Short-circuit element and a circuit using the same

• US 9,953,793 B2
• Filed: 08/05/2015
• Issued: 04/24/2018
• Est. Priority Date: 02/05/2013
• Status: Active Grant

• Current Assignee: Dexerials Corporation
• Original Assignee: Dexerials Corporation
• Inventors: Yoneda, Yoshihiro
• Primary Examiner(s): Tran, Thienvu
• Assistant Examiner(s): Comber, Kevin J
• Application Number:
  US14/819,328
• Publication Number:
  US 20160005562A1
• Time in Patent Office: 993 Days
• Field of Search: 361 54
• CPC Class Codes: H01H 2231/026 Car
• CPC Class Codes: H01H 37/761 with a fusible element forming part of the switched circuit H01H37/767 takes precedence
• CPC Class Codes: H01H 37/767 Normally open
• CPC Class Codes: H01H 61/02 wherein the thermally-sensitive member is heated indirectly, e.g. resistively, inductively
• CPC Class Codes: H01H 85/0056 Heat conducting or heat absorbing means associated with the fusible member, e.g. for providing time delay
• CPC Class Codes: H01H 85/0241 Structural association of a fuse and another component or apparatus switches with built-in fuses H01H9/10, spark-gap arresters H01H85/44, transformers and inductances H01F27/402, capacitors H01G2/14, lamps H01K1/66, semiconductors H01L23/5256 or H01L23/62
• CPC Class Codes: H01H 85/055 Fusible members
• CPC Class Codes: H01M 10/425 Structural combination with electronic components, e.g. electronic circuits integrated to the outside of the casing printed circuits H05K1/00
• CPC Class Codes: H01M 10/441 for several batteries or cells simultaneously or sequentially
• CPC Class Codes: H01M 10/482 for several batteries or cells simultaneously or sequentially
• CPC Class Codes: H01M 2200/10 Temperature sensitive devices
• CPC Class Codes: H01M 2200/103 Fuse
• CPC Class Codes: H01M 2200/108 Normal resistors
• CPC Class Codes: H01M 50/581 in response to temperature
• CPC Class Codes: Y02E 60/10 Energy storage using batteries

Abstract

A bypass avoiding only abnormal cells or abnormal electronic components in an electronic appliance having a plurality of battery cells or electronic components is formed to decrease resistance while keeping functionality. An insulating substrate 2; a heat-generating resistor 3 arranged on the insulating substrate 2; a first and a second electrodes 4, 5 arranged adjacently to each other on the insulating substrate 2; a third electrode 6 arranged adjacently to the first electrode 4 and electrically connected to the heat-generating resistor; and a first meltable conductor 8 arranged between the first and third electrodes 4, 6 to constitute a current path capable of being blown by a heat generated by the heat-generating resistor 3 are provided. The first meltable conductor 8 melted by heat from the heat-generating resistor 3 gathers on the first and second electrodes 4, 5 to short-circuit them.

Claims

1. A short-circuit element comprising:

an insulating substrate;

a heat-generating resistor arranged on the insulating substrate;

a first and a second electrodes arranged adjacently to each other on the insulating substrate;

a third electrode arranged adjacently to the first electrode on the insulating substrate and electrically connected to the heat-generating resistor; and

a first meltable conductor arranged between the first and third electrodes to constitute a current path capable of being blown by a heat generated by the heat-generating resistor,

wherein the first meltable conductor is melted by the heat from the heat-generating resistor and gathers on the first and second electrodes to short-circuit the first and second electrodes.

2. The short-circuit element according to claim 1 further comprising a second meltable conductor arranged on the second electrode,

wherein the first and second meltable conductors are melted by the heat from the heat-generating resistor and gather on the first and second electrodes to short-circuit the first and second electrodes.

3. The short-circuit element according to claim 2,

wherein the second meltable conductor is narrower than the first meltable conductor.

4. The short-circuit element according to claim 2 further comprising an insulating layer laminated on the insulating substrate,

wherein the first to third electrodes are arranged on the insulating layer, and

wherein the heat-generating resistor is disposed within the insulating layer or between the insulating layer and the insulating substrate.

5. The short-circuit element according to claim 2, wherein the heat-generating resistor is disposed within the insulating substrate.

6. The short-circuit element according to claim 2, wherein the heat-generating resistor is disposed on a surface of the insulating substrate opposite to an electrode-forming surface.

7. The short-circuit element according to claim 2, wherein the heat-generating resistor is disposed on an electrode-forming surface of the insulating substrate.

8. The short-circuit element according to claim 2 further comprising:

a second meltable conductor arranged on the second electrode,

wherein the heat-generating resistor overlaps the first meltable conductor and the second meltable conductor, and the overlap area of the second meltable conductor is larger than that of the first meltable conductor.

9. The short-circuit element according to claim 2, wherein surfaces of the first electrode and the second electrode are coated with one of Ni/Au plating, Ni/Pd plating and Ni/Pd/Au plating.

10. The short-circuit element according to claim 2 further comprising:

a fourth electrode arranged adjacently to the second electrode on the insulating substrate; and

a second meltable conductor arranged between the second and fourth electrodes to constitute a current path capable of being blown by a heat generated by the heat-generating resistor,

wherein the first electrode has an area wider than that of the third electrode, and the second electrode has an area wider than that of the fourth electrode.

11. The short-circuit element according to claim 2 further comprising:

a covering member arranged on the insulating substrate for internal protection; and

a covering member electrode arranged on an inner surface of the covering member,

wherein the covering member electrode is arranged at a position which overlaps the first electrode and the second electrode.

12. The short-circuit element according to claim 2 further comprising a protective resistor arranged on the insulating substrate and connected to one of the first electrode and the second electrode.

13. The short-circuit element according to claim 2 further comprising:

a second meltable conductor arranged on the second electrode,

wherein the first and second meltable conductors are a Pb free solder consisting essentially of Sn.

14. The short-circuit element according to claim 2 further comprising:

a second meltable conductor arranged on the second electrode,

wherein the first and second meltable conductors contain a low melting point metal and a high melting point metal, and

wherein the low melting point metal is melted by a heat generated by the heat-generating resistor and erodes the high melting point metal.

15. The short-circuit element according to claim 14,

wherein the low melting point metal is a solder, and

wherein the high melting point metal is Ag, Cu or an alloy consisting essentially of Ag or Cu.

16. The short-circuit element according to claim 14, wherein the first and second meltable conductors have a coated structure in which the low melting point metal constitutes an inner layer and the high melting point metal constitutes an outer layer.

17. The short-circuit element according to claim 14, wherein the first and second meltable conductors have a coated structure in which the high melting point metal constitutes an inner layer and the low melting point metal constitutes an outer layer.

18. The short-circuit element according to claim 14, wherein the first and second meltable conductors have a laminated structure in which the low melting point metal and the high melting point metal are laminated.

19. The short-circuit element according to claim 14, wherein the first and second meltable conductors have a multi-layered structure having four or more layers in which the low melting point metal and the high melting point metal are alternately laminated.

20. The short-circuit element according to claim 14, wherein the first and second meltable conductors have a stripe-shaped structure in which the high melting point metal partially overlaps a surface of the low melting point metal.

21. The short-circuit element according to claim 14, wherein the first and second meltable conductors are constituted of a high melting point metal having a plurality of openings and a low melting point metal inserted in the openings.

22. The short-circuit element according to claim 14, wherein, in the first and second meltable conductors, the volume of the low melting point metal is larger than that of the high melting point metal.

23. The short-circuit element according to claim 2,

wherein a first external connecting electrode continuous with the first electrode on the same surface as the meltable conductor, one or more first external connecting terminals provided on the first external connecting electrode, a second external connecting electrode continuous with the second electrode, and one or more second external connecting terminals provided on the second external connecting electrode are formed on the insulating substrate, and

wherein a combined resistance of the first external connecting terminal and the second external connecting terminal is lower than a conduction resistance between the first and second external connecting electrodes when the first electrode and the second electrode are short-circuited.

24. The short-circuit element according to claim 23, wherein the external connecting terminal is a metal bump made of a lead-free solder consisting essentially of tin.

25. The short-circuit element according to claim 23, wherein the external connecting terminal is one of a metal bump and a metal post.

26. The short-circuit element according to claim 25, wherein, in the metal bump or metal post, a low melting point metal layer is formed on a high melting point metal surface.

27. The short-circuit element according to claim 26, wherein the high melting point metal consists essentially of copper or silver, and the low melting point metal is a lead-free solder consisting essentially of tin.

28. The short-circuit element according to claim 1 further comprising:

a fourth electrode arranged adjacently to the second electrode on the insulating substrate; and

a second meltable conductor arranged between the second and fourth electrodes to constitute a current path capable of being blown by a heat generated by the heat-generating resistor,

wherein the first and second meltable conductors are melted by the heat from the heat-generating resistor and gather on the first and second electrodes to short-circuit the first and second electrodes.

29. The short-circuit element according to claim 28 further comprising an insulating layer laminated on the insulating substrate,

wherein the first to third electrodes are arranged on the insulating layer, and

wherein the heat-generating resistor is disposed within the insulating layer or between the insulating layer and the insulating substrate.

30. The short-circuit element according to claim 28, wherein the heat-generating resistor is disposed within the insulating substrate.

31. The short-circuit element according to claim 28, wherein the heat-generating resistor is disposed on a surface of the insulating substrate opposite to an electrode-forming surface.

32. The short-circuit element according to claim 28, wherein the heat-generating resistor is disposed on an electrode-forming surface of the insulating substrate.

33. The short-circuit element according to claim 28 further comprising:

a second meltable conductor arranged on the second electrode,

wherein the heat-generating resistor overlaps the first meltable conductor and the second meltable conductor, and the overlap area of the second meltable conductor is larger than that of the first meltable conductor.

34. The short-circuit element according to claim 28,

wherein the second meltable conductor is narrower than the first meltable conductor.

35. The short-circuit element according to claim 28, wherein surfaces of the first electrode and the second electrode are coated with one of Ni/Au plating, Ni/Pd plating and Ni/Pd/Au plating.

36. The short-circuit element according to claim 28 further comprising:

a fourth electrode arranged adjacently to the second electrode on the insulating substrate; and

a second meltable conductor arranged between the second and fourth electrodes to constitute a current path capable of being blown by a heat generated by the heat-generating resistor,

wherein the first electrode has an area wider than that of the third electrode, and the second electrode has an area wider than that of the fourth electrode.

37. The short-circuit element according to claim 28 further comprising:

a covering member arranged on the insulating substrate for internal protection; and

a covering member electrode arranged on an inner surface of the covering member,

wherein the covering member electrode is arranged at a position which overlaps the first electrode and the second electrode.

38. The short-circuit element according to claim 28 further comprising a protective resistor arranged on the insulating substrate and connected to one of the first electrode and the second electrode.

39. The short-circuit element according to claim 28 further comprising:

a second meltable conductor arranged on the second electrode,

wherein the first and second meltable conductors are a Pb free solder consisting essentially of Sn.

40. The short-circuit element according to claim 28 further comprising:

a second meltable conductor arranged on the second electrode,

wherein the first and second meltable conductors contain a low melting point metal and a high melting point metal, and

wherein the low melting point metal is melted by a heat generated by the heat-generating resistor and erodes the high melting point metal.

41. The short-circuit element according to claim 40,

wherein the low melting point metal is a solder, and

wherein the high melting point metal is Ag, Cu or an alloy consisting essentially of Ag or Cu.

42. The short-circuit element according to claim 40, wherein the first and second meltable conductors have a coated structure in which the low melting point metal constitutes an inner layer and the high melting point metal constitutes an outer layer.

43. The short-circuit element according to claim 40, wherein the first and second meltable conductors have a coated structure in which the high melting point metal constitutes an inner layer and the low melting point metal constitutes an outer layer.

44. The short-circuit element according to claim 40, wherein the first and second meltable conductors have a laminated structure in which the low melting point metal and the high melting point metal are laminated.

45. The short-circuit element according to claim 40, wherein the first and second meltable conductors have a multi-layered structure having four or more layers in which the low melting point metal and the high melting point metal are alternately laminated.

46. The short-circuit element according to claim 40, wherein the first and second meltable conductors have a stripe-shaped structure in which the high melting point metal partially overlaps a surface of the low melting point metal.

47. The short-circuit element according to claim 40, wherein the first and second meltable conductors are constituted of a high melting point metal having a plurality of openings and a low melting point metal inserted in the openings.

48. The short-circuit element according to claim 40, wherein, in the first and second meltable conductors, the volume of the low melting point metal is larger than that of the high melting point metal.

49. The short-circuit element according to claim 28,

wherein a first external connecting electrode continuous with the first electrode on the same surface as the meltable conductor, one or more first external connecting terminals provided on the first external connecting electrode, a second external connecting electrode continuous with the second electrode, and one or more second external connecting terminals provided on the second external connecting electrode are formed on the insulating substrate, and

wherein a combined resistance of the first external connecting terminal and the second external connecting terminal is lower than a conduction resistance between the first and second external connecting electrodes when the first electrode and the second electrode are short-circuited.

50. The short-circuit element according to claim 49, wherein the external connecting terminal is a metal bump made of a lead-free solder consisting essentially of tin.

51. The short-circuit element according to claim 49, wherein the external connecting terminal is one of a metal bump and a metal post.

52. The short-circuit element according to claim 51, wherein, in the metal bump or metal post, a low melting point metal layer is formed on a high melting point metal surface.

53. The short-circuit element according to claim 52, wherein the high melting point metal consists essentially of copper or silver, and the low melting point metal is a lead-free solder consisting essentially of tin.

54. The short-circuit element according to claim 1 further comprising an insulating layer laminated on the insulating substrate,

wherein the first to third electrodes are arranged on the insulating layer, and

wherein the heat-generating resistor is disposed within the insulating layer or between the insulating layer and the insulating substrate.

55. The short-circuit element according to claim 1, wherein the heat-generating resistor is disposed within the insulating substrate.

56. The short-circuit element according to claim 1, wherein the heat-generating resistor is disposed on a surface of the insulating substrate opposite to an electrode-forming surface.

57. The short-circuit element according to claim 1, wherein the heat-generating resistor is disposed on an electrode-forming surface of the insulating substrate.

58. The short-circuit element according to claim 1 further comprising:

a second meltable conductor arranged on the second electrode,

wherein the heat-generating resistor overlaps the first meltable conductor and the second meltable conductor, and the overlap area of the second meltable conductor is larger than that of the first meltable conductor.

59. The short-circuit element according to claim 1, wherein surfaces of the first electrode and the second electrode are coated with one of Ni/Au plating, Ni/Pd plating and Ni/Pd/Au plating.

60. The short-circuit element according to claim 1 further comprising:

a fourth electrode arranged adjacently to the second electrode on the insulating substrate; and

a second meltable conductor arranged between the second and fourth electrodes to constitute a current path capable of being blown by a heat generated by the heat-generating resistor,

wherein the first electrode has an area wider than that of the third electrode, and the second electrode has an area wider than that of the fourth electrode.

61. The short-circuit element according to claim 1 further comprising:

a covering member arranged on the insulating substrate for internal protection; and

a covering member electrode arranged on an inner surface of the covering member,

wherein the covering member electrode is arranged at a position which overlaps the first electrode and the second electrode.

62. The short-circuit element according to claim 1 further comprising a protective resistor arranged on the insulating substrate and connected to one of the first electrode and the second electrode.

63. The short-circuit element according to claim 1 further comprising:

a second meltable conductor arranged on the second electrode,

wherein the first and second meltable conductors are a Pb free solder consisting essentially of Sn.

64. The short-circuit element according to claim 1 further comprising:

a second meltable conductor arranged on the second electrode,

wherein the first and second meltable conductors contain a low melting point metal and a high melting point metal, and

wherein the low melting point metal is melted by a heat generated by the heat-generating resistor and erodes the high melting point metal.

65. The short-circuit element according to claim 64,

wherein the low melting point metal is a solder, and

wherein the high melting point metal is Ag, Cu or an alloy consisting essentially of Ag or Cu.

66. The short-circuit element according to claim 64, wherein the first and second meltable conductors have a coated structure in which the low melting point metal constitutes an inner layer and the high melting point metal constitutes an outer layer.

67. The short-circuit element according to claim 64, wherein the first and second meltable conductors have a coated structure in which the high melting point metal constitutes an inner layer and the low melting point metal constitutes an outer layer.

68. The short-circuit element according to claim 64, wherein the first and second meltable conductors have a laminated structure in which the low melting point metal and the high melting point metal are laminated.

69. The short-circuit element according to claim 64, wherein the first and second meltable conductors have a multi-layered structure having four or more layers in which the low melting point metal and the high melting point metal are alternately laminated.

70. The short-circuit element according to claim 64, wherein the first and second meltable conductors have a stripe-shaped structure in which the high melting point metal partially overlaps a surface of the low melting point metal.

71. The short-circuit element according to claim 64, wherein the first and second meltable conductors are constituted of a high melting point metal having a plurality of openings and a low melting point metal inserted in the openings.

72. The short-circuit element according to claim 64, wherein, in the first and second meltable conductors, the volume of the low melting point metal is larger than that of the high melting point metal.

73. The short-circuit element according to claim 1,

wherein a first external connecting electrode continuous with the first electrode on the same surface as the meltable conductor, one or more first external connecting terminals provided on the first external connecting electrode, a second external connecting electrode continuous with the second electrode, and one or more second external connecting terminals provided on the second external connecting electrode are formed on the insulating substrate, and

wherein a combined resistance of the first external connecting terminal and the second external connecting terminal is lower than a conduction resistance between the first and second external connecting electrodes when the first electrode and the second electrode are short-circuited.

74. The short-circuit element according to claim 73, wherein the external connecting terminal is a metal bump made of a lead-free solder consisting essentially of tin.

75. The short-circuit element according to claim 73, wherein the external connecting terminal is one of a metal bump and a metal post.

76. The short-circuit element according to claim 75, wherein, in the metal bump or metal post, a low melting point metal layer is formed on a high melting point metal surface.

77. The short-circuit element according to claim 76, wherein the high melting point metal consists essentially of copper or silver, and the low melting point metal is a lead-free solder consisting essentially of tin.

78. A short-circuit element circuit comprising:

a fuse;

a heat-generating resistor connected to one terminal of the fuse; and

a switch connected to another terminal of the fuse to which the heat-generating resistor is not connected,

wherein the switch is short-circuited in conjunction with blowout of the fuse.

79. A compensation circuit comprising:

a short-circuit element having a fuse, a heat-generating resistor connected to one terminal of the fuse, and a switch connected to another terminal of the fuse to which the heat-generating resistor is not connected, the switch being short-circuited in conjunction with blowout of the fuse; and

an electronic component,

wherein both terminals of the switch are connected to the electronic component in parallel,

wherein an open terminal of the heat-generating resistor is connected to the terminal of the switch to which the fuse is not connected, and

wherein, in an abnormal situation of the electronic component, the fuse melts to short-circuit the switch so as to form a bypass current path bypassing the electronic component.

80. The compensation circuit according to claim 79, wherein the electronic component is a light emitting diode which is electrically disconnected in the case of an abnormal situation.

81. The compensation circuit according to claim 80, wherein a protective resistor having a resistance corresponding to an internal resistance of the electronic component is connected in the bypass current path.

82. The compensation circuit according to claim 79, wherein a protective resistor having a resistance corresponding to an internal resistance of the electronic component is connected in the bypass current path.

83. A compensation circuit comprising:

a short-circuit element having a fuse, a heat-generating resistor connected to one terminal of the fuse, and a switch connected to another terminal of the fuse to which the heat-generating resistor is not connected, the switch being short-circuited in conjunction with melting of the fuse; and

an electronic component;

a protective element connected in a current path of the electronic component which interrupts current flowing to the electronic component in the case of an electric signal;

a protective component which detects an abnormality of the electronic component and outputs an abnormal signal; and

a controlling element which operates in accordance with the abnormal signal from the protective component,

wherein both terminals of the electronic component and the protective element are connected to both terminals of the switch in parallel,

wherein an open terminal of the heat-generating resistor and an input terminal for the electric signal of the controlling element are connected to the protective element, and

wherein, in an abnormal situation of the electronic component, the controlling element operates in accordance with an abnormal signal from the protective component to disconnect the current path of the electronic component with the protective element and to short-circuit the switch in conjunction with melting of the fuse to form a bypass current path.

84. The compensation circuit according to claim 83, wherein the electronic component is a battery cell having a risk of electrical short-circuit or thermal runaway occurring in an abnormal situation.

85. The compensation circuit according to claim 83, wherein a protective resistor having a resistance corresponding to an internal resistance of the electronic component is connected in the bypass current path.

86. The compensation circuit according to claim 85,

wherein the controlling element comprises a first controlling element connected to an open terminal of the heat-generating resistor and a second controlling element connected to an electric signal input terminal of the protective element, and

wherein the protective component, and the first and second controlling element are controlled such that the protective element disconnects the current path and then the short-circuit element forms a bypass current path.

87. The compensation circuit according to claim 83,

wherein the controlling element comprises a first controlling element connected to an open terminal of the heat-generating resistor and a second controlling element connected to an electric signal input terminal of the protective element, and

wherein the protective component, and the first and second controlling element are controlled such that the protective element disconnects the current path and then the short-circuit element forms a bypass current path.

88. A short-circuit element circuit comprising:

a fuse;

a heat-generating resistor connected to one terminal of the fuse;

a switch connected to another terminal of the fuse to which the heat-generating resistor is not connected; and

a protective resistor connected to at least one terminal of the switch,

wherein the switch is short-circuited in conjunction with blowout of the fuse.

89. A compensation circuit comprising:

a short-circuit element having a fuse, a heat-generating resistor connected to one terminal of the fuse, a switch connected to another terminal of the fuse to which the heat-generating resistor is not connected, and a protective resistor connected to at least one terminal of the switch to which the fuse is not connected, the switch being short-circuited in conjunction with melting of the fuse; and

an electronic component,

wherein the terminal connected to the switch and the fuse and an open terminal of the protective resistor, are connected to the electronic component in parallel,

wherein the heat-generating resistor is connected to the protective resistor, and

wherein, in an abnormal situation of the electronic component, the fuse melts to turn on the switch so as to form a bypass current path.

90. The compensation circuit according to claim 89, wherein the electronic component is a light emitting diode which is electrically disconnected in the case of an abnormal situation.

91. A compensation circuit comprising:

a short-circuit element having a fuse, a heat-generating resistor connected to one terminal of the fuse, a switch connected to another terminal of the fuse to which the heat-generating resistor is not connected, and a protective resistor connected to at least one terminal of the switch to which the fuse is not connected, the switch being short-circuited in conjunction with melting of the fuse;

an electronic component,

a protective element connected in a current path of the electronic component, which disconnects the electrical connection to the electronic component in the case of an electronic signal;

a protective component which detects an abnormality of the electronic component and outputs an abnormal signal; and

a controlling element which operates in accordance with the abnormal signal from the protective component,

wherein both terminals of the electronic component and the protective element are connected to the terminal of the switch connected to the fuse and the protective resistor in parallel,

wherein an open terminal of the heat-generating resistor and an input terminal for the electric signal of the controlling element are connected to the protective element, and

wherein, in an abnormal situation of the electronic component, the controlling element operates in accordance with an abnormal signal from the protective component to disconnect the current path of the electronic component with the protective element and to short-circuit the switch in conjunction with melting of the fuse to form a bypass current path.

92. The compensation circuit according to claim 91, wherein the electronic component is a battery cell a battery cell having a risk of electrical short-circuit or thermal runaway occurring in an abnormal situation.

93. The compensation circuit according to claim 92,

wherein the controlling element comprises a first controlling element connected to an open terminal of the heat-generating resistor and a second controlling element connected to an electric signal input terminal of the protective element, and

wherein the protective component, and the first and second controlling elements are controlled such that the protective element disconnects the current path and then the short-circuit element forms a bypass current path.

94. The compensation circuit according to claim 91,

wherein the controlling element comprises a first controlling element connected to an open terminal of the heat-generating resistor and a second controlling element connected to an electric signal input terminal of the protective element, and

wherein the protective component, and the first and second controlling elements are controlled such that the protective element disconnects the current path and then the short-circuit element forms a bypass current path.

95. A mounting member in which a short-circuit element is mounted onto a mounting target, the short-circuit element comprising:

an insulating substrate;

a heat-generating resistor arranged on the insulating substrate;

a first and a second electrodes arranged adjacently to each other on the insulating substrate;

a third electrode arranged adjacently to the first electrode on the insulating substrate and electrically connected to the heat-generating resistor;

a first meltable conductor arranged between the first and third electrodes to constitute a current path capable of being blown by a heat generated by the heat-generating resistor; and

a first external connecting electrode continuous with the first electrode formed on the same surface as the first and second electrodes, and a second external connecting electrode continuous with the second electrode,

wherein the first electrode is connected to the mounting target via the first external connecting terminal connected to the first external connecting electrode, and the second electrode is connected to the mounting target via the second external connecting terminal connected to the second external connecting electrode, and

wherein a combined resistance of the first external connecting terminal and the second external connecting terminal is lower than a conduction resistance between the first and second external connecting electrodes when the first meltable conductor is melted by the heat from the heat-generating resistor and gather on the first and second electrodes to short-circuit the first and second electrodes.