US4494104A
Expired / Lapsed
US
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Thermal Fuse
Assignee: Nortel Networks Ltd
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Filing: 1983-07-18
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Granted: 1985-01-15
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Expires: 2003-07-18
Abstract
Abstract A fuse for responding to external temperatures to interrupt an electrical circuit, for example for interrupting a telephone battery feed in response to the temperature of a battery feed resistor, comprises a substrate carrying a pair of electrodes defining a gap between them. A fuse link, for example a gold strip, extends across the gap to interconnect the electrodes electrically. A film of solder overlies the fuse link and overlaps at least partly at least one of the electrodes. The fuse link is soluble in the molten solder so when the temperature of the solder paste exceeds its melting point, it melts, dissolves the fuse link, and retreats from the gap to sever the electrical connection between the electrodes. The fuse and a resistor whose temperature is to be detected, may be provided on a single substrate.
Inventors
- 👤 Edward S. B. Holmes
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-02 16:48
CPC Classifications
H; H01; H01H; H01H85/00; H01H85/02; H01H85/04; H01H85/041; H01H85/046; H01H37/00; H01H37/74; H01H37/76; H01H37/761; H01H37/02; H01H37/04; H01H2037/046; H01H2037/768
Claims Analysis
Total Claims: 13
Claim 1
Independent Claim
107 words
A fuse comprising: (i) a substrate; (ii) a pair of electrodes disposed upon the substrate and spaced apart to define a gap between them; (iii) a fuse link extending across said gap in intimate relationship with the substrate and interconnecting said electrodes electrically; (iv) a film of solder intimately overlying said fuse link and at least part of at least one of said electrodes, the solder, when molten, being capable of dissolving said fuse link; the arrangement being such that when its melting point is exceeded the solder will melt, dissolve the fuse link and retreat from the gap thereby severing the electrical connection between the electrodes.
Claim 2
Dependent Claim
107 words
A fuse comprising: (i) a substrate; (ii) a pair of electrodes disposed upon the substrate and spaced apart to define a gap between them; (iii) a fuse link extending across said gap in intimate relationship with the substrate and interconnecting said electrodes electrically; (iv) a film of solder intimately overlying said fuse link and at least part of at least one of said electrodes, the solder, when molten, being capable of dissolving said fuse link; the arrangement being such that when its melting point is exceeded the solder will melt, dissolve the fuse link and retreat from the gap thereby severing the electrical connection between the electrodes.
Claim 3
Dependent Claim
98 words
A fuse comprising: (i) a substrate; (ii) a pair of electrodes disposed upon the substrate and spaced apart to define a gap between them; (iii) a fuse link extending across said gap and interconnecting said electrodes electrically; (iv) a film of solder overlying said fuse link and at least part of each of said electrodes, the solder, when molten, being capable of dissolving said fuse link; the arrangement being such that when its melting point is exceeded the solder will melt, dissolve the fuse link and retreat from the gap thereby severing the electrical connection between the electrodes.
Claim 4
Dependent Claim
98 words
A fuse comprising: (i) a substrate; (ii) a pair of electrodes disposed upon the substrate and spaced apart to define a gap between them; (iii) a fuse link extending across said gap and interconnecting said electrodes electrically; (iv) a film of solder overlying said fuse link and at least part of each of said electrodes, the solder, when molten, being capable of dissolving said fuse link; the arrangement being such that when its melting point is exceeded the solder will melt, dissolve the fuse link and retreat from the gap thereby severing the electrical connection between the electrodes.
Claim 5
Dependent Claim
22 words
A fuse as defined in claim 1, wherein said fuse link is made of gold and said solder comprises a tin/lead solder.
Claim 6
Dependent Claim
14 words
A fuse as defined in claim 1, wherein said substrate is of ceramic material.
Claim 7
Dependent Claim
19 words
A fuse as defined in claim 1, including flux overlying at least said part of each of said electrodes.
Claim 8
Dependent Claim
14 words
A fuse as defined in claim 1, wherein said film comprises solder and flux.
Claim 9
Dependent Claim
19 words
A fuse as defined in claim 1 or 2, wherein said film overlies at least part of each electrode.
Claim 10
Dependent Claim
28 words
A fuse as defined in claim 1 or 2, mounted with a resistor on a common support, the fuse and resistor being interconnected electrically and in thermal communication.
Claim 11
Dependent Claim
38 words
A fuse as defined in claim 8, mounted on one side of the support, the resistor provided on the other side of the support in substantial alignment therewith, said resistor being connected electrically in series with said fuse.
Claim 12
Dependent Claim
22 words
A fuse as defined in claim 8, wherein said resistor and said fuse are provided on the same side of said support.
Claim 13
Dependent Claim
14 words
A fuse as defined in claim 8, wherein said resistor is a film resistor.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1988-01-15 | 1988-07-16 | 1989-01-15 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1992-01-15 | 1992-07-16 | 1993-01-15 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1996-01-15 | 1996-07-16 | 1997-01-15 | $7700.00 | Window Closed / Lapsed |