US4601424A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Stripped gold plating process
Assignee: International Business Machines Corp
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Filing: 1985-05-17
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Granted: 1986-07-22
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Expires: 2005-05-17
Abstract
Abstract A method for fabricating metallurgical contacts is disclosed for making thermocompression bonds to a metallized ceramic substrate on which semiconductor chips are to be mounted and electrically contacted. The method comprises placing a nickel layer on the metallized portion of the substrate and then covering the nickel with an immersion layer of gold. The gold immersion layer is selectively removed from locations where thermocompression-bonded contacts are desired. Removal is accomplished by applying a chemical stripper. Heavy gold is electroplated on said locations and the assemblage is heat treated prior to placement of the thermocompression-bonded contacts.
Inventors
- 👤 Avinash S. Adwalpalker
- 👤 Joseph M. Harvilchuck
- 👤 Joseph R. Ranalli
- 👤 David W. Rich
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-26 19:22
CPC Classifications
C; C04; C04B; C04B41/00; C04B41/009; B; B23; B23K; B23K20/00; B23K20/22; B23K20/233; B23K35/00; B23K35/001; C04B41/45; C04B41/52; C04B41/80; C04B41/81; C04B41/89; H; H01; H01R; H01R43/00; H01R43/16; H05; H05K; H05K3/00; H05K3/22; H05K3/24; H10; H10W; H10W70/00; H10W70/01; H10W70/05; H10W70/099; C04B2111/00; C04B2111/00474; C04B2111/00844; H10W72/00; H10W72/50; H10W72/531; H10W72/536
Claims Analysis
Total Claims: 10
Claim 1
Independent Claim
36 words
The process comprising depositing nickel on a substrate, forming a thin layer of gold over said nickel, chemically stripping said gold layer, depositing thick gold over said nickel, and diffusing said thick gold into said nickel.
Claim 2
Dependent Claim
36 words
The process comprising depositing nickel on a substrate, forming a thin layer of gold over said nickel, chemically stripping said gold layer, depositing thick gold over said nickel, and diffusing said thick gold into said nickel.
Claim 3
Dependent Claim
21 words
The process defined in claim 1 wherein said thick gold diffusing step is done at a temperature of about 550° C.
Claim 4
Dependent Claim
14 words
The process as described in claim 1 wherein said substrate is a ceramic material.
Claim 5
Dependent Claim
20 words
The process as described in claim 3 and further including a heating step for diffusing said nickel into said substrate.
Claim 6
Dependent Claim
33 words
The process as described in claim 1 wherein said thin layer of gold is formed by an immersion process to a thickness in the range of about 700 Å to about 1200 Å.
Claim 7
Dependent Claim
21 words
The process as described in claim 1 and further including the step of thermocompression bonding an electrode to said thick gold.
Claim 8
Dependent Claim
68 words
The process comprising depositing nickel on a substrate, forming a thin layer of gold over said nickel, selectively placing a masking material to cover certain areas of said nickel, chemically stripping said gold layer from said unmasked areas, depositing thick gold over said unmasked areas of said nickel, removing said masking material, diffusing said thick gold into said nickel, and thermocompression bonding an electrode to said thick gold.
Claim 9
Dependent Claim
68 words
The process comprising depositing nickel on a substrate, forming a thin layer of gold over said nickel, selectively placing a masking material to cover certain areas of said nickel, chemically stripping said gold layer from said unmasked areas, depositing thick gold over said unmasked areas of said nickel, removing said masking material, diffusing said thick gold into said nickel, and thermocompression bonding an electrode to said thick gold.
Claim 10
Dependent Claim
22 words
The process as described in claim 7 wherein said thick gold diffusing step is done at a temperature of about 550° C.
References Cited (Backward Citations)
US3362851A
Cited
US3539390A
Cited
US3982908A
Cited
US4268849A
Cited
US4268584A
Cited
US4464420A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1989-07-21 | 1990-01-20 | 1990-07-22 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1993-07-21 | 1994-01-20 | 1994-07-22 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1997-07-21 | 1998-01-20 | 1998-07-22 | $7700.00 | Window Closed / Lapsed |