Protection element

• US 10,090,509 B2
• Filed: 08/30/2013
• Issued: 10/02/2018
• Est. Priority Date: 08/31/2012
• Status: Active Grant

• Current Assignee: Littelfuse Japan G.K. (Littelfuse Incorporated)
• Original Assignee: Littelfuse Japan G.K. (Littelfuse Incorporated)
• Inventors: Tanaka, Arata, Usui, Hisashi, Nomura, Keiichiro
• Primary Examiner(s): Vortman, Anatoly
• Application Number:
  US14/424,398
• Publication Number:
  US 20160099458A1
• Time in Patent Office: 1,859 Days
• Field of Search: 337416
• CPC Class Codes: H01C 7/02 having positive temperature coefficient ceramics C04B
• CPC Class Codes: H01C 7/021 formed as one or more layers or coatings
• CPC Class Codes: H01H 2085/025 Structural association with a binding post of a storage battery
• CPC Class Codes: H01H 85/08 characterised by the shape or form of the fusible member
• CPC Class Codes: H01H 85/11 with applied local area of a metal which, on melting, forms a eutectic with the main material of the fusible member, i.e. M-effect devices
• CPC Class Codes: H01M 10/0525 Rocking-chair batteries, i.e. batteries with lithium insertion or intercalation in both electrodes; Lithium-ion batteries
• CPC Class Codes: H01M 2200/106 PTC
• CPC Class Codes: H01M 50/574 Devices or arrangements for the interruption of current
• CPC Class Codes: H01M 50/581 in response to temperature
• CPC Class Codes: H01M 50/583 in response to current, e.g. fuses
• CPC Class Codes: Y02E 60/10 Energy storage using batteries

Abstract

The present invention provides a protection device which includes: a PTC laminar element which is formed of an insulation resin and has at least one throughhole; electrically conductive metal thin layers which are positioned on each of main surfaces of the laminar element, and a fuse layer which is positioned on a side surface defining at least one of said at least one throughhole and electrically connects the electrically conductive metal thin layers which are positioned on each of main surfaces of the laminar element. The protection device of the present invention allows a larger amount of a current to flow therethrough and can provide a protection from an excessive current.

Claims

1. A protection device comprising:

an annular PTC laminar element formed of a PTC composition and having a central throughhole and at least one surrounding throughhole;

an annular metal foil disposed on each main surface of the PTC laminar element and coaxial with the PTC laminar element;

an annular electrically conductive metal thin layer disposed on each of the metal foils and coaxial with the PTC laminar element; and

a fuse layer which is positioned on a side surface defining at least one of said at least one surrounding throughhole and electrically connecting the electrically conductive metal thin layers;

wherein the fuse layer comprises a first metal layer having a first thickness and a second metal layer having a second thickness greater than the first thickness, and wherein a side surface defining the central throughhole does not include a fuse layer disposed thereon.

2. The protection device according to claim 1, characterized in that the first metal layer consists of a metal having a higher melting point than a melting point of a metal from which the second metal layer is formed.

3. The protection device according to claim 2, characterized in that the metal having the higher melting point is Ni.

4. The protection device according to claim 2, characterized in that the metal having the lower melting point has a melting point lower than a decomposition temperature of a polymer material of the PTC composition.

5. The protection device according to claim 4, characterized in that the metal having the lower melting point is Sn, an Sn—

Cu alloy or an Sn—

Bi alloy.

6. The protection device according to claim 2, characterized in that the first metal layer is formed by electroless plating with the metal having the higher melting point and the second metal layer is formed by electrolytic plating with the metal having the lower melting point on the first metal layer.

7. The protection device according to claim 2, characterized in that a thickness ratio between the first metal layer and the second metal layer is 1:

100-5;

1.

8. The protection device according to claim 1, characterized in that the metal foil is a nickel foil.

9. An electrical apparatus comprising the protection device according to claim 1.

10. A washer comprising:

an annular PTC laminar element formed of a PTC composition and having a central throughhole and at least one surrounding throughhole,

an annular metal foil positioned on each main surface of the PTC laminar element and coaxial with the PTC laminar element;

an annular electrically conductive metal thin layer disposed on each of the metal foils and coaxial with the PTC laminar element, and

a fuse layer positioned on a side surface defining at least one of said at least one surrounding throughhole and electrically connecting the electrically conductive metal thin layers;

wherein the fuse layer comprises a first metal layer having a first thickness and a second metal layer having a second thickness greater than the first thickness, and wherein a side surface defining the central throughhole does not include a fuse layer disposed thereon.

11. The protection device according to claim 10, characterized in that the first metal layer consists of a metal having a higher melting point than a melting point of a metal from which the second metal layer is formed.