operation of the current control elements 43a, 43b so as to interrupt the current path.

[0082] The protection element 1 is connected, for example, on a charge / discharge current path between a battery stack 45 and a charge / discharge control circuit 46, and its operation is controlled by a current control element .

[0083] The detection circuit 47 is connected to each of the battery cells 41a-41d, detects the voltage value of each of the battery cells 41a-41d, and supplies each voltage value to the control unit 44 of the charge / discharge control circuit 46. The detection circuit 47 also outputs a control signal for controlling the current control element 48 when any one of the battery cells 41a-41d reaches an overcharge voltage or an overdischarge voltage.

[0084] The current control element 48 is composed of, for example, a FET, and when the detection signal output from the detection circuit 47 indicates that the voltage value of the battery cells 41a-41d exceeds a predetermined over-discharge or over-charge state, it operates the protection element 1 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 43a, 43b.

[0085] The protection element 1 to which the present invention is applied and used in the battery pack 40 configured as described above has a circuit configuration as shown in FIG. 12. That is, the first electrode 11 of the protection element 1 is connected to the battery stack 45 side, and the second electrode 12 is connected to the positive terminal 40a side, so that the fuse element 3 is connected in series to the charge / discharge path of the battery stack 45. In addition, the heating element 6 of the protection element 1 is connected to the current control element 48 via the heating element power supply electrode 8 and the third external connection electrode 19, and the heating element 6 is connected to the battery stack 45. As a result, one end of the heating element 6 is connected to the fuse element 3 and one end of the battery stack 45 via the heating element electrode 9 and the intermediate electrode 13, and the other end is connected to the current control element 48 and the other end of the battery stack 45 via the third external connection electrode 19. As a result, a power supply path to the heating element 6, the current supply of which is controlled by the current control element 48, is formed.

[0086] [Protection element operation] By mounting the protection element 1 on the external circuit board, the heating element 6 is connected to a current control element 48 and the like formed in the external circuit via the third external connection electrode 19, and electricity supply and heat generation are regulated under normal circumstances. When the detection circuit 47 detects an abnormal voltage in any of the battery cells 41a to 41d, it outputs a cutoff signal to the current control element 48. Then, the current control element 48 controls the current so that electricity is supplied to the heating element 6. When a current flows from the battery stack 45, the heating element 6 starts to generate heat.

[0087] The heat of the heating element 6 is transferred to the fuse element 3 via the heating element electrode 9 and the intermediate electrode 13, and also from the insulating layer 7 to the fuse element 3 via the intermediate electrode 13, melting the fuse element 3. In the fuse element 3, the molten conductor 3a condenses on the intermediate electrode 13 and is melted between the first electrode 11 and the second electrode 12 (FIG. 10). This makes it possible to cut off the charge / discharge path of the battery pack 40.

[0088] Furthermore, even when an overcurrent exceeding the rated current flows through the fuse element 3, the fuse element 3 melts due to self-heating and is blown between the first electrode 11 and the second electrode 12. This makes it possible to cut off the charge / discharge path of the battery pack 40.

[0089] In addition, by forming the fuse element 3 of the protective element 1 so that it contains 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 molten low-melting point metal can corrode the high-melting point metal, thereby dissolving the fuse element 3 in a short period of time.

[0090] When the fuse element 3 melts, the charge / discharge path of the battery stack 45 is cut off between the first electrode 11 and the second electrode 12. When the fuse element 3 melts, the power supply path to the heating element 6 is also cut off, and the heating element 6 stops generating heat.

[0091] The protective element 1 according to the present invention is not limited to use in a battery pack for a lithium ion secondary battery, and can of course be used in various applications that require the interruption of a current path by an electrical signal.

[0092] [Variation 1] Next, a modified example of a protection element to which the present technology is applied will be described. In the following description, the same components as those in the protection element 1 described above will be denoted by the same reference numerals, and the details thereof may be omitted. Fig. 13 shows a protection element 50 according to a modified example, where (A) is a plan view showing the protection element 50 without the cap member, (B) is an A-A' cross-sectional view shown in (A), (C) is a B-B' cross-sectional view shown in (A), and (D) is a bottom view.

[0093] 13(A) to 13(D), in a protective element 50 according to the modified example, a heating element 6, first and second extraction electrodes 17, 18, and an insulating layer 7 covering these are formed on a back surface 2b opposite to a front surface 2a of an insulating substrate 2. In addition, a heating element power supply electrode 8, a back surface heating element electrode 9b, and first and second external connection electrodes 15, 16 are formed on the back surface 2b of the insulating substrate 2.

[0094] Moreover, first and second electrodes 11, 12, an intermediate electrode 13 and an adhesion prevention portion 5 are formed on the surface 2a of the insulating substrate 2, and the fuse element 3 is mounted on each of these electrodes 11, 12, 13. Furthermore, a surface-side heating element electrode 9a is formed on the surface 2a of the insulating substrate 2 and is connected to the intermediate electrode 13.

[0095] The first and second electrodes 11, 12, and intermediate electrode 13 and front-side heating element electrode 9a provided on the front surface 2a of the insulating substrate 2, the heating element 6, first and second extraction electrodes 17, 18, heating element power supply electrode 8, rear-side heating element electrode 9b, and first and second external connection electrodes 15, 16 provided on the rear surface 2b of the insulating substrate 2 can be formed by a process similar to that of the protection element 1 described above.

[0096] The front-side heating element electrode 9a and the back-side heating element electrode 9b are electrically connected by castellations formed on the side surface of the insulating substrate 2, conductive through-holes penetrating the insulating substrate 2, or the like. That is, the intermediate electrode 13 is electrically and thermally connected to the heating element 6 via the front-side heating element electrode 9a and the back-side heating element electrode 9b. As a result, in the protective element 50, the heating element 6 heats the intermediate electrode 13 via the insulating substrate 2, and heat from the heating element 6 is transferred to the intermediate electrode 13 via the front-side heating element electrode 9a and the back-side heating element electrode 9b, which have excellent thermal conductivity, thereby heating and melting the fuse element 3.

[0097] In the protective element 50, the heating element power supply electrode 8 also serves as an external connection electrode to be connected to an electrode of an external circuit board, and therefore the third external connection electrode 19 provided in the protective element 1 is not provided.

[0098] Like the protective element 1, the protective element 50 forms an adhesion prevention portion 5 in the regions 10a and 10b, thereby making it possible to prevent the formation of a conductive path due to the continuous adhesion of soot-like material 14 between the first electrode 11 and the intermediate electrode 13 or between the second electrode 12 and the intermediate electrode 13, even when the current is interrupted.

[0099] [Variation 2] Furthermore, the protective element to which the present technology is applied may be an overcurrent interruption fuse that does not include the heating element 6. In this case, similarly to the protective elements 1 and 50, by forming the adhesion prevention portion 5 in the regions 10a and 10b, it is possible to prevent the formation of a conductive path caused by the continuous adhesion of the soot-like material 14 between the first electrode 11 and the intermediate electrode 13 and between the second electrode 12 and the intermediate electrode 13 when a current is interrupted. EXAMPLES

[0100] [First Example] Next, a first embodiment of the present technology will be described. In the first embodiment, a sample of a protective element having an adhesion prevention part formed thereon as an embodiment and a sample of a protective element having no adhesion prevention part formed thereon as a comparative example were prepared, and a current interruption test of the fuse element was performed by applying a predetermined power between the first and second electrodes. Then, after the current was interrupted, the insulation resistance (Ω) between the first and second electrodes was measured and evaluated.

[0101] The protective element sample of the embodiment has first and second electrodes 11, 12, a heating element power supply electrode 8, a heating element electrode 9, first and second extraction electrodes 17, 18, and a heating element 6 formed on a ceramic substrate using Ag patterns, and PB-free glass is laminated as an insulating layer 7.

[0102] 7, the protective element sample according to the embodiment had an adhesion prevention portion 5 made of a resin coating layer formed without gaps in the region 10a between the first electrode 11 and the intermediate electrode 13 and in the region 10b between the second electrode 12 and the intermediate electrode 13. The resin coating layer was formed by printing a resin material 5a (thermosetting epoxy adhesive: AH8455 series manufactured by Namics Corporation) by screen printing using a metal mask 22, and then curing by heating. The curing conditions were 100°C and 1.5 hours.

[0103] A stainless steel plate with a thickness of 0.06 mm was used for the metal mask 22. As shown in Fig. 14, the openings 21 had a width (0.55 mm) corresponding to the region 10a between the first electrode 11 and the intermediate electrode 13 and the region 10b between the second electrode 12 and the intermediate electrode 13, and a length (8.2 mm) covering at least the entire region between the first electrode 11 and the intermediate electrode 13 and between the second electrode 12 and the intermediate electrode 13. The interval between the openings 21 was set to the same width (0.9 mm) as the width of the intermediate electrode 13.

[0104] A fuse element having a coating structure in which a low melting point metal layer is coated with a high melting point metal layer was used as the fuse element 3. After forming the adhesion prevention part 5, two fuse elements 3 (2.2×1.5 mm, 0.08 mm thick) were mounted side by side between the first electrode 11 and the intermediate electrode 13 and between the second electrode 12 and the intermediate electrode 13 (see FIG. 15). Each of the electrodes 11 to 13 and the fuse element 3 were connected using solder paste (M705-GRN360-K2VZH manufactured by Senju Metal Industry Co., Ltd.).

[0105] Thereafter, flux was applied onto the fuse element 3 using a dispenser, and the cap member 24 was attached to the ceramic substrate, thereby obtaining a sample protection element.

[0106] The protective element sample according to the comparative example was the same as the protective element sample according to the example, except that the adhesion prevention portion 5 was not formed.

[0107] The powers applied to the protective elements according to the examples and comparative examples were 160A-100V and 240A-100V. The number of samples in the examples and comparative examples for each applied power was 6. The following instruments were used in the current interruption test and in measuring the insulation resistance (Ω) between the first and second electrodes after the current was interrupted. Power supply: Takasago Manufacturing, HX0150-300 Electronic load: Keisoku Giken, 34230 Insulation resistance tester: Hioki, DSM-8104 Cable: AWG6

[0108] The insulation resistance after current interruption is 1.0×10 6 If the resistance was less than 100 Ω, it was deemed impossible to measure. The measurement results are shown in Table 1. In Table 1, the fuse resistance (mΩ) is the resistance value between the first and second electrodes 11, 12 of the sample before it was blown.

[0109] [Table 1]

[0110] As shown in Table 1, in the comparative example without the adhesion prevention part, except for one sample, the insulation resistance was low and could not be measured. However, in the example with the adhesion prevention part 5, all the samples were measurable (1.0×10 6 This shows that the provision of the adhesion prevention portion 5 increases the insulation resistance.

[0111] FIG. 16 is a graph showing the current-time characteristics when a power of 240 A-100 V is applied to an example sample provided with an adhesion prevention part 5 and the current is interrupted, where (A) shows the period from before the power is applied until after the current is interrupted, and (B) shows an enlarged view of the area around the time of current interruption.

[0112] FIG. 17 is a graph showing the current-time characteristics when a power of 240 A-100 V is applied to a comparative sample not provided with an adhesion prevention part 5 and the current is interrupted, where (A) shows the period from before the power is applied until after the current is interrupted, and (B) shows an enlarged view of the area around the time of current interruption.

[0113] In the embodiment in which the adhesion prevention portion was provided, the current waveform oscillated greatly and then immediately dropped linearly in a jagged manner. In the comparative example, there was a portion where the current waveform oscillated greatly just before the cutoff (arrow), and the current dropped in a curved manner a short time later. In the comparative example, it took a long time from the current waveform oscillated greatly (arrow) until the current finally dropped.

[0114] In both the Examples and Comparative Examples, an explosion occurred when the current was interrupted, causing a mixture of the melted fuse element, flux, and parts of the electrodes to scatter, resulting in the deposition of black soot-like material on the ceramic substrate surface. In the Comparative Examples, the soot-like material was thickly deposited on all samples except Comparative Example 1, where the insulation resistance was measured. In contrast, the soot-like material was only thinly deposited on the Examples. The lower the insulation resistance of the sample, the darker the black color, and the greater the degree of damage caused by the explosion when the current was interrupted.

[0115] In the comparative example, the fuse element as well as the first and second electrodes, intermediate electrode, and insulating layer appear to have been blown away. In the working example, the first and second electrodes and intermediate electrode were partially damaged, but the resin coating layer (adhesion prevention portion) remained almost intact. In the working example, there were also some areas where a black soot-like substance appeared to have peeled off from the surface of the resin coating layer.

[0116] From the results shown in Table 1 and FIGS. 16 and 17, and the observation results of each sample of the Example and Comparative Example after meltdown, the behavior of each sample of the Example and Comparative Example when current is interrupted is considered to be as follows.

[0117] In the comparative example in which no adhesion prevention portion is provided, the molten conductor of the fuse element is scattered by the explosion when the current is interrupted, and soot-like substances are attached to the electrodes and glass, forming another conductive path. Current also flows through this conductive path, but since it has a higher resistance than the fuse element, the power applied is also high. The high power heats up the conductive path, causing the electrodes and glass to melt and explode while being engulfed in them, and another conductive path is formed again, which induces a further explosion, repeating the cycle. As a result, it is believed that the soot-like substances are densely attached to the entire surface of the substrate, causing a decrease in the insulation resistance value after the current is interrupted.

[0118] In the embodiment in which the adhesion prevention portion is provided, the adhesion of soot-like substances generated when the current is interrupted is suppressed in the resin coating layer, and another conductive path is less likely to be generated. As a result, the cycle of further explosions and the generation of conductive paths due to the formation of another conductive path is reduced, and the adhesion of soot-like substances to the substrate surface and the degree of damage to the electrodes are also reduced, which is considered to have resulted in a high insulation resistance after the current is interrupted.

[0119] [Second Example] Next, a second embodiment of the present technology will be described. In the second embodiment, the formation range of the adhesion prevention portion 5 was changed, and the fuse resistance of each sample before melting was measured and evaluated. The protective element sample according to the second embodiment and the manufacturing process thereof have the same configuration as the embodiment sample according to the first embodiment described above, so details will be omitted.

[0120] [Example 13] As Example 13, a protective element sample was formed in which the adhesion prevention part 5 was not in contact with any of the first and second electrodes 11 and 12 and the intermediate electrode 13 (see FIG. 4).

[0121] [Example 14] As Example 14, a protective element sample was formed in which the adhesion prevention portion 5 overlapped the first and second electrodes 11 and 12 (see FIG. 6(B)).

[0122] [Example 15] As Example 15, a protective element sample in which the adhesion prevention portion 5 overlaps the first and second electrodes 11 and 12 and the intermediate electrode 13 was formed.

[0123] A current of 1 A was applied to the protection element samples according to Examples 13 to 15, and the voltage between the second electrodes 11 and 12 was measured, from which the fuse resistance value was calculated.

[0124] [Table 2]

[0125] As shown in Table 2, Example 13, in which the adhesion prevention part 5 was provided so as not to contact any of the first and second electrodes 11 and 12, and the intermediate electrode 13, had the lowest fuse resistance value. Furthermore, although this is not a problem in practical use, Example 15, in which the adhesion prevention part 5 was provided so as to overlap any of the first and second electrodes 11 and 12, and the intermediate electrode 13, had the highest fuse resistance value.

[0126] From Table 2 and the observation results of the samples according to Examples 13 to 15, the following can be considered. If the resin material 5a overlaps the first and second electrodes 11, 12 or the intermediate electrode 13, that portion cannot be connected to the fuse element. Therefore, it is considered that a part of the low-resistance electrode is removed from the current path, resulting in high fuse resistance. Therefore, in order to reduce the fuse resistance value, it is preferable not to overlap the material constituting the adhesion prevention portion 5 with the first and second electrodes 11, 12 or the intermediate electrode 13. [Explanation of symbols]

[0127] 1 protection element, 2 insulating substrate, 2a front surface, 2b rear surface, 3 fuse element, 4 flux, 5 adhesion prevention portion, 6 heating element, 7 insulating layer, 8 heating element power supply electrode, 9 heating element electrode, 10 region, 11 first electrode, 12 second electrode, 13 intermediate electrode, 14 soot-like substance, 15 first external connection electrode, 16 second external connection electrode, 17 first lead-out electrode, 18 second lead-out electrode, 19 third external connection electrode, 21 opening, 22 mask, 23 squeegee, 24 cap member, 26 low melting point metal layer, 27 high melting point metal layer, 40 battery pack, 41 battery cell, 42 charging device, 43 current control element, 44 control portion, 45 battery stack, 46 charge / discharge control circuit, 47 detection circuit, 48 current control element, 50 protection element

Claims

1. An insulating substrate; a first electrode and a second electrode provided on the insulating substrate; an intermediate electrode disposed between the first electrode and the second electrode; a fuse element disposed on a surface of the first electrode, the second electrode, and the intermediate electrode to electrically connect between the first electrode and the intermediate electrode and between the second electrode and the intermediate electrode; an adhesion prevention portion provided between the first electrode and the intermediate electrode and / or between the second electrode and the intermediate electrode, the adhesion prevention portion suppressing adhesion of molten spatter of the fuse element; Protection element.

2. 2. The protective element according to claim 1, wherein the adhesion prevention portion is a cured product of an epoxy resin, a fluorine-based resin or a silicone resin.

3. 3. The protective element according to claim 1, wherein the adhesion prevention portion is provided in at least the entire region between the first electrode and the intermediate electrode and / or the entire region between the second electrode and the intermediate electrode.

4. The protective element according to claim 1 , wherein the adhesion prevention portion is provided in contact with the intermediate electrode or overlaps the intermediate electrode.

5. The protective element according to claim 1 , wherein the adhesion prevention portion is provided in contact with the first electrode and / or the second electrode, or overlaps with the first electrode and / or the second electrode.

6. After the fuse element melts, the insulation resistance is 1×10 ６ The protection element according to claim 1 or 2, wherein the resistance is higher than Ω.

7. A heating element provided on the insulating substrate; An insulating layer is provided to cover the heating element. The protection element according to claim 1 or 2.

8. the heating element and the insulating layer are formed on a surface of the insulating substrate on which the fuse element is provided, The protection element according to claim 7 , wherein the intermediate electrode is laminated on the insulating layer.

9. 8. The protection element according to claim 7, wherein the heating element and the insulating layer are formed on a back surface of the insulating substrate opposite to a front surface on which the fuse element is provided.

10. The protection element according to claim 7 , wherein the heating element is connected to the intermediate electrode.

11. The battery storage device includes one or more battery cells, and a protection element connected to a charge / discharge path of the battery cell and blocking the charge / discharge path; The protection element is the protection element according to claim 1 or 2. Battery pack.

Images