JP2018018835A - Protection element and fuse element - Google Patents

Abstract

PROBLEM TO BE SOLVED: To maintain stable fusing characteristics by preventing a fuse element from being deformed even when exposed to a high temperature environment such as reflow mounting.SOLUTION: The protection element includes: an insulating substrate 11; a heating element 14; a first electrode 12 and a second electrode 13 formed at both ends of the insulating substrate 11; a fuse element 17 whose both ends are connected to the first and second electrodes 12 and 13 via a connection material 21; and a regulating wall 82 for regulating wet spreading of a solder for connection with a circuit board to the first electrode 12 and the second electrode 13.SELECTED DRAWING: Figure 9

Description

  The present invention relates to a protection element and a fuse element that are mounted on a current path and use a fuse element that cuts off the current path by fusing due to self-heating when a current exceeding the rating flows, or heat generated by a heating element, and in particular heating. The present invention relates to a protective element and a fuse element in which variation in fusing characteristics of the fuse element is suppressed even when exposed to the environment.

  Conventionally, a fuse element that melts by self-heating when a current exceeding the rating flows and interrupts the current path has been used. As the fuse element, for example, a holder-fixed fuse in which solder is enclosed in a glass tube, a chip fuse in which an Ag electrode is printed on the surface of a ceramic substrate, or a screw fixing in which a part of a copper electrode is thinned and incorporated in a plastic case or Plug-in fuses are often used.

  However, it has been pointed out that the above-mentioned existing fuse element cannot be surface-mounted by reflow, has a low current rating, and is inferior in quick disconnection when the rating is increased by increasing the size.

  Further, when a fast-acting fuse element for reflow mounting is assumed, generally, a high melting point solder containing Pb having a melting point of 300 ° C. or more is preferable for the fuse element from the viewpoint of fusing characteristics so as not to melt by the heat of reflow. However, in the RoHS directive and the like, the use of Pb-containing solder is only limitedly recognized, and it is considered that the demand for Pb-free solder will increase in the future.

  In view of such a demand, as shown in FIG. 17, a fuse element 100 is used in which a high melting point metal layer 102 such as silver or copper is laminated on a low melting point metal layer 101 such as Pb-free solder. According to such a fuse element 100, surface mounting by reflow is possible, it is excellent in mountability to the fuse element, and it is possible to cope with a large current by raising the rating by being coated with a high melting point metal. The current path can be quickly interrupted by the erosion action of the high melting point metal by the low melting point metal.

JP 2013-229293 A

  The fuse element 100 can be manufactured by forming the high melting point metal layer 102 on the low melting point metal layer 101 using a plating technique. For example, the fuse element 100 can be manufactured efficiently by easily producing an element film by applying Ag plating to a long solder foil, and cutting it in accordance with the size at the time of use. .

  Then, for example, as shown in FIG. 18, the fuse element 100 is connected to the first and second electrodes 104 and 105 formed on the insulating substrate 103 with a connection material such as a connection solder 106 therebetween. As a result, the first and second electrodes 104 and 105 are electrically connected. The fuse element 100 can be efficiently mounted on the circuit board by being mounted on the first and second electrodes 104 and 105 via the connecting solder 106 and then passing through a reflow furnace.

  Here, in the fuse element 100 having a laminated structure of the conventional low melting point metal layer 101 and the high melting point metal layer 102, the low melting point metal covered with the high melting point metal is exposed on the cut surface of the element film. Under a high temperature environment such as reflow mounting, the solder for mounting on the molten circuit board wets and spreads on the first and second electrodes 104 and 105 on the surface of the insulating substrate, so that the low melting point metal flows out by the surface tension, In actual use, it may not be possible to maintain the predetermined fusing characteristics, such as not fusing depending on the predetermined temperature and overcurrent, or the fusing time will be extended, and conversely fusing at a temperature lower than the predetermined temperature or current value. There is.

  Therefore, an object of the present invention is to provide a protection element and a fuse element that can prevent deformation of the fuse element and maintain stable fusing characteristics even when exposed to a high temperature environment such as reflow mounting. .

  In order to solve the above-described problems, a protection element according to the present invention includes an insulating substrate, a heating element, a first electrode and a second electrode formed on the insulating substrate, and both ends of the first electrode. And a fuse element connected to the second electrode via a connecting material, and a regulation wall for restricting wetting and spreading of the solder for connection to the circuit board to the fuse element.

  Further, the fuse element according to the present invention includes an insulating substrate, a first electrode and a second electrode formed on the insulating substrate, and connecting materials for the first electrode and the second electrode at both ends. And a regulating wall that regulates the wetting and spreading of the solder for connection to the circuit board to the fuse element.

  According to the present invention, by providing the regulating wall, even when the connecting solder provided on the connection electrode of the external circuit board spreads wet on the first and second electrodes, it is dammed by the regulating wall, Contact with the fuse element can be prevented.

1A and 1B are diagrams showing a protective element to which the present invention is applied, in which FIG. 1A is a plan view with a cover member omitted, and FIG. 1B is a cross-sectional view taken along line A-A ′. FIG. 2 is a perspective view showing the fuse element. FIG. 3 is a circuit diagram illustrating an example of a circuit configuration of the battery pack. 4A and 4B are circuit diagrams of the protection element, where FIG. 4A shows before the fuse element is blown, and FIG. 4B shows the fuse element after the fuse element is blown. 5A and 5B are views showing a modification of the protection element to which the present invention is applied, in which FIG. 5A is a plan view with the cover member omitted, and FIG. 5B is a cross-sectional view taken along line A-A ′. 6A and 6B are views showing a modification of the protective element to which the present invention is applied, in which FIG. 6A is a plan view with the cover member omitted, and FIG. 6B is a cross-sectional view taken along line A-A ′. 7A and 7B are views showing a modification of the protection element to which the present invention is applied. FIG. 7A is a plan view showing the cover member omitted, and FIG. 7B is a cross-sectional view taken along line A-A ′. 8A and 8B are views showing a modification of the protection element to which the present invention is applied, in which FIG. 8A is a plan view with the cover member omitted, and FIG. 8B is a cross-sectional view taken along line A-A ′. 9A and 9B are views showing a modification of the protection element to which the present invention is applied, in which FIG. 9A is a plan view with the cover member omitted, and FIG. 9B is a cross-sectional view taken along line A-A ′. 10A and 10B are diagrams showing a fuse element to which the present invention is applied, in which FIG. 10A is a plan view with the cover member omitted, and FIG. 10B is a cross-sectional view taken along line A-A ′. FIG. 11 is a circuit diagram of the fuse element, where (A) shows before the fuse element is blown and (B) shows after the fuse element is blown. 12A and 12B are views showing a modification of the fuse element to which the present invention is applied, in which FIG. 12A is a plan view in which a cover member is omitted, and FIG. 12B is a cross-sectional view along A-A ′. 13A and 13B are views showing a modification of the fuse element to which the present invention is applied. FIG. 13A is a plan view showing the cover member omitted, and FIG. 13B is a cross-sectional view taken along line A-A ′. 14A and 14B are views showing a modification of the fuse element to which the present invention is applied. FIG. 14A is a plan view showing the cover member omitted, and FIG. 14B is a cross-sectional view taken along line A-A ′. 15A and 15B are diagrams showing a modification of the fuse element to which the present invention is applied, in which FIG. 15A is a plan view showing the cover member omitted, and FIG. 15B is a cross-sectional view taken along line A-A ′. 16A and 16B are views showing a modification of the fuse element to which the present invention is applied. FIG. 16A is a plan view showing the cover member omitted, and FIG. 16B is a cross-sectional view taken along line A-A ′. FIG. 17 is a cross-sectional view showing a fuse element in which a low melting point metal layer is covered with a high melting point metal layer. 18A and 18B are diagrams showing a conventional protection element, in which FIG. 18A is a plan view in which a cover member is omitted, and FIG. 18B is a cross-sectional view along X-X ′.

  Hereinafter, a protection element and 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.

[Configuration of protection element]
As shown in FIGS. 1A and 1B, a protection element 10 to which the present invention is applied includes an insulating substrate 11, a heating element 14 laminated on the insulating substrate 11 and covered with an insulating layer 15, and an insulating substrate. 11, the first electrode 12 and the second electrode 13 formed at both ends, the heating element extraction electrode 16 stacked on the insulating layer 15 so as to overlap the heating element 14, and both ends of the first and second electrodes. The fuse element 17 is connected to each of the electrodes 12 and 13, and the central portion is connected to the heating element extraction electrode 16. A cover member 18 that protects the inside is mounted on the insulating substrate 11.

  The insulating substrate 11 is formed in, for example, a substantially square shape using an insulating member such as alumina, glass ceramics, mullite, zirconia. In addition, the insulating substrate 11 may be made of a material used for a printed wiring board such as a glass epoxy board or a phenol board.

  First and second electrodes 12 and 13 are formed on opposite ends of the insulating substrate 11. The first and second electrodes 12 and 13 are each formed of a conductive pattern such as Ag or Cu. The first and second electrodes 12 and 13 are continuous from the front surface 11a of the insulating substrate 11 with the first and second external connection electrodes 12a and 13a formed on the back surface 11b through castellation. . The protective element 10 is configured such that the first and second external connection electrodes 12a and 13a formed on the back surface 11b are connected to connection electrodes provided on the external circuit board on which the protective element 10 is mounted, thereby It is incorporated into a part of the current path formed above.

  The heating element 14 is a conductive member that has a relatively high resistance value and generates heat when energized, and is made of, for example, nichrome, W, Mo, Ru, or the like or a material containing these. The heating element 14 is obtained by mixing a powdery body of these alloys, compositions, or compounds with a resin binder or the like, forming a paste on the insulating substrate 11 using a screen printing technique, and firing it. Etc. can be formed.

  In addition, the protection element 10 is provided with an insulating layer 15 so as to cover the heating element 14, and a heating element extraction electrode 16 is formed so as to face the heating element 14 through the insulating layer 15. The heating element lead electrode 16 is connected to the fuse element 17, whereby the heating element 14 is superimposed on the fuse element 17 via the insulating layer 15 and the heating element lead electrode 16. The insulating layer 15 is provided to protect and insulate the heating element 14 and to efficiently transmit the heat of the heating element 14 to the fuse element 17 and is made of, for example, a glass layer. In addition, the protective element 10 may laminate an insulating layer 15 between the heating element 14 and the insulating substrate 11 in order to efficiently transmit the heat of the heating element 14 to the fuse element 17.

  In the protection element 10, the heating element 14 may be formed on the back surface 11b opposite to the front surface 11a of the insulating substrate 11 on which the first and second electrodes 12 and 13 are formed. It may be formed adjacent to the first and second electrodes 12 and 13 on the surface 11a. Further, the protection element 10 may have the heating element 14 formed inside the insulating substrate 11.

  The heating element 14 has one end connected to the heating element extraction electrode 16 and the other end connected to the heating element electrode 19. The heating element lead electrode 16 is formed on the surface 11 a of the insulating substrate 11 and is laminated on the insulating layer 15 so as to face the heating element 14 and the lower layer portion 16 a connected to the heating element 14, and the fuse element 17. And an upper layer portion 16b connected to the. Thus, the heating element 14 is electrically connected to the fuse element 17 via the heating element extraction electrode 16. Note that the heating element extraction electrode 16 is disposed opposite to the heating element 14 with the insulating layer 15 interposed therebetween, whereby the fuse element 17 can be melted and the molten conductor can be easily aggregated.

  The heating element electrode 19 is formed on the front surface 11a of the insulating substrate 11, and is continuous with the heating element power supply electrode 19a formed on the back surface 11b of the insulating substrate 11 through castellation.

[Fuse element]
The protection element 10 has a fuse element 17 connected from the first electrode 12 to the second electrode 13 via the heating element extraction electrode 16. The fuse element 17 is used as a fusible conductor of the protection element 10. In normal use, the fuse element 17 conducts between the first and second electrodes 12 and 13, and part of the current path of the external circuit in which the protection element 10 is incorporated. Configure. The fuse element 17 is blown by self-heating (Joule heat) when a current exceeding the rating is applied, or is blown by the heat generated by the heating element 14 to cut off between the first and second electrodes 12 and 13. .

  The fuse element 17 is made of a material that is quickly melted by heat generated by the heat generating element 14 or self-heating, and is formed by laminating a low melting point metal layer 23 and a high melting point metal layer 24. As the low melting point metal, it is preferable to use solder such as Pb-free solder, and as the high melting point metal, it is preferable to use Ag, Cu or an alloy containing these as a main component. By including the high melting point metal and the low melting point metal, when the protective element 10 is reflow mounted, even if the reflow temperature exceeds the melting temperature of the low melting point metal layer and the low melting point metal melts, the fuse element 17 Will not blow out.

  As shown in FIG. 2, the fuse element 17 may have an inner layer made of a low melting point metal and an outer layer made of a high melting point metal. By using a soluble conductor in which the entire surface of the inner low melting point metal layer 23 is covered with the outer high melting point metal layer 24, even when a low melting point metal having a melting point lower than the reflow temperature is used, The outflow of the low melting point metal to the outside can be suppressed. Further, when the inner layer low melting point metal melts, the outer layer high melting point metal is also eroded (soldered) and can be quickly melted.

  The fuse element 17 can be manufactured by forming a high melting point metal on the low melting point metal layer 23 using a plating technique. For example, the fuse element 17 can be manufactured efficiently by using an Ag film on the surface of a long solder foil, and can be efficiently manufactured by cutting according to the size when used. Can do. Further, the fuse element 17 may form an element film made of a laminate of the low-melting-point metal layer 23 and the high-melting-point metal layer 24 by using another known lamination technique or film formation technique.

  Since such a fuse element 17 is formed by cutting into a size that uses an element film, a pair of opposing end surfaces (cut surfaces) are surrounded by a refractory metal layer 24. The exposed surface 25 is exposed. In addition, the fuse element 17 has a covered surface 26 in which a pair of opposite side surfaces orthogonal to the exposed surface 25 are covered with the refractory metal layer 24.

  The fuse element 17 may have a laminated structure in which a low melting point metal layer 23 and a high melting point metal layer 24 are laminated. Moreover, it is good also as a multilayered structure of four or more layers by which the low melting metal layer 23 and the high melting metal layer 24 were laminated | stacked alternately.

  Further, the fuse element 17 preferably has a volume of the low melting point metal larger than that of the high melting point metal. As a result, the fuse element 17 can be effectively blown in a short time by the erosion of the refractory metal layer.

  The fuse element 17 can be easily connected by reflow soldering via the connection solder 21 provided on the first and second electrodes 12 and 13 and the heating element lead electrode 16.

  The protection element 10 is provided with the fuse element 17 at a position overlapping the heating element 14 via the insulating layer 15 and the heating element extraction electrode 16, so that the heat generated by the heating element 14 is efficiently supplied to the fuse element 17. It can be reported and blown out quickly.

  Note that the protective element 10 is required to reduce the conductor resistance of the fuse element 17 in order to improve the rating and allow more current to flow. Therefore, the protective element 10 is increased in size by increasing the volume of the fuse element 17.

  Here, the fuse element 17 is arranged so that the low melting point metal layer 23 exposed outward from the exposed surface 25 does not touch the connecting solder 21. For example, as shown in FIG. 1, the fuse element 17 has exposed surfaces 25 on both sides in the energizing direction between the first and second electrodes 12 and 13, and on the first and second electrodes 12 and 13. A region other than the exposed surface 25 is connected by the connecting solder 21 provided on the surface. Thereby, in the fuse element 17, a gap is formed between the exposed surface 25 and the first and second electrodes 12 and 13, and the exposed surface 25 is connected to the connecting solder 21 and the first and second electrodes 12. , 13 is not touched.

  Thus, since the exposed surface 25 of the fuse element 17 is isolated from the conductors such as the first and second electrodes 12 and 13 and the connecting solder 21 by the insulator (gap), a high temperature environment such as a reflow process is performed. Below, it is possible to prevent the low melting point metal exposed from the exposed surface 25 from getting wet on the first and second electrodes 12 and 13 or being attracted by the surface tension of the connecting solder 21. . Accordingly, the outer shape of the fuse element 17 is deformed due to the outflow of the low melting point metal, so that the fuse element 17 is not blown by a predetermined temperature or overcurrent, or the fusing time is extended. It is possible to prevent fluctuations in the fusing characteristics.

[flux]
Further, the protection element 10 may be coated with a flux 22 on the front surface or the back surface of the fuse element 17 in order to prevent the fuse element 17 from being oxidized, remove the oxide at the time of fusing, and improve the fluidity of the solder. By coating the flux 22, the wettability of the fuse element 17 (for example, solder) is enhanced during the actual use of the protection element 10, and the oxide is removed while the fuse element 17 is dissolved, thereby quickly fusing. Can be improved.

  Further, by coating the flux 22, even when an antioxidant film such as Pb-free solder mainly composed of Sn is formed on the surface of the fuse element 17, the oxide of the antioxidant film can be removed. Thus, the oxidation of the fuse element 17 can be effectively prevented, and the fast fusing property can be maintained and improved.

  The first and second electrodes 12 and 13, the heating element extraction electrode 16 and the heating element electrode 19 are formed by a conductive pattern such as Ag or Cu, and the surface is appropriately Sn-plated, Ni / Au plated, Ni A protective layer such as / Pd plating or Ni / Pd / Au plating is preferably formed. Thereby, the surface oxidation can be prevented, and the erosion of the first and second electrodes 12 and 13 and the heating element extraction electrode 16 by the connection material such as the connection solder 21 of the fuse element 17 can be suppressed.

[Cover member]
Further, the protective element 10 is provided with a cover member 18 on the surface 11a of the insulating substrate 11 provided with the fuse element 17 so as to protect the inside and prevent the molten fuse element 17 from scattering. The cover member 18 can be formed of an insulating member such as various engineering plastics and ceramics. The cover member 18 is connected to the surface 11 a of the insulating substrate 11 by an insulating adhesive, and thereby covers the fuse element 17.

  In such a protection element 10, an energization path to the heating element 14 that reaches the heating element feeding electrode 19 a, the heating element electrode 19, the heating element 14, the heating element extraction electrode 16, and the fuse element 17 is formed. Further, the protection element 10 is connected to an external circuit in which the heating element electrode 19 energizes the heating element 14 via the heating element feeding electrode 19a, and the energization across the heating element electrode 19 and the fuse element 17 is controlled by the external circuit. .

  Further, the protection element 10 constitutes a part of a current-carrying path to the heating element 14 by connecting the fuse element 17 to the heating element extraction electrode 16. Therefore, when the fuse element 17 is melted and the connection with the external circuit is interrupted, the protective element 10 can also stop the heat generation because the energization path to the heating element 14 is also interrupted.

[How to use protection elements]
Next, usage forms of the protection elements 10 will be described. As shown in FIG. 3, the protection element 10 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 protection element 10 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 voltages 31 to 34 and a current control element 37 that controls the operation of the protection element 10 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 battery pack 30 charged by the charging device 45 can operate the electronic device by connecting the positive terminal 30a and the negative terminal 30b to the electronic device operated by the 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 operations 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 control the gate voltage by the control unit 43 to control conduction and interruption of the current path of the battery stack 35. . 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 protection element 10 is connected to, for example, 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 configured by, for example, an FET, and when the voltage value of the battery cells 31 to 34 exceeds a predetermined overdischarge or overcharge state by a detection signal output from the detection circuit 36, the protection element 10 is operated to control the charge / discharge current path of the battery stack 35 to be cut off regardless of the switch operation of the current control elements 41 and 42.

  In the battery pack 30 having the above configuration, the protection element 10 to which the present invention is applied has a circuit configuration as shown in FIG. That is, the protective element 10 is energized through the connecting point between the fuse element 17 and the fuse element 17 connected in series across the first and second external connection electrodes 12 a and 13 a via the heating element extraction electrode 16. The circuit configuration includes a heating element 14 that melts the fuse element 17 by generating heat. In the protection element 10, for example, the fuse element 17 is connected in series on the charge / discharge current path of the battery pack 30 via the first and second external connection electrodes 12 a and 13 a, and the heating element 14 is connected to the heating element electrode 19. Is connected to the current control element 37 through the heating element power supply electrode 19a. The first external connection electrode 12 a of the protection element 10 is connected to one open end side of the battery stack 35, and the second external connection electrode 13 a is connected to the positive electrode terminal 30 a side of the battery pack 30.

[Fusing process]
In the protection element 10 having such a circuit configuration, when the current path of the battery pack 30 needs to be interrupted, the heating element 14 is energized and heated by the current control element 37 provided in the battery pack 30. As a result, the protection element 10 is melted by the heat generated by the heating element 14, so that the fuse element 17 incorporated on the current path of the battery pack 30 is melted, and the molten conductor of the fuse element 17 is heated by the heating element lead electrode 16 having high wettability. The fuse element 17 is blown by being drawn to the first and second electrodes 12 and 13. As a result, the protection element 10 surely melts the space between the first electrode 12 to the heating element extraction electrode 16 to the second electrode 13 (FIG. 4B), and interrupts the current path of the battery pack 30. Can do. Further, when the fuse element 17 is melted, power supply to the heating element 14 is stopped.

  The protection element 10 of the present invention is not limited to use in a battery pack of a lithium ion secondary battery, but can be applied to various uses that require interruption of a current path by an electric signal.

[Modification 1]
Next, modifications of the protection element to which the present invention is applied will be described. In the following description, the same members as those of the protection element 10 described above are denoted by the same reference numerals and the details thereof are omitted.

  In the protection element to which the present invention is applied, the exposed surface 25 of the fuse element 17 may be supported by a material that does not have wettability with respect to the low melting point metal. In the protection element 50 shown in FIG. 5, the exposed surface 25 is directed to both sides in the energizing direction of the fuse element 17 between the first and second electrodes 12 and 13, and the exposed surface 25 of the fuse element 17 is insulated by an insulator 51. I support it. The insulator 51 can be formed using an insulating material having no wettability with respect to solder such as glass, solder resist, and insulating adhesive, and is formed on the first and second electrodes 12 and 13 by printing or the like. can do. The insulator 51 is formed along the extending direction of the exposed surface 25 of the fuse element 17 disposed on the first and second electrodes 12 and 13.

  When the exposed surface 25 is supported by the insulator 51, the fuse element 17 is spread over the first and second electrodes 12 and 13 by melting the connecting solder 21 in a high temperature environment such as a reflow process. In addition, the insulation 51 prevents the molten solder from coming into contact with the exposed surface 25 of the fuse element 17. Further, in the fuse element 17, the low melting point metal exposed from the exposed surface 25 by the insulator 51 wets and spreads on the first and second electrodes 12 and 13 in a high temperature environment such as a reflow process, so that the connection solder Contact with 21 is prevented.

  Therefore, the fuse element 17 can prevent the low melting point metal from being attracted by the surface tension of the connecting solder 21 and the outer shape of the fuse element 17 is deformed by the outflow of the low melting point metal. Can be prevented from fluctuating in fusing characteristics such as not fusing, fusing time extending, or fusing less than a predetermined temperature or current value.

[Modification 2]
Further, in the protection element to which the present invention is applied, the exposed surface 25 of the fuse element 17 may be projected outside the first and second electrodes 12 and 13 as shown in FIG. The protective element 60 shown in FIG. 6 narrows the first and second electrodes 12 and 13 so as to be located on the inner side of both side edges of the insulating substrate 11, and the back surface of the insulating substrate 11 through the conductive through holes 61. 11b is connected to the first and second external connection electrodes 12a and 13a. The fuse element 17 has an exposed surface 25 directed to both sides in the energizing direction between the first and second electrodes 12 and 13, and the exposed surface 25 projects out of the first and second electrodes 12 and 13. As a result, a gap is formed between the exposed surface 25 and the first and second electrodes 12 and 13 and the connecting solder 21.

  Thereby, since the exposed surface 25 of the fuse element 17 is isolated from the conductors such as the first and second electrodes 12 and 13 and the connecting solder 21 by the insulator (gap), the fuse element 17 is subjected to a high temperature environment such as a reflow process. In this case, it is possible to prevent the low melting point metal exposed from the exposed surface 25 from spreading on the first and second electrodes 12 and 13 or being attracted by the surface tension of the connecting solder 21. Accordingly, the outer shape of the fuse element 17 is deformed due to the outflow of the low melting point metal, so that the fuse element 17 is not blown by a predetermined temperature or overcurrent, or the fusing time is extended. It is possible to prevent fluctuations in the fusing characteristics.

[Modification 3]
Further, as shown in FIG. 7, the protective element to which the present invention is applied has the exposed surface 25 of the fuse element 17 disposed between the first and second electrodes 12 and 13 and covers the refractory metal layer 24. The width of the covered surface 26 may be wider than the width of the support portion provided on the first and second electrodes 12 and 13. In the protection element 70 shown in FIG. 7, connection solder 21 is provided on the first and second electrodes 12 and 13, and a support portion 71 that supports the fuse element 17 is formed to protrude toward the inside of the insulating substrate 11. ing. Further, the protective element 70 has the covering surface 26 of the fuse element 17 on both sides in the energizing direction between the first and second electrodes 12 and 13.

  Further, in the protective element 70, an insulating layer 72 is formed on the heating element extraction electrode 16 on which the fuse element 17 is mounted. The insulating layer 72 can be formed using an insulating material having no wettability with respect to solder such as glass, solder resist, and insulating adhesive, and can be formed on the heating element extraction electrode 16 by printing or the like. The exposed surface 25 of the fuse element 17 is supported by the insulating layer 72.

  The fuse element 17 is formed so that the width of the covering surface 26 is wider than the width of the support portion 71 of the first and second electrodes 12 and 13, so that the exposed surface 25 continuous with both ends of the covering surface 26 is the first. The second electrode 12, 13 protrudes outside the support portion 71, and a gap is formed between the exposed surface 25, the first and second electrodes 12, 13 and the connection solder 21. Further, the fuse element 17 is isolated from the heating element extraction electrode 16 and the connecting solder 21 provided on the heating element extraction electrode 16 by the exposed surface 25 being supported by the insulating layer 72.

  Thus, the exposed surface 25 of the fuse element 17 is isolated from the conductors such as the first and second electrodes 12 and 13, the heating element lead-out electrode 16, and the connecting solder 21 by the insulator (gap and insulating layer 72). Therefore, in a high temperature environment such as a reflow process, the low melting point metal exposed from the exposed surface 25 wets and spreads on the first and second electrodes 12 and 13 and the heating element extraction electrode 16 or is melted. Suction by the surface tension of the solder 21 can be prevented. Accordingly, the outer shape of the fuse element 17 is deformed due to the outflow of the low melting point metal, so that the fuse element 17 is not blown by a predetermined temperature or overcurrent, or the fusing time is extended. It is possible to prevent fluctuations in the fusing characteristics.

  The protective element 70 preferably forms a shielding wall 73 on the first and second electrodes 12 and 13 for restricting the flow of the molten connecting solder 21. The shielding wall 73 can be formed using, for example, an insulating material having no wettability with respect to solder such as glass, solder resist, and insulating adhesive, and is formed on the first and second electrodes 12 and 13 by printing or the like. can do. By providing the shielding wall 73, it is possible to prevent the molten connecting solder 21 from spreading to the first and second external connecting electrodes 12a and 13a and coming into contact with the connecting solder with the external circuit board, thereby protecting the element 70. And the external circuit board can be connected.

  The protective element 70 includes the first and second electrodes 12 and 13 provided with support portions 71 having a width smaller than that of the covering surface 26, and the first and second electrodes 12 and 13 having a width smaller than that of the covering surface 26. It may be formed.

[Modification 4]
Further, as shown in FIG. 8, the protective element to which the present invention is applied is provided with a shielding wall that restricts the flow of the molten connecting solder 21 between the exposed surface 25 of the fuse element 17 and the connecting solder 21. It may be provided. In the protection element 80 shown in FIG. 8, the first and second electrodes 12 and 13 are provided with the connecting solder 21 and the shielding wall 81. The shielding wall 81 regulates the flow of the molten connecting solder 21 and can be formed using an insulating material having no wettability with respect to solder such as glass, solder resist, and insulating adhesive. It can be formed on the first and second electrodes 12 and 13 by printing or the like. The shielding wall 81 is formed along the extending direction of the exposed surface 25 of the fuse element 17 disposed on the first and second electrodes 12 and 13.

  The fuse element 17 has an exposed surface 25 directed to both sides in the energizing direction between the first and second electrodes 12 and 13, and the exposed surface 25 protrudes out of the connecting solder 21 and the shielding wall 81. A gap is formed between the exposed surface 25 and the first and second electrodes 12 and 13 and the connecting solder 21.

  As a result, the protection element 80 separates the exposed surface 25 of the fuse element 17 from the connecting solder 21 by the shielding wall 81. Therefore, the protective element 80 is configured such that the flow of the molten connection solder 21 is blocked by the shielding wall 81 in a high temperature environment such as a reflow process, and the low melting point metal exposed from the exposed surface 25 and the connection solder 21 , The low melting point metal can be prevented from being attracted by the surface tension of the connecting solder 21. Accordingly, the outer shape of the fuse element 17 is deformed due to the outflow of the low melting point metal, so that the fuse element 17 is not blown by a predetermined temperature or overcurrent, or the fusing time is extended. It is possible to prevent fluctuations in the fusing characteristics.

  In the protection element 80, the exposed surface 25 of the fuse element 17 is isolated from conductors such as the first and second electrodes 12 and 13 and the connecting solder 21 by an insulator (gap). Therefore, in the protective element 80, the low melting point metal exposed from the exposed surface 25 wets and spreads on the first and second electrodes 12 and 13 in a high temperature environment such as a reflow process, and the outer shape of the fuse element 17 is It is possible to prevent the fusing characteristics from fluctuating such as being deformed and not fusing depending on a predetermined temperature or overcurrent, or fusing time being extended, and conversely fusing less than a predetermined temperature or current value.

  As shown in FIG. 9, the protection element 80 may be provided with a regulating wall 82 at the tip of the exposed surface 25 of the fuse element, and the exposed surface 25 may be surrounded by the shielding wall 81 and the regulating wall 82. The regulation wall 82 can be similarly formed using the same material as the shielding wall 81.

  By surrounding the exposed surface 25 with the shielding wall 81 and the regulating wall 82, the protection element 80 regulates the flow of the molten low melting point metal and suppresses deformation of the fuse element 17 in a high temperature environment such as a reflow process. Can do. Further, in the protection element 80, by providing the regulation wall 82, the solder for connection provided on the connection electrode of the external circuit board has spread over the first and second electrodes 12, 13 via the castellation. Even in this case, it is possible to prevent the contact with the low melting point metal of the exposed surface 25 by damming with the regulation wall 82.

[Fuse element]
Next, a fuse element to which the present invention is applied will be described. In addition, in the following description, the same code | symbol is attached | subjected about the member similar to the protection element 10,50,60,70,80 mentioned above, and the detail is abbreviate | omitted. As shown in FIG. 10, the fuse element 90 to which the present invention is applied includes an insulating substrate 11, first and second electrodes 12 and 13 formed on both ends of the insulating substrate 11, both ends being first, A fuse element 17 connected to the second electrodes 12 and 13 and conducting between the first and second electrodes 12 and 13 is provided, and a cover member 18 for protecting the inside is mounted on the insulating substrate 11. .

  The fuse element 90 is connected to the fuse element 17 via the connection solder 21 provided on the first and second electrodes 12 and 13 in the same manner as the protection element 10 described above. The fuse element 17 can be easily connected between the first and second electrodes 12 and 13 by reflow soldering.

  Also in the fuse element 90, the fuse element 17 is arranged so that the low melting point metal layer 23 exposed outward from the exposed surface 25 does not touch the connecting solder 21. For example, as shown in FIG. 10, the fuse element 17 has exposed surfaces 25 on both sides in the energizing direction between the first and second electrodes 12 and 13, and on the first and second electrodes 12 and 13. A region other than the exposed surface 25 is connected by the connecting solder 21 provided on the surface. Thereby, in the fuse element 17, a gap is formed between the exposed surface 25 and the first and second electrodes 12 and 13, and the exposed surface 25 is connected to the connecting solder 21 and the first and second electrodes 12. , 13 is not touched.

  Thus, since the exposed surface 25 of the fuse element 17 is isolated from the conductors such as the first and second electrodes 12 and 13 and the connecting solder 21 by the insulator (gap), a high temperature environment such as a reflow process is performed. Below, the low melting point metal exposed from the exposed surface 25 is prevented from being attracted by the surface tension of the connecting solder 21 that spreads or melts on the first and second electrodes 12 and 13. Can do. Accordingly, the outer shape of the fuse element 17 is deformed due to the outflow of the low melting point metal, so that the fuse element 17 is not blown by a predetermined temperature or overcurrent, or the fusing time is extended. It is possible to prevent fluctuations in the fusing characteristics.

[Circuit configuration]
Such a fuse element 90 has a circuit configuration shown in FIG. The fuse element 90 is mounted on the external circuit via the first and second external connection electrodes 12a and 13a, and is incorporated in the current path of the external circuit. The fuse element 90 is not melted by self-heating while a predetermined rated current flows through the fuse element 17. The fuse element 90 cuts off the current path of the external circuit by disconnecting the first and second electrodes 12 and 13 by fusing the fuse element 17 by self-heating when an overcurrent exceeding the rating is applied. (FIG. 11B).

[Modification 5]
In the fuse element to which the present invention is applied, the exposed surface 25 of the fuse element 17 may be supported by a material that does not have wettability to the low melting point metal. In the fuse element 91 shown in FIG. 12, the exposed surface 25 is directed to both sides in the energization direction of the fuse element 17 between the first and second electrodes 12 and 13, and the exposed surface 25 of the fuse element 17 is insulated by an insulator 51. I support it.

  When the exposed surface 25 is supported by the insulator 51, the fuse element 17 is spread over the first and second electrodes 12 and 13 by melting the connecting solder 21 in a high temperature environment such as a reflow process. In addition, the insulation 51 prevents the molten solder from coming into contact with the exposed surface 25 of the fuse element 17. Further, the fuse element 17 has a low melting point metal exposed from the exposed surface 25 wetted and spread on the first and second electrodes 12 and 13 in a high temperature environment such as a reflow process, Contact is prevented.

  Therefore, the fuse element 17 can prevent the low melting point metal from being attracted by the surface tension of the connecting solder 21, the outer shape is deformed by the outflow of the low melting point metal, and is blown out at a predetermined temperature or overcurrent. It is possible to prevent fusing characteristics from fluctuating such that the fusing time is extended or the fusing time is extended, and conversely, fusing is performed at less than a predetermined temperature or current value.

[Modification 6]
In the fuse element to which the present invention is applied, the exposed surface 25 of the fuse element 17 may be projected outside the first and second electrodes 12 and 13. The fuse element 92 shown in FIG. 13 narrows the first and second electrodes 12 and 13 so as to be located on the inner side of both side edges of the insulating substrate 11, and the back surface of the insulating substrate 11 through the conductive through hole 61. 11b is connected to the first and second external connection electrodes 12a and 13a. The fuse element 17 has an exposed surface 25 directed to both sides in the energizing direction between the first and second electrodes 12 and 13, and the exposed surface 25 projects out of the first and second electrodes 12 and 13. As a result, a gap is formed between the exposed surface 25 and the first and second electrodes 12 and 13 and the connecting solder 21.

  Thereby, since the exposed surface 25 of the fuse element 17 is isolated from the conductors such as the first and second electrodes 12 and 13 and the connecting solder 21 by the insulator (gap), the fuse element 17 is subjected to a high temperature environment such as a reflow process. In this case, it is possible to prevent the low melting point metal exposed from the exposed surface 25 from being attracted by the surface tension of the connecting solder 21 that has spread or melted on the first and second electrodes 12 and 13. it can. Accordingly, the outer shape of the fuse element 17 is deformed due to the outflow of the low melting point metal, so that the fuse element 17 is not blown by a predetermined temperature or overcurrent, or the fusing time is extended. It is possible to prevent fluctuations in the fusing characteristics.

[Modification 7]
In the fuse element to which the present invention is applied, the exposed surface 25 of the fuse element 17 is disposed between the first and second electrodes 12 and 13 and the refractory metal layer 24 is covered as shown in FIG. The width of the covered surface 26 may be wider than the width of the support portion of the first and second electrodes 12 and 13. In the fuse element 93 shown in FIG. 14, connection solder 21 is provided on the first and second electrodes 12 and 13, and a support portion 71 that supports the fuse element 17 is formed to protrude toward the inside of the insulating substrate 11. ing. Further, the protective element 70 has the covering surface 26 of the fuse element 17 on both sides in the energizing direction between the first and second electrodes 12 and 13.

  The fuse element 17 is formed such that the width of the covering surface 26 is wider than the width of the first and second electrodes 12, 13, so that the exposed surfaces 25 that are continuous with both ends of the covering surface 26 are first and second. The electrode 12, 13 protrudes outside the support portion 71, and a gap is formed between the exposed surface 25 and the first and second electrodes 12, 13 and the connecting solder 21.

  Thereby, the exposed surface 25 of the fuse element 17 is isolated from the conductors such as the first and second electrodes 12 and 13 and the connecting solder 21 by the insulator (gap). In this case, it is possible to prevent the low melting point metal exposed from the exposed surface 25 from being attracted by the surface tension of the connecting solder 21 that has spread or melted on the first and second electrodes 12 and 13. it can. Accordingly, the outer shape of the fuse element 17 is deformed due to the outflow of the low melting point metal, so that the fuse element 17 is not blown by a predetermined temperature or overcurrent, or the fusing time is extended. It is possible to prevent fluctuations in the fusing characteristics.

  In addition, it is preferable that the fuse element 93 forms a regulation wall 73 that regulates the flow of the molten connecting solder 21 on the first and second electrodes 12 and 13. In addition, the fuse element 93 is provided with the first and second electrodes 12 and 13 having a narrower width than the covering surface 26 and the first and second electrodes 12 and 13 having a width smaller than the covering surface 26. It may be formed.

[Modification 8]
Further, as shown in FIG. 15, the fuse element to which the present invention is applied has a shielding wall for restricting the flow of the molten connecting solder 21 between the exposed surface 25 of the fuse element 17 and the connecting solder 21. It may be provided. In the fuse element 94 shown in FIG. 15, the first and second electrodes 12 and 13 are provided with the connecting solder 21 and the shielding wall 81.

  The fuse element 17 has an exposed surface 25 directed to both sides in the energizing direction between the first and second electrodes 12 and 13, and the exposed surface 25 protrudes out of the connecting solder 21 and the shielding wall 81. A gap is formed between the exposed surface 25 and the first and second electrodes 12 and 13 and the connecting solder 21.

  As a result, the fuse element 94 separates the exposed surface 25 of the fuse element 17 from the connecting solder 21 by the shielding wall 81. Therefore, in the fuse element 94, in a high temperature environment such as a reflow process, the flow of the molten connecting solder 21 is blocked by the shielding wall 81, and the low melting point metal exposed from the exposed surface 25 and the connecting solder 21 , The low melting point metal can be prevented from being sucked by the molten surface tension of the connecting solder 21. Accordingly, the outer shape of the fuse element 17 is deformed due to the outflow of the low melting point metal, so that the fuse element 17 is not blown by a predetermined temperature or overcurrent, or the fusing time is extended. It is possible to prevent fluctuations in the fusing characteristics.

  In the fuse element 94, the exposed surface 25 of the fuse element 17 is isolated from conductors such as the first and second electrodes 12 and 13 and the connecting solder 21 by an insulator (gap). Therefore, in the fuse element 94, the low melting point metal exposed from the exposed surface 25 wets and spreads on the first and second electrodes 12 and 13 in a high temperature environment such as a reflow process, and the outer shape of the fuse element 17 is increased. It is possible to prevent the fusing characteristics from fluctuating such as being deformed and not fusing depending on a predetermined temperature or overcurrent, or fusing time being extended, and conversely fusing less than a predetermined temperature or current value.

  As shown in FIG. 16, the fuse element 94 may be provided with a regulating wall 82 at the tip of the exposed surface 25 of the fuse element, and the exposed surface 25 may be surrounded by the shielding wall 81 and the regulating wall 82. The regulation wall 82 can be similarly formed using the same material as the shielding wall 81. By surrounding the exposed surface 25 with the shielding wall 81 and the regulating wall 82, the fuse element 94 regulates the flow of the molten low melting point metal and suppresses deformation of the fuse element 17 in a high temperature environment such as a reflow process. Can do. Further, in the fuse element 94, by providing the regulation wall 82, the solder for connection provided on the connection electrode of the external circuit board has spread over the first and second electrodes 12, 13 via the castellation. Even in this case, it is possible to prevent the contact with the low melting point metal of the exposed surface 25 by damming with the regulation wall 82.

DESCRIPTION OF SYMBOLS 10 Protection element, 11 Insulating substrate, 12 1st electrode, 13 2nd electrode, 14 Heating body, 15 Insulating layer, 16 Heating body extraction electrode, 17 Fuse element, 18 Cover member, 19 Heating body electrode, 21 For connection Solder, 22 flux, 23 low melting point metal layer, 24 high melting point metal layer, 25 exposed surface, 26 coated surface, 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 Protection element, 51 Insulator, 60 Protection element, 61 Conductive through hole, 70 Protection element, 71 Support part, 72 Insulation layer, 80 Protection Element, 81 shielding wall, 82 regulating wall, 90-94 fuse element

Claims (8)

An insulating substrate;
A heating element;
A first electrode and a second electrode formed on the insulating substrate;
A fuse element having both ends connected to the first electrode and the second electrode via a connecting material;
A protection element comprising a regulation wall for regulating wetting and spreading of the solder for connection with a circuit board to the fuse element. The first electrode and the second electrode are formed on a surface of the insulating substrate,
The first electrode is provided on the back surface of the insulating substrate and is connected to a first external connection electrode connected to the circuit board via the connection solder,
The second electrode is provided on the back surface of the insulating substrate and is connected to a second external connection electrode connected to the circuit board via the connection solder,
The protection element according to claim 1, wherein the restriction wall is provided on the first electrode and the second electrode.   The protection element according to claim 1, wherein the restriction wall is made of an insulating material that does not have wettability to the connection solder. The fuse element has a low melting point metal layer covered with a high melting point metal layer, and a pair of end faces are exposed surfaces from which the low melting point metal layer is exposed,
Between the exposed surface of the fuse element and the connection material, a shielding wall that regulates the flow of the molten connection material is provided,
The protection element according to claim 1, wherein the exposed surface of the fuse element is surrounded by the restriction wall and the shielding wall. An insulating substrate;
A first electrode and a second electrode formed on the insulating substrate;
A fuse element having both ends connected to the first electrode and the second electrode via a connecting material;
A fuse element comprising: a regulation wall that regulates wetting and spreading of the solder for connection to the circuit board to the fuse element. The first electrode and the second electrode are formed on a surface of the insulating substrate,
The first electrode is provided on the back surface of the insulating substrate and is connected to a first external connection electrode connected to the circuit board via the connection solder,
The second electrode is provided on the back surface of the insulating substrate and is connected to a second external connection electrode connected to the circuit board via the connection solder,
The fuse element according to claim 5, wherein the restriction wall is provided on the first electrode and the second electrode.   The fuse element according to claim 5 or 6, wherein the restriction wall is made of an insulating material having no wettability with respect to the connection solder. The fuse element has a low melting point metal layer covered with a high melting point metal layer, and a pair of end faces are exposed surfaces from which the low melting point metal layer is exposed,
Between the exposed surface of the fuse element and the connection material, a shielding wall that regulates the flow of the molten connection material is provided,
The fuse element according to any one of claims 5 to 7, wherein the exposed surface of the fuse element is surrounded by the restriction wall and the shielding wall.

Images