Patent US5757263A successfully refreshed from Google Patents.
US5757263A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Zinc phosphate coating for varistor
Assignee: Littelfuse Inc
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Filing: 1997-01-22
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Granted: 1998-05-26
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Expires: 2017-01-22
Abstract
Abstract Method of providing a semiconductor device with an inorganic electrically insulative layer, the device having exposed semiconductor surfaces and electrically conductive metal end terminations, in which the device is reacted with phosphoric acid to form a phosphate on the exposed surfaces of the semiconductor but not on the metal end terminations, and in which the device is thereafter barrel plated in a conventional electrical barrel plating process and the plating is provided only on the end terminations because the phosphate is not electrically conductive.
Inventors
- 👤 Palaniappan Ravindranathan
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-09 12:33
CPC Classifications
H; H01; H01C; H01C7/00; H01C7/18; H01C1/00; H01C1/02; H01C1/034; H01C7/10; H01C7/102
Claims Analysis
Total Claims: 13
Claim 1
Independent Claim
92 words
A nonlinear resistive element comprising: a body having stacked zinc oxide semiconductor layers; a generally planar electrode between each pair of said layers, each said electrode having a contactable portion that is exposed for electrical connection; plural spaced electrically conductive metal end terminations, each of said end terminations being on an end portion of said body for contacting at least one said contactable portion; an electrically insulative material substantially coating said body between said end terminations said material consisting substantially of zinc phosphate; and an electrically conductive metal coating said end terminations.
Claim 2
Dependent Claim
92 words
A nonlinear resistive element comprising: a body having stacked zinc oxide semiconductor layers; a generally planar electrode between each pair of said layers, each said electrode having a contactable portion that is exposed for electrical connection; plural spaced electrically conductive metal end terminations, each of said end terminations being on an end portion of said body for contacting at least one said contactable portion; an electrically insulative material substantially coating said body between said end terminations said material consisting substantially of zinc phosphate; and an electrically conductive metal coating said end terminations.
Claim 3
Dependent Claim
11 words
The element of claim 1 wherein said body comprises a varistor.
Claim 4
Dependent Claim
51 words
The element of claim 1 wherein the body comprises in mole percent, 94-98% zinc oxide and 2-6% of one or more of the additives selected from the group of additives consisting of bismuth oxide, cobalt oxide, manganese oxide, nickel oxide, antimony oxide, boric oxide, chromium oxide, silicon oxide, and aluminum nitrate.
Claim 5
Dependent Claim
14 words
The nonlinear resistive element of claim 1 wherein said electrically conductive metal comprises nickel.
Claim 6
Dependent Claim
14 words
The nonlinear resistive element of claim 1 wherein said electrically conductive metal comprises tin-lead.
Claim 7
Dependent Claim
27 words
The nonlinear resistive element of claim 1 wherein said electrically conductive metal end terminations comprise a metal selected from the group consisting of silver, silver-platinum, and silver-palladium.
Claim 8
Dependent Claim
41 words
A nonlinear resistive element comprising: a disc zinc oxide varistor; end terminations on opposing surfaces of said disc varistor for making electrical contact; and an electrically insulating layer consisting substantially of zinc phosphate covering said disc varistor, except said end terminations.
Claim 9
Dependent Claim
41 words
A nonlinear resistive element comprising: a disc zinc oxide varistor; end terminations on opposing surfaces of said disc varistor for making electrical contact; and an electrically insulating layer consisting substantially of zinc phosphate covering said disc varistor, except said end terminations.
Claim 10
Dependent Claim
17 words
The nonlinear resistive element of claim 7 further comprising an electrically conductive metal coating said end terminations.
Claim 11
Dependent Claim
14 words
The nonlinear resistive element of claim 8 wherein said electrically conductive metal comprises nickel.
Claim 12
Dependent Claim
14 words
The nonlinear resistive element of claim 8 wherein said electrically conductive metal comprises tin-lead.
Claim 13
Dependent Claim
26 words
The nonlinear resistive element of claim 7 wherein said end terminations comprise a layer of metal selected from the group consisting of silver, silver-platinum, and silver-palladium.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 2001-05-25 | 2001-11-24 | 2002-05-26 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2005-05-25 | 2005-11-24 | 2006-05-26 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2009-05-25 | 2009-11-24 | 2010-05-26 | $7700.00 | Window Closed / Lapsed |