US4372996A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Method for metallizing aluminum pads of an integrated circuit chip
Assignee: Massachusetts Institute of Technology
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Filing: 1979-09-07
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Granted: 1983-02-08
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Expires: 1999-09-07
Abstract
Abstract A method including a novel bath is described for the nickeling of the aluminum pads of a chip, when either in die form or in wafer assembly. A near-neutral pH immersion zinc bath is used to cover the aluminum with zinc, which is followed by immersion in an electroless boron-nickel solution for nickeling of the zinc. The method eliminates the need to isolate the chip silicon from the plating bath.
Inventors
- 👤 Elis A. Guditz
- 👤 Robert L. Burke
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-02 22:40
CPC Classifications
H; H10; H10W; H10W90/00; C; C23; C23C; C23C18/00; C23C18/16; C23C18/31; H10W70/00; H10W70/099; H10W70/60; H10W70/611; H10W70/614; H10W72/00; H10W72/01; H10W72/0198; H10W72/90; H10W72/941; H10W72/9413
Claims Analysis
Total Claims: 11
Claim 1
Independent Claim
41 words
An immersion zinc bath comprising, a solution containing the following components in suitable concentration for providing a bath for electroless immersion zinc metallization of aluminum, H 2 O, ZnSO 4 , HF, Citric acid, and NH 4 OH for near-neutral pH.
Claim 2
Dependent Claim
41 words
An immersion zinc bath comprising, a solution containing the following components in suitable concentration for providing a bath for electroless immersion zinc metallization of aluminum, H 2 O, ZnSO 4 , HF, Citric acid, and NH 4 OH for near-neutral pH.
Claim 3
Dependent Claim
55 words
The bath of claim 1 wherein the amount of the components of the bath are: a. 100 ml deionized H 2 O, b. 2 g. ZnSO 4 .7 H 2 O, c. 2.5 ml HF (48%), d. 1 g. Citric Acid, monohydrate, and, e. NH 4 OH necessary to achieve a bath of pH 7.3.
Claim 4
Dependent Claim
30 words
The method of zinc flashing on aluminum comprising the step of, immerse aluminum in the solution of claim 2 for a time sufficient to completely cover the aluminum with zinc.
Claim 5
Dependent Claim
23 words
The method of claim 3 wherein the immersion time is approximately 60 seconds and the temperature of the solution is approximately 32° C.
Claim 6
Dependent Claim
25 words
The method of claim 4 comprising in addition the step of, degreasing the aluminum prior to immersing the aluminum in the bath of claim 2.
Claim 7
Dependent Claim
30 words
The method of zinc flashing on aluminum comprising the step of, immerse aluminum in the solution of claim 1 for a time sufficient to completely cover the aluminum with zinc.
Claim 8
Dependent Claim
23 words
The method of claim 6 wherein the immersion time is approximately 60 seconds and the temperature of the solution is approximately 32° C.
Claim 9
Dependent Claim
25 words
The method of claim 7 comprising in addition the step of, degreasing the aluminum prior to immersing the aluminum in the bath of claim 1.
Claim 10
Independent Claim
79 words
A method for compounding an electroless immersion near-neutral pH zinc bath comprising: first dissolving ZnSO 4 in H 2 O to form a solution, then adding HF to said solution, then adding citric acid to said HF solution, then adding sufficient NH 4 OH to said citric acid solution to obtain a near-neutral pH, the concentrations of said ZnSO 4 , HF, and citric acid being such that the bath is suitable for electroless immersion zinc metallization of aluminum.
Claim 11
Independent Claim
79 words
A method for compounding an electroless immersion near-neutral pH zinc bath comprising: first dissolving ZnSO 4 in H 2 O to form a solution, then adding HF to said solution, then adding citric acid to said HF solution, then adding sufficient NH 4 OH to said citric acid solution to obtain a near-neutral pH, the concentrations of said ZnSO 4 , HF, and citric acid being such that the bath is suitable for electroless immersion zinc metallization of aluminum.
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) | 1986-02-07 | 1986-08-09 | 1987-02-08 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1990-02-07 | 1990-08-09 | 1991-02-08 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1994-02-07 | 1994-08-09 | 1995-02-08 | $7700.00 | Window Closed / Lapsed |