Surface-mount fuse and the manufacture thereof

• US 5,977,860 A
• Filed: 02/21/1997
• Issued: 11/02/1999
• Est. Priority Date: 06/07/1996
• Status: Expired due to Fees

• Current Assignee: Littelfuse Incorporated
• Original Assignee: Littelfuse Incorporated
• Inventors: Rybka, Matthew Michael, Ulm, Steven Francis Jr., Harris, Edwin James IV
• Primary Examiner(s): Picard, Leo P.
• Assistant Examiner(s): Gandhi, Jayprakash N.
• Application Number:
  US08/804,421
• Time in Patent Office: 984 Days
• Field of Search: 337/152, 337/227, 337/228, 337/297, 337/404, 337/405, 29/623
• US Class Current: 337/297
• CPC Class Codes: H01H 69/022 of printed circuit fuses
• CPC Class Codes: H01H 85/0411 Miniature fuses
• CPC Class Codes: H01H 85/046 Fuses formed as printed circuits
• CPC Class Codes: H01H 85/143 Electrical contacts; Fastening fusible members to such contacts
• CPC Class Codes: H05K 3/3421 Leaded components
• CPC Class Codes: H05K 3/3426 characterised by the leads
• CPC Class Codes: Y02P 70/50 Manufacturing or production processes characterised by the final manufactured product

Abstract

A surface-mount fuse for protecting a circuit, which includes a substrate having first and second surfaces, each surface having first, second, third, and fourth ends, the substrate also having first, second, third, and fourth sides. The fuse includes a metal strip attached to the first surface of the substrate with a layer of adhesive material, the layer of adhesive material being disposed between the metal strip and the first surface of the substrate, the metal strip having a first connection region, a second connection region, and a non-linear fuse link therebetween. The fuse further includes first and second wire leads, the first wire lead being conductively connected to the first connection region and horizontally projecting away from the first connection region, the second wire lead being conductively connected to the second connection region and horizontally projecting away from the second connection region, for connecting the fuse to the remainder of the circuit. Alternatively, the wire leads can include clip leads or other terminal leads. The fuse also includes a protective layer disposed on the fuse link. A method for making the fuse is also disclosed.

Claims

1. A substrate having first and second surfaces, each surface having first, second, third, and fourth ends, the substrate also having first, second, third, and fourth sides;

a metal strip evenly attached to the first surface of the substrate with a laminating adhesive, the laminating adhesive being disposed between the metal strip and the first surface of the substrate, the metal strip having a first connection region, a second connection region, and a fuse link therebetween having an upper surface and a side surface, the first connection region being disposed along substantially the full length of the first end of the first surface of the substrate, the second connection region being disposed along substantially the full length of the second end of the first surface of the substrate; and

first and second leads aligned substantially with and along the first and second connection regions, respectively, the first lead being conductively connected to the first connection region and horizontally projecting away from the first connection region, the second lead being conductively connected to the second connection region and horizontally projecting away from the second connection region, for connecting the fuse to the remainder of the circuit.

2. The surface-mount fuse of claim 1, wherein a protective layer is disposed on the fuse link, the protective layer being in contact with and surrounding the upper and side surfaces of the fuse link of the metal strip.

3. The surface-mount fuse of claim 2, wherein the protective layer is also in contact with at least a fraction of the first and second connection regions of the metal strip.

4. The surface-mount fuse of claim 2, wherein said protective layer is made of a polymeric material.

5. The surface-mount fuse of claim 2, wherein the protective layer is made of an RTV silicone material.

6. The surface-mount fuse of claim 2, wherein a solder material is disposed between the first and second leads and the first and second connection regions, respectively, of the metal strip for connecting the first and second leads to the first and second connection regions.

7. The surface-mount fuse of claim 1, wherein the substrate is made of an FR-4 material.

8. The surface-mount fuse of claim 1, wherein the substrate is made of a melamine-based composition.

9. The surface-mount fuse of claim 8, wherein the melamine-based composition is a type G-5 melamine laminate.

10. The surface-mount fuse of claim 1, wherein the metal strip is made from a zinc alloy.

11. The surface-mount fuse of claim 1, wherein the metal strip is made from a sheet of zinc foil.

12. The surface-mount fuse of claim 1, wherein the laminating adhesive is a blended silicone laminating adhesive.

13. The surface-mount fuse of claim 12, wherein the laminating adhesive has a high viscosity at room temperature.

14. The surface-mount fuse of claim 1, wherein the first and second leads are made of wire.

15. A surface-mount fuse for protecting a circuit including the fuse comprising:

a substrate having a first surface;

a metal strip evenly attached to the first surface of the substrate with a silicone laminating adhesive, the silicone laminating adhesive being disposed between the metal strip and the first surface of the substrate and connecting the substrate to the metal strip, wherein the metal strip has a first connection region, a second connection region, and a fuse link therebetween having an upper surface and a side surface, the first connection region being disposed along substantially the full length of the first end of the first surface of the substrate, the second connection region being disposed along substantially the full length of the second end of the first surface of the substrate;

a first terminal lead being conductively connected to the first connection region and projecting away from the first connection region; and

a second terminal lead being conductively connected to the second connection region and projecting away from the second connection region, the first and second terminal leads connecting the fuse to the remainder of the circuit.

16. The surface-mount fuse of claim 15, wherein a protective layer is disposed on the fuse link, the protective layer in contact with and surrounding the upper and side surfaces of the fuse link of the metal strip.

17. The surface-mount fuse of claim 16, wherein the protective layer is also in contact with at least a fraction of the first and second connection regions of the metal strip.

18. The surface-mount fuse of claim 16, wherein said protective layer is made of a polymeric material.

19. The surface-mount fuse of claim 16, wherein the protective layer is made of an RTV silicone material.

20. The surface-mount fuse of claim 16, wherein a solder material is disposed between the first and second terminal leads and the first and second connection regions, respectively, of the metal strip for connecting the first and second terminal leads to the first and second connection regions.

21. The surface-mount fuse of claim 15, wherein the substrate is made of an FR-4 material.

22. The surface-mount fuse of claim 15, wherein the substrate is made of a melamine-based composition.

23. The surface-mount fuse of claim 22, wherein the melamine-based composition is a type G-5 melamine laminate.

24. The surface-mount fuse of claim 15, wherein the metal strip is made from a zinc alloy.

25. The surface-mount fuse of claim 15, wherein the metal strip is made from a sheet of zinc foil.

26. The surface-mount fuse of claim 15, wherein the layer of polymeric material is a polyimide.

27. The surface-mount fuse of claim 15, wherein the silicone laminating adhesive is a two-component blended material.

28. A surface-mount fuse for protecting a circuit including the fuse comprising:

a substrate having first and second surfaces, each surface having first, second, third, and fourth ends, the substrate also having first, second, third, and fourth sides;

a laminating adhesive disposed on the first surface of the substrate;

a metal strip evenly attached to the laminating adhesive on the first surface of the substrate, the metal strip having a first connection region, a second connection region, and a fuse link therebetween having an upper surface and a side surface, the first connection region being disposed along substantially the full length of the first end of the first surface of the substrate, the second connection region being disposed along substantially the full length of the second end of the first surface of the substrate;

a first clip lead having at least one clip, each clip of the first clip lead having a mounting portion and a wrap-around portion, the wrap-around portion of each clip being aligned generally along the first connection region and first side of the substrate, and being conductively connected to the first connection region, wherein the wrap-around portion of each clip fastens the first clip lead to the substrate and first connection region, wherein the mounting portion of the first clip lead projects away from the first connection region; and

a second clip lead having at least one clip, each clip of the second clip lead having a mounting portion and a wrap-around portion, the wrap-around portion of each clip being aligned generally along the second connection region and second side of the substrate, and being conductively connected to the second connection region, wherein the wrap-around portion of each clip fastens the second clip lead to the substrate and second connection region, wherein the mounting portion of the second clip lead projects away from the second connection region, the first and second clip leads connecting the fuse to the remainder of the circuit.

29. The surface-mount fuse of claim 28, wherein a protective layer is disposed on the fuse link, the protective layer being in contact with and surrounding the upper and side surfaces of the fuse link of the metal strip.

30. The surface-mount fuse of claim 29, wherein the protective layer is also in contact with at least a fraction of the first and second connection regions of the metal strip.

31. The surface-mount fuse of claim 29, wherein said protective layer is made of a polymeric material.

32. The surface-mount fuse of claim 29, wherein the protective layer is made of an RTV silicone material.

33. The surface-mount fuse of claim 28, wherein the substrate is made of an FR-4 material.

34. The surface-mount fuse of claim 28, wherein the substrate is made of a melamine-based composition.

35. The surface-mount fuse of claim 34, wherein the melamine-based composition is a type G-5 melamine laminate.

36. The surface-mount fuse of claim 28, wherein a solder material is disposed between the first and second clip leads and the first and second connection regions, respectively, of the metal strip for conductively connecting the first and second clip leads to the first and second connection regions.

37. The surface-mount fuse of claim 28, wherein the metal strip is made from a zinc alloy.

38. The surface-mount fuse of claim 28, wherein the metal strip is made from a sheet of zinc foil.

39. The surface-mount fuse of claim 28, wherein the laminating adhesive is a silicone laminating adhesive.

40. A surface-mount fuse for protecting a circuit including the fuse comprising:

a substrate having first and second surfaces, each surface having first, second, third, and fourth ends, the substrate also having first, second, third, and fourth sides;

a laminating adhesive disposed on the first surface of the substrate;

a metal strip evenly attached to the first surface of the substrate by the laminating adhesive, wherein the metal strip has a first connection region, a second connection region, and a fuse link therebetween having an upper surface and a side surface, the first connection region being disposed along substantially the full length of the first end of the first surface of the substrate, the second connection region being disposed along substantially the full length of the second end of the first surface of the substrate;

a first terminal lead conductively connected to the first connection region; and

a second terminal lead conductively connected to the second connection region, the first and second terminal leads connecting the fuse to the remainder of the circuit.

41. The surface-mount fuse of claim 40, wherein the laminating adhesive is a silicone laminating adhesive.

42. The surface-mount fuse of claim 40, wherein the laminating adhesive is a blended silicone laminating adhesive.

43. The surface-mount fuse of claim 40, wherein the substrate is made of a type G-5 melamine laminate.