JP2017117774A - Fuse element - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a fuse element for securing a formation region of a heating element to stably fuse a soluble conductor even by down-sizing of the fuse element and capable of securing connection strength with mounting substrate by securing a connection area of the mounting electrode.SOLUTION: A fuse element includes: an insulation substrate 10; a first electrode 11 and a second electrode 12 formed on the surface 10a of the insulation substrate 10; a soluble conductor 13 connected across the first and second electrodes 11 and 12; a heating element 14 which is formed on the rear face 10b of the insulation substrate 10 and generates heat by energization to fuse the soluble conductor 13; and a rear face electrode 15 formed on the rear face 10b of the insulation substrate 10. The heating element 14 and the rear surface electrode 15 are overlapped on each other via an insulation layer 17.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a fuse element that protects a circuit by cutting off a power supply line and a signal line.

  For example, as a fuse element used in a protection circuit for a lithium ion secondary battery, a fusible conductor is connected between a first electrode formed on an insulating substrate, a heating element lead electrode connected to the heating element, and a second electrode. Then, a circuit is formed by energizing a fusible conductor on the current path that is fused by self-heating due to overcurrent or a heating element provided inside the fuse element by an external signal. There is one that melts the fusible conductor at the timing that the side intends.

  FIG. 30 shows an example of the fuse element. 30 to 32 is laminated and insulated on an insulating substrate 85, first and second electrodes 81 and 82 formed on both ends of the surface 85a of the insulating substrate 85, and a back surface 85b of the insulating substrate 85. The heating element 84 covered with the layer 86, the intermediate electrode 88 laminated on the surface 85a of the insulating substrate 85 and electrically connected to the heating element 84, and both ends of the first and second electrodes 81 and 82, respectively. And a fusible conductor 83 having a central portion connected to the intermediate electrode 88.

  The first and second electrodes 81 and 82 are connected to the first and second mounting electrodes 91 and 92 provided on the back surface 85 b of the insulating substrate 85 through the through holes 90. The heating element 84 has one end connected to the heating element extraction electrode 87 provided on the back surface 85 b of the insulating substrate 85 and the other end connected to the heating element electrode 93 provided on the back surface 85 b of the insulating substrate 85. . The heating element extraction electrode 87 is connected to the intermediate electrode 88 through the through hole 94. The fusible conductor 83 is made of a material that is quickly melted by the heat generated by the heating element 84, and is made of, for example, low melting point metal such as solder or Pb-free solder containing Sn as a main component.

  When an abnormality such as overcharge or overdischarge is detected, the fuse element 80 is energized to the heating element 84 from the heating element electrode 93 connected to an external circuit. In the fuse element 80, the fusible conductor 83 is melted when the heating element 84 generates heat, and the molten conductor is collected in the first and second electrodes 81 and 82 and the intermediate electrode 88, whereby the first and second fuse elements 80 are collected. The current path between the electrodes 81 and 82 is interrupted.

Japanese Patent No. 2790433

  Requests for downsizing of devices equipped with lithium ion secondary batteries, and requests for space savings due to the need to install a large number of lithium ion secondary batteries to support high current applications such as power tools and electric vehicles Therefore, the fuse element is required to be further downsized.

  As shown in FIG. 32, in the fuse element 80, a heating element 84, a heating element extraction electrode 87, and first and second mounting electrodes 91 and 92 are formed on the back surface 85b of the insulating substrate 85. However, if miniaturization of the fuse element 80 is advanced, the area where the heating element 84 can be disposed by the first and second mounting electrodes 91 and 92 is narrowed, and the soluble conductor 83 cannot be quickly blown even by energization heat generation. Alternatively, it is assumed that there is a risk that the heat generating body 84 itself burns out before the fusible conductor 83 is melted due to local overheating, and the fusible conductor 83 cannot be melted stably. For example, in the fuse element, assuming that the size of the insulating substrate is reduced to 3 mm × 2 mm, the size of the heating element 84 is as small as 0.8 mm × 0.8 mm. The size is limited, making it difficult to handle high current applications.

  On the other hand, if it is intended to secure the formation region of the heating element 84 to some extent, the heating element extraction electrode 87 and the first and second mounting electrodes 91 and 92 become small, and the intermediate electrode 88 and the intermediate electrode 88 formed on the surface 85a of the insulating substrate 85 There is insufficient space for conducting electrical continuity with the first and second electrodes 81 and 82 through castellations and through holes. Alternatively, since the first and second mounting electrodes 91 and 92 become narrow, there is a problem that a connection area to the mounting substrate becomes insufficient, and sufficient connection strength cannot be secured.

  Therefore, the present invention secures the formation area of the heating element and stably melts the fusible conductor even when the fuse element is downsized, and secures the connection area of the mounting electrode to increase the connection strength with the mounting board. An object is to provide a fuse element that can be secured.

  In order to solve the above-described problems, a fuse element according to the present invention includes an insulating substrate, a first electrode and a second electrode formed on a surface of the insulating substrate, and the first and second electrodes. A heat generating element formed on the back surface of the insulating substrate, which generates heat when energized and melts the soluble conductor, and a back electrode formed on the back surface of the insulating substrate. The body and the back electrode are superimposed via an insulating layer.

  According to the present invention, even when the element is downsized, both the effective area of the heating element and the mounting electrode can be maximized. Therefore, the heat generated by the heating element is also transferred from the electrode superimposed via the insulating layer, so that the fusing of the soluble conductor becomes faster and more stable. In addition, it is possible to sufficiently secure the area of the mounting electrode, improve the connection strength with the circuit board, and prevent an increase in the fuse resistance.

FIG. 1 is a plan view showing a surface side of an insulating substrate of a fuse element to which the present invention is applied. 2A is a bottom view showing the back side of the insulating substrate of the fuse element to which the present invention is applied, and FIG. 2B is a cross-sectional view taken along the line A-A ′ of FIG. FIG. 3 is a circuit diagram showing a configuration example of a battery circuit using a fuse element to which the present invention is applied. FIG. 4 is a circuit diagram of a fuse element to which the present invention is applied. FIG. 5A is a plan view showing the surface side of an insulating substrate of another fuse element to which the present invention is applied, and FIG. 5B is a cross-sectional view taken along line A-A ′ of FIG. FIG. 6 is a view showing a manufacturing process of the fuse element shown in FIG. 5, in which a heating element extraction electrode, a lower layer portion of the first and second mounting electrodes, and a heating element electrode are formed on the back surface of the insulating substrate. It is a bottom view which shows the state which formed the 1st insulating layer on it. FIG. 7 is a diagram showing a manufacturing process of the fuse element shown in FIG. 5, and is a bottom view showing a state in which the heating element is superimposed on the lower layer portion by forming the heating element on the first insulating layer. is there. FIG. 8 is a view showing a manufacturing process of the fuse element shown in FIG. 5, and is a bottom view showing a state in which a second insulating layer is formed on the heating element. FIG. 9 is a view showing a manufacturing process of the fuse element shown in FIG. 5 and is a bottom view showing a state in which the upper layer portions of the first and second mounting electrodes are formed on the second insulating layer. 10A is a plan view showing the surface side of an insulating substrate of another fuse element to which the present invention is applied, and FIG. 10B is a cross-sectional view taken along the line A-A ′ of FIG. FIG. 11 is a view showing a manufacturing process of the fuse element shown in FIG. 10 and is a bottom view showing a state in which a heating element extraction electrode and a heating element electrode are formed on the back surface of the insulating substrate. FIG. 12 is a view showing a manufacturing process of the fuse element shown in FIG. 10 and is a bottom view showing a state in which a heating element is formed on the back surface of the insulating substrate. FIG. 13 is a view showing a manufacturing process of the fuse element shown in FIG. 10 and is a bottom view showing a state in which a second insulating layer is formed on the heating element. FIG. 14 is a view showing a manufacturing process of the fuse element shown in FIG. 10, and is a bottom view showing a state in which the upper layer portions of the first and second mounting electrodes are formed on the second insulating layer. FIG. 15A is a plan view showing the surface side of an insulating substrate of another fuse element to which the present invention is applied, and FIG. 15B is a cross-sectional view taken along line A-A ′ of FIG. FIG. 16 is a diagram showing a manufacturing process of the fuse element shown in FIG. 15, in which a heating element extraction electrode, lower layers of the first and second mounting electrodes, and a heating element electrode are formed on the back surface of the insulating substrate, and the heating element is formed. It is a bottom view which shows the state which formed the 3rd insulating layer on the extraction electrode and the lower layer part. FIG. 17 is a view showing a manufacturing process of the fuse element shown in FIG. 15, and is a bottom view showing a state in which a heating element is formed on the third insulating layer. FIG. 18 is a view showing a manufacturing process of the fuse element shown in FIG. 15, and is a bottom view showing a state in which a fourth insulating layer is formed on the heating element. FIG. 19 is a view showing a manufacturing process of the fuse element shown in FIG. 15, and is a bottom view showing a state in which the upper layer portions of the first and second mounting electrodes are formed on the fourth insulating layer. 20A is a plan view showing the surface side of an insulating substrate of another fuse element to which the present invention is applied, and FIG. 20B is a cross-sectional view taken along the line A-A ′ of FIG. FIG. 21 is a view showing a manufacturing process of the fuse element shown in FIG. 20, and is a bottom view showing a state in which a heating element extraction electrode heating element electrode is formed on the back surface of the insulating substrate. FIG. 22 is a view showing a manufacturing process of the fuse element shown in FIG. 20, and is a bottom view showing a state in which a heating element is formed on the back surface of the insulating substrate. FIG. 23 is a view showing a manufacturing process of the fuse element shown in FIG. 20, and is a bottom view showing a state in which a fourth insulating layer is formed on the heating element. FIG. 24 is a view showing a manufacturing process of the fuse element shown in FIG. 20, and is a bottom view showing a state in which the upper layer portions of the first and second mounting electrodes are formed on the fourth insulating layer. FIG. 25A is a plan view showing the surface side of the insulating substrate of the fuse element according to the modification with the cap omitted, and FIG. 25B is a cross-sectional view taken along the line AA ′ of FIG. . FIG. 26 is a B-B ′ cross-sectional view of FIG. FIG. 27 is a cross-sectional view showing a state of being mounted on an external circuit board. FIG. 28 is a plan view showing the surface side of the insulating substrate of the fuse element according to another modification, with the cap omitted. FIG. 29A is a plan view showing the surface side of the insulating substrate of the fuse element according to the modification with the cap omitted, and FIG. 29B is a cross-sectional view taken along the line BB ′ of FIG. . FIG. 30 is a plan view showing the surface side of the insulating substrate of the fuse element according to the reference example. 31 is a cross-sectional view taken along line A-A ′ of FIG. 30. 32 is a bottom view showing the back side of the insulating substrate of the fuse element shown in FIG.

  Hereinafter, a fuse element to which the present invention is applied will be described in detail with reference to the drawings. It should be noted that the present invention is not limited to the following embodiments, and various modifications can be made without departing from the scope of the present invention. Further, the drawings are schematic, and the ratio of each dimension may be different from the actual one. Specific dimensions should be determined in consideration of the following description. Moreover, it is a matter of course that portions having different dimensional relationships and ratios are included between the drawings.

  A fuse element to which the present invention is applied includes an insulating substrate, a first electrode and a second electrode formed on the surface of the insulating substrate, a fusible conductor connected between the first and second electrodes, A heating element that is formed on the back surface of the insulating substrate and that generates heat when energized and melts the fusible conductor, and a back electrode formed on the back surface of the insulating substrate. The heating element and the back electrode are overlapped via an insulating layer. ing.

  The back surface electrode overlapped with the heating element on the back surface of the insulating substrate is, for example, a heating element extraction electrode that is connected to the heating element and constitutes an energization path to the heating element. The back electrode is a first and second mounting electrode connected to the first and second electrodes and mounted on the circuit board. Alternatively, the back electrode is a heating element extraction electrode and first and second mounting electrodes. In addition, the back electrode may be an electrode for heat dissipation or adhesion to a circuit board that is not intended to be energized.

[First Embodiment]
1 and 2 show a fuse element 1 in which a heating element extraction electrode as a back electrode and a heating element are superimposed. The fuse element 1 shown in FIG. 1 is formed on the insulating substrate 10, the first electrode 11 and the second electrode 12 formed on the front surface 10a of the insulating substrate 10, the front surface 10a of the insulating substrate 10, and the back surface 10b. An intermediate electrode 16 electrically connected to the heating element 14 formed on the inner surface of the heat generating element 14, a fusible conductor 13 having both ends connected to the first and second electrodes 11 and 12, and a central portion connected to the intermediate electrode 16. A heating element extraction electrode 15 stacked on the back surface 10b of the insulating substrate 10 and connected to the intermediate electrode 16 and the heating element 14, and a heating element 14 stacked on the heating element extraction electrode 15 via the insulating layer 17, A first mounting electrode 18 formed on the back surface 10b of the insulating substrate 10 and electrically connected to the first electrode 11 and a second mounting electrode 19 electrically connected to the second electrode 12 are provided. .

  The insulating substrate 10 is formed in a substantially rectangular shape by an insulating member such as alumina, alumina ceramic, glass ceramics, mullite, zirconia. In addition, the insulating substrate 10 may be made of a material used for a printed wiring board such as a glass epoxy board or a phenol board. In addition, the fuse element 1 is reduced in size due to demands associated with downsizing of electric devices to be mounted, and the insulating substrate 10 has a size of, for example, 3 mm × 2 mm and a thickness of 0.3 mm.

[First and second electrodes]
The first and second electrodes 11 and 12 are opened by being spaced apart from each other in the vicinity of opposite side edges on the surface 10a of the insulating substrate 10, and a soluble conductor 13 to be described later is mounted. Thus, they are electrically connected via the soluble conductor 13. Further, the first and second electrodes 11 and 12 generate a large current exceeding the rating through the fuse element 1 and the fusible conductor 13 is melted by self-heating (Joule heat), or the heating element 14 generates heat when energized. The fusible conductor 13 is cut off by fusing.

  As shown in FIG. 2A, the first and second electrodes 11 and 12 are first and second mounting electrodes provided on the back surface 10b through a through hole 20 penetrating the insulating substrate 10, respectively. 18 and 19 are connected. The through holes 20 connecting the first and second electrodes 11 and 12 and the first and second mounting electrodes 18 and 19 constitute a part of the energization path of the fuse element 1 and determine the current rating. Therefore, the conductive layer has a predetermined dimension (for example, 0.3 mmφ) and connects the first electrode 11 and the first mounting electrode 18, and the second electrode 12 and the second mounting electrode 19 inside. Is formed.

  The first and second mounting electrodes 18 and 19 are external connection electrodes that are connected to a circuit board such as a protection circuit on which the fuse element 1 is mounted. The first and second mounting electrodes 18 and 19 The second side edges 10c and 10d are separated from each other. The fuse element 1 is connected to the circuit board on which an external circuit is formed via the first and second mounting electrodes 18 and 19, and the first mounting electrode 18, the through hole 20, the first electrode 11, A path extending from the molten conductor 13, the second electrode 12, the through hole 20, and the second mounting electrode 19 constitutes a part of the energization path of the external circuit.

  The first and second mounting electrodes 18 and 19 are provided with castellations on the first and second side edges 10c and 10d of the insulating substrate 10 in place of the through holes 20 or together with the through holes 20, and the casters The first and second electrodes 11 and 12 may be electrically connected to each other even through the connection. Further, the first and second mounting electrodes 18 and 19 secure a connection strength and a predetermined rating by securing a space for conducting through the through hole 20 and the castellation and expanding a connection area to the circuit board. Therefore, a sufficient area is provided, and the resistance of the fuse resistance of the entire element is reduced (for example, 7 mΩ).

  The first and second electrodes 11 and 12 and the first and second mounting electrodes 18 and 19 can be formed using a general electrode material such as Cu or Ag. For example, an Ag—Pd paste is used. It can be formed by printing and baking at 850 ° C. for 30 minutes. Further, on the surfaces of the first and second electrodes 11 and 12 and the first and second mounting electrodes 18 and 19, a coating such as Ni / Au plating, Ni / Pd plating, Ni / Pd / Au plating, or the like is provided. The coating is preferably performed by a known method such as plating. As a result, the fuse element 1 can prevent the first and second electrodes 11 and 12 and the first and second mounting electrodes 18 and 19 from being oxidized, and can prevent a change in rating due to an increase in conduction resistance. it can. Further, when the fuse element 1 is reflow-mounted, the first and second electrodes 11 and 12 are melted by melting the connecting solder for connecting the fusible conductor 13 or the low melting point metal forming the fusible conductor 13. It is possible to prevent erosion (solder erosion), and the first and second mounting electrodes 18, 18 are obtained by melting the connecting solder for connecting the first and second mounting electrodes to the electrodes of the circuit board. 19 can be prevented from being eroded.

  An intermediate electrode 16 is laminated on the surface 10 a of the insulating substrate 10 between the first and second electrodes 11 and 12. The intermediate electrode 16 is connected to the heating element extraction electrode 15 stacked on the back surface 10 b of the insulating substrate 10 through the through hole 21. In the through hole 21, a conductive layer that connects the heating element extraction electrode 15 and the intermediate electrode 16 is formed inside.

[Soluble conductor]
In the fuse element 1, a soluble conductor 13 is connected across the first electrode 11, the intermediate electrode 16, and the second electrode 12. The fusible conductor 13 is made of a material that is quickly melted by the heat generated by the heating element 14, and for example, a low melting point metal such as solder or Pb-free solder whose main component is Sn can be suitably used. As an example, the soluble conductor 13 can be designed to have Sn: Sb = 95: 5, a liquidus point of 240 ° C., and a size of 1 mm × 2 mm.

  The fusible conductor 13 may be made of a high melting point metal such as In, Pb, Ag, Cu, or an alloy containing any of these as a main component, or the inner layer is a low melting point metal and the outer layer is a high melting point. A laminate made of metal may be used. By including the high melting point metal and the low melting point metal, even when the reflow temperature exceeds the melting point of the low melting point metal when the fuse element 1 is reflow mounted, Outflow to the outside can be suppressed, the shape of the soluble conductor 13 can be maintained, a predetermined rating can be maintained, and fluctuations in the cutoff characteristics can be suppressed. In addition, even when fusing, the low melting point metal melts, and the high melting point metal is eroded (soldered), so that the fusing can be quickly performed at a temperature lower than the melting point of the high melting point metal.

  The fusible conductor 13 is connected to the intermediate electrode 16 and the first and second electrodes 11 and 12. The fusible conductor 13 can be easily connected by reflow soldering. As a connecting material for connecting the soluble conductor 13, solder can be preferably used. For example, a connecting solder paste having Sn / Ag / Cu = 96.5 / 3 / 0.5 and a melting point of 219 ° C. is used. it can.

  Further, the soluble conductor 13 is preferably coated with a flux in order to prevent oxidation and improve wettability.

  On the back surface 10b of the insulating substrate 10, a heating element 14, a heating element extraction electrode 15, first and second mounting electrodes 18 and 19, and a heating element electrode 23 are formed, and the heating element 14 and the heating element extraction are formed. The electrode 15 overlaps with the insulating layer 17.

[Heating element extraction electrode]
The heating element extraction electrode 15 is formed on the back surface 10b of the insulating substrate 10 from the third side edge 10e of the insulating substrate toward the center. The heating element extraction electrode 15 can be formed using a general electrode material such as Cu or Ag. For example, the heating element extraction electrode 15 can be formed by printing an Ag—Pd paste and baking it at 850 ° C. for 30 minutes. . The heating element extraction electrode 15 is connected to one end of the heating element 14 and is connected to the intermediate electrode 16 formed on the surface 10 a of the insulating substrate 10 through the through hole 21.

  The heating element lead-out electrode 15 is provided with a castellation on the third side edge 10e of the insulating substrate 10 in place of the through-hole 21 or together with the through-hole 21, and is electrically connected to the intermediate electrode 16 through the castellation. May be.

[Heating element]
The heating element 14 is a conductive member that generates heat when energized, and is made of, for example, W, Mo, Ru, Cu, Ag, or an alloy containing these as main components. The heating element 14 is formed by mixing a powdery body of these alloys, compositions, or compounds with a resin binder, and forming a paste using a screen printing technique, followed by firing (for example, 850 ° C. for 30 minutes). Or the like. The resistance value of the patterned heating element 14 is, for example, 1Ω. The heating element 14 has one end connected to the heating element extraction electrode 15 and the other end connected to the heating element electrode 23.

  The heating element 14 is connected to an external circuit formed on the circuit board via the heating element electrode 23 by mounting the fuse element 1 on the circuit board. The heating element 14 is connected to the first and second electrodes 11 and 12 by being energized and generating heat through a heating element electrode 23 at a predetermined timing to cut off the energization path of the external circuit. The molten conductor 13 can be blown. Moreover, since the heat generating body 14 also cut | disconnects its energization path | route when the soluble conductor 13 blows, heat_generation | fever stops.

  Here, in the fuse element 1, an insulating layer 17 is disposed so as to cover a part of the heating element extraction electrode 15, and the heating element 14 is superimposed on the heating element extraction electrode 15 via the insulation layer 17. . As the insulating material constituting the insulating layer 17, for example, glass having good heat conduction efficiency can be used. After the heating element extraction electrode 15 is formed, the glass paste is printed and baked (for example, 850 ° C. for 30 minutes). can do. After the insulating layer 17 is formed, the heating element 14 is laminated on the back surface 10b and the insulating layer 17 of the insulating substrate 10, and is superimposed on the heating element extraction electrode 15 via the insulating layer 17, thereby generating the heating element extraction electrode. It is connected to a part not covered with 15 insulating layers 17.

  In the fuse element 1, the heating element 14 and the heating element lead-out electrode 15 are overlapped via the insulating layer 17, so that a large space for forming the heating element 14 can be secured in the miniaturized insulating substrate 10. . Therefore, the fuse element 1 can maximize the effective area of the heating element 14, and can melt the soluble conductor 13 quickly and stably. For example, assuming that the size of the insulating substrate is reduced to 3 mm × 2 mm in the fuse element 1, the size of the heating element 14 can be increased to, for example, 0.8 mm × 1.2 mm. Of course, the present invention can form a heating element of any size on an insulating substrate of any size.

  Note that the heating element 14 is preferably overlapped with a part or all of the through hole 21 formed in the heating element extraction electrode 15. Since the heating element 14 and the through hole 21 overlap, the heat of the heating element 14 is transmitted to the intermediate electrode 16 and the fusible conductor 13 mounted on the intermediate electrode 16 through the through hole 21 and can be quickly made. The molten conductor 13 can be blown.

  Further, the fuse element 1 may further be provided with a protective layer (not shown) for protecting the heating element 14. An insulating member such as glass can be suitably used for the protective layer. As a result, the fuse element 1 can prevent short-circuiting with peripheral devices and the like, and can prevent wear and damage of the heating element 14 and improve handling.

  As shown in FIG. 2B, the fuse element 1 has a cap 24 that protects the inside on the surface 10 a of the insulating substrate 10. Thereby, the fuse element 1 can prevent the molten soluble conductor 13 from being scattered and can prevent a short circuit with a peripheral device or the like. The cap 24 can be formed of a synthetic resin such as nylon or LCP resin (liquid crystal polymer). The cap 24 is formed in a size corresponding to the size of the insulating substrate 10 and has a size of, for example, 2.8 × 1.8 and a thickness of 0.5 mm.

[How to use fuse elements]
As shown in FIG. 3, such a fuse element 1 is used by being incorporated in a circuit in a battery pack 30 of a lithium ion secondary battery, for example. The battery pack 30 includes, for example, a battery stack 35 including battery cells 31 to 34 of a total of four lithium ion secondary batteries.

  The battery pack 30 includes a battery stack 35, a charge / discharge control circuit 40 that controls charging / discharging of the battery stack 35, a fuse element 1 to which the present invention that cuts off charging when the battery stack 35 is abnormal, and each battery cell A detection circuit 36 that detects the voltages 31 to 34 and a current control element 37 that controls the operation of the fuse element 1 according to the detection result of the detection circuit 36 are provided.

  The battery stack 35 is formed by connecting battery cells 31 to 34 that need to be controlled for protection from overcharge and overdischarge states, and is detachable via the positive electrode terminal 30a and the negative electrode terminal 30b of the battery pack 30. Are connected to the charging device 45, and a charging voltage from the charging device 45 is applied thereto. The electronic device can be operated by connecting the positive electrode terminal 30a and the negative electrode terminal 30b of the battery pack 30 charged by the charging device 45 to an electronic device operating with a battery.

  The charge / discharge control circuit 40 includes two current control elements 41 and 42 connected in series to a current path flowing from the battery stack 35 to the charging device 45, and a control unit 43 that controls the operation of these current control elements 41 and 42. Is provided. The current control elements 41 and 42 are configured by, for example, field effect transistors (hereinafter referred to as FETs), and the gate voltage is controlled by the control unit 43, whereby the charging direction and / or the discharging direction of the current path of the battery stack 35. Controls continuity and shut-off. The control unit 43 operates by receiving power supply from the charging device 45, and controls the current so as to cut off the current path when the battery stack 35 is overdischarged or overcharged according to the detection result by the detection circuit 36. The operation of the elements 41 and 42 is controlled.

  The fuse element 1 is connected, for example, on a charge / discharge current path between the battery stack 35 and the charge / discharge control circuit 40, and its operation is controlled by the current control element 37.

  The detection circuit 36 is connected to each of the battery cells 31 to 34, detects the voltage value of each of the battery cells 31 to 34, and supplies each voltage value to the control unit 43 of the charge / discharge control circuit 40. The detection circuit 36 outputs a control signal for controlling the current control element 37 when any one of the battery cells 31 to 34 becomes an overcharge voltage or an overdischarge voltage.

  The current control element 37 is composed of, for example, an FET, and when the voltage value of the battery cells 31 to 34 exceeds a predetermined overdischarge or overcharge state by the detection signal output from the detection circuit 36, the fuse element 1 is operated to control the charge / discharge current path of the battery stack 35 to be cut off regardless of the switching operation of the current control elements 41 and 42.

  In the battery pack 30 having the above configuration, the fuse element 1 to which the present invention is applied has a circuit configuration as shown in FIG. That is, the fuse element 1 is fusible by generating heat by energizing the fusible conductor 13 connected in series via the intermediate electrode 16 and the heating element lead-out electrode 15, the intermediate electrode 16 and the fusible conductor 13. The circuit configuration includes a heating element 14 that melts the conductor 13. In the fuse element 1, for example, the fusible conductor 13 is connected in series on the charge / discharge current path, and the heating element 14 is connected to the current control element 37 via the heating element electrode 23. Of the two electrodes 11, 12 of the fuse element 1, one is connected to one open end of the battery stack 35, and the other is connected to the positive electrode terminal 30 a side of the battery pack 30.

  The fuse element 1 having such a circuit configuration can cut off the current path with certainty by fusing the fusible conductor 13 by the heat generated by the heating element 14.

  The protection element of the present invention is not limited to use in a battery pack of a lithium ion secondary battery, and can of course be applied to various uses that require interruption of a current path by an electric signal.

[Second Embodiment]
Next, another embodiment of the fuse element to which the present invention is applied will be described. In the fuse element to which the present invention is applied, the first and second mounting electrodes, which are back electrodes, and the heating element may be overlapped. In the fuse elements 50 and 55 described below, the same members as those of the above-described fuse element 1 are denoted by the same reference numerals, and the details thereof are omitted. In the fuse element 50 shown in FIGS. 5A and 5B, the heating element 14 and the first and second mounting electrodes 18 and 19 are overlapped via the first and second insulating layers 51 and 52. This is different from the fuse element 1 in that respect.

  The first and second mounting electrodes 18 and 19 in the fuse element 50 are respectively provided in lower layer portions 18a and 19a stacked on the back surface 10b of the insulating substrate 10 and upper layer portions 18b and 19b stacked on the second insulating layer 52. And have. The lower layer portions 18a and 19a are formed on the back surface 10b of the insulating substrate 10 so as to be spaced apart from the first and second side edges 10c and 10d of the insulating substrate 10. The lower layer portions 18a and 19a can be formed using a general electrode material such as Cu or Ag. For example, the lower layer portions 18a and 19a can be formed by printing an Ag—Pd paste and baking at 850 ° C. for 30 minutes. The lower layer portions 18 a and 19 a are connected to the first and second electrodes 11 and 12 through the through holes 20 penetrating the insulating substrate 10, respectively.

  The lower layer portions 18 a and 19 a are covered with the first insulating layer 51 except for a part of the insulating substrate 10 on the first and second side edges 10 c and 10 d side. As the insulating material constituting the first insulating layer 51, for example, glass having good heat conduction efficiency can be used, and it can be formed by printing and baking (for example, 850 ° C. for 30 minutes) a glass paste.

  In the fuse element 50, the lower layer portions 18 a and 19 a of the first and second mounting electrodes 18 and 19 and the heating element 14 are superposed via the first insulating layer 51. The heating element 14 is laminated on the back surface 10 b of the insulating substrate 10 and is connected to the heating element extraction electrode 15 and the heating element electrode 23 formed on the back surface 10 b of the insulating substrate 10. The heating element 14 has a second insulating layer 52 laminated thereon. The second insulating layer 52 has an area equal to or larger than the area of the heating element 14 and covers the entire heating element 14. As the insulating material constituting the second insulating layer 52, for example, glass having good heat conduction efficiency can be used, and it can be formed by printing and baking (for example, 850 ° C. for 30 minutes) a glass paste. In the fuse element 50, the upper layer portions 18 b and 19 b of the first and second mounting electrodes 18 and 19 are superimposed on the heating element 14 via the second insulating layer 52. The heating element 14 is superimposed on the lower layer portions 18a and 19a and the upper layer portions 18b and 19b of the first and second mounting electrodes 18 and 19 through the first and second insulating layers 51 and 52, thereby Insulated from the first and second mounting electrodes 18 and 19.

  The upper layer portions 18 b and 19 b are connected to the lower layer portions 18 a and 19 a exposed from the first insulating layer 51. The upper layer portions 18b and 19b are external connection electrodes connected to a circuit board such as a protection circuit on which the fuse element 50 is mounted. The fuse element 50 is connected to a circuit board on which an external circuit is formed via the upper layer portions 18b and 19b of the first and second mounting electrodes 18 and 19, and the upper layer portion 18b, the lower layer portion 18a, the through hole 20, The path extending from the first electrode 11, the fusible conductor 13, the second electrode 12, the through hole 20, the lower layer part 19a, and the upper layer part 19b constitutes a part of the energization path of the external circuit.

  In such a fuse element 50, the heating element 14 and the upper and lower layer portions 18a, 18b, 19a, 19b of the first and second mounting electrodes 18, 19 are interposed via the first and second insulating layers 51, 52. By overlapping, it is possible to secure a large space for forming the heating element 14 in the downsized insulating substrate 10. Therefore, the fuse element 50 can maximize the effective area of the heating element 14, and can melt the soluble conductor 13 quickly and stably. Further, the fuse element 50 can secure a sufficient area of the upper layer portions 18b and 19b of the first and second mounting electrodes 18 and 19, and the mounting area on the circuit board can be maximized to increase the connection strength and A predetermined rating can be provided.

  In addition, it is preferable that the heat generating body 14 overlaps with part or all of the through holes 20 formed in the lower layer portions 18a and 19a. Since the heating element 14 and the through hole 20 overlap each other, the heat of the heating element 14 can be applied to the first and second electrodes 11 and 12 and the first and second electrodes 11 and 12 through the through hole 20. The fusible conductor 13 is transmitted to the mounted fusible conductor 13 and can be blown out quickly.

  Further, the lower layer portions 18a and 19a of the first and second mounting electrodes 18 and 19 are cast on the first and second side edges 10c and 10d of the insulating substrate 10 in place of the through hole 20 or together with the through hole 20. The first and second electrodes 11 and 12 may be conducted through the castellation.

  In the fuse element 50, the first insulating layer 51 is provided in each of the lower layer portions 18 a and 19 a as shown in FIG. 5B, and the heating element 14 is overlapped between the first insulating layers 51. However, one first insulating layer 51 may be provided between the lower layer portions 18 a and 19 a so that the entire heating element 14 is formed on the first insulating layer 51. By providing the first insulating layer 51 between the back surface 10b of the insulating substrate 10 and the heating element 14, the heat of the heating element can be efficiently transferred to the insulating substrate 10 side.

  Such a fuse element 50 can be manufactured by the steps shown in FIGS. First, as shown in FIG. 6, the heating element extraction electrode 15, the lower layer portions 18 a and 19 a of the first and second mounting electrodes 18 and 19, and the heating element electrode 23 are formed on the back surface 10 b of the insulating substrate 10. Next, the first insulating layer 51 is formed on the lower layer portions 18a and 19a except for a part of the insulating substrate 10 on the first and second side edges 10c and 10d side.

  Next, as shown in FIG. 7, a heating element 14 is formed. The heating element 14 is formed on the first insulating layer 51 so as to overlap the lower layer portions 18a and 19a. The heating element 14 is connected to the heating element extraction electrode 15 and the heating element electrode 23.

  Next, as shown in FIG. 8, the second insulating layer 52 is formed on the heating element 14. The second insulating layer 52 covers the entire heating element 14 and exposes the lower layer portions 18a and 19a except for a part of the insulating substrate 10 on the first and second side edges 10c and 10d side. .

  Then, as shown in FIG. 9, the upper layer portions 18 b and 19 b of the first and second mounting electrodes 18 and 19 are formed on the second insulating layer 52. The upper layer portions 18b and 19b are connected to the lower layer portions 18a and 19a at a part of the insulating substrate 10 on the first and second side edges 10c and 10d side.

[Third Embodiment]
Further, as shown in FIGS. 10A and 10B, the fuse element does not include the lower layer portions 18a and 19a of the first and second mounting electrodes 18 and 19, and the first and second via the castellation 53. The two electrodes 11 and 12 may be connected to the upper layer portions 18b and 19b. The fuse element 55 shown in FIG. 10 is different from the fuse element 50 in that the lower layer portions 18a and 19a of the first and second mounting electrodes 18 and 19 are not provided. In this case, it is not necessary to provide the first insulating layer 51 that insulates the heating element 14 and the lower layer portions 18a and 19a, but an insulating layer is provided between the back surface 10b of the insulating substrate 10 and the heating element 14. Also good.

  Such a fuse element 55 can be manufactured by the steps shown in FIGS. First, as shown in FIG. 11, the heating element extraction electrode 15 and the heating element electrode 23 are formed on the back surface 10 b of the insulating substrate 10. Next, as shown in FIG. 12, a heating element 14 is formed. The heating element 14 is connected to the heating element extraction electrode 15 and the heating element electrode 23.

  Next, as shown in FIG. 13, a second insulating layer 52 is formed on the heating element 14. The second insulating layer 52 covers the entire heating element 14. Then, as shown in FIG. 14, the upper layer portions 18 b and 19 b of the first and second mounting electrodes 18 and 19 are formed on the second insulating layer 52. The upper layer portions 18b and 19b are formed by first and second electrodes formed on the surface 10a of the insulating substrate 10 through castellations 53 formed on the first and second side edges 10c and 10d of the insulating substrate 10, respectively. 11 and 12 are connected.

[Fourth Embodiment]
In the fuse element to which the present invention is applied, the heating element extraction electrode as the back electrode and the first and second mounting electrodes may be overlapped with the heating element. In the fuse element 60 described below, the same members as those of the fuse element 1 and the fuse element 50 described above are denoted by the same reference numerals, and the details thereof are omitted. In the fuse element 60 shown in FIGS. 15A and 15B, the heating element 14 and the heating element lead-out electrode 15 are overlapped via a third insulating layer 61, and the heating element 14 and the first and second mounting electrodes are overlapped. 18 and 19 are different from the fuse element 1 in that they are superimposed via third and fourth insulating layers 61 and 62.

  The first and second mounting electrodes 18 and 19 in the fuse element 60 are respectively provided in lower layer portions 18a and 19a stacked on the back surface 10b of the insulating substrate 10 and upper layer portions 18b and 19b stacked on the fourth insulating layer 62. And have.

  A third insulating layer 61 is laminated on the heating element extraction electrode 15 and the lower layer portions 18a and 19a. As a result, the heating element extraction electrode 15 is covered with the third insulating layer 61 except for a part of the insulating substrate 10 on the third side edge 10e side, and the lower layer portions 18a and 19a are formed on the first and second layers of the insulating substrate 10. 2 is covered with the third insulating layer 61 except for a part on the side surfaces 10c, 10d side. As the insulating material constituting the third insulating layer 61, for example, glass having high heat conduction efficiency can be used, and it can be formed by printing and baking (for example, 850 ° C. for 30 minutes) a glass paste. In the fuse element 60, the heating element 14 and the lower layer portions 18 a and 19 a of the first and second mounting electrodes 18 and 19 are superimposed on the heating element 14 via the third insulating layer 61. .

  The heating element 14 is laminated on the third insulating layer 61, and the heating element extraction electrode 15 not covered with the third insulating layer 61 and the heating element electrode 23 formed on the back surface 10b of the insulating substrate 10; It is connected. The heating element 14 has a fourth insulating layer 62 laminated thereon. The fourth insulating layer 62 prevents a short circuit between the heating element 14 and the first and second mounting electrodes 18 and 19, and at least the upper layer portions 18 b and 18 b of the first and second mounting electrodes 18 and 19. The heating element 14 on the region where 19b is formed is covered, and preferably the entire heating element 14 is covered. As an insulating material constituting the fourth insulating layer 62, for example, glass having high heat conduction efficiency can be used, and it can be formed by printing and baking (for example, 850 ° C. for 30 minutes) a glass paste.

  In the fuse element 60, the upper layer portions 18 b and 19 b of the first and second mounting electrodes 18 and 19 are superimposed on the heating element 14 via the fourth insulating layer 62. The heating element 14 is superimposed on the lower layer portions 18a and 19a and the upper layer portions 18b and 19b of the first and second mounting electrodes 18 and 19 through the third and fourth insulating layers 61 and 62, thereby The first and second mounting electrodes 18 and 19 are superposed in an insulated state.

  The upper layer portions 18 b and 19 b are connected to the lower layer portions 18 a and 19 a exposed from the third insulating layer 61. The upper layer portions 18b and 19b are external connection electrodes connected to a circuit board such as a protection circuit on which the fuse element 60 is mounted. The fuse element 60 is connected to a circuit board on which an external circuit is formed via the upper layer portions 18b and 19b of the first and second mounting electrodes 18 and 19, and the upper layer portion 18b, the lower layer portion 18a, the through hole 20, The path extending from the first electrode 11, the fusible conductor 13, the second electrode 12, the through hole 20, the lower layer part 19a, and the upper layer part 19b constitutes a part of the energization path of the external circuit.

  In such a fuse element 60, the heating element 14 and the heating element lead-out electrode 15 are overlapped via the third insulating layer 61, and the upper and lower layer portions 18ab, 19ab of the first and second mounting electrodes 18, 19 are overlapped. Are overlapped via the third and fourth insulating layers 61 and 62, so that a large space for forming the heating element 14 can be secured in the miniaturized insulating substrate 10. Therefore, the fuse element 60 can maximize the effective area of the heating element 14, and can melt the soluble conductor 13 quickly and stably. For example, in the fuse element 60, assuming that the size of the insulating substrate is reduced to 3 mm × 2 mm, the size of the heating element 14 can be increased to, for example, 2.5 mm × 1.4 mm. In addition, the fuse element 60 can secure a sufficient area of the upper layer portions 18b and 19b of the first and second mounting electrodes 18 and 19, and maximizes the mounting area on the circuit board, A predetermined rating can be provided.

  In addition, it is preferable that the heat generating body 14 is overlapped with a part or all of the through holes 20 and 21 formed in the heat generating body extraction electrode 15 and the lower layer portions 18a and 19a. Since the heating element 14 and the through holes 20 and 21 are overlapped, the first and second electrodes 11 and 12, the intermediate electrode 16, and the first and second electrodes can be heated even when the heat of the heating element 14 passes through the through holes 20 and 21. It is transmitted to the soluble conductor 13 mounted on the two electrodes 11 and 12 and the intermediate electrode 16, and the soluble conductor 13 can be blown out quickly.

  In addition, the heating element lead-out electrode 15 and the lower layer portions 18a and 19a of the first and second mounting electrodes 18 and 19 are replaced with the first through first holes of the insulating substrate 10 in place of the through holes 20 and 21 or both. A castellation may be provided on the third side edges 10c to 10e, and the first and second electrodes 11 and 12 and the intermediate electrode 16 may be electrically connected through the castellation.

  Such a fuse element 60 can be manufactured by the steps shown in FIGS. First, as shown in FIG. 16, the heating element extraction electrode 15, the lower layer portions 18 a and 19 a of the first and second mounting electrodes 18 and 19, and the heating element electrode 23 are formed on the back surface 10 b of the insulating substrate 10. Next, a part on the first and second side edges 10c and 10d side of the insulating substrate 10 on the lower layer portions 18a and 19a and a part on the third side edge 10e side of the insulating substrate 10 on the heating element extraction electrode 15 A third insulating layer 61 is formed except for.

  Next, as shown in FIG. 17, the heating element 14 is formed. The heating element 14 is formed on the third insulating layer 61 so as to overlap the heating element extraction electrode 15 and the lower layer portions 18a and 19a. The heating element 14 is connected to a part of the heating element extraction electrode 15 and the heating element electrode 23 that are not covered with the third insulating layer 61.

  Next, as shown in FIG. 18, a fourth insulating layer 62 is formed on the heating element 14. The fourth insulating layer 62 covers the entire heating element 14 and exposes the lower layer portions 18a and 19a except for a part of the insulating substrate 10 on the first and second side edges 10c and 10d side. .

  Then, as shown in FIG. 19, the upper layer portions 18 b and 19 b of the first and second mounting electrodes 18 and 19 are formed on the fourth insulating layer 62. The upper layer portions 18b and 19b are connected to the lower layer portions 18a and 19a at a part of the insulating substrate 10 on the first and second side edges 10c and 10d side.

[Fifth Embodiment]
20A and 20B, the fuse element is not provided with the lower layer portions 18a and 19a of the first and second mounting electrodes 18 and 19, and the first and second via the castellation 63. The two electrodes 11 and 12 may be connected to the upper layer portions 18b and 19b. The fuse element 65 shown in FIG. 20 is different from the fuse element 60 in that the lower layer portions 18a and 19a of the first and second mounting electrodes 18 and 19 are not provided. In this case, it is not necessary to provide the third insulating layer 61 that insulates the heating element 14 from the lower layer portions 18a and 19a, but an insulating layer is provided between the back surface 10b of the insulating substrate 10 and the heating element 14. Also good.

  Such a fuse element 65 can be manufactured by the steps shown in FIGS. First, as shown in FIG. 21, the heating element extraction electrode 15 and the heating element electrode 23 are formed on the back surface 10 b of the insulating substrate 10. Next, as shown in FIG. 22, the heating element 14 is formed. The heating element 14 is connected to the heating element extraction electrode 15 and the heating element electrode 23.

  Next, as shown in FIG. 23, a fourth insulating layer 62 is formed on the heating element 14. The fourth insulating layer 62 covers the entire heating element 14. Then, as shown in FIG. 24, the upper layer portions 18 b and 19 b of the first and second mounting electrodes 18 and 19 are formed on the fourth insulating layer 62. The upper layer portions 18b and 19b are formed by first and second electrodes formed on the surface 10a of the insulating substrate 10 through castellations 63 formed on the first and second side edges 10c and 10d of the insulating substrate 10, respectively. 11 and 12 are connected.

[Modification]
Here, in order to improve the rating of the fuse element in order to cope with a large current, not only the resistance of the fusible conductor 13 itself but also the first and second formed on the surface 10a of the insulating substrate 10 are reduced. A reduction in the resistance of the current path from the electrodes 11 and 12 to the first and second mounting electrodes 18 and 19 formed on the back surface 10b of the insulating substrate 10 is required.

  In the method of connecting the first and second electrodes 11 and 12 and the first and second mounting electrodes 18 and 19 via a castellation provided on the side surface of the insulating substrate 10, a plating layer formed on the castellation It is difficult to obtain a sufficient thickness, and the rating of the entire fuse element is defined by a current path from the first and second electrodes 11 and 12 to the first and second mounting electrodes 18 and 19, so that a large current can be obtained. There is an inconvenience that it becomes difficult to correspond.

  Therefore, as described above, in the fuse element to which the present technology is applied, the first and second electrodes 11 and 12 are provided on the back surface 10b through the through holes 20 penetrating the insulating substrate 10, respectively. The first and second mounting electrodes 18 and 19 are connected. The first and second electrodes 11 and 12 and the through hole 20 connecting the first and second mounting electrodes 18 and 19 constitute a part of the energization path of the fuse elements 1, 50 and 60, and have a current rating. Therefore, the first electrode 11 and the first mounting electrode 18, and the second electrode 12 and the second mounting electrode 19 are provided therein. A conductive layer to be connected is formed.

[Fuse element 70]
In addition to the fuse elements 1, 50 and 60 in which the heating element 14 is formed on the back surface of the insulating substrate 10 as a fuse element in which the conductive through hole 20 in which the conductive layer is formed is formed, FIG. As shown in FIG. 26, the present invention can also be applied to a fuse element 70 in which a heating element is formed on the surface of an insulating substrate. In the description of the fuse element 70 described below, the same members as those of the above-described fuse elements 1, 50, 60 are denoted by the same reference numerals, and the details thereof are omitted.

  The fuse element 70 includes the insulating substrate 10, the heating element 14 laminated on the insulating substrate 10 and covered with the insulating layer 17, and the first electrode 11 and the second electrode 12 formed on both ends of the insulating substrate 10. An intermediate electrode 16 laminated on the insulating layer 17 so as to overlap the heating element 14, both ends connected to the first and second electrodes 11, 12 respectively, and a central portion connected to the intermediate electrode 16 A molten conductor 13 is provided.

[First and second electrodes]
The first and second electrodes 11 and 12 are connected to the first and second mounting electrodes 18 and 19 which are external connection electrodes provided on the back surface 10b through the through holes 20 penetrating the insulating substrate 10, respectively. Has been. The first and second electrodes 11 and 12 and the through hole 20 connecting the first and second mounting electrodes 18 and 19 constitute a part of the energization path of the fuse element 70 and are elements that determine the current rating. Therefore, the conductive layer has a predetermined dimension (for example, 0.3 mmφ) and connects the first electrode 11 and the first mounting electrode 18, and the second electrode 12 and the second mounting electrode 19 inside. Is formed.

[Heating element]
The heating element 14 can be formed by forming a pattern on the surface 10a of the insulating substrate 10 using a screen printing technique and baking it. The heating element 14 has one end connected to the heating element extraction electrode 15 and the other end connected to the heating element electrode 23.

  In the fuse element 70, an insulating layer 17 is disposed so as to cover the heating element 14, and an intermediate electrode 16 is formed so as to face the heating element 14 through the insulating layer 17. In order to efficiently transmit the heat of the heating element 14 to the soluble conductor 13, an insulating layer 17 may be laminated between the heating element 14 and the insulating substrate 10. As the insulating layer 17, for example, glass can be used.

  One end of the intermediate electrode 16 is connected to a part of the heating element extraction electrode 15 exposed from the insulating layer 17 and is connected to one end of the heating element 14 through the heating element extraction electrode 15. The heating element extraction electrode 15 is formed on the third side surface 10 e side of the insulating substrate 10, and the heating element electrode 23 is formed on the fourth side surface 10 f side of the insulating substrate 10. The heating element electrode 23 is connected to an external connection electrode 23a formed on the back surface 10b of the insulating substrate 10 via a castellation 71 formed on the fourth side surface 10f.

  The heating element 14 is connected to an external circuit formed on the circuit board 2 through the external connection electrode 23a by mounting the fuse element 70 on the circuit board 2. The heating element 14 can be connected to the first and second electrodes 11 and 12 by being energized through the external connection electrode 23a at a predetermined timing for cutting off the energization path of the external circuit and generating heat. The molten conductor 13 can be blown. Moreover, since the heat generating body 14 also cut | disconnects its energization path | route when the soluble conductor 13 blows, heat_generation | fever stops.

  Also in the fuse element 70, a cap 24 that protects the inside is mounted on the surface 10 a of the insulating substrate 10.

  According to such a fuse element 70, the first and second electrodes 11 and 12 are connected to the first and second mounting electrodes 18 and 19 via the conductive through holes 20, respectively. The thickness of the conductive layer can be sufficiently ensured as compared with the case of connection through a conventional castellation, and the first and second electrodes 11 and 12 and the first and second mounting electrodes 18 and 18 can be secured. It is possible to reduce the resistance of the current-carrying path with respect to 19. Therefore, the fuse element 70 can be used for a large current application without the current conduction path hindering the improvement of the rating.

  In the fuse element 70, the heating element electrode 23 serving as an energization path to the heating element 14 is connected to the external connection electrode 23 a formed on the back surface 10 b of the insulating substrate 10 via the castellation 71. As a result, as shown in FIG. 27, when the fuse element 70 is solder-connected to the external circuit board 72, the fillet 73 is formed in the castellation 71, so that the external connection electrode 23a is surface-connected. Compared to the above, the mounting strength on the external circuit board 72 can be improved. Further, in the process of mounting the fuse element 70 on the external circuit board 72, by confirming the fillet 73, it is possible to easily determine that the fuse element 70 is securely connected by visual inspection or image inspection.

  Further, in the fuse element 70, the current-carrying path between the heating element electrode 23 and the external connection electrode 23a is formed by the castellation 71, so that the heating element electrode 23 can be made narrower than when the conductive through hole is formed. As a result, the entire device can be reduced in size.

  Further, the fuse element 70 may connect the heating element electrode 23 and the external connection electrode 23a via a side electrode formed on the side surface of the insulating substrate 10 by printing or the like. Also in this case, as in the case of connection via the castellation 71, the connection strength can be improved by forming the fillet 73, and the connection can be easily confirmed. Furthermore, the heating element electrode 23 can be narrowed compared to the case where the conductive through hole is formed, and the entire element can be reduced in size.

  Since the energization path to the heating element 14 is not an element that determines the rating of the fuse element 70 unlike the energization path of the fusible conductor 13, it may have a higher resistance than the energization path of the fusible conductor 13 (for example, (Several Ω order). Therefore, the fuse element 70 does not impair the improvement in rating even when the castellation 71 or the side electrode is used. In general, the formation of the castellation 71 has a higher mounting strength, and the manufacturing process is simpler and more advantageous in terms of manufacturing cost, as compared with the case where side electrodes are formed on the side surface of the insulating substrate 10 by printing or the like. . On the other hand, in order to form the castellation 71, it is necessary to provide recesses in the heating element electrode 23 and the external connection electrode 23a, whereas in the side electrode, the heating element electrode 23 and the external connection electrode 23a have a minimum necessary area. Therefore, it is easy to reduce the size.

[Castellation]
In the fuse element 70, as shown in FIG. 28, a castellation 74 may be further formed on the first and second electrodes 11 and 12, depending on conditions such as a request for downsizing and a manufacturing cost. In this case, it is preferable to provide the castellation 74 and the conductive through hole 20 with a predetermined interval (for example, at least half the opening diameter of the conductive through hole 20) to ensure strength. In the fuse element 70, the first and second electrodes 11 and 12 are provided with a castellation 74 in addition to the conductive through hole 20, thereby further reducing the conduction resistance and improving the mounting strength by forming a fillet. In addition, confirmation of mounting on the external circuit board 72 can be easily performed by confirming the fillet.

[Independent electrode]
In addition, as shown in FIG. 29, the fuse element 70 has the first and second electrodes 11 and 12 and the heating element 14 on the surface 10a of the insulating substrate 10 in order to improve the mounting strength to the external circuit board 72. The first independent terminal 75 that does not participate in the conduction of the first insulating terminal 75 is provided, and the second independent terminal 76 that does not participate in the conduction with the first and second electrodes 11 and 12 and the heating element 14 is provided on the back surface 10b of the insulating substrate 10. The first and second independent terminals 75 and 76 may be connected via a castellation 77.

  By providing the first and second independent terminals 75 and 76 connected via the castellation 77, at least one fillet is formed. Therefore, the fuse element 70 has a mounting strength to the external circuit board 72. Can be improved.

  In the fuse element 70, the first and second independent terminals 75 and 76 may be connected by a side electrode provided on the side surface of the insulating substrate, and a fillet may be formed along the side electrode.

DESCRIPTION OF SYMBOLS 1 Fuse element, 10 Insulating substrate, 11 1st electrode, 12 2nd electrode, 13 Soluble conductor, 14 Heating body, 15 Heating body extraction electrode, 16 Intermediate electrode, 17 Insulating layer, 18 1st mounting electrode, 18a Lower layer, 18b Upper layer, 19 Second mounting electrode, 19a Lower layer, 19b Upper layer, 20 Through hole, 21 Through hole, 23 Heating element electrode, 24 Cap, 30 Battery pack, 31-34 Battery cell, 35 Battery stack, 36 detection circuit, 37 current control element, 40 charge / discharge control circuit, 41, 42 current control element, 43 control unit, 45 charging device, 50 fuse element, 51 first insulating layer, 52 second insulating layer 53 castellation 55 fuse element 60 fuse element 61 third insulating layer 62 fourth insulating layer 63 Castellation, 65 fuse element, 70 fuse element, 71 castellation, 72 external circuit board, 73 fillet, 74 castellation, 75, first independent terminal, 76 second independent terminal, 77 castellation

Claims (25)

An insulating substrate;
A first electrode and a second electrode formed on the surface of the insulating substrate;
A fusible conductor connected between the first and second electrodes;
A heating element that is formed on the back surface of the insulating substrate, generates heat when energized, and melts the soluble conductor;
A back electrode formed on the back surface of the insulating substrate,
A fuse element in which the heating element and the back electrode are overlapped via an insulating layer.   The fuse element according to claim 1, wherein the back electrode is a heating element extraction electrode connected to the heating element.   3. The fuse element according to claim 2, wherein the heating element extraction electrode is connected to an intermediate electrode formed on the surface of the insulating substrate and connected to the soluble conductor via a conductive through hole penetrating the insulating substrate. .   4. The fuse element according to claim 3, wherein the heating element is overlapped with a part or all of the conductive through hole.   The fuse element according to any one of claims 2 to 4, wherein the heating element extraction electrode is connected to the intermediate electrode via a castellation provided on a side surface of the insulating substrate.   The fuse element of any one of Claims 2-5 laminated | stacked in order of the said heat generating body extraction electrode, the said insulating layer, and the said heat generating body from the back surface of the said insulating substrate.   The fuse element according to claim 6, wherein the heating element is covered with a protective layer.   2. The fuse element according to claim 1, wherein the back surface electrodes are first and second mounting electrodes that are connected to the first and second electrodes and are mounted on a circuit board.   9. The first and second mounting electrodes are respectively connected to the first and second electrodes formed on the surface of the insulating substrate through conductive through holes that penetrate the insulating substrate. The fuse element as described.   The fuse element according to claim 9, wherein the heating element is overlapped with a part or all of the conductive through hole.   The said 1st, 2nd mounting electrode is connected to the said 1st, 2nd electrode via the castellation provided in the side surface of the said insulated substrate, The any one of Claims 8-10. Fuse element. The first and second mounting electrodes have a lower layer portion provided between the back surface of the insulating substrate and the heating element, and an upper layer portion connected to the lower layer portion and mounted on the circuit board. ,
From the back surface of the insulating substrate, the lower layer portion of the first and second mounting electrodes, the first insulating layer, the heating element, the second insulating layer, and the upper layer portion of the first and second mounting electrodes. The fuse element of any one of Claims 8-11 laminated | stacked in order. The first insulating layer is formed between the lower layer portions of the first and second mounting electrodes,
The fuse element according to claim 12, wherein the heating element is formed on the first insulating layer. The first and second mounting electrodes are composed of an upper layer portion connected to the first and second electrodes and mounted on the circuit board,
The fuse element according to claim 11, wherein the heating element, the second insulating layer, and the upper layer portion are laminated in this order from the back surface of the insulating substrate.   2. The back electrode is a heating element extraction electrode connected to the heating element and first and second mounting electrodes connected to the first and second electrodes and mounted on a circuit board. Fuse element. The heating element extraction electrode is connected to an intermediate electrode formed on the surface of the insulating substrate and connected to the soluble conductor through a conductive through hole penetrating the insulating substrate.
16. The first and second mounting electrodes are respectively connected to the first and second electrodes formed on the surface of the insulating substrate through conductive through holes penetrating the insulating substrate. The fuse element as described.   The fuse element according to claim 16, wherein the heating element is overlapped with a part or all of the conductive through hole. The heating element extraction electrode is connected to the intermediate electrode via a castellation provided on a side surface of the insulating substrate,
The fuse element according to claim 16 or 17, wherein the first and second mounting electrodes are connected to the first and second electrodes via a castellation provided on a side surface of the insulating substrate. The first and second mounting electrodes have a lower layer portion provided between the back surface of the insulating substrate and the heating element, and an upper layer portion connected to the lower layer portion and mounted on the circuit board. ,
The heating element lead-out electrode and the lower layer portion of the first and second mounting electrodes, the third insulating layer, the heating element, the fourth insulating layer, and the first and second mountings from the back surface of the insulating substrate. The fuse element of any one of Claims 15-18 laminated | stacked in order of the said upper-layer part of an electrode. The first and second mounting electrodes are composed of an upper layer portion connected to the first and second electrodes and mounted on the circuit board,
19. The fuse element according to claim 18, wherein the heating element extraction electrode, the heating element, the fourth insulating layer, and the upper layer portion are laminated in this order from the back surface of the insulating substrate. An insulating substrate;
A first electrode and a second electrode formed on the surface of the insulating substrate;
A fusible conductor connected between the first and second electrodes;
A heating element that is formed on the insulating substrate and generates heat when energized to melt the soluble conductor;
A first external connection electrode and a second external connection electrode formed on the back surface of the insulating substrate;
Either or both of the first electrode and the first external connection electrode, and the second electrode and the second external connection electrode are connected via a conductive through hole penetrating the insulating substrate. Fuse element.   Either or both of the first electrode and the first external connection electrode, and the second electrode and the second external connection electrode are casted or a side electrode provided on a side surface of the insulating substrate. The fuse element according to claim 21, wherein the fuse elements are connected via each other. The heating element is formed on the surface of the insulating substrate,
A heating element extraction electrode provided on the surface of the insulating substrate and connected to the heating element;
Between the first and second electrodes, an intermediate electrode that is superimposed on the heating element via an insulating layer and connected to the heating element lead-out electrode and the soluble conductor,
The fuse element according to claim 21 or 22, wherein the heating element extraction electrode is provided with a castellation extending over a back surface of the insulating substrate. The heating element is formed on the back surface of the insulating substrate,
An intermediate electrode provided between the first and second electrodes and connected to the soluble conductor;
A heating element extraction electrode provided on the back surface of the insulating substrate and connected to the heating element;
The intermediate electrode and the heating element extraction electrode are connected to each other through a conductive through hole penetrating the insulating substrate, a castellation, or a side electrode provided on a side surface of the insulating substrate. Fuse element. A first independent terminal not involved in conduction with the first and second electrodes and the heating element is provided on the surface of the insulating substrate;
A second independent terminal not involved in conduction with the first and second electrodes and the heating element is provided on the back surface of the insulating substrate;
The fuse element according to any one of claims 21 to 24, wherein the first and second independent terminals are connected via castellation or a side electrode provided on a side surface of the insulating substrate.

Images