Fuse element and protective element
AssigneeSCHOTT Japan Corporation
InventorsShintaro Nakajima, Tsuyoshi Hattori
Life of this patent
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Abstract
A protective element includes an insulating substrate, a plurality of electrodes provided on the insulating substrate, a fuse element electrically connected to any electrode of the plurality of electrodes, and a heat generation element provided on the insulating substrate for heating and fusing the fuse element. The fuse element contains a composite metal material in which a first fusible metal and a second fusible metal are stacked, some of a component of the first fusible metal being dissolved at a joint working temperature, the second fusible metal being lower in melt temperature than the first fusible metal, at least some of a component of the second fusible metal being molten at the joint working temperature.
Claims11
A fuse element comprising:
- a composite metal material including a first fusible metal and a second fusible metal, the second fusible metal having a melt temperature lower than a melt temperature of the first fusible metal;
- wherein
- some of an element of the first fusible metal is molten at a reflow temperature, and at least some of an element of the second fusible metal is molten at the reflow temperature;
- the first fusible metal is an Sn—Ag alloy containing more than 20 mass % and at most 30 mass % of Ag;
- the second fusible metal is an Sn—Bi alloy containing at least 40 mass % and at most 70 mass % of Bi;
- and
- a difference between a liquidus temperature and a solidus temperature of the first fusible metal and the second fusible metal is reduced by equilibrium displacement of Sn between the first fusible metal and the second fusible metal, and mutual diffusion of Ag and Bi between the first fusible metal and the second fusible metal so as to reduce a range of an operating temperature of the fuse element.
A protective element comprising:
- an insulating substrate;
- a plurality of electrodes provided on the insulating substrate;
- a fuse element electrically connected to any of the plurality of electrodes;
- and
- a heat generation element provided on the insulating substrate to heat and fuse the fuse element;
- wherein the fuse element comprising:
- a first fusible metal and a second fusible metal, the second fusible metal having a melt temperature lower than a melt temperature of the first fusible metal;
- wherein
- some of an element of the first fusible metal is molten at a reflow temperature, and at least some of an element of the second fusible metal is molten at the reflow temperature;
- the first fusible metal is an Sn—Ag alloy containing more than 20 mass % and at most 30 mass % of Ag;
- the second fusible metal is an Sn—Bi alloy containing at least 40 mass % and at most 70 mass % of Bi;
- and
- a difference between a liquidus temperature and a solidus temperature of the first fusible metal and the second fusible metal is reduced by equilibrium displacement of Sn between the first fusible metal and the second fusible metal, and mutual diffusion of Ag and Bi between the first fusible metal and the second fusible metal so as to reduce a range of an operating temperature of the fuse element.
Dependencies are inferred from the claim text.