Thermally decoupling fuse holder and assembly

• US 7,564,337 B2
• Filed: 03/03/2005
• Issued: 07/21/2009
• Est. Priority Date: 03/03/2005
• Status: Active Grant

• Current Assignee: Littelfuse Incorporated
• Original Assignee: Littelfuse Incorporated
• Inventors: Whitney, Stephen J., Tran, Vincent Minh-Tu, Dietsch, Gordon T.
• Primary Examiner(s): Vortman; Anatoly
• Application Number:
  US11/072,553
• Publication Number:
  US 20060197647A1
• Time in Patent Office: 1,601 Days
• Field of Search: 337/297, 337/187, 337/251, 337/268, 337/269, 439/250, 439/830, 439/890, 439/849, 439/850
• US Class Current: 337/268
• CPC Class Codes: H01H 2085/0414 Surface mounted fuses
• CPC Class Codes: H01H 2085/2085 Holders for mounting a fuse on a printed circuit
• CPC Class Codes: H01H 85/0418 with ferrule type end contacts
• CPC Class Codes: H01H 85/202 for fuses with ferrule type end contacts
• CPC Class Codes: H05K 2201/062 Means for thermal insulation, e.g. for protection of parts
• CPC Class Codes: H05K 2201/10181 Fuse
• CPC Class Codes: H05K 2201/1031 Surface mounted metallic connector elements
• CPC Class Codes: H05K 2201/10386 Clip leads; Terminals gripping the edge of a substrate
• CPC Class Codes: H05K 2201/10636 Leadless chip, e.g. chip capacitor or resistor
• CPC Class Codes: H05K 2201/10757 Bent leads
• CPC Class Codes: H05K 2201/10946 Leads attached onto leadless component after manufacturing the component
• CPC Class Codes: H05K 3/301 by means of a mounting structure H05K3/325 takes precedence
• 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

In one aspect of the present invention, subminiature fuses are soldered to a PCB via clips attached to the fuse end caps. The clips are physically attached to the PCB pads, enabling the fuse to be replaced if needed and providing thermal decoupling between the fuse and the heating sinking solder/PCB pads. The fuse and clips can also be picked and placed in one operation. In another aspect, improved fuse clips are provided that include tabs that separate the housing portions of the clips from the heating sinking solder/PCB pads. Such improved clips further enhance thermal decoupling. In a further aspect, an improved fuse is provided, in which the thermal decoupling tabs just described are provided directly with the fuse. In yet a further aspect, a thermally insultive fuse body is provided to further decouple the fuse element from its surroundings.

Claims

1. A printed circuit board (“

PCB”

) fuse assembly comprising.

a first housing portion configured to hold a first terminal of a fuse, the first housing portion including a bottom wall, side walls, and a rear wall;

a first tab extending downwardly from the rear wall of the first housing portion, the first tab soldered to the PCB via a first solder joint andhaving a length such that the first housing portion is spaced apart from the PCB;

a second housing portion configured to hold a second terminal of the fuse, the second housing portion including a bottom wall, side walls, and a rear wall; and

a second tab extending downwardly from the rear wall of the second housing portion, the second tab soldered to the PCB via a second joint and having a length such that the second housing portion is spaced apart from the PCB.

2. The PCB fuse assembly of claim 1, wherein the length of the first tab is substantially the same as the length of the second tab.

3. The PCB fuse assembly of claim 1, which includes a fuse held by the first and second housing portions.

4. The PCB fuse assembly of claim 1, wherein the fuse is of a type selected from the group consisting of:

midget, 2AG, 3AG, 3AB, 5×

20 mm, Nano²®

, Pico®

SMF and chip fuses.

5. The PCB fuse assembly of claim 1, wherein the first and second tabs are soldered to the PCB via a process selected from the group consisting of:

wave soldering and reflow soldering.

6. The PCB fuse assembly of claim 1, wherein the first and second tabs are formed integrally with the first and second housing portions, respectively.

7. The PCB fuse assembly of claim 1, wherein the first and second tabs are connected to the first and second housing portions, respectively.

8. The PCB fuse assembly of claim 1, wherein the housing portions and the tabs are made of a material selected from the group consisting of a conductive material, ceramic, glass, polymer, brass, spring brass, copper, beryllium-copper, phosphor-bronze, steel, nickel, nickel alloy, tin, tin-lead, silver, gold, palladium, palladium alloy and rhodium.

9. The PCB fuse assembly of claim 1, wherein the PCB is made of a material selected from the group consisting of FR-4 material, ceramic, flexible material, cross-linked material, glass-epoxy composite, ceramic, and polymer material.

10. The PCB fuse assembly of claim 1, wherein the first and second housing portions are spaced apart on the .PCB a distance corresponding to at least one of a length of the fuse and the length of the tabs.

11. The PCB assembly of claim 1, wherein the first and second tabs are spaced apart on the PCB according to a distance that a plurality of conductive pads on the PCB are spaced apart.

12. The PCB fuse assembly of claim 1, wherein the rear walls corresponding to the first and second housing portions each include an indent extending inwardly from the rear walls.

13. The PCB fuse assembly of claim 1, wherein the rear walls and the side walls corresponding to the first and second housing portions each include an indent extending inwardly, and the bottom wails each include an indent extending upwardly.