Protection element and battery pack

Abstract

To provide a protection element capable of improving an insulation property after fusion of a fuse element, and provide a battery pack using them.SOLUTION: A protection element comprises: a case 2; a fuse element 3; a pair of fuse terminals 4a and 4b that is connected to the fuse element 3; and a fusion member 5 that is connected to at least one surface of the fuse element 3, and fuses the fuse element 3. The fusion member 5 comprises: an insulation substrate 6; and an intermediate electrode 7 that is provided to a front surface 6a contacted to the fuse element 3 of an insulation substrate 6, and is connected to the fuse element 3. In at least one of the insulation substrate 6 and the pair of fuse terminals 4a and 4b, a space 10 is provided to an upper side and a lower side of the fuse element 3. In a region where the fuse element 3 and the insulation substrate 6 are overlapped, a space 11 is provided to the upper side and the lower side of the fuse element 3 and the insulation substrate 6.SELECTED DRAWING: Figure 3

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] In recent years, lithium-ion batteries have expanded from their use in mobile devices to applications such as EVs (Electric Vehicles) and storage batteries, and the current capacity is becoming larger. Because these batteries have the risk of catching fire in the event of an abnormality, the mainstream method of ensuring product safety as capacity increases is to incorporate protection circuits using protection elements.

[0003] There are two types of protective elements: current fuses that protect against overcurrent, and fuses that protect against overcurrent and overvoltage. Current fuses that protect against overcurrent are connected in series with electric circuits and immediately cut off the current path when an overcurrent occurs due to an electrical short circuit or the like inside the equipment, protecting the wires and equipment that make up the circuit from accidents such as fire. Overcurrent protection fuses have a relatively simple structure, and when an overcurrent flows, the fusible conductor element part of the fuse, which has a small cross-sectional area, reaches its melting point due to Joule heat and melts, cutting off the current path.

[0004] Examples of overcurrent protection fuses include glass tube fuses, blade fuses, slow-blow fuses, and EV fuses. Glass tube fuses are used, for example, to protect against overcurrent when the engine is ignited. Blade fuses have a simpler structure than glass tube fuses, and, like glass tube fuses, are used, for example, as fuses for automobiles. Slow-blow fuses are used to protect against overcurrent in motor parts used in power windows, automatic wipers, air conditioners, and other components installed in automobiles. EV fuses are used to protect against overcurrent in the electrical systems of hybrid and electric automobiles, which, unlike gasoline-powered automobiles, are high-voltage.

[0005] Fuses that provide overvoltage protection in addition to overcurrent protection are mainly equipped with a heating element, which melts down when the heating element generates heat.Specifically, when an IC that monitors the voltage and temperature of a lithium-ion battery detects an abnormality, it transmits the signal to an FET that functions as an ON / OFF switch, and when the FET is in the ON state, electricity begins to flow to the heating element, and the heat from the heating element, which heats up due to the current, melts the fuse and cuts off the current path.

[0006] In both types of protection elements, whether overcurrent protection or overvoltage protection, if an abnormality is detected, it is necessary to quickly shut off the circuit for safety. In addition, the protection element is generally constructed of a thick-film printed circuit board and a fuse element (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0007] [Patent Document 1] JP 2015-053260 A Summary of the Invention [Problem to be solved by the invention]

[0008] 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.

[0009] Here, if the rated voltage of the current is increased, sparks (discharges) are more likely to occur between the electrodes after the fuse element melts, and the repetition of these sparks causes a tracking phenomenon, which may also impede the melting of the fuse element, lead to failure to cut, or otherwise deteriorate the insulation of the fuse element after melting.

[0010] Furthermore, increasing the rated voltage can be achieved by increasing the size of the components, but expanding the internal space of the case not only increases the size of the components, but also increases costs and makes it less convenient for users.

[0011] In order to increase the current capacity, it is possible to increase the volume of the fuse element or the thickness of the conductor on the insulating substrate, but as the volume of the fuse element increases or the conductor thickness increases, the impact when the fuse element melts becomes more severe, and there is a risk that the insulation after melting will deteriorate due to adhesion of molten debris, etc. In addition, after the fuse element melts, a tracking phenomenon is likely to occur via the molten debris.

[0012] Fig. 30 shows an example of a conventional protection element 100 compatible with high voltages, where (A) is a plan view, (B) is a D-D' cross-sectional view of (A), and (C) is a P-P' cross-sectional view of (A). Fig. 31 shows a plan view of the protection element 100 without the upper case, where (A) is a schematic diagram showing the state before operation, (B) is a state where cutoff has occurred due to self-heating caused by an overcurrent, and (C) is a state after cutoff.

[0013] As shown in Figs. 30 and 31, the protection element 100 includes a pair of upper and lower cases 101, a fuse element 102 made of a fusible conductor, and a fusing member 103 for fusing the fuse element 102. The fusing member 103 includes an insulating substrate 104, an intermediate electrode 105 connected to the fuse element 102, and a heating element 106 that generates heat when current is applied to fuse the fuse element 102. The lower case 101a has a pair of fuse terminals 107 and 108 connected to the fuse element 102 and a heating element terminal 109 connected to the heating element 106 mounted on its side edges, and the insulating substrate 104 mounted on its center. The heating element 106 has one end connected to the intermediate electrode 105 and the other end connected to an external power source via the heating element terminal 109.

[0014] The fuse element 102 is connected to the fuse terminals 107, 108 and the intermediate electrode 105 by a conductive material such as solder. The fuse element 102 is overlapped with the heating element 106 via the insulating layer and the intermediate electrode 105. The fuse terminals 107, 108 of the protective element 100 are connected to terminals of an external circuit, so that the fuse element 102 is incorporated into the current path of the external circuit. When electricity is applied to the heating element 106 from an external power source, the protective element 100 melts the fuse element 102 by the heat of the heating element 106. When an abnormal current flows through the external circuit, the fuse element 102 melts due to self-heating (Joule heat), thereby interrupting the current path of the external circuit.

[0015] Here, in conventional protective elements compatible with high voltages, the rated voltage is limited to about 80 V, and at a voltage higher than this, for example 100 V or higher, the blowout shock of fuse element 102 also becomes large, and soot-like debris 102a from melted fuse element 102 adheres to the inner surface of the case and the surface of the insulating substrate (see FIG. 31(C)). As a result, after fuse element 102 blows, a spark (discharge) occurs between fuse terminal 107-insulating substrate 104-fuse terminal 108, and there is a risk of tracking occurring thereafter.

[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 a case, a fuse element housed in the case, a pair of fuse terminals spaced apart in the current flow direction of the fuse element and supported on a side portion of the case and connected to the fuse element, and a fusing member connected to at least one surface of the fuse element between the pair of fuse terminals and fusing the fuse element, the fusing member including an insulating substrate and an intermediate electrode provided on a surface of the insulating substrate in contact with the fuse element and connected to the fuse element, a space is provided above and below the fuse element between the insulating substrate and at least one of the pair of fuse terminals, and a space is provided above and below the fuse element and the insulating substrate in a region where the fuse element and the insulating substrate overlap.

[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] According to this technology, since there is a space between the fuse terminal and the insulating substrate, the Joule heat of the fuse element is difficult to dissipate between the fuse terminal and the intermediate electrode. Also, since there is a space above and below the fuse element and the insulating substrate, the fuse element expands spherically on the surface of the insulating substrate when melted, and the molten conductor aggregates on the intermediate electrode and the fuse terminal, and the Joule heat of the fuse element is difficult to dissipate. As a result, the fuse element is heated over a wide area, and the explosive thermal shock caused when the fuse element reaches its melting point and melts is dispersed and mitigated. Therefore, according to this technology, even in the case of self-heating interruption due to an overcurrent at a high voltage, it is possible to safely interrupt the circuit, and also to suppress the deterioration of insulation caused by molten debris. [Brief description of the drawings]

[0020] [Figure 1] FIG. 1 is a top view of a protection element to which the present technology is applied. [Diagram 2] FIG. 2 is a plan view showing the protective element with the upper case omitted. [Diagram 3] FIG. 3 is a cross-sectional view taken along line DD' of FIG. [Figure 4] FIG. 4 is a cross-sectional view taken along line P-P' of FIG. [Diagram 5] FIG. 5 is a diagram showing the upper and lower cases, where (A) is a plan view of the upper case, (B) is a plan view of the lower case, and (C) is a cross-section showing the upper and lower cases butted together. [Figure 6] FIG. 6 is a diagram showing a fusing member, where (A) is a plan view and (B) is a bottom view. [Figure 7] FIG. 7 is a cross-sectional view showing an example of a fuse element. [Figure 8] FIG. 8 is a cross-sectional view showing a state in which the fuse element of the protection element shown in FIG. 3 has been blown. [Figure 9] FIG. 9 is a circuit diagram showing an example of the configuration of a battery pack. [Figure 10] FIG. 10 is a circuit diagram of a protection element. [Figure 11] FIG. 11 is a cross-sectional view showing a protection element in which a heating element is formed on the back surface of an insulating substrate. [Figure 12] FIG. 12 is a plan view showing the protective element shown in FIG. 11 with the upper case omitted. [Figure 13] 13A and 13B are diagrams showing an insulating substrate of the protection element shown in FIG. 11, where (A) is a plan view and (B) is a bottom view. [Figure 14] FIG. 14 is a cross-sectional view showing a protective element in which a holding electrode is formed on the back surface of an insulating substrate. [Figure 15] FIG. 15 is a plan view showing the protective element shown in FIG. 14 with the upper case omitted. [Figure 16] 16A and 16B are diagrams showing an insulating substrate of the protection element shown in FIG. 14, where (A) is a plan view and (B) is a bottom view. [Figure 17]FIG. 17 is a cross-sectional view showing a state in which the fuse element of the protection element shown in FIG. 14 is blown. [Figure 18] FIG. 18 is a circuit diagram of the protection element shown in FIG. [Figure 19] FIG. 19 is a cross-sectional view showing a protective element in which a heating element, an insulating layer, and a holding electrode are formed on the rear surface of an insulating substrate. [Figure 20] FIG. 20 is a plan view showing the protective element shown in FIG. 19 with the upper case omitted. [Figure 21] 21A and 21B are diagrams showing an insulating substrate of the protection element shown in FIG. 19, where (A) is a plan view and (B) is a bottom view. [Figure 22] FIG. 22 is a cross-sectional view showing a state in which the fuse element in the protection element shown in FIG. 19 is blown. [Diagram 23] FIG. 23 is a cross-sectional view showing a protection element in which a fusing member having a heating element formed on the surface of an insulating substrate is connected to one surface and the other surface of a fuse element. [Figure 24] FIG. 24 is a plan view showing the protective element shown in FIG. 23 with the upper case omitted. [Diagram 25] FIG. 25 is a circuit diagram of the protection element shown in FIG. [Figure 26] FIG. 26 is a cross-sectional view showing a state in which the fuse element of the protection element shown in FIG. 23 is blown. [Figure 27] FIG. 27 is a cross-sectional view showing a protection element in which a fusing member having a heating element formed on the rear surface of an insulating substrate is connected to one surface and the other surface of a fuse element. [Figure 28] FIG. 28 is a plan view showing the protective element shown in FIG. 27 with the upper case omitted. [Figure 29] FIG. 29 is a cross-sectional view showing a state in which the fuse element in the protection element shown in FIG. 27 is blown. [Diagram 30] FIG. 30 shows an example of a conventional protection element 100 that can withstand high voltages, where (A) is a plan view and (B) is a DD' cross-sectional view of (A). [Diagram 31]FIG. 31 is a plan view showing the protection element 100 with the upper case omitted, in which (A) is a schematic showing the state before operation, (B) is a schematic showing the state after shutdown due to self-heating caused by an overcurrent, and (C) is a schematic showing the state after shutdown. 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] [Protection element] FIG. 1 is a top view of a protection element 1 to which the present technology is applied, FIG. 2 is a plan view showing the protection element 1 without the upper case, FIG. 3 is a cross-sectional view taken along the line D-D' in FIG. 1, and FIG. 4 is a cross-sectional view taken along the line P-P' in FIG. 1.

[0023] As shown in Figs. 1 to 4, a protection element 1 to which the present invention is applied includes a case 2, a fuse element 3 housed in the case 2, a pair of fuse terminals 4a, 4b supported on the side surface of the case 2 and spaced apart in the current-carrying direction of the fuse element 3 and connected to the fuse element 3, and a fusing member 5 connected to at least one surface of the fuse element 3 between the pair of fuse terminals 4a, 4b and fusing the fuse element 3. The fusing member 5 includes an insulating substrate 6 and an intermediate electrode 7 provided on a surface 6a of the insulating substrate 6 that contacts the fuse element 3 and connected to the fuse element 3. The protection element 1 has a space 10 above and below the fuse element 3 between the insulating substrate 6 and at least one of the pair of fuse terminals 4a, 4b, and has a space 11 above and below the fuse element 3 and the insulating substrate in a region where the fuse element 3 and the insulating substrate 6 overlap.

[0024] The fuse element 3 is connected to the intermediate electrode 7 and the pair of fuse terminals 4a, 4b by a joining material such as a connection solder 13. The fuse terminals 4a, 4b of the fuse element 3 are connected to terminals on the current path of an external circuit, and the fuse element 3 is incorporated into a part of the current path of the external circuit. The fuse element 3 will not melt even due to self-heating (Joule heat) while a specified rated current is flowing. 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 fuse terminals 4a, 4b.

[0025] In such a protection element 1, because there is a space 10 between the fuse terminals 4a, 4b and the insulating substrate 6, it becomes difficult for the Joule heat of the fuse element 3 to be dissipated between the fuse terminals 4a, 4b and the intermediate electrode 7. In addition, because there are spaces 11 above and below the fuse element 3 and the insulating substrate 6, the fuse element 3 expands spherically on the surface 6a of the insulating substrate 6 when melted, and the molten conductor coagulates on the intermediate electrode 7 and the fuse terminals, making it difficult for the Joule heat of the fuse element 3 to be dissipated.

[0026] This allows the fuse element 3 to be heated over a wide area, dispersing and mitigating the explosive thermal shock that occurs when the fuse element 3 reaches its melting point and melts. Therefore, the protection device 1 can safely cut off power even in the event of self-heating caused by a high-voltage overcurrent, and can also prevent deterioration of insulation caused by molten debris.

[0027] The case 2, fuse element 3, fuse terminals 4a and 4b, and fusing member 5 that constitute the protective element 1 will be described in detail below.

[0028] [case] The case 2 can be formed using insulating materials such as various engineering plastics, thermoplastic plastics, ceramics, glass epoxy boards, etc. The case 2 houses the fuse element 3 and the fusing member 5, and supports the fuse terminals 4a, 4b and the heating element terminal 15, leading them to the inside and outside of the case. The case 2 also has an internal space sufficient for the molten conductor 3a to expand spherically when the fuse element 3 melts and to aggregate on the intermediate electrode 7 and the fuse terminals 4a, 4b.

[0029] As shown in Fig. 3 and Fig. 4, the case 2 is formed by combining an upper case 21 and a lower case 22. Fig. 5 shows the upper case 21 and the lower case 22, where (A) is a plan view of the upper case 21, (B) is a plan view of the lower case 22, and (C) is a cross-sectional view showing the upper case 21 and the lower case 22 butted together. The upper case 21 has a mating recess 23 formed on the lower surface of the side wall. The lower case 22 has a mating protrusion 24 formed on the upper surface of the side wall to fit into the mating recess 23. The upper and lower cases 21 and 22 are combined by fitting the mating protrusion 24 into the mating recess 23, and are fixed by adhesive 25 provided on the upper and lower surfaces of the side walls.

[0030] As shown in FIG. 5B, the lower case 22 is formed in a substantially rectangular shape, has a side edge 22a in which a fitting protrusion 24 is formed and which supports fuse terminals 4a, 4b and a heating element terminal 15, which will be described later, and a hollow portion 22b, which is provided as an area surrounded by the side edge 22a and in which a fusing member 5 connected to the fuse element 3 is located. The side edge 22a is formed by protruding over the entire inner circumference of the lower case 22, on which the fuse terminals 4a, 4b and the heating element terminal 15 are placed, and supports the case 2 from inside to outside. As shown in FIG. 3 and FIG. 4, the fuse terminals 4a, 4b and the heating element terminal 15 are supported so that their tip surfaces are flush with the inner end of the side edge 22a. The hollow portion 22b is where the fusing member 5 connected to the fuse element 3 is located, and has an internal space below the fusing member 5, so that the fusing member 5 can be held in the air.

[0031] 5(A), upper case 21 is formed in a substantially rectangular shape like lower case 22, and is butt-joined to lower case 22 to cover fuse element 3 and fusing member 5 connected to fuse element 3. Upper case 21 also has an internal space above fuse element 3 where molten conductor 3a can wet, spread and coagulate over fuse terminals 4a, 4b and intermediate electrode 7.

[0032] [Fuse terminal] The fuse terminals 4a, 4b can be formed using known terminal materials such as pure copper, copper alloy, etc. The fuse terminals 4a, 4b have, for example, a rectangular plate shape, are spaced apart in the current-carrying direction of the fuse element 3, are supported by a side edge portion 22a of the lower case 22, and are led out from inside the case 2 to the outside.

[0033] The fuse terminals 4a, 4b have screw holes 14 at their tips that are extended to the outside of the case 2, and can be connected to connection electrodes provided on an external circuit by screwing or the like. The fuse terminals 4a, 4b are connected to the ends of the fuse element 3 by a joining material such as connection solder 13. Note that the screw holes 14 may not be provided and connection may be made using connection solder or the like.

[0034] As a result, the fuse terminals 4a, 4b are electrically connected via the fuse element 3. Furthermore, the connection is interrupted when the fuse element 3 is melted.

[0035] [Fused material] The fusing member 5 is connected to at least one surface of the fuse element 3 between the pair of fuse terminals 4a, 4b, and serves to fuse the fuse element 3.

[0036] [Insulating substrate] The fusing member 5 includes an insulating substrate 6. The insulating substrate 6 is formed of an insulating material such as alumina, glass ceramics, mullite, or zirconia. Alternatively, the insulating substrate 6 may be made of a material used for printed wiring boards, such as a glass epoxy board or a phenol board. An intermediate electrode 7 connected to the fuse element 3 is formed on a surface 6a of the insulating substrate 6.

[0037] Moreover, the insulating substrate 6 is physically connected to the fuse element 3 via the intermediate electrode 7 formed on the front surface 6a. In the insulating substrate 6 according to the present technology, as shown in Figs. 2 to 4, the surface on which the intermediate electrode 7 connected to the fuse element 3 is formed is referred to as the front surface 6a, and the surface opposite to the front surface 6a is referred to as the back surface 6b.

[0038] [Intermediate electrode] The intermediate electrode 7 is formed of a conductive pattern of Ag, Cu, etc. In addition, the surface of the intermediate electrode 7 is preferably coated with a coating such as Ni / Au plating, Ni / Pd plating, Ni / Pd / Au plating, etc. by a known method such as plating.

[0039] [Heater / insulating layer] A protection element to which the present technology is applied preferably includes, on an insulating substrate 6, a heating element 8 that melts the fuse element 3 by generating heat, and an insulating layer 9 that covers the heating element 8. In the protection element 1 shown in Figs. 2 to 4, the heating element 8 and the insulating layer 9 are provided on a surface 6a of the insulating substrate 6.

[0040] Heating element 8 is a conductive member that has a relatively high resistance and generates heat when electricity is passed through it, and is made of, for example, nichrome, W, Mo, Ru, etc., or materials containing these. Heating element 8 can be formed by mixing powder of these alloys, compositions, or compounds with a resin binder or the like to make a paste, forming a pattern on insulating substrate 6 using a screen printing technique, and firing the paste.

[0041] 6, one end of the heating element 8 is connected to a heating element power supply electrode 16, and the other end is connected to a heating element electrode 17. The heating element power supply electrode 16 is an electrode connected to one end of the heating element 8 and serves as a power supply terminal to the heating element 8, and is connected to a heating element terminal 15 via a connection solder 13 (see FIGS. 2 and 4). The heating element 8 is covered with an insulating layer 9, and an intermediate electrode 7 formed on the insulating layer 9 is superimposed thereon.

[0042] Heating element terminal 15 has the same material and shape as fuse terminals 4a, 4b described above, and is supported by side edge 22a of lower case 22 in the same manner as fuse terminals 4a, 4b, and is led out from inside case 2 to the outside. Heating element terminal 15 has screw hole 14 at the tip led out to the outside of case 2, so that it can be connected to a connection electrode provided on an external circuit by screwing or the like.

[0043] 4, the heating element terminals 15 and the insulating substrate 6 are provided at approximately the same height, and the sides of the heating element terminals 15 and the insulating substrate 6 are in close contact with each other via the connecting solder 13. As a result, the insulating substrate 6 is held in the hollow portion 22b by the connecting solder 13 applied from the heating element power supply electrodes 16 to the heating element terminals 15. In other words, the insulating substrate 6 is held in a hollow state in the hollow portion 22b, except for being connected to the case 2 via the heating element terminals 15.

[0044] The heating element power supply electrode 16 is connected to a power source provided in the external circuit by being connected to the heating element terminal 15 connected to an external circuit, and is thereby capable of supplying power to the heating element 8. The heating element electrode 17 is also connected to the intermediate electrode 7 described above. As a result, the intermediate electrode 7 functions as a heating element extraction electrode connected to the heating element 8 via the heating element electrode 17.

[0045] The heating element power supply electrode 16 and the heating element electrode 17 are each formed of a conductive pattern of Ag, Cu, or the like. In addition, the surfaces of the heating element power supply electrode 16 and the heating element electrode 17 are preferably coated with a coating such as Ni / Au plating, Ni / Pd plating, Ni / Pd / Au plating, or the like by a known method such as plating. This allows the protective element 1 to prevent oxidation of the heating element power supply electrode 16 and the heating element electrode 17 and to prevent fluctuations in the rating due to an increase in the conductive resistance.

[0046] The insulating layer 9 is provided to protect and insulate the heating element 8, and is made of, for example, a glass layer. The insulating layer 9 is formed to be thin, for example, 10 to 40 μm. The insulating layer 9 may also be formed between the surface 6a of the insulating substrate 6 and the heating element 8.

[0047] [Auxiliary electrode] An auxiliary electrode 18 is provided on the surface 6a of the insulating substrate 6. The auxiliary electrode 18, together with the intermediate electrode 7, is connected to the fuse element 3 by a bonding material such as a connection solder 13, and holds the molten conductor 3a. The auxiliary electrodes 18 are formed on both side edges of the insulating substrate 6 in the extension direction of the fuse element 3, sandwiching the intermediate electrode 7 therebetween.

[0048] [Forming process of fusing components] The fusing member 5 is formed by forming a heating element power supply electrode 16, a heating element electrode 17, and an auxiliary electrode 18 on the surface 6a of the insulating substrate 6, all of which are formed by using a known forming method such as screen printing, followed by forming the heating element 8 and laminating the insulating layer 9. Next, the intermediate electrode 7 is formed. The fusing member 5 has the intermediate electrode 7 and the auxiliary electrode 18 connected to the fuse element 3 by the connection solder 13. The fuse element 3 to which the fusing member 5 is connected is connected to the fuse terminals 4a and 4b supported by the side edge portion 22a of the lower case 22 by the connection solder 13. In addition, the heating element power supply electrode 16 of the insulating substrate 6 is connected to the heating element terminal 15 supported by the side edge portion 22a of the lower case 22 by the connection solder 13.

[0049] [space] 3, in the protection element 1 to which the present technology is applied, the intermediate electrode 7 and the fuse element 3 are connected, and the heating element power supply electrode 16 is connected to the heating element terminal 15, so that the fusing member 5 is held in the air within the case 2. As a result, a space 10 is formed above and below the fuse element 3 between the insulating substrate 6 and at least one, preferably both, of the pair of fuse terminals 4a, 4b, and a space 11 is formed above and below the fuse element 3 and the insulating substrate 6 in a region where the fuse element 3 and the insulating substrate 6 overlap each other.

[0050] In such a protection device 1, when an abnormal current flows through the fuse element 3, because there is a space 10 between the fuse terminals 4a, 4b and the insulating substrate 6, it becomes difficult for the Joule heat of the fuse element 3 to be dissipated between the fuse terminals 4a, 4b and the intermediate electrode 7. In addition, because there are spaces 11 above and below the fuse element 3 and the insulating substrate 6, the fuse element 3 expands spherically on the surface 6a of the insulating substrate 6 when melted, and the molten conductor coagulates on the intermediate electrode 7 and the fuse terminals, making it difficult for the Joule heat of the fuse element 3 to be dissipated.

[0051] This allows the fuse element 3 to be heated over a wide area, dispersing and mitigating the explosive thermal shock that occurs when the fuse element 3 reaches its melting point and melts. Therefore, the protection device 1 can safely cut off the circuit even in the event of self-heating caused by an overcurrent at a high voltage. It also prevents sparks and tracking caused by molten debris, and suppresses deterioration of insulation properties.

[0052] [D3≧7mm] In the protective element 1, the greater the distance D3 between the pair of fuse terminals 4a, 4b in the cross-sectional view of the extension direction of the fuse element 3 shown in Fig. 3, the more preferable it is, and in particular, D3 is preferably 7 mm or more. That is, from the viewpoint of suppressing the dissipation of Joule heat from the fuse element 3, the greater the distance D3 between the pair of fuse terminals 4a, 4b is, the more preferable it is, but the greater the distance between the fuse terminals 4a, 4b, the higher the resistance value between the terminals. Therefore, in order to increase the current, it becomes necessary to increase the volume of the fuse element 3. Setting the distance D3 between the fuse terminals 4a, 4b to 7 mm or more is preferable in order to increase the current rating and the voltage while miniaturizing the component.

[0053] [D1, D2 ≧ 1mm] 3, the protective element 1 preferably has a distance D1 of 1 mm or more between one fuse terminal 4a and one side edge portion of the insulating substrate 6 facing the fuse terminal 4a. The protective element 1 has a space 10 above and below the fuse element between the insulating substrate 6 and one fuse terminal 4a, and the distance of the space 10 is defined as the distance D1 between the fuse terminal 4a and the side edge portion of the insulating substrate 6 in the cross-sectional view of the fuse element 3 in the extension direction.

[0054] That is, the protective element 1 does not include a configuration in which the fuse terminal 4a overlaps the insulating substrate 6 (D1<0 mm) or a configuration in which the fuse terminal 4a contacts the insulating substrate 6 (D1=0 mm).

[0055] In addition, by making the distance D1 of the protective element 1 equal to or greater than 1 mm, and more preferably greater than 1 mm, the effect of suppressing heat dissipation from the fuse element 3 can be more effectively achieved.

[0056] For the same reason, in the protective element 1, in a cross-sectional view in the extending direction of the fuse element 3 shown in Fig. 3, it is preferable that the distance D2 between the other fuse terminal 4b and the other side edge of the insulating substrate 6 facing the fuse terminal 4b is 1 mm or more. In other words, the protective element 1 does not have a configuration in which the fuse terminal 4b overlaps the insulating substrate 6 (D2<0 mm) or a configuration in which the fuse terminal 4b contacts the insulating substrate 6 (D2=0 mm).

[0057] [W <D3] 3, the width W of the insulating substrate 6 in the direction between the pair of fuse terminals 4a, 4b of the protective element 1 is smaller than the distance D3 between the pair of fuse terminals 4a, 4b. This allows the protective element 1 to provide spaces 10 above and below the fuse element between the insulating substrate 6 and the fuse terminals 4a, 4b.

[0058] [D3-W<2mm / W<5mm] In order to ensure that the distance D1 between the fuse terminal 4a and the side edge of the insulating substrate 6 and the distance D2 between the fuse terminal 4b and the side edge of the insulating substrate 6 are 1 mm or more, the protective element 1 preferably satisfies the following conditions. W<5mm D3-W<2mm W: Width of the insulating substrate 6 in the direction between the pair of fuse terminals 4a, 4b D3: Distance between a pair of fuse terminals 4a and 4b

[0059] [Fuse element] Next, a description will be given of the fuse element 3. The fuse element 3 is mounted between the fuse terminals 4a and 4b, and melts down due to heat generated by energization of the heating element 8 or self-heating (Joule heat) caused by the passage of a current exceeding the rated value, thereby cutting off the current path between the fuse terminals 4a and 4b.

[0060] 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 8 or when an overcurrent occurs. For example, in addition to SnAgCu-based Pb-free solder, a BiPbSn alloy, a BiPb alloy, a BiSn alloy, a SnPb alloy, a PbIn alloy, a ZnAl alloy, an InSn alloy, a PbAgSn alloy, etc. may be used.

[0061] The fuse element 3 may be a structure containing a high melting point metal and a low melting point metal. For example, as shown in Fig. 7, 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 to the fuse terminals 4a, 4b, the intermediate electrode 7, and the auxiliary electrode 18 via a bonding material such as a connection solder 13.

[0062] 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 fuse terminals 4a, 4b, the intermediate electrode 7, and the auxiliary electrode 18 are connected to the fuse element 3 by reflow.

[0063] 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 only a pair of opposing side surfaces are covered. 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. In addition to the coating structure, the fuse element 3 may 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.

[0064] The fuse element 3 has a coating structure or a laminated structure of the low melting point metal layer 26 and the high melting point metal layer 27, so that the fuse element 3 can maintain its shape and not melt even when the reflow temperature exceeds the melting temperature of the low melting point metal layer 26. Therefore, the fuse terminals 4a, 4b, the intermediate electrode 7, and the auxiliary electrode 18 can be efficiently connected to the fuse element 3 by reflow, and the fuse element 3 can be prevented from fluctuating in its 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 by reflow. Therefore, the protective element 1 can quickly melt the fuse element 3 by heat generated by the heating element 8 (FIG. 8).

[0065] 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 (Joule heat) and cuts off the current path between the fuse terminals 4a and 4b. At this time, as described above, the protective element 1 provides a space 10 between the fuse terminals 4a and 4b and the insulating substrate 6, and also provides spaces 11 above and below the fuse element 3 and the insulating substrate 6, making it difficult for the Joule heat of the fuse element 3 to be dissipated, and the fuse element 3 is heated over a wide area, dispersing and mitigating the explosive thermal shock when the fuse element 3 reaches its melting point and melts. Therefore, the protective element 1 can safely cut off even in the case of self-heating cutoff due to an overcurrent at a high voltage. In addition, it is possible to prevent sparks and tracking through molten debris and suppress deterioration of insulation.

[0066] In addition, when the fuse element 3 generates heat from the heating element 8 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 fuse element 3 is divided by the physical pulling action of the molten conductor 3a by the intermediate electrode 7 and the auxiliary electrode 18, so that the current path between the fuse terminals 4a, 4b can be quickly and reliably interrupted.

[0067] 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 8, 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 fuse terminals 4a, 4b.

[0068] 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.

[0069] Furthermore, the fuse element 3 can improve resistance (pulse resistance) to a surge in which an abnormally high voltage is instantaneously applied to an electric system in which the protective element 1 is incorporated. In other words, the fuse element 3 must not melt even when a current of, for example, 100 A flows for several msec. In this regard, since a large current that flows in an extremely short time flows through the surface layer of a conductor (skin effect), the fuse element 3 having a high melting point metal layer 27 such as Ag plating with low resistance as an outer layer can easily pass the current applied by a surge and can prevent melting due to self-heating. Therefore, the fuse element 3 can significantly improve resistance to a surge compared to a fuse made of a conventional solder alloy.

[0070] The fuse element 3 may be coated with flux (not shown) to prevent oxidation and improve wettability during melting.

[0071] [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. 9. 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.

[0072] 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 the 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.

[0073] 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.

[0074] 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. The control unit 44 operates by receiving power supply from the charging device 42, and controls the operation of the current control elements 43a, 43b so as to interrupt the current path when the battery stack 45 is overcharged or overdischarged according to the detection result by the detection circuit 47.

[0075] 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 .

[0076] 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.

[0077] 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.

[0078] 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. 10. That is, the protection element 1 has a fuse terminal 4a connected to the battery stack 45 side and a fuse terminal 4b connected to the positive terminal 40a side, whereby the fuse element 3 is connected in series to the charge / discharge path of the battery stack 45. In addition, the protection element 1 has a heating element 8 connected to the current control element 48 via the heating element power supply electrode 16 and the heating element terminal 15, and the heating element 8 connected to the battery stack 45. As a result, one end of the heating element 8 is connected to the fuse element 3 and one end of the battery stack 45 via the heating element electrode 17 and the intermediate electrode 7, and the other end is connected to the current control element 48 and the other end of the battery stack 45 via the heating element terminal 15. As a result, a power supply path to the heating element 8, the current supply of which is controlled by the current control element 48, is formed.

[0079] [Protection element operation] By mounting the protection element 1 on the external circuit board, the heating element 8 is connected to a current control element 48 and the like formed in the external circuit via the heating element terminal 15, 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 8. When a current flows from the battery stack 45, the heating element 8 starts to generate heat.

[0080] The heat of the heating element 8 is transferred to the fuse element 3 via the heating element electrode 17 and the intermediate electrode 7, and also transferred from the insulating substrate 6 to the fuse element 3 via the intermediate electrode 7 and auxiliary electrode 18, melting the fuse element 3. In the fuse element 3, the molten conductor 3a condenses on the intermediate electrode 7 and auxiliary electrode 18, and is melted between the fuse terminal 4a and the fuse terminal 4b (FIG. 8). This makes it possible to cut off the charge / discharge path of the battery pack 40.

[0081] Furthermore, even if 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 fuse terminals 4a and 4b of the protection device 1. This makes it possible to cut off the charge / discharge path of the battery pack 40.

[0082] 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.

[0083] When the fuse element 3 melts, the charge / discharge path of the battery stack 45 is cut off between the fuse terminals 4a and 4b. When the fuse element 3 melts, the power supply path to the heating element 8 is also cut off, and the heating element 8 stops generating heat.

[0084] 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.

[0085] [Variation 1] Next, modified examples of the protection element to which the present technology is applied will be described. In the following description, the same members as those of the protection element 1 described above will be given the same reference numerals, and their details may be omitted. As shown in FIG. 11, the protection element to which the present technology is applied may have a heating element 8 formed on the rear surface 6b of the insulating substrate 6. FIG. 11 is a cross-sectional view showing a protection element 50 in which a heating element 8 is formed on the rear surface 6b of the insulating substrate 6. FIG. 12 is a plan view showing the protection element 50 with the upper case 21 omitted. FIG. 13 is a view showing the insulating substrate 6 of the protection element 50, where (A) is a plan view and (B) is a bottom view.

[0086] The insulating substrate 6 has an intermediate electrode 7 and an auxiliary electrode 18 formed on the front surface 6a, and a heating element 8 and an insulating layer 9 formed on the back surface 6b. The insulating substrate 6 also has heating element power supply electrodes 16 formed on one side edge portions of the front surface 6a and the back surface 6b. The heating element power supply electrode 16a formed on the front surface 6a and the heating element power supply electrode 16b formed on the back surface 6b are continuous via castellations. The back surface heating element power supply electrode 16b is connected to the heating element 8. The front surface heating element power supply electrode 16a is connected to the heating element terminal 15.

[0087] Similarly, heating element electrodes 17 are formed on the other side edges of the front surface 6a and the back surface 6b, respectively. The heating element electrode 17a formed on the front surface 6a and the heating element electrode 17b formed on the back surface 6b are continuous via a conductive through hole. The back surface heating element electrode 17b is connected to the heating element 8. The front surface heating element electrode 17a is connected to the intermediate electrode 7.

[0088] [Forming process of fusing components] The fusing member 5 for the protective element 50 is formed by forming the front-side heating element power supply electrode 16a, the front-side heating element electrode 17a, and the auxiliary electrode 18 on the front surface 6a of the insulating substrate 6, which has half-through holes for castellation formed in advance on its side surface, using a known forming method such as screen printing, and then forming the intermediate electrode 7. The rear-side heating element power supply electrode 16b and the rear-side heating element electrode 17b are also formed on the rear surface 6b of the insulating substrate 6 using a known forming method such as screen printing. Next, the heating element 8 is formed, and the insulating layer 9 is laminated. After that, a through hole is formed by a drill or the like, and the heating element electrodes 17a and 17b are connected. Next, the castellation connecting the front-side and rear-side heating element power supply electrodes 16a and 16b and the through hole connecting the front-side and rear-side heating element electrodes 17a and 17b are electrically connected by plating or the like. The fusing member 5 is connected by the intermediate electrode 7, the auxiliary electrode 18, and the fuse element 3 with the connection solder 13. The fuse element 3 to which the fusing member 5 is connected is connected to fuse terminals 4a, 4b supported by a side edge 22a of the lower case 22 with connecting solder 13. In addition, the front-side heating element power supply electrode 16a of the insulating substrate 6 is connected by connecting solder 13 to a heating element terminal 15 supported by the side edge 22a of the lower case 22.

[0089] [Variation 2] Next, another modified example of the protection element to which the present technology is applied will be described. In the following description, the same components as those of the protection elements 1 and 50 described above will be given the same reference numerals, and their details may be omitted. In the protection element 60 shown in FIG. 14, a holding electrode 61 that holds the molten conductor 3a of the fuse element 3 when the fuse element 3 melts is formed on the back surface 6b of the insulating substrate 6. The holding electrode 61 is connected to the intermediate electrode 7 formed on the front surface 6a of the insulating substrate 6 by a through hole 62 that penetrates the insulating substrate 6.

[0090] Fig. 14 is a cross-sectional view showing a protection element 60 in which a holding electrode 61 is formed on the back surface 6b of an insulating substrate 6. Fig. 15 is a plan view showing the protection element 60 without the upper case 21. Fig. 16 is a diagram showing the insulating substrate 6 of the protection element 60, where (A) is a plan view and (B) is a bottom view.

[0091] The insulating substrate 6 has a heating element 8, an insulating layer 9 covering the heating element 8, an intermediate electrode 7 laminated on the insulating layer 9, and an auxiliary electrode 18 formed on a front surface 6a. The insulating substrate 6 also has a holding electrode 61 formed on a back surface 6b. The intermediate electrode 7 and the holding electrode 61 are connected to each other by a through hole 62 penetrating the insulating substrate 6.

[0092] 14, two heating elements 8 are formed in parallel on the front surface 6a of the insulating substrate 6. One end of each heating element 8 is connected to a heating element power supply electrode 16, and the other end is connected to a heating element electrode 17. Note that the protective element 60 may include one heating element 8 or three or more heating elements 8.

[0093] [Holding electrode] The holding electrode 61 formed on the back surface 6b of the insulating substrate 6 is formed at a position facing the intermediate electrode 7 formed at approximately the center of the front surface 6a, with the insulating substrate 6 interposed therebetween. The holding electrode 61 is also connected to the intermediate electrode 7 via a through hole 62 that penetrates from the surface of the holding electrode 61 to the surface of the intermediate electrode 7. As a result, the molten conductor 3a of the molten fuse element 3 is attracted toward the holding electrode 61 via the through hole 62.

[0094] The holding electrodes 61 can be formed by a known method such as screen printing using a known electrode material such as Ag, Cu, or an alloy material mainly containing Ag or Cu.

[0095] When the fuse element 3 melts, the through hole 62 draws in the molten conductor 3a of the fuse element 3 by capillary action, thereby reducing the volume of the molten conductor 3a held on the intermediate electrode 7. As a result, even if the fuse element 3 becomes larger due to a higher rating and higher capacity of the protective device 60, and the amount of melting increases, a large amount of molten conductor 3a can be held by the holding electrode 61, intermediate electrode 7, and auxiliary electrode 18, as shown in Fig. 17, and the fuse element 3 can be reliably melted.

[0096] The through holes 62 are formed in an area of ​​the insulating substrate 6 where the heating elements 8 are not formed. In the fusing member 5 shown in Figs. 14 to 16, the through holes 62 are formed in an area between the heating elements 8 arranged in parallel.

[0097] A conductive layer 64 is formed on the inner surface of the through hole 62. The conductive layer 64 is continuous with the holding electrode 61 and the intermediate electrode 7. This allows the holding electrode 61 and the intermediate electrode 7 to be electrically connected via the conductive layer 64. In addition, by forming the conductive layer 64, heat from the heating element 8 is also conducted to the holding electrode 61 via the intermediate electrode 7 and the through hole 62.

[0098] Furthermore, since the molten conductor 3a aggregates when the intermediate electrode 7 is melted, the intermediate electrode 7 is continuous with the conductive layer 64, which makes it easier to guide the molten conductor 3a into the through hole 62. The molten conductor 3a also spreads and is held by the holding electrode 61, which is continuous with the conductive layer 64 (FIG. 17). Therefore, more molten conductor 3a can be attracted and held by the through hole 62 and the holding electrode 61, which reduces the volume of the molten conductor 3a held by the intermediate electrode 7 and the auxiliary electrode 18, and ensures melting.

[0099] The conductive layer 64 is formed of, for example, any one of copper, silver, gold, iron, nickel, palladium, lead, and tin, or an alloy mainly composed of any one of these, and can be formed on the inner surface of the through hole 62 by a known method such as electrolytic plating or printing of a conductive paste. The conductive layer 64 may also be formed by inserting a plurality of metal wires or an assembly of conductive ribbons into the through hole 62.

[0100] The fusing member 5 may have a plurality of through holes 62. This increases the number of paths for attracting the molten conductor 3a of the fuse element 3, and allows a larger amount of the molten conductor 3a to be attracted quickly, thereby reducing the volume of the molten conductor 3a held by the intermediate electrode 7 and the auxiliary electrode 18.

[0101] [Forming process of fusing components] The fusing member 5 for the protective element 60 is formed by forming the heating element power supply electrode 16, the heating element electrode 17, and the auxiliary electrode 18 on the front surface 6a of the insulating substrate 6 using a known forming method such as screen printing, and then forming the heating element 8 and laminating the insulating layer 9. Next, the intermediate electrode 7 is formed. Also, the back surface 6b of the insulating substrate 6 is formed with a known forming method such as screen printing. Then, the through hole 62 is formed by a drill or the like, and the conductive layer 64 is formed by plating or the like to complete the fusing member 5. The intermediate electrode 7 and the auxiliary electrode 18 are connected to the fuse element 3 by the connection solder 13. The fuse element 3 to which the fusing member 5 is connected is connected to the fuse terminals 4a and 4b supported by the side edge portion 22a of the lower case 22 by the connection solder 13. Also, the heating element power supply electrode 16 of the insulating substrate 6 is connected to the heating element terminal 15 supported by the side edge portion 22a of the lower case 22 by the connection solder 13.

[0102] 18 is a circuit diagram of a protection element 60. In the fusing member 5 connected to the fuse element 3, one end of each heating element 8 formed on the surface 6a of the insulating substrate 6 is connected to the fuse element 3 via a heating element electrode 17 and an intermediate electrode 7. In addition, in the fusing member 5, a heating element power supply electrode 16 connected to the other end of each heating element 8 is connected to a heating element terminal 15 via a connection material such as a connection solder 13. As a result, in the fusing member 5, each heating element 8 is connected to a power source provided in an external circuit via the heating element terminal 15, and each heating element 8 is enabled to generate heat.

[0103] [Variation 3] Next, another modified example of the protection element to which the present technology is applied will be described. In the following description, the same members as those of the protection elements 1, 50, and 60 described above will be given the same reference numerals, and their details may be omitted. In the protection element 70 shown in FIG. 19, a heating element 8, an insulating layer 9 covering the heating element 8, and a holding electrode 61 for holding the molten conductor 3a of the fuse element 3 when the fuse element 3 is blown are formed on the back surface 6b of the insulating substrate 6. The holding electrode 61 is connected to the intermediate electrode 7 formed on the front surface 6a of the insulating substrate 6 by a through hole 62 penetrating the insulating substrate 6.

[0104] Fig. 19 is a cross-sectional view showing a protection element 70 in which a heating element 8, an insulating layer 9, and a holding electrode 61 are formed on the back surface 6b of an insulating substrate 6. Fig. 20 is a plan view showing the protection element 70 without the upper case 21. Fig. 21 is a view showing the insulating substrate 6 of the protection element 70, where (A) is a plan view and (B) is a bottom view.

[0105] The insulating substrate 6 has an intermediate electrode 7 and an auxiliary electrode 18 formed on the front surface 6a, and a heating element 8, an insulating layer 9, and a holding electrode 61 formed on the back surface 6b. The insulating substrate 6 also has heating element power supply electrodes 16 formed on one side edge portions of the front surface 6a and the back surface 6b. The heating element power supply electrode 16a formed on the front surface 6a and the heating element power supply electrode 16b formed on the back surface 6b are continuous via a castellation. The back surface heating element power supply electrode 16b is connected to the heating element 8. The front surface heating element power supply electrode 16a is connected to the heating element terminal 15.

[0106] Further, the insulating substrate 6 has a heating element electrode 17 formed on the other side edge of the rear surface 6b of the insulating substrate 6. The heating element electrode 17 is connected to the heating element 8 and is also connected to a holding electrode 61 laminated on the insulating layer 9.

[0107] The holding electrode 61 is laminated on the insulating layer 9, and is formed at a position facing the intermediate electrode 7 formed at approximately the center of the surface 6a, with the insulating substrate 6 interposed therebetween.

[0108] The through hole 62 is formed in an area of ​​the insulating substrate 6 where the heating elements 8 are not formed. In the fusing member 5 shown in Fig. 19, the through hole 62 is formed in an area between the parallel heating elements 8. Also, the through hole 62 has a conductive layer 64 formed on the inner surface thereof, which is continuous with the holding electrode 61 and the intermediate electrode 7.

[0109] As a result, the intermediate electrode 7 formed on the front surface 6 a of the insulating substrate 6 and the heating element 8 formed on the back surface 6 b are continuous via the heating element electrode 17 , the holding electrode 61 and the through hole 62 .

[0110] 19, two heating elements 8 are formed in parallel on the rear surface 6b of the insulating substrate 6. One end of each heating element 8 is connected to the rear surface heating element power supply electrode 16b, and the other end is connected to the heating element electrode 17. Note that the protective element 70 may also have one heating element 8 or three or more heating elements 8.

[0111] When the molten conductor 3a condenses on the intermediate electrode 7 when the fuse element 3 melts, the protective element 70 guides the molten conductor 3a into the through hole 62, where the molten conductor 3a spreads and is held by the holding electrode 61 continuous with the conductive layer 64 (see FIG. 22). Therefore, more molten conductor 3a can be attracted and held by the through hole 62 and the holding electrode 61, and the volume of the molten conductor 3a held by the intermediate electrode 7 and the auxiliary electrode 18 can be reduced, ensuring reliable meltdown.

[0112] It is also preferable to form a plurality of through holes 62 in the protective element 70. This increases the number of paths for attracting the molten conductor 3a of the fuse element 3, and allows a larger amount of the molten conductor 3a to be attracted quickly, thereby reducing the volume of the molten conductor 3a held by the intermediate electrode 7 and the auxiliary electrode 18.

[0113] [Variation 4] Next, another modified example of the protection element to which the present technology is applied will be described. In the following description, the same members as those of the protection elements 1, 50, 60, and 70 described above will be given the same reference numerals, and their details may be omitted. The protection element 80 shown in FIG. 23 is a protection element 60 having a heating element 8 provided on the surface 6a of an insulating substrate 6, and a fusing member 5 associated with the protection element 60 is connected to one surface of the fuse element 3 and the other surface opposite to the one surface. That is, in the protection element 80, the fuse element 3 is sandwiched between a plurality of fusing members 5.

[0114] Fig. 23 is a cross-sectional view showing a protection element 80 in which a fusing member 5 having a heating element 8 formed on a front surface 6a of an insulating substrate 6 is connected to one and the other surfaces of a fuse element 3. Fig. 24 is a plan view showing the protection element 80 with the upper case 21 omitted.

[0115] 25 is a circuit diagram of a protection element 80. In each fusing member 5 connected to one surface and the other surface of the fuse element 3, one end of the heating element 8 formed on the surface 6a of each insulating substrate 6 is connected to the fuse element 3 via a heating element electrode 17 and an intermediate electrode 7. In addition, each fusing member 5 faces each heating element power supply electrode 16 connected to the other end of the heating element 8, and is connected to each heating element terminal 15 via a connection material such as a connection solder 13. As a result, each fusing member 5 is connected to a power source for generating heat from the heating element 8 provided in an external circuit via the heating element terminal 15.

[0116] 26, when the protective element 80 melts the fuse element 3 due to heat generated by the heating element 8, the heating elements 8 of the fusing members 5, 5 connected to both sides of the fuse element 3 generate heat, heating the fuse element 3 from both sides. Therefore, the protective element 80 can quickly heat and melt the fuse element 3 even when the cross-sectional area of ​​the fuse element 3 is increased to accommodate high current applications.

[0117] Furthermore, the protective element 80 draws the molten conductor 3a from both sides of the fuse element 3 into each through-hole 62 formed in each fusing member 5 and holds it with the holding electrode 61. Therefore, even if a large amount of molten conductor 3a is generated by increasing the cross-sectional area of ​​the fuse element 3 to accommodate high-current applications, the protective element 80 can draw in the molten conductor 3a using the multiple fusing members 5 and reliably melt the fuse element 3. Furthermore, by drawing in the molten conductor 3a using the multiple fusing members 5, the protective element 80 can more quickly melt the fuse element 3.

[0118] The protective element 80 can quickly blow the fuse element 3 even when a coating structure in which a low melting point metal constituting the inner layer is coated with a high melting point metal or a laminated structure of a low melting point metal and a high melting point metal is used as the fuse element 3. That is, the fuse element 3 coated or laminated with a high melting point metal takes time to heat up to a temperature at which the high melting point metal melts even when the heating element 8 generates heat. Here, the protective element 80 includes a plurality of fusing members 5, and can heat the heating elements 8 simultaneously to quickly heat the high melting point metal to its melting temperature. Therefore, according to the protective element 80, the thickness of the high melting point metal layer constituting the outer layer can be increased, and the fast blowing characteristic can be maintained while achieving a higher rating.

[0119] 23, the protective element 80 is preferably connected to the fuse element 3 with a pair of fusing members 5, 5 facing each other. This allows the protective element 80 to heat the same location of the fuse element 3 from both sides simultaneously with the pair of fusing members 5, 5 and to suck in the molten conductor 3a, enabling the fuse element 3 to be heated and blown more quickly.

[0120] Furthermore, in the protective element 80, it is preferable that the auxiliary electrodes 18 formed on the insulating substrates 6 of the pair of fusing members 5, 5 face each other via the fuse element 3. This allows the pair of fusing members 5, 5 to be symmetrically connected, which prevents the load applied from the fusing members 5 to the fuse element 3 from becoming unbalanced during reflow mounting or heating of the fuse element 3, and improves resistance to deformation of the fuse element 3 and connection misalignment of the fusing members 5.

[0121] It is preferable to form heating elements 8 on both sides of through hole 62 in order to heat auxiliary electrode 18 and intermediate electrode 7 and to aggregate and attract a larger amount of molten conductor 3a.

[0122] [Variation 5] Next, another modified example of the protection element to which the present technology is applied will be described. In the following description, the same members as those of the protection elements 1, 50, 60, 70, and 80 described above will be given the same reference numerals, and their details may be omitted. The protection element 90 shown in FIG. 27 is a protection element 70 having a heating element 8 provided on the rear surface 6b of the insulating substrate 6, and a fusing member 5 connected to one surface and the other surface of the fuse element 3. That is, in the protection element 90, the fuse element 3 is sandwiched between a plurality of fusing members 5.

[0123] Fig. 27 is a cross-sectional view showing a protection element 90 in which a fusing member 5 having a heating element 8 formed on the rear surface 6b of an insulating substrate 6 is connected to one surface and the other surface of a fuse element 3. Fig. 28 is a plan view showing the protection element 90 with the upper case 21 omitted.

[0124] The protective element 90 has a circuit configuration similar to that of the protective element 80 shown in Fig. 25. In each fusing member 5 connected to one surface and the other surface of the fuse element 3, one end of the heating element 8 formed on the back surface 6b of each insulating substrate 6 is connected to the fuse element 3 via the intermediate electrode 7 that is continuous with the heating element electrode 17, the holding electrode 61, and the through hole 62. In addition, each fusing member 5 faces the front side heating element power supply electrode 16a connected to the other end of the heating element 8, and is connected to the heating element terminal 15 via a connection material such as a connection solder 13. As a result, each fusing member 5 is connected to a power source for generating heat from the heating element 8 provided in the external circuit via the heating element terminal 15.

[0125] In the protective element 90, the melting operation and effect due to heat generation from the heating element 8 are similar to those of the protective element 80 described above, and heat is applied from both sides of the fuse element 3. Also, as shown in Fig. 29, the protective element 90, like the protective element 80, draws the molten conductors 3a from both sides of the fuse element 3 into the through holes 62 formed in each fusing member 5 and holds them by the holding electrodes 61.

[0126] Furthermore, the protective element 90 can more quickly melt the fuse element 3 by attracting the molten conductor 3a with the multiple fusing members 5. Furthermore, the protective element 90 includes multiple fusing members 5, and can heat the heating elements 8 simultaneously to quickly heat the high-melting point metal to its melting temperature. Therefore, according to the protective element 90, the thickness of the high-melting point metal layer constituting the outer layer can be increased, and the fast-melting characteristic can be maintained while achieving a higher rating.

[0127] 27, in the protection element 90, it is preferable that the pair of fusing members 5, 5 are connected to the fuse element 3 facing each other. It is also preferable that the auxiliary electrodes 18 formed on the insulating substrates 6 of the pair of fusing members 5, 5 face each other via the fuse element 3 in the protection element 90.

[0128] It is preferable to form heating elements 8 on both sides of through hole 62 in order to heat auxiliary electrode 18 and intermediate electrode 7 and to aggregate and attract a larger amount of molten conductor 3a. [Explanation of symbols]

[0129] 1 protection element, 2 case, 3 fuse element, 4a, 4b fuse terminal, 5 fusing member, 6 insulating substrate, 6a front surface, 6b rear surface, 7 intermediate electrode, 8 heating element, 9 insulating layer, 10 space, 11 space, 13 connection solder, 14 screw hole, 15 heating element terminal, 16 heating element power supply electrode, 17 heating element electrode, 18 auxiliary electrode, 21 upper case, 22 lower case, 22a side edge portion, 22b hollow portion, 23 mating recess, 24 mating protrusion, 25 adhesive, 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, 60 Protective element, 61 holding electrode, 62 through hole, 64 conductive layer, 70 protective element, 80 protective element, 90 protective element

Claims

1. The case and The fuse element housed in the above case, A pair of fuse terminals are supported on the side of the case, spaced apart in the direction of current flow of the fuse element, and connected to the fuse element. The fuse element is connected to at least one side of the fuse element between the pair of fuse terminals and comprises a cutting member that melts the fuse element, The above-mentioned fuse cutting member comprises an insulating substrate and an intermediate electrode provided on the surface of the insulating substrate that is in contact with the fuse element and connected to the fuse element. Between the insulating substrate and at least one of the pair of fuse terminals, there is space above and below the fuse element. In the region where the fuse element and the insulating substrate overlap, there are spaces above and below the fuse element and the insulating substrate. Protective element.

2. The protective element according to claim 1, wherein the fuse cutting member comprises a heating element formed on the insulating substrate that melts the fuse element by generating heat, and an insulating layer covering the heating element.

3. The protective element according to claim 1 or 2, wherein the distance D3 between the pair of fuse terminals is 7 mm or more in a cross-sectional view.

4. The protective element according to claim 1 or 2, wherein, in a cross-sectional view, the distance D1 between one of the fuse terminals and the side edge of the insulating substrate facing the one of the fuse terminals is 1 mm or more.

5. The protective element according to claim 4, wherein, in a cross-sectional view, the distance D2 between the other fuse terminal and the side edge of the insulating substrate facing the other fuse terminal is 1 mm or more.

6. The protective element according to claim 1 or 2, wherein, in a cross-sectional view, the width W of the insulating substrate in the direction between the pair of fuse terminals is smaller than the distance D3 between the pair of fuse terminals.

7. The protective element according to claim 6, satisfying the following conditions. W < 5 mm D3-W < 2mm

8. The protective element according to claim 2, wherein the heating element is provided on the surface of the insulating substrate or on the back surface opposite to the surface.

9. The above insulating substrate has a holding electrode provided on the back surface opposite to the above surface, The protective element according to claim 1 or 2, wherein the intermediate electrode and the holding electrode are connected by a through hole that penetrates the insulating substrate.

10. The system comprises one or more battery cells and a protective element connected to the charge / discharge path of the battery cells and blocking the charge / discharge path. The protective element is the protective element described in claim 1 or 2 above. Battery pack.

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