Protection elements and battery packs

Abstract

To provide a protection element which incorporates a heating element therein, deals with high voltage and heavy current, and blocks a current path more safely and quickly without causing damage in the element.SOLUTION: A protection element includes: a fuse element 2: and a fusing member 3. The fusing member 3 has: an insulation substrate 4; a heating element 5; an insulation layer 6 which covers the heating element; a heating element extraction electrode 7 which is overlapped with the heating element 5 through the insulation layer 6; a heat radiation part 8 which is formed at an area, which is located at the surface 4a side of the insulation substrate 4 and overlaps with at least the heating element 5, and electrically independent from the heating element extraction electrode 7; a holding electrode 10 which is formed on a rear surface 4b of the insulation substrate 4 and holds a fused conductor 2a of the fuse element 2; and a through hole 11 which allows the heating element extraction electrode 7 and the holding element 10 to be continuous with each other. The fuse element 2 is connected to the holding electrode 10.SELECTED DRAWING: Figure 2

Description

[Technical Field]

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

[0002] Most rechargeable secondary batteries are manufactured into battery packs and provided to users. To ensure the safety of users and electronic devices, lithium-ion secondary batteries, which have particularly high weight energy density, generally incorporate several protection circuits, such as overcharge protection and overdischarge protection, into the battery pack, and have the function of shutting down the output of the battery pack under specified conditions.

[0003] In many electronic devices using lithium-ion secondary batteries, a built-in FET switch in the battery pack is used to turn the output on and off to protect the battery pack from overcharge or overdischarge. However, the battery pack and electronic devices must be protected from accidents such as fire if the FET switch is short-circuited for some reason, if a lightning surge or other event causes a momentary large current to flow, or if the output voltage of the battery cell drops abnormally due to its lifespan or, conversely, if an excessively large voltage is output. Therefore, to safely shut off the battery cell output in any of these possible abnormal conditions, a protective element consisting of a fuse element that can interrupt the current path in response to an external signal is used.

[0004] A protective element of a protection circuit for such 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 the 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 used in applications requiring larger currents, such as power tools such as electric screwdrivers, transportation equipment such as hybrid cars, electric vehicles, and electrically assisted bicycles, and drones. In these applications, large currents exceeding several tens of amperes to 100 amperes may flow, particularly during startup. There is a demand for protective elements that can handle such large current capacities.

[0006] In order to realize a protective element that can handle such a large current, a protective element has been proposed in which a soluble 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 soluble conductor.

[0007] 39 is a cross-sectional view showing an example of the configuration of a conventional protection element. The protection element 100 shown in Fig. 39 includes a fuse element 101 and a pair of fusing members 102 that blow the fuse element 101.

[0008] 40 is a diagram showing a fusing member, where (A) is a plan view showing the front side of an insulating substrate on which a heating element is provided, and (B) is a bottom view showing the back side of the insulating substrate that contacts the fuse element 101. Each fusing member 102 has an insulating substrate 103, a heating element 104 formed on the front side of the insulating substrate 103, an insulating layer 105 that covers the heating element 104, a heating element lead electrode 106 that is connected to the heating element 104 and overlaps the heating element 104 via the insulating layer 105, a holding electrode 107 that is formed on the back side of the insulating substrate 103 and holds the molten conductor of the fuse element 101 when the fuse element 101 melts, and a through hole 108 that penetrates the insulating substrate 103 and connects the heating element lead electrode 106 and the holding electrode 107.

[0009] The heating element 104 is connected to an external circuit equipped with a power source via a heating element power supply electrode 110, and can be supplied with power from the external circuit.

[0010] The fuse element 101 is connected to first and second electrode terminals 111 and 112, which are connected to an external circuit, by a bonding material such as connection solder 114. The fuse element 101 is also connected to the holding electrode 107 and an auxiliary electrode 109 formed on the back surface of the insulating substrate 103 by a bonding material such as connection solder 114.

[0011] When the heating element 104 is energized and generates heat, the heat of the fusing member 102 melts the fuse element 101, and the resulting molten conductor 101a is attracted to the heating element lead electrode 106 side through the through hole 108. As a result, the fuse element 101 is fused between the holding electrode 107 and the auxiliary electrode 109, and the electrical continuity between the first electrode terminal 111 and the second electrode terminal 112 is interrupted. [Prior art documents] [Patent documents]

[0012] [Patent Document 1] Japanese Patent Publication No. 2020-173965 Summary of the Invention [Problem to be solved by the invention]

[0013] In a conventional structure such as the protective element 100 shown in FIG. 39, when used in a protective circuit for high-voltage, high-current applications such as electric vehicles, a fuse element 101 with a large cross-sectional area that can withstand large currents is used, and when the protective element 100 is activated, a high voltage is applied to the heating element 104 to quickly melt the fuse element 101, generating high heat.

[0014] As a result, a temperature difference occurs on insulating substrate 103 due to a difference in thermal conductivity between the region with heater element lead electrode 106 and the region without heater element lead electrode 106, and stress may damage insulating substrate 103 or heater element 104. That is, as shown in FIG. 42(A), in the region where heater element lead electrode 106 is formed, heat from heater element 104 is dispersed and transferred to insulating substrate 103 and heater element lead electrode 106, so that insulating substrate 103 does not overheat locally. On the other hand, in region R where heater element lead electrode 106 is not formed, heat from heater element 104 is transferred only to insulating substrate 103, so that insulating substrate 103 is overheated compared to the region where heater element lead electrode 106 is formed. As a result, a bias in the heat distribution on insulating substrate 103 generates stress, which may damage insulating substrate 103 or heater element 104.

[0015] This may result in a longer time until fuse element 107 is blown, making it impossible to quickly and safely cut off the current path, and may even cause heating element 104 to stop generating heat before the fuse element is blown, as shown in Figures 42(B) and 41. Figure 43(A) is a cross-sectional view of fusing member 102 taken along line A-A' in Figures 42(A) and (B). Figure 43(B) is a cross-sectional view of fusing member 102 taken along line B-B' in Figures 42(A) and (B).

[0016] The risk that such damage to the insulating substrate 103 or heating element 104 will cause the fuse element 101 to remain unmelted and hinder current interruption increases as the fuse element 101 becomes larger due to higher voltages and currents, as the current rating increases and the electric field strength becomes stronger, and as the insulating layer 105 becomes thinner due to the miniaturization of the protection device 100.

[0017] Therefore, there is a demand for a protective element with a built-in heating element that can handle higher voltages and currents, and that operates more safely and quickly without causing damage inside the element.

[0018] Therefore, the present technology aims to provide a protective element that can prevent damage inside the element even when a high voltage is applied and can safely and quickly cut off the current path, and a battery pack using the same. [Means for solving the problem]

[0019] In order to solve the above-described problems, a protection element according to the present technology includes a fuse element and a fusing member that fuses the fuse element, the fusing member including an insulating substrate, a heating element formed on a surface side of the insulating substrate, an insulating layer that covers the heating element, a heating element lead electrode that is connected to the heating element and overlaps the heating element via the insulating layer, a heat dissipation portion that is formed on the surface side of the insulating substrate in at least a region that overlaps with the heating element and is electrically independent from the heating element lead electrode, a holding electrode that is formed on a back surface opposite to the surface of the insulating substrate and that holds a molten conductor of the fuse element when the fuse element fuses, and a through hole that connects the heating element lead electrode and the holding electrode, and the fuse element is connected to the holding electrode.

[0020] a heat sink formed on the front surface of the insulating substrate; an insulating layer covering the heating element; a heating element lead electrode connected to the heating element and overlapping the heating element via the insulating layer; a heat dissipation portion formed on at least a region overlapping the heating element on the front surface of the insulating substrate and electrically independent from the heating element lead electrode; a holding electrode formed on the back surface of the insulating substrate opposite to the front surface and holding a molten conductor of the fuse element when the fuse element is blown; and a through hole connecting the heating element lead electrode and the holding electrode,

[0021] Furthermore, a protection element according to the present technology includes a fuse element and a fusing member that fuses the fuse element, the fusing member including an insulating substrate, a heating element formed on a surface side of the insulating substrate, an insulating layer that covers the heating element, a heating element lead electrode that is connected to the heating element and overlaps the heating element via the insulating layer, a heat dissipation portion that is formed on the surface side of the insulating substrate in at least a region that overlaps with the heating element and is electrically independent from the heating element lead electrode, and a first electrode and a second electrode that are formed on the surface of the insulating substrate and are connected to an external circuit, and the fuse element is connected to the first electrode, the second electrode, and the heating element lead electrode that is provided between the first electrode and the second electrode.

[0022] In addition, a protection element according to the present technology includes a fuse element and a fusing member that fuses the fuse element, the fusing member including an insulating substrate, a heating element formed on a front surface side of the insulating substrate, an insulating layer that covers the heating element, a heating element lead electrode that is formed on a rear surface side of the insulating substrate so as to overlap with the heating element and is connected to the heating element, a heat dissipation portion that is formed on the rear surface side of the insulating substrate in at least a region that overlaps with the heating element and is electrically independent from the heating element lead electrode, and a first electrode and a second electrode that are formed on the rear surface of the insulating substrate and are connected to an external circuit, and the fuse element is connected to the first electrode, the second electrode, and the heating element lead electrode.

[0023] a heat sink formed on the front surface of the insulating substrate in at least an area overlapping with the heating elements and electrically independent from the heating element lead electrode; first and second electrodes formed on the rear surface of the insulating substrate and connected to an external circuit; a holding electrode provided between the first electrode and the second electrode on the rear surface of the insulating substrate; and a through hole penetrating an area between the plurality of heating elements of the insulating substrate and connecting the heating element lead electrode and the holding electrode; and the fuse element is connected to the first electrode, the second electrode, and the holding electrode.

[0024] 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 any of the protection elements described above. [Effects of the Invention]

[0025] According to this technology, since a heat dissipation portion is formed at least in the area overlapping with the heating element, uneven heat distribution on the insulating substrate due to heat generated by the heating element is reduced, which prevents damage to the insulating substrate and the heating element due to stress caused by uneven heat distribution and allows the fuse element to melt safely and quickly even when a high voltage is applied to the heating element. [Brief explanation of the drawings]

[0026] [Figure 1] FIG. 1 is a plan view of a protection element to which the present technology is applied. [Figure 2] FIG. 2 is a cross-sectional view of the protection element to which the present technology is applied, taken along the line DD' shown in FIG. [Figure 3]3A and 3B are diagrams showing a fusing member, in which (A) is a plan view showing the front surface of an insulating substrate, and (B) is a bottom view showing the back surface of the insulating substrate. [Figure 4] FIG. 4 is a plan view showing a fusing member in which the base of the heating element lead electrode is formed beyond the insulating layer to both side edges of the insulating substrate. [Figure 5] FIG. 5 shows a fusing member provided with an insulating coating layer that covers a heat dissipation portion, where (A) is a plan view showing the surface of an insulating substrate, and (B) is a cross-sectional view. [Figure 6] FIG. 6 is a plan view showing a fusing member in which a heat dissipation portion is provided over as wide an area as possible. [Figure 7] 7A and 7B are diagrams showing a state in which a fuse element in a protection device to which the present technology is applied has melted, where (A) is a cross-sectional view taken along line A-A' in FIG. 8, and (B) is a cross-sectional view taken along line B-B' in FIG. 8. [Figure 8] FIG. 8 is a diagram showing a state in which a fuse element in a protection device to which the present technology is applied has been blown, where (A) is a plan view and (B) is a bottom view. [Figure 9] FIG. 9 is a circuit diagram of a protection element to which the present technology is applied. [Figure 10] FIG. 10 is a cross-sectional view showing a state in which a fuse element in a protection device to which the present technology is applied has been blown. [Figure 11] FIG. 11 is a cross-sectional view of a fuse element. [Figure 12] FIG. 12 is a plan view showing a configuration in which a fusing member is connected to one surface of a fuse element and a fusing member is connected to the other surface of the fuse element. [Figure 13] FIG. 13 is a circuit diagram showing an example of the configuration of a battery pack. [Figure 14] FIG. 14 is a cross-sectional view showing a modified example of a protective element in which a protrusion is provided on the case. [Figure 15] FIG. 15 is a plan view showing a modified example of a protective element in which a protrusion is provided on the case. [Figure 16] FIG. 16 is a cross-sectional view showing a modified example of a protective element in which a heat dissipation element is provided on a heat dissipation portion. [Figure 17]FIG. 17 is a plan view showing a modified example of a protective element in which a heat dissipation element is provided on a heat dissipation portion. [Figure 18] FIG. 18 is a perspective view showing the appearance of a fusing member provided with a heat sink as a heat dissipation element on a heat dissipation portion. [Figure 19] FIG. 19 is a cross-sectional view showing a modified example of a protection element to which the present technology is applied. [Figure 20] 20A and 20B are diagrams showing the fusing member of the protection element according to the modified example shown in FIG. 19, where (A) is a plan view and (B) is a bottom view. [Figure 21] 21A to 21C are diagrams showing a modified example of a protection element to which the present technology is applied, in which (A) is a plan view, (B) is a cross-sectional view, and (C) is a bottom view. [Figure 22] 22A and 22B are diagrams showing a state in which the fuse element of the protection element shown in FIG. 21 has been blown, with (A) being a plan view and (B) being a cross-sectional view. [Figure 23] FIG. 23 is a plan view showing a modification of the protective element shown in FIG. 21 in which the heat dissipation portion is formed only on the insulating layer 6. In FIG. [Figure 24] FIG. 24 is a plan view showing a modification of the protective element shown in FIG. 21 in which the heat dissipation portion is formed over as wide an area as possible in which no other electrodes are formed. [Figure 25] FIG. 25 is a circuit diagram of the protection element shown in FIG. [Figure 26] 26A to 26C are diagrams showing a modified example of a protection element to which the present technology is applied, in which (A) is a plan view, (B) is a cross-sectional view, and (C) is a bottom view. [Figure 27] 27A and 27B are diagrams showing a modified example of the protection element shown in FIG. 26 in which an insulating coating layer is provided to cover the heat dissipation portion, where (A) is a plan view and (B) is a cross-sectional view. [Figure 28] FIG. 28 is a plan view showing a modification of the protective element shown in FIG. 26 in which the heat dissipation portion is formed over as wide an area as possible in which no other electrodes are formed. [Figure 29] FIG. 29 is a plan view showing a modification in which an insulating coating layer is provided to cover the heat dissipation portion in the protection element shown in FIG. [Figure 30]30A and 30B are diagrams showing a modified example of the protection element shown in FIG. 26 in which a second heat dissipation portion is provided, where (A) is a cross-sectional view and (B) is a plan view. [Figure 31] FIG. 31 is a plan view showing a fusing member in which an attracting electrode is not formed and the heat dissipation portion is made as large as possible. [Figure 32] FIG. 32 is a diagram showing a modified example of a protection element to which the present technology is applied, where (A) is a plan view and (B) is a bottom view. [Figure 33] 33(A) is a cross-sectional view taken along line AA' in FIG. 32(A), and FIG. 33(B) is a cross-sectional view taken along line BB' in FIG. 32(A). [Figure 34] FIG. 34 is a circuit diagram of the protection element shown in FIG. [Figure 35] 35A and 35B are diagrams showing a state in which the fuse element of the protection element shown in FIG. 32 has been blown, with (A) being a plan view and (B) being a bottom view. [Figure 36] 36(A) is a cross-sectional view taken along line AA' in FIG. 35, and FIG. 36(B) is a cross-sectional view taken along line BB' in FIG. [Figure 37] FIG. 37 is a cross-sectional view showing a modified example of a protection element to which the present technology is applied. [Figure 38] 38A and 38B are diagrams showing the protective element shown in FIG. 37, where (A) is a plan view and (B) is a bottom view. [Figure 39] FIG. 39 is a cross-sectional view showing an example of the configuration of a conventional protection element. [Figure 40] Figure 40 shows a fusing member, where (A) is a plan view showing the front surface side of the insulating substrate on which the heating element is provided, and (B) is a bottom view showing the back surface side of the insulating substrate that contacts the fuse element. [Figure 41] FIG. 41 is a cross-sectional view showing a state in which the fuse element of the protection element shown in FIG. 40 is partially uncut. [Figure 42] 42A and 42B are diagrams showing a state in which the fuse element of the protection element shown in FIG. 40 is not cut, where (A) is a plan view and (B) is a bottom view. [Figure 43]43(A) is a cross-sectional view of the fusing member taken along line AA' in FIGS. 42(A) and (B), and FIG. 43(B) is a cross-sectional view of the fusing member taken along line BB' in FIGS. 42(A) and (B). DETAILED DESCRIPTION OF THE INVENTION

[0027] A protective element to which the present technology is applied and a battery pack using the same will be described in detail below with reference to the drawings. It should be noted that 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 those of the actual devices. Specific dimensions should be determined with reference to the following description. It should be noted that the drawings may also include portions in which the dimensional relationships and ratios differ.

[0028] [Protection element] 1, 2, and 3, a protection element 1 to which the present invention is applied includes a fuse element 2 and a fusing member 3 that fuses the fuse element 2. FIG. 1 is a plan view of the protection element 1, FIG. 2 is a cross-sectional view of the protection element 1 taken along the line D-D' shown in FIG. 1, and FIG. 3 is a diagram showing the fusing member 3, in which (A) is a plan view showing the front surface 4a of an insulating substrate 4 and (B) is a bottom view showing the back surface 4b of the insulating substrate 4.

[0029] The fusing member 3 includes an insulating substrate 4, a heating element 5 formed on the surface 4a side of the insulating substrate 4, an insulating layer 6 covering the heating element 5, a heating element extraction electrode 7 connected to the heating element 5 and overlapping with the heating element 5 via the insulating layer 6, and a heat dissipation section 8 formed on the surface 4a side of the insulating substrate 4 in at least the area overlapping with the heating element 5 and electrically independent from the heating element extraction electrode 7.

[0030] In addition, a holding electrode 10 is formed on the back surface 4b opposite to the front surface 4a of the insulating substrate 4, which holds the molten conductor 2a of the fuse element 2 when the fuse element 2 melts, and the heating element extraction electrode 7 and the holding electrode 10 are connected by a through hole 11 that penetrates from the insulating substrate 4 to the heating element extraction electrode 7.

[0031] The fuse element 2 is connected to the holding electrode 10 by a bonding material such as connection solder 9. The fuse element 2 is also connected to first and second electrode terminals 21 and 22, both ends of which are connected to an external circuit, by a bonding material such as connection solder 9.

[0032] According to this protective element 1, the heat dissipation portion 8 is formed at least in the region overlapping with the heating element 5, which reduces uneven heat distribution on the insulating substrate 4 due to heat generated by the heating element 5. This prevents damage to the insulating substrate 4 and the heating element 5 due to stress caused by uneven heat distribution, and allows the fuse element 2 to blow safely and quickly even when a high voltage is applied to the heating element 5.

[0033] The components of the fusing member 3 of the protection device 1 and the fuse element 2 will be described in detail below.

[0034] [Fusing material] [Insulating substrate] The fusing member 3 includes an insulating substrate 4. The insulating substrate 4 is formed of an insulating material such as alumina, glass ceramics, mullite, or zirconia. Alternatively, the insulating substrate 4 may be made of a material used for printed wiring boards, such as a glass epoxy board or a phenol board. A heating element 5 is formed on a surface 4a of the insulating substrate 4.

[0035] In the present invention, as shown in Fig. 3(A), the surface of the insulating substrate 4 on which the heating element 5 is formed is referred to as the front surface 4a, and as shown in Fig. 3(B), the surface opposite to the front surface 4a is referred to as the back surface 4b. The insulating substrate 4 is also formed with through holes 11 that connect the heating element lead electrode 7 (described later) formed on the front surface 4a with the holding electrode 10 (described later) formed on the back surface 4b.

[0036] [Heater] Heating element 5 is an electrically 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. Heating element 5 can be formed by mixing powder of these alloys, compositions, or compounds with a resin binder or the like to form a paste, forming a pattern on insulating substrate 4 using a screen printing technique, and firing the paste.

[0037] In the protection element 1 shown in Fig. 2, two heating elements 5 are formed in parallel on the front surface 4a of the insulating substrate 4. One end of each heating element 5 is connected to a heating element power supply electrode 12, and the other end is connected to a heating element electrode 14. The heating element power supply electrode 12 is an electrode connected to one end of the heating element 5 and serves as a power supply terminal for the heating element 5, and is continuous with an external connection electrode 12a formed on the back surface 4b of the insulating substrate 4 via a castellation. Each heating element 5 is covered with an insulating layer 6, and a heating element lead electrode 7 formed on the insulating layer 6 is superimposed on it.

[0038] The external connection electrode 12a is connected to a third electrode terminal 23 connected to an external circuit by a bonding material such as connection solder 9, thereby being connected to a power supply provided in the external circuit and being able to supply power to the heating element 5. In addition, the heating element electrode 14 is connected to a heating element lead electrode 7 described later.

[0039] The heating element power supply electrodes 12 and the heating element electrodes 14 are each formed of a conductive pattern of Ag, Cu, or the like. Preferably, the surfaces of the heating element power supply electrodes 12 and the heating element electrodes 14 are coated with a film such as Ni / Au plating, Ni / Pd plating, or Ni / Pd / Au plating by a known method such as plating. This allows the protection element 1 to prevent oxidation of the heating element power supply electrodes 12 and the heating element electrodes 14 and to prevent fluctuations in rating due to an increase in conduction resistance.

[0040] It is preferable that the heater power supply electrode 12 be provided with a restriction wall (not shown) to prevent the connection solder connecting the external connection electrode 12a and the third electrode terminal 23 from melting during reflow mounting or the like, creeping up onto the heater power supply electrode 12 via castellations, and spreading over the heater power supply electrode 12. The restriction wall can be formed using an insulating material that is not wettable by solder, such as glass, solder resist, or an insulating adhesive, and can be formed on the heater power supply electrode 12 by printing or the like. The provision of the restriction wall prevents the molten connection solder 9 from spreading over the heater power supply electrode 12, thereby maintaining the connectivity between the protection element 1 and the external circuit board.

[0041] The insulating layer 6 is formed of, for example, a glass layer, and is provided to protect and insulate the heating element 5. The insulating layer 6 is formed to be thin, for example, 10 to 40 μm in thickness. The insulating layer 6 may also be formed between the surface 4 a of the insulating substrate 4 and the heating element 5.

[0042] [Heater element extraction electrode] The heater lead electrode 7 is formed of a conductive pattern of Ag, Cu, or the like, similar to the heater power supply electrode 12 and the heater electrode 14. The surface of the heater lead electrode 7 is preferably coated with a film such as Ni / Au plating, Ni / Pd plating, or Ni / Pd / Au plating by a known method such as plating.

[0043] The heating element extraction electrode 7 has one end connected to the heating element electrode 14, is formed on the insulating layer 6, and overlaps the heating element 5 with the insulating layer 6 interposed therebetween. The heating element extraction electrode 7 has a tip portion 7a that extends between the two heating elements 5, which is an area where no heating elements 5 are formed, and a base portion 7b that overlaps the two heating elements 5 and is connected to the heating element electrode 14. When the direction perpendicular to the current-carrying direction of the heating elements 5 is taken as the width direction, the heating element extraction electrode 7 has a wide portion that overlaps the two heating elements 5 as the base portion 7b, and a narrow portion that protrudes from the base portion 7b and extends into the area between the two heating elements 5 as the tip portion 7a.

[0044] The heater lead electrode 7 is provided with a through hole 11 and is electrically and thermally connected to a holding electrode 10 formed on the rear surface 4b of the insulating substrate 4. As a result, heat from the heater 5 is transferred to the fuse element 2 via the heater lead electrode 7, through hole 11, and holding electrode 10, melting the fuse element 2. In addition, the molten conductor 2a of the fuse element 2 is attracted to the through hole 11 and held on the heater lead electrode 7.

[0045] 4, the base 7b of the heater lead electrode 7 may be formed beyond the insulating layer 6 to reach both side edges of the insulating substrate 4. The larger the area of ​​the heater lead electrode 7, the more the heat from the heater 5 is diffused onto the insulating substrate 4, making it easier to eliminate uneven heat distribution on the insulating substrate 4.

[0046] [Heat dissipation part] 3(A), a heat dissipation section 8 that is electrically independent from the heat generating element lead electrode 7 is formed on the front surface 4a side of the insulating substrate 4, at least in the region that overlaps with the heat generating element 5. The heat dissipation section 8 is a section that absorbs heat generated by the heat generating element 5, and is provided to reduce uneven heat distribution on the insulating substrate 4.

[0047] The heat dissipation section 8 can suppress damage (thermal shock cracks) to the insulating substrate 4 and the heating element 5 due to heat concentration when the heating element 5 generates heat. That is, in the fusing member 3, the heat from the heating element 5 is transferred to the insulating substrate 4, the heating element lead electrode 7, and the heat dissipation section 8. If the heat dissipation section 8 is not formed, the heat from the heating element 5 is absorbed by the heating element lead electrode 7 along with the insulating substrate 4 in the region where the heating element lead electrode 7 is formed, but is concentrated on the insulating substrate 4 in the region where the heating element lead electrode 7 is not formed. This causes a bias in the heat distribution on the insulating substrate 4, which can cause cracks due to thermal shock in the region where the heat is concentrated. Furthermore, the heating element 5 itself can also crack due to localized overheating. On the other hand, the heat dissipation section 8 absorbs heat in the same way as the heating element lead electrode 7, thereby reducing the bias in the heat distribution on the insulating substrate 4 and preventing cracks. Furthermore, the heating element 5 itself is not locally overheated, which can prevent cracks from occurring.

[0048] This prevents damage to the insulating substrate 4 and the heating element 5 due to stress caused by uneven heat distribution, and allows the fuse element 2 to melt safely and quickly even when a high voltage is applied to the heating element 5.

[0049] The heat dissipation portion 8 may be made of any material that can absorb heat from the heat generating element 5, and may be made of a conductive material such as Ag, Cu, or an alloy thereof. The heat dissipation portion 8 may be formed by a known method such as screen printing.

[0050] 5, an insulating coating layer 17 may be formed to insulate the heat dissipation portion 8. By forming the insulating coating layer 17, it is possible to protect the heat dissipation portion 8 and, when the heat dissipation portion 8 is made of a conductive material, to prevent short circuits between the heat dissipation portion 8 and the heating element lead electrode 7, etc., thereby ensuring the electrical independence of the heat dissipation portion 8. The insulating coating layer 17 is made of, for example, a glass layer, and can be formed by screen printing a glass paste.

[0051] The heat dissipation section 8 is formed in an area of ​​the heat generating element 5 where the heat generating element lead electrode 7 is not provided, and overlaps the heat generating element 5 via the insulating layer 6. The heat dissipation section 8 may be formed only in the area overlapping the heat generating element 5, or may be formed from the area overlapping the heat generating element 5 to an area of ​​the insulating substrate 4 where the heat generating element 5 is not formed. Alternatively, as shown in Fig. 2, the heat dissipation section 8 may be formed over the surface and side surfaces of the insulating layer 6, thereby covering the surface and side surfaces of the heat generating element 5. This increases the heat absorption capacity and enables efficient heat absorption.

[0052] 6, the heat dissipation section 8 may be formed on the surface 4a of the insulating substrate 4 in an area where the various electrodes such as the heating element lead electrode 7, the heating element power supply electrode 12, and the heating element electrode 14 are not formed. The larger the area of ​​the heat dissipation section 8, the more effectively the uneven heat distribution on the insulating substrate 4 is eliminated, and damage to the insulating substrate 4 and the heating element 5 can be prevented even when a high voltage is applied. Note that, in order to eliminate uneven heat distribution on the insulating substrate 4, it is preferable that the heating element 5 and the heat dissipation section 8 of the fusing member 3 be formed symmetrically on the insulating substrate 4 in a plan view.

[0053] Furthermore, the heat dissipation section 8 is not connected to the heating element extraction electrode 7 or other electrodes and is electrically independent. This prevents the heat dissipation section 8 from having the same potential as the heating element extraction electrode 7, thereby preventing sparks (dielectric breakdown) between electrodes that would otherwise be generated due to a potential difference. A potential difference occurs between the adjacently formed tip 7a of the heating element extraction electrode 7 and the heating element power supply electrode 12, which could result in sparks being generated when a high potential is applied to the heating element 5. The impact of the sparks could damage the heating element extraction electrode 7 or the insulating substrate 4, preventing the fuse element 2 from melting quickly or causing the heating element 5 to stop generating heat. However, the electrically independent heat dissipation section 8 is formed between the electrodes 12, 7a, preventing sparks from being generated between the tip 7a of the heating element extraction electrode 7 and the heating element power supply electrode 12.

[0054] [Holding electrode] A holding electrode 10, an auxiliary electrode 15, and an external connection electrode 12a are formed on the back surface 4b of the dielectric breakdown 4, and are connected to the fuse element 2 by a connecting material such as connecting solder 9. The holding electrode 10 is formed in a position opposite the heating element lead electrode 7 formed in approximately the center of the front surface 4a, via the insulating substrate 4. The holding electrode 10 is also connected to the heating element lead electrode 7 via a through hole 11 that passes from the surface of the holding electrode 10 to the heating element lead electrode 7. As a result, the molten conductor 2a of the molten fuse element 2 is attracted toward the heating element lead electrode 7 through the through hole 11.

[0055] The auxiliary electrodes 15, together with the holding electrode 10, are connected to the fuse element 2 and hold the molten conductor 2a. The auxiliary electrodes 15 are formed on both edge portions of the insulating substrate 4 with the holding electrode 10 in between.

[0056] The holding electrode 10 and the auxiliary electrode 15 can be formed by a known method such as screen printing using a known electrode material such as Ag, Cu, or an alloy material containing Ag or Cu as a main component.

[0057] When the fuse element 2 melts, the through-hole 11 draws in the molten conductor 2a of the fuse element 2 by capillary action, thereby reducing the volume of the molten conductor 2a held on the holding electrode 10. As a result, even if the fuse element 2 becomes larger due to higher ratings and higher capacities of the protection device 1, resulting in an increased amount of melting, a large amount of molten conductor 2a can be held by the holding electrode 10, heating element lead electrode 7, and auxiliary electrode 15, as shown in Fig. 7, and the fuse element 2 can be reliably melted.

[0058] The through holes 11 are formed in areas of the insulating substrate 4 where no heating elements 5 are formed. In the fusing member 3 shown in FIG.

[0059] A conductive layer 24 is formed on the inner surface of the through hole 11. The conductive layer 24 is continuous with the holding electrode 10 and the heating element lead electrode 7. This electrically connects the holding electrode 10 and the heating element lead electrode 7 via the conductive layer 24. Furthermore, the formation of the conductive layer 24 allows the heat of the heating element 5 to be quickly conducted to the fuse element 2 via the heating element lead electrode 7 and the holding electrode 10.

[0060] Furthermore, the holding electrode 10 supports the fuse element 2 and, since the molten conductor 2a aggregates when the fuse element 2 is blown, the continuity of the holding electrode 10 and the conductive layer 24 makes it easier to guide the molten conductor 2a into the through hole 11. The molten conductor 2a also spreads and is held by the heating element extraction electrode 7, which is continuous with the conductive layer 24 (see FIGS. 7 and 8). Therefore, more molten conductor 2a can be attracted and held by the through hole 11 and the heating element extraction electrode 7, reducing the volume of the molten conductor 2a held by the holding electrode 10 and the auxiliary electrode 15 and ensuring blowout.

[0061] The conductive layer 24 is formed of, for example, any one of copper, silver, gold, iron, nickel, palladium, lead, and tin, or an alloy containing any one of these as a main component, and can be formed on the inner surface of the through hole 11 by a known method such as electrolytic plating or printing with a conductive paste. Alternatively, the conductive layer 24 may be formed by inserting a plurality of metal wires or an aggregate of conductive ribbons into the through hole 11.

[0062] The fusing member 3 may have a plurality of through holes 11. This increases the number of heat transfer paths in the heating element 5, allowing heat to be transferred to the fuse element 2 more quickly, and also increases the number of paths for attracting the molten conductor 2a of the fuse element 2, allowing more molten conductor 2a to be attracted more quickly, thereby reducing the volume of the molten conductor 2a at the fusing site.

[0063] [Fusing component formation process] The fusing member 3 is formed by forming the heating element power supply electrode 12 and the heating element electrode 14 on the front surface 4a of the insulating substrate 4 using a known forming method such as screen printing, followed by the formation of the heating element 5 and the lamination of the insulating layer 6. Next, the heat dissipation section 8 and the heating element lead electrode 7 are formed. The back surface 4b of the insulating substrate 4 is also formed using a known forming method such as screen printing, with the holding electrode 10, the external connection electrode 12a, and the auxiliary electrode 15. Thereafter, the through-hole 11 is formed using a drill or the like, and the conductive layer 24 is formed by plating or the like, completing the fusing member 3. The holding electrode 10 and the auxiliary electrode 15 are connected to the fuse element 2 with connecting solder 9. The fuse element 2, to which the fusing member 3 is connected, is then connected to first and second electrode terminals 21 and 22 supported on the side edge portion 30a of the lower case 30 using connecting solder 9. Furthermore, the external connection electrode 12 a of the insulating substrate 4 is connected to a third electrode terminal 23 supported on the side edge portion 30 a of the lower case 30 by a connection solder 9 .

[0064] [Fuse element clamping configuration] In the protection device 1 shown in Fig. 2, a fusing member 3 is connected to one surface and the other surface opposite to the one surface of the fuse element 2, thereby sandwiching the fuse element 2 between the multiple fusing members 3. Fig. 9 is a circuit diagram of the protection device 1. Each fusing member 3 connected to one surface and the other surface of the fuse element 2 has one end of a heating element 5 connected to the fuse element 2 via a heating element lead electrode 7 and a holding electrode 10 formed on each insulating substrate 4. Each fusing member 3 has a heating element power supply electrode 12 connected to the other end of the heating element 5, which is connected to a third electrode terminal 23 via a connecting material such as connection solder 9, and is connected to a power source for generating heat from the heating element 5 provided in an external circuit via the third electrode terminal 23.

[0065] 10, when the protective element 1 melts the fuse element 2 due to heat generated by the heating element 5, the heating elements 5 of the fusing members 3, 3 connected to both sides of the fuse element 2 generate heat, heating the fuse element 2 from both sides. Therefore, the protective element 1 can quickly heat and melt the fuse element 2 even when the cross-sectional area of ​​the fuse element 2 is increased to accommodate large current applications.

[0066] Furthermore, the protective element 1 draws the molten conductor 2a from both sides of the fuse element 2 into each through-hole 11 formed in each fusing member 3, and holds it with the heater lead-out electrode 7. Therefore, even when the cross-sectional area of ​​the fuse element 2 is increased to accommodate high-current applications and a large amount of molten conductor 2a is generated, the protective element 1 can reliably draw in the molten conductor 2a using the multiple fusing members 3, thereby melting the fuse element 2. Furthermore, by drawing in the molten conductor 2a using the multiple fusing members 3, the protective element 1 can more quickly melt the fuse element 2.

[0067] The protective element 1 can quickly fuse the fuse element 2 even when the fuse element 2 has a coating structure in which a low-melting-point metal constituting the inner layer is coated with a high-melting-point metal. That is, when the heating element 5 generates heat, the fuse element 2 coated with a high-melting-point metal takes time to heat up to a temperature at which the high-melting-point metal in the outer layer melts. Here, the protective element 1 includes multiple fusing members 3, and by simultaneously heating each heating element 5, the high-melting-point metal in the outer layer can be quickly heated to its melting temperature. Therefore, the protective element 1 can increase the thickness of the high-melting-point metal layer constituting the outer layer, thereby achieving a higher rating and maintaining fast-fusing characteristics.

[0068] 2, the protective element 1 is preferably connected to the fuse element 2 with a pair of opposing fusing members 3, 3. This allows the protective element 1 to heat the same location on the fuse element 2 from both sides simultaneously with the pair of fusing members 3, 3 and to attract the molten conductor 2a, enabling the fuse element 2 to be heated and blown more quickly.

[0069] Furthermore, in the protective element 1, it is preferable that the holding electrodes 10 and auxiliary electrodes 15 formed on the insulating substrates 4 of the pair of fusing members 3, 3 face each other via the fuse element 2. This symmetrically connects the pair of fusing members 3, 3, which prevents the load from being imbalanced on the fuse element 2 during reflow mounting or heating of the fuse element 2, and improves resistance to deformation of the fuse element 2 and misalignment of the fusing members 3.

[0070] It is preferable that the heating element 5 be formed on both sides of the through hole 11 in order to heat the holding electrode 10 and the heating element lead electrode 7 and to aggregate and attract a larger amount of the molten conductor 2a.

[0071] [Fuse element] The fuse element 2 is mounted across the first and second electrode terminals 21, 22, and melts down due to heat generated by the passage of current through the heating element 5 or due to self-heating (Joule heat) caused by the passage of a current exceeding the rated value, thereby interrupting the current path between the first electrode terminal 21 and the second electrode terminal 22.

[0072] The fuse element 2 may be made of any conductive material that melts when heated by the passage of current through the heating element 5 or when an overcurrent occurs. For example, in addition to SnAgCu-based Pb-free solder, BiPbSn alloys, BiPb alloys, BiSn alloys, SnPb alloys, PbIn alloys, ZnAl alloys, InSn alloys, PbAgSn alloys, etc. may be used.

[0073] 11 , the fuse element 2 is a laminated structure including an inner layer and an outer layer, with 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 2 is connected to the first and second electrode terminals 21 and 22, the holding electrode 10, and the auxiliary electrode 15 via a bonding material such as a connection solder 9.

[0074] The low-melting-point metal layer 26 is preferably a solder or a metal containing Sn as a main component, a material commonly referred to as "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; it may melt at approximately 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, a metal containing Ag or Cu as a main component, or either of these, and has a high melting point that prevents it from melting even when the first and second electrode terminals 21 and 22, the holding electrode 10, and the auxiliary electrode 15 are connected to the fuse element 2 by reflow.

[0075] Such a fuse element 2 can be formed by depositing a high-melting-point metal layer on a low-melting-point metal foil using a plating technique, or by using other well-known lamination or film-forming techniques. The fuse element 2 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 2 may have a 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. Alternatively, the fuse element 2 may have a multilayer structure of three or more layers in which low-melting-point metal layers and high-melting-point metal layers are alternately laminated, or an opening is provided in part of the outer layer to expose part of the inner layer.

[0076] By laminating the high-melting-point metal layer 27 as an outer layer on the low-melting-point metal layer 26 as an inner layer, the fuse element 2 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 first and second electrode terminals 21 and 22, the holding electrode 10, and the auxiliary electrode 15 can be efficiently connected to the fuse element 2 by reflow. Furthermore, even if the fuse element 2 is deformed by reflow, the resistance value can be locally increased or decreased, preventing variations in the fusing characteristics, such as not melting at a predetermined temperature or melting below the predetermined temperature. Therefore, the protection device 1 can quickly melt the fuse element 2 by a predetermined overcurrent or heat generated by the heating element 5.

[0077] Furthermore, the fuse element 2 will not melt even if it generates heat as long as a predetermined rated current flows through it. When a current higher than the rated current flows through it, it melts due to self-heating (Joule heat) and cuts off the current path between the first and second electrode terminals 21 and 22.

[0078] When the heating element 5 is energized and generates heat, the fuse element 2 melts and cuts off the current path between the first and second electrode terminals 21 and 22. At this time, the molten low-melting-point metal layer 26 of the fuse element 2 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 its melting point. Therefore, the fuse element 2 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. Furthermore, the fuse element 2 is cut off by the physical attraction of the molten conductor 2a by the holding electrode 10 and the auxiliary electrode 15, so the current path between the first and second electrode terminals 21 and 22 can be quickly and reliably cut off (FIGS. 8 and 10).

[0079] Furthermore, the fuse element 2 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. When the fuse element 2 is heated by self-heating due to an overcurrent or by heat generated by the heating element 5, the low-melting-point metal melts and corrodes the high-melting-point metal, thereby enabling the fuse element 2 to melt and blow quickly. Therefore, by configuring 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 2 can promote this corrosion action and quickly disconnect the first and second electrode terminals 21, 22.

[0080] Furthermore, in the fuse element 2, which is constructed by laminating a high-melting-point metal layer 27 on a low-melting-point metal layer 26 that serves as an inner layer, the fusing temperature can be significantly reduced compared to conventional chip fuses made of high-melting-point metals. Therefore, the fuse element 2 can have a larger cross-sectional area and a significantly higher current rating than chip fuses of the same size. Furthermore, it can be made smaller and thinner than conventional chip fuses with the same current rating, and has excellent fast-fusing properties.

[0081] Furthermore, the fuse element 2 can improve its resistance (pulse resistance) to surges, which are instantaneous applications of abnormally high voltages to electrical systems incorporating the protective device 1. In other words, the fuse element 2 must not blow even when a current of, for example, 100 A flows for several milliseconds. Since a large current that flows in an extremely short time flows through the surface layer of a conductor (skin effect), a fuse element 2 having a low-resistance, high-melting-point metal layer 27 such as Ag plating as its outer layer can easily pass the current applied by a surge and prevent blowout due to self-heating. Therefore, the fuse element 2 can significantly improve its resistance to surges compared to fuses made of conventional solder alloys.

[0082] The fuse element 2 may be coated with flux (not shown) to prevent oxidation and improve wettability during melting.

[0083] The first and second electrode terminals 21, 22 connected to the ends of the fuse element 2 are conductive terminals and are provided on both the inside and outside of the case 28 of the protection device 1. The first and second electrode terminals 21, 22 have screw holes 20 at their tips that extend outside the case 28, allowing them to be connected by screws or the like to connection electrodes provided on an external circuit.

[0084] In addition, the third electrode terminal 23, which is connected to the external connection electrode 12a connected to the above-mentioned heating element power supply electrode 12, is similarly provided both inside and outside the case 28 of the protection element 1, and a screw hole 20 is provided at the tip portion extending outside the case 28.

[0085] [case] The inside of the protection device 1 is protected by covering the fuse element 2 and the fusing member 3 with a case 28. The case 28 can be formed using insulating materials such as various engineering plastics, thermoplastic plastics, ceramics, and glass epoxy boards. The case 28 houses the fuse element 2 and the fusing member 3 and has an internal space sufficient to allow the molten conductor 2a to expand spherically and condense on the heating element lead electrode 7 when the fuse element 2 melts.

[0086] 2 and 12, the case 28 is formed by combining an upper case 29 and a lower case 30. The lower case 30 is formed in a substantially rectangular shape and has side edge portions 30a that support the first to third electrode terminals 21 to 23, and a hollow portion 30b in which the fusing member 3 connected to the underside of the fuse element 2 is located.

[0087] The side edge portion 30a supports the first to third electrode terminals 21 to 23 from the inside to the outside of the case 28. The hollow portion 30b accommodates the fusing member 3 connected to the underside of the fuse element 2, and has an internal space in which the molten conductor 2a can wet, spread, and coagulate over the heating element lead electrode 7.

[0088] The upper case 29 is formed in a substantially rectangular shape like the lower case 30, and is butt-joined to the lower case 30 to cover the fuse element 2 and the fusing member 3 connected to the upper surface of the fuse element 2. The upper case 29 also has an internal space in which the molten conductor 2a can wet, spread, and condense over the heating element lead electrode 7.

[0089] [Circuit configuration example] Such a protection device 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. 13. 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.

[0090] The battery pack 40 includes a battery stack 45, a charge / discharge control circuit 46 that controls the 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 voltage of each battery cell 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.

[0091] 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.

[0092] The charge / discharge control circuit 46 includes two current control elements 43a, 43b connected in series in 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 configured, for example, with 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 and / or discharging directions. 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 over-discharged or over-charged according to the detection result by the detection circuit 47.

[0093] 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 .

[0094] The detection circuit 47 is connected to each of the battery cells 41a to 41d, detects the voltage value of each of the battery cells 41a to 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 to 41d reaches an overcharge voltage or an overdischarge voltage.

[0095] The current control element 48 is configured, for example, by a FET, and when the detection signal output from the detection circuit 47 indicates that the voltage value of the battery cells 41a to 41d exceeds a predetermined over-discharge or over-charge state, it activates the protection element 1 and controls 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 and 43b.

[0096] 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. 9 . Specifically, the protection element 1 has a first electrode terminal 21 connected to the battery stack 45 and a second electrode terminal 22 connected to the positive terminal 40a, thereby connecting the fuse element 2 in series to the charge / discharge path of the battery stack 45. The protection element 1 also has a heating element 5 connected to the current control element 48 via the heating element power supply electrode 12 and the third electrode terminal 23, and also connected to an open end of the battery stack 45. As a result, one end of the heating element 5 is connected to the fuse element 2 and one open end of the battery stack 45 via the heating element lead electrode 7 and the holding electrode 10, and the other end is connected to the current control element 48 and the other open end of the battery stack 45 via the third electrode terminal 23. This completes a power supply path to the heating element 5, the current supply path of which is controlled by the current control element 48.

[0097] [Protection element operation] By mounting the protection element 1 on the external circuit board, the heating element 5 is connected to a current control element 48 and the like formed in the external circuit via the third electrode terminal 23, and current flow and heat generation are regulated under normal conditions. 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. The current control element 48 then controls the current to flow through the heating element 5. When a current flows from the battery stack 45, the heating element 5 begins to generate heat.

[0098] Heat from the heating element 5 is transferred to the fuse element 2 via the heating element lead electrode 7, through hole 11, and holding electrode 10, causing the fuse element 2 to melt. In the fuse element 2, the molten conductor 2a condenses on the holding electrode 10, auxiliary electrode 15, and heating element lead electrode 7, causing the fuse element 2 to melt between the holding electrode 10 and auxiliary electrode 15 (FIGS. 8 and 10).

[0099] The heat from the heating element 5 is transferred from the insulating substrate 4 to the fuse element 2 via the holding electrode 10 and auxiliary electrode 15. In addition, by forming the fuse element 2 of the protection device 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 corrodes the high-melting point metal, allowing the fuse element 2 to melt in a short time.

[0100] When the fuse element 2 melts, the charge / discharge path of the battery stack 45 is cut off between the first and second electrode terminals 21, 22. When the fuse element 2 melts, the power supply path to the heating element 5 is also cut off, and the heating element 5 stops generating heat.

[0101] Here, the protection element 1 has a heat dissipation section 8 electrically independent from the heating element lead electrode 7 formed on the surface 4a side of the insulating substrate 4, at least in the region overlapping with the heating element 5. This allows the protection element 1 to prevent damage to the insulating substrate 4 and the heating element 5 due to stress caused by uneven heat distribution, and allows the fuse element 2 to blow safely and quickly even when a high voltage is applied to the heating element 5. Furthermore, by forming the heat dissipation section 8, the protection element 1 is less likely to generate sparks (discharges) even when a high voltage is applied to the heating element power supply electrode 12 from a battery stack 45 that supports large current applications, and can safely and quickly interrupt the current path.

[0102] Even when an overcurrent exceeding the rated current flows through the fuse element 2, the protective element 1 melts due to self-heating of the fuse element 2, thereby cutting off the charge / discharge path of the battery pack 40.

[0103] The protection device 1 according to the present invention is not limited to use in a battery pack for lithium ion secondary batteries, and can of course be applied to various uses that require the interruption of a current path by an electrical signal.

[0104] [Convex] 14 and 15, the protective element 1 may have protrusions 50 formed on the case 28 that come into contact with the heat dissipation portion 8 and absorb heat. The protrusions 50 are formed to protrude from the upper case 29 and the lower case 30, and their tips come into contact with the heat dissipation portion 8. This allows the heat absorbed by the heat dissipation portion 8 to be diffused to the protrusions 50 and the case 28, enabling more efficient heat diffusion.

[0105] The protrusions 50 are formed to protrude from the top surface of the upper case 29 and the bottom surface of the hollow portion 30b of the lower case 30. The protrusions 50 may be formed integrally with the upper case 29 and the lower case 30, or may be formed from separate members from the upper case 29 and the lower case 30 and connected by adhesive or the like.

[0106] The shape of the protrusions 50 is not particularly limited, and they can be formed in any shape, such as a rectangular pillar or a cylindrical shape. Furthermore, the surface area may be increased to promote thermal diffusion, for example, by forming irregularities or grooves on the outer periphery of the protrusions 50. Furthermore, when the protrusions 50 are formed as separate members from the case 28, the protrusions 50 may be formed from a material with a higher thermal conductivity than the material of the case 28.

[0107] The tips of the protrusions 50 are flat. This ensures a wide contact area with the heat dissipation unit 8. Furthermore, to ensure surface contact between the tips of the protrusions 50 and the heat dissipation unit 8, a resin agent, resin sheet, or the like having excellent thermal conductivity and heat resistance may be interposed. This ensures a wide contact area even when the contact surfaces of the tips of the protrusions 50 and the heat dissipation unit 8 are not parallel to each other or are rough, and prevents a decrease in the efficiency of heat conduction to the protrusions 50.

[0108] Furthermore, the convex portion 50 may be in contact only with the area of ​​the heat dissipation portion 8 that overlaps with the heating element 5, or may be in contact with an area that includes the area that overlaps with the heating element 5 and areas other than the area that overlaps with the heating element 5.

[0109] [Heat dissipation element] 16 and 17, the protective element 1 may be provided with a heat dissipation element 51 that comes into contact with the heat dissipation portion 8 and absorbs and dissipates heat from the heat dissipation portion 8. The heat dissipation element 51 comes into contact with the heat dissipation portion 8 to absorb heat from the heat dissipation portion 8 and dissipate the heat into the space within the case 28. By providing the heat dissipation element 51, the protective element 1 can efficiently dissipate heat.

[0110] The heat dissipation element 51 can be preferably made of a material with excellent thermal conductivity, such as a high-melting-point metal, a resin material coated with a high-melting-point metal, or a heat sink (FIG. 18). There are no particular restrictions on the size or shape of the heat dissipation element 51, but it preferably has a thermal capacity that can sufficiently absorb the heat from the heat dissipation unit 8 and a surface area that can efficiently dissipate heat into the case 28. The heat dissipation element 51 may have an increased surface area by forming unevenness or grooves on the outer periphery that contacts the internal space of the case 28, thereby promoting heat diffusion. It is preferable that at least the portion of the heat dissipation element 51 that contacts the heat dissipation unit 8 be flat to ensure a large contact area with the heat dissipation unit 8.

[0111] The heat dissipation element 51 is connected to the heat dissipation section 8 by a connecting material such as high-melting-point solder or a thermally conductive sheet with tackiness. The reason why high-melting-point solder or the like is used as the connecting material is that it must not melt due to the heat of the heat dissipation section 8. If the connecting material were to melt due to the heat of the heat dissipation section 8, there is a risk that the heat dissipation element 51 may fall off or that the heat dissipation element, such as a high-melting-point metal, may melt.

[0112] In addition, the heat dissipation element 51 may be in contact only with the area of ​​the heat dissipation section 8 that overlaps with the heat generating element 5, or may be in contact with an area that includes the area that overlaps with the heat generating element 5 and areas other than the area that overlaps with the heat generating element 5. [Example]

[0113] An example of the protective element 1 will be described. In this example, the protective element shown in Fig. 2 was prepared as an example, and the protective element without a heat dissipation part shown in Fig. 40 was prepared as a comparative example, and the presence or absence of damage to the heating element or insulating substrate was determined when voltages of 50 V, 60 V, 80 V, and 100 V were applied to each. The case where no damage was observed in the heating element or insulating substrate was evaluated as ◯ (good), and the case where damage was observed in the heating element or insulating substrate was evaluated as × (bad).

[0114] [Table 1]

[0115] As shown in Table 1, in the example in which a heat dissipation portion was formed, no damage was observed to the heating element or insulating substrate even when the applied voltage was increased, and the fuse element was able to blow quickly. On the other hand, in the protection element according to the comparative example in which a heat dissipation portion was not provided, damage to the heating element or insulating substrate was observed when the applied voltage was 60 V or higher. For this reason, in the comparative example, it took a long time for the fuse element to blow, and there were cases in which the heating element was damaged and the fuse element could not be blown completely.

[0116] [Variation 1] Next, modified examples of the protection element will be described. Note that in the following description, the same components as those of the protection element 1 described above will be assigned the same reference numerals, and their details may be omitted. As shown in FIG. 19 , a protection element 60 to which the present technology is applied has a heating element lead electrode 7 connected to a fuse element 2. As shown in FIGS. 19 and 20 , in the protection element 60, auxiliary electrodes 15 are formed on both edge portions of the surface 4 a of the insulating substrate 4 that sandwich the heating element lead electrode 7, and the auxiliary electrodes 15 and the heating element lead electrode 7 are connected to the fuse element 2 by connection solder 9. That is, in the protection element 60, the surface 4 a of the insulating substrate 4 on which the heating element 5, insulating layer 6, heating element lead electrode 7, and heat dissipation portion 8 are formed is the surface that comes into contact with the fuse element 2. When the heating element 5 generates heat, the fuse element 2 is heated via the heating element lead electrode 7.

[0117] Furthermore, the insulating substrate 4 of the protection element 60 has a holding electrode 10 formed on a back surface 4b opposite to the front surface 4a that contacts the fuse element 2. The molten conductor 2a of the fuse element 2 is attracted to and held by the holding electrode 10, which is continuous with the heating element lead electrode 7 via a through hole 11.

[0118] As with the protective element 1, the protective element 60 also has a heat dissipation portion 8 electrically independent from the heater lead electrode 7 formed on the front surface 4a of the insulating substrate 4, at least in the region overlapping with the heater 5. Therefore, the protective element 60 can prevent damage to the insulating substrate 4 and the heater 5 due to stress caused by uneven heat distribution, and can safely and quickly melt the fuse element 2 even when a high voltage is applied to the heater 5. Furthermore, by forming the heat dissipation portion 8, the protective element 60 is less likely to generate sparks (discharges) even when a high voltage is applied to the heater power supply electrode 12, and can safely and quickly interrupt the current path. Therefore, the protective element 60 can be made to have a high rating to accommodate large current applications.

[0119] It is preferable that the protective element 60 also has an insulating coating layer 17 formed thereon to insulate the heat sink 8. By forming the insulating coating layer 17, it is possible to prevent electrical conduction between the fuse element 2 and the heat sink lead electrode 7, even when the heat sink 8 is made of a conductive material.

[0120] [Variation 2] The above-described protective elements 1 and 60 connect the fusing member 3 to the fuse element 2, but a protective element to which the present technology is applied may have a structure in which the fuse element 2 is mounted on an insulating substrate 4 and the fusing member is surface-mounted on an external circuit board, as shown in Fig. 21. In the following description, the same components as those in the above-described protective elements 1 and 60 are denoted by the same reference numerals, and detailed descriptions thereof may be omitted.

[0121] 21 includes a fuse element 2 and a fusing member 71. The fusing member 71 includes an insulating substrate 4, a heating element 5 formed on the surface 4a of the insulating substrate 4, an insulating layer 6 covering the heating element 5, a heating element lead electrode 7 connected to the heating element 5 and overlapping the heating element 5 via the insulating layer 6, a heat dissipation portion 8 formed on the surface 4a of the insulating substrate 4 in at least a region overlapping the heating element 5 and electrically independent from the heating element lead electrode 7, and a first electrode 72 and a second electrode 73 formed on the surface 4a of the insulating substrate 4 and connected to an external circuit.

[0122] The fuse element 2 is connected to the first electrode 72, the second electrode 73, and the heating element extraction electrode 7 provided between the first electrode 72 and the second electrode 73 by a conductive connecting material such as connecting solder 9.

[0123] The first and second electrodes 72, 73 are formed on opposite side edges of the front surface 4a of the insulating substrate 4. The insulating substrate 4 also has the heater power supply electrode 12 and the heater electrode 14 formed on opposite side edges different from the side edges on the front surface 4a where the first and second electrodes 72, 73 are formed. As shown in Figure 21(C), the insulating substrate 4 also has first to third external connection electrodes 74-76 formed on the back surface 4b to be connected to an external circuit board.

[0124] The first and second electrodes 72, 73 are each formed of a conductive pattern of Ag, Cu, or the like. Preferably, the surfaces of the first and second electrodes 72, 73 are coated with a film such as Ni / Au plating, Ni / Pd plating, or Ni / Pd / Au plating by a known method such as plating. This prevents oxidation of the first and second electrodes 72, 73 and prevents fluctuations in rating due to increases in conduction resistance. Furthermore, when the fuse element 2 is reflow-mounted to the first and second electrodes 72, 73 or when the fusing member 71 is reflow-mounted to an external circuit board, the first and second electrodes 72, 73 are prevented from being corroded (soldered) by melting the connecting solder 9 connecting the fuse element 2.

[0125] The first electrode 72 is continuous from the front surface 4a of the insulating substrate 4 via castellations to a first external connection electrode 74 formed on the back surface 4b. The second electrode 73 is continuous from the front surface 4a of the insulating substrate 4 via castellations to a second external connection electrode 75 formed on the back surface 4b. The first and second external connection electrodes 74, 75 of the fusing member 71 are connected to connection electrodes provided on an external circuit board on which the fusing member 71 is mounted, thereby incorporating the fuse element 2 into part of a current path formed on the circuit board.

[0126] The first and second electrodes 72, 73 are electrically connected by mounting the fuse element 2 with a conductive connecting material such as connecting solder 9. As shown in Fig. 22, the first and second electrodes 72, 73 are interrupted when the heating element 5 generates heat as current flows and melts the fuse element 2. Alternatively, the first and second electrodes 72, 73 are interrupted when a large current exceeding the rated current flows through the protective element 70 and melts the fuse element 2 due to self-heating (Joule heat).

[0127] In the fusing member 71, one heating element 5 is formed on the front surface 4a of the insulating substrate 4. One end of the heating element 5 is connected to a heating element power supply electrode 12, and the other end is connected to a heating element electrode 14. The heating element power supply electrode 12 is an electrode connected to one end of the heating element 5 and serves as a power supply terminal to the heating element 5, and is continuous with a third external connection electrode 76 formed on the back surface 4b of the insulating substrate 4 via a castellation. The heating element electrode 14 is connected to the heating element lead electrode 7.

[0128] The heating element 5 is covered with an insulating layer 6 and overlapped with a heating element lead electrode 7 formed on the insulating layer 6. The heating element lead electrode 7 is connected to a fuse element 2 provided between the first and second electrodes 72, 73 via a bonding material such as connection solder 9.

[0129] The heating element 5 is connected to a current control element or the like formed in an external circuit via the third external connection electrode 76 by mounting the fusing member 71 on an external circuit board, and current and heat generation are regulated under normal conditions. The heating element 5 is energized via the third external connection electrode 76 at a predetermined timing when the current path of the external circuit is interrupted, generating heat. The protective element 70 transfers heat from the heating element 5 from the heating element electrode 14 through the heating element lead electrode 7, and then through the insulating layer 6 and the heating element lead electrode 7 to the fuse element 2, thereby melting the fuse element 2 connecting the first and second electrodes 72, 73. As shown in FIG. 22 , the molten conductor 2a of the fuse element 2 condenses on the heating element lead electrode 7 and the first and second electrodes 72, 73, thereby interrupting the current path between the first and second electrodes 72, 73. Furthermore, when the fuse element 2 melts, the heating element 5's own current path is also interrupted, and heat generation ceases.

[0130] It is preferable that the first and second electrodes 72, 73 and the heater power supply electrode 12 be provided with a restriction wall (not shown) to prevent connection solder provided on the electrodes of the external circuit board connected to the first to third external connection electrodes 74-76 from melting during reflow mounting or the like and creeping up and spreading onto the first and second electrodes 72, 73 and the heater power supply electrode 12 via castellations. The restriction wall can be formed using an insulating material that is not wettable by solder, such as glass, solder resist, or an insulating adhesive, and can be formed on the first and second electrodes 72, 73 and the heater power supply electrode 12 by printing or the like. The provision of the restriction wall prevents the molten connection solder from wetting and spreading to the first and second electrodes 72, 73 and the heater power supply electrode 12, thereby maintaining the connectivity between the fusing member 71 and the external circuit board.

[0131] [Heat dissipation part] The heat dissipation section 8 is formed at least in the region overlapping with the heating element 5 so as to be electrically independent from the heating element lead electrode 7. For example, as shown in FIG. 21(A), the heat dissipation section 8 is formed so as to cross the heating element power supply electrode 12 side of the heating element 5. The heat dissipation section 8 is also provided on the insulating layer 6, and is provided spaced apart from the heating element lead electrode 7 and the fuse element 2 connected to the heating element lead electrode 7. This makes the heat dissipation section 8 electrically independent from the power supply path to the heating element 5 and the current path of the external circuit.

[0132] In the protective element 70, as in the protective elements 1 and 60, the heat dissipation section 8 absorbs the heat from the heating element 5, thereby reducing the unevenness of the heat distribution on the insulating substrate 4 and suppressing damage (thermal shock cracks) to the insulating substrate 4 and the heating element 5 due to localized concentration of heat from the heating element 5.

[0133] Also, in the protective element 70, an insulating coating layer 17 may be formed to insulate the heat dissipation portion 8. As shown in Fig. 23, the heat dissipation portion 8 may be formed only on the insulating layer 6, or as shown in Fig. 24, the heat dissipation portion 8 may be formed over as wide a range as possible by extending from the region overlapping with the heating element 5 to a region on the surface 4a of the insulating substrate 4 where no electrodes such as the heating element power supply electrode 12 are formed.

[0134] [Heater element extraction electrode] The heater lead electrode 7 has one end connected to the heater electrode 14, is formed on the insulating layer 6, and overlaps the heater 5 via the insulating layer 6. Similar to the protection element 1, the heater lead electrode 7 has a wide base 7b and a narrow tip 7a protruding from the base 7b.

[0135] By providing a wide base 7b on the heating element extraction electrode 7, the capacity for holding the molten conductor 2a of the fuse element 2 can be increased on the base 7b side, thereby ensuring that the fuse element 2 is blown and reducing the risk of a short circuit between the heat dissipation portion 8 provided at the tip of the tip 7a and the molten conductor 2a.

[0136] The heater element extraction electrode 7 preferably has a fuse element 2 mounted thereon, and the tip 7a of the heater element extraction electrode 7 does not protrude beyond the side edge of the fuse element 2 toward the heater element power supply electrode 12. Because a high voltage is applied to the heater element power supply electrode 12, the heater element extraction electrode 7 can be separated from the high potential by retracting the heater element extraction electrode 7 toward the low potential portion from the fuse element 2. If the tip 7a of the heater element extraction electrode 7 protrudes beyond the side edge of the fuse element 2 toward the heater element power supply electrode 12, the tip 7a may act as a lightning rod. However, this configuration prevents the formation of such a lightning rod-like portion, thereby reducing the risk of sparks. Furthermore, the overlapping of the heater element extraction electrode 7 and the fuse element 2 increases the volume of the metal (i.e., the tip 7a and the fuse element 2) facing the heater element power supply electrode 12, which is at a high potential. This improves shock resistance and prevents damage even if a spark occurs.

[0137] [Circuit configuration] FIG. 25 is a circuit diagram of the protection element 70. When the protection element 70 is used as the protection element for the battery pack 40 shown in FIG. 13, the first external connection electrode 74 is connected to the battery stack 45, and the second external connection electrode 75 is connected to the positive terminal 40a, thereby connecting the fuse element 2 in series to the charge / discharge path of the battery stack 45. In addition, in the protection element 70, the heating element 5 is connected to the current control element 48 via the heating element power supply electrode 12 and the third external connection electrode 76, and the heating element 5 is connected to an open end of the battery stack 45. As a result, one end of the heating element 5 is connected to the fuse element 2 and one open end of the battery stack 45 via the heating element lead-out electrode 7, and the other end is connected to the current control element 48 and the other open end of the battery stack 45 via the third external connection electrode 76, thereby forming a power supply path to the heating element 5, the current supply path to which is controlled by the current control element 48.

[0138] The connection between the protection element 70 and an external circuit such as a battery circuit can be achieved, for example, by mounting the fusing member 71 on an external circuit board by reflow mounting or the like. That is, the fusing member 71 is mounted on the external circuit board by placing the first to third external connection electrodes 74 to 76 formed on the back surface 4b of the insulating substrate 4 on lands provided at predetermined mounting positions on the external circuit board via a connecting material such as connecting solder, and passing through a reflow furnace. This allows the fuse element 2 to be incorporated into the current path of the external circuit.

[0139] [Protection element operation] When detection circuit 47 detects an abnormal voltage in any of battery cells 41a to 41d, it outputs a cutoff signal to current control element 48. In response, current control element 48 controls the current to pass through heating element 5. Protection element 70 allows current to flow from battery stack 45 to heating element 5, causing heating element 5 to start generating heat. In protection element 70, heat generated by heating element 5 melts fuse element 2, cutting off the charge / discharge path of battery stack 45 (FIG. 22). Furthermore, protection element 70 forms fuse element 2 containing a high-melting-point metal and a low-melting-point metal, so that the low-melting-point metal melts before the high-melting-point metal melts, and the molten low-melting-point metal corrodes the high-melting-point metal, thereby melting fuse element 2 in a short time.

[0140] At this time, the heat dissipation portion 8 of the protective element 70 absorbs the heat from the heating element 5, thereby reducing uneven heat distribution on the insulating substrate 4 and suppressing damage (thermal shock cracking) to the insulating substrate 4 and the heating element 5 due to localized concentration of heat from the heating element 5. Furthermore, the heat dissipation portion 8 of the protective element 70 formed between the tip 7a of the heating element lead electrode 7 and the heating element power supply electrode 12 is electrically independent from the heating element lead electrode 7, thereby suppressing the occurrence of sparks (dielectric breakdown) between the tip 7a of the heating element lead electrode 7 and the heating element power supply electrode 12. As a result, the protective element 70 can safely and quickly fuse the fuse element 2 and interrupt the current path even when a high voltage is applied to the heating element 5 from a battery stack 45 that is designed for large current applications.

[0141] When the fuse element 2 melts, the protective element 70 also cuts off the power supply path to the heating element 5, and the heating element 5 stops generating heat.

[0142] Even when an overcurrent exceeding the rated current flows through the fuse element 2, the protective element 70 melts the fuse element 2 due to self-heating, thereby cutting off the charge / discharge path of the battery pack 40.

[0143] In this way, the fuse element 2 of the protective element 70 melts due to heat generated by the passage of current through the heating element 5 or due to self-heating of the fuse element 2 caused by an overcurrent. At this time, deformation of the fuse element 2 is suppressed by forming the fuse element 2 in a configuration in which a low-melting-point metal is coated with a high-melting-point metal, even when the fuse element 2 is reflow-mounted on the insulating substrate 4, when the fusing member 71 is reflow-mounted on the circuit board, or when the circuit board on which the protective element 70 is mounted is further exposed to a high-temperature environment such as reflow heating. Therefore, fluctuations in fusing characteristics due to fluctuations in resistance value caused by deformation of the fuse element 2 are prevented, and the fuse element 2 can be melted quickly by a predetermined overcurrent or heat generated by the heating element 5.

[0144] [Variation 3] In the above-described protection element 70, the first and second electrodes 72, 73 and the heating element lead electrode 7 are formed on the front surface 4a of the insulating substrate 4 on which the heating element 5 is formed, and the fuse element 2 is mounted, but the electrodes 72, 73, 7 and the fuse element 2 may also be formed on the back surface 4b of the insulating substrate 4. In the following description, the same components as those in the above-described protection elements 1, 60, 70 are denoted by the same reference numerals, and detailed descriptions thereof may be omitted.

[0145] 26 includes a fuse element 2 and a fusing member 81. The fusing member 81 has a heating element power supply electrode 12, a heating element electrode 14, a heating element 5, an insulating layer 6, a first external connection electrode 74, and a second external connection electrode 75 formed on the front surface 4a of an insulating substrate 4. The protective element 80 has a heating element electrode 14, a heating element lead electrode 7, a first electrode 72, a second electrode 73, and a heat dissipation portion 8 formed on the back surface 4b of the insulating substrate 4, and a fuse element 2 mounted from the first electrode 72 through the heating element lead electrode 7 to the second electrode 73.

[0146] The heating element electrodes 14 are formed on the front surface 4a and the back surface 4b of the insulating substrate 4, respectively, and both heating element electrodes 14 are electrically connected via castellations. The heating element lead electrode 7 is electrically connected to the heating element 5 provided on the front surface 4a of the insulating substrate 4 via the heating element electrodes 14 provided on the front surface 4a and the back surface 4b of the insulating substrate 4. Furthermore, the front surface 4a of the insulating substrate 4 is used as the mounting surface for the protection element 80 to an external circuit board, and the heating element power supply electrode 12, the first external connection electrode 74, and the second external connection electrode 75 are connected via connecting materials such as connecting solder to lands provided at predetermined mounting positions on the external circuit board.

[0147] In the protection element 80, the heat dissipation section 8 is also formed electrically independent from the heater lead electrode 7 in a region that overlaps at least with the heater 5 via the insulating substrate 4. For example, the heat dissipation section 8 is formed across both side edges of the insulating substrate 4 where the first and second electrodes 72, 73 are provided, so as to cross the heater power supply electrode 12 side of the heater 5. Furthermore, by being provided at a distance from the heater lead electrode 7 and the fuse element 2 connected to the heater lead electrode 7, the heat dissipation section 8 is electrically independent from the power supply path to the heater 5 and the current path of the external circuit.

[0148] Also in the protective element 80, by forming the heat dissipation portion 8, the heat generated by the heating element 5 is absorbed from the rear surface 4b side of the insulating substrate 4. Therefore, uneven heat distribution on the insulating substrate 4 is reduced, and damage (thermal shock cracks) to the insulating substrate 4 and the heating element 5 caused by localized concentration of heat from the heating element 5 in areas where the heating element lead electrode 7 is not formed can be suppressed.

[0149] An attraction electrode 83 connected to the heating element power supply electrode 12 via a castellation is provided on the back surface 4b of the insulating substrate 4. The attraction electrode 83 attracts the connection solder connecting the heating element power supply electrode 12 to the land portion so that it wets and spreads over the entire wall surface of the castellation.

[0150] 27, an insulating coating layer 17 may also be formed on the protection element 80 to insulate the heat dissipation portion 8. As shown in Fig. 28, the heat dissipation portion 8 may be formed over as wide an area as possible by extending from the area overlapping with the heating element 5 to the side edge where the heating element power supply electrode 12 is formed. Fig. 29 is a plan view showing a configuration in which the heat dissipation portion 8 is expanded as much as possible and is covered with the insulating coating layer 17.

[0151] 31, the attracting electrode 83 may not be formed, and the heat dissipation portion 8 may be formed as wide as possible. In this case, the heat dissipation portion 8 is separated from the castellations and maintains electrical independence. In this configuration, the heat dissipation portion 8 may also be covered with an insulating coating layer 17.

[0152] Furthermore, the protection element 80 may have a second heat dissipation portion 82 formed on the surface 4a of the insulating substrate 4. As shown in FIG. 30 , the second heat dissipation portion 82 can be formed using the same material and method as the heat dissipation portion 8, and is formed on the insulating layer 6 so as to overlap the heating element 5. The second heat dissipation portion 82 is also covered with an insulating coating layer 17. The second heat dissipation portion 82 also absorbs the heat from the heating element 5, thereby reducing the amount of heat transferred to the insulating substrate 4 and preventing overheating of the heating element 5 itself, thereby suppressing damage (thermal shock cracking) to the insulating substrate 4 and the heating element 5.

[0153] [Variation 4] Furthermore, a protection element having a structure in which a fusing member is surface-mounted on an external circuit board may have a plurality of heating elements on the surface 4a of the insulating substrate 4. In the following description, the same members as those in the protection elements 1, 60, 70, and 80 described above will be assigned the same reference numerals, and detailed descriptions thereof may be omitted.

[0154] A protection element 90 shown in FIG. 32 includes a fuse element 2 and a fusing member 91. The fusing member 91 has a plurality of heating elements 5 arranged in parallel and spaced apart on the front surface 4a of an insulating substrate 4. As with the protection element 70, first and second electrodes 72 and 73, a heating element lead electrode 7, a heating element power supply electrode 12, and a heating element electrode 14 are formed on the front surface 4a of the insulating substrate 4, and first to third external connection electrodes 74 to 76 are formed on the back surface 4b of the insulating substrate 4. Furthermore, the protection element 90 has a holding electrode 10 formed on the back surface 4b of the insulating substrate 4. As shown in FIG. 33, the insulating substrate 4 has through holes 11 formed between the parallel heating elements 5, which are areas where no heating elements 5 are formed, connecting the heating element lead electrode 7 formed on the front surface 4a to the holding electrode 10 formed on the back surface 4b. 33(A) is a cross-sectional view taken along line AA' in FIG. 32(A), and FIG. 33(B) is a cross-sectional view taken along line BB' in FIG. 32(A).

[0155] One end of each heating element 5 is connected to a heating element power supply electrode 12, and the other end is connected to a heating element electrode 14. The heating element electrode 14 is connected to a heating element lead electrode 7. Each heating element 5 is covered with an insulating layer 6, and overlaps with the heating element lead electrode 7 formed on the insulating layer 6.

[0156] The configurations of the heating element 5, insulating layer 6, and heating element lead electrode 7 are the same as those of the above-described fusing member 3. That is, the heating element lead electrode 7 has a tip portion 7a extending between the heating elements 5, which is an area where the heating elements 5 are not formed, and a base portion 7b connecting to the heating element electrode 14.

[0157] The configuration and function of the heat dissipation section 8 are also similar to those of the above-described fusing member 3. The heat dissipation section 8 may be formed only on the insulating layer 6, or may be formed over as wide an area as possible, such as from the area overlapping with the heating element 5 to the side edge where the heating element power supply electrode 12 is formed (see FIGS. 2, 8, and 6). In the protective element 90, too, the heat dissipation section 8 is preferably covered with an insulating coating layer 17. In the protective element 90, too, the heat dissipation section 8 absorbs the heat from the heating element 5, thereby reducing uneven heat distribution on the insulating substrate 4 and suppressing damage (thermal shock cracking) to the insulating substrate 4 and the heating element 5 caused by localized concentration of heat from the heating element 5.

[0158] The fuse element 2 is connected to the first electrode 72, the second electrode 73, and the heating element extraction electrode 7 provided between the first electrode 72 and the second electrode 73 by a conductive connecting material such as connecting solder 9.

[0159] [Circuit configuration] 34 is a circuit diagram of the protection element 90 shown in FIG. 32. When the protection element 90 is used as a protection element for the battery pack 40 shown in FIG. 13, the first external connection electrode 74 is connected to the battery stack 45, and the second external connection electrode 75 is connected to the positive terminal 40a, thereby connecting the fuse element 2 in series to the charge / discharge path of the battery stack 45. In addition, in the protection element 90, the heating element 5 is connected to the current control element 48 via the heating element power supply electrode 12 and the third external connection electrode 76, and the heating element 5 is connected to an open end of the battery stack 45. As a result, one end of the heating element 5 is connected to the fuse element 2 and one open end of the battery stack 45 via the heating element lead-out electrode 7, and the other end is connected to the current control element 48 and the other open end of the battery stack 45 via the third external connection electrode 76, thereby forming a power supply path to the heating element 5, the current supply path to which is controlled by the current control element 48.

[0160] The connection between the protection element 90 and an external circuit such as a battery circuit can be achieved, for example, by mounting the fusing member 91 on an external circuit board by reflow mounting or the like. That is, the fusing member 91 is mounted on the external circuit board by placing the first to third external connection electrodes 74 to 76 formed on the back surface 4b of the insulating substrate 4 on lands provided at predetermined mounting positions on the external circuit board via a connecting material such as connecting solder, and passing through a reflow furnace. This allows the fuse element 2 to be incorporated into the current path of the external circuit.

[0161] [Protection element operation] When a current flows from an external circuit to the heating element 5 and the heating element 5 begins to generate heat, as shown in Figure 35, the heat generated by the heating element 5 causes the fuse element 2 to melt and cut off the current path of the external circuit. As shown in Figure 36, the molten conductor 2a of the fuse element 2 is held by the heating element lead electrode 7, and a portion of it is attracted into a through hole 11 opened in the heating element lead electrode 7 and held by a holding electrode 10 formed on the back surface 4b of the insulating substrate 4. Note that Figure 36(A) is a cross-sectional view taken along line A-A' in Figure 35(A), and Figure 36(B) is a cross-sectional view taken along line B-B' in Figure 35(A).

[0162] At this time, the heat dissipation portion 8 of the protective element 90 absorbs the heat from the heating element 5, thereby reducing uneven heat distribution on the insulating substrate 4 and suppressing damage (thermal shock cracks) to the insulating substrate 4 and the heating element 5 caused by localized concentration of heat from the heating element 5. Furthermore, the heat dissipation portion 8 formed between the heating element lead electrode 7 and the heating element power supply electrode 12 of the protective element 90 is electrically independent from the heating element lead electrode 7, so that the protective element 90 can suppress the occurrence of sparks (dielectric breakdown) between the heating element lead electrode 7 and the heating element power supply electrode 12. As a result, the protective element 90 can safely and quickly melt the fuse element 2 and interrupt the current path even when a high voltage is applied to the heating element 5.

[0163] When the fuse element 2 melts, the protective element 90 also cuts off the power supply path to the heating element 5, and the heating element 5 stops generating heat.

[0164] Even if an overcurrent exceeding the rated current flows through the fuse element 2, the protective element 90 melts due to self-heating of the fuse element 2, thereby cutting off the current path of the external circuit.

[0165] [Variation 5] In the above-described protection element 90, the first and second electrodes 72, 73 and the heating element lead electrode 7 are formed on the front surface 4a of the insulating substrate 4 on which the heating element 5 is formed, and the fuse element 2 is mounted, but the electrodes 72, 73 and the fuse element 2 may also be formed on the back surface 4b of the insulating substrate 4. In the following description, the same components as those in the above-described protection elements 1, 60, 70, 80, 90 are designated by the same reference numerals, and detailed descriptions thereof will be omitted.

[0166] 37 includes a fuse element 2 and a fusing member 97. As shown in FIG. 38, the fusing member 97 has a heating element power supply electrode 12, a heating element electrode 14, a heating element 5, an insulating layer 6, a heating element lead electrode 7, a first external connection electrode 74, a second external connection electrode 75, and a heat dissipation portion 8 formed on a surface 4a of an insulating substrate 4.

[0167] In addition, the protection element 96 has a first electrode 72, a second electrode 73, and a holding electrode 10 formed on the back surface 4b of the insulating substrate 4, and the fuse element 2 is mounted from the first electrode 72 through the holding electrode 10 to the second electrode 73. The holding electrode 10 is continuous with the heating element lead electrode 7 via a through hole 11.

[0168] The heater electrode 14 and the heater lead electrode 7 provided on the surface 4a of the insulating substrate 4 are electrically connected. Furthermore, the surface 4a of the insulating substrate 4 serves as the mounting surface for the protection element 96 to an external circuit board, and the heater power supply electrode 12, the first external connection electrode 74, and the second external connection electrode 75 are connected via connecting material such as connecting solder to lands provided at predetermined mounting positions on the external circuit board.

[0169] In the protective element 96, the heat dissipation section 8 is also formed electrically independent from the heat generating element lead electrode 7 in a region that overlaps at least with the heat generating element 5 via the insulating layer 6. The heat dissipation section 8 is provided away from the heat generating element lead electrode 7 and the first and second external connection electrodes 74, 75, and is therefore electrically independent from the power supply path to the heat generating element 5 and the current path of the external circuit.

[0170] In the protective element 96, the heat from the heating element 5 is also absorbed by the heat dissipation portion 8 formed to overlap the heating element 5. This reduces the unevenness of the heat distribution on the insulating substrate 4, and prevents damage (thermal shock cracks) to the insulating substrate 4 and the heating element 5 caused by the heat from the heating element 5 concentrating locally in an area where the heating element lead electrode 7 is not formed.

[0171] The protective element 96 may also be provided with an insulating coating layer 17 that insulates the heat dissipation portion 8. The heat dissipation portion 8 may be formed over as wide an area as possible, for example, from the area overlapping with the heating element 5 to an area where no electrodes such as the heating element power supply electrode 12 are formed. [Explanation of symbols]

[0172] 1 protective element, 2 fuse element, 2a melting conductor, 3 fusing member, 4 insulating substrate, 5 heating element, 6 insulating layer, 7 heating element lead electrode, 7a tip portion, 7b base portion, 8 heat dissipation portion, 9 connection solder, 10 holding electrode, 11 through hole, 12 heating element power supply electrode, 14 heating element electrode, 15 auxiliary electrode, 17 insulating coating layer, 20 screw hole, 21 first electrode terminal, 22 second electrode terminal, 23 third electrode terminal, 24 conductive layer, 26 low melting point metal layer, 27 high melting point metal layer, 28 case, 29 upper case, 30 lower case, 30a side edge portion, 30b hollow portion, 40 battery pack, 40a positive electrode terminal, 40b negative electrode terminal, 41 battery cell, 42 charging device, 43 current control element, 44 control unit, 45 Battery stack, 46 charge / discharge control circuit, 47 detection circuit, 48 current control element, 50 protrusion, 51 heat dissipation element, 60 protection element, 70 protection element, 71 fusing member, 72 first electrode, 73 second electrode, 74 first external connection electrode, 75 second external connection electrode, 76 third external connection electrode, 80 protection element, 81 fusing member, 82 second heat dissipation portion, 90 protection element, 91 fusing member, 96 protection element, 97 fusing member, 100 protection element, 101 fuse element, 102 fusing member, 103 insulating substrate, 104 heating element, 105 insulating layer, 106 heating element lead electrode, 107 holding electrode, 108 through hole, 109 auxiliary electrode, 110 heating element power supply electrode, 111 first electrode terminal, 112 Second electrode terminal, 114 connection solder

Claims

1. A fuse element and a fusing member that blows the fuse element, The fusing member is an insulating substrate; a heating element formed on the front surface side of the insulating substrate; an insulating layer covering the heating element; a heater lead electrode connected to the heater and overlapping the heater via the insulating layer; a heat dissipation section formed on the front surface of the insulating substrate in at least an area overlapping the heat generating element, and electrically independent from the heat generating element lead electrode; a holding electrode formed on a back surface of the insulating substrate opposite to the front surface, the holding electrode holding a molten conductor of the fuse element when the fuse element is blown; a through hole that connects the heating element extraction electrode and the holding electrode; The fuse element is connected to the holding electrode. Protection element.

2. A fuse element and a fusing member that blows the fuse element, The fusing member is an insulating substrate; a heating element formed on the front surface side of the insulating substrate; an insulating layer covering the heating element; a heater lead electrode connected to the heater and overlapping the heater via the insulating layer; a heat dissipation section formed on the front surface of the insulating substrate in at least an area overlapping the heat generating element, and electrically independent from the heat generating element lead electrode; a holding electrode formed on a back surface of the insulating substrate opposite to the front surface, the holding electrode holding a molten conductor of the fuse element when the fuse element is blown; a through hole that connects the heating element extraction electrode and the holding electrode; The fuse element is connected to the heating element lead electrode. Protection element.

3. a plurality of the fusing members; 3. The protection element according to claim 1, wherein the fusing member is connected to one surface of the fuse element and to another surface opposite to the one surface.

4. 4. The protection element according to claim 3, wherein the fusing members are provided at positions facing each other across the fuse element.

5. A fuse element and a fusing member that blows the fuse element, The fusing member is an insulating substrate; a heating element formed on the front surface side of the insulating substrate; an insulating layer covering the heating element; a heater lead electrode connected to the heater and overlapping the heater via the insulating layer; a heat dissipation section formed on the front surface of the insulating substrate in at least an area overlapping the heat generating element, and electrically independent from the heat generating element lead electrode; a first electrode and a second electrode formed on the surface of the insulating substrate and connected to an external circuit; The fuse element is connected to the first electrode, the second electrode, and the heating element lead electrode provided between the first electrode and the second electrode. Protection element.

6. 6. The protection element according to claim 5, wherein a plurality of the heating elements are provided in parallel on the front surface side of the insulating substrate.

7. a holding electrode formed on a back surface of the insulating substrate opposite to the front surface, the holding electrode holding a molten conductor of the fuse element when the fuse element is blown; 7. The protection element according to claim 6, further comprising a through-hole that penetrates through the region between the plurality of heating elements and connects the heating element lead electrode and the holding electrode.

8. A fuse element and a fusing member that blows the fuse element, The fusing member is an insulating substrate; a heating element formed on the front surface side of the insulating substrate; an insulating layer covering the heating element; a heater lead electrode formed on the rear surface of the insulating substrate so as to overlap the heater and connected to the heater; a heat dissipation portion formed on the rear surface of the insulating substrate in at least an area overlapping the heat generating element, and electrically independent from the heat generating element lead electrode; a first electrode and a second electrode formed on the back surface of the insulating substrate and connected to an external circuit; The fuse element is connected to the first electrode, the second electrode, and the heating element lead electrode. Protection element.

9. A fuse element and a fusing member that blows the fuse element, The fusing member is an insulating substrate; a plurality of heating elements arranged in parallel on the front surface side of the insulating substrate; an insulating layer covering the heating element; a heater lead electrode connected to the heater and overlapping the heater via the insulating layer; a heat dissipation section formed on the front surface of the insulating substrate in at least an area overlapping the heat generating element, and electrically independent from the heat generating element lead electrode; a first electrode and a second electrode formed on the back surface of the insulating substrate and connected to an external circuit; a holding electrode provided between the first electrode and the second electrode on the rear surface of the insulating substrate; a through-hole that penetrates the insulating substrate through a region between the plurality of heating elements and connects the heating element lead electrode and the holding electrode; The fuse element is connected to the first electrode, the second electrode, and the holding electrode. Protection element.

10. 10. The protection element according to claim 1, wherein the heat dissipation portion is made of a conductive material.

11. The protection element according to claim 10 , further comprising an insulating coating layer that covers the heat dissipation portion.

12. 10. The protection element according to claim 1, wherein the heat dissipation portion is formed over the surface and side surfaces of the insulating layer.

13. 13. The protection element according to claim 1, wherein the heat dissipation portion is formed over as wide an area as possible, covering an area overlapping the heat generating element and an area of ​​the insulating substrate where no electrodes are formed.

14. a case for accommodating the fusing member and the fuse element; 9. The protection element according to claim 1, wherein the case is formed with a protrusion that comes into contact with the heat dissipation portion and absorbs heat.

15. 9. The protection element according to claim 1, wherein the heat dissipation portion is provided with a heat dissipation element for diffusing heat from the heat dissipation portion.

16. 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 protective element is a protective element according to any one of claims 1 to 15. Battery pack.

Images