Protective element and battery pack

Abstract

The invention provides a protective element which can eliminate redundant parts of an adhesive between a fitting convex part and a fitting concave part and reliably ensure the bonding strength of a lower side shell and an upper side shell. The protective element is provided with: a fusible conductor (3); and a housing (6) having a lower housing (4) and an upper housing (5) and formed by joining the upper housing (5) and the lower housing (4) by means of an adhesive, one of the upper housing (5) and the lower housing (4) being provided with a fitting recess (25), the other being provided with a fitting projection (26) that fits into the fitting recess (25), and a slit (27). And a slit (27) that is continuous with the fitting recess (25), extends to the abutting surface of the upper housing (5) and the lower housing (4), and causes the adhesive (19) to flow therethrough.

Description

[0001] This application is a divisional application of the following application:

[0002] Invention name: Protection element, battery pack International application date: August 18, 2020 International application number: PCT / JP2020 / 031182

[0003] National application number: 202080057909.4 Technical Field

[0004] The present technology relates to a protection element that blocks a current path, and a battery pack using the protection element. This application claims priority based on Japanese patent application No. 2019-157431 filed in Japan on August 29, 2019, which is incorporated herein by reference. Background Art

[0005] Many rechargeable and reusable secondary batteries are processed into battery packs and provided to users. In particular, in order to ensure the safety of users and electronic devices, lithium-ion secondary batteries with high weight energy density generally have built-in protection circuits such as overcharge protection and over-discharge protection in the battery pack, which have the function of blocking the output of the battery pack under specified circumstances.

[0006] In many electronic devices using lithium-ion secondary batteries, the output is turned on / off using a FET switch built into the battery pack, thereby performing overcharge protection or over-discharge protection for the battery pack. However, in the case where the FET switch is short-circuited and damaged for some reason, in the case where a large current flows instantaneously due to a lightning surge, or in the case where the output voltage drops abnormally due to the life of the battery cell or conversely an excessive abnormal voltage is output, the battery pack and electronic equipment must be protected from accidents such as fire. Therefore, in order to safely block the output of the battery cell in any abnormal state that may be conceivable, a protection element composed of a fuse element having the function of blocking the current path according to a signal from the outside is used.

[0007] As such a protection element for a protection circuit of a lithium ion secondary battery or the like, a structure is used in which a heating element is provided inside the protection element and a fusible conductor on a current path is melted by heat generated by the heating element.

[0008] Prior art literature

[0009] Patent Literature

[0010] Patent Document 1: Japanese Patent Application Publication No. 2015-53260 Summary of the invention

[0011] Problems to be solved by the invention

[0012] In recent years, the use of lithium-ion secondary batteries has expanded, and research has been conducted on their use in larger current applications, 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 be used. In these applications, especially during startup, a large current of more than several 10A to 100A sometimes flows. It is desirable to realize a protective element capable of handling such a large current capacity.

[0013] In order to realize a protection element that can cope with such a large current, a protection element has been proposed that uses a fusible conductor with a large cross-sectional area and connects an insulating substrate having a heating element formed thereon to the front surface of the fusible conductor.

[0014] Fig.26 , Fig. 27 , Fig.28 , Fig.29 This is a diagram showing a configuration example of a protection element assumed for large current use. Fig.26 It is a three-dimensional picture of the appearance. Fig. 27 It is a top view. Fig.28 yes Fig. 27 The D-D' section view in Fig.29 This is a plan view showing the upper housing without the upper housing. Figure 26 to Figure 29 The protection element 100 shown constitutes a part of the external circuit by connecting a fusible conductor 103 between the first and second external connection terminals 101 and 102 connected to the external circuit such as the battery charging and discharging circuit. In the event of an abnormality such as an overvoltage, the fusible conductor 103 melts and the current path between the first external connection terminal 101 and the second external connection terminal 102 is blocked.

[0015] The protection element 100 comprises: an insulating substrate 105, a first and a second external connection terminal 101, 102 connected to an external circuit, two heating elements 106 arranged side by side on the front surface of the insulating substrate 105, an insulating layer 107 covering the heating elements 106, a front electrode 108 stacked on the insulating layer 107 and connected to the heating elements 106, and a fusible conductor 103 mounted by means of solder paste in a manner spanning the first external connection terminal 101, the front electrode 108 and the second external connection terminal 102.

[0016] The first and second external connection terminals 101 and 102 of the protection element 100 are arranged in a manner spanning the inside and outside of the element housing, and are connected to connection electrodes provided on an external circuit substrate on which the protection element 100 is mounted by screw fixing, etc., thereby soluble conductor 103 is assembled to a part of the current path formed on the external circuit substrate.

[0017] The heating element 106 is a conductive component with a high resistance value that generates heat when powered on, and is composed of, for example, nickel-chromium alloy, W, Mo, Ru, etc. or materials containing them. In addition, the heating element 106 is connected to a heating element power supply electrode 109 formed on the front surface of the insulating substrate 105. The heating element power supply electrode 109 is connected to the third external connection terminal 110 by means of solder paste. The third external connection terminal 110 of the protection element 100 is connected to a connection electrode provided on an external circuit substrate for mounting the protection element 100, thereby connecting the heating element 106 to an external power supply provided in an external circuit. Moreover, the heating element 106 is always controlled to be powered on and heated by a switching element, etc., not shown in the figure.

[0018] The heating element 106 is covered with an insulating layer 107 made of a glass layer or the like, and a front electrode 108 is formed on the insulating layer 107, thereby overlapping the front electrode 108 via the insulating layer 107. In addition, a fusible conductor 103 is connected to the front electrode 108 by solder paste so as to span between the first and second external connection terminals 101 and 102.

[0019] Thus, the heating element 106 of the protection element 100 and the soluble conductor 103 are thermally connected by overlapping each other, and when the heating element 106 generates heat by energizing, the soluble conductor 103 can be melted.

[0020] The soluble conductor 103 is formed of a low melting point metal such as a Pb-free solder, a high melting point metal such as an alloy mainly composed of Ag, Cu, or these metals, or has a laminated structure of a low melting point metal and a high melting point metal. Moreover, the soluble conductor 103 is connected from the first external connection terminal 101 across the front electrode 108 to the second external connection terminal 102, thereby forming a part of the current path of the external circuit in which the protection element 100 is assembled. Moreover, the soluble conductor 103 is melted due to self-heating (Joule heat) or melted due to the heat of the heating element 106 by passing a current exceeding the rated value, thereby blocking the first and second external connection terminals 101 and 102.

[0021] Furthermore, when the protection element 100 needs to block the current path of the external circuit, the heating element 106 is energized through the switching element. As a result, the heating element 106 of the protection element 100 is heated to a high temperature, and the soluble conductor 103 assembled on the current path of the external circuit is melted. The molten conductor of the soluble conductor 103 is pulled toward the front electrode 108 with high wettability and the first and second external connection terminals 101 and 102, thereby the soluble conductor 103 is melted. Therefore, the protection element 100 can melt between the first external connection terminal 101, the front electrode 108 and the second external connection terminal 102, and block the current path of the external circuit.

[0022] like Fig.30As shown, the protection element 100 has a lower shell 111 and an upper shell 112, and the lower shell 111 and the upper shell 112 are joined to form a housing 113 of the protection element 100. It should be noted that Fig.30 1 is a diagram showing a housing 113, (A) is a bottom view of an upper housing 112, (B) is a cross-sectional view of a lower housing 111 and the upper housing 112, and (C) is a top view of the lower housing 111. The lower housing 111 supports an insulating substrate 105 and first and second external connection terminals 101 and 102. The upper housing 112 has a space for accommodating the internal structure of the above-mentioned components.

[0023] The lower shell 111 is formed with a mating protrusion 114 at each corner. In addition, the upper shell 112 is formed with a mating recess 115 at each corner to be mated with the mating protrusion 114. When forming the housing 113, as shown in FIG. Fig.31 As shown, adhesive 120 is supplied to the side edge of the lower housing 111 including the fitting protrusion 114, and the lower housing 111 is butted against the upper housing 112. Thus, the fitting protrusion 114 and the fitting recess 115 are fitted with the adhesive 120, and the lower housing 111 and the upper housing 112 are joined.

[0024] Here, the protective element 100 seeks to increase the size of the fusible conductor 103 and the amount of heat generated by the heating element 106 as described above in order to cope with high current applications. However, along with this, the thermal shock when the fusible conductor 103 melts also increases, and the air inside the shell expands rapidly, so the shell 113 is required to have a bonding strength that can withstand this pressure. In order to improve the bonding strength between the lower shell 111 and the upper shell 112, it is considered to increase the amount of adhesive 120, but if the amount of adhesive 120 is increased, the amount that flows into the mating recess 115 during mating increases. In addition, the adhesive also flows along the mating protrusion 114 and enters between the mating protrusion 114 and the mating recess 115.

[0025] Therefore, if Fig.32 As shown, when the lower housing 111 and the upper housing 112 are butted against each other, there is no space for the adhesive 120 to flow between the fitting protrusion 114 and the fitting recess 115, which hinders the close fitting of the lower housing 111 and the upper housing 112. As a result, the upper housing 112 floats from the lower housing 111, and there is a possibility that the desired bonding strength cannot be obtained, the upper housing 112 falls off when the fusible conductor 103 melts, or the predetermined housing height condition cannot be met.

[0026] Therefore, an object of the present technology is to provide a protection element and a battery pack using the same, which can eliminate the excess portion of the adhesive between the fitting protrusion and the fitting recess and reliably ensure the bonding strength between the lower case and the upper case.

[0027] Solutions for solving problems

[0028] In order to solve the above-mentioned problems, the protection element of the present technology comprises: a fusible conductor; and a shell, which has a lower shell and an upper shell, and is formed by joining the upper shell and the lower shell with an adhesive, and a fitting recess is formed on either side of the upper shell and the lower shell, and a fitting protrusion that fits with the fitting recess is formed on either side, and a slit is formed, which is continuous with the fitting recess and extends to the mating surface of the upper shell and the lower shell, so that the adhesive flows.

[0029] In order to solve the above-mentioned problems, the protection element of the present technology comprises: a fusible conductor; and a shell, which has a lower shell and an upper shell, and is formed by joining the upper shell and the lower shell with an adhesive, and a fitting recess is formed on either side of the upper shell and the lower shell, and a fitting protrusion that fits with the fitting recess is formed on either side, and the fitting protrusion has a slit formed on the outer peripheral surface to allow the adhesive to flow.

[0030] In order to solve the above-mentioned problems, the protection element of the present technology comprises: a fusible conductor; and a shell, which has a lower shell and an upper shell, and is formed by joining the upper shell and the lower shell with an adhesive, and a fitting recess is formed on either side of the upper shell and the lower shell, and a fitting protrusion that fits with the fitting recess is formed on either side, and a slit is formed, which is continuous with the fitting recess and extends to the mating surface of the upper shell and the lower shell so that the adhesive flows, and the fitting protrusion has a slit formed on the outer peripheral surface so that the adhesive flows.

[0031] In addition, the battery pack of the present technology comprises: one or more battery cells; and a protection element, which is connected to the charge and discharge path of the above-mentioned battery cells and blocks the charge and discharge path, and the above-mentioned protection element comprises: a fusible conductor; and a shell, which has a lower shell and an upper shell, and is formed by joining the above-mentioned upper shell and the above-mentioned lower shell with an adhesive, and an interlocking recess is formed on either side of the above-mentioned upper shell and the above-mentioned lower shell, and an interlocking protrusion that interlocks with the above-mentioned interlocking recess is formed on either side, and a slit is formed, and the slit is continuous with the above-mentioned interlocking recess and extends to the mating surface of the above-mentioned upper shell and the above-mentioned lower shell, so that the above-mentioned adhesive flows.

[0032] In addition, the battery pack of the present technology comprises: one or more battery cells; and a protection element connected to the charge and discharge path of the above-mentioned battery cells to block the charge and discharge path, the above-mentioned protection element comprises: a fusible conductor; and a shell, having a lower shell and an upper shell, formed by joining the above-mentioned upper shell and the above-mentioned lower shell with an adhesive, a fitting recess is formed on either side of the above-mentioned upper shell and the above-mentioned lower shell, and a fitting protrusion that fits with the above-mentioned fitting recess is formed on either side, and the above-mentioned fitting protrusion has a slit formed along the protruding direction for allowing the above-mentioned adhesive to flow.

[0033] In addition, the battery pack of the present technology comprises: one or more battery cells; and a protection element, which is connected to the charge and discharge path of the above-mentioned battery cells and blocks the charge and discharge path, and the above-mentioned protection element comprises: a fusible conductor; and a shell, which has a lower shell and an upper shell, and is formed by joining the above-mentioned upper shell and the above-mentioned lower shell with an adhesive, and a fitting recess is formed on either side of the above-mentioned upper shell and the above-mentioned lower shell, and a fitting protrusion that fits with the above-mentioned fitting recess is formed on either side, and a slit is formed, the slit is continuous with the above-mentioned fitting recess and extends to the mating surface of the above-mentioned upper shell and the above-mentioned lower shell, so that the above-mentioned adhesive flows, and the above-mentioned fitting protrusion has a slit formed along the protruding direction for allowing the above-mentioned adhesive to flow.

[0034] Effects of the Invention

[0035] According to the present technology, when the upper shell and the lower shell are connected, the slit allows the excess adhesive filled in the fitting recess to flow inward, thereby preventing the excess adhesive from being retained in the fitting recess that is fitted with the fitting protrusion. Thus, it is possible to prevent the excess adhesive retained in the fitting recess from hindering the close fitting of the upper shell and the lower shell. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Figure 1 This is a three-dimensional diagram of the appearance of a protection element using this technology.

[0037] Figure 2 It is a cross-sectional view of a protection element to which this technology is applied.

[0038] Figure 3 This is a plan view showing a protection element to which the present technology is applied, with the upper housing omitted.

[0039] Figure 4 This is a cross-sectional view showing a state in which a fusible conductor is melted in a protection element to which the present technology is applied.

[0040] Figure 5 1 and 2 are diagrams showing a lower housing, wherein (A) is a plan view and (B) is a cross-sectional view taken along line EE' of (A).

[0041] Figure 6 1 and 2 are diagrams showing an upper housing, wherein (A) is a bottom view and (B) is a cross-sectional view taken along the line CC' of (A).

[0042] Figure 7 The figures show the bonding process of the lower shell and the upper shell, (A) is a top view of the lower shell showing the flow of the adhesive, and (B) is a cross-sectional view taken along line GG' of (A) showing the flow of the adhesive when the lower shell coated with the adhesive is fitted with the upper shell.

[0043] Figure 8 1 and 2 are diagrams showing modified examples of the recessed slits, wherein (A) is a bottom view of the upper housing, and (B) is a cross-sectional view taken along the line HH' of (A).

[0044] Fig. 9 It is a top view showing a modified example of the recessed slit.

[0045] Fig.10 It is a top view showing a modified example of the recessed slit.

[0046] Fig.11 The figures show the process of joining the lower shell and the upper shell, (A) is a plan view showing the lower shell coated with adhesive, and (B) is a cross-sectional view taken along the line FF' of (A) in which the upper shell and the lower shell are arranged to face each other.

[0047] Fig.12 The figures show a housing in which a convex slit is provided on a lower shell, (A) is a bottom view of an upper shell, (B) is a cross-sectional view in which the upper shell and the lower shell are arranged opposite to each other, and (C) is a top view of the lower shell.

[0048] Fig.13 1 and 2 are diagrams showing a fitting convex portion in which a convex slit is formed, wherein (A) is a plan view and (B) is a JJ' cross-sectional view of (A).

[0049] Fig.14 The figures show a housing in which a convex slit is provided on a lower shell, (A) is a bottom view of an upper shell, (B) is a cross-sectional view in which the upper shell and the lower shell are arranged opposite to each other, and (C) is a top view of the lower shell.

[0050] Fig.15 1 and 2 are diagrams showing a fitting convex portion in which a convex slit is formed, wherein (A) is a plan view and (B) is a JJ' cross-sectional view of (A).

[0051] Fig.16 The figures show an upper housing provided with a fitting protrusion, (A) is a bottom view, and (B) is a cross-sectional view taken along line LL' of (A).

[0052] Fig.171 and 2 are diagrams showing a lower housing provided with a fitting recess, wherein (A) is a plan view and (B) is a cross-sectional view taken along line MM' of (A).

[0053] Fig.18 The figures show the process of joining the lower shell and the upper shell, (A) is a top view of the lower shell showing the flow of the adhesive, and (B) is a cross-sectional view taken along KK' of (A) showing the flow of the adhesive when the lower shell coated with the adhesive is fitted with the upper shell.

[0054] Fig.19 The figures show the process of joining the lower shell and the upper shell, (A) is a plan view showing the lower shell coated with adhesive, and (B) is a NN' cross-sectional view of (A) with the upper shell and the lower shell arranged to face each other.

[0055] Fig. 20 This is a three-dimensional diagram of the appearance of a fusible conductor.

[0056] Fig.21 This is a circuit diagram showing a configuration example of a battery pack.

[0057] Fig. 22 This is a circuit diagram of a protection element to which this technology is applied.

[0058] Fig.23 It is a cross-sectional view showing a modified example of the protection element to which the present technology is applied.

[0059] Fig.24 is a circuit diagram of a protection element according to a modified example.

[0060] Fig.25 It is a cross-sectional view showing a state in which the fusible conductor is melted in the protection element according to the modification.

[0061] Fig.26 This is a perspective view showing the appearance of a protection element that can handle large currents.

[0062] Fig. 27 yes Fig.26 A top view of the protection element is shown.

[0063] Fig.28 yes Fig. 27 D-D' section view in.

[0064] Fig.29 The upper housing is omitted. Fig.26 A top view of the protection element is shown.

[0065] Fig.30 Yes means Fig.26The figures of the housing of the protection element shown in the figure, (A) is a bottom view of the upper housing, (B) is a cross-sectional view showing the lower housing and the upper housing in a state of being arranged opposite to each other, and (C) is a top view of the lower housing.

[0066] Fig.31 The figures show the bonding process of the lower shell and the upper shell, (A) is a cross-sectional view showing the lower shell and the upper shell coated with adhesive in an opposing configuration, and (B) is a top view of the lower shell coated with adhesive.

[0067] Fig.32 1 and 10 are views showing a state where a lower housing and an upper housing are joined, (A) is a bottom view showing an upper housing with an adhesive filled in a fitting recess, and (B) is a cross-sectional view showing a state where the lower housing and the upper housing are joined. DETAILED DESCRIPTION

[0068] Hereinafter, the protection element and battery pack to which the present technology is applied are described in detail with reference to the accompanying drawings. It should be noted that the present technology is not limited to the following embodiments, and various changes can be made without departing from the main purpose of the present technology. In addition, the accompanying drawings are schematic, and sometimes the ratios of various dimensions are different from the actual situation. The specific dimensions should be judged with reference to the following description. In addition, of course, the drawings also include parts with different dimensional relationships and ratios.

[0069] [First embodiment: fitting recessed slit]

[0070] Figure 1 , Figure 2 , Figure 3 1 shows a protection element 1 to which the present technology is applied. The protection element 1 includes: an insulating substrate 2; a fusible conductor 3 mounted on the front surface of the insulating substrate 2; and a housing 6 including a lower housing 4 supporting the back surface of the insulating substrate 2 and an upper housing 5 covering the front surface of the insulating substrate 2, wherein the insulating substrate 2 is accommodated by bonding the lower housing 4 and the upper housing 5 with an adhesive 19. In addition, the protection element 1 includes first and second external connection terminals 7 and 8. The first and second external connection terminals 7 and 8 are arranged in a manner spanning the inside and outside of the housing 6, and are connected to connection electrodes provided in an external circuit to which the protection element 1 is mounted by screw fixing or the like. The first and second external connection terminals 7 and 8 are supported by the lower housing 4, and one end of each is connected by the fusible conductor 3. Furthermore, the protection element 1 is assembled to the external circuit by means of the first and second external connection terminals 7 and 8, whereby the fusible conductor 3 constitutes a part of the current path of the external circuit, and is melted due to the heat generated by the heating element 10 described later or an overcurrent exceeding the rated value, thereby being able to block the current path.

[0071] [Insulating substrate]

[0072] The insulating substrate 2 is formed of an insulating member such as alumina, glass ceramics, mullite, zirconia, etc. In addition, the insulating substrate 2 may also be made of a material used in a printed circuit board such as a glass epoxy substrate or a phenol substrate. Figure 3 In the insulating substrate 2 shown, both side edges in the extending direction of the soluble conductor 3 connected via the front electrode 11 described later are set as the first side edge portions 2c, and both side edges formed with the heating element electrode 15 and the heating element power supply electrode 16 described later are set as the second side edge portions 2d.

[0073] [Heat generating element]

[0074] The heating element 10 that melts the fusible conductor 3 is a conductive member that has a high resistance value and generates heat when electricity is applied, and is composed of, for example, nickel-chromium alloy, W, Mo, Ru, Cu, Ag, or an alloy containing them as a main component. It can be formed by mixing a powder of these alloys or compositions or compounds with a resin binder to form a paste, forming a pattern of the paste on the front surface 2a of the insulating substrate 2 using a screen printing technique, and firing it.

[0075] The heating element 10 is covered by an insulating layer 9 on the front surface 2a of the insulating substrate 2. A front electrode 11 described later is stacked on the insulating layer 9. The insulating layer 9 is provided to protect and insulate the heating element 10 and to efficiently transfer the heat of the heating element 10 to the front electrode 11 and the fusible conductor 3, and is composed of, for example, a glass layer.

[0076] One end of the heating element 10 is connected to a heating element electrode 15 formed on the front surface 2a of the insulating substrate 2. In addition, the heating element electrode 15 is connected to a front electrode 11 formed on the insulating layer 9. Thus, the heating element 10 is electrically connected to the fusible conductor 3 mounted on the front electrode 11. In addition, the other end of the heating element 10 is connected to a heating element power supply electrode 16. The heating element power supply electrode 16 is formed on the front surface 2a of the insulating substrate 2, and is connected to a third external connection terminal 17 by means of a connection material 20 such as solder paste, and is connected to an external circuit by means of the third external connection terminal 17. Moreover, the protection element 1 is connected to the external circuit, and the heating element 10 is assembled to the power supply path to the heating element 10 formed in the external circuit by means of the third external connection terminal 17.

[0077] In addition, if Figure 3 As shown, the heating element 10 is formed so that the current-carrying direction intersects the current-carrying direction of the soluble conductor 3 , and the heating element electrode 15 and the heating element power supply electrode 16 are formed on the second side edge portion 2 d . This is preferable in terms of efficiently using the area of ​​the insulating substrate 2 .

[0078] In addition, a plurality of heating elements 10 may be formed on the front surface of the insulating substrate 2. Figure 3In the example of the protection element 1 shown, two heating elements 10 are formed. The heating elements 10 are electrically connected in parallel, one end of each heating element 10 is connected to a heating element electrode 15 , and the other end of each heating element 10 is connected to a heating element power supply electrode 16 .

[0079] It should be noted that the protection element 1 may also form a heating element 10 inside the insulating layer 9 stacked on the front surface 2a of the insulating substrate 2. In addition, the protection element 1 may also form a heating element 10 inside the insulating substrate 2. In addition, the protection element 1 may also form a heating element 10 on the back surface 2b of the insulating substrate 2. It should be noted that when the heating element 10 is formed on the back surface 2b of the insulating substrate 2, one end of the heating element 10 is connected to the back electrode formed on the back surface 2b of the insulating substrate 2, and is electrically connected to the fusible conductor 2 mounted on the front surface electrode 11 via a conductive through hole that passes through the back surface electrode and the front surface electrode 11. In addition, the other end of the heating element 10 is connected to the third external connection terminal 17 via the heating element power supply electrode formed on the back surface 2b of the insulating substrate 2.

[0080] [Front electrode]

[0081] A front electrode 11 connected to the heating element 10 and to the soluble conductor 3 via the heating element electrode 15 is formed on the insulating layer 9. The front electrode 11 is connected to the soluble conductor 3 via a bonding material 20 such as solder paste. In addition, as for the front electrode 11, when the soluble conductor 3 melts, the molten conductor 3a aggregates, thereby being able to melt the soluble conductor 3.

[0082] The front electrode 11 may also form a suction hole 12. The suction hole 12 is the following member (refer to Figure 4 ): When the soluble conductor 3 melts, the molten conductor 3a is attracted by the capillary phenomenon, and the volume of the molten conductor 3a held on the front electrode 11 is reduced. Even when the cross-sectional area of ​​the soluble conductor 3 is increased to cope with large current applications and the amount of melting is increased, the protective element 1 can reduce the volume of the molten conductor 3a by attracting the molten conductor 3a to the attraction hole 12. The insulating substrate 2 having such a structure constitutes the fuse member 18, and when the heating element 10 is energized and generates heat, the soluble conductor 3 is melted by the heat, and the molten conductor 3a is attracted to the attraction hole 12 to be blocked.

[0083] Thus, the protection element 1 reduces the volume of the molten conductor 3a maintained on the front electrode 11 and more reliably seeks insulation between the first and second external connection terminals 7 and 8. In addition, it is possible to reduce the scattering of the molten conductor 3a caused by arc discharge generated when the molten conductor 3 is melted, prevent the insulation resistance from being reduced, and prevent the molten conductor 3 from being attached to the peripheral circuit of the mounting position and causing a short-circuit fault.

[0084] The suction hole 12 has a conductive layer 13 formed on the inner surface. By forming the conductive layer 13, the suction hole 12 can easily suck the molten conductor 3a. The conductive layer 13 is formed of, for example, any one of copper, silver, gold, iron, nickel, palladium, lead, and tin, or an alloy with any one of them as a main component, and can be formed on the inner surface of the suction hole 12 by a known method such as electrolytic plating and printing of conductive paste. In addition, the conductive layer 13 can also be formed by inserting a plurality of metal wires or a collection of conductive ribbons into the suction hole 12.

[0085] In addition, the suction hole 12 is preferably formed as a through hole that penetrates the thickness direction of the insulating substrate 2. Thus, the suction hole 12 can attract the molten conductor 3a to the back surface 2b side of the insulating substrate 2, and can attract more molten conductor 3a, so that the volume of the molten conductor 3a at the fused portion can be reduced. It should be noted that the suction hole 12 can also be formed as a non-through hole.

[0086] The conductive layer 13 of the suction hole 12 is continuous with the front electrode 11 formed on the front surface 2a of the insulating substrate 2. The front electrode 11 supports the fusible conductor 3 and the fusible conductor 3a is aggregated, so the fusible conductor 3a can be easily guided into the suction hole 12 by the front electrode 11 and the conductive layer 13 being continuous.

[0087] It should be noted that the conductive layer 13 and the front electrode 11 can easily attract the molten conductor 3a of the fusible conductor 3 into the attraction hole 12 by being heated by the heating element 10, and the molten conductor 3a is easily condensed on the front electrode 11. Therefore, the protection element 1 can promote the action of attracting the molten conductor 3a from the front electrode 11 to the attraction hole 12 via the conductive layer 13, and reliably melt the fusible conductor 3.

[0088] In addition, a back electrode 14 connected to the conductive layer 13 of the suction hole 12 may be formed on the back surface 2b of the insulating substrate 2. Since the back electrode 14 is continuous with the conductive layer 13, when the soluble conductor 3 melts, the molten conductor 3a moving through the suction hole 12 is condensed (see Figure 4 ). As a result, the protection element 1 can attract more molten conductors 3a, thereby reducing the volume of the molten conductors 3a at the melting point.

[0089] It should be noted that the protection element 1 may also form a plurality of attraction holes 12 to increase the path for attracting the molten conductor 3a of the soluble conductor 3, and reduce the volume of the molten conductor 3a at the fused portion by attracting more molten conductor 3a. In this case, the plurality of attraction holes 12 may be formed in a manner that spans the width direction of the soluble conductor 3 where the front electrode 11 and the soluble conductor 3 overlap. In addition, the attraction holes 12 may be formed in a region where the front electrode 11 and the soluble conductor 3 do not overlap, where the molten conductor 3a wets and spreads.

[0090] In addition, when two heating elements 10 are arranged in parallel, and in any case where they are formed on the front side 2a, the back side 2b or the inside of the insulating substrate 2, they are preferably formed on both sides of the attraction hole 12 in order to heat the front electrode 11 and the back electrode 14 and to attract and condense more molten conductors 3a.

[0091] [case]

[0092] Next, the housing 6 of the protection element 1 is described. The housing 6 is formed by bonding the lower housing 4 and the upper housing 5 with an adhesive 19. The housing 6 can be formed using, for example, various engineering plastics, thermoplastics, ceramics, or other insulating members. In addition, the housing 6 has an internal space on the front surface 2a of the insulating substrate 2 that is sufficient for the fusible conductor 3 to expand into a spherical shape when melted and for the fusible conductor 3a to condense on the front surface electrode 11 and the first and second external connection terminals 7 and 8.

[0093] The lower shell 4 and the upper shell 5 are joined using an adhesive 19. The adhesive 19 is supplied between the upper end surface of the side wall of the lower shell 4 constituting the side of the housing 6 and the lower end surface 5a of the side wall of the upper shell 5, and is cured, thereby joining the lower shell 4 and the upper shell 5. There is no particular limitation on the adhesive 19, and for example, a thermosetting adhesive can be cited. In addition, the form of the adhesive 19 can be any form as long as it shows fluidity during the joining process, and although its phase state is not limited, it is preferably a liquid state from the perspective of workability.

[0094] In addition, in the protection element to which the present technology is applied, a fitting recess 25 is formed on one of the lower housing 4 and the upper housing 5, and a fitting protrusion 26 that fits with the fitting recess 25 is formed on the other. Hereinafter, the case where the fitting protrusion 26 is provided on the lower housing 4 and the fitting recess 25 is provided on the upper housing 5 will be described as an example.

[0095] [Lower housing]

[0096] Figure 5 : is a diagram showing the lower housing 4, (A) is a top view, (B) is an EE' cross-sectional view of (A). The lower housing 4 is formed in a substantially square shape, and a total of four engaging protrusions 26 are formed at each corner. The engaging protrusion 26 is formed in a cylindrical shape, but the shape of the engaging protrusion 26 can be any convex shape that engages with the engaging recess 25 described later, for example, it can also be a cone, a prism, a pyramid, etc.

[0097] In addition, the lower shell 4 is provided with a concave portion 23 in the approximate center portion thereof for keeping the center portion of the insulating substrate 2 hollow. The lower shell 4 supports the outer edge of the insulating substrate 2 along the side edge of the concave portion 23. By providing the concave portion 23, the contact area between the lower shell 4 and the insulating substrate 2 is reduced, and the heat of the heating element 10 can be suppressed from being absorbed by the lower shell 4. Therefore, the protection element 1 can efficiently transfer the heat of the heating element 10 to the fusible conductor 3, and can melt it more quickly. In particular, by providing the concave portion 23 in the approximate center portion of the lower shell 4, the area directly below the heating element 10 becomes hollow, and the heat dissipation of the heat of the heating element 10 to the lower shell 4 can be suppressed.

[0098] [Upper housing]

[0099] Figure 6 : is a figure showing the upper housing 5, (A) is a bottom view, (B) is a cross-sectional view taken along the line CC' of (A). The upper housing 5 is formed into a substantially square shape similarly to the lower housing 4, and is provided with a total of four fitting recesses 25 at each corner for fitting with the fitting protrusions 26 provided on the lower housing 4. In addition, the upper housing 5 covers the fusible conductor 3, the first and second external connection terminals 7, 8 formed on the front surface 2a of the insulating substrate 2, and has an internal space in which the fusible conductor 3a after melting can be condensed on the front electrode 11 and the first and second external connection terminals 7, 8.

[0100] In addition, the upper housing 5 is formed with a recessed slit 27 which is continuous with the fitting recess 25 and extends to the lower end surface 5a of the side wall of the upper housing 5 which becomes the butt joint surface between the upper housing 5 and the lower housing 4, so that the adhesive 19 flows. Figure 7 As shown, when the upper housing 5 and the lower housing 4 are butted against each other, the concave slit 27 allows the excess portion of the adhesive 19 filled in the fitting concave portion 25 to flow inward, thereby preventing the excess portion of the adhesive 19 from being retained in the fitting concave portion 25 that is fitted with the fitting convex portion 26. Thus, it is possible to prevent the excess portion of the adhesive 19 retained in the fitting concave portion 25 from hindering the close fit between the upper housing 5 and the lower housing 4. It should be noted that, since the amount of adhesive 19 required for the engagement with the fitting convex portion 26 remains in the fitting concave portion 25, the bonding strength between the fitting concave portion 25 and the fitting convex portion 26 is sufficiently ensured. In addition, by providing the concave slit 27, the bonding area with the adhesive 19 is increased, and the bonding strength can be improved.

[0101] Therefore, the protection element 1 is closely attached without the upper shell 5 floating from the lower shell 4, and the desired bonding strength can be obtained. Thus, the protection element 1 can be prevented from having problems such as the upper shell 5 falling off when the fusible conductor 3 melts or failing to meet the specified housing height condition.

[0102] The recessed slit 27 is preferably formed along the side wall lower end surface 5a of the upper housing 5 to which the adhesive 19 is supplied. In addition, there is no particular restriction on the length of the recessed slit 27. There is no particular restriction on the width of the recessed slit 27, but it is preferably less than the diameter of the fitting recessed portion 25 when viewed from above. In addition, there is no particular restriction on the depth of the recessed slit 27, but it is preferably the same as or shallower than the depth of the fitting recessed portion 25.

[0103] In addition, if Figure 6 As shown in (B), the recessed slit 27 is preferably formed into a tapered shape that gradually becomes shallower from the bottom surface side of the fitting recessed portion 25 to the upper surface side of the fitting recessed portion 25 as it moves away from the fitting recessed portion 25. As a result, the excess portion of the adhesive 19 that flows into the recessed slit 27 can be guided to the lower end surface 5a of the side wall of the upper shell 5, which becomes the butt surface between the upper shell 5 and the lower shell 4, and is provided for the joining of the upper shell 5 and the lower shell 4. In addition, by relatively increasing the amount of adhesive supplied to the corner portion of the housing 6, the bonding strength can be improved.

[0104] In addition, if Figure 8 As shown, the recessed slit 27 may be formed to gradually widen as it moves away from the fitting recessed portion 25. This makes it easier for the excess portion of the adhesive 19 to flow out from the fitting recessed portion 25 further toward the slit tip.

[0105] In addition, if Fig. 9 As shown, a plurality of recessed slits 27 may extend from one engaging recessed portion 25. Thus, more excess adhesive 19 can flow out from the engaging recessed portion 25. It should be noted that the shapes (width, length, depth, inclination, etc.) of the plurality of recessed slits 27 may be the same, or may be different so that the amount of adhesive 19 flowing varies depending on the direction.

[0106] In addition, if Fig. 9 As shown, the recessed slits 27 are preferably formed along two adjacent side walls from one fitting recessed portion 25 formed at each corner portion of the upper housing 5. As a result, more excess adhesive 19 can flow out from the fitting recessed portion 25. In addition, as a result, the excess adhesive 19 can be guided to the lower end surface 5a of the side wall of the upper housing 5, which becomes the mating surface with the lower housing 4, and provided for the joining of the upper housing 5 and the lower housing 4.

[0107] It should be noted that the recessed slits 27 are preferably formed in all the fitting recessed portions 25 , but do not necessarily need to be formed in all the fitting recessed portions 25 .

[0108] In addition, if Fig.10As shown in the figure, the recessed slits 27 extending from the adjacent fitting recessed portions 25 may be formed to be continuous with each other. Thus, the excess portion of the adhesive 19 filled in the fitting recessed portions 25 can be led out to the recessed slits 27, and the excess portion of the adhesive 19 supplied to the butt joint surface of the upper housing 5 and the lower housing 4 can be absorbed into the recessed slits 27, thereby preventing the excess portion of the adhesive 19 from hindering the close fit. In addition, by providing the recessed slits 27, the bonding area with the adhesive 19 is increased, and the bonding strength can be improved.

[0109] It should be noted that the upper housing 5 has a recess formed on the lower end face 5a of the side wall that is butted against the lower housing 4, and the recess is used to arrange the first, second external connection terminals 7, 8 and the third external connection terminal 17 supported by the lower housing 4 in a manner that spans the inside and outside of the housing 6. The recess is formed at a position corresponding to the arrangement position of the first, second external connection terminals 7, 8 and the third external connection terminal 17, and the recess has a shape corresponding to the shape of the first, second external connection terminals 7, 8 and the third external connection terminal 17. Therefore, the lower housing 4 of the housing 6 and the upper housing 5 can be butted against each other without a gap, and the first, second external connection terminals 7, 8 and the third external connection terminal 17 can be led out of the housing.

[0110] When forming the shell 6, Fig.11 As shown, adhesive 19 is supplied to the side edge of the lower housing 4 including the fitting protrusion 26, and the lower housing 4 and the upper housing 5 are butted against each other. Thus, the fitting protrusion 26 and the fitting recess 25 are fitted with each other via adhesive 19, and the lower housing 4 and the upper housing 5 are joined.

[0111] [Modification 1]

[0112] Next, a modified example of the protection element to which the present technology is applied is described. The protection element to which the present technology is applied may also replace the recessed slit 27 that is continuous with the fitting recessed portion 25, or may form a convex slit 28 on the fitting convex portion 26 while forming the recessed slit 27 that is continuous with the fitting recessed portion 25. The convex slit 28 is provided on the peripheral surface of the fitting convex portion 26, and prevents the excess adhesive 19 from hindering the close fit between the lower housing 4 and the upper housing 5 by allowing the excess adhesive 19 to flow.

[0113] The convex slit 28 is formed on the outer peripheral surface of the fitting convex portion 26, for example, Fig.12 , Fig.13 As shown, the projection slit 28 is formed in a linear shape along the projection direction of the fitting projection 26 . Fig.12 The figures show a housing 6 having a convex slit 28 on a lower shell 4 , wherein (A) is a bottom view of an upper shell 5 , (B) is a cross-sectional view in which the upper shell 5 and the lower shell 4 are arranged opposite to each other, and (C) is a top view of the lower shell 4 . Fig.131 and 2 are diagrams showing a fitting convex portion 26 in which a convex portion slit 28 is formed, wherein (A) is a plan view and (B) is a JJ′ cross-sectional view of (A).

[0114] It should be noted that the shape of the convex slit 28 is not limited to a straight line shape, and may also be a wave shape, a rectangular wave shape, a sawtooth shape, etc. In addition, the convex slit 28 may be formed in a direction around the outer peripheral surface in addition to being formed along the protruding direction of the fitting convex portion 26. In addition, the convex slit 28 may also be formed in a spiral shape on the outer peripheral surface of the fitting convex portion 26. In addition, the convex slit 28 may be formed continuously or intermittently.

[0115] The direction in which the convex slit 28 is formed is not particularly limited, but it is preferably formed toward the butt joint surface of the lower shell 4 and the upper shell 5 to which the adhesive 19 is supplied. Fig.12 In the illustrated configuration, the convex slit 28 is preferably formed in a direction along the side wall of the lower housing 4. This allows the excess portion of the adhesive 19 to flow toward the butt joint surface of the lower housing 4 and the upper housing 5 to which the adhesive 19 is supplied, and can be provided for bonding. In addition, when the concave slit 27 continuous with the above-mentioned fitting concave portion 25 is provided, it is preferably formed in the same direction as the concave slit 27.

[0116] In addition, the convex slit 28 is preferably formed by the base of the fitting convex portion 26. The base of the fitting convex portion 26 becomes the butt surface of the lower housing 4 and the upper housing 5, so it is possible to promote close fitting by actively absorbing the excess portion of the adhesive 19. In addition, the convex slit 28 is preferably formed over the top of the fitting convex portion 26. Thereby, the excess portion of the adhesive 19 retained in the fitting recess 25 can be easily introduced into the convex slit 28, and the absorption amount of the adhesive 19 can be increased.

[0117] In addition, a plurality of convex slits 28 may be formed in one engaging convex portion 26. Thus, more excess portions of the adhesive 19 can be absorbed into the convex slits 28. Fig.12 As shown, the convex slit 28 is preferably formed in the direction along the two adjacent side walls of the fitting convex portion 26 formed at the corner portion of the lower housing 4. As a result, the excess portion of the adhesive 19 can flow to the butt joint surface of the lower housing 4 and the upper housing 5 to which the adhesive 19 is supplied, and can be provided for bonding. In addition, in the case where the above-mentioned concave slit 27 continuous with the fitting concave portion 25 is provided, it is preferably formed in the same direction as the concave slit 27.

[0118] In addition, if Fig.14 , Fig.15As shown, the convex slit 28 may be formed in a tapered shape whose width gradually decreases from the peripheral surface to the center of the fitting convex portion 26 in a plan view. This allows the capillary phenomenon to work, allowing the adhesive 19 to flow into the convex slit 28, and the inflow amount can be increased.

[0119] In addition, the convex slit 28 may be formed in a tapered shape that gradually widens from the top to the base of the fitting convex portion 26 in cross-sectional view. This allows the capillary phenomenon to work, allowing the excess portion of the adhesive 19 retained on the mating surface of the lower housing 4 and the upper housing 5 to flow into the convex slit 28, and the inflow amount can be increased.

[0120] It should be noted that in Fig.12 , Fig.14 In the protective element 1 shown, the protrusion slit 28 is provided on the fitting protrusion 26 formed on the lower housing 4 so as to fit with the fitting recess 25 formed on the upper housing 5, but a recess slit 27 continuous with the fitting recess 25 may be formed on the upper housing 5. By forming the protrusion slit 28 continuous with the fitting protrusion 26 and the recess slit 27 continuous with the fitting recess 25, more excess part of the adhesive 19 can be absorbed, and the excess part of the adhesive 19 is prevented from hindering the close fit between the lower housing 4 and the upper housing 5.

[0121] [Modification 2]

[0122] In the above-mentioned embodiment, the configuration in which the upper housing 5 is provided with the fitting recess 25 and the recess slit 27, and the configuration in which the lower housing 4 is provided with the fitting protrusion 26 and the protrusion slit 28 has been described, but the protection element to which the present technology is applied may also be provided as follows. Fig.16 , Fig.17 As shown, the above-mentioned fitting protrusion 26 is formed in the upper housing 51, and the above-mentioned fitting recess 25 and recess slit 27 are formed in the lower housing 52. In the following description, the same reference numerals are attached to the same components as those of the above-mentioned protection element 1, and the details thereof are omitted.

[0123] Fig.18 The step of joining the upper housing 51 and the lower housing 52 to form the protection element 50 is shown. Fig.16 1 and 2 are diagrams showing an upper housing 51 provided with a fitting protrusion 26 , wherein (A) is a bottom view and (B) is a cross-sectional view taken along the line LL′ of (A) . Fig.17 2 is a diagram showing a lower housing 52 provided with a fitting recess 25, (A) is a top view, and (B) is a sectional view taken along the line MM' of (A). Fig.17 As shown, the protection element 50 has the above-mentioned fitting recess 25 and recess slit 27 formed on the lower housing 52 .

[0124] The bonding process of the lower housing 52 and the upper housing 51 is the same as that of the above-mentioned protection element 1. Fig.19 As shown in (A) and (B) of FIG. 5 , the adhesive 19 is supplied along the mating surface of the lower housing 52 and the upper housing 51. At this time, the adhesive 19 is supplied to the fitting recesses 25 and the recess slits 27 formed at each corner of the lower housing 52. Then, as shown in FIG. Fig.18 As shown, when the fitting protrusion 26 formed on the upper housing 51 is inserted into the fitting recess 25 and the lower housing 52 is butted against the upper housing 51, the excess portion of the adhesive 19 filled in the fitting recess 25 flows out to the recess slit 27 to prevent it from being retained in the fitting recess 25. Thus, it is possible to prevent the excess portion of the adhesive 19 retained in the fitting recess 25 from hindering the close fit between the upper housing 51 and the lower housing 52. In addition, by providing the recess slit 27, the bonding area with the adhesive 19 is increased, and the bonding strength can be improved.

[0125] [Variation 3]

[0126] In addition, in the protection element 50, the above-mentioned convex slit 28 may be formed on the fitting convex portion 26 formed on the upper housing 51 instead of the concave slit 27 continuous with the fitting concave portion 25 formed on the lower housing 52, or the concave slit 27 continuous with the fitting concave portion 25 is formed. The configuration of the concave slit 27 and the convex slit 28 is described in detail in the protection element 1, and therefore the details are omitted. It should be noted that, in the protection element 50, the configuration of the concave slit 27 and the convex slit 28 may be modified in various ways, as in the protection element 1.

[0127] [Fusible conductor]

[0128] Next, the fusible conductor 3 is described. The fusible conductor 3 is installed across the first and second external connection terminals 7 and 8, and is melted due to self-heating (Joule heat) caused by the heating element 10 due to energization, or when a current exceeding the rated value is energized, the current path between the first external connection terminal 7 and the second external connection terminal 8 is blocked.

[0129] The fusible conductor 3 can be any conductive material that melts due to the heat generated by the heating element 10 or the overcurrent state caused by the energization. For example, in addition to the Pb-free solder of the SnAgCu system, BiPbSn alloy, BiPb alloy, BiSn alloy, SnPb alloy, PbIn alloy, ZnAl alloy, InSn alloy, PbAgSn alloy, etc. can also be used.

[0130] In addition, the fusible conductor 3 may also be a structure containing a high melting point metal and a low melting point metal. Fig. 20As shown, the soluble conductor 3 is a laminated structure composed of an inner layer and an outer layer, and has a low melting point metal layer 31 as an inner layer, and a high melting point metal layer 32 as an outer layer laminated on the low melting point metal layer 31. The soluble conductor 3 is connected to the first and second external connection terminals 7 and 8 and the front electrode 11 by means of a bonding material 20 such as solder paste.

[0131] The low melting point metal layer 31 is preferably solder or a metal with Sn as the main component, which is generally referred to as a "Pb-free solder". The melting point of the low melting point metal layer 31 does not necessarily have to be higher than the temperature of the reflow furnace, and can melt at about 200°C. The high melting point metal layer 32 is a metal layer stacked on the surface of the low melting point metal layer 31, such as Ag or Cu or a metal with any of them as the main component, and has a high melting point that does not melt even when the first and second external connection terminals 7, 8 and the front electrode 11 are connected to the soluble conductor 3 by reflow.

[0132] Such a soluble conductor 3 can be formed by forming a high melting point metal layer on a low melting point metal foil using a plating technique, or can also be formed using other well-known lamination techniques or film formation techniques. In this case, the soluble conductor 3 can have a structure in which the entire surface of the low melting point metal layer 31 is covered by the high melting point metal layer 32, or can have a structure in which all surfaces except a pair of mutually opposed side surfaces are covered. It should be noted that the soluble conductor 3 can be configured to have the high melting point metal layer 32 as an inner layer and the low melting point metal layer 31 as an outer layer, and can also be formed by various structures such as the following structure: a multilayer structure of three or more layers in which low melting point metal layers and high melting point metal layers are alternately laminated, and an opening is provided in a part of the outer layer to expose a part of the inner layer.

[0133] The soluble conductor 3 is formed by laminating the high melting point metal layer 32 as an outer layer on the low melting point metal layer 31 as an inner layer. Therefore, even when the reflow temperature exceeds the melting temperature of the low melting point metal layer 31, the soluble conductor 3 can maintain its shape and not be melted. Therefore, the protection element 1 can efficiently connect the first and second external connection terminals 7 and 8 and the front electrode 11 to the soluble conductor 3 by reflow. In addition, the protection element 1 can also prevent the change of the melting characteristic such as not melting at a predetermined temperature or melting at a temperature lower than the predetermined temperature due to the resistance value locally increasing or decreasing due to the deformation of the soluble conductor 3 by reflow.

[0134] Furthermore, while a predetermined rated current is flowing, the fusible conductor 3 will not melt even if it is self-heated. Furthermore, if a current higher than the rated value flows, the fusible conductor 3 will melt due to self-heating, thereby blocking the current path between the first and second external connection terminals 7 and 8. Furthermore, the fusible conductor 3 is energized by the heating element 10 to generate heat and melt, thereby blocking the current path between the first and second external connection terminals 7 and 8.

[0135] At this time, the molten low-melting-point metal layer 31 of the soluble conductor 3 corrodes the high-melting-point metal layer 32 (solder corrosion), thereby melting the high-melting-point metal layer 32 at a temperature lower than the melting temperature. Therefore, the soluble conductor 3 can be melted in a short time by the corrosive action of the low-melting-point metal layer 31 on the high-melting-point metal layer 32. In addition, the molten conductor 3a of the soluble conductor 3 is cut off by the physical pulling action of the front electrode 11 and the first and second external connection terminals 7 and 8, so that the current path between the first and second external connection terminals 7 and 8 can be quickly and reliably blocked ( Figure 4 ).

[0136] In addition, the soluble conductor 3 is preferably formed such that the volume of the low melting point metal layer 31 is larger than the volume of the high melting point metal layer 32. The soluble conductor 3 is heated by self-heating caused by overcurrent or heating of the heating element 10, and the low melting point metal melts and corrodes the high melting point metal, thereby being able to melt and fuse quickly. Therefore, by forming the volume of the low melting point metal layer 31 to be larger than the volume of the high melting point metal layer 32, the soluble conductor 3 can promote the corrosion action and quickly block the first and second external connection terminals 7 and 8.

[0137] In addition, since the fusible conductor 3 is formed by laminating the high melting point metal layer 32 on the low melting point metal layer 31 as the inner layer, the melting temperature can be greatly reduced compared with the conventional chip fuse (chip fuse) composed of high melting point metal. Therefore, the fusible conductor 3 can have a larger cross-sectional area and a significantly higher current rating than the chip fuse of the same size. In addition, compared with the conventional chip fuse with the same current rating, it can be miniaturized and thinned, and has excellent rapid melting performance.

[0138] In addition, the fusible conductor 3 can improve the resistance (pulse resistance) to surges (surges) in which abnormally high voltages are applied to the electrical system in which the protection element 1 is assembled. That is, the fusible conductor 3 will not melt even when a current of, for example, 100A flows for several milliseconds. In this regard, since a large current flowing in a very short time flows through the surface layer of the conductor (skin effect), the fusible conductor 3 is provided with a high melting point metal layer 32 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, and melting due to self-heating can be prevented. Therefore, the fusible conductor 3 can greatly improve the resistance to surges compared to conventional fuses made of solder alloys.

[0139] It should be noted that the soluble conductor 3 may be coated with flux (not shown) for the purpose of preventing oxidation and improving wettability during melting.

[0140] [Circuit Configuration Example]

[0141] like Fig.21 As shown, such a protection element 1 is used by being incorporated into a circuit in a lithium ion secondary battery pack 33. The battery pack 33 has a battery stack 35 composed of, for example, four lithium ion secondary battery cells 34a to 34d in total.

[0142] The battery pack 33 includes: a battery stack 35; a charge and discharge control circuit 36 ​​for controlling the charge and discharge of the battery stack 35; a protection element 1 according to the present invention for blocking the charge and discharge path when the battery stack 35 is abnormal; a detection circuit 37 for detecting the voltage of each battery cell 34a to 34d; and a current control element 38, which becomes a switching element for controlling the operation of the protection element 1 according to the detection result of the detection circuit 37.

[0143] The battery stack 35 is formed by connecting in series battery cells 34a to 34d that need to be controlled for protection from overcharge and overdischarge, and is detachably connected to the charging device 29 via the positive terminal 33a and the negative terminal 33b of the battery pack 33, and a charging voltage is applied from the charging device 29. The battery pack 33 charged by the charging device 29 can be operated by connecting the positive terminal 33a and the negative terminal 33b to an electronic device that uses the battery to operate.

[0144] The charge and discharge control circuit 36 ​​includes: two current control elements 39a and 39b connected in series in the current path between the battery stack 35 and the charging device 29; and a control unit 40 that controls the operation of these current control elements 39a and 39b. The current control elements 39a and 39b are composed of, for example, field effect transistors (hereinafter referred to as FETs). By controlling the gate voltage by the control unit 40, the conduction and blocking of the current path of the battery stack 35 in the charging direction and / or the discharging direction are controlled. The control unit 40 receives power from the charging device 29 and operates. According to the detection result of the detection circuit 37, when the battery stack 35 is over-discharged or over-charged, the operation of the current control elements 39a and 39b is controlled in a manner to block the current path.

[0145] The protection element 1 is connected to, for example, a charge and discharge current path between the battery stack 35 and the charge and discharge control circuit 36 ​​, and its operation is controlled by a current control element 38 .

[0146] The detection circuit 37 is connected to each battery cell 34a to 34d, detects the voltage value of each battery cell 34a to 34d, and supplies each voltage value to the control unit 40 of the charge and discharge control circuit 36. In addition, when any battery cell 34a to 34d reaches an overcharge voltage or an overdischarge voltage, the detection circuit 37 outputs a control signal for controlling the current control element 38.

[0147] The current control element 38 is composed of, for example, a FET and is controlled in the following manner: based on the detection signal output from the detection circuit 37, when the voltage value of the battery cells 34a~34d becomes a voltage exceeding the specified over-discharge or over-charge state, the protection element 1 is activated to block the charge and discharge current path of the battery stack 35 regardless of the switching action of the current control elements 39a and 39b.

[0148] The protection element 1 to which the present invention is applied and used in the battery pack 33 having the above-mentioned structure has Fig. 22 The circuit configuration is as shown. That is, the first external connection terminal 7 of the protection element 1 is connected to the battery stack 35 side, and the second external connection terminal 8 is connected to the positive terminal 33a side, whereby the fusible conductor 3 is connected in series to the charge and discharge path of the battery stack 35. In addition, the heating element 10 of the protection element 1 is connected to the current control element 38 by means of the heating element power supply electrode 16 and the third external connection terminal 17, and the heating element 10 is connected to the open end of the battery stack 35. Thus, as far as the heating element 10 is concerned, one end is connected to the fusible conductor 3 and one open end of the battery stack 35 by means of the front electrode 11, and the other end is connected to the current control element 38 and the other open end of the battery stack 35 by means of the third external connection terminal 17. Thus, a power supply path is formed to the heating element 10 whose power supply is controlled by the current control element 38.

[0149] [Operation of protection element]

[0150] If the detection circuit 37 detects an abnormal voltage in any of the battery cells 34a to 34d, a blocking signal is output to the current control element 38. Then, the current control element 38 controls the current to energize the heating element 10. As for the protection element 1, the current flows from the battery stack 35 to the heating element 10, whereby the heating element 10 starts to generate heat. In the protection element 1, due to the heat generated by the heating element 10, the fusible conductor 3 melts, thereby blocking the charge and discharge path of the battery stack 35. In addition, as for the protection element 1, the fusible conductor 3 is formed by containing a high melting point metal and a low melting point metal. The low melting point metal melts before the high melting point metal melts. The fusible conductor 3 can be melted in a short time by utilizing the corrosion effect of the molten low melting point metal on the high melting point metal.

[0151] The protection element 1 is melted by the fusible conductor 3 , and the power supply path to the heating element 10 is also blocked, so that the heating element 10 stops generating heat.

[0152] Note that, in the protection element 1 , when an overcurrent exceeding the rated value is supplied to the battery pack 33 , the soluble conductor 3 is melted by self-heating, and the charge and discharge path of the battery pack 33 can be blocked.

[0153] Here, the lower shell 4 and the upper shell 5 of the housing 6 of the protection element 1 are in close contact with each other, and have a desired bonding strength. Therefore, the protection element 1 can prevent the upper shell 5 from falling off when the fusible conductor 3 is melted. In addition, the protection element 1 can meet the prescribed housing height condition because the lower shell 4 and the upper shell 5 of the housing 6 are in close contact with each other.

[0154] In this way, in the protection element 1, the fusible conductor 3 is melted due to the heat generated by the heating element 10 due to the energization or the self-heating of the fusible conductor 3 due to the overcurrent. At this time, even when the fusible conductor 3 is exposed to a high temperature environment such as the reflow mounting to the first and second external connection terminals 7 and 8 and the front electrode 11, the protection element 1 has a structure in which the low melting point metal is covered with the high melting point metal, so that the deformation of the fusible conductor 3 is suppressed. Therefore, the change of the fusing characteristics caused by the change of the resistance value caused by the deformation of the fusible conductor 3 can be prevented, and the fusible conductor 3 is quickly melted by the predetermined overcurrent and the heat generated by the heating element 10.

[0155] The protection element 1 of the present invention is not limited to being used in a battery pack of a lithium-ion secondary battery, but can be applied to various uses that require blocking a current path using an electrical signal.

[0156] [Variation 4]

[0157] Next, other modified examples of the protection element to which the present technology is applied are described. It should be noted that in the following description, the same reference numerals are sometimes used to indicate the same components as the above-mentioned protection elements 1 and 50, and their details are omitted. Fig.23 As shown, in the protection element 60 of the modified example, a plurality of fuse members 18 may sandwich the soluble conductor 3 . Fig.23 In the protection element 60 shown, the fuse members 18 are respectively arranged on one surface and the other surface of the soluble conductor 3 . Fig.24 1 is a circuit diagram of the protection element 60. With respect to each fuse member 18 disposed on the front and back sides of the fusible conductor 3, one end of the heating element 10 is connected to the fusible conductor 3 via the heating element electrode 15 and the front electrode 11 formed on each insulating substrate 2, and the other end of the heating element 10 is connected to a power source for generating heat from the heating element 10 via the heating element power supply electrode 16 and the third external connection terminal 17 formed on each insulating substrate 2.

[0158] In addition, if Fig.25 As shown, when the protective element 60 melts the fusible conductor 3 by the heat generated by the heating element 10, the heating elements 10 of the fuse members 18, 18 connected to both sides of the fusible conductor 3 generate heat, thereby heating the fusible conductor 3 from both sides. Therefore, the protective element 60 can quickly heat and melt the fusible conductor 3 even when the cross-sectional area of ​​the fusible conductor 3 is increased to cope with high current applications.

[0159] The protection element 60 also includes the housing 6 similar to the protection elements 1 and 50 described above, and the fitting recess 25 and the recess slit 27 or the fitting projection 26 and the projection slit 28 are formed in the lower case 4 or the upper case 5 .

[0160] Furthermore, the protection element 60 attracts the molten conductor 3a from both sides of the molten conductor 3 into each attraction hole 12 of the insulating substrate 2 formed in each fuse member 18. Therefore, even when the cross-sectional area of ​​the molten conductor 3 is increased to cope with a large current application and a large amount of the molten conductor 3a is produced, the protection element 60 can attract the molten conductor 3 by using a plurality of fuse members 18 and reliably melt the molten conductor 3. Furthermore, the protection element 60 can melt the molten conductor 3 more quickly by attracting the molten conductor 3a by using a plurality of fuse members 18.

[0161] As for the protection element 60, even in the case of a coating structure in which a low-melting-point metal constituting an inner layer is coated with a high-melting-point metal as the fusible conductor 3, the fusible conductor 3 can be quickly melted. That is, even when the fusible conductor 3 coated with a high-melting-point metal is heated by the heating element 10, it takes time to heat the high-melting-point metal of the outer layer to a temperature at which the high-melting-point metal melts. Here, the protection element 60 includes a plurality of fuse members 18, and each heating element 10 is heated at the same time, thereby being able to quickly heat the high-melting-point metal of the outer layer to a melting temperature. Therefore, according to the protection element 60, the thickness of the high-melting-point metal layer constituting the outer layer can be thickened, and further high rating can be sought while maintaining the rapid melting characteristic.

[0162] In addition, as for the protection element 60, Fig.23 As shown, it is preferred that a pair of fuse members 18, 18 are connected to the soluble conductor 3 in an opposed manner. Thus, the protection element 60 can heat the same position of the soluble conductor 3 from both sides simultaneously by using the pair of fuse members 18, 18 and attract the molten conductor 3a, and can heat and melt the soluble conductor 3 more quickly.

[0163] In addition, in the protection element 60, the front electrodes 11 of the insulating substrates 2 formed on the pair of fuse members 18, 18 are preferably opposed to each other via the soluble conductor 3. Thus, by symmetrically connecting the pair of fuse members 18, 18, the load applied to the soluble conductor 3 is not unbalanced during reflow mounting, etc., and the resistance to deformation can be improved.

[0164] It should be noted that, regardless of whether the heating element 10 is formed on the front surface 2a or the back surface 2b of the insulating substrate 2, it is preferably formed on both sides of the suction hole 12 in order to heat the front electrode 11 and the back electrode 14 and to condense and attract more molten conductors 3a.

[0165] Description of Reference Numerals

[0166] 1: protection element; 2: insulating substrate; 2a: front; 2b: back; 2c: first side edge; 2d: second side edge; 3: fusible conductor; 3a: fusible conductor; 4: lower shell; 5: upper shell; 6: shell; 7: first external connection terminal; 8: second external connection terminal; 9: insulating layer; 10: heating element; 11: front electrode; 12: suction hole; 13: conductive layer; 14: back electrode; 15: heating element electrode; 16: heating element power supply electrode; 17: third external connection terminal; 18: fuse Component; 20: bonding material; 25: fitting recess; 26: fitting protrusion; 27: protrusion slit; 28: slit; 29: charging device; 31: low melting point metal layer; 32: high melting point metal layer; 33: battery pack; 33a: positive terminal; 33b: negative terminal; 34: battery cell; 35: battery stack; 36: charge and discharge control circuit; 37: detection circuit; 38: current control element; 39: current control element; 40: control unit; 50: protection element; 60: protection element; 100: protection element.

Claims

1. A protection element, comprising: A fusible conductor; and A housing having a lower housing and an upper housing, formed by joining the upper housing and the lower housing using an adhesive, A fitting recess is formed in either the upper housing or the lower housing, and a fitting protrusion that fits into the fitting recess is formed in the other, A slit is formed, which is continuous with the fitting recess and extends to the mating surface of the upper housing and the lower housing to allow the adhesive to flow, The fitting recess and the slit are open only at the mating surface of the upper housing and the lower housing.

2. The protection element according to claim 1, Wherein, The slit is formed in a conical shape that gradually becomes shallower from the bottom surface side to the upper surface side of the fitting recess as it moves away from the fitting recess.

3. The protection element according to claim 1 or 2, Wherein, The slit gradually widens as it moves away from the fitting recess.

4. The protection element according to claim 1 or 2, Wherein, A plurality of the slits extend from one of the fitting recesses.

5. The protection element according to claim 4, Wherein, The fitting recess is formed at a corner of the upper housing or the lower housing, The slits are formed from one of the fitting recesses along two adjacent side walls of the housing respectively.

6. The protection element according to claim 1 or 2, Wherein, The fitting recess is formed at all corners of the upper housing or the lower housing.

7. The protection element according to claim 1 or 2, Wherein, When viewed from above, the width of the slit is not more than the diameter of the fitting recess.

8. The protection element according to claim 1 or 2, Wherein, The slits extending from adjacent fitting recesses are continuous with each other.

9. A protection element, comprising: A fusible conductor; and A housing having a lower housing and an upper housing, formed by joining the upper housing and the lower housing using an adhesive, A fitting recess is formed in either the upper housing or the lower housing, and a fitting protrusion that fits into the fitting recess is formed in the other, The fitting protrusion has a slit on its outer peripheral surface to allow the adhesive to flow, The fitting recess is open only at the mating surface of the upper housing and the lower housing.

10. The protection element according to claim 9, Wherein, A plurality of the slits are formed in one of the fitting protrusions.

11. The protection element according to claim 9 or 10, Wherein, The slit is formed in a direction along the side wall of the housing on the peripheral surface of the fitting protrusion.

12. The protection element according to claim 11, Wherein, The fitting protrusion is formed at a corner of the upper housing or the lower housing, The slits are formed in directions along two adjacent side walls of the housing respectively.

13. The protection element according to claim 9 or 10, Wherein, The slit is formed in a conical shape that gradually becomes narrower from the peripheral surface of the fitting protrusion to the center direction when viewed from above.

14. The protection element according to claim 9 or 10, Wherein, The slit is formed in a conical shape that gradually widens from the top to the base of the fitting convex portion when observed in cross-section.

15. A protection element, comprising: A fusible conductor; and A housing having a lower outer shell and an upper outer shell, formed by joining the upper outer shell and the lower outer shell using an adhesive, A fitting recess is formed in either the upper outer shell or the lower outer shell, and a fitting convex portion that fits into the fitting recess is formed in the other, A slit is formed, which is continuous with the fitting recess and extends to the mating surface of the upper outer shell and the lower outer shell to allow the adhesive to flow, The fitting convex portion has a slit on its outer peripheral surface to allow the adhesive to flow, The fitting recess and the slit are open only at the mating surface of the upper outer shell and the lower outer shell.

16. A battery pack, comprising: One or more battery cells; and A protection element connected to the charge and discharge path of the battery cell to block the charge and discharge path, The protection element comprises: A fusible conductor; and A housing having a lower outer shell and an upper outer shell, formed by joining the upper outer shell and the lower outer shell using an adhesive, A fitting recess is formed in either the upper outer shell or the lower outer shell, and a fitting convex portion that fits into the fitting recess is formed in the other, A slit is formed, which is continuous with the fitting recess and extends to the mating surface of the upper outer shell and the lower outer shell to allow the adhesive to flow, The fitting recess and the slit are open only at the mating surface of the upper outer shell and the lower outer shell.

17. A battery pack, comprising: One or more battery cells; and A protection element connected to the charge and discharge path of the battery cell to block the charge and discharge path, The protection element comprises: A fusible conductor; and A housing having a lower outer shell and an upper outer shell, formed by joining the upper outer shell and the lower outer shell using an adhesive, A fitting recess is formed in either the upper outer shell or the lower outer shell, and a fitting convex portion that fits into the fitting recess is formed in the other, The fitting convex portion has a slit along the protruding direction to allow the adhesive to flow, The fitting recess is open only at the mating surface of the upper outer shell and the lower outer shell.

18. A battery pack, comprising: One or more battery cells; and A protection element connected to the charge and discharge path of the battery cell to block the charge and discharge path, The protection element comprises: A fusible conductor; and A housing having a lower outer shell and an upper outer shell, formed by joining the upper outer shell and the lower outer shell using an adhesive, A fitting recess is formed in either the upper outer shell or the lower outer shell, and a fitting convex portion that fits into the fitting recess is formed in the other, A slit is formed, which is continuous with the fitting recess and extends to the mating surface of the upper outer shell and the lower outer shell to allow the adhesive to flow, The fitting convex portion has a slit along the protruding direction to allow the adhesive to flow, The chimeric recess and the slit are open only at the docking surface of the upper housing and the lower housing.

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