Patent US5728285A successfully refreshed from Google Patents.
US5728285A
Expired / Lapsed
US
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Protective coating combination for lead frames
Assignee: National Semiconductor Corp
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Filing: 1997-03-31
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Granted: 1998-03-17
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Expires: 2017-03-31
Abstract
Abstract A lead frame for a semiconductor device includes a base which is coated by a protective coating. The lead frame base is made of a ferrous material. The protective coating is made by sequentially electroplating a copper-containing layer, a silver-containing layer and a palladium-containing layer. Protective coatings constructed in this way are bondable, solderable, oxidation resistant, corrosion resistant, free of lead (Pb), resistant to high temperatures, cost effective, and cosmetically acceptable. It is also possible to use a layer of tin or a tin alloy in place of the silver layer.
Inventors
- 👤 Ranjan J. Mathew
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-07 12:45
CPC Classifications
H; H10; H10W; H10W70/00; H10W70/40; H10W70/456; H10W70/457; H10W72/00; H10W72/071; H10W72/075; H10W72/90; H10W72/951; H10W72/952; H10W90/00; H10W90/701; H10W90/751; H10W90/756
Claims Analysis
Total Claims: 2
Claim 1
Independent Claim
54 words
A method of fabricating a protective coating for a lead frame comprising the steps of: supplying a lead frame base consisting essentially of iron or an iron alloy; electroplating a copper-containing layer over the lead frame base; electroplating a silver-containing layer over the copper-containing layer; and electroplating a palladium-containing layer over the silver-containing layer.
Claim 2
Independent Claim
54 words
A method of fabricating a protective coating for a lead frame comprising the steps of: supplying a lead frame base consisting essentially of iron or an iron alloy; electroplating a copper-containing layer over the lead frame base; electroplating a silver-containing layer over the copper-containing layer; and electroplating a palladium-containing layer over the silver-containing layer.
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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) | 2001-03-16 | 2001-09-15 | 2002-03-17 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2005-03-16 | 2005-09-15 | 2006-03-17 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2009-03-16 | 2009-09-15 | 2010-03-17 | $7700.00 | Window Closed / Lapsed |