JP6437253B2 - Protective element and mounting body - Google Patents

Description

  The present invention relates to a protection element that is mounted on a current path and cuts off the current path by fusing a fusible conductor as the heating element generates heat, and a mounting body in which the protection element is mounted on a circuit board.

  Many secondary batteries that can be charged and used repeatedly are processed into battery packs and provided to users. Particularly in lithium ion secondary batteries with high weight energy density, in order to ensure the safety of users and electronic devices, in general, a battery pack incorporates a number of protection circuits such as overcharge protection and overdischarge protection, It has a function of shutting off the output of the battery pack in a predetermined case.

  In this type of protection circuit, an overcharge protection or an overdischarge protection operation of the battery pack is performed by turning on / off the output using an FET switch built in the battery pack. However, when the FET switch is short-circuited for some reason, when a lightning surge is applied and an instantaneous large current flows, the output voltage drops abnormally due to the life of the battery cell, or conversely an excessive abnormal current Even when a battery pack is output, battery packs and electronic devices must be protected from accidents such as fire. Therefore, in order to safely shut off the output of the battery cell in any possible abnormal state, a protection element composed of a protection element having a function of cutting off the current path by an external signal is used.

  As a protection element of such a protection circuit for a lithium ion secondary battery or the like, as described in Patent Document 1, the protection element has a heating element, and the heating element causes a soluble conductor on the current path. In general, a structure for fusing is used.

  As a related technique of the present invention, a protection element 100 is shown in FIGS. The protective element 100 includes an insulating substrate 101, a heating element 103 laminated on the insulating substrate 101 and covered with an insulating member 102 such as glass, a pair of electrodes 104 a and 104 b formed on both ends of the insulating substrate 101, A heating element extraction electrode 105 laminated on the member 101 so as to overlap with the heating element 103, and a fusible conductor having both ends connected to the pair of electrodes 104a and 104b and the central portion connected to the heating element extraction electrode 105, respectively. 106.

  One end of the heating element extraction electrode 105 is connected to the first heating element electrode 107. The other end of the heating element 103 is connected to the second heating element electrode 108. The protective element 100 is coated with a flux 111 on almost the entire surface of the soluble conductor 106 in order to prevent oxidation of the soluble conductor 106. In addition, the protection element 100 may place a cover member on the insulating substrate 101 in order to protect the inside.

  In such a protection element 100, a pair of electrodes 104 a and 104 b formed on the surface of the insulating substrate 101 are formed on the back surface of the insulating substrate 101 through conductive through holes 109 formed on the side surfaces of the insulating substrate 101. It is electrically connected to the external connection electrode 110. And the protection element 100 comprises a part of current path of the said protection circuit by connecting the external connection electrode 110 on the board | substrate of the protection circuit for lithium ion secondary batteries etc. FIG.

JP 2010-003665 A

  By the way, in recent years, HEV (Hybrid Electric Vehicle) and EV (Electric Vehicle) using a battery and a motor are rapidly spreading. As a power source for HEV and EV, a lithium ion secondary battery has been used from the viewpoint of energy density and output characteristics. Lithium ion secondary batteries have also been put into practical use in electric tools, electric assist bicycles, aircraft, and the like. This type of application requires high voltage and large current. For this reason, dedicated cells that can withstand high voltages and large currents have been developed, but in many cases due to manufacturing cost problems, it is necessary to use general-purpose cells by connecting multiple battery cells in series and in parallel. Secures sufficient voltage and current.

  In such a large current application as a lithium ion secondary battery, further improvement of the current rating is required also in the protective element. That is, when a lithium-ion secondary battery or the like increases in voltage and current, but the protective element mounted on the protection circuit does not have a rating corresponding to the increase in voltage and current, normal use There is a risk that a soluble conductor on the current path may be blown in a state, and a heat generation of the protective element may cause a bad connection or a peripheral element.

  Also in the protective element 100, the conduction resistance between the pair of electrodes 104a and 104b connected by the fusible conductor can be sufficiently lowered (for example, less than 1 mΩ) to meet the current rating improvement.

  However, in the protective element 100 in which the external connection electrode 110 is provided on the back surface of the insulating substrate 101 and the pair of electrodes 104a and 104b are connected to the external connection electrode 110 by the conductive through hole 109, the pair of electrodes 104a and 104b are respectively provided. The conduction resistance between the external connection electrode 110 and the external connection electrode 110 is high, for example, 0.5 to 1.0 mΩ or more with only the through hole 109 on one side, and even if the conductive through hole is filled with a conductor, the conduction resistance on the insulating substrate side There is a limit to lowering.

  In addition, for example, in safety standards such as UL, the temperature rise of the device surface and the terminal is defined as an index for defining the rated current of the fuse, and the temperature of the terminal and the device surface rises when the through hole is heated by energization. Therefore, the current rating must be set so as to satisfy the safety standard including the amount of heat generated in the through hole, and this has been a factor that hinders the high rating.

  Further, along with downsizing of electronic equipment and higher current rating, a protective element having a small size and a high current rating has been demanded.

  Accordingly, the present invention provides a small protection element and circuit capable of improving the current rating in response to higher voltage and higher current of a lithium ion secondary battery and the like, and downsizing and higher rating of electronic equipment. An object is to provide a mounting body in which a protective element is mounted on a substrate.

In order to solve the above-described problems, a protection element according to the present invention includes an insulating substrate, a heating element disposed on the insulating substrate, a heating element extraction electrode electrically connected to the heating element, and the insulation. By fitting to the substrate, it is arranged on the surface of the insulating substrate and melted by heat, and both ends are provided along the side surface of the insulating substrate, and are directed to the back side, and connected to an external circuit. and a pair of terminal portion, in which and a fusible conductor to cut off the current path of the external circuit by between the pair of terminal portions is blown.
The protection element according to the present invention includes an insulating substrate, a heating element disposed on the insulating substrate, a heating element extraction electrode electrically connected to the heating element, and a pair of terminals connected to an external circuit. A fusible conductor that cuts off the current path of the external circuit by fusing between the pair of terminal parts, and the fusible conductor is disposed on the surface of the insulating substrate and melted by heat. And a pair of terminal portions provided at both ends of the fusing portion and projecting from the fusing portion to the surface side of the insulating substrate, formed on the surface of the insulating substrate, and the heating element. A heating element electrode connected to the open end of the substrate and an external connection terminal protruding to the surface side of the insulating substrate by being connected to the heating element electrode.

The mounting body according to the present invention is a mounting body in which a protective element is mounted on a circuit board, wherein the protective element includes an insulating substrate, a heating element disposed on the insulating substrate, and the heating element electrically. By being connected to the connected heating element extraction electrode and the insulating substrate, the melted portion is disposed on the surface of the insulating substrate and melted by heat, and provided at both ends along the side surface of the insulating substrate. And a fusible conductor that has a pair of terminal portions connected to an external circuit and that cuts off the current path of the external circuit by fusing between the pair of terminal portions. .
The mounting body according to the present invention is a mounting body in which a protective element is mounted on a circuit board, wherein the protective element includes an insulating substrate, a heating element disposed on the insulating substrate, and the heating element electrically. A heating element lead electrode connected, and a pair of terminal portions connected to an external circuit, and a fusible conductor that cuts off a current path of the external circuit by fusing between the pair of terminal portions, The fusible conductor is disposed on the surface of the insulating substrate and is provided at both ends of the fusing portion that is melted by heat and the fusing portion, and the pair of terminals protruding from the fusing portion to the surface side of the insulating substrate. A heating element electrode formed on the surface of the insulating substrate and connected to the open end of the heating element, and protruded to the surface side of the insulating substrate by being connected to the heating element electrode. And an external connection terminal.

  According to the present invention, a through-hole is provided in the insulating substrate, and the conductive path of the fusible conductor is not drawn out to the external circuit, but a terminal portion serving as a connection terminal with the external circuit is formed in the fusible conductor. The conduction resistance between the external circuit and the fusible conductor is determined by the resistance value of the fusible conductor itself, and is not affected by the configuration on the insulating substrate side. Therefore, according to the present invention, it is possible to reduce the resistance of the energization path of the entire element and easily improve the current rating.

1A is an external perspective view showing the upper surface side of the protective element, and FIG. 1B is an external perspective view showing the bottom surface side of the protective element. FIG. 2A is a plan view in which the cover member of the protective element is omitted, and FIG. 2B is a cross-sectional view taken along the line A-A ′ of the protective element shown in FIG. FIG. 3A is a plan view showing the protective element after melting the fusible conductor with the cover member omitted, and FIG. 3B is a cross-sectional view taken along the line AA ′ of the protective element shown in FIG. . 4A and 4B are perspective views showing a manufacturing process of the protective element, where FIG. 4A is an insulating substrate, FIG. 4B is a state where a soluble conductor is fitted to the insulating substrate, and FIG. The provided state, (D) shows the state where the cover member is provided. FIG. 5 is a diagram illustrating a circuit configuration example of the battery pack to which the protection element is connected. 6A and 6B are diagrams showing a circuit configuration of the protection element, in which FIG. 6A shows before the fusible conductor is blown, and FIG. 6B shows after the fusible conductor is blown. FIG. 7 is a plan view showing a modification of the protection element to which the present invention is applied. FIG. 8A is a plan view showing a protective element including a fusible conductor provided with a plurality of fusing parts, with the cover member omitted, and FIG. 8B shows the protective element shown in FIG. It is AA 'sectional drawing. FIG. 9 is a plan view for explaining a manufacturing process of a fusible conductor having a plurality of fusing parts, where (A) is one in which both sides of the fusing part are integrally supported by terminal parts, and (B) is a fusing part. The one side of this is supported integrally by the terminal portion. FIG. 10 is a perspective view showing a manufacturing process of a protection element including a soluble conductor provided with a plurality of fusing parts, (A) is an insulating substrate, and (B) is an insulating substrate fitted with the soluble conductor. (C) shows a state in which a flux is provided on a soluble conductor, and (D) shows a state in which a cover member is provided. FIG. 11A is a plan view showing a protective element having a plurality of fusible conductors with the cover member omitted, and FIG. 11B is a cross-sectional view taken along the line AA ′ of the protective element shown in FIG. It is. FIG. 12A is an external perspective view showing the upper surface side of the protection element in which the terminal portion protrudes from the surface side of the insulating substrate, and FIG. 12B is an external perspective view showing the bottom surface side of the protection element. FIG. 13A is a plan view showing a protective element having a fusible conductor provided with a plurality of fusing parts and having a terminal part projecting to the surface side of the insulating substrate, with the cover member omitted, and FIG. FIG. 13B is a cross-sectional view taken along line AA ′ of the protection element shown in FIG. FIG. 14 is a perspective view showing a manufacturing process of a protection element including a fusible conductor provided with a plurality of fusing parts and having a terminal part projecting to the surface side of the insulating substrate, (A) is an insulating substrate, B shows a state in which a soluble conductor and external connection terminals are connected to an insulating substrate, (C) shows a state in which a flux is provided on the soluble conductor, and (D) shows a state in which a cover member is provided. FIG. 15 is a cross-sectional view showing a protection element in which a heating element is provided on the back side of the insulating substrate. FIG. 15A shows the protection element in which the terminal portion protrudes on the back side of the insulating substrate, and FIG. The protection element which protruded to the surface side of the insulated substrate is shown. FIG. 16 is a cross-sectional view showing a protective element in which a heating element is provided inside the insulating substrate, (A) shows the protective element with the terminal portion protruding to the back side of the insulating substrate, and (B) shows the terminal portion. The protection element protruded to the surface side of the insulating substrate is shown. FIG. 17 is a diagram showing a protection element in which a heating element and a soluble conductor are adjacent to each other on the surface of an insulating substrate, (A) is a plan view with the cover member omitted, and (B) is shown in (A). It is AA 'sectional drawing of a protection element. FIG. 18 is a perspective view showing a soluble conductor having a high-melting point metal layer and a low-melting point metal layer and having a covering structure, and (A) is a structure in which the low-melting point metal layer is an inner layer and is covered with a high-melting point metal layer. (B) shows a structure in which a high melting point metal layer is used as an inner layer and is covered with a low melting point metal layer. FIG. 19 is a perspective view showing a soluble conductor having a laminated structure of a high melting point metal layer and a low melting point metal layer, wherein (A) shows an upper and lower two layer structure, and (B) shows a three layer structure of an inner layer and an outer layer. . FIG. 20 is a cross-sectional view showing a soluble conductor having a multilayer structure of a high melting point metal layer and a low melting point metal layer. FIG. 21 is a plan view showing a fusible conductor in which a linear opening is formed in the refractory metal layer and the low melting point metal layer is exposed. FIG. 21A shows an opening formed along the longitudinal direction. (B) is one in which an opening is formed along the width direction. FIG. 22 is a plan view showing a soluble conductor in which a circular opening is formed in the high melting point metal layer and the low melting point metal layer is exposed. FIG. 23 is a plan view showing a soluble conductor in which a circular opening is formed in a refractory metal layer and a low melting metal is filled therein. FIG. 24 is a perspective view showing a soluble conductor from which a low melting point metal surrounded by a high melting point metal is exposed. FIG. 25 is a diagram showing a protection element to which the fusible conductor shown in FIG. 24 is connected, (A) is a plan view showing the cover member omitted, and (B) is an A- of the protection element shown in (A). It is A 'sectional drawing. 26A and 26B are views showing a conventional protection element with a cover member omitted, in which FIG. 26A is a plan view and FIG. 26B is a cross-sectional view taken along line A-A ′ of FIG.

  Hereinafter, a protection element and a mounting body 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]
1 and 2 show a protective element 1 to which the present invention is applied. 1A is an external perspective view showing the upper surface side of the protection element 1, and FIG. 1B is an external perspective view showing the bottom surface side of the protection element 1. FIG. FIG. 2A is a plan view in which the cover member of the protection element 1 is omitted, and FIG. 2B is a cross-sectional view taken along the line AA ′ shown in FIG. FIG. 3 is a plan view in which the cover member of the protective element 1 is omitted after the fusible conductor is melted, and FIG. 3B is a cross-sectional view taken along line AA ′ shown in FIG. The protection element 1 is laminated on the insulating substrate 10, the surface 10 a of the insulating substrate 10 and covered with the insulating member 12, and the heating element laminated on the insulating member 12 so as to overlap the heating member 11. The insulating substrate 10 provided with the soluble conductor 15 and the soluble conductor 15 which is fitted to the extraction electrode 13 and a pair of opposite side edges of the insulating substrate 10 and whose central portion is connected to the heating element extraction electrode 13. And a cover member 19 covering the surface 10a.

  The protection element 1 realizes a protection element having a small size and a high current rating. For example, although the length of one side is about 3 to 6 mm as a dimension of the insulating substrate 10, the resistance value of the entire element is small. 0.5-1mΩ, 30-60A rating and higher rating are achieved. Of course, the present invention can be applied to protective elements having all sizes, resistance values, and current ratings.

  The insulating substrate 10 is formed, for example, in a square shape, and is formed of an insulating member such as alumina, glass ceramics, mullite, zirconia. In addition, although the material used for printed wiring boards, such as a glass epoxy board | substrate and a phenol board | substrate, may be used, it is necessary to pay attention to the temperature at the time of fusing of the soluble conductor 15.

  The heating element 11 is a conductive member that generates heat when energized, and is made of, for example, nichrome, W, Mo, Ru, or a material containing these. The heating element 11 is obtained by mixing a powdery body of these alloys, compositions, or compounds with a resin binder or the like and forming a paste on the insulating member 12 laminated on the insulating substrate 10 using a screen printing technique. It can be formed by patterning and firing.

  The heating element 11 is covered with an insulating member 12 and is opposed to the heating element extraction electrode 13 and the fusible conductor 15 connected to the heating element extraction electrode 13 via the insulating member 12. The insulating member 12 is provided to protect and insulate the heating element 11 and to efficiently transmit the heat of the heating element 11 to the soluble conductor 15, and is made of, for example, a glass layer. The protective element 1 is formed on the insulating member 12 in which the heating element 11 is laminated on the surface 10a of the insulating substrate 10 and is covered with the insulating member 12, thereby efficiently transferring the heat of the heating element 11 to a soluble conductor. 15 can tell. In the protection element 1, the heating element 11 may be laminated on the surface 10 a of the insulating substrate 10, and the surface of the heating element 11 may be covered with the insulating member 12.

  The heating element 11 has one end connected to the heating element extraction electrode 13 and the other end connected to the heating element electrode 16. The heating element lead-out electrode 13 is formed on the surface 10a of the insulating substrate 10 and is laminated on the insulating member 12 so as to face the heating element 11 and the lower layer portion 13a connected to the heating element 11, and is a soluble conductor. 15 and an upper layer portion 13b connected to the upper layer portion 13b. Thus, the heating element 11 is electrically connected to the soluble conductor 15 via the heating element extraction electrode 13. Note that the heating element extraction electrode 13 is disposed to face the heating element 11 with the insulating member 12 interposed therebetween, whereby the soluble conductor 15 can be melted and the molten conductor can be easily aggregated.

  The heating element electrode 16 is formed on the surface 10a of the insulating substrate 10 and is continuous with the external connection terminal 18 formed on the back surface 10b of the insulating substrate 10 through the through hole 17 in which the conductive layer is formed. .

  The heating element extraction electrode 13 and the heating element electrode 16 are formed of a conductive pattern such as Ag or Cu, and have Ni / Au plating, Ni / Pd plating, Ni / Pd / Au plating, etc. on the surface as appropriate as an anti-oxidation measure. The protective film is formed.

  In the protective element 1, an energization path to the heating element 11 reaching the heating element electrode 16, the heating element 11, the heating element extraction electrode 13, and the soluble conductor 15 is formed. The protection element 1 is connected to an external circuit in which the heating element electrode 16 energizes the heating element 11 via the external connection terminal 18, and energization between the heating element electrode 16 and the soluble conductor 15 is controlled by the external circuit. The

  In addition, the protection element 1 constitutes a part of the energization path to the heating element 11 by connecting the soluble conductor 15 to the heating element extraction electrode 13. Therefore, when the fusible conductor 15 is melted and the connection with the external circuit is interrupted, the protective element 1 can also stop the heat generation because the energization path to the heating element 11 is also interrupted.

[Soluble conductor]
The fusible conductor 15 which is fitted to a pair of opposing side edges of the insulating substrate 10 and whose central part is connected to the heating element extraction electrode 13 has a pair of terminal parts 20 connected to an external circuit. As shown in FIG. 3, the central portion connected to the heating element extraction electrode 13 is melted, and the current path of the external circuit is blocked by melting between the heating element extraction electrode 13 and the terminal portion 20. is there.

  The fusible conductor 15 is formed in a plate shape, and terminal portions 20 connected to an external circuit are provided at both ends. The fusible conductor 15 constitutes a part of the current path of the circuit board by connecting the terminal part 20 to the land part of the circuit board on which the protection element 1 is mounted, and the current path is formed by fusing. Cut off.

  The fusible conductor 15 is electrically and mechanically connected to the heating element lead-out electrode 13 at the center by a bonding material such as a connecting solder. Further, both ends of the fusible conductor 15 are bent along the side surface of the insulating substrate 10, so that the fusible conductor 15 is fitted to the insulating substrate 10, and the terminal portion 20 is directed to the back surface 10 b side of the insulating substrate 10. As a result, the protection element 1 has the back surface 10b of the insulating substrate 10 as a mounting surface on an external circuit board, and is connected to the heating element electrode 16 through the pair of terminal portions 20 and the through holes 17 of the fusible conductor 15. The external connection terminal 18 is incorporated into an external circuit by being connected to a land portion of the circuit board.

  Since the protective element 1 is provided with the terminal portion 20 that is a connection terminal with an external circuit on the fusible conductor 15, the current rating can be improved. That is, as described above, in the configuration in which the through-hole connecting the front electrode, the back electrode, and the front and back electrodes that lead the conductive path of the soluble conductor to the external circuit is provided on the insulating substrate, the hole diameter or hole of the through hole or castellation Due to the limitation of the number, the resistivity of the conductive paste, and the limitation of the film thickness, it is difficult to realize the resistance value of the soluble conductor or less, and it is difficult to increase the current rating. Further, if the area is increased in order to reduce the resistance of the conductive path of the fusible conductor provided on the insulating substrate, the entire protective element is increased in size.

  On the other hand, the protective element 1 does not provide a through hole or the like in the insulating substrate 10 to draw out the energization path of the fusible conductor 15 to the external circuit, but the fusible conductor 15 has a terminal portion 20 serving as a connection terminal to the external circuit. Therefore, the conduction resistance between the external circuit and the fusible conductor 15 is determined by the resistance value of the fusible conductor 15 itself, and does not depend on the configuration on the insulating substrate 10 side. Therefore, according to the protective element 1, it is possible to reduce the resistance of the energization path of the entire element and easily improve the current rating. Further, according to the protection element 1, it is not necessary to provide a current-carrying path for the soluble conductor 15 in the insulating substrate 10, and the entire element can be reduced in size.

  The soluble conductor 15 provided with the terminal portion 20 can be manufactured, for example, by bending both end portions of the plate-like soluble conductor 15. Note that, since the fusible conductor 15 and the external circuit are connected to the protection element 1 via the terminal portion 20, it is not necessary to provide a separate electrode for connection to the external circuit on the insulating substrate 10.

[Mating recess]
In addition, the insulating substrate 10 has a fitting recess 21 formed in a pair of side edge portions to which the terminal portion 20 of the fusible conductor 15 is fitted. By providing the fitting recess 21 in the insulating substrate 10, the protective element 1 does not increase the mounting area on the circuit board and can fix the fitting position of the soluble conductor 15. Furthermore, by providing the fitting recess 21, the insulating substrate 10 can be made compatible with a multi-sided substrate in the manufacturing process of the protection element 1, which can contribute to improvement of productivity and reduction of processing costs.

[Layer structure of soluble conductor]
Here, the protective element 1 is incorporated on the current path of the external circuit, and while improving the current rating, the fusible conductor 15 is quickly melted by the heat generated by the heating element 11 in an emergency, etc. It is necessary to interrupt the current path of the external circuit. Therefore, the fusible conductor 15 may contain a low-melting-point metal layer and a high-melting-point metal layer in order to improve both the current rating by reducing resistance and shortening the fusing time due to heat generation of the heating element 11. preferable.

  The refractory metal is Ag, Cu, or an alloy containing these as a main component, and preferably has a high melting point that does not melt even when board mounting is performed in a reflow furnace. As the low melting point metal, it is preferable to use solder or Pb-free solder containing Sn as a main component. The melting point of the low melting point metal is not necessarily higher than the temperature of the reflow furnace, and may be melted at about 200 ° C.

  By containing the high melting point metal and the low melting point metal, when the protective element 1 is mounted on the circuit board by reflow mounting or the like, the mounting temperature exceeds the melting temperature of the low melting point metal and the low melting point metal is melted. However, the high melting point metal can suppress the outflow of the low melting point metal to the outside, the shape of the soluble conductor 15 can be maintained, and fluctuations in current rating and fusing time can be prevented. Further, at the time of melting, the low melting point metal melts, and the high melting point metal is eroded (soldered), so that it can be rapidly melted at a temperature lower than the melting point of the high melting point metal. Note that the soluble conductor 15 can be formed in various configurations, as will be described later.

  Further, the fusible conductor 15 is formed by laminating a high melting point metal layer on a low melting point metal layer serving as an inner layer, so that the electric resistivity is half that of a conventional fusible conductor using lead-based high melting point solder. As a result, the current rating can be increased.

  Further, the fusible conductor 15 has a structure in which a low melting point metal is covered with a high melting point metal, so that even when the terminal portion 20 is provided and connected to the circuit board via the mounting solder, the melting conductor 15 is melted by the mounting solder. Can be suppressed. For example, when a soluble conductor such as lead is mounted via a lead-free solder, the soluble conductor is easily melted at a reflow temperature of about 250 ° C. by tin constituting the lead-free solder, and the soluble conductor is melted. End up. In this respect, the fusible conductor 15 is coated with a high melting point metal with a low melting point metal. Therefore, even when exposed to a reflow temperature, melting by the mounting solder is suppressed, and melting and deformation can be prevented. it can.

  Furthermore, the fusible conductor 15 can improve the resistance (pulse resistance) to a surge in which an abnormally high voltage is instantaneously applied to the electrical system in which the protection element 1 is incorporated. That is, the fusible conductor 15 must not be blown until, for example, a current of 100 A flows for several milliseconds. In this respect, since a large current flowing in a very short time flows in the surface layer of the conductor (skin effect), the fusible conductor 15 is caused by a surge by providing a refractory metal layer such as Ag plating having a low resistance value as the outer layer. It is easy to flow the applied current and can prevent fusing due to self-heating. Therefore, the fusible conductor 15 can greatly improve the resistance to surge as compared with a fuse made of a conventional solder alloy.

[Heat radiation electrode]
In the protection element 1, the first heat radiation electrode 23 is formed on the surface 10 a of the insulating substrate 10. The first heat dissipating electrode 23 is formed in the vicinity of the pair of side edges of the insulating substrate 10 to which the soluble conductor 15 is fitted, and is connected to the soluble conductor 15, whereby the soluble conductor 15 in the vicinity of the terminal portion 20. It absorbs the heat efficiently. The first heat radiation electrode 23 can be formed using an electrode material such as Ag or Cu, for example, and is connected to the soluble conductor 15 via a connection material such as connection solder.

  By providing the first heat dissipation electrode 23, the protection element 1 dissipates heat in the vicinity of the terminal portion 20 of the soluble conductor 15 toward the insulating substrate 10, and the heat generating area of the soluble conductor 15 is heated to the heating element extraction electrode 13. Concentrate on the central part connected with. Thereby, as for the meltable conductor 15, a melt | fusion part is limited to a center part and can interrupt | block a current path rapidly. Also, the fusible conductor 15 can prevent explosive fusing and scattering of the molten conductor by limiting the heat generating part even when arc discharge is involved when the self-heating is interrupted due to overcurrent. In addition, the insulation properties are not impaired.

  In this case, the insulating substrate 10 is used to dissipate the heat of the fusible conductor 15, and a ceramic substrate having good thermal conductivity is preferably used. Moreover, as an adhesive agent which connects the soluble conductor 15 to the 1st thermal radiation electrode 23, what is excellent in thermal conductivity is preferable regardless of electroconductivity.

  The first heat dissipation electrode 23 is connected to the second heat dissipation electrode 25 provided on the back surface 10 b of the insulating substrate 10 through the through hole 24. The through hole 24 has a heat conductive layer formed of a conductive material having excellent heat conductivity. Further, the second heat radiation electrode 25 can be formed of the same material as that of the first heat radiation electrode 23. By providing the through-hole 24 and the second heat-dissipating electrode 25 that are continuous with the first heat-dissipating electrode 23, the protection element 1 can dissipate the heat of the soluble conductor 15 more efficiently. The second heat dissipating electrode 25 does not constitute a current path of the external circuit and does not need to be connected to the external circuit. However, the second heat dissipating electrode 25 is not required to be connected to the external circuit. You may connect with a circuit.

[flux]
Further, the soluble conductor 15 is formed of a soluble conductor as shown in FIG. 2 in order to prevent the outer high-melting-point metal layer or the low-melting-point metal layer from being oxidized, to remove the oxide at the time of fusing, and to improve the solder fluidity. Flux 27 may be applied to the entire front and back surfaces of 15. By applying the flux 27, the wettability of the low melting point metal (for example, solder) is improved, and the oxide while the low melting point metal is dissolved is removed, and the erosion action to the high melting point metal (for example, silver) is achieved. It can be used to improve the fast fusing property.

  Also, when an anti-oxidation film such as Pb-free solder containing Sn as a main component is formed on the surface of the outermost refractory metal layer by applying the flux 27, the oxide of the anti-oxidation film is also changed. It can be removed, the refractory metal layer can be effectively prevented from being oxidized, and the fast fusing property can be maintained and improved.

[Cover member]
In the protection element 1, a cover member 19 that protects the inside and prevents the molten soluble conductor 15 from scattering is attached to the surface 10a of the insulating substrate 10 on which the soluble conductor 15 is provided. The cover member 19 can be formed of an insulating member such as various engineering plastics and ceramics. The cover member 19 is formed with a pair of opposing side walls 19a. The side walls 19a are installed on the surface 10a of the insulating substrate 10, and the terminal portions 20 of the fusible conductor 15 are connected to the insulating substrate 10 from two open side surfaces. It protrudes to the back surface 10b side.

  The protection element 1 is mounted with the back surface 10b side of the insulating substrate 10 facing the circuit board. As a result, since the fusible conductor 15 is covered with the cover member 19, the protective element 1 has the molten metal not only when fusing due to heat generated by the heating element 11 or when self-heating is interrupted due to occurrence of arc discharge due to overcurrent. It is captured by the cover member 19 and can be prevented from being scattered around.

[Protective element manufacturing process]
The protection element 1 is manufactured by the following steps. As shown in FIG. 4A, the insulating substrate 10 on which the soluble conductor 15 is mounted has a heating element 11, an insulating member 12, a heating element extraction electrode 13, a heating element electrode 16 and a pair of first elements on the surface 10a. A heat dissipation electrode 23 is formed. The insulating substrate 10 has an external connection terminal 18 that is continuous with the heating element electrode 16 through the through hole 17 on the back surface 10b. As shown in FIG. 4B, the terminal portions 20 of the fusible conductor 15 are fitted into the fitting recesses 21 formed on the pair of side edges of the insulating substrate 10, and the heating element lead-out electrode 13 and the The fusible conductor 15 is connected to one heat radiation electrode 23 through a bonding material such as solder for connection. Thereby, the fusible conductor 15 has the tip portion of the terminal portion 20 protruding toward the back surface 10b side of the insulating substrate 10.

  Next, as shown in FIG. 4C, a flux 27 is provided on the soluble conductor 15. By providing the flux 27, the soluble conductor 15 can be prevented from being oxidized and wettability can be improved, and can be blown quickly. Moreover, by providing the flux 27, adhesion of molten metal to the insulating substrate 10 can be suppressed, and insulation after fusing can be improved.

  Then, as shown in FIG. 4D, the protective element 1 is completed by mounting the cover member 19 that protects the surface 10a of the insulating substrate 10 and prevents the molten conductor 15 from scattering the molten conductor. To do. The cover member 19 is formed with a pair of opposing side walls 19a, the side walls 19a are installed on the front surface 10a, and the terminal portions 20 of the soluble conductor 15 are led out to the back surface 10b side from the two open side surfaces. Yes.

  The protection element 1 is mounted with the back surface 10b side of the insulating substrate 10 facing the circuit board. Thereby, the protection element 1 is connected to the land part in which both the terminal parts 20 of the soluble conductor 15 and the external connection terminal 18 are formed on the circuit board.

[How to use protection elements]
As shown in FIG. 5, the protection 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 protection 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 voltages 31 to 34 and a current control element 37 that controls the operation of the protection 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 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 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 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 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 protection element 1 to which the present invention is applied has a circuit configuration as shown in FIG. That is, the protective element 1 generates heat that melts the soluble conductor 15 by energizing the soluble conductor 15 connected in series via the heating element extraction electrode 13 and the connection point of the soluble conductor 15 to generate heat. This is a circuit configuration comprising the body 11. In the protection element 1, for example, the fusible conductor 15 is connected in series on the charge / discharge current path of the battery pack 30 via the terminal portion 20, and the heating element 11 is connected to the current control element 37. One of the pair of terminal portions 20 of the fusible conductor 15 is connected to the open end of the battery stack 35, and the other is connected to the open end of the battery pack on the positive electrode terminal 30a side. Further, the heating element 11 is connected to the charge / discharge current path of the battery pack 30 by being connected to the soluble conductor 15 via the heating element lead-out electrode 13, and via the heating element electrode 16 and the external connection terminal 18. The current control element 37 is connected.

  In the circuit configuration of the battery pack 30 which is a mounting body on which such a protective element 1 is mounted, the protective element 1 does not provide a through-hole in the insulating substrate 10 and draw out the energization path of the fusible conductor 15 to an external circuit. However, since the soluble conductor 15 is formed with the terminal portion 20 serving as a connection terminal to the external circuit, the conduction resistance between the external circuit and the soluble conductor 15 is determined by the resistance value of the soluble conductor 15 itself, It is not influenced by the configuration on the insulating substrate 10 side. Therefore, according to the protective element 1, it is possible to reduce the resistance of the energization path of the entire element and easily improve the current rating. As a result, the battery pack 30 has a current rating that is improved for the protective element 1 as a whole, and can handle a large current.

  Further, in the battery pack 30, when the heating element 11 of the protection element 1 generates heat, the soluble conductor 15 melts as shown in FIG. 3 and is drawn onto the heating element extraction electrode 13 due to its wettability. As a result, as shown in FIG. 6B, the protection element 1 can reliably cut off the current path when the soluble conductor 15 is melted. Further, since the fusible conductor 15 is blown, the power supply path to the heating element 11 is also cut off, so that the heating of the heating element 11 is also stopped.

  The protection element 1 to which the present invention is applied 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.

  Further, as shown in FIG. 7, the protection element 1 may fit the soluble conductor 15 to a pair of opposite side edges without providing the fitting recess 21 in the insulating substrate 10.

[Parallel type / insulating wall]
Further, as shown in FIG. 8, the protection element to which the present invention is applied may use a soluble conductor 51 in which a plurality of fusing parts 53 are arranged in parallel between a pair of terminal parts 52. In the following description, the same members as those of the protective element 1 described above are denoted by the same reference numerals and their details are omitted.

  The protective element 50 shown in FIG. 8 is laminated on the insulating substrate 10, the heating element 11 that is laminated on the surface 10 a of the insulating substrate 10, and covered with the insulating member 12, and the heating element 11 is superimposed on the insulating member 12. A soluble conductor 51 and a soluble conductor 51 which are fitted to a pair of opposing side edges of the insulating substrate 10 and are connected to the heating element extraction electrode 13 at the center are provided. And a cover member 19 that covers the surface 10a of the insulating substrate 10.

  The fusible conductor 51 is formed in a plate shape, and terminal portions 52 connected to an external circuit are provided at both ends. The fusible conductor 51 constitutes a part of the current path of the circuit board by connecting the terminal part 52 to the land part of the circuit board on which the protection element 50 is mounted. Cut off. The terminal portion 52 is directed to the back surface 10 b side of the insulating substrate 10 by fitting into the fitting recess 21 provided on the side edge of the insulating substrate 10.

  Further, the fusible conductor 51 has a plurality of fusing parts 53 formed between the pair of terminal parts 52. Each fusing part 53 is connected to the heating element extraction electrode 13 via a joining member such as a connecting solder. The fusible conductor 51 preferably contains a low-melting point metal layer and a high-melting point metal layer in the same manner as the fusible conductor 15 described above, and can be formed in various configurations as will be described later. .

  Below, the case where the meltable conductor 51 in which the three fusing parts 53A-53C were arranged in parallel is used as an example. As shown in FIG. 8A, the fusing parts 53 </ b> A to 53 </ b> C constitute a plurality of energization paths of the fusible conductor 51 by being mounted between the terminal parts 52. Then, the plurality of fusing parts 53A to 53C are cut off by the heat of the heating element 11, and all the fusing parts 53A to 53C are cut off to cut off the current path between the terminal parts 52.

  The fusible conductor 51 also melts when the current exceeding the rating is energized, so that each of the melted portions 53A to 53C is melted in sequence, so that the arc discharge generated when the last remaining melted portion 53 is melted. It is possible to prevent the molten fuse element from being scattered over a wide area, a new current path being formed by the scattered metal, or the scattered metal from adhering to the terminals and surrounding electronic components. it can. In addition, since the fusible conductor 51 is blown for each of the plurality of fusing parts 53A to 53C, the heat energy required for fusing each fusing part 53A to 53C is small, and can be cut off in a short time.

  Even if the soluble conductor 51 has a relatively high resistance by making the cross-sectional area of a part or all of one fusing part 53 out of a plurality of fusing parts 53 smaller than the cross-sectional area of another fusing part. Good. By increasing the resistance of one fusing part 53 relatively, when a current exceeding the rating is applied to the fusible conductor 51, a large amount of current is supplied from the fusing part 53 having a relatively low resistance and fusing. Go. Thereafter, the current concentrates on the remaining melted portion 53 with increased resistance, and finally melts with arc discharge. Therefore, the fusible conductor 51 can sequentially melt the fusing part 53. Moreover, since arc discharge is generated when the melted portion 53 having a small cross-sectional area is melted, the size of the melted portion 53 is reduced according to the volume of the melted portion 53, and the explosive scattering of the molten metal can be prevented.

  Moreover, it is preferable that the soluble conductor 51 is provided with three or more fusing parts, and the inner fusing part is blown out last. For example, as shown in FIG. 8, it is preferable that the fusible conductor 51 is provided with three fusing parts 53A, 53B, and 53C, and the middle fusing part 53B is blown last.

  When a current exceeding the rating is applied to the fusible conductor 51, first, a large amount of current flows through the two fusing parts 53A and 53C and fusing due to self-heating. Since fusing of the fusing parts 53A and 53C does not involve arc discharge due to self-heating, there is no explosive scattering of molten metal.

  Next, the current concentrates in the middle fusing part 53B and fusing with arc discharge. At this time, the fusible conductor 51 is blown out of the melted part 53B in the middle so that the melted metal in the melted part 53B is melted first, even if arc discharge occurs. It can be captured by 53C. Therefore, scattering of the molten metal in the melted part 53B can be suppressed, and a short circuit due to the molten metal can be prevented.

  At this time, the fusible conductor 51 is cut off from the other fusing parts 53A and 53C located outside the partial cross-sectional area of the middle fusing part 53B located on the inner side among the three fusing parts 53A to 53C. By making it smaller than the area, the resistance may be relatively increased, and the middle fusing part 53B may be blown out last. Also in this case, since the cross-sectional area is blown last by making the cross-sectional area relatively small, the arc discharge becomes small according to the volume of the blown portion 53B, and the explosive scattering of the molten metal is further suppressed. be able to.

[Production method of soluble conductor]
For example, as shown in FIG. 9A, the soluble conductor 51 in which such a plurality of fusing parts 53 are formed is a central part 2 of a plate-like body 54 containing a plate-like low melting point metal and a high melting point metal. After punching a place into a rectangular shape, it can be manufactured by bending both ends. The fusible conductor 51 is integrally supported by the terminal part 52 on both sides of the three fusing parts 53A to 53C arranged in parallel. Further, the provided soluble conductor 51 may be manufactured by connecting a plate-like body constituting the terminal portion 52 and a plurality of plate-like bodies constituting the fusing portion 53. As shown in FIG. 9B, in the fusible conductor 51, one end of the three fusing parts 53A to 53C arranged in parallel is integrally supported by the terminal part 52, and the terminal part 52 is formed at the other end, respectively. May be good.

[Heat radiation electrode]
The protection element 50 may be provided with a plurality of third heat dissipation electrodes 56 on the surface 10 a of the insulating substrate 10 in accordance with the fusing part 53. Similar to the first heat dissipation electrode 23 described above, the third heat dissipation electrode 56 is formed in the vicinity of the pair of side edges of the insulating substrate 10 to which the soluble conductor 51 is fitted, corresponding to each fusing part 53, By being connected to the fusing part 53, the heat of the soluble conductor 51 in the vicinity of the terminal part 52 is efficiently absorbed. The third heat dissipation electrode 56 can be formed using an electrode material such as Ag or Cu, and is connected to the fusing part 53 via a connection material such as a solder for connection.

  By providing the third heat radiating electrode 56, the protection element 50 radiates heat in the vicinity of the terminal portion 52 of the soluble conductor 51 to the insulating substrate 10 side, and the heat generating area of each fusing portion 53 is defined as the heating element extraction electrode 13. Concentrate on the central part connected with. Thereby, the melt | dissolving conductor 51 is limited to the center part of each fusing part 53, and can cut | disconnect an electric current path | route rapidly. Also, the fusible conductor 51 can prevent explosive fusing and scattering of the molten conductor by limiting the heat-generating part even when arc discharge is involved when the self-heating is interrupted due to overcurrent. In addition, the insulation properties are not impaired.

  As shown in FIG. 8B, the protective element 50 is also provided in the through hole 57 continuous with the third heat dissipation electrode 56 and the back surface 10b of the insulating substrate 10, and is continuous with the through hole 57. A fourth heat radiation electrode 58 is provided. Thereby, the protection element 50 can dissipate the heat of the soluble conductor 51 more efficiently.

[Insulating wall]
Further, as shown in FIG. 8, the protection element 50 may be provided with an insulating wall 55 between the plurality of fusing parts 53 to prevent connection between the fusing parts 53 arranged in parallel. By providing the insulating wall 55, the fusible conductor 51 melts and expands due to the heat generation of the heating element 11 or itself when the fusing part 53 is fusing, and contacts the adjacent fusing part 53 and aggregates. To prevent. As a result, the fusible conductor 51 increases in size by melting and agglomerating adjacent fusing parts 53, increasing the fusing time due to an increase in power necessary for fusing, lowering the insulation after fusing, or excessively. It is possible to prevent explosive scattering of the molten metal due to an increase in the scale of arc discharge that occurs at the time of fusing due to self-heating caused by current.

  For example, the insulating wall 55 is formed on the insulating member 12 covering the surface of the heating element 11 so as to straddle the heating element extraction electrode 13. The insulating wall 55 is erected by printing an insulating material such as solder resist or glass. Since the insulating wall 55 has insulating properties, it does not have wettability with respect to the molten conductor, and therefore it is not always necessary to completely isolate the adjacent fused portions 53 from each other. That is, even if there is a gap between the cover member 19 and the top surface 19b, the drawing action due to wettability does not work, and the molten conductor does not flow from the gap to the fusing part 53 side. Further, when the fusing part 53 is melted, it expands in a cross-sectional dome shape in the region between the terminal parts 52. Therefore, in the case where the interval between the fusing parts 53 is arranged to be narrower than twice the thickness of the fusible conductor 51, the insulating wall 55 is at least half the height from the heating element extraction electrode 13 to the top surface 19 b of the cover member 19. If the height is high, it is possible to prevent the molten conductor from coming into contact with the fusing part 53 arranged in parallel. Of course, the insulating wall 55 may be formed to a height up to the top surface 19b of the cover member 19 to isolate the fusing parts 53 from each other.

  Further, the insulating wall 55 may be formed on the top surface 19 b of the cover member 19. The insulating wall 55 may be integrally formed on the top surface 19b of the cover member 19, or may be erected by printing an insulating material such as solder resist or glass on the top surface 19b. In this case, the insulating wall 55 has a height from the top surface 19 b of the cover member 19 to the heating element extraction electrode 13, so that the molten conductor contacts the fusing part 53 that passes along the heating element extraction electrode 13 in parallel. Can be reliably prevented.

  Further, the insulating wall 55 is provided on the insulating substrate 10 and the cover member 19 and is formed by applying and curing a liquid or paste-like insulating material constituting the insulating wall 55 between a plurality of fusing parts 53 arranged in parallel. May be. As an insulating material constituting the insulating wall 55, a thermosetting insulating adhesive such as an epoxy resin, a solder resist, or a glass paste can be used. In this case, the insulating material constituting the insulating wall 55 may be applied and cured after the fusible conductor 51 is connected to the insulating substrate 10, and applied and cured before the fusible conductor 51 is connected to the insulating substrate 10. You may let them.

  The liquid or paste-like insulating material is filled by the capillary action between the plurality of fusing parts 53 arranged in parallel, and when the fusing parts 53 are melted by curing, the connection between the fusing parts 53 arranged in parallel is prevented. Can do. For this reason, it is calculated | required that the insulating material which comprises the insulating wall 55 is equipped with the heat resistance with respect to the heat_generation | fever temperature of the fusing part 53 by hardening | curing.

[Installation position of insulation part]
In addition, the protection element 50 should just provide the insulating wall 55 according to the melt | fusion part of the soluble conductor 51. FIG. As shown in FIG. 8, the fusible conductor 51 is superposed on the heating element 11 when each fusing part 53 is connected to the heating element extraction electrode 13, and the heat of the heating element 11 is transmitted through the heating element extraction electrode 13. It is transmitted to each fusing part 53. In addition, the fusible conductor 51 is formed between the terminal portions 52 provided at both ends of the fusible conductor 51 with each fusing portion 53, and current is not concentrated at the both ends 52, and is provided between the both ends 52. The current concentrates between the terminal portion 52 of each fusing portion 53 and the heating element extraction electrode 13 and melts by generating heat at a high temperature.

  Accordingly, when the interval between the fusing parts 53 is arranged to be narrower than twice the thickness of the fusible conductor 51, the protective element 50 is provided with the insulating wall 55 adjacent to the entire area of each fusing part 53, so It is possible to prevent contact with adjacent fusing parts 53.

  Further, when the interval between the fusing parts 53 is wider than twice the thickness of the fusible conductor 51, an insulating wall 55 is provided between the fusing parts 53 on the heating element extraction electrode 13, and at least the melt is drawn out from the heating element. The insulation wall 55 may be not higher than half of the height from the heating element extraction electrode 13 to the top surface 19b of the cover member 19.

[Control of fusing order]
The protection element 50 preferably has an insulating wall 55 between the fusing parts 53 of the fusible conductor 51. As a result, the melted portions 53 are prevented from melting and aggregating with each other, and an increase in fusing time due to an increase in power required for fusing and agglomeration of the molten conductor continues between the terminal portions 52 after fusing. It is possible to prevent the insulation from deteriorating.

  In addition, the protective element 50 sequentially melts the plurality of fusing parts 53 and provides an insulating wall 55 between at least the fusing part 53 that fusing first and the fusing part 53 adjacent to the fusing part 53 that flies first. It is preferable. As described above, the fusible conductor 51 has a relatively high resistance by making the cross-sectional area of a part or the whole of one fusing part 53 smaller than the cross-sectional area of the other fusing part among the plurality of fusing parts 53. When a current exceeding the rating is energized, a large amount of current is first energized and melted from the relatively low resistance fusing portion 53.

  At this time, the protective element 50 expands due to its own heat generation by providing an insulating wall 55 between the relatively low resistance melted portion 53 that is melted first and the melted portion adjacent to the melted portion 53. It is possible to prevent the adjacent melted portions 53 from being contacted and aggregated. As a result, the protection element 50 causes the fusing part 53 to be blown in a predetermined fusing order, and increases the fusing time due to the integration of the adjacent fusing parts 53 with each other. Can be prevented.

  Specifically, in the protective element 50 on which the fusible conductor 51 including the three fusing parts 53A, 53B, and 53C shown in FIG. 8 is mounted, the cross-sectional area of the middle fusing part 53B is relatively reduced and the resistance is increased. As a result, a large amount of current is preferentially passed from the outer fusing parts 53A and 53C to cause fusing, and finally, the middle fusing part 53B is blown. At this time, the protective element 50 is adjacent to the fusing parts 53A and 53B and adjacent to the fusing parts 53B and 53C even when the fusing parts 53A and 53C are melted by self-heating. While fusing in a short time without contacting the fusing part 53B, the fusing part 53B can be fusing finally. In addition, the melted portion 53B having a small cross-sectional area is not in contact with the adjacent melted portions 53A and 53C, and arc discharge at the time of melting is limited to a small scale.

  In addition, when the fusible conductor 51 is provided with three or more fusing parts, it is preferable that the outer fusing part is blown first and the inner fusing part is blown last. For example, as shown in FIG. 8, it is preferable that the fusible conductor 51 is provided with three fusing parts 53A, 53B, and 53C, and the middle fusing part 53B is blown last.

  As described above, when a current exceeding the rating is supplied to the fusible conductor 51, first, a large amount of current flows through the two fusing parts 53A and 53C provided on the outer side, and the fusing conductor 51 is blown by self-heating. Since fusing of these fusing parts 53A and 53C does not involve arc discharge due to self-heating, there is no explosive scattering of molten metal. Further, as described above, the fusing parts 53A and 53C are fused first without contact with the fusing part 53B adjacent to the insulating wall 55.

  Next, current concentrates on the fusing part 53B provided on the inner side, and fusing with arc discharge. At this time, the fusible conductor 51 is blown out of the melted metal of the melted portion 53B first by cutting the melted portion 53B provided inside at the end, even if arc discharge occurs. It can be captured by the insulating wall 55 provided between the parts 53A and 53C and the fusing parts 53A and 53C. Therefore, scattering of the molten metal in the melted part 53B can be suppressed, and a short circuit due to the molten metal can be prevented.

  Also at this time, the fusible conductor 51 includes the other fusing parts 53A and 53C located outside the partial cross-sectional area of the middle fusing part 53B located on the inner side among the three fusing parts 53A to 53C. By making it smaller than the cross-sectional area, the resistance may be relatively increased, and the middle fusing part 53B may be blown out last. Also in this case, since the cross-sectional area is blown last by making the cross-sectional area relatively small, the arc discharge becomes small according to the volume of the blown portion 53B, and the explosive scattering of the molten metal is further suppressed. be able to.

[Protective element manufacturing process]
The protection element 50 is manufactured by the following steps. As shown in FIG. 10A, the insulating substrate 10 on which the soluble conductor 51 is mounted has a heating element 11, an insulating member 12, a heating element extraction electrode 13, a heating element electrode 16 and a soluble conductor 51 on the surface 10a. The same number of third heat radiation electrodes 56 as the fusing parts 53 are formed. The insulating substrate 10 has an external connection terminal 18 that is continuous with the heating element electrode 16 through the through hole 17 on the back surface 10b. As shown in FIG. 10B, the terminal portions 52 of the fusible conductor 51 are fitted into the fitting recesses 21 formed on the pair of side edges of the insulating substrate 10, and the heating element lead-out electrode 13 and the Each fusing part 53 is connected to the heat radiation electrode 3 of 3 through a bonding material such as solder for connection. As a result, in the fusible conductor 51, the tip end portion of the terminal portion 52 projects toward the back surface 10 b side of the insulating substrate 10.

  Next, as shown in FIG. 10C, a flux 27 is provided on the soluble conductor 51. By providing the flux 27, the soluble conductor 51 can be prevented from being oxidized and wettability can be improved, and can be blown quickly. Moreover, by providing the flux 27, adhesion of molten metal to the insulating substrate 10 can be suppressed, and insulation after fusing can be improved.

  Then, as shown in FIG. 10D, the protection element 50 is completed by mounting the cover member 19 that protects the surface 10a of the insulating substrate 10 and prevents the molten conductor 51 from scattering the molten conductor. To do. The cover member 19 is formed with a pair of opposing side walls 19a, the side walls 19a are installed on the front surface 10a, and the terminal portions 52 of the soluble conductor 15 are led out to the back surface 10b side from the two open side surfaces. Yes.

  The protection element 50 is mounted with the back surface 10b side of the insulating substrate 10 facing the circuit board. Thereby, the protection element 1 is connected to the land portion in which the both terminal portions 52 of the fusible conductor 15 and the external connection terminal 18 are formed on the circuit board.

[Multiple soluble conductors]
Further, as shown in FIG. 11, the protection element to which the present invention is applied fits a plurality of soluble conductors corresponding to the fusing part 53 between a pair of opposite side edges of the insulating substrate 10 as soluble conductors. And may be parallel. In the following description, the same members as those of the protective elements 1 and 50 described above are denoted by the same reference numerals and their details are omitted.

  The protection element 60 shown in FIG. 11 is laminated on the insulating substrate 10, the heating element 11 covered with the insulating member 12, and laminated on the insulating member 12 so as to overlap the heating element 11. A plurality of fusible conductors 61 fitted to a pair of opposing side edges of the insulating substrate 10 and having a central portion connected to the heating element lead electrode 13, and a plurality of fusible conductors And a cover member 19 covering the surface 10a of the insulating substrate 10 provided with 61.

  The fusible conductor 61 has the same material and configuration as the fusible conductor 15 described above, and a plurality of, for example, three pieces, for example, 61A, 61B, and 61C, are arranged in parallel on the surface 10a of the insulating substrate 10. Each of the fusible conductors 61A to 61C is formed in a rectangular plate shape, and terminal portions 62 are bent at both ends. Each terminal part 62 provided in the fusible conductors 61A to 61C is connected to a land part provided on the circuit board of the external circuit, thereby constituting a part of the current path of the circuit board and fusing. This interrupts the current path. The terminal portion 62 is directed to the back surface 10 b side of the insulating substrate 10 by fitting into the fitting recess 21 provided on the side edge of the insulating substrate 10.

  Each soluble conductor 61 has a central portion placed on the surface 10a of the insulating substrate 10 connected to the heating element extraction electrode 13 via a joining member such as a solder for connection. The fusible conductor 61 preferably contains a low-melting point metal layer and a high-melting point metal layer in the same manner as the fusible conductor 15 described above, and can be formed in various configurations as will be described later. .

  The protective element 60 is relatively made by making the cross-sectional area of the middle soluble conductor 61B provided on the inner side smaller than the cross-sectional areas of the other soluble conductors 61A and 61C provided on the outer side. The resistance may be increased, and when self-heating is interrupted due to overcurrent, it may be melted last.

  Moreover, the protective element 60 may form the insulating wall 55 between each soluble conductor 61A-61C similarly to the protective element 50 mentioned above. By providing the insulating wall 55, the protection element 60 melts and expands due to the heat generation of the heating element 11 or itself when the soluble conductors 61 are melted and contacts the adjacent soluble conductors 61 to aggregate. To prevent that. As a result, the protective element 60 increases in size by melting and aggregating adjacent fusible conductors 61, increasing the fusing time due to an increase in power required for fusing, reducing the insulation after fusing, or excessively. It is possible to prevent explosive scattering of the molten metal due to an increase in the scale of arc discharge that occurs at the time of fusing due to self-heating caused by electric current.

  As shown in FIG. 11B, also in the protection element 60, a plurality of fifth heat radiation electrodes 63 and fifth heat radiations are provided in the vicinity of the side edge of the insulating substrate 10 corresponding to each soluble conductor 61. A through hole 64 that is continuous with the member 63 and a sixth heat radiation electrode 65 that is provided on the back surface 10 b of the insulating substrate 10 and is continuous with the through hole 64 are provided. Thereby, the protection element 60 can dissipate the heat of each soluble conductor 61 more efficiently.

[Flip type]
Moreover, as shown in FIGS. 12 and 13, the protection element to which the present invention is applied may have the terminal portion of the soluble conductor projecting toward the surface 10 a side of the insulating substrate 10. In the following description, the same members as those of the protective elements 1, 50, 60 described above are denoted by the same reference numerals, and the details thereof are omitted. 12A is an external perspective view showing the bottom surface side of the protection element 70, and FIG. 1B is an external perspective view showing the top surface side of the protection element 70. FIG. 13A is a plan view in which the cover member of the protection element 70 is omitted, and FIG. 13B is a cross-sectional view taken along the line AA ′ of the protection element 70 shown in FIG.

  The protection element 70 is laminated on the insulating substrate 10, the surface 10 a of the insulating substrate 10, and the heating element 11 covered with the insulating member 12, and the heating element laminated on the insulating member 12 so as to overlap the heating element 11. The lead electrode 13 is disposed on the surface 10a of the insulating substrate 10 and covers the soluble conductor 71 whose central portion is connected to the heating element extraction electrode 13 and the surface 10a of the insulating substrate 10 provided with the soluble conductor 71. And a cover member 19.

  The fusible conductor 71 is formed in a plate shape like the fusible conductor 51 described above, and terminal portions 72 connected to an external circuit are provided at both ends. The fusible conductor 71 constitutes a part of the current path of the circuit board by the terminal part 72 being connected to the land part of the circuit board on which the protective element 70 is mounted, and the current path is formed by fusing. Cut off. The terminal portion 72 is directed to the surface 10 a side of the insulating substrate 10 by mounting the soluble conductor 71 on the surface 10 a of the insulating substrate 10.

  Further, the fusible conductor 71 has a plurality of fusing parts 73 formed between the pair of terminal parts 72. Each fusing part 73 is connected on the heating element lead-out electrode 13 via a joining member such as a connecting solder. The fusible conductor 71 preferably contains a low-melting point metal layer and a high-melting point metal layer in the same manner as the fusible conductor 15 described above, and can be formed in various configurations as will be described later. .

  In addition, the protection element 70 may use the soluble conductor 71 of the flat plate shape which does not have the some fusing part 73 similarly to the soluble conductor 15.

  Further, the protective element 70 is provided with an external connection terminal 74 on the heating element electrode 16. The external connection terminal 74 is a terminal that is connected to an external circuit by drawing the heating element electrode 16 onto the surface 10a of the insulating substrate 10, and for example, a columnar or spherical metal bump can be used.

  Such a protective element 70 includes the terminal portion 72 of the fusible conductor 71 and the external connection terminal 74 connected to the heating element electrode 16 projecting on the surface 10a of the insulating substrate 10, whereby the surface 10a side of the insulating substrate 10 is provided. Are mounted on the circuit board of the external circuit, and are connected by face-down.

  As shown in FIG. 13, also in the protective element 70, a plurality of seventh heat radiation electrodes 75 are provided in the vicinity of the side edge of the insulating substrate 10 in correspondence with the fusing portions 73 of the fusible conductor 71. . Thereby, the protection element 70 can dissipate heat at both ends of each fusing part 73 more efficiently, and heat and blow the central part intensively.

  The protection element 70 is manufactured by the following process. As shown in FIG. 14A, the insulating substrate 10 on which the soluble conductor 71 is mounted has a heating element 11, an insulating member 12, a heating element extraction electrode 13, a heating element electrode 16 and a soluble conductor 71 on the surface 10a. A plurality of seventh heat radiation electrodes 75 are formed corresponding to the fusing part 73. As shown in FIG. 14B, the central portion of each melted portion 72 of the fusible conductor 71 is connected to the heating element lead-out electrode 13 formed on the surface 10a of the insulating substrate 10 via a bonding material such as solder for connection. Connect. As a result, in the fusible conductor 71, the tip end portion of the terminal portion 72 protrudes toward the surface 10 a side of the insulating substrate 10. Further, the external connection terminal 74 is connected to the heating element electrode 16 through a bonding material such as connection solder.

  Next, as shown in FIG. 14C, a flux 27 is provided on the soluble conductor 71. By providing the flux 27, the soluble conductor 71 can be prevented from being oxidized and wettability can be improved, and can be blown quickly. Moreover, by providing the flux 27, adhesion of the molten metal to the insulating substrate 10 due to arc discharge can be suppressed, and insulation after fusing can be improved.

  Then, as shown in FIG. 14D, the protection element 70 is completed by mounting the cover member 19 that protects the surface 10a of the insulating substrate 10 and prevents the molten conductor 71 from scattering the molten conductor. To do. The cover member 19 is formed with a pair of opposing side walls 19a, the side walls 19a are installed on the surface 10a, and the terminal portions 72 of the soluble conductor 71 are led out to the surface 10a side from the two open side surfaces. Yes.

  The protection element 70 is mounted with the surface 10ab side of the insulating substrate 10 facing the circuit board. As a result, the protective element 70 is connected to the land portion where the both terminal portions 72 and the external connection terminals 74 of the fusible conductor 71 are formed on the circuit board.

[Heating element position]
The protective elements 1, 50, 60, and 70 described above may be provided on the back surface 10 b of the insulating substrate 10 in addition to stacking the heating element 11 on the front surface 10 a of the insulating substrate 10. FIG. 15A shows a configuration in which the heating element 11 is provided on the back surface 10b of the insulating substrate 10 in the protection elements 1, 50, 60, and FIG. The structure provided in 10b is shown.

  In any case, the heating element 11 is covered with the insulating member 12 on the back surface 10 b of the insulating substrate 10. Further, the heating element electrode 13 constituting the power supply path to the heating element 11 has a lower layer portion 13 a connected to the heating element 11 formed on the back surface 10 b of the insulating substrate 10 and an upper layer portion 13 b connected to the soluble conductor 15. Is formed on the surface 10a of the insulating substrate 10, and the lower layer portion 13a and the upper layer portion 13b are continued through the conductive through hole. The heating element 11 is preferably formed at a position overlapping the heating element extraction electrode 13 on the back surface 10 b of the insulating substrate 10.

  Further, the protection elements 1, 50, 60 and 70 may form the heating element 11 inside the insulating substrate 10. FIG. 16A shows a configuration in which the heating element 11 is provided in the insulating substrate 10 in the protection elements 1, 50, and 60, and FIG. 16B shows the heating element 11 in the insulating substrate 10 in the protection element 70. The provided structure is shown.

  In either case, it is not necessary to provide the insulating member 12 that covers the heating element 11. The heating element 11 is preferably formed at a position overlapping the upper layer portion 13 b of the heating element extraction electrode 13 in the insulating substrate 10.

  Further, in the protection elements 1, 50, 60, the heating element electrode 16 is connected to one end of the heating element 11 by being formed inside the insulating substrate 10, and is connected to the back surface 10 b of the insulating substrate 10 through the conductive through hole. It is connected to the external connection terminal 18 provided. The heating element lead-out electrode 13 has a lower layer portion 13a connected to the heating element 11 formed to the inside of the insulating substrate 10, an upper layer portion 13b on which the soluble conductor 15 is mounted is formed on the surface 10a of the insulating substrate 10, and a lower layer portion The portion 13a and the upper layer portion 13b are continued through the conductive through hole.

  In the protection element 70, the heating element electrode 16 is provided inside the insulating substrate 10 and is provided on a lower layer (not shown) connected to one end of the heating element 11, the surface 10 a of the insulating substrate 10, and an external connection terminal. 74 is connected to the upper layer portion (not shown), and the lower layer portion and the upper layer portion are continued through the conductive through hole. Similarly, in the heating element extraction electrode 13, the lower layer portion 13a connected to the heating element 11 is formed up to the inside of the insulating substrate 10, and the upper layer portion 13b on which the soluble conductor 15 is mounted is formed on the surface 10a of the insulating substrate 10. Then, the lower layer portion 13a and the upper layer portion 13b are continued through the conductive through hole.

  Further, the protective elements 1, 50, 60, and 70 are formed by forming the heating element 11 on the surface 10a of the insulating substrate 10 and arranging the heating element 11 and the soluble conductors 15, 51, 61, and 71 adjacent to each other. Also good. FIG. 17 shows a configuration in which the heating element 11 and the soluble conductor 15 are arranged adjacent to each other on the surface 10 a of the insulating substrate 10 in the protection element 1. The heating elements 11 of the protection elements 1, 50, 60, and 70 are covered with the insulating member 12 and connected to one end of the heating element extraction electrode 13 provided on the surface 10 a of the insulating substrate 10.

  In the protective elements 1, 50, 60, and 70, the heating element 11 is formed on the back surface 10 b or inside of the insulating substrate 10, or the heating element 11 and the soluble conductors 15, 51, 61, 71 are on the surface of the insulating substrate 10. As a result, the surface 10a of the insulating substrate 10 is flattened, whereby the heating element extraction electrode 13 can be formed on the surface 10a. Therefore, the protection elements 1, 50, 60, and 70 can simplify the manufacturing process of the heating element extraction electrode 13 and can reduce the height.

  Further, the protective element 1 uses a material having excellent thermal conductivity such as fine ceramic as the material of the insulating substrate 10 even when the heating element 11 is formed on the back surface 10 b of the insulating substrate 10 or inside the insulating substrate 10. Thus, the fusible conductors 15, 51, 61, 71 can be heated and blown by the heating element 11 in the same manner as when laminated on the surface 10 a of the insulating substrate 10.

[Configuration of soluble conductor]
As described above, the soluble conductors 15, 51, 61, 71 may contain a low melting point metal and a high melting point metal. Below, although the structure of the soluble conductor 15 is demonstrated, the soluble conductors 51, 61, 71 can also be set as the same structure. As shown in FIG. 18A, the soluble conductor 15 may have a configuration in which a low melting point metal layer 91 is provided as an inner layer and a high melting point metal layer 90 is provided as an outer layer. In this case, the soluble conductor 15 may have a structure in which the entire surface of the low-melting-point metal layer 91 is covered with the high-melting-point metal layer 90, or may have a structure in which a pair of opposite side surfaces are covered. The covering structure of the low melting point metal layer 91 by the high melting point metal layer 90 can be formed using a known film forming technique such as plating.

  As shown in FIG. 18B, the soluble conductor 15 may have a configuration in which a high melting point metal layer 90 is provided as an inner layer and a low melting point metal layer 91 is provided as an outer layer. Also in this case, the soluble conductor 15 may have a structure in which the entire surface of the high melting point metal layer 90 is covered with the low melting point metal layer 91, or may have a structure in which a pair of side surfaces facing each other are covered.

  Further, the soluble conductor 15 may have a laminated structure in which a high melting point metal layer 90 and a low melting point metal layer 91 are laminated as shown in FIG.

  In this case, the soluble conductor 15 is formed as a two-layer structure consisting of a lower layer connected to the heating element extraction electrode 13 and an upper layer laminated on the lower layer, as shown in FIG. The upper refractory metal layer 90 may be laminated on the upper surface of the low-melting-point metal layer 91, or the upper low-melting-point metal layer 91 may be laminated on the upper surface of the lower-melting-point metal layer 90. Good. Alternatively, the soluble conductor 15 may be formed as a three-layer structure including an inner layer and an outer layer laminated on the upper and lower surfaces of the inner layer, as shown in FIG. 19B, and the low melting point metal layer 91 serving as the inner layer. The refractory metal layer 90 serving as the outer layer may be laminated on the upper and lower surfaces of the refractory metal, and the low melting metal layer 91 serving as the outer layer may be laminated on the upper and lower surfaces of the refractory metal layer 90 serving as the inner layer.

  Further, as shown in FIG. 20, the soluble conductor 15 may have a multilayer structure of four or more layers in which the high melting point metal layers 90 and the low melting point metal layers 91 are alternately laminated. In this case, the soluble conductor 15 is good also as a structure coat | covered by the metal layer which comprises outermost layer except the whole surface or a pair of side surface which opposes.

  In the soluble conductor 15, the high melting point metal layer 90 may be partially laminated in a stripe shape on the surface of the low melting point metal layer 91 constituting the inner layer. FIG. 21 is a plan view of the fusible conductor 15.

  The soluble conductor 15 shown in FIG. 21A is formed by forming a plurality of linear refractory metal layers 90 in the longitudinal direction at predetermined intervals in the width direction on the surface of the low melting point metal layer 91. A linear opening 92 is formed along the opening, and the low melting point metal layer 91 is exposed from the opening 92. The fusible conductor 15 exposes the low melting point metal layer 91 from the opening 92, thereby increasing the contact area between the molten low melting point metal and the high melting point metal, and further promoting the corrosion action of the high melting point metal layer 90. The fusing property can be improved. The opening 92 can be formed, for example, by subjecting the low melting point metal layer 91 to partial plating of a metal constituting the high melting point metal layer 90.

  Further, as shown in FIG. 21B, the soluble conductor 15 is formed by forming a plurality of linear refractory metal layers 90 in the width direction on the surface of the low melting point metal layer 91 at predetermined intervals in the longitudinal direction. Thus, a linear opening 92 may be formed along the width direction.

  In addition, as shown in FIG. 22, the fusible conductor 15 has a high melting point metal layer 90 formed on the surface of the low melting point metal layer 91 and a circular or rectangular opening over the entire surface of the high melting point metal layer 90. A portion 93 may be formed, and the low melting point metal layer 91 may be exposed from the opening 93. The opening 93 can be formed, for example, by subjecting the low melting point metal layer 91 to partial plating of a metal constituting the high melting point metal layer 90.

  The fusible conductor 15 is exposed to the low melting point metal layer 91 through the opening 93, so that the contact area between the molten low melting point metal and the high melting point metal is increased, and the erosion action of the high melting point metal is further promoted. Can be improved.

  In addition, as shown in FIG. 23, the fusible conductor 15 has a large number of openings 94 formed in the refractory metal layer 90 serving as an inner layer, and the refractory metal layer 90 is formed with a low melting point metal using a plating technique or the like. The layer 91 may be formed and filled in the opening 94. As a result, the fusible conductor 15 has an increased area where the low-melting-point metal is in contact with the high-melting-point metal, so that the low-melting-point metal can corrode the high-melting-point metal in a shorter time.

  The soluble conductor 15 is preferably formed such that the volume of the low melting point metal layer 91 is larger than the volume of the high melting point metal layer 90. The soluble conductor 15 is heated by the heating element 11 to melt the high melting point metal by melting the low melting point metal, and thereby can be melted and blown quickly. Therefore, the soluble conductor 15 promotes this corrosion action by forming the volume of the low-melting-point metal layer 91 larger than the volume of the high-melting-point metal layer 90, and quickly cuts off the current path of the external circuit. be able to.

  Further, as shown in FIG. 24, the fusible conductor 15 is formed in a substantially rectangular plate shape, and is covered with a refractory metal constituting the outer layer, and is formed with a pair of opposing first electrodes formed thicker than the main surface portion 15a. 1 side edge portion 15b, and a pair of second side edge portions 15c opposed to each other and formed with a thickness lower than that of the first side edge portion 15b where the low melting point metal constituting the inner layer is exposed. May be.

  The side surface of the first side edge portion 15 b is covered with the refractory metal layer 90 and is thereby formed thicker than the main surface portion 15 a of the soluble conductor 15. The second side edge 15c has a low-melting-point metal layer 91 whose outer periphery is surrounded by the high-melting-point metal layer 90 on the side surface. The second side edge portion 15c is formed to have the same thickness as the main surface portion 15a except for both end portions adjacent to the first side edge portion 15b.

  As shown in FIG. 25, the fusible conductor 15 configured as described above has both end portions provided with the first side edge portion 15 b as the terminal portion 20, and the second side edge portion 15 c as the insulating substrate 10. Between a pair of side edges.

  Thereby, the protection element 1 can prevent the fluctuation | variation of the rating and interruption | blocking time by deformation | transformation of the soluble conductor 15 at the time of reflow mounting, the energization of a rated current, etc. Moreover, the protection element 1 can melt | dissolve the soluble conductor 15 quickly after heat_generation | fever of the heat generating body 11, and can interrupt | block the electric current path of an external circuit.

  That is, the first side edge portion 15b is covered with a high melting point metal, and the low melting point metal layer 91 is not exposed. Therefore, the erosion action hardly occurs, and a lot of heat energy is required until melting. Therefore, by using the first side edge portion 15b as the terminal portion 20, the fusible conductor 15 is connected to the land portion of the external circuit by heating at the time of reflow mounting or by self-heating by energizing the rated current. Even when the solder for melting is melted, the first side edge 15b coated with the high melting point metal is melted, and the low melting point metal constituting the inner layer is pulled by the connecting solder and flows out to the land portion having excellent wettability. Is prevented. Therefore, the fusible conductor 15 is prevented from being deformed due to the outflow of the low melting point metal, maintains a predetermined rating, and prevents the melting time from being prolonged due to the inhibition of the erosion action due to the outflow of the low melting point metal. Can do.

  Further, the second side edge 15c is formed to be relatively thinner than the first side edge 15b. Further, the low melting point metal layer 91 constituting the inner layer is exposed on the side surface of the second side edge portion 15c. As a result, the second side edge 15c acts to cause the erosion of the refractory metal layer 90 by the low melting point metal layer 91, and the thickness of the refractory metal layer 90 to be eroded is also the first side edge. By being formed thinner than 15b, it can be rapidly melted with less heat energy than the first side edge 15b formed thick by the high melting point metal layer 90.

  Therefore, in the protection element 1, the second side edge portion 15c is quickly melted by the heat generating body 11 generating heat, the molten conductor is aggregated on the heat generating body lead electrode 13, and the gap between the pair of terminal portions 20 is increased. It can melt and cut off the current path of the external circuit.

  The soluble conductor 15 having such a configuration is manufactured by coating a low melting point metal foil such as a solder foil constituting the low melting point metal layer 91 with a metal such as Ag constituting the high melting point metal layer 90. . As a method for coating a low melting point metal layer foil with a high melting point metal, an electrolytic plating method capable of continuously applying a high melting point metal plating to a long low melting point metal foil is advantageous in terms of work efficiency and manufacturing cost. It becomes.

  When the refractory metal plating is performed by electrolytic plating, the current density is relatively increased at the edge portion of the long low melting point metal foil, that is, the side edge portion, and the refractory metal layer 90 is thickly plated (FIG. 24). reference). As a result, a long conductor ribbon 96 having side edges formed thick by the refractory metal layer is formed. Next, the conductor ribbon 96 is cut into a predetermined length in the width direction (C-C ′ direction in FIG. 24) orthogonal to the longitudinal direction, whereby the soluble conductor 15 is manufactured. Thereby, as for the soluble conductor 15, the side edge part of the conductor ribbon 96 becomes the 1st side edge part 15b, and the cut surface of the conductor ribbon 96 becomes the 2nd side edge part 15c. The first side edge 15b is covered with a refractory metal, and the second side edge 15c is formed of a refractory metal layer 90 and a refractory metal layer surrounding the outer periphery of the end face (cut surface of the conductor ribbon 96). A low melting point metal layer 91 sandwiched by 90 is exposed to the outside.

DESCRIPTION OF SYMBOLS 1 Protection element, 10 Insulating board | substrate, 10a surface, 10b back surface, 11 Heating body, 12 Insulating member, 13 Heating body extraction electrode, 15 Soluble conductor, 15a Main surface part, 15b 1st side edge part, 15c 2nd side Edge part, 16 Heating element electrode, 17 Through hole, 18 External connection terminal, 19 Cover member, 20 Terminal part, 21 Fitting recess, 23 First heat radiation electrode, 24 Through hole, 25 Second heat radiation electrode, 27 Flux 30 battery pack, 30a positive terminal, 30b negative terminal, 31-34 battery cell, 35 battery stack, 36 detection circuit, 37 current control element, 40 charge / discharge control circuit, 41 current control element, 42 current control element, 43 control Part, 45 charging device, 50 protective element, 51 soluble conductor, 52 terminal part, 53 fusing part, 54 plate-like body, 55 Wall, 56 3rd heat radiation electrode, 60 protection element, 61 soluble conductor, 62 terminal part, 70 protection element, 71 soluble conductor, 72 terminal part, 73 fusing part, 74 external connection terminal, 90 refractory metal layer, 91 Low melting point metal layer, 92-94 opening, 96 conductor ribbon

Claims (28)

An insulating substrate;
A heating element disposed on the insulating substrate;
A heating element extraction electrode electrically connected to the heating element;
By being fitted to the insulating substrate, it is arranged on the surface of the insulating substrate and melted by heat, and both ends are provided along the side surface of the insulating substrate, and are directed to the back surface side. and a pair of terminal portions to be connected to the protective element and a fusible conductor to cut off the current path of the external circuit by between the pair of terminal portions is blown. The protective element according to claim 1, wherein the soluble conductor is formed in a rectangular plate shape, and the terminal portion is bent along a side surface of the insulating substrate. The protective element according to claim 1, wherein the soluble conductor and the heating element extraction electrode are connected.   The protection element according to claim 1, wherein the insulating substrate has a fitting recess into which the soluble conductor is fitted. An insulating substrate;
A heating element disposed on the insulating substrate;
A heating element extraction electrode electrically connected to the heating element;
A pair of terminal portions connected to an external circuit, and a fusible conductor that blocks a current path of the external circuit by fusing between the pair of terminal portions,
The fusible conductor is disposed on the surface of the insulating substrate and is provided at both ends of the fusing portion that is melted by heat and the fusing portion, and the pair of terminals protruding from the fusing portion to the surface side of the insulating substrate. And
A heating element electrode formed on the surface of the insulating substrate and connected to an open end of the heating element;
A protective element having an external connection terminal protruding to the surface side of the insulating substrate by being connected to the heating element electrode.   The protection element according to any one of claims 1 to 5, wherein a heat radiation electrode connected to the soluble conductor and absorbing heat of the soluble conductor is provided on a surface of the insulating substrate.   The protection element according to claim 6, wherein the heat dissipation electrode is continuous with a terminal portion provided on a back surface of the insulating substrate through a through hole.   The protection element according to any one of claims 1 to 7, wherein the fusible conductor has a plurality of fusing portions arranged in parallel between the pair of terminal portions.   The protection element according to claim 8, wherein an insulating wall or an insulating layer provided on the heating element extraction electrode is provided between the plurality of fusing parts.   The plurality of the soluble conductors are arranged in parallel, and an insulating layer or an insulating layer provided on the heating element extraction electrode is provided between the soluble conductors. The protective element as described. The heating element is formed on the surface of the insulating substrate and covered with the insulating member, or formed inside the insulating member formed on the surface of the insulating substrate,
The protection element according to claim 1, wherein the heating element extraction electrode is formed on the insulating member.   The protective element according to claim 1, wherein the heating element is formed on a back surface of the insulating substrate and is covered with an insulating member.   The protection element according to claim 1, wherein the heating element is formed inside the insulating substrate. The heating element is formed on the surface of the insulating substrate,
The said soluble conductor is a protection element of any one of Claims 1-10 arrange | positioned adjacent to the said heat generating body on the surface of the said insulated substrate. The soluble conductor has a low melting point metal layer and a high melting point metal layer,
The protective element according to any one of claims 1 to 14, wherein the low melting point metal layer erodes and melts the high melting point metal layer.   The protection element according to claim 15, wherein the low melting point metal is Sn or an alloy containing 40% or more of Sn, and the high melting point metal is Ag, Cu, or an alloy containing Ag or Cu as a main component.   The protection element according to claim 15 or 16, wherein the soluble conductor has an inner layer made of a high melting point metal and an outer layer made of a low melting point metal.   The protective element according to claim 15 or 16, wherein the soluble conductor has an inner layer made of a low melting point metal and an outer layer made of a high melting point metal.   The protective element according to claim 15 or 16, wherein the soluble conductor has a laminated structure in which a low melting point metal and a high melting point metal are laminated.   The protection element according to claim 15 or 16, wherein the soluble conductor has a multilayer structure of four or more layers in which a low melting point metal and a high melting point metal are alternately laminated.   The protection element according to claim 15 or 16, wherein the soluble conductor is provided with an opening in a high melting point metal formed on a surface of a low melting point metal constituting an inner layer.   The soluble conductor has a high melting point metal layer having a number of openings and a low melting point metal layer formed on the high melting point metal layer, and the opening is filled with a low melting point metal. Item 15. The protective element according to Item 15 or 16. The fusible conductor is covered with the refractory metal, and a pair of opposing first side edges formed thicker than the main surface portion; and
A pair of second side edges facing each other, wherein the low-melting-point metal layer forming the inner layer is exposed from the high-melting-point metal layer, which is formed thinner than the first side surface, Have
The protective element according to claim 15 or 16, wherein a pair of the first side edge portions are the terminal portions.   The protection element according to any one of claims 15 to 23, wherein the soluble conductor has a volume of a low melting point metal larger than a volume of the high melting point metal.   The protective element according to any one of claims 1 to 24, wherein the surface of the heating element extraction electrode is coated with any one of Ni / Au plating, Ni / Pd plating, and Ni / Pd / Au plating.   The flux is coated on a part or all of the surface of the soluble conductor, and the fused portion of the soluble conductor and the flux are covered with a cover member provided on the insulating substrate. The protective element according to any one of the above. In the mounting body in which the protective element is mounted on the circuit board,
The protective element is
An insulating substrate;
A heating element disposed on the insulating substrate;
A heating element extraction electrode electrically connected to the heating element;
By being fitted to the insulating substrate, it is arranged on the surface of the insulating substrate and melted by heat, and both ends are provided along the side surface of the insulating substrate, and are directed to the back surface side. And a fusible conductor that cuts off the current path of the external circuit by fusing between the pair of terminal portions. In the mounting body in which the protective element is mounted on the circuit board,
The protective element is
An insulating substrate;
A heating element disposed on the insulating substrate;
A heating element extraction electrode electrically connected to the heating element;
A pair of terminal portions connected to an external circuit, and a fusible conductor that blocks a current path of the external circuit by fusing between the pair of terminal portions,
The fusible conductor is disposed on the surface of the insulating substrate and is provided at both ends of the fusing portion that is melted by heat and the fusing portion, and the pair of terminals protruding from the fusing portion to the surface side of the insulating substrate. And
A heating element electrode formed on the surface of the insulating substrate and connected to an open end of the heating element;
A mounting body having an external connection terminal protruding to the surface side of the insulating substrate by being connected to the heating element electrode.

Images