PROTECTION ELEMENT

• US 20150084734A1
• Filed: 03/27/2013
• Published: 03/26/2015
• Est. Priority Date: 03/29/2012
• Status: Active Grant

• Current Assignee: Dexerials Corporation
• Original Assignee: Dexerials Corporation
• Inventors: Yoneda, Yoshihiro
• Granted Patent: US 10,008,356 B2
• Time in Patent Office: Days
• US Class Current: 337/183
• CPC Class Codes: H01H 2037/046 being soldered on the printed circuit to be protected
• CPC Class Codes: H01H 37/761 with a fusible element forming part of the switched circuit H01H37/767 takes precedence
• CPC Class Codes: H01H 85/06 characterised by the fusible material H01H85/11 takes precedence
• CPC Class Codes: Y02E 60/10 Energy storage using batteries

Abstract

The present invention aims to achieve a Pb-free protection element by using a layered body including a high melting point metal layer and a low melting point metal layer. A protection element includes an insulating substrate, a heating body, an insulating member, two electrodes, a heating body extraction electrode, and a fusible conductor. Furthermore, the fusible conductor includes a layered body including at least a high melting point metal layer and a low melting point metal layer, and the low melting point metal layer is melted by a heat generated by the heating body, whereby, while eroding the high melting point metal layer, the low melting point metal layer is drawn close to the side of the two electrodes and the heating body extraction electrode, and fused, the two electrodes and the heating body extraction electrode each having high wettability for the low melting point metal layer.

Claims

1. A protection element, comprising:

an insulating substrate;

a heating body laminated on the insulating substrate;

an insulating member laminated on the insulating substrate so as to cover at least the heating body;

first and second electrodes laminated on the insulating substrate having the insulating member laminated thereon;

a heating body extraction electrode laminated on the insulating member so as to be superimposed with the heating body, and electrically connected to said heating body on a current path between the first and second electrodes; and

a fusible conductor laminated over a range from the heating body extraction electrode to the first and second electrodes, and fusing the current path between the first and second electrodes by heating,

wherein the fusible conductor comprises a layered body including at least a high melting point metal layer and a low melting point metal layer, and

wherein the low melting point metal layer is melted by a heat generated by the heating body, whereby, while eroding the high melting point metal layer, the low melting point metal layer is drawn close to a side of the first and second electrodes and the heating body extraction electrode, and fused, said first and second electrodes and said heating body extraction electrode each having high wettability for the low melting point metal.

2. The protection element according to claim 1, wherein the low melting point metal layer is made of Pb-free solder, meanwhile the high melting point metal layer is made of Ag or Cu, or a metal containing Ag or Cu as a main component.

3. The protection element according to claim 1, wherein the fusible conductor is connected by a low melting point metal at positions to be connected to the first and second electrodes and the heating body extraction electrode.

4. The protection element according to claim 1, wherein the fusible conductor has a coating structure including a high melting point metal layer as an internal layer and a low melting point metal layer as an external layer.

5. The protection element according to claim 4, wherein the low melting point metal layer is formed so as to penetrate at least a part of the high melting point metal layer.

6. The protection element according to claim 1, wherein the fusible conductor has a coating structure including a low melting point metal layer as an internal layer and a high melting point metal layer as an external layer.

7. The protection element according to claim 1, wherein the fusible conductor has a two-layer structure including a high melting point metal layer as an upper layer and a low melting point metal layer as a lower layer.

8. The protection element according to claim 1, wherein any one plating treatment selected from Ni/Au plating, Ni/Pd plating, and Ni/Pd/Au plating is performed on surfaces of the first and second electrodes and the heating body extraction electrode.

9. The protection element according to claim 1, wherein an insulating member layer is provided between the heating body and the insulating substrate.

10. The protection element according to claim 1, wherein the low melting point metal layer has a larger volume than the high melting point metal layer has.

11. The protection element according to claim 1, wherein the fusible conductor has a coating structure including a low melting point metal layer as an internal layer and a high melting point metal layer as an external layer, and an entire surface of the low melting point metal layer serving as an internal layer is coated with the high melting point metal layer.

12. The protection element according to claim 1, wherein the fusible conductor has a coating structure including a low melting point metal layer as an internal layer and a high melting point metal layer as an external layer, and is connected on the first and second electrodes via an electrically conductive paste.

13. The protection element according to claim 1, wherein the fusible conductor has a coating structure including a low melting point metal layer as an internal layer and a high melting point metal layer as an external layer, and is connected on the first and second electrodes by welding.

14. The protection element according to claim 1, wherein the fusible conductor has a coating structure including a low melting point metal layer as an internal layer and a high melting point metal layer as an external layer;

a surface of said low melting point metal layer serving as an internal layer is coated with the high melting point metal layer; and

a surface of said high melting point metal layer is coated with a second low melting point metal layer.

15. The protection element according to claim 1, wherein the fusible conductor has a coating structure including a low melting point metal layer as an internal layer and a high melting point metal layer as an external layer, and a layer thickness ratio of the low melting point metal layer to the high melting point metal layer is from 2.1:

1 to 100;

1.

38. The protection element according to claim 2, wherein the fusible conductor has a coating structure including a high melting point metal layer as an internal layer and a low melting point metal layer as an external layer.

39. The protection element according to claim 3, wherein the fusible conductor has a coating structure including a high melting point metal layer as an internal layer and a low melting point metal layer as an external layer.

40. The protection element according to claim 38, wherein the low melting point metal layer is formed so as to penetrate at least a part of the high melting point metal layer.

41. The protection element according to claim 39, wherein the low melting point metal layer is formed so as to penetrate at least a part of the high melting point metal layer.

42. The protection element according to claim 2, wherein the fusible conductor has a coating structure including a low melting point metal layer as an internal layer and a high melting point metal layer as an external layer.

43. The protection element according to claim 3, wherein the fusible conductor has a coating structure including a low melting point metal layer as an internal layer and a high melting point metal layer as an external layer.

44. The protection element according to claim 2 wherein the fusible conductor has a two-layer structure including a high melting point metal layer as an upper layer and a low melting point metal layer as a lower layer.

45. The protection element according to claim 3 wherein the fusible conductor has a two-layer structure including a high melting point metal layer as an upper layer and a low melting point metal layer as a lower layer.

46. The protection element according to claim 2, wherein any one plating treatment selected from Ni/Au plating, Ni/Pd plating, and Ni/Pd/Au plating is performed on surfaces of the first and second electrodes and the heating body extraction electrode.

47. The protection element according to claim 3, wherein any one plating treatment selected from Ni/Au plating, Ni/Pd plating, and Ni/Pd/Au plating is performed on surfaces of the first and second electrodes and the heating body extraction electrode.

48. The protection element according to claim 2, wherein an insulating member layer is provided between the heating body and the insulating substrate.

49. The protection element according to claim 3, wherein an insulating member layer is provided between the heating body and the insulating substrate.

50. The protection element according to claim 2 wherein the low melting point metal layer has a larger volume than the high melting point metal layer has.

51. The protection element according to claim 3 wherein the low melting point metal layer has a larger volume than the high melting point metal layer has.

52. The protection element according to claim 11, wherein the fusible conductor has a coating structure including a low melting point metal layer as an internal layer and a high melting point metal layer as an external layer, and is connected on the first and second electrodes via an electrically conductive paste.

53. The protection element according to claim 11, wherein the fusible conductor has a coating structure including a low melting point metal layer as an internal layer and a high melting point metal layer as an external layer, and is connected on the first and second electrodes by welding.

54. The protection element according to claim 11, wherein the fusible conductor has a coating structure including a low melting point metal layer as an internal layer and a high melting point metal layer as an external layer;

a surface of said low melting point metal layer serving as an internal layer is coated with the high melting point metal layer; and

a surface of said high melting point metal layer is coated with a second low melting point metal layer.

55. The protection element according to claim 11, wherein the fusible conductor has a coating structure including a low melting point metal layer as an internal layer and a high melting point metal layer as an external layer, and a layer thickness ratio of the low melting point metal layer to the high melting point metal layer is from 2.1:

1 to 100;

1.

16. A protection element, comprising:

an insulating substrate;

a heating body laminated on the insulating substrate;

an insulating member laminated on the insulating substrate so as to cover at least the heating body;

first and second electrodes laminated on the insulating substrate having the insulating member laminated thereon;

a heating body extraction electrode electrically connected to said heating body on a current path between the first and second electrodes; and

a fusible conductor laminated over a range from the heating body extraction electrode to the first and second electrodes and fusing the current path between the first and second electrodes by heating,

wherein the fusible conductor comprises a layered body including at least a high melting point metal layer and a low melting point metal layer, and

wherein the low melting point metal layer is melted by a heat generated by the heating body, whereby, while eroding the high melting point metal layer, the low melting point metal layer is drawn close to a side of the first and second electrodes and the heating body extraction electrode, and fused, said first and second electrodes and said heating body extraction electrode each having high wettability for the low melting point metal.

24. The protection element according to claim 16, wherein the low melting point metal layer is made of Pb-free solder, meanwhile the high melting point metal layer is made of Ag or Cu, or a metal containing Ag or Cu as a main component.

25. The protection element according to claim 16, wherein a film containing Au or Au as a main component is formed on a surface of the high melting point metal layer.

26. The protection element according to claim 16, wherein the fusible conductor is connected by a low melting point metal at positions to be connected to the first and second electrodes and the heating body extraction electrode.

27. The protection element according to claim 16, wherein the fusible conductor has a coating structure including a high melting point metal layer as an internal layer and a low melting point metal layer as an external layer.

28. The protection element according to claim 27, wherein the low melting point metal layer is formed so as to penetrate at least a part of the high melting point metal layer.

29. The protection element according to claim 16, wherein the fusible conductor has a coating structure including a low melting point metal layer as an internal layer and a high melting point metal layer as an external layer.

30. The protection element according to claim 16, wherein the high melting point metal layer has an opening on a surface thereof, whereby the low melting point metal layer is exposed therefrom.

31. The protection element according to claim 16, wherein the fusible conductor has a two-layer structure including a high melting point metal layer as an upper layer and a low melting point metal layer as a lower layer.

32. The protection element according to claim 16, wherein the fusible conductor has a two-layer structure including a low melting point metal layer as an upper layer and a high melting point metal layer as a lower layer.

33. The protection element according to claim 16, wherein the high melting point metal layer and the low melting point metal layer are alternately laminated to form the fusible conductor having four or more layers.

34. The protection element according to claim 16, wherein any one plating treatment selected from Ni/Au plating, Ni/Pd plating, and Ni/Pd/Au plating is performed on surfaces of the first and second electrodes and the heating body extraction electrode.

35. The protection element according to claim 16, wherein an insulating member layer is provided between the heating body and the insulating substrate.

36. The protection element according to claim 16, wherein the low melting point metal layer has a larger volume than the high melting point metal layer has.

17. A protection element, comprising:

an insulating substrate;

a heating body laminated on the insulating substrate;

an insulating member laminated on the insulating substrate so as to cover at least the heating body;

first and second electrodes laminated on the insulating substrate having the insulating member laminated thereon;

a heating body extraction electrode electrically connected to said heating body on a current path between the first and second electrodes; and

a plurality of fusible conductors laminated over a range from the heating body extraction electrode to the first and second electrodes, and fusing the current path between said first and second electrodes by heating,

wherein each of the fusible conductors comprises a layered body including at least a high melting point metal layer and a low melting point metal layer, and

wherein the low melting point metal layer is melted by a heat generated by the heating body, whereby, while eroding the high melting point metal layer, the low melting point metal layer is drawn close to a side of the first and second electrodes and the heating body extraction electrode, and fused, said first and second electrodes and said heating body extraction electrode each having high wettability for the low melting point metal.

18. The protection element according to claim 17, wherein, in the heating body extraction electrode on which the plurality of the fusible conductors is laminated, an insulating layer is formed between the plurality of fusible conductors.

19. The protection element according to claim 17, wherein, in the heating body extraction electrode, a portion between the plurality of fusible conductors is formed to be narrower than a portion on which the plurality of fusible conductors is laminated.

56. The protection element according claim 17, wherein the low melting point metal layer is made of Pb-free solder, meanwhile the high melting point metal layer is made of Ag or Cu, or a metal containing Ag or Cu as a main component.

57. The protection element according claim 18, wherein the low melting point metal layer is made of Pb-free solder, meanwhile the high melting point metal layer is made of Ag or Cu, or a metal containing Ag or Cu as a main component.

58. The protection element according claim 19, wherein the low melting point metal layer is made of Pb-free solder, meanwhile the high melting point metal layer is made of Ag or Cu, or a metal containing Ag or Cu as a main component.

63. The protection element according to claim 17, wherein a film containing Au or Au as a main component is formed on a surface of the high melting point metal layer.

64. The protection element according to claim 18, wherein a film containing Au or Au as a main component is formed on a surface of the high melting point metal layer.

65. The protection element according to claim 19, wherein a film containing Au or Au as a main component is formed on a surface of the high melting point metal layer.

70. The protection element according to 17, wherein the fusible conductor is connected by a low melting point metal at positions to be connected to the first and second electrodes and the heating body extraction electrode.

71. The protection element according to 18, wherein the fusible conductor is connected by a low melting point metal at positions to be connected to the first and second electrodes and the heating body extraction electrode.

72. The protection element according to 19, wherein the fusible conductor is connected by a low melting point metal at positions to be connected to the first and second electrodes and the heating body extraction electrode.

77. The protection element according to claim 17, wherein the fusible conductor has a coating structure including a high melting point metal layer as an internal layer and a low melting point metal layer as an external layer.

78. The protection element according to claim 18, wherein the fusible conductor has a coating structure including a high melting point metal layer as an internal layer and a low melting point metal layer as an external layer.

79. The protection element according to claim 19, wherein the fusible conductor has a coating structure including a high melting point metal layer as an internal layer and a low melting point metal layer as an external layer.

84. The protection element according to claim 77, wherein the low melting point metal layer is formed so as to penetrate at least a part of the high melting point metal layer.

85. The protection element according to claim 78, wherein the low melting point metal layer is formed so as to penetrate at least a part of the high melting point metal layer.

86. The protection element according to claim 79, wherein the low melting point metal layer is formed so as to penetrate at least a part of the high melting point metal layer.

91. The protection element according to claim 17, wherein the fusible conductor has a coating structure including a low melting point metal layer as an internal layer and a high melting point metal layer as an external layer.

92. The protection element according to claim 18, wherein the fusible conductor has a coating structure including a low melting point metal layer as an internal layer and a high melting point metal layer as an external layer.

93. The protection element according to claim 19, wherein the fusible conductor has a coating structure including a low melting point metal layer as an internal layer and a high melting point metal layer as an external layer.

98. The protection element according to claim 17, wherein the high melting point metal layer has an opening on a surface thereof, whereby the low melting point metal layer is exposed therefrom.

99. The protection element according to claim 18, wherein the high melting point metal layer has an opening on a surface thereof, whereby the low melting point metal layer is exposed therefrom.

100. The protection element according to claim 19, wherein the high melting point metal layer has an opening on a surface thereof, whereby the low melting point metal layer is exposed therefrom.

105. The protection element according to claim 17, wherein the fusible conductor has a two-layer structure including a high melting point metal layer as an upper layer and a low melting point metal layer as a lower layer.

106. The protection element according to claim 18, wherein the fusible conductor has a two-layer structure including a high melting point metal layer as an upper layer and a low melting point metal layer as a lower layer.

107. The protection element according to claim 19, wherein the fusible conductor has a two-layer structure including a high melting point metal layer as an upper layer and a low melting point metal layer as a lower layer.

112. The protection element according to claim 17, wherein the fusible conductor has a two-layer structure including a low melting point metal layer as an upper layer and a high melting point metal layer as a lower layer.

113. The protection element according to claim 18, wherein the fusible conductor has a two-layer structure including a low melting point metal layer as an upper layer and a high melting point metal layer as a lower layer.

114. The protection element according to claim 19, wherein the fusible conductor has a two-layer structure including a low melting point metal layer as an upper layer and a high melting point metal layer as a lower layer.

119. The protection element according to claim 17, wherein the high melting point metal layer and the low melting point metal layer are alternately laminated to form the fusible conductor having four or more layers.

120. The protection element according to claim 18, wherein the high melting point metal layer and the low melting point metal layer are alternately laminated to form the fusible conductor having four or more layers.

121. The protection element according to claim 19, wherein the high melting point metal layer and the low melting point metal layer are alternately laminated to form the fusible conductor having four or more layers.

126. The protection element according to claim 17, wherein any one plating treatment selected from Ni/Au plating, Ni/Pd plating, and Ni/Pd/Au plating is performed on surfaces of the first and second electrodes and the heating body extraction electrode.

127. The protection element according to claim 18, wherein any one plating treatment selected from Ni/Au plating, Ni/Pd plating, and Ni/Pd/Au plating is performed on surfaces of the first and second electrodes and the heating body extraction electrode.

128. The protection element according to claim 19, wherein any one plating treatment selected from Ni/Au plating, Ni/Pd plating, and Ni/Pd/Au plating is performed on surfaces of the first and second electrodes and the heating body extraction electrode.

133. The protection element according to claim 17, wherein an insulating member layer is provided between the heating body and the insulating substrate.

134. The protection element according to claim 18, wherein an insulating member layer is provided between the heating body and the insulating substrate.

135. The protection element according to claim 19, wherein an insulating member layer is provided between the heating body and the insulating substrate.

140. The protection element according to claim 17, wherein the low melting point metal layer has a larger volume than the high melting point metal layer has.

141. The protection element according to claim 18, wherein the low melting point metal layer has a larger volume than the high melting point metal layer has.

142. The protection element according to claim 19, wherein the low melting point metal layer has a larger volume than the high melting point metal layer has.

20. A protection element, comprising:

an insulating substrate;

a heating body built inside the insulating substrate;

first and second electrodes laminated on the insulating substrate;

a heating body extraction electrode electrically connected to said heating body on a current path between the first and second electrodes; and

a fusible conductor laminated over a range from the heating body extraction electrode to the first and second electrodes, and fusing the current path between said first and second electrodes by heating of the heating body,

wherein the fusible conductor comprises a layered body including at least a high melting point metal layer and a low melting point metal layer, and

wherein the low melting point metal layer is melted by a heat generated by the heating body, whereby, while eroding the high melting point metal layer, the low melting point metal layer is drawn close to a side of the first and second electrodes and the heating body extraction electrode, and fused, said first and second electrodes and said heating body extraction electrode each having high wettability for the low melting point metal.

59. The protection element according claim 20, wherein the low melting point metal layer is made of Pb-free solder, meanwhile the high melting point metal layer is made of Ag or Cu, or a metal containing Ag or Cu as a main component.

66. The protection element according to claim 20, wherein a film containing Au or Au as a main component is formed on a surface of the high melting point metal layer.

73. The protection element according to 20, wherein the fusible conductor is connected by a low melting point metal at positions to be connected to the first and second electrodes and the heating body extraction electrode.

80. The protection element according to claim 20, wherein the fusible conductor has a coating structure including a high melting point metal layer as an internal layer and a low melting point metal layer as an external layer.

87. The protection element according to claim 80, wherein the low melting point metal layer is formed so as to penetrate at least a part of the high melting point metal layer.

94. The protection element according to claim 20, wherein the fusible conductor has a coating structure including a low melting point metal layer as an internal layer and a high melting point metal layer as an external layer.

101. The protection element according to claim 20, wherein the high melting point metal layer has an opening on a surface thereof, whereby the low melting point metal layer is exposed therefrom.

108. The protection element according to claim 20, wherein the fusible conductor has a two-layer structure including a high melting point metal layer as an upper layer and a low melting point metal layer as a lower layer.

115. The protection element according to claim 20, wherein the fusible conductor has a two-layer structure including a low melting point metal layer as an upper layer and a high melting point metal layer as a lower layer.

122. The protection element according to claim 20, wherein the high melting point metal layer and the low melting point metal layer are alternately laminated to form the fusible conductor having four or more layers.

129. The protection element according to claim 20, wherein any one plating treatment selected from Ni/Au plating, Ni/Pd plating, and Ni/Pd/Au plating is performed on surfaces of the first and second electrodes and the heating body extraction electrode.

136. The protection element according to claim 20, wherein an insulating member layer is provided between the heating body and the insulating substrate.

143. The protection element according to claim 20, wherein the low melting point metal layer has a larger volume than the high melting point metal layer has.

21. A protection element, comprising:

an insulating substrate;

a heating body laminated on the insulating substrate;

first and second electrodes laminated on a surface of the insulating substrate opposite to a surface thereof on which the heating body is laminated;

a heating body extraction electrode electrically connected to said heating body on a current path between the first and second electrodes; and

a fusible conductor laminated over a range from the heating body extraction electrode to the first and second electrodes, and fusing the current path between said first and second electrodes by heating of the heating body,

wherein the fusible conductor comprises a layered body including at least a high melting point metal layer and a low melting point metal layer, and

wherein the low melting point metal layer is melted by a heat generated by the heating body, whereby, while eroding the high melting point metal layer, the low melting point metal layer is drawn close to a side of the first and second electrodes and the heating body extraction electrode, and fused, said first and second electrodes and said heating body extraction electrode each having high wettability for the low melting point metal.

60. The protection element according claim 21, wherein the low melting point metal layer is made of Pb-free solder, meanwhile the high melting point metal layer is made of Ag or Cu, or a metal containing Ag or Cu as a main component.

67. The protection element according to claim 21, wherein a film containing Au or Au as a main component is formed on a surface of the high melting point metal layer.

74. The protection element according to 21, wherein the fusible conductor is connected by a low melting point metal at positions to be connected to the first and second electrodes and the heating body extraction electrode.

81. The protection element according to claim 21, wherein the fusible conductor has a coating structure including a high melting point metal layer as an internal layer and a low melting point metal layer as an external layer.

88. The protection element according to claim 81, wherein the low melting point metal layer is formed so as to penetrate at least a part of the high melting point metal layer.

95. The protection element according to claim 21, wherein the fusible conductor has a coating structure including a low melting point metal layer as an internal layer and a high melting point metal layer as an external layer.

102. The protection element according to claim 21, wherein the high melting point metal layer has an opening on a surface thereof, whereby the low melting point metal layer is exposed therefrom.

109. The protection element according to claim 21, wherein the fusible conductor has a two-layer structure including a high melting point metal layer as an upper layer and a low melting point metal layer as a lower layer.

116. The protection element according to claim 21, wherein the fusible conductor has a two-layer structure including a low melting point metal layer as an upper layer and a high melting point metal layer as a lower layer.

123. The protection element according to claim 21, wherein the high melting point metal layer and the low melting point metal layer are alternately laminated to form the fusible conductor having four or more layers.

130. The protection element according to claim 21, wherein any one plating treatment selected from Ni/Au plating, Ni/Pd plating, and Ni/Pd/Au plating is performed on surfaces of the first and second electrodes and the heating body extraction electrode.

137. The protection element according to claim 21, wherein an insulating member layer is provided between the heating body and the insulating substrate.

144. The protection element according to claim 21, wherein the low melting point metal layer has a larger volume than the high melting point metal layer has.

22. A protection element, comprising:

an insulating substrate;

a heating body laminated on the insulating substrate;

first and second electrodes laminated on a same surface of the insulating substrate as a surface thereof on which the heating body is laminated;

a heating body extraction electrode electrically connected to said heating body on a current path between the first and second electrodes; and

a fusible conductor laminated over a range from the heating body extraction electrode to the first and second electrodes, and fusing the current path between the first and second electrodes by heating of the heating body,

wherein the fusible conductor comprises a layered body including at least a high melting point metal layer and a low melting point metal layer, and

wherein the low melting point metal layer is melted by a heat generated by the heating body, whereby, while eroding the high melting point metal layer, the low melting point metal layer is drawn close to a side of the first and second electrodes and the heating body extraction electrode, and fused, said first and second electrodes and said heating body extraction electrode each having high wettability for the low melting point metal.

61. The protection element according claim 22, wherein the low melting point metal layer is made of Pb-free solder, meanwhile the high melting point metal layer is made of Ag or Cu, or a metal containing Ag or Cu as a main component.

68. The protection element according to claim 22, wherein a film containing Au or Au as a main component is formed on a surface of the high melting point metal layer.

75. The protection element according to 22, wherein the fusible conductor is connected by a low melting point metal at positions to be connected to the first and second electrodes and the heating body extraction electrode.

82. The protection element according to claim 22, wherein the fusible conductor has a coating structure including a high melting point metal layer as an internal layer and a low melting point metal layer as an external layer.

89. The protection element according to claim 82, wherein the low melting point metal layer is formed so as to penetrate at least a part of the high melting point metal layer.

96. The protection element according to claim 22, wherein the fusible conductor has a coating structure including a low melting point metal layer as an internal layer and a high melting point metal layer as an external layer.

103. The protection element according to claim 22, wherein the high melting point metal layer has an opening on a surface thereof, whereby the low melting point metal layer is exposed therefrom.

110. The protection element according to claim 22, wherein the fusible conductor has a two-layer structure including a high melting point metal layer as an upper layer and a low melting point metal layer as a lower layer.

117. The protection element according to claim 22, wherein the fusible conductor has a two-layer structure including a low melting point metal layer as an upper layer and a high melting point metal layer as a lower layer.

124. The protection element according to claim 22, wherein the high melting point metal layer and the low melting point metal layer are alternately laminated to form the fusible conductor having four or more layers.

131. The protection element according to claim 22, wherein any one plating treatment selected from Ni/Au plating, Ni/Pd plating, and Ni/Pd/Au plating is performed on surfaces of the first and second electrodes and the heating body extraction electrode.

138. The protection element according to claim 22, wherein an insulating member layer is provided between the heating body and the insulating substrate.

145. The protection element according to claim 22, wherein the low melting point metal layer has a larger volume than the high melting point metal layer has.

23. A protection element, comprising:

an insulating substrate;

first and second electrodes laminated on the insulating substrate;

a heating body extraction electrode laminated on a current path between the first and second electrodes;

a heating element incorporated so as to be electrically connected to the heating body extraction electrode; and

a fusible conductor laminated over a range from the heating body extraction electrode to the first and second electrodes, and fusing the current path between said first and second electrodes by heating of the heating element,

wherein the fusible conductor comprises a layered body including at least a high melting point metal layer and a low melting point metal layer, and

wherein the low melting point metal layer is melted by a heat generated by the heating body, whereby, while eroding the high melting point metal layer, the low melting point metal layer is drawn close to a side of the first and second electrodes and the heating body extraction electrode, and fused, said first and second electrodes and said heating body extraction electrode each having high wettability for the low melting point metal.

62. The protection element according claim 23, wherein the low melting point metal layer is made of Pb-free solder, meanwhile the high melting point metal layer is made of Ag or Cu, or a metal containing Ag or Cu as a main component.

69. The protection element according to claim 23, wherein a film containing Au or Au as a main component is formed on a surface of the high melting point metal layer.

76. The protection element according to 23, wherein the fusible conductor is connected by a low melting point metal at positions to be connected to the first and second electrodes and the heating body extraction electrode.

83. The protection element according to claim 23, wherein the fusible conductor has a coating structure including a high melting point metal layer as an internal layer and a low melting point metal layer as an external layer.

90. The protection element according to claim 83, wherein the low melting point metal layer is formed so as to penetrate at least a part of the high melting point metal layer.

97. The protection element according to claim 23, wherein the fusible conductor has a coating structure including a low melting point metal layer as an internal layer and a high melting point metal layer as an external layer.

104. The protection element according to claim 23, wherein the high melting point metal layer has an opening on a surface thereof, whereby the low melting point metal layer is exposed therefrom.

111. The protection element according to claim 23, wherein the fusible conductor has a two-layer structure including a high melting point metal layer as an upper layer and a low melting point metal layer as a lower layer.

118. The protection element according to claim 23, wherein the fusible conductor has a two-layer structure including a low melting point metal layer as an upper layer and a high melting point metal layer as a lower layer.

125. The protection element according to claim 23, wherein the high melting point metal layer and the low melting point metal layer are alternately laminated to form the fusible conductor having four or more layers.

132. The protection element according to claim 23, wherein any one plating treatment selected from Ni/Au plating, Ni/Pd plating, and Ni/Pd/Au plating is performed on surfaces of the first and second electrodes and the heating body extraction electrode.

139. The protection element according to claim 23, wherein an insulating member layer is provided between the heating body and the insulating substrate.

146. The protection element according to claim 23, wherein the low melting point metal layer has a larger volume than the high melting point metal layer has.

37. A protection element, comprising:

an insulating substrate;

a heating body laminated on the insulating substrate;

an insulating member laminated on the insulating substrate so as to cover at least the heating body;

first and second electrodes laminated on the insulating substrate having the insulating member laminated thereon;

a heating body extraction electrode electrically connected to said heating body on a current path between the first and second electrodes; and

a fusible conductor laminated over a range from the heating body extraction electrode to the first and second electrodes, and fusing the current path between the first and second electrodes by heating,

wherein the fusible conductor is made of a high melting point metal and connected with each of the first electrode, the second electrode, and the heating body extraction electrode via a low melting point metal, and

wherein the low melting point metal layer is melted by a heat generated by the heating body, whereby, while eroding the fusible conductor made of the high melting point metal, the low melting point metal layer is drawn close to a side of the first and second electrodes and the heating body extraction electrode, and fused, said first and second electrodes and said heating body extraction electrode each having high wettability for the low melting point metal.