THERMAL SAFETY DEVICE

• US 20130234822A1
• Filed: 07/26/2011
• Published: 09/12/2013
• Est. Priority Date: 07/26/2010
• Status: Active Grant

• Current Assignee: Vishay Bccomponents Beyschlag GMBH (Vishay Intertechnology Incorporated)
• Original Assignee: Vishay Bccomponents Beyschlag GMBH (Vishay Intertechnology Incorporated)
• Inventors: Werner, Wolfgang, Aurich, Joachim, Zum Felde, Ulf, Krueger, Bernd, Mex, Laurent
• Granted Patent: US 9,899,171 B2
• Time in Patent Office: Days
• US Class Current: 337/416
• CPC Class Codes: B22D 41/015 with external heating, i.e. the heat source not being a part of the ladle
• CPC Class Codes: H01H 2037/768 characterised by the composition of the fusible material
• CPC Class Codes: H01H 2085/0412 specially adapted for being mounted on a printed circuit board
• CPC Class Codes: H01H 2085/0414 Surface mounted fuses
• CPC Class Codes: H01H 37/32 Thermally-sensitive members
• CPC Class Codes: H01H 37/761 with a fusible element forming part of the switched circuit H01H37/767 takes precedence
• CPC Class Codes: H01H 85/0411 Miniature fuses
• CPC Class Codes: H01H 85/06 characterised by the fusible material H01H85/11 takes precedence
• CPC Class Codes: H01H 85/08 characterised by the shape or form of the fusible member
• CPC Class Codes: H01H 85/12 Two or more separate fusible members in parallel

Abstract

In order to provide a method for isolating a circuit and a thermal link, wherein the link has a very low resistance and is suitable for high currents, in particular very high short load currents, and also has a high degree of reliability, in particular under difficult conditions, such as thermal and mechanical loading which lasts for a relatively long time, for example, the invention proposes that, during the phase transition of the material of the fusible element (10) from the solid to the liquid state, the volume of the fusible element (10) increases and the pressure increases and, owing to the increase in volume and the increase in pressure, the fusible element (10) is dislodged so as to break the electrical connection.

Claims

1. A thermal safety device (100, 200, 300), which executes the disconnection of an electrical circuit by the melting of a fusible element (10), wherein the thermal safety device has at least two electrically conductive terminals (11, 12) and one fusible element (10), characterised in that, the thermal safety device has an encapsulation or encasement (18), wherein the thermal safety device, i.e. its layered structure, has at least one coating (23) between the terminals (11, 12) and the encapsulation or encasement (18), wherein the thermal safety device is enclosed by an encapsulation or encasement (18), at least in certain regions, wherein the fusible element (10) is encapsulated within the thermal safety device.

2. The thermal safety device in accordance with claim 1, characterised in that, the fusible element (10) is in direct contact with the terminals (11, 12) and the encapsulation or encasement (18).

3. The thermal safety device in accordance with one of the preceding claims, characterised in that, the encapsulation or encasement (18) has a layer of lacquer on the inner face towards the fusible element (10).

4. The thermal safety device in accordance with one of the preceding claims, characterised in that, the thermal safety device has a flux (16).

5. The thermal safety device in accordance with one of the preceding claims, characterised in that, the fusible element (10) is located between the two terminals (11, 12).

6. The thermal safety device in accordance with one of the preceding claims, characterised in that, the coating (23) between the terminals (11, 12) and the encapsulation or encasement (18) contains tin, indium, bismuth, or an alloy of tin, indium, or bismuth.

7. The thermal safety device in accordance with one of the preceding claims, characterised in that, the coating (23) between the terminals (11, 12) and the encapsulation or encasement (18) has a thickness of between 1 μ

m and 50 μ

m, preferably of between 5 μ

m and 20 μ

m.

8. The thermal safety device in accordance with at least one of the claims 5 to 11, characterised in that, the coating (23) between the terminals (11, 12) and the encapsulation or encasement (18) has a nickel undercoat, wherein the nickel undercoat consists of a layer of nickel, or an alloy containing nickel.

9. The thermal safety device in accordance with claim 8, characterised in that, the nickel undercoat has a thickness of between 1 μ

m and 50 μ

m, preferably of between 5 μ

m and 15 μ

m.

10. The thermal safety device in accordance with one of the preceding claims, characterised in that, the fusible element (10) consists of a low melting point metal, an alloy containing a low melting point metal, or a lead solder.

11. The thermal safety device in accordance with one of the preceding claims, characterised in that, the fusible element (10) consists of a tin-silver alloy.

12. The thermal safety device in accordance with one of the preceding claims, characterised in that, the terminals (11, 12) have the form of caps.

13. The thermal safety device in accordance with at least one of the claims 1 to 11, characterised in that, the terminals (11, 12) have the form of a cuboid, or a form similar to that of a cuboid.

14. The thermal safety device in accordance with one of the preceding claims, characterised in that, the thermal safety device has at least one electrically non-conductive body (13), wherein the said at least one electrically non-conductive body (13) serves to hold the terminals (11, 12).

15. The thermal safety device in accordance with claim 14, characterised in that, the at least one electrically non-conductive body (13) consists of ceramic, glass, plastic, or another organic material.

16. The thermal safety device in accordance with one of the preceding claims, characterised in that, the fusible element (10) has the form of a ring.

17. The thermal safety device in accordance with one of the preceding claims, characterised in that, an electrical conductor (14, 15) is connected to each of the terminals (11, 12).

18. The thermal safety device in accordance with at least claim 17, characterised in that, the electrical conductor (14, 15) has the form of a wire, or a form that is similar to that of a wire.

19. The thermal safety device in accordance with one of the preceding claims, characterised in that, the thermal safety device has a lacquer covering, or a lacquer encasement.

20. An application of a thermal safety device in accordance with at least one of the preceding claims as a fusible safety device, for purposes of protecting solar cells, high energy battery cells, ancillary heating systems, electrical loads, in particular in vehicles, and also for purposes of protection from excess temperature, and fire protection.