Protective components and battery packs

Abstract

The present invention provides a protection element that is difficult to generate sparks even when a high voltage is applied and can safely and quickly block the current path, and a battery pack using the same. It has an insulating substrate 2, a fuse element 3, a heating element 4 that melts the fuse element 3 by heating, a heating element power supply electrode 5 that serves as a power supply terminal for supplying power to the heating element 4, an insulating layer 6 that covers the heating element 4, and a heating element lead-out electrode 7 that is formed on the insulating layer 6 along the heating element 4 and holds the molten conductor 3a of the fuse element 3. If the heating element 4 is energized, the heating element power supply electrode 5 side becomes a high potential part and the heating element lead-out electrode 7 side becomes a low potential part. In the heating element lead-out electrode 7, the overlapping area of ​​the front end portion 7a extending on the high potential part side of the heating element 4 and the heating element 4 is smaller than the overlapping area of ​​the base portion 7b extending on the low potential part side of the heating element 4 and the heating element 4.

Description

Technical Field

[0001] The present technology relates to a protection element that protects a circuit connected to a current path by fusing the current path, and a battery pack using the same. This application claims priority based on Japanese patent application No. 2019-074956 filed in Japan on April 10, 2019, which is incorporated herein by reference. Background Art

[0002] Secondary batteries that can be repeatedly charged and used are mostly processed into battery packs and provided to users. In particular, in order to ensure the safety of users and electronic devices, multiple protection circuits such as overcharge protection and over-discharge protection are usually built into the battery pack to block the output of the battery pack under predetermined circumstances.

[0003] In most electronic devices using lithium-ion secondary batteries, the output is turned on / off using a FET switch built into the battery pack to perform overcharge protection or over-discharge protection of the battery pack. However, even if the FET switch is short-circuited and damaged for some reason, a large current flows instantaneously due to a lightning surge, or the output voltage drops abnormally due to the life of the battery cell or an excessive abnormal voltage is output, the battery pack and electronic equipment must be protected from accidents such as fire. In order to safely block the output of the battery cell in any conceivable abnormal state, a protection element including a fuse element is used, which has the function of blocking the current path by a signal from the outside.

[0004] As such a protection element for a protection circuit of a lithium ion secondary battery or the like, a structure is adopted in which a heating element is provided inside the protection element and a soluble conductor on a current path is melted by utilizing the heat generated by the heating element.

[0005] The use of lithium-ion secondary batteries has been expanding in recent years. There have been discussions about the use of higher currents, such as electric tools such as electric screwdrivers, hybrid vehicles, electric vehicles, electric-assisted bicycles and other transportation equipment, and some have already begun to use them. In these uses, especially during startup, there are situations where large currents exceeding 10A to 100A flow. It is expected to realize a protective element that can cope with such large current capacity.

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

[0007] Fig.25The figures show a configuration example of a conventional protection element, wherein (A) is a top view showing the structure without a covering member, (B) is a cross-sectional view, and (C) is a bottom view. Fig.25 The protection element 100 shown comprises: an insulating substrate 101, a first electrode 102 and a second electrode 103 formed on the surface of the insulating substrate 101, a heating element 104 formed on the surface of the insulating substrate 101, an insulating layer 105 covering the heating element 104, a heating element lead-out electrode 106 stacked on the insulating layer 105 and connected to the heating element 104, and a fuse element 107 mounted across the first electrode 102, the heating element lead-out electrode 106 and the second electrode 103 via a connecting solder.

[0008] The first electrode 102 and the second electrode 103 are terminal portions connected to the current path of the external circuit to which the protection element 100 is to be connected, and are respectively connected to the first external connection electrode 102a and the second external connection electrode 103a formed on the back side of the insulating substrate 101 via the castellations. In the protection element 100, the first external connection electrode 102a and the second external connection electrode 103a are connected to the connection electrodes provided on the external circuit substrate on which the protection element 100 is mounted, so that the fuse element 107 is incorporated into a part of the current path formed on the external circuit substrate.

[0009] The heating element 104 is a conductive component with a high resistance value that generates heat when electricity is supplied, and is made of, for example, nickel-chromium alloy, W, Mo, Ru, etc., or a material containing them. In addition, the heating element 104 is connected to a heating element power supply electrode 108 formed on the surface of the insulating substrate 101. The heating element power supply electrode 108 is connected to a third external connection electrode 108a formed on the back side of the insulating substrate 101 via a castellation. In the protection element 100, the heating element 104 is connected to an external power supply provided in an external circuit by connecting the third external connection electrode 108a to a connection electrode provided on an external circuit substrate on which the protection element 100 is mounted. In addition, the current and heat generation of the heating element 104 are always controlled by a switching element, etc., which are not shown in the figure.

[0010] The heating element 104 is covered with an insulating layer 105 made of a glass layer or the like, and a heating element lead-out electrode 106 is formed on the insulating layer 105, so that the heating element lead-out electrode 106 overlaps the insulating layer 105. In addition, a fuse element 107 is connected to the heating element lead-out electrode 106 so as to span between the first electrode 102 and the second electrode 103.

[0011] Thus, in the protection element 100 , the heating element 104 and the fuse element 107 are thermally connected by overlapping each other, and when the heating element 104 generates heat due to energization, the fuse element 107 can be melted.

[0012] The fuse element 107 is formed of a low melting point metal such as a Pb-free solder, a high melting point metal such as an alloy with these as the main component, or has a laminated structure of a low melting point metal and a high melting point metal. In addition, the fuse element 107 is connected from the first electrode 102 to the second electrode 103 across the heating element lead-out electrode 106, thereby constituting a part of the current path of the external circuit in which the protection element 100 is incorporated. In addition, the fuse element 107 is cut off due to self-heating (Joule heat) or due to the heating of the heating element 104 by passing electricity exceeding the rated current, thereby cutting off the first electrode 102 and the second electrode 103.

[0013] Furthermore, if the protection element 100 needs to block the current path of the external circuit, the heating element 104 is energized through the switch element. As a result, in the protection element 100, the heating element 104 generates heat at a high temperature, and the fuse element 107 incorporated in the current path of the external circuit is melted. The molten conductor of the fuse element 107 is attracted to the heating element lead-out electrode 106 and the first electrode 102 and the second electrode 103 with high wettability, so that the fuse element 107 is blown. As a result, the protection element 100 can fuse the first electrode 102, the heating element lead-out electrode 106, and the second electrode 103, thereby blocking the current path of the external circuit.

[0014] It should be noted that as a protection element, in addition to Fig.25 In addition to the structure shown, it is also proposed Fig.26 A protection element having two heating elements 104 as shown. Fig.26 The protection element 110 shown has two heating elements 104 arranged in parallel between a first electrode 102 and a second electrode 103 on the surface of an insulating substrate 101. Each heating element 104 is covered with an insulating layer 105, and a heating element extraction electrode 106 provided on the insulating layer 105 is formed in an overlapping manner so as to straddle the two heating elements 104.

[0015] in addition, Fig.26 In the protection element 110 shown, a collector 111 is formed on the back side of the insulating substrate 101, and a plurality of through holes 112 are provided that penetrate between the heating element lead-out electrode 106 and the collector 111. The collector 111 and the through holes 112 attract the molten conductor of the fuse element 107 melted on the heating element lead-out electrode 106, thereby increasing the holding capacity of the molten conductor of the fuse element 107 that has been enlarged for large current use, and a conductive layer is formed on the inner peripheral surface of the through hole 112.

[0016] Prior art literature

[0017] Patent Literature

[0018] Patent Document 1: Japanese Patent Publication No. 2018-78046 Summary of the invention

[0019] Problems to be solved by the invention

[0020] exist Fig.25 The protection element 100 shown, Fig.26 In a conventional structure such as the protection element 110 shown, in the case of a protection circuit for a lithium-ion secondary battery for large current use, the lithium-ion secondary battery for large current use is used as an external power source to supply power to the heating element 104, so a high voltage is applied to the heating element power supply electrode 108 when the protection element 100 is operating.

[0021] Therefore, in the protection element 100, if Fig. 27 As shown, there is a case where sparks (discharge) are generated from the heating element power supply electrode 108 to the front end of the heating element lead-out electrode 106, and the heating element lead-out electrode 106 is damaged. In addition, if the heating element lead-out electrode 106 is damaged, the thermal conductivity to the fuse element 107 is reduced at the damaged part, which prolongs the time until the fuse element 107 is melted, and there is a concern that the current path cannot be quickly and safely blocked.

[0022] In addition, if Fig.28 As shown, in the protection element 110, if a spark is generated from the heating element power supply electrode 108 to the front end of the heating element lead-out electrode 106 and the heating element lead-out electrode 106 is damaged, there is a concern that the thermal conductivity to the fuse element 107 at the damaged portion will decrease, prolonging the time until the fuse element 107 blows, and it may become impossible to quickly and safely block the current path. In addition, in order to efficiently transfer the heat of the heating element 104 to the heating element lead-out electrode 106 and the fuse element 107, the insulating layer (glass layer) 105 is formed to be as thin as 10 to 40 μm, and sometimes it may be damaged due to the heat of the heating element 104 being applied for a long time. In addition, as Fig.29 As shown, there is a concern that sparks may be generated from the high potential side of the heating element 104 to the central portion of the heating element lead-out electrode 106 at the damaged portion of the insulating layer 105. If the heating element lead-out electrode 106 is damaged, the thermal conductivity to the fuse element 107 may be reduced due to the damage to the insulating layer 105 and the damage to the heating element lead-out electrode 106, and the time until the fuse element 107 is blown may be extended, and the current path may not be blocked quickly and safely.

[0023] Since the electrode damage caused by such sparks results in incomplete melting of the fuse element, current interruption is hindered. Such risks increase with the size of the fuse element due to high voltage and large current, as the rated current increases and the electric field strength becomes higher, and further as the heating element power supply electrode 108 and the heating element lead-out electrode 106 are brought closer together and the insulating layer becomes thinner due to the miniaturization of the protection element.

[0024] Therefore, in a protection element having a built-in heating element, there is a demand for measures to cope with high voltage and high current while avoiding electrode destruction inside the element and operating more safely and quickly.

[0025] Here, an object of the present technology is to provide a protection element that is unlikely to generate sparks even when a high voltage is applied and can safely and quickly block a current path, and a battery pack using the same.

[0026] Methods for solving problems

[0027] In order to solve the above-mentioned problems, the protection element involved in the present technology comprises: an insulating substrate, a fuse element arranged on one side of the above-mentioned insulating substrate, a heating element formed on the above-mentioned insulating substrate and blowing out the above-mentioned fuse element by generating heat, a heating element power supply electrode connected to one end of the above-mentioned heating element and serving as a power supply terminal for supplying power to the above-mentioned heating element, an insulating layer covering the above-mentioned heating element, and a heating element lead-out electrode connected to the other end of the above-mentioned heating element, formed on the above-mentioned insulating layer along the above-mentioned heating element and serving as a molten conductor that holds the above-mentioned fuse element; if the above-mentioned heating element is energized via the above-mentioned heating element power supply electrode, the above-mentioned heating element power supply electrode side becomes a high potential portion, and the above-mentioned heating element lead-out electrode side becomes a low potential portion, and in the above-mentioned heating element lead-out electrode, the overlapping area between the front end portion extending on the high potential portion side of the above-mentioned heating element and the above-mentioned heating element is smaller than the overlapping area between the base portion extending on the low potential portion side of the above-mentioned heating element and the above-mentioned heating element.

[0028] In addition, the battery pack involved in the present technology comprises: one or more battery cells, a protection element connected to the charge and discharge path of the above-mentioned battery cells and blocking the charge and discharge path, and a current control element that detects the voltage value of the above-mentioned battery cells and controls the power supply to the above-mentioned protection element; the above-mentioned protection element comprises: an insulating substrate, a fuse element arranged on one side of the above-mentioned insulating substrate, a heating element formed on the above-mentioned insulating substrate and melting the above-mentioned fuse element by generating heat, a heating element power supply electrode connected to one end of the above-mentioned heating element and serving as a power supply terminal for supplying power to the above-mentioned heating element, and a heating element covered with a fuse element. The insulating layer of the heating element, and the heating element lead-out electrode connected to the other end of the heating element, formed on the insulating layer along the heating element and holding the molten conductor of the fuse element; if the heating element is energized via the heating element power supply electrode, the heating element power supply electrode side becomes the high potential part and the heating element lead-out electrode side becomes the low potential part, and in the heating element lead-out electrode, the overlapping area between the front end portion extending on the high potential part side of the heating element and the heating element is smaller than the overlapping area between the base portion extending on the low potential part side of the heating element and the heating element.

[0029] Effects of the Invention

[0030] According to the present technology, although the front end of the heating element lead-out electrode extends on the high potential part side of the heating element, the overlapping area with the heating element is smaller than the overlapping area between the base and the heating element. As a result, the distance and relative area (overlapping area) between the front end and the high potential part of the heating element are small, and accordingly, it is difficult to form a discharge path and generate sparks. As a result, it is difficult to generate sparks even when a high voltage is applied, and the current path can be safely and quickly blocked. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] [ Figure 1 ] Figure 1 The drawings show a first embodiment of a protection element to which the present technology is applied, wherein (A) is a top view, (B) is a cross-sectional view, and (C) is a bottom view.

[0032] [ Figure 2 ] Figure 2 The figures show how a fuse element in a protection element to which the present technology is applied is blown, wherein (A) is a plan view and (B) is a cross-sectional view.

[0033] [ Figure 3 ] Figure 3 The drawings show a modified example of the heat generating body lead-out electrode in the protection element to which the present technology is applied, wherein (A) is a top view and (B) is a cross-sectional view.

[0034] [ Figure 4 ] Figure 4 The drawings show a modified example of the heat generating body lead-out electrode in the protection element to which the present technology is applied, wherein (A) is a top view and (B) is a cross-sectional view.

[0035] [ Figure 5 ] Figure 5 This is a three-dimensional diagram of the appearance of a fuse element.

[0036] [ Figure 6 ] Figure 6 A circuit diagram showing an example of the configuration of a battery pack.

[0037] [ Figure 7 ] Figure 7 1 is a circuit diagram of a protection element according to the first embodiment.

[0038] [ Figure 8 ] Figure 8 The figures show a protection element according to a comparative example, wherein (A) is a top view, (B) is a cross-sectional view, and (C) is a bottom view.

[0039] [ Fig. 9 ] Fig. 9 It is a plan view showing a state in which the fuse element in the protection element according to the comparative example is not completely melted and is not blown.

[0040] [ Fig.10 ] Fig.10 The figures show a second embodiment of a protection element to which the present technology is applied, wherein (A) is a top view, (B) is a cross-sectional view, and (C) is a bottom view.

[0041] [ Fig.11 ] Fig.11 It is a plan view showing a modified example of the heat generating body lead-out electrode in the protection element according to the second embodiment.

[0042] [ Fig.12 ] Fig.12 2 is a circuit diagram of a protection element according to a second embodiment.

[0043] [ Fig.13 ] Fig.13 It is a plan view showing a modified example of the heat generating body lead-out electrode in the protection element according to the second embodiment.

[0044] [ Fig.14 ] Fig.14 It is a plan view showing a modified example of the heat generating body lead-out electrode in the protection element according to the second embodiment.

[0045] [ Fig.15 ] Fig.15 The figures show a modified example of a protection element according to the second embodiment in which a holding electrode for holding a fusible conductor of a fuse element is formed on the back surface of an insulating substrate. (A) is a top view, (B) is a cross-sectional view, and (C) is a bottom view.

[0046] [ Fig.16 ] Fig.16 To express Fig.15 The diagrams show a fuse element in a protection element that has been blown, wherein (A) is a top view and (B) is a cross-sectional view.

[0047] [ Fig.17 ] Fig.17 (A) to (D) are plan views showing modified examples of the heat generating element in the protection element according to the second embodiment.

[0048] [ Fig.18 ] Fig.18 The figures show a third embodiment of a protection element to which the present technology is applied, wherein (A) is a top view, (B) is a cross-sectional view, and (C) is a bottom view.

[0049] [ Fig.19 ] Fig.19 It is a cross-sectional view showing a state in which a fuse element is blown in the protection element according to the third embodiment.

[0050] [ Fig. 20 ] Fig. 20 This is a cross-sectional view showing a structure in which a fuse element is sandwiched between a plurality of fuse members.

[0051] [ Fig.21 ] Fig.21 for Fig. 20 The circuit diagram of the protection element is shown.

[0052] [ Fig. 22 ] Fig. 22 To express Fig. 20 A cross-sectional view showing a state in which a fuse element in a protection element is blown.

[0053] [ Fig.23 ] Fig.23 The figures show a protection element according to a comparative example, wherein (A) is a top view, (B) is a cross-sectional view, and (C) is a bottom view.

[0054] [ Fig.24 ] Fig.24 It is a plan view showing a state in which the fuse element in the protection element according to the comparative example is not completely melted and is not blown.

[0055] [ Fig.25 ] Fig.25 The figures show a conventional protection element, wherein (A) is a top view, (B) is a cross-sectional view, and (C) is a bottom view.

[0056] [ Fig.26 ] Fig.26 The figures show a conventional protection element, wherein (A) is a top view, (B) is a cross-sectional view, and (C) is a bottom view.

[0057] [ Fig. 27 ] Fig. 27 To express Fig.25 A top view showing a state in which a spark is generated in the protection element is shown.

[0058] [ Fig.28 ] Fig.28 To express Fig.26 A top view showing a state in which a spark is generated in the protection element is shown.

[0059] [ Fig.29 ] Fig.29 To express Fig.26 A top view showing a state in which a spark is generated in the protection element is shown.

[0060] The following describes a protection element and a battery pack to which the present technology is applied, while referring to the attached Figure 1 It is described in detail. It should be noted that the present technology is not limited to the following embodiments, and various changes can be made without departing from the main purpose of the present technology. In addition, the drawings are schematic, and the ratios of various dimensions are sometimes different from the actual situation. Specific dimensions should be determined by referring to the following description. In addition, of course, the drawings also contain parts with different dimensional relationships and ratios.

[0061] [First embodiment: Heat generating element overlapping structure]

[0062] A first embodiment of a protection element to which the present technology is applied is described. Figure 1 As shown in (A) to (C), a protection element 1 to which the present technology is applied comprises: an insulating substrate 2, a fuse element 3 arranged on the surface 2a side of the insulating substrate 2, a heating element 4 formed on the insulating substrate 2 and capable of blowing out the fuse element 3 by generating heat, a heating element power supply electrode 5 connected to one end of the heating element 4 and serving as a power supply terminal for supplying power to the heating element 4, an insulating layer 6 covering the heating element 4, and a heating element lead-out electrode 7 connected to the other end of the heating element 4, formed on the insulating layer 6 along the heating element 4 and holding the molten conductor 3a of the fuse element 3.

[0063] In addition, the feature is that when the heating element 4 is energized via the heating element power supply electrode 5, the heating element power supply electrode 5 side becomes a high potential portion, and the heating element lead-out electrode 7 side becomes a low potential portion. Furthermore, in the heating element lead-out electrode 7, the overlapping area between the front end portion 7a extending on the high potential portion side of the heating element 4 and the heating element 4 is smaller than the overlapping area between the base portion 7b extending on the low potential portion side of the heating element 4 and the heating element 4.

[0064] Therefore, the protection element 1 is less likely to generate sparks (discharge) even when a high voltage is applied, and can safely and quickly block the current path. This is considered to be due to the following reasons.

[0065] That is, sparks are a phenomenon in which a large current flows instantaneously from a high potential portion to a low potential portion due to insulation breakdown between electrodes facing each other through an insulating layer. In the heating element 4 connected to an external power source and to which a high voltage is applied, the end side connected to the heating element power supply electrode 5 becomes a higher potential than the other end side connected to the heating element lead-out electrode 7. Although the front end portion 7a of the heating element lead-out electrode 7 extends on the high potential portion side of the heating element 4, the overlapping area with the heating element 4 is smaller than the overlapping area between the base 7b and the heating element 4. As a result, the distance and relative area (overlapping area) between the front end portion 7a and the high potential portion of the heating element 4 are small, and accordingly, it is difficult to form a discharge path and generate sparks.

[0066] In addition, the overlapping area between the base 7b of the heating element lead-out electrode 7 and the heating element 4 is relatively larger, but since it is arranged at a position separated from the high potential portion of the heating element 4, and the other end side of the heating element 4 overlapping with the base 7b becomes a low potential portion due to a voltage drop, it is a portion where sparks are difficult to generate. Therefore, it is difficult for sparks to be generated at the base 7b.

[0067] By integrating such a protection element 1 into an external circuit, the fuse element 3 constitutes a part of the current path of the external circuit, and is melted by the heat of the heating element 4 or an overcurrent exceeding the rated value, thereby blocking the current path.

[0068] [Insulating substrate]

[0069] The insulating substrate 2 is formed of an insulating member such as alumina, glass ceramics, mullite, zirconia, etc. In addition, the insulating substrate 2 may be made of a material used in a printed wiring board such as a glass epoxy substrate or a phenolic substrate.

[0070] A first electrode 11 and a second electrode 12 are formed at two opposite ends of the insulating substrate 2. The first electrode 11 and the second electrode 12 are respectively formed of conductive patterns of Ag, Cu, etc. In addition, it is preferred that a Ni / Au plating layer, a Ni / Pd plating layer, a Ni / Pd / Au plating layer or the like is coated on the surface of the first electrode 11 and the second electrode 12 by a known method such as plating treatment. Thus, the protection element 1 can prevent oxidation of the first electrode 11 and the second electrode 12 and prevent rated changes caused by an increase in on-resistance. In addition, when the protection element 1 is reflow mounted, the first electrode 11 and the second electrode 12 can be prevented from being melted (solder corrosion) due to melting of the connection solder for connecting the fuse element 3.

[0071] In addition, the first electrode 11 and the second electrode 12 are connected to the first external connection electrode 11a and the second external connection electrode 12a formed on the back side 2b from the surface 2a of the insulating substrate 2 via the crenellations. In the protection element 1, the first external connection electrode 11a and the second external connection electrode 12a formed on the back side 2b of the insulating substrate 2 are connected to the connection electrodes provided on the external circuit substrate on which the protection element 1 is mounted, so that the fuse element 3 is incorporated into a part of the current path formed on the circuit substrate.

[0072] The first electrode 11 and the second electrode 12 are electrically connected by mounting the fuse element 3 using a conductive connection material such as a connection solder 9. Figure 2 As shown, a large current exceeding the rated value flows through the protection element 1, causing the fuse element 3 to melt due to self-heating (Joule heat), or the heating element 4 is heated by power supply, causing the fuse element 3 to melt, thereby blocking the first electrode 11 and the second electrode 12.

[0073] [Heat generating element]

[0074] The heating element 4 is a conductive member with a high resistance value that generates heat when electricity is applied, and is composed of, for example, nickel-chromium alloy, W, Mo, Ru, etc., or a material containing them. The heating element 4 can be formed by the following steps: mixing a powder of these alloys or compositions or compounds with a resin binder, etc. to form a paste, patterning the paste on the insulating substrate 2 using a screen printing technique, and sintering the paste.

[0075] In addition, one end of the heating element 4 is connected to the heating element power supply electrode 5, and the other end is connected to the heating element electrode 8. The heating element power supply electrode 5 and the heating element electrode 8 are formed on the side edges of the insulating substrate 2 that are different from the side edges where the first electrode 11 and the second electrode 12 are provided and are opposite to each other. The heating element power supply electrode 5 is an electrode that is connected to one end of the heating element 4 and serves as a power supply terminal for supplying power to the heating element 4, and is connected to the third external connection electrode 5a formed on the back surface 2b of the insulating substrate 2 via the castellations. The heating element lead-out electrode 7 is connected to the heating element electrode 8.

[0076] The heating element 4 is covered with an insulating layer 6 and overlaps with a heating element extraction electrode 7 formed on the insulating layer 6. The heating element extraction electrode 7 is connected to the fuse element 3 provided between the first electrode 11 and the second electrode 12 via a bonding material such as a connecting solder 9.

[0077] The insulating layer 6 is provided to protect and insulate the heating element 4 and to efficiently transfer the heat of the heating element 4 to the heating element lead-out electrode 7 and the fuse element 3, and is composed of, for example, a glass layer. In order to efficiently transfer the heat of the heating element 4 to the heating element lead-out electrode 7 and the fuse element 3, the thickness of the insulating layer 6 is formed to be thin, for example, 10 to 40 μm.

[0078] By mounting the protection element 1 on an external circuit substrate, the heating element 4 is connected to a current control element or the like formed in an external circuit via the third external connection electrode 5a, and the current and heat generation are normally limited. Furthermore, at a predetermined timing when the power-on path of the external circuit is blocked, the heating element 4 is energized via the third external connection electrode 5a to generate heat. At this time, the heating element power supply electrode 5 side of the heating element 4 becomes a high potential portion, and the heating element lead-out electrode 7 side becomes a low potential portion. In the protection element 1, the heat of the heating element 4 is transferred to the fuse element 3 via the insulating layer 6 and the heating element lead-out electrode 7, so that the fuse element 3 connecting the first electrode 11 and the second electrode 12 can be melted. The molten conductor 3a of the fuse element 3 condenses on the heating element lead-out electrode 7 and the first electrode 11 and the second electrode 12, thereby blocking the current path between the first electrode 11 and the second electrode 12. In addition, since the fuse element 3 is blown, the power-on path of the heating element 4 itself is also blocked, thereby stopping the heat generation.

[0079] It should be noted that the heating element power supply electrode 5 is preferably provided with a limiting wall 17, which prevents the connection solder provided on the electrode of the external circuit substrate connected to the third external connection electrode 5a from melting during reflow installation, climbing onto the heating element power supply electrode 5 via the castellations, and wetting and spreading on the heating element power supply electrode 5. The limiting wall 17 can be formed using an insulating material that does not have wettability to solder, such as glass, solder resist, and insulating adhesive, and can be formed on the heating element power supply electrode 5 by printing, etc. By providing the limiting wall 17, it is possible to prevent the molten connection solder from wetting and spreading to the heating element power supply electrode 5, thereby maintaining the connectivity between the protection element 1 and the external circuit substrate.

[0080] [Heat-generating element lead-out electrode]

[0081] The heating element lead-out electrode 7 is formed of a conductive pattern of Ag, Cu, etc., similarly to the first electrode 11 and the second electrode 12. In addition, the surface of the heating element lead-out electrode 7 is preferably coated with a film such as a Ni / Au plating, a Ni / Pd plating, or a Ni / Pd / Au plating by a known method such as plating treatment.

[0082] One end of the heating element lead-out electrode 7 is connected to the heating element electrode 8, and is formed on the insulating layer 6, overlapping with the heating element 4 via the insulating layer 6. As described above, the heating element lead-out electrode 7 has a front end portion 7a extending on the high potential portion side of the heating element 4 when energized and a base portion 7b extending on the low potential portion side, and an overlapping area S1 between the front end portion 7a and the heating element 4 is smaller than an overlapping area S2 between the base portion 7b and the heating element 4. Thus, the protection element 1 is unlikely to generate sparks (discharge) even when a high voltage is applied through an external circuit, and can safely and quickly block the current path.

[0083] Here, in the protection element 1, when the direction perpendicular to the direction of conduction of the heating element 4 is set as the width direction, the heating element extraction electrode 7 has a wide width portion provided on the low potential portion side, and a narrow width portion provided on the high potential portion side and protruding from the wide width portion, the wide width portion is defined as the base 7b, and the narrow width portion protruding from the base 7b is defined as the front end portion 7a. In addition, in the heating element extraction electrode 7, the overlapping area S1 of the front end portion 7a and the heating element 4 is smaller than the overlapping area S2 of the base 7b and the heating element 4.

[0084] Therefore, if Figure 1 As shown, even when the entire tip portion 7a overlaps the heating element 4, the protection element 1 is unlikely to generate sparks (discharge) when a high voltage is applied via an external circuit, and can safely and quickly block the current path.

[0085] In addition, by providing a wide base portion 7b on the heating element lead-out electrode 7, the capacity of the molten conductor 3a holding the fuse element 3 can be increased, and the fuse element 3 can be effectively blown. That is, in the heating element lead-out electrode 7, sparks can be prevented by providing a narrow front end portion 7a, but on the other hand, if the area of ​​the heating element lead-out electrode 7 is reduced, the capacity of the molten conductor 3a is reduced when the fuse element 3 is melted, and the molten conductor 3a overflowing from the heating element lead-out electrode 7 contacts the molten conductor 3a on the first electrode 11 and the second electrode 12, and there is a concern that the current path cannot be blocked. In this regard, the heating element lead-out electrode 7 can increase the capacity of the molten conductor 3a by forming a wide base portion 7b, and the fuse element 3 can be effectively blown ( Figure 2 ).

[0086] In addition, in the protection element 1, as Figure 1 As shown, in the assumed region when the tip portion 7a of the heat generating body lead-out electrode 7 has the same width as the base portion 7b, the overlapping area S1 with the heat generating body 4 is preferably narrower than the non-overlapping area S3 with the heat generating body in the assumed region. Figure 1 In the protection element 1 shown, the non-overlapping area S3 in the assumed region refers to the total area of ​​both sides of the front end portion 7a.

[0087] In this assumed region, the overlapping area S1 between the tip portion 7a and the high potential portion of the heating element 4 is set smaller than the non-overlapping area S3 with the high potential portion, thereby making it difficult to form a discharge path and generate sparks.

[0088] In addition, in the heating element lead-out electrode 7, Figure 1 As shown, the area of ​​the front end portion 7a is preferably smaller than the area of ​​the base portion 7b. Thus, even when the entire front end portion 7a overlaps with the heating element 4, the protection element 1 is unlikely to generate sparks (discharges) when a high voltage is applied via an external circuit, and the current path can be safely and quickly blocked.

[0089] Figure 3 , Figure 4 This is a modified example of the heating element lead-out electrode 7. In the heating element lead-out electrode 7, the front end portion 7a may be formed into a substantially trapezoidal shape or a triangular shape. Figure 3 , Figure 4 In the figure, the fuse element 3 is omitted.

[0090] In addition, if Figure 1As shown, the fuse element 3 is mounted on the heating element lead-out electrode 7, and the front end portion 7a of the heating element lead-out electrode 7 preferably does not protrude toward the heating element power supply electrode 5 side compared with the side edge of the fuse element 3. Since the heating element power supply electrode 5 is applied with a high voltage and becomes a high potential, the heating element lead-out electrode 7 is withdrawn from the fuse element 3 to the low potential portion side, thereby separating the heating element lead-out electrode 7 from the high potential portion. In addition, if the front end portion 7a of the heating element lead-out electrode 7 protrudes toward the heating element power supply electrode 5 side compared with the side edge of the fuse element 3, there is a concern that the front end portion 7a acts as a lightning rod, but such a lightning rod-like portion is not formed, and the risk of spark generation can be reduced. Furthermore, by overlapping the heating element lead-out electrode 7 with the fuse element 3, the volume of the metal (i.e., the front end portion 7a and the fuse element 3) facing the heating element power supply electrode 5 that becomes a high potential is increased, and even when sparks are generated, the resistance to impact is improved to prevent damage.

[0091] [Fuse element]

[0092] Next, the fuse element 3 is described. The fuse element 3 is installed across the first electrode 11 and the second electrode 12, and is melted due to the heat generated by the energization of the heating element 4, or melted due to self-heating (Joule heat) caused by the flow of current exceeding the rated value, thereby blocking the current path between the first electrode 11 and the second electrode 12.

[0093] The fuse element 3 can be made of any conductive material that melts due to the heat generated by the power supply to the heating element 4 or due to an overcurrent condition. For example, in addition to SnAgCu-based Pb-free solder, BiPbSn alloy, BiPb alloy, BiSn alloy, SnPb alloy, PbIn alloy, ZnAl alloy, InSn alloy, PbAgSn alloy, etc. can also be used.

[0094] In addition, the fuse element 3 may be a structure containing a high melting point metal and a low melting point metal. Figure 5 As shown, the fuse element 3 is a laminated structure consisting of an inner layer and an outer layer, and has a low melting point metal layer 13 as an inner layer, and a high melting point metal layer 14 as an outer layer laminated on the low melting point metal layer 13. The fuse element 3 is connected to the first electrode 11, the second electrode 12 and the heating element lead-out electrode 7 via a bonding material such as a connecting solder 9.

[0095] The low melting point metal layer 13 is preferably solder or a metal with Sn as the main component, which is a material generally referred to as "Pb-free solder". The melting point of the low melting point metal layer 13 does not necessarily have to be higher than the temperature of the reflow furnace, and can melt at around 200°C. The high melting point metal layer 14 is a metal layer stacked on the surface of the low melting point metal layer 13, such as Ag or Cu or a metal with any of them as the main component, and has a high melting point that does not melt when the first electrode 11, the second electrode 12 and the heating element lead-out electrode 7 are connected to the fuse element 3 by reflow soldering, and the protection element 1 is installed on the external circuit substrate.

[0096] Such a fuse element 3 can be formed by forming a high melting point metal layer on a low melting point metal foil by using a plating technique, or can be formed by using other well-known lamination techniques or film formation techniques. In this case, the fuse element 3 can be a structure in which the entire surface of the low melting point metal layer 13 is covered by the high melting point metal layer 14, or a structure in which the low melting point metal layer 13 is covered except for a pair of opposite side surfaces. It should be noted that the fuse element 3 can also be composed of the high melting point metal layer 14 as the inner layer and the low melting point metal layer 13 as the outer layer, and can also be formed into a multilayer structure of more than three layers in which the low melting point metal layer and the high melting point metal layer are alternately stacked, and a part of the outer layer is provided with an opening to expose a part of the inner layer, etc.

[0097] The fuse element 3 is formed by stacking a high melting point metal layer 14 as an outer layer on a low melting point metal layer 13 as an inner layer, so that even when the reflow soldering temperature exceeds the melting temperature of the low melting point metal layer 13, the fuse element 3 can maintain its shape and not be blown. Therefore, the first electrode 11, the second electrode 12 and the heating element lead-out electrode 7 can be efficiently connected to the fuse element 3 and the protection element 1 can be mounted on an external circuit substrate by reflow soldering. In addition, the deformation of the fuse element 3 caused by reflow soldering can be prevented from causing a local increase or decrease in resistance value, thereby preventing the fuse element 3 from not blowing at a predetermined temperature or blowing at a temperature lower than a predetermined temperature, and other changes in the blowing characteristics.

[0098] In addition, the fuse element 3 will not be blown due to self-heating during the period when the predetermined rated current flows. If the current higher than the rated value flows, it will melt due to self-heating, thereby blocking the current path between the first electrode 11 and the second electrode 12. In addition, the heating element 4 is energized and generates heat to melt, thereby blocking the current path between the first electrode 11 and the second electrode 12.

[0099] At this time, in the fuse element 3, the molten low melting point metal layer 13 corrodes (solder corrodes) the high melting point metal layer 14, so that the high melting point metal layer 14 is dissolved at a temperature lower than the melting temperature. Therefore, the fuse element 3 can be fused in a short time by utilizing the corrosive effect of the low melting point metal layer 13 on the high melting point metal layer 14. In addition, the molten conductor 3a of the fuse element 3 is separated by the physical attraction between the heating element lead-out electrode 7 and the first electrode 11 and the second electrode 12, so that the current path between the first electrode 11 and the second electrode 12 can be quickly and reliably blocked ( Figure 2 ).

[0100] In addition, in the fuse element 3, it is preferred that the volume of the low melting point metal layer 13 is formed to be larger than the volume of the high melting point metal layer 14. The fuse element 3 is heated by self-heating caused by overcurrent or heating of the heating element 4, and the low melting point metal melts, thereby corroding the high melting point metal, thereby being able to melt and blow quickly. Therefore, the fuse element 3 can quickly block the first external connection electrode 11 and the second external connection electrode 12 by forming the volume of the low melting point metal layer 13 to be larger than the volume of the high melting point metal layer 14, thereby promoting the corrosion effect.

[0101] In addition, since the fuse element 3 is formed by stacking a high melting point metal layer 14 on a low melting point metal layer 13 as an inner layer, the fusing temperature can be greatly reduced compared to conventional chip fuses made of high melting point metals. Therefore, the fuse element 3 can have a larger cross-sectional area and a significantly higher rated current than chip fuses of the same size. In addition, compared to conventional chip fuses with the same rated current, it can be miniaturized and thinned, and has excellent rapid fusing properties.

[0102] In addition, the fuse element 3 can improve the resistance (pulse resistance) to the surge of abnormally high voltage applied instantaneously to the electrical system in which the protection element 1 is incorporated. That is, the fuse element 3 cannot be blown when a current of, for example, 100A flows for a few milliseconds. In this regard, since a large current flowing in a very short time will flow through the surface layer of the conductor (skin effect), the fuse element 3 is provided with a high melting point metal layer 14 such as an Ag plating layer with a low resistance value as an outer layer, so that the current applied by the surge can easily flow through, and can prevent the melting caused by self-heating. Therefore, compared with the conventional fuse composed of solder alloy, the fuse element 3 can greatly improve the resistance to surges.

[0103] It should be noted that the fuse element 3 may also be coated with flux (not shown) for the purpose of anti-oxidation and improving wettability during melting. In addition, the protection element 1 is covered by a shell member (not shown) through the insulating substrate 3 so that its interior is protected. The shell member can be formed using insulating members such as various engineering plastics, thermoplastics, ceramics, glass epoxy substrates, etc. In addition, the shell has an internal space sufficient to allow the fuse element 3 to expand in a spherical shape on the surface 2a of the insulating substrate 2 when it is melted, and the molten conductor 3a condenses on the heating element lead-out electrode 7, the first electrode 11, and the second electrode 12.

[0104] [Circuit Configuration Example]

[0105] like Figure 6 As shown, such a protection element 1 is used by being incorporated in a circuit in a lithium ion secondary battery pack 20. The battery pack 20 has a battery stack 25 composed of, for example, four lithium ion secondary battery cells 21a to 21d in total.

[0106] The battery pack 20 includes: a battery stack 25, a charge and discharge control circuit 26 for controlling the charge and discharge of the battery stack 25, a protection element 1 applying the present invention for blocking the charge and discharge path when the battery stack 25 is abnormal, a detection circuit 27 for detecting the voltage of each battery cell 21a~21d, and a current control element 28 as a switching element that controls the operation of the protection element 1 according to the detection result of the detection circuit 27.

[0107] The battery stack 25 is formed by connecting battery cells 21a to 21d in series, which need to be controlled to protect against overcharge and overdischarge, and is detachably connected to a charging device 22 via a positive terminal 20a and a negative terminal 20b of the battery pack 20, and a charging voltage is applied from the charging device 22. The battery pack 20 charged by the charging device 22 can be operated by connecting the positive terminal 20a and the negative terminal 20b to an electronic device that operates on a battery.

[0108] The charge and discharge control circuit 26 includes two current control elements 23a and 23b connected in series on the current path between the battery stack 25 and the charging device 22, and a control unit 24 that controls the operation of these current control elements 23a and 23b. The current control elements 23a and 23b are composed of, for example, field effect transistors (hereinafter referred to as FETs), and the control unit 24 controls the gate voltage to control the conduction and blocking of the battery stack 25 in the charging direction and / or the discharging direction of the current path. The control unit 24 operates by receiving power supply from the charging device 22, and controls the operation of the current control elements 23a and 23b according to the detection result of the detection circuit 27 so that the current path is blocked when the battery stack 25 is over-discharged or over-charged.

[0109] The protection element 1 is connected to, for example, a charge and discharge current path between the battery stack 25 and the charge and discharge control circuit 26 , and its operation is controlled by a current control element 28 .

[0110] The detection circuit 27 is connected to each battery cell 21a to 21d, detects the voltage value of each battery cell 21a to 21d, and provides each voltage value to the control unit 24 of the charge and discharge control circuit 26. In addition, the detection circuit 27 outputs a control signal for controlling the current control element 28 when any battery cell 21a to 21d reaches an overcharge voltage or an overdischarge voltage.

[0111] The current control element 28 is composed of, for example, a FET and is controlled as follows: based on the detection signal output from the detection circuit 27, when the voltage value of the battery cells 21a~21d becomes a voltage exceeding a predetermined over-discharge or over-charge state, the protection element 1 is activated to control the charge and discharge current path of the battery stack 25 by blocking it regardless of whether the switches of the current control elements 23a and 23b are operating or not.

[0112] The protection element 1 to which the present invention is applied and used in the battery pack 20 having the above-mentioned structure has the following features: Figure 7 The circuit configuration is as shown. That is, in the protection element 1, the first external connection electrode 11a is connected to the battery stack 25 side, and the second external connection electrode 12a is connected to the positive terminal 20a side, thereby, the fuse element 3 is connected in series to the charge and discharge path of the battery stack 25. In addition, in the protection element 1, the heating element 4 is connected to the current control element 28 via the heating element power supply electrode 5 and the third external connection electrode 5a, and the heating element 4 is connected to the open end of the battery stack 25. Thus, one end of the heating element 4 is connected to the fuse element 3 and one open end of the battery stack 25 via the heating element lead-out electrode 7, and the other end is connected to the current control element 28 and the other open end of the battery stack 25 via the third external connection electrode 5a, forming a power supply path to the heating element 4 controlled by the current control element 28.

[0113] [Operation of protection element]

[0114] When the detection circuit 27 detects an abnormal voltage in any of the battery cells 21a to 21d, it outputs a blocking signal to the current control element 28. Then, the current control element 28 controls the current to energize the heating element 4. In the protection element 1, the current flows from the battery stack 25 into the heating element 4, so that the heating element 4 starts to generate heat. In the protection element 1, due to the heat generated by the heating element 4, the fuse element 3 melts, blocking the charge and discharge path of the battery stack 25. In addition, in the protection element 1, the fuse element 3 is formed by 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 fuse element 3 can be dissolved in a short time by utilizing the corrosion effect of the molten low melting point metal on the high melting point metal.

[0115] At this time, in the protection element 1, the overlapping area S1 of the front end portion 7a extending on the high potential portion side of the heating element 4 and the heating element 4 when energized is set to be smaller than the overlapping area S2 of the base portion 7b extending on the low potential portion side and the heating element 4. Thus, even when a high voltage is applied to the heating element power supply electrode 5 through the battery stack 25 for large current use, the protection element 1 is unlikely to generate sparks (discharge) and can safely and quickly block the current path.

[0116] In addition, the protection element 1 has a narrow front end portion 7a protruding from the base 7b of the heating element lead-out electrode 7, so that the heat of the heating element 4 is concentrated on the front end portion 7a, and the high heat can be quickly transferred from the front end portion 7a to the fuse element 3. That is, the protection element 1 has a narrow front end portion 7a, so that the heat of the heating element 4 is not diffused but concentrated on the front end portion 7a compared to the rectangular heating element lead-out electrode, and can be efficiently transferred to the fuse element 3. Therefore, even if the cross-sectional area of ​​the fuse element 3 is increased to cope with high current applications, the protection element 1 can concentrate the heat on the front end portion 7a and quickly blow the fuse element 3.

[0117] In the protection element 1 , the fuse element 3 is melted, so that the power supply path to the heating element 4 is also blocked, and thus the heating of the heating element 4 stops.

[0118] It should be noted that, in the protection element 1 , even when an overcurrent exceeding the rated value flows into the battery pack 20 , the fuse element 3 melts due to self-heating, thereby blocking the charge and discharge path of the battery pack 20 .

[0119] In this way, in the protection element 1, the fuse element 3 is melted due to the heat generated by the energization of the heating element 4 or the self-heating of the fuse element 3 due to the overcurrent. At this time, in the protection element 1, even when the circuit substrate on which the protection element 1 is mounted is further exposed to a high temperature environment such as reflow heating during reflow mounting on the circuit substrate, the deformation of the fuse element 3 is suppressed due to the structure in which the low melting point metal is covered by the high melting point metal. Therefore, the change in the fusing characteristics caused by the change in the resistance value due to the deformation of the fuse element 3 can be prevented, and the fuse element 3 is quickly melted by the predetermined overcurrent and the heat generated by the heating element 4.

[0120] The protection element 1 according to the present invention is not limited to the case of being used in a battery pack of a lithium ion secondary battery, and can of course be applied to various uses that require blocking a current path using an electric signal.

[0121] First embodiment

[0122] Next, an embodiment of the protection element 1 is described. In the first embodiment, a Figure 1 The protection element 1 shown and provided with Fig.25 and Figure 8 The rectangular heating element lead-out electrode protection element shown in the figure determines whether there is spark when voltages of 50 V, 100 V, and 200 V are applied. In addition, the melting time of the fuse element is evaluated, and the case of melting within the predetermined time (60 seconds) is evaluated as ○ (good), and the case of not melting within the predetermined time is evaluated as × (bad).

[0123] The dimensions of each part of the protection element according to the embodiment and the comparative example are defined as follows: The numerical values ​​of each part shown in Table 1 are numerical values ​​indicating a ratio when E is set to 1.

[0124] D: The distance between the front end of the heating element lead-out electrode and the heating element power supply electrode

[0125] E: Length of the heating element in the direction of current flow

[0126] F: Minimum width of the heating element lead electrode

[0127] G: Maximum width of the heating element lead-out electrode

[0128] L: The width between the side edge of the front end of the heating element lead-out electrode and the side edge of the base

[0129] P: The overlapping length between the heating element lead-out electrode and the heating element

[0130] Q: The length of the base of the heating element lead electrode

[0131] [Table 1]

[0132]

[0133] [Example 1]

[0134] The protection element involved in Example 1 adopts Figure 1 The protection element shown. In the protection element involved in Example 1, a base (width G: 0.33) and a front end (width F: 0.1) are provided on the heating element lead-out electrode, and the base is formed to be 0.06 wider on one side than the front end. In addition, the heating element lead-out electrode does not protrude toward the heating element power supply electrode side compared to the fuse element, and the distance D between the front end of the heating element lead-out electrode and the heating element power supply electrode is ensured to be 0.38, and the overlapping length P of the heating element lead-out electrode and the heating element is set to 0.62.

[0135] [Comparative Example 1]

[0136] The protection element used in Comparative Example 1 Fig.25 The protection element shown. In the protection element involved in Comparative Example 1, a rectangular heating element lead-out electrode (width: 0.21) is formed. In addition, the heating element lead-out electrode protrudes toward the heating element power supply electrode side compared with the fuse element, and the distance D between the front end of the heating element lead-out electrode and the heating element power supply electrode is as short as 0.07, and the overlapping length P of the heating element lead-out electrode and the heating element is set to 0.93.

[0137] [Comparative Example 2]

[0138] The protective element used in Comparative Example 2 Figure 8 The protection element shown. Similar to Comparative Example 1, the protection element involved in Comparative Example 2 also uses a rectangular heating element lead-out electrode (width: 0.21). The difference from Comparative Example 1 is that in the protection element involved in Comparative Example 2, the heating element lead-out electrode does not protrude toward the heating element power supply electrode side compared to the fuse element. Therefore, in Comparative Example 2, the distance D between the front end of the heating element lead-out electrode and the heating element power supply electrode is ensured to be 0.38, and the overlapping length P of the heating element lead-out electrode and the heating element is set to 0.62.

[0139] [Table 2]

[0140]

[0141] As shown in Table 2, in Example 1, no sparks were generated when any voltage was applied, and the fuse element was able to be melted within the predetermined time. On the other hand, in Comparative Example 1, sparks were generated when any voltage was applied, but the fuse element was not able to be melted within the predetermined time. In addition, in Comparative Example 2, no sparks were generated when any voltage was applied, but since a narrow rectangular heating element lead-out electrode with a width of 0.21 was used, the capacity of the molten conductor of the fuse element was insufficient, as shown in FIG. Fig. 9As shown, the molten conductor is connected between the first electrode and the second electrode, and the fuse element cannot be melted within a predetermined time.

[0142] [Second embodiment: structure on both sides of the surface heating element]

[0143] Next, a second embodiment of a protection element to which the present technology is applied is described. It should be noted that in the following description, the same reference numerals are sometimes assigned to the same components as those of the protection element 1, and their detailed description is omitted. Fig.10 As shown in (A) to (C), the protection element 30 involved in the second embodiment comprises: an insulating substrate 2, a fuse element 3 arranged on the surface 2a side of the insulating substrate 2, a plurality of heating elements 4 formed on the insulating substrate 2 and capable of blowing out the fuse element 3 by generating heat, a heating element power supply electrode 5 connected to one end of the heating element 4 and serving as a power supply terminal for supplying power to the heating element 4, an insulating layer 6 covering the heating element 4, and a heating element lead-out electrode 7 connected to the other end of the heating element 4, formed on the insulating layer 6 along the heating element 4 and holding the molten conductor 3a of the fuse element 3.

[0144] Furthermore, in the protection element 30, a plurality of heating elements 4 are separated and arranged in parallel on the insulating substrate 2. One end of each heating element 4 is connected to the heating element power supply electrode 5, and the other end is connected to the heating element electrode 8. The heating element electrode 8 is connected to the heating element lead-out electrode 7. When each heating element 4 is energized via the heating element power supply electrode 5, the heating element power supply electrode 5 side becomes a high potential portion, and the heating element electrode 8 and the heating element lead-out electrode 7 side become low potential portions. In addition, each heating element 4 is covered by an insulating layer 6 and overlaps with the heating element lead-out electrode 7 formed on the insulating layer 6.

[0145] The heat generating body lead-out electrode 7 formed on the protection element 30 can be formed by a known method such as printing using a known electrode material such as Ag, Cu, or an alloy material mainly composed of Ag or Cu.

[0146] The heating element lead-out electrode 7 has a front end portion 7a extending on the high potential portion side of each heating element 4 when energized and a base portion 7b extending on the low potential portion side, and an overlapping area S1 between the front end portion 7a and the heating element 4 is smaller than an overlapping area S2 between the base portion 7b and the heating element 4. Thus, the protection element 30 is similar to the protection element 1 in that it is difficult to generate sparks (discharge) even when a high voltage is applied through an external circuit, and the current path can be safely and quickly blocked.

[0147] in addition, Fig.10In the protection element 30 shown, the heating element lead-out electrode 7 overlaps with each heating element 4 at the base 7b, and the front end portion 7a is formed in the area between the two heating elements 4, and the front end portion 7a does not overlap with the two heating elements 4. Although the front end portion 7a of the heating element lead-out electrode 7 extends on the high potential portion side of the heating element 4, the overlapping area with the heating element 4 is non-overlapping, that is, the overlapping area with the heating element 4 is zero, which is smaller than the overlapping area of ​​the base 7b with the heating element 4. As a result, the distance and relative area (overlapping area) between the front end portion 7a and the high potential portion of the heating element 4 are small, and accordingly, it is difficult to form a discharge path and generate sparks.

[0148] It should be noted that the protection element 30 may also be Fig.11 As shown, the front end portion 7 a of the heat generating element lead-out electrode 7 is formed in a region between two heat generating elements 4 , and a portion of the front end portion 7 a overlaps at least one, preferably two, of the heat generating elements 4 . Fig.11 In the structure shown, in the protection element 30, the overlapping area S1 of the front end portion 7a and the heating element 4 is also smaller than the overlapping area S2 of the base portion 7b and the heating element 4, so that it is difficult to generate sparks (discharge) even when a high voltage is applied, and the current path can be safely and quickly blocked. In addition, by partially overlapping the front end portion 7a and the heating element 4, the heat of the heating element 4 is efficiently transferred to the front end portion 7a, and the fuse element 3 can be heated more quickly.

[0149] Fig.12 3 is a circuit diagram of the protection element 30. In the protection element 30, one end of each of the plurality of heating elements 4 is connected to a power source for generating heat via a heating element power supply electrode 5 formed on the insulating substrate 2, and the other end of each heating element 4 is connected to the fuse element 3 via a heating element lead-out electrode 7.

[0150] [Modification of Heat Generator Lead-out Electrode 7]

[0151] Fig.13 , Fig.14 FIG. 7 is a modified example of the heating element lead-out electrode 7. Fig.13 As shown in FIG. 1 , the heating element lead-out electrode 7 has a front end portion 7a formed into a rectangular shape, and the front end portion 7a is connected to the base portion 7b via an inclined surface. Fig.14 The front end portion 7a is formed in a substantially trapezoidal shape or in a triangular shape.

[0152] In addition, the protection element 30 may also be Fig.15 As shown, a holding electrode 32 for holding the molten conductor 3a of the fuse element 3 is formed on the back side 2b of the insulating substrate 2, the heating element lead-out electrode 7 is connected to the holding electrode 32 via a through hole 33 penetrating the insulating substrate 2, and the molten conductor 3a of the molten fuse element 3 is attracted to the holding electrode 32 side via the through hole 33.

[0153] When the fuse element 3 melts, the through hole 33 attracts the molten conductor 3a by the capillary phenomenon, and the volume of the molten conductor 3a held on the heating element lead-out electrode 7 can be reduced. Fig.16 As shown, even if the fuse element 3 becomes larger due to the higher rating and higher capacity of the protection element, resulting in an increase in the melting amount, the holding electrode 32, the heating element lead-out electrode 7 and the first electrode 11 and the second electrode 12 can be used to hold a large amount of molten conductor 3a, so that the fuse element 3 can be effectively blown.

[0154] Similar to the heat generating body lead-out electrode 7 , the holding electrode 32 can be formed by a known method such as printing using a known electrode material such as Ag, Cu, or an alloy material mainly composed of Ag or Cu.

[0155] A conductive layer 34 is formed on the inner surface of the through hole 33. By forming the conductive layer 34, the through hole 33 can easily attract the molten conductor 3a. The conductive layer 34 is formed of, for example, any one of copper, silver, gold, iron, nickel, palladium, lead, and tin, or an alloy containing any one of them as a main component, and the inner surface of the through hole 33 can be formed by a known method such as electroplating and conductive paste printing. In addition, the conductive layer 34 can be formed by inserting a plurality of metal wires or a collection of conductive strip wires into the through hole 33.

[0156] The conductive layer 34 of the through hole 33 is connected to the heating element lead-out electrode 7 formed on the surface 2a of the insulating substrate 2. The heating element lead-out electrode 7 supports the fuse element 3, and the molten conductor 3a will condense when it is blown, so the heating element lead-out electrode 7 is connected to the conductive layer 34, so that the molten conductor 3a can be easily introduced into the through hole 33.

[0157] In addition, the conductive layer 34 of the through hole 33 is connected to the holding electrode 32 formed on the back surface 2b of the insulating substrate 2. Therefore, when the fuse element 3 melts, the molten conductor 3a attracted through the through hole 33 can be condensed on the holding electrode 32 (see Fig.16 ), attracting more molten conductors 3a, can reduce the volume of the molten conductor 3a at the blown portion of the fuse element 3 held by the heating element lead-out electrode 7 and the first electrode 11 and the second electrode 12.

[0158] It should be noted that in the protection element 30, a plurality of through holes 33 may be formed to increase the paths for attracting the molten conductor 3a of the fuse element 3, thereby attracting more molten conductors 3a and reducing the volume of the molten conductor 3a at the blown portion.

[0159] [Modification of the heating element]

[0160] It should be noted that the protection element 30 may be formed into a substantially rectangular shape in addition to the plurality of heating elements 4. Fig.17 As shown in FIG. 1 , the protrusion 4a is formed in an L-shaped end portion on the low potential portion side, and the protrusions 4a are made to face each other. The protrusion 4a can be formed as follows. Fig.17 (A) (B) is formed in a manner substantially perpendicular to the long side direction of the heating element 4, or as shown in Fig.17 (C) and (D) show a tapered surface. In addition, the heat generating body lead-out electrode 7 or the holding electrode 32 may overlap with the protruding portion 4a.

[0161] [Third embodiment: rear heating element structure]

[0162] Next, a third embodiment of a protection element to which the present technology is applied will be described. It should be noted that in the following description, the same reference numerals may be assigned to the same components as those of the above-mentioned protection elements 1 and 30, and their detailed description may be omitted. Fig.18 As shown in (A)(B), the protection element 40 involved in the third embodiment comprises: an insulating substrate 2, a fuse element 3 arranged on the surface 2a side of the insulating substrate 2, a plurality of heating elements 4 formed on the insulating substrate 2 and capable of blowing out the fuse element 3 by generating heat, a heating element power supply electrode 5 connected to one end of the heating element 4 and serving as a power supply terminal for supplying power to the heating element 4, an insulating layer 6 covering the heating element 4, and a heating element lead-out electrode 7 connected to the other end of the heating element 4, formed on the insulating layer 6 along the heating element 4 and holding the molten conductor 3a of the fuse element 3.

[0163] Furthermore, in the protection element 40, each of the heating element 4, the heating element power supply electrode 5, and the heating element lead-out electrode 7 are formed on the back surface 2b of the insulating substrate 2 on the opposite side to the surface 2a on which the fuse element 3 is provided, and a support electrode 41 for supporting the fuse element 3 is formed on the surface 2a of the insulating substrate 2. The heating element lead-out electrode 7 formed on the back surface 2b is connected to the support electrode 41 via a through hole 42 penetrating the insulating substrate 2, whereby the insulating substrate 2 constitutes a fuse member 43 for attracting the molten conductor 3a of the molten fuse element 3 to the heating element lead-out electrode 7 side via the through hole 42 and melting the fuse element 3.

[0164] One end of each heating element 4 is connected to the heating element power supply electrode 5, and the other end is connected to the heating element electrode 8. The heating element electrode 8 is connected to the heating element lead-out electrode 7. When each heating element 4 is energized via the heating element power supply electrode 5, the heating element power supply electrode 5 side becomes a high potential portion, and the heating element electrode 8 and the heating element lead-out electrode 7 side become low potential portions. In addition, each heating element 4 is covered by an insulating layer 6 and overlaps with the heating element lead-out electrode 7 formed on the insulating layer 6.

[0165] The heating element lead-out electrode 7 has a front end portion 7a extending on the high potential portion side of each heating element 4 when power is supplied, and a base portion 7b extending on the low potential portion side, and an overlapping area S1 between the front end portion 7a and the heating element 4 is smaller than an overlapping area S2 between the base portion 7b and the heating element 4. Thus, similarly to the protection element 1, the protection element 20 is unlikely to generate sparks (discharges) even when a high voltage is applied through an external circuit, and can safely and quickly block the current path. In addition, in the protection element 40, similarly to the protection element 30, the heating element lead-out electrode 7 can be of the type of Figures 10 to 13 Various compositions shown.

[0166] The support electrode 41 is connected to the fuse element 3 via a bonding material such as a connection solder 9. When the fuse element 3 melts, the molten conductor 3a is condensed and held. In addition, a through hole 42 is formed in the support electrode 41 to attract the molten conductor 3a of the fuse element 3 by a capillary phenomenon, thereby reducing the volume of the molten conductor 3a held on the support electrode 41. Fig.19 As shown, even when the cross-sectional area of ​​the fuse element 3 is increased to cope with high current applications, thereby increasing the amount of the molten conductor 3a, the protection element 40 can reduce the amount of the molten conductor 3a held by the support electrode 41 by allowing the through hole 42 to attract and be held by the heating element lead-out electrode 7, thereby enabling the fuse element 3 to be effectively blown.

[0167] Similar to the heat generating body lead-out electrode 7 , the support electrode 41 can be formed by a known method such as printing using a known electrode material such as Ag, Cu, or an alloy material mainly composed of Ag or Cu.

[0168] In addition, similarly to the through hole 33, the through hole 42 has a conductive layer 44 formed on its inner surface that is connected to the support electrode 41 and the heating element lead-out electrode 7. The conductive layer 44 has the same structure and function as the conductive layer 34, so detailed description is omitted. In addition, in the protection element 40, a plurality of through holes 42 can be formed to increase the path for attracting the molten conductor 3a of the fuse element 3, thereby attracting more molten conductors 3a, thereby reducing the volume of the molten conductor 3a at the fused portion.

[0169] It should be noted that, on the surface 2a of the insulating substrate 2, an auxiliary electrode 45 is connected together with the support electrode 41, and the auxiliary electrode 45 is connected to the fuse element 3 and holds the molten conductor 3a. In addition, the fuse element 3 is provided separately from the insulating substrate 2, and is connected to the first electrode and the second electrode terminals 46 and 47 connected to the external circuit via a bonding material such as a connecting solder 9. In addition, the heating element power supply electrode 5 is also provided separately from the insulating substrate 2, and is connected to the third electrode terminal 48 connected to the external circuit.

[0170] The insulating substrate 2 having such a structure constitutes the following fuse component 43: the auxiliary electrode 45 and the support electrode 41 are connected to the fuse element 3 via the bonding material. If the heating element 4 is energized to generate heat, the fuse element 3 is melted due to the heat, and its molten conductor 3a is attracted to the heating element lead-out electrode 7 side through the through hole 42 to block it.

[0171] In addition, the protection element 40 may also be Fig. 20 As shown, the fuse element 3 is sandwiched by a plurality of fuse members 43 . Fig. 20 In the protection element 40 shown, the fuse members 43 are respectively arranged on one surface and the other surface of the fuse element 3 . Fig.21 4 is a circuit diagram of the protection element 40. In each of the fuse components 43 disposed on the surface and the back of the fuse element 3, one end of the heating element 4 is connected to the fuse element 3 via the heating element lead-out electrode 7 and the support electrode 41 formed on each insulating substrate 2, and the other end of the heating element 4 is connected to a power source for generating heat for the heating element 4 via the heating element power supply electrode 5 formed on each insulating substrate 2.

[0172] In addition, if Fig. 22 As shown, in the protection element 40, when the fuse element 3 is melted by the heat generated by the heating element 4, the heating elements 4 of the fuse members 43, 43 connected to both sides of the fuse element 3 generate heat, and the fuse element 3 is heated from both sides. Therefore, the protection element 40 can quickly heat and melt the fuse element 3 even when the cross-sectional area of ​​the fuse element 3 is increased to cope with high current applications.

[0173] In addition, in the protection element 40, the molten conductor 3a is attracted from both sides of the fuse element 3 into each through hole 42 of the insulating substrate 2 formed in each fuse member 43. Therefore, even when the cross-sectional area of ​​the fuse element 3 is increased to cope with a large current application and a large number of molten conductors 3a are generated, the protection element 40 can attract the molten conductor 3a by the plurality of fuse members 43 and reliably blow the fuse element 3. In addition, the protection element 40 can blow the fuse element 3 more quickly by attracting the molten conductor 3a by the plurality of fuse members 43.

[0174] In the protection element 40, even when a coating structure in which a low-melting-point metal constituting an inner layer is coated with a high-melting-point metal is used as the fuse element 3, the fuse element 3 can be quickly blown. That is, even when the heating element 4 is heated, the fuse element 3 coated with a high-melting-point metal takes time to be heated to a temperature at which the high-melting-point metal of the outer layer melts. Here, the protection element 40 has a plurality of fuse components 43, and each heating element 4 is heated at the same time, so that the high-melting-point metal of the outer layer can be quickly heated to a melting temperature. Therefore, according to the protection element 40, the thickness of the high-melting-point metal layer constituting the outer layer can be made thicker, and the rapid blowout characteristics can be maintained while achieving further high rating.

[0175] In addition, the protection element 40 is preferably as follows Fig. 20 As shown, a pair of fuse members 43, 43 are connected to the fuse element 3. Thus, the protection element 40 can heat the same part of the fuse element 3 from both sides by using the pair of fuse members 43, 43, and attract the molten conductor 3a, so that the fuse element 3 can be heated and melted more quickly.

[0176] In addition, the protection element 40 is preferably configured such that the auxiliary electrode 45 and the support electrode 41 formed on each insulating substrate 2 of the pair of fuse members 43, 43 face each other via the fuse element 3. Thus, by symmetrically connecting the pair of fuse members 43, 43, the load applied to the fuse element 3 during reflow mounting, etc. does not become unbalanced, and the resistance to deformation can be improved.

[0177] It should be noted that, in either case where the heating element 4 is formed on the surface 2a or the back surface 2b of the insulating substrate 2, it is preferred to form it on both sides of the through hole 42 from the perspective of heating the support electrode 41 and the heating element lead-out electrode 7, and condensing and attracting more molten conductors 3a.

[0178] Second embodiment

[0179] Next, an embodiment of the protection element 30 is described. In the second embodiment, Fig.10 The protection element 30 shown, and Fig.26 and Fig.23 The protection element shown has a rectangular heating element lead-out electrode, and determines whether there is a spark when a voltage of 50V, 100V, and 200V is applied. In addition, the melting time of the fuse element is evaluated, and the case of melting within the predetermined time (60 seconds) is evaluated as ○ (good), and the case of not melting within the predetermined time is evaluated as × (bad).

[0180] The dimensions of the various parts of the protection element according to the examples and comparative examples are defined as follows: The numerical values ​​of the various parts shown in Table 3 are numerical values ​​indicating ratios when E of Example 2 is set to 1.

[0181] D: The distance between the front end of the heating element lead-out electrode and the heating element power supply electrode

[0182] E: Length of the heating element in the direction of current flow

[0183] F: Minimum width of the heating element lead electrode

[0184] G: Maximum width of the heating element lead-out electrode

[0185] L: The width between the side edge of the front end of the heating element lead-out electrode and the side edge of the base

[0186] M: Width between the outer edge of the substrate of the heating element and the side edge (front end) of the heating element lead-out electrode

[0187] N: The distance between the side edge (front end) of the heating element lead-out electrode and the side edge of the heating element in the width direction of the heating element

[0188] P: The length of the heating element lead-out electrode

[0189] Q: The overlapping length between the heating element lead-out electrode and the heating element

[0190] [Table 3]

[0191]

[0192] [Example 2]

[0193] The protection element used in Example 2 is Fig.10 The protection element shown. In the protection element involved in Example 2, a base (width G: 0.71) and a front end (width F: 0.21) are provided on the heating element lead-out electrode, and the base is formed to be 0.25 wider on one side than the front end. In addition, the heating element lead-out electrode does not protrude toward the heating element power supply electrode side compared with the fuse element, and the distance D between the front end of the heating element lead-out electrode and the heating element power supply electrode is 0.04, and the overlapping length Q between the heating element lead-out electrode and the heating element is set to 0.54.

[0194] [Comparative Example 3]

[0195] The protection element used in Comparative Example 3 Fig.26 The protection element shown. In the protection element involved in Comparative Example 3, a rectangular heating element lead-out electrode (width: 0.44) is formed. In addition, the heating element lead-out electrode does not protrude toward the heating element power supply electrode side compared to the fuse element, and the distance D between the front end of the heating element lead-out electrode and the heating element power supply electrode is 0.04, and the overlapping length Q between the heating element lead-out electrode and the heating element is set to 0.96.

[0196] [Comparative Example 4]

[0197] The protection element used in Comparative Example 4 Fig.23 The protection element shown. As in Comparative Example 3, the protection element involved in Comparative Example 4 also uses a rectangular heating element lead-out electrode (width: 0.21). The difference from Comparative Example 3 is that in the protection element involved in Comparative Example 4, the heating element lead-out electrode does not overlap with the heating element (Q=0.00). In addition, in Comparative Example 4, the distance D between the front end of the heating element lead-out electrode and the heating element power supply electrode is 0.04.

[0198] [Table 4]

[0199]

[0200] As shown in Table 4, in Example 2, no sparks were generated when any voltage was applied, and the fuse element was able to be melted within the predetermined time. On the other hand, in Comparative Example 3, sparks were generated when voltages of 100V and 200V were applied, but the fuse element was not able to be melted within the predetermined time. In addition, in Comparative Example 4, no sparks were generated when any voltage was applied, but since a narrow rectangular heating element lead-out electrode with a width of 0.21 was used, the capacity of the molten conductor of the fuse element was insufficient, as shown in FIG. Fig.24 As shown, the molten conductor is connected between the first electrode and the second electrode, and the fuse element cannot be melted within a predetermined time.

[0201] Explanation of symbols

[0202] 1: protection element, 2: insulating substrate, 2a: surface, 2b: back, 3: fuse element, 3a: melting conductor, 4: heating element, 4a: protrusion, 5: heating element power supply electrode, 5a: third external connection electrode, 6: insulating layer, 7: heating element lead-out electrode, 7a: front end, 7b: base, 8: heating element electrode, 9: connecting solder, 11: first electrode, 11a: first external connection electrode, 12: second electrode, 12a: second external connection electrode, 13: low melting point metal layer, 14: high melting point metal layer, 17: limiting wall, 20: battery pack, 2 0a: positive terminal, 20b: negative terminal, 21a~21d: battery cell, 22: charging device, 23: current control element, 24: control unit, 25: battery stack, 26: charge and discharge control circuit, 27: detection circuit, 28: current control element, 30: protection element, 32: holding electrode, 33: through hole, 34: conductive layer, 40: protection element, 41: supporting electrode, 42: through hole, 43: fuse component, 44: conductive layer, 45: auxiliary electrode, 46: first electrode terminal, 47: second electrode terminal, 48: third electrode terminal.

Claims

1. A protection element, characterized in that: have: Insulating substrate, a fuse element provided on one side of the insulating substrate, a heating element formed on the insulating substrate and capable of melting the fuse element by generating heat, a heating element power supply electrode connected to one end of the heating element and serving as a power supply terminal for supplying power to the heating element, an insulating layer covering the heating element, and a heating element lead-out electrode connected to the other end of the heating element, formed on the insulating layer along the heating element and holding the molten conductor of the fuse element, When the heating element is energized via the heating element power supply electrode, the heating element power supply electrode side becomes a high potential portion, and the heating element extraction electrode side becomes a low potential portion. In the heating element lead-out electrode, the overlapping area between the front end portion extending on the high potential portion side of the heating element and the heating element is smaller than the overlapping area between the base portion extending on the low potential portion side of the heating element and the heating element. The fuse element is mounted on the heating element lead-out electrode. The front end portion of the heat generating body lead-out electrode does not protrude toward the heat generating body power supply electrode side relative to the side edge of the fuse element.

2. The protection element according to claim 1, wherein when a direction perpendicular to a current-carrying direction of the heating element is defined as a width direction, In the heat generating body lead-out electrode, the width of the front end portion is narrower than the width of the base portion. 3 . The protection element according to claim 2 , wherein in a hypothetical region in which the front end portion is assumed to have the same width as the base portion, an overlapping area with the heat generating element is narrower than a non-overlapping area with the heat generating element in the hypothetical region. 4 . The protection element according to claim 1 , wherein in the heat generating body lead-out electrode, an area of ​​the front end portion is smaller than an area of ​​the base portion. 5 . The protection element according to claim 1 , wherein in the heat generating element lead-out electrode, the entire front end portion overlaps with the heat generating element. 6 . The protection element according to claim 4 , wherein in the heat generating element lead-out electrode, the entire front end portion overlaps with the heat generating element. 7 . The protection element according to claim 1 , wherein the heating element comprises two heating elements, and the two heating elements are separated from each other and arranged in parallel on the insulating substrate.

8. The protection element according to claim 7, wherein the front end portion of the heating element lead-out electrode is formed in a region between the two heating elements. The front end portion does not overlap with the two heating elements. 9 . The protection element according to claim 7 , wherein the front end portion of the heat generating element lead-out electrode is formed in a region between the two heat generating elements, and a portion of the front end portion overlaps with at least one of the heat generating elements.

10. The protection element according to any one of claims 7 to 9, wherein a holding electrode for holding a molten conductor of the fuse element is formed on the other surface opposite to the one surface of the insulating substrate, The heating element lead-out electrode and the holding electrode are connected via a through hole penetrating the insulating substrate. The insulating substrate attracts the melted molten conductor of the fuse element to the holding electrode side via the through hole. 11 . The protection element according to claim 1 , wherein a voltage applied to the heating element power supply electrode is 100 V or more.

12. A battery pack comprising: More than one battery cell, a protection element connected to the charge and discharge path of the battery cell and blocking the charge and discharge path, and a current control element for detecting a voltage value of the battery cell and controlling current flow to the protection element; The protection element has: Insulating substrate, a fuse element provided on one side of the insulating substrate, a heating element formed on the insulating substrate and capable of melting the fuse element by generating heat, a heating element power supply electrode connected to one end of the heating element and serving as a power supply terminal for supplying power to the heating element, an insulating layer covering the heating element, and A heating element lead-out electrode connected to the other end of the heating element, formed on the insulating layer along the heating element and holding the molten conductor of the fuse element; When the heating element is energized via the heating element power supply electrode, the heating element power supply electrode side becomes a high potential portion, and the heating element extraction electrode side becomes a low potential portion. In the heating element lead-out electrode, the overlapping area between the front end portion extending on the high potential portion side of the heating element and the heating element is smaller than the overlapping area between the base portion extending on the low potential portion side of the heating element and the heating element. The fuse element is mounted on the heating element lead-out electrode. The front end portion of the heat generating body lead-out electrode does not protrude toward the heat generating body power supply electrode side relative to the side edge of the fuse element.

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