Patent US4020987A successfully refreshed from Google Patents.
US4020987A
Expired / Lapsed
US
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Solder preform for use in hermetically sealing a container
Assignee: Individual
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Filing: 1975-09-22
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Granted: 1977-05-03
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Expires: 1995-09-22
Abstract
Abstract A solder preform for hermetically sealing a cover to a container for a semiconductor package comprises a relatively thick flat ring of an alloy consisting of substantially 95% lead, 2.5% tin, and 2.5% silver, which alloy has the characteristic that it solidifies from the fluid state as a homogeneous mixture without substantial separation of the minority element crystals. The solder preform further comprises a relatively thin coating clad on each surface of the flat ring of an oxidation-resistant alloy, preferably an alloy consisting of substantially 96.5% tin and 3.5% silver.
Inventors
- 👤 Norman Hascoe
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-28 04:23
CPC Classifications
H; H10; H10W; H10W95/00; B; B23; B23K; B23K35/00; B23K35/02; B23K35/0222; B23K35/0233; B23K35/0238; Y; Y10; Y10T; Y10T428/00; Y10T428/12; Y10T428/12222; Y10T428/12361; Y10T428/12493; Y10T428/12701; Y10T428/12708
Claims Analysis
Total Claims: 4
Claim 1
Independent Claim
69 words
A solder preform for hermetically sealing a cover to a container for a semiconductor package comprising a relatively thick flat ring of an alloy consisting of 90-97% lead, 1-4% tin, and 1-4% silver and having the characteristic that it solidifies from the fluid state as a homogeneous mixture and a relatively thin coating clad on each surface thereof of an oxidation-resistant alloy consisting of 92-98% tin and 2-8% silver.
Claim 2
Dependent Claim
69 words
A solder preform for hermetically sealing a cover to a container for a semiconductor package comprising a relatively thick flat ring of an alloy consisting of 90-97% lead, 1-4% tin, and 1-4% silver and having the characteristic that it solidifies from the fluid state as a homogeneous mixture and a relatively thin coating clad on each surface thereof of an oxidation-resistant alloy consisting of 92-98% tin and 2-8% silver.
Claim 3
Dependent Claim
25 words
A solder preform in accordance with claim 1 in which said ring is an alloy consisting of substantially 95% lead, 2.5% tin, and 2.5% silver.
Claim 4
Dependent Claim
23 words
A solder preform in accordance with claim 1 in which said coating is an alloy consisting of substantially 96.5% tin and 3.5% silver.
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) | 1980-05-02 | 1980-11-01 | 1981-05-03 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1984-05-02 | 1984-11-01 | 1985-05-03 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1988-05-02 | 1988-11-01 | 1989-05-03 | $7700.00 | Window Closed / Lapsed |