Method of manufacturing a surface-mounted fuse device

• US 5,943,764 A
• Filed: 06/07/1995
• Issued: 08/31/1999
• Est. Priority Date: 05/27/1994
• Status: Expired due to Term

• Current Assignee: Littelfuse Incorporated
• Original Assignee: Littelfuse Incorporated
• Inventors: Onken, Daniel B., Blecha, Vladimir, McGuire, Katherine M., Neuhalfen, Andrew J.
• Primary Examiner(s): ECHOLS, PERCY W
• Application Number:
  US08/482,829
• Time in Patent Office: 1,546 Days
• Field of Search: 29/623, 29/621, 29/619, 29/874, 427/282, 101/129, 337/222, 337/297
• US Class Current: 29/623
• CPC Class Codes: H01C 17/08 by vapour deposition
• CPC Class Codes: H01C 7/006 Thin film resistors
• CPC Class Codes: H01C 7/1013 Thin film varistors
• CPC Class Codes: H01C 7/12 Overvoltage protection resistors series resistors structurally associated with spark gaps H01T1/16
• CPC Class Codes: H01H 2085/0414 Surface mounted fuses
• 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 85/11 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: Y10T 29/49101 Applying terminal
• CPC Class Codes: Y10T 29/49107 Fuse making
• CPC Class Codes: Y10T 29/49204 Contact or terminal manufacturing

Abstract

A thin film surface-mount fuse having two material subassemblies. The first subassembly includes a fusible link, its supporting substrate and terminal pads. The second subassembly includes a protective layer which overlies the fusible link so as to provide protection from impacts and oxidation. The protective layer is preferably made of a polymeric material. The most preferred polymeric material is a polyurethane gel or paste. In addition, the most preferred supporting substrate is an FR-4 epoxy or a polyimide.

Claims

1. A method for the manufacture of a thin film surface-mount fuse comprising the steps of:

a. providing a substrate having a top, a bottom and opposing sides, the opposing sides each having a groove therein;

b. depositing, upon the top of the substrate, a first conductive layer to simultaneously form a fusible link and terminal pads at opposite ends of the fusible link, the fusible link and terminal pads being electrically connected; and

,

c. applying a protective layer, wherein the protective layer is a layer of polymeric material which is applied as a gel and is smoothed across the upper surface of the supporting substrate and the fuse link to provide the polymeric material with a substantially flat upper surface.

2. The method as set forth in claim 1, wherein the first conductive layer extends from the top of the substrate and is deposited upon a portion of the sides of the substrate so that the terminal pads extend from the top of the substrate to a portion of the sides of the substrate.

3. The method of claim 2, wherein the first conductive layer is deposited in the grooves of the sides of the substrate so that the terminal pads are in the grooves of the substrate.

4. The method of claim 2, wherein the first conductive layer extends from the sides of the substrate and is deposited on a portion of the bottom of the substrate so that the terminal pads extend onto a portion of the bottom of the substrate.

5. The method as set forth in claim 1, wherein the first conductive layer which forms said fusible link and terminal pads is deposited by vapor deposition.

6. The method as set forth in claim 1, wherein the first conductive layer which forms said fusible link and terminal pads is electrochemically deposited.

7. A method of manufacturing a thin film surface-mount fuse comprising the steps of:

a. providing a substrate having an upper surface, a lower surface and a pair of bores;

b. depositing a first conductive layer on the upper surface of the substrate to simultaneously form a fusible link and terminal pads on the upper surface of the substrate, the fusible link being deposited between the pair of bores and being electrically connected to the terminal pads; and

,

c. applying a protective layer, wherein the protective layer includes a single layer of polymeric material which is applied as a gel and is smoothed across the upper surface of the supporting substrate and the fuse link to provide a substantially flat upper surface when the polymeric material hardens.

8. The method of claim 7, wherein the first conductive layer extends from the upper surface of the substrate into the bores so that the terminal pads extend from the upper surface into the bores.

9. The method of claim 8, wherein the first conductive layer extends from the bores and terminates on the lower surface of the substrate so that the terminal pads extend from the bores and terminate on the lower surface of the substrate.

10. The method of claim 9, further including the step of depositing one or more additional conductive layers on top of the terminal pads.

11. The method of claim 7, further including the step of deposition a metallic spot onto the fusible link.

12. The method of claim 7, wherein the protective layer is applied to the fusible link using a stencil printing machine.