US3750277A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Method of making lead frames for semiconductor devices
Assignee: Texas Instruments Inc
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Filing: 1970-10-23
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Granted: 1973-08-07
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Expires: 1990-10-23
Abstract
Abstract A method of producing lead frames for semiconductor devices in which a sheet of conductive material is initially removed by chemical or electrochemical milling to produce a substantially stress-free reduced thickness portion therein. A lead frame is then stamped from the sheet having lead fingers with substantially stress-free ends which are formed from the thinner material of the reduced thickness portion.
Inventors
- 👤 M Happ
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-25 18:30
CPC Classifications
H; H10; H10W; H10W70/00; H10W70/01; H10W70/04; Y; Y10; Y10T; Y10T29/00; Y10T29/49; Y10T29/49002; Y10T29/49117; Y10T29/49121
Claims Analysis
Total Claims: 8
Claim 1
Independent Claim
31 words
The method set forth in claim 1 wherein the surface atoms of the sheet of conductive material are oxidized by electrochemical exchange of electrons with ionic components of the said solution.
Claim 2
Dependent Claim
30 words
The method set forth in claim 1 wherein the surface atoms of the sheet of conductive material are oxidized by chemical exchange of electrons with ionic components of said solution.
Claim 3
Dependent Claim
53 words
The method set forth in claim 1 wherein a layer of a metal compatible with the semiconductor device is applied to a surface of the sheet and metallurgically bonded thereto, said layer being of such dimensions and so located as to cover the reduced thickness portion from which said free ends are formed.
Claim 4
Dependent Claim
25 words
The method set forth in claim 4 wherein said layer of metal is applied to the surface of the sheet prior to the removal step.
Claim 5
Dependent Claim
46 words
The method set forth in claim 4 wherein said sheet is an elongate strip, said layer of metal is applied in the form of a stripe extending longitudinally of said strip, and a series of reduced thickness portions are produced in the strip at intervals therealong.
Claim 6
Dependent Claim
21 words
The method set forth in claim 4 wherein said layer of metal compatible with a semiconductor device comprises aluminum or gold.
Claim 7
Dependent Claim
92 words
The method set forth in claim 2 wherein the concavity is produced by: bringing an electrode into close proximity with the portion of the surface of the sheet to be removed; flowing said solution in the gap between the electrode and the sheet; and electrically connecting the positive terminal of a direct current power source to the sheet and electrically connecting the negative terminal of said power source to said electrode thereby to oxidize a quantity of the conductive material and produce a reduced thickness portion of the sheet adjacent the electrode.
Claim 8
Dependent Claim
87 words
The method set forth in claim 3 wherein the said solution is an etch for the conductive material and the concavity is produced by applying an etch to a selected area of the surface of said sheet of conductive material for a time sufficient to oxidize and dissolve a quantity of said conductive material and produce a concavity in the surface of the sheet; removing said etch containing dissolved conductive material from contact with said sheet; and rinsing said concavity to remove residual etch from contact therewith.
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) | 1976-08-06 | 1977-02-05 | 1977-08-07 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1980-08-06 | 1981-02-05 | 1981-08-07 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1984-08-06 | 1985-02-05 | 1985-08-07 | $7700.00 | Window Closed / Lapsed |