JP2014044955A - Protection element, and battery pack - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a protection element capable of stopping heat generation of a heating resistor with certainty after all fuse elements are melted even when energized only from a specific energization path.SOLUTION: A protection element is configured to control melting times of a plurality of fuse elements 12a and 12b so that a specific fuse element among the plurality of fuse elements 12a and 12b is melted after other fuse element is melted when energized from a specific energization path to which the specific fuse element is connected.

Description

  The present invention relates to a protective element that cuts off a current by fusing a low melting point metal body in an abnormal state, and a battery pack on which the protective element is mounted.

  As a protective element that can be used to prevent not only overcurrent but also overvoltage, a protective element in which a heating resistor and a low-melting-point metal body (fuse element) are stacked on a substrate is known (for example, Patent Document 1 and (See Patent Document 2 etc.). In the protective elements described in Patent Document 1 and Patent Document 2, the heating resistor is energized at the time of abnormality, and the heat generating resistor generates heat, so that the fuse element is melted. In this protective element, the melted fuse element is drawn onto the electrode due to the good wettability with respect to the electrode surface on which the fuse element is placed. As a result, in the protection element, the fuse element is blown and the current is interrupted.

Japanese Patent No. 2790433 Japanese Patent No. 3067011

  By the way, in the protection element, when there are a plurality of energization paths (power input) to the fuse element, that is, in the case of a configuration aiming to block all the energization paths, there is no energization from a specific energization path In some cases, the energization path is not interrupted with a certain probability.

  Specifically, as shown in FIG. 5, two fuse elements 102a and 102b are arranged so as to be bridged between three fuse element electrodes 101a, 101b and 101c. Consider a protective element in which a heating resistor 104 is connected between 101 b and a heating resistor electrode 103. In this protection element, two paths from the fuse element electrodes 101a and 101c on both sides to the center fuse element electrode 101b are energized paths. In this case, when the protective element is energized from both of the two energization paths as shown in the first stage in FIG. 5 and the heating resistor 104 generates heat, it is shown in the second stage in FIG. In addition, when both of the two fuse elements 102a and 102b are fused, all the energization paths are cut off, and the heat generation of the heating resistor 104 is stopped.

  Here, as shown in the first row in FIG. 6, energization is performed only from one energization path from the left fuse element electrode 101 a to the center fuse element electrode 101 b, and the heating resistor 104 generates heat. think of. In this case, in the protective element, as shown in the left side of the second stage in FIG. 6, when the fuse element 102b that is not energized blows first, the energization is performed as shown in the third stage in FIG. The fuse element 102a that has been made is also melted and all the energization paths are cut off, and the heat generation of the heating resistor 104 is stopped. However, in the protective element, as shown on the right side of the second stage in FIG. 6, when the energized fuse element 102a is blown first, the non-energized fuse element 102b is blown. Inability to do so will result in a situation where all energization paths are not blocked. In the protective element, when there are two fuse elements, such a situation occurs with a probability of 1/2, and with a probability corresponding to the number of fuse elements.

  Such a situation is seen in the protective element 110 mounted on a battery pack that is attached to and detached from an electronic device main body such as a notebook personal computer, for example, as shown in FIG. That is, in such a battery pack, it is normally assumed that there is energization from both the cell side and the charger side of the electronic device body, but when the battery pack is removed from the electronic device body, , The charger is not connected to the protection element 110. Therefore, in such a case, the protective element 110 is not energized from the charger side, which may cause a situation as shown on the right side of the second stage in FIG.

  The present invention has been made in view of such circumstances, and even when power is supplied only from a specific power supply path, heat generation of the heating resistor is stopped after surely fusing all the fuse elements. It is an object of the present invention to provide a protective element that can be applied.

  In the protection element according to the present invention that achieves the above-described object, a plurality of fuse elements are disposed between a plurality of electrodes serving as inputs to the energization path, and a current is generated by fusing of the fuse elements due to heat generated by the energized heating element. In the protection element to be shut off, when power is supplied from a specific current path to which a specific fuse element is connected among the plurality of fuse elements, the other fuse elements are blown before the specific fuse element. As described above, the fusing time of the plurality of fuse elements is configured to be controllable, and the specific electrode to which the specific fuse element is connected is a current-carrying path that is always energized among the plurality of electrodes. The fusing time of the specific fuse element is the other input of the fuse element. To be longer than the cross-sectional time, it is characterized respectively of the plurality of fuse elements, that there is a difference between the wettability between each of the plurality of electrodes.

  In such a protection element according to the present invention, the fusing time of the fuse element can be controlled. In other words, the protection element according to the present invention is configured to be able to identify a fuse element having a long fusing time among a plurality of fuse elements. Therefore, in the protection element according to the present invention, when energization is performed from the energization path to which a specific fuse element having a long fusing time is connected, all other fuse elements can be fused first.

  According to the present invention, when energization is performed from an energization path to which a specific fuse element having a long fusing time is connected, all other fuse elements can be fused first. Even if there is no energization from, after the specific fuse element is blown, that is, after all the fuse elements have been surely blown, it is possible to cut off the energization to stop the heat generation. And safety can be greatly improved.

It is a top view explaining the internal structure of the protection element shown as embodiment of this invention. It is sectional drawing explaining the internal structure of the protection element shown as embodiment of this invention. It is a figure explaining the circuit structure of the protection element shown as embodiment of this invention. 6 is a plan view illustrating an internal structure of a protection element manufactured as Example 6. FIG. It is a figure explaining the circuit structure of the conventional protection element. It is a figure explaining the circuit structure of the conventional protection element, and is a figure for demonstrating a mode that electricity supply was made | formed only from one electricity supply path | route. It is a figure explaining the circuit structure of the battery pack in which the conventional protection element is mounted.

  Hereinafter, specific embodiments to which the present invention is applied will be described in detail with reference to the drawings.

  This embodiment is a protective element that cuts off current by melting a low-melting point metal body (fuse element) in the event of an abnormality. In particular, this protective element has a structure in which a plurality of fuse elements are disposed between a plurality of electrodes serving as inputs of a current-carrying path formed on the base substrate, and by controlling the fusing time of each fuse element, When energization is performed from a specific energization path, heat generation of the heating resistor can be stopped after all the fuse elements are melted.

  First, prior to description of specific contents of the present invention, a basic configuration of a protection element to which the present invention is applied will be described.

  As shown in the plan view of FIG. 1 and the cross-sectional view of FIG. 2, the protection element includes a fuse element 12 that cuts off a current by fusing on a base substrate 11 of a predetermined size, and a fuse element 12 that generates heat when abnormal and generates heat. A heating resistor (heater) 13 for melting is disposed in close proximity.

  The base substrate 11 may be any material as long as it has an insulating property. For example, in addition to a substrate used for a printed wiring board such as a ceramic substrate or a glass epoxy substrate, a glass substrate or a resin substrate. Insulating metal substrates can be used. Among these, a ceramic substrate that is an insulating substrate having excellent heat resistance and good thermal conductivity is preferable.

  As the fuse element 12, various low melting point metal bodies conventionally used as a fuse material can be used. For example, alloys shown in Table 1 of Japanese Patent No. 3067011 can be used. Specifically, the low melting point metal forming the fuse element 12 includes SnSb alloy, BiSnPb alloy, BiPbSn alloy, BiPb alloy, BiSn alloy, SnPb alloy, SnAg alloy, PbIn alloy, ZnAl alloy, InSn alloy, PbAgSn alloy, etc. Can be mentioned. The shape of the fuse element 12 may be a flaky shape or a rod shape.

  Further, the heating resistor 13 is applied with a resistance paste made of a conductive material such as ruthenium oxide or carbon black and an inorganic binder such as water glass or an organic binder such as thermosetting resin, for example. It is formed by baking. Further, as the heating resistor 13, a thin film such as ruthenium oxide or carbon black may be formed through printing, plating, vapor deposition, sputtering, or may be formed by pasting or laminating these films.

  Further, in the protective element, on the surface of the base substrate 11, three fuse element electrodes 14 a, 14 b, 14 c electrically connected to the fuse element 12 and a heating resistor electrically connected to the heating resistor 13 are provided. A body electrode 15 is formed. The fuse element electrodes 14a, 14b, 14c and the heating resistor electrode 15 are arranged in a state of being insulated from the heating resistor 13 through an insulating film 16 such as glass.

  The fuse element electrodes 14a, 14b, and 14c are electrodes through which the melted fuse element 12 flows, respectively. There are no particular restrictions on the constituent materials of these fuse element electrodes 14a, 14b, and 14c, and it is possible to use a fuse element 12 in a molten state and a metal that has good wettability. For example, as the fuse element electrodes 14a, 14b, 14c, a single metal such as copper, or one having at least a surface formed of Ag, Ag-Pt, Ag-Pd, Au, or the like can be used.

  In the present invention, in order to control the fusing time of the fuse element 12, the wettability with the fuse element 12 may be changed between the fuse element electrodes 14a, 14b, and 14c as described later. . This will be described in detail later.

  On the other hand, it is not necessary to consider the wettability with the fuse element 12 in the molten state, but the heating resistor electrode 15 is normally formed together with the fuse element electrodes 14a, 14b, and 14c. It is made of the same material as the element electrodes 14a, 14b, 14c.

  Further, the fuse element electrodes 14a, 14b, and 14c and the heating resistor electrode 15 are connected to leads that serve as external terminals, although not particularly illustrated. This lead is made of a metal wire such as a flat processed wire or a round wire, and is attached to each of the fuse element electrodes 14a, 14b, 14c and the heating resistor electrode 15 by soldering or welding. Electrically connected. In the case of adopting such a form with leads in the protective element, it is possible to work without being aware of the mounting surface during the mounting work by making the positions of the leads symmetrical.

  Further, although not particularly illustrated, a sealing member made of flux or the like may be provided on the fuse element 12 in order to prevent surface oxidation. As the flux, any known flux such as rosin flux can be used, and the viscosity and the like are arbitrary.

  When the protective element is manufactured as a chip component, it is provided by being covered with a cap member made of, for example, 4,6-nylon or liquid crystal polymer.

  The circuit configuration of such a protection element can be expressed as shown in FIG. That is, the protective element is arranged so that two fuse elements 12a, 12b made of a low melting point metal body are bridged between the three fuse element electrodes 14a, 14b, 14c, and the fuse element electrode 14b at the center is arranged. And a heating resistor 13 is connected between the heating resistor electrode 15 and the heating resistor electrode 15. That is, in this protective element, two paths from either or both of the fuse element electrodes 14a and 14c on both sides to the center fuse element electrode 14b are energized paths.

  Therefore, in this protective element, when energization is performed from both of the two energization paths and the heating resistor 13 generates heat, the fuse element 12a between the fuse element electrodes 14a and 14b and the fuse element electrodes 14b and 14c are connected. The fuse element 12b is melted to cut off the energization to the device to be protected and the energization to the heating resistor 13 is also cut off.

  Now, in the present invention, by controlling the fusing time of each of the fuse elements 12a and 12b in such a protection element, all the two energization paths are energized from a specific energization path. After fusing the fuse elements 12a and 12b, the heat generation of the heating resistor 13 is stopped. In particular, the protective element is configured to be able to identify the “fuse element that is always blown at the end”, and at least when all the fuse elements are energized from the energization path to which the fuse element is connected. Is blown first.

  Here, the fusing time of each of the fuse elements 12a and 12b is configured such that the characteristics of the fuse elements 12a and 12b are different from each other, or the characteristics of the heating resistor 13 acting on the fuse elements 12a and 12b are changed. It can be controlled by changing the characteristics of the fuse element electrodes 14a, 14b, 14c which will flow when the fuse elements 12a, 12b are melted. Specifically, the fusing time of each of the fuse elements 12a and 12b can be controlled mainly by any one or combination of the following six methods.

  First, the first method is to provide a difference in physical shape such as a cross-sectional area (width and / or thickness) of each fuse element 12a, 12b. For example, in the protection element, the fusing time of the fuse element 12a can be made longer than the fusing time of the fuse element 12b by making the cross sectional area of the fuse element 12a larger than the cross sectional area of the fuse element 12b. In the protection element, the fusing time of each of the fuse elements 12a and 12b can be made different by making the fuse elements 12a and 12b different in shape.

  The second method is to provide a difference in the distance from each fuse element 12a, 12b to the heating resistor 13. For example, in the protective element, by making the distance from the fuse element 12a to the heating resistor 13 longer than the distance from the fuse element 12b to the heating resistor 13, the fusing time of the fuse element 12a is reduced. It can be longer than the fusing time. The distance from each of the fuse elements 12a and 12b to the heating resistor 13 does not mean only the interval on the plane, but the insulating film 16 serving as a heat transfer path using the heating resistor 13 as a heat source. It means a three-dimensional spatial distance such as an interval in the thickness direction. Accordingly, in the protection element, for example, the thickness of the insulating film 16 is changed between the fuse element electrodes 14a and 14b and between the fuse element electrodes 14b and 14b, thereby generating a heating resistor from each of the fuse elements 12a and 12b. A difference may be provided in the distance to the body 13, and one of the fuse elements 12a and 12b may be formed into a shape that floats from the insulating film 16 or the like. A difference in the distance to the heating resistor 13 may be provided.

  Furthermore, the third method is to provide a difference in wettability between the fuse elements 12a and 12b and the fuse element electrodes 14a, 14b, and 14c that flow when the fuse elements 12a and 12b are melted. is there. For example, in the protective element, the fuse element 12a and the fuse element 12a are melted rather than the wettability between the fuse element 12b and the fuse element electrodes 14b and 14c that flow when the fuse element 12b is melted. By reducing the wettability with the fuse element electrodes 14a and 14b that will flow in this case, the fusing time of the fuse element 12a can be made longer than the fusing time of the fuse element 12b. Such wettability can be changed by adjusting the metal composition of the fuse element electrodes 14a, 14b, 14c, and can also be changed by adjusting the metal composition of the fuse elements 12a, 12b. it can.

  Furthermore, the fourth method is to provide a difference in thermal properties such as the heat capacity, thermal conductivity, heat dissipation, and the like of portions adjacent to the fuse elements 12a, 12b or the heating resistor 13. For example, in the protection element, the fusing time of the fuse element 12a is made smaller than the fusing time of the fuse element 12b by making the heat capacity of the portion close to the fuse element 12b smaller than the heat capacity of the portion close to the fuse element 12a. Can be long. Such thermal properties include, for example, connecting another metal body such as a copper block near the electrode for one fuse element of the fuse elements 12a and 12b, or a metal layer on a part of the inner layer of the base substrate 11. Or by mixing a lot of glass material or the like in a part of the base substrate 11.

  The fifth method is to provide a difference in the melting points of the fuse elements 12a and 12b. For example, in the protective element, by selecting a low melting point metal body so that the melting point of the fuse element 12a is higher than the melting point of the fuse element 12b, the fusing time of the fuse element 12b can be reduced by the fusing time of the fuse element 12b. Can be longer.

  Furthermore, the sixth method is to provide a plurality of heating resistors and to provide a difference in the amount of heat generated by each of the heating resistors. For example, in the protective element, the heating resistance is set so that the heating value of the heating resistor disposed near the fuse element 12b is larger than the heating value of the heating resistor disposed near the fuse element 12a. By selecting the body, the fusing time of the fuse element 12a can be made longer than the fusing time of the fuse element 12b. The amount of heat generated by such a heating resistor can also be changed by adjusting the resistance value of the heating resistor.

  In the protection element, the fusing time of each of the fuse elements 12a and 12b can be controlled by any one or a combination of these six methods. In other words, the protective element is configured to be able to specify a fuse element having a long fusing time, that is, a “fuse element that is always blown last”, of the two fuse elements 12a and 12b. For this reason, in the protective element, all the other fuse elements can be blown first when energized from at least the energization path to which the “fuse element that is always blown last” is connected. This means that, if power is supplied from at least the current-carrying path to which the “fuse element that is always blown last” is connected, all current-carrying paths are cut off if the “fuse element that is to be blown last” is blown. Means that it is possible.

  Therefore, in the protective element, by connecting the “fuse element that is always blown last” to the specific fuse element electrode that is the input to the “energization path on the side that is always energized”, Even if there is no failure, the energization of the heating resistor 13 is cut off after the “fuse element that is always blown at the end” is blown, that is, after all the fuse elements 12a and 12b are surely blown. The heat generation can be stopped and the safety can be greatly improved. In particular, in the protective element, it is possible to flexibly control the fusing time of each of the fuse elements 12a and 12b by combining a plurality of methods instead of applying the above-described six methods alone. The effect is increased and the safety can be further improved.

  Such a protective element is preferably mounted on a battery pack that can be attached to and detached from an electronic device body such as a notebook personal computer. That is, in the battery pack, the cell side corresponds to “an energization path on the side where energization is always performed”. In this case, even if the battery pack is not energized from the charger side by removing the battery pack from the electronic device body by connecting the “fuse element that is always blown at the end” to the cell side. During operation, all fuse elements can be surely blown, and safety can be greatly improved.

  In the above-described embodiment, the case where there are two fuse elements 12a and 12b has been described. However, the present invention can be similarly applied even when there are three or more fuse elements. Thus, it goes without saying that the present invention can be modified as appropriate without departing from the spirit of the present invention.

[Example]
The inventor of the present application actually manufactured the protective element, conducted an energization test, and observed the presence or absence of fusing of the fuse element. The protective elements according to the configuration shown in FIGS. 1 to 3 are manufactured as comparative examples, and the protective elements according to the comparative examples are manufactured in accordance with the first to sixth methods. What changed the structure was produced as Example 1 thru | or Example 6. FIG. In the following, for convenience of explanation, the same members as those described above will be described with the same reference numerals.

(Comparative example)
An alumina ceramic substrate having a width of 3 mm, a length of 5 mm, and a thickness of 0.5 mm is used as a base substrate 11, on which fuse elements 12 a and 12 b, a heating resistor 13, fuse element electrodes 14 a, 14 b and 14 c, and a heating resistor are used. An electrode 15 and an insulating film 16 were formed.

  As the fuse elements 12a and 12b, low melting point metal foils of width 1 mm × length 4 mm × thickness 0.1 mm made of SnSb alloy (Sn: Sb = 95: 5, liquidus point 240 ° C.) were used. The heating resistor 13 was formed by printing a ruthenium oxide-based heating resistor paste (trade name DP1900; manufactured by DuPont) on the base substrate 11 and baking it at 850 ° C. for 30 minutes. The heating resistor 13 had a pattern resistance value of 5Ω.

  Further, the fuse element electrodes 14a, 14b, and 14c were formed by printing an Ag-Pt paste (trade name: 5164N; manufactured by DuPont) on the base substrate 11 and firing at 850 ° C. for 30 minutes. Furthermore, the heating resistor electrode 15 was formed by printing an Ag—Pd paste (trade name 6177T; manufactured by DuPont) on the base substrate 11 and baking it at 850 ° C. for 30 minutes. The insulating film 16 was formed by printing a glass-based inorganic paste on the base substrate 11.

  Ten such protective elements were fabricated, and energized only from the fuse element electrode 14a side, and the presence or absence of fusing of the fuse elements 12a and 12b was observed. As a result, in 5 out of 10 protective elements, before the fuse element 12b between the fuse element electrodes 14b and 14c is blown, the fuse element 12a between the fuse element electrodes 14a and 14b is blown and the fuse element 12b is blown. The energization (heat generation of the heating resistor 13) was stopped without being melted. That is, in the protection element manufactured as a comparative example, the fuse element 12b that was not energized remained unfused with a probability of 50%, and all the energization paths were not interrupted.

Example 1
Example 1 is an example in which a protection element was manufactured by providing a difference in the cross-sectional areas of the fuse elements 12a and 12b according to the first method described above. That is, in the first embodiment, the width of the fuse element 12b between the fuse element electrodes 14b and 14c is formed to 0.7 mm, while the width of the fuse element 12a between the fuse element electrodes 14a and 14b is formed to 1 mm. Then, a protective element was produced. Other configurations are the same as those of the comparative example.

  Ten such protective elements were fabricated, and energized only from the fuse element electrode 14a side, and the presence or absence of fusing of the fuse elements 12a and 12b was observed. As a result, in all the 10 protection elements evaluated, the fuse element 12b between the fuse element electrodes 14b and 14c is blown first, and then the fuse element 12a between the fuse element electrodes 14a and 14b is blown and energized. Stopped. In addition, as a supplement to Example 1, a protective element in which the width of the fuse element 12b between the fuse element electrodes 14b and 14c was formed to 0.8 mm was produced, and the same energization was performed. In the protective element, the fuse element 12b was not melted. That is, it was confirmed from Example 1 that it is effective to provide a difference in the cross-sectional areas of the fuse elements 12a and 12b, and that the larger the difference, the greater the effect.

(Example 2)
Example 2 is an example in which a protection element was manufactured by providing a difference in distance from each fuse element 12a, 12b to the heating resistor 13 in accordance with the second method described above. That is, in the second embodiment, the position of the heating resistor 13 disposed at the approximate center position in the arrangement direction of the fuse element electrodes 14a, 14b, 14c is shifted by 0.1 mm toward the fuse element electrode 14c. Then, a protective element was produced. Other configurations are the same as those of the comparative example.

  Ten such protective elements were fabricated, and energized only from the fuse element electrode 14a side, and the presence or absence of fusing of the fuse elements 12a and 12b was observed. As a result, in all the 10 protection elements evaluated, the fuse element 12b between the fuse element electrodes 14b and 14c is blown first, and then the fuse element 12a between the fuse element electrodes 14a and 14b is blown and energized. Stopped. In addition, as a supplement to Example 2, a protective element in which the shift amount of the heating resistor 13 was reduced to 0.05 mm was manufactured and the same energization was performed. As a result, in three of the ten protective elements, the fuse element 12b Became unfused. That is, from Example 2, it was effective to provide a difference in the distance from the fuse elements 12a, 12b to the heating resistor 13, and it was confirmed that the effect was greater as the difference was larger.

(Example 3)
Example 3 is an example in which a protection element was manufactured by providing a difference in wettability between the fuse elements 12a, 12b and the fuse element electrodes 14a, 14b, 14c according to the third method described above. That is, in Example 3, gold was plated on the entire surface area of the fuse element electrode 14c and the surface half area on the fuse element electrode 14c side of the fuse element electrode 14b to produce a protection element. Other configurations are the same as those of the comparative example.

  Ten such protective elements were fabricated, and energized only from the fuse element electrode 14a side, and the presence or absence of fusing of the fuse elements 12a and 12b was observed. As a result, in all the 10 protection elements evaluated, the fuse element 12b between the fuse element electrodes 14b and 14c is blown first, and then the fuse element 12a between the fuse element electrodes 14a and 14b is blown and energized. Stopped. That is, from Example 3, it was confirmed that it was effective to provide a difference in wettability between the fuse elements 12a and 12b and the fuse element electrodes 14a, 14b, and 14c.

Example 4
Example 4 is an example in which a protection element was manufactured by providing a difference in the thermal properties of portions close to the fuse elements 12a, 12b or the heating resistor 13 in accordance with the fourth method described above. That is, in this Example 4, a copper block having a width of 0.5 mm, a length of 0.5 mm and a thickness of 0.5 mm was soldered and connected in the vicinity of the fuse element electrode 14a to produce a protective element. Other configurations are the same as those of the comparative example.

  Ten such protective elements were fabricated, and energized only from the fuse element electrode 14a side, and the presence or absence of fusing of the fuse elements 12a and 12b was observed. As a result, in all the 10 protection elements evaluated, the fuse element 12b between the fuse element electrodes 14b and 14c is blown first, and then the fuse element 12a between the fuse element electrodes 14a and 14b is blown and energized. Stopped. That is, it was confirmed from Example 4 that it is effective to provide a difference in the thermal properties of the portions adjacent to the fuse elements 12a, 12b or the heating resistor 13.

(Example 5)
Example 5 is an example in which a protection element was produced by providing a difference in the melting points of the fuse elements 12a and 12b according to the fifth method described above. That is, in the fifth embodiment, the fuse element 12b between the fuse element electrodes 14b and 14c is replaced with a SnAg alloy (Sn: Ag = 96.5: 3.5, liquid phase point 221 ° C.), and a protection element is produced. did. Other configurations are the same as those of the comparative example.

  Ten such protective elements were fabricated, and energized only from the fuse element electrode 14a side, and the presence or absence of fusing of the fuse elements 12a and 12b was observed. As a result, in all the 10 protection elements evaluated, the fuse element 12b between the fuse element electrodes 14b and 14c is blown first, and then the fuse element 12a between the fuse element electrodes 14a and 14b is blown and energized. Stopped. That is, from Example 5, it was confirmed that it was effective to provide a difference in the melting points of the fuse elements 12a and 12b.

(Example 6)
Example 6 is an example in which a plurality of heating resistors are arranged according to the above-described sixth method, and a protection element is manufactured by providing a difference in the amount of heat generated by each of the heating resistors. That is, in Example 6, as shown in FIG. 4, two heating resistors 13a and 13b having different resistance values are arranged in series between the fuse element electrodes 14a and 14b and between the fuse element electrodes 14b and 14c. And a protective element was produced. The resistance value of the heating resistor 13a disposed near the fuse element 12a was 2Ω, and the resistance value of the heating resistor 13b disposed near the fuse element 12b was 3Ω. Other configurations are the same as those of the comparative example.

  Ten such protective elements were prepared, and current was supplied only from the fuse element electrode 14a side with a constant current of 1A, and the presence or absence of fusing of the fuse elements 12a and 12b was observed. As a result, in all the 10 protection elements evaluated, the fuse element 12b between the fuse element electrodes 14b and 14c is blown first, and then the fuse element 12a between the fuse element electrodes 14a and 14b is blown and energized. Stopped. In addition, as a supplement to Example 6, a protective element having a resistance value of the heating resistor 13a between the fuse element electrodes 14a and 14b increased to 2.5Ω was manufactured and the same energization was performed. In each of the protection elements, the fuse element 12b was not melted. That is, it was confirmed from Example 6 that it is effective to dispose a plurality of heating resistors having different heat generation amounts, and that the larger the difference in the heat generation amount, the greater the effect.

11 Base substrate 12, 12a, 12b Fuse element 13, 13a, 13b Heating resistor 14a, 14b, 14c Fuse element electrode 15 Heating resistor electrode 16 Insulating film

Claims (9)

In a protective element in which a plurality of fuse elements are disposed between a plurality of electrodes serving as inputs of a current-carrying path, and current is cut off by fusing of the fuse element due to heat generated by the energized heating element,
When there is energization from a specific energization path to which a specific fuse element is connected among the plurality of fuse elements, the plurality of fuse elements are blown before the specific fuse element. It is configured to control the fusing time of the fuse element,
The specific electrode to which the specific fuse element is connected is an electrode serving as an input of a current-carrying path that is always energized among the plurality of electrodes,
There is a difference in wettability between each of the plurality of fuse elements and each of the plurality of electrodes so that the fusing time of the specific fuse element is longer than the fusing time of the other fuse elements. A protective element. Specific that will flow when the specific fuse element and the specific fuse element are melted, rather than the wettability of the other fuse element with the other electrode that will flow when the other fuse element is melted The protective element according to claim 1, wherein the metal composition of the plurality of fuse elements or the plurality of electrodes or both of them is adjusted so as to reduce wettability with the electrodes. In a protective element in which a plurality of fuse elements are disposed between a plurality of electrodes serving as inputs of a current-carrying path, and current is cut off by fusing of the fuse element due to heat generated by the energized heating element,
When there is energization from a specific energization path to which a specific fuse element is connected among the plurality of fuse elements, the plurality of fuse elements are blown before the specific fuse element. It is configured to control the fusing time of the fuse element,
The specific electrode to which the specific fuse element is connected is an electrode serving as an input of a current-carrying path that is always energized among the plurality of electrodes,
There is a difference in thermal properties of each of the plurality of fuse elements or in the vicinity of the heating element so that the fusing time of the specific fuse element is longer than the fusing time of other fuse elements. Protective element. The protection element according to claim 3, wherein the thermal property is a thermal capacity, thermal conductivity, or heat dissipation of each of the plurality of fuse elements or a portion adjacent to the heating element. In a protective element in which a plurality of fuse elements are disposed between a plurality of electrodes serving as inputs of a current-carrying path, and current is cut off by fusing of the fuse element due to heat generated by the energized heating element,
When there is energization from a specific energization path to which a specific fuse element is connected among the plurality of fuse elements, the plurality of fuse elements are blown before the specific fuse element. It is configured to control the fusing time of the fuse element,
The specific electrode to which the specific fuse element is connected is an electrode serving as an input of a current-carrying path that is always energized among the plurality of electrodes,
The protection element, wherein the melting points of the plurality of fuse elements are different from each other so that the fusing time of the specific fuse element is longer than the fusing time of the other fuse elements. The protection element according to claim 5, wherein a melting point of the specific fuse element is higher than a melting point of another fuse element. In a protective element in which a plurality of fuse elements are disposed between a plurality of electrodes serving as inputs of a current-carrying path, and current is cut off by fusing of the fuse element due to heat generated by the energized heating element,
When there is energization from a specific energization path to which a specific fuse element is connected among the plurality of fuse elements, the plurality of fuse elements are blown before the specific fuse element. It is configured to control the fusing time of the fuse element,
The specific electrode to which the specific fuse element is connected is an electrode serving as an input of a current-carrying path that is always energized among the plurality of electrodes,
A plurality of the heating elements are arranged,
A protective element characterized in that there is a difference in the amount of heat generated by each of the plurality of heating elements. The resistance value of a specific heating resistor arranged near the specific fuse element is smaller than the resistance value of another heating resistor arranged near the other fuse element. The protective element according to claim 7, characterized in that: It can be attached to and detached from the electronic device body,
9. A battery pack comprising: the protection element according to claim 1; and the specific fuse element connected to a cell side of the battery pack.