US5650661A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Protective coating combination for lead frames
Assignee: National Semiconductor Corp
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Filing: 1995-04-27
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Granted: 1997-07-22
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Expires: 2015-04-27
Abstract
Abstract A lead frame for a semiconductor device includes a base layer which is coated by a protective coating. The protective coating includes a layer of nickel, over which is coated a layer of copper. The layer of copper is coated by a layer of silver over which is coated a layer of palladium. 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. It is possible to omit the nickel layer if the lead base layer is made of a ferrous material.
Inventors
- 👤 Ranjan J. Mathew
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-04 10:54
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; Y; Y10; Y10S; Y10S428/00; Y10S428/922; Y10S428/9265; Y10S428/929; Y10T; Y10T428/00; Y10T428/12; Y10T428/12493; Y10T428/12771; Y10T428/12861; Y10T428/12875; Y10T428/12896; Y10T428/12903; Y10T428/1291
Claims Analysis
Total Claims: 33
Claim 1
Independent Claim
47 words
A protective coating for a lead frame, the protective coating comprising: a lead frame; a nickel layer disposed over the lead frame; a copper-containing layer disposed over the nickel layer; a tin-containing layer disposed over the copper-containing layer; and a palladium layer disposed over the tin-containing layer.
Claim 2
Dependent Claim
47 words
A protective coating for a lead frame, the protective coating comprising: a lead frame; a nickel layer disposed over the lead frame; a copper-containing layer disposed over the nickel layer; a tin-containing layer disposed over the copper-containing layer; and a palladium layer disposed over the tin-containing layer.
Claim 3
Dependent Claim
13 words
The protective coating of claim 1 wherein the copper-containing layer consists of copper.
Claim 4
Dependent Claim
14 words
The protective coating of claim 1 wherein the copper-containing layer comprises a copper alloy.
Claim 5
Dependent Claim
13 words
The protective coating of claim 1 wherein the tin-containing layer consists of tin.
Claim 6
Dependent Claim
14 words
The protective coating of claim 1 wherein the tin-containing layer comprises a tin alloy.
Claim 7
Dependent Claim
13 words
The protective coating of claim 1 wherein the palladium layer consists of palladium.
Claim 8
Dependent Claim
14 words
The protective coating of claim 1 wherein the palladium layer comprises a palladium alloy.
Claim 9
Dependent Claim
26 words
The protective coating of claim 1 wherein the tin-containing layer has a thickness of at least 0.5 microns greater than the thickness of the copper-containing layer.
Claim 10
Dependent Claim
18 words
The protective coating of claim 1 wherein the lead frame consists essentially of copper or a copper alloy.
Claim 11
Dependent Claim
18 words
The protective coating of claim 1 wherein the lead frame consists essentially of iron or an iron alloy.
Claim 12
Dependent Claim
93 words
A protective coating for a lead frame, the protective coating comprising: a lead frame; a nickel layer disposed over the lead frame; a copper-containing layer disposed over the nickel layer; a tin-containing layer disposed over the copper-containing layer; and a palladium layer disposed over the tin-containing layer; wherein the nickel layer is between 0.2 and 2.50 microns in thickness, the copper-containing layer is between 0.08 and 1.5 microns in thickness, the tin-containing layer is between 0.5 and 5.0 microns in thickness, and the palladium-containing layer is between 0.08 and 0.63 microns in thickness.
Claim 13
Dependent Claim
93 words
A protective coating for a lead frame, the protective coating comprising: a lead frame; a nickel layer disposed over the lead frame; a copper-containing layer disposed over the nickel layer; a tin-containing layer disposed over the copper-containing layer; and a palladium layer disposed over the tin-containing layer; wherein the nickel layer is between 0.2 and 2.50 microns in thickness, the copper-containing layer is between 0.08 and 1.5 microns in thickness, the tin-containing layer is between 0.5 and 5.0 microns in thickness, and the palladium-containing layer is between 0.08 and 0.63 microns in thickness.
Claim 14
Dependent Claim
39 words
A protective coating for a lead frame, the protective coating comprising: a lead frame; a nickel layer disposed over the lead frame; a tin-containing layer disposed over the nickel layer; and a palladium layer disposed over the tin-containing layer.
Claim 15
Dependent Claim
39 words
A protective coating for a lead frame, the protective coating comprising: a lead frame; a nickel layer disposed over the lead frame; a tin-containing layer disposed over the nickel layer; and a palladium layer disposed over the tin-containing layer.
Claim 16
Dependent Claim
13 words
The protective coating of claim 12 wherein the tin-containing layer consists of tin.
Claim 17
Dependent Claim
14 words
The protective coating of claim 12 wherein the tin-containing layer comprises a tin alloy.
Claim 18
Dependent Claim
13 words
The protective coating of claim 12 wherein the palladium layer consists of palladium.
Claim 19
Dependent Claim
14 words
The protective coating of claim 12 wherein the palladium layer comprises a palladium alloy.
Claim 20
Dependent Claim
18 words
The protective coating of claim 12 wherein the lead frame consists essentially of copper or a copper alloy.
Claim 21
Dependent Claim
18 words
The protective coating of claim 12 wherein the lead frame consists essentially of iron or an iron alloy.
Claim 22
Dependent Claim
47 words
A protective coating for a lead frame, the protective coating comprising: a lead frame consisting essentially of iron or an iron alloy; a copper-containing layer disposed over the lead frame; a silver-containing layer disposed over the copper-containing layer; and a palladium-containing layer disposed over the silver-containing layer.
Claim 23
Dependent Claim
47 words
A protective coating for a lead frame, the protective coating comprising: a lead frame consisting essentially of iron or an iron alloy; a copper-containing layer disposed over the lead frame; a silver-containing layer disposed over the copper-containing layer; and a palladium-containing layer disposed over the silver-containing layer.
Claim 24
Dependent Claim
47 words
A protective coating for a lead frame, the protective coating comprising: a lead frame consisting essentially of iron or an iron alloy; a copper-containing layer disposed over the lead frame; a tin-containing layer disposed over the copper-containing layer; and a palladium-containing layer disposed over the tin-containing layer.
Claim 25
Dependent Claim
47 words
A protective coating for a lead frame, the protective coating comprising: a lead frame consisting essentially of iron or an iron alloy; a copper-containing layer disposed over the lead frame; a tin-containing layer disposed over the copper-containing layer; and a palladium-containing layer disposed over the tin-containing layer.
Claim 26
Dependent Claim
47 words
A protective coating for a lead frame, the protective coating comprising: a lead frame; a nickel-containing layer disposed over said lead frame; a copper-containing layer disposed over said nickel-containing layer; a silver-containing layer disposed over said copper-containing layer; and a palladium-containing layer disposed over said silver-containing layer.
Claim 27
Dependent Claim
47 words
A protective coating for a lead frame, the protective coating comprising: a lead frame; a nickel-containing layer disposed over said lead frame; a copper-containing layer disposed over said nickel-containing layer; a silver-containing layer disposed over said copper-containing layer; and a palladium-containing layer disposed over said silver-containing layer.
Claim 28
Dependent Claim
14 words
The protective coating of claim 21 wherein said nickel-containing layer comprises a nickel alloy.
Claim 29
Dependent Claim
47 words
A protective coating for a lead frame, the protective coating comprising: a lead frame; a cobalt layer disposed over said lead frame; a copper-containing layer disposed over said cobalt layer; a silver-containing layer disposed over said copper-containing layer; and a palladium-containing layer disposed over said silver-containing layer.
Claim 30
Dependent Claim
47 words
A protective coating for a lead frame, the protective coating comprising: a lead frame; a cobalt layer disposed over said lead frame; a copper-containing layer disposed over said cobalt layer; a silver-containing layer disposed over said copper-containing layer; and a palladium-containing layer disposed over said silver-containing layer.
Claim 31
Dependent Claim
14 words
The protective coating of claim 23 wherein said cobalt layer consists essentially of cobalt.
Claim 32
Dependent Claim
14 words
The protective coating of claim 23 wherein said cobalt layer comprises a cobalt alloy.
Claim 33
Dependent Claim
14 words
The protective coating of claim 23 wherein said cobalt layer comprises a tin-cobalt alloy.
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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) | 2000-07-21 | 2001-01-20 | 2001-07-22 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2004-07-21 | 2005-01-20 | 2005-07-22 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2008-07-21 | 2009-01-20 | 2009-07-22 | $7700.00 | Window Closed / Lapsed |