Patent US5186379A successfully refreshed from Google Patents.
US5186379A
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US
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Indium alloy cold weld bumps
Assignee: OL Security LLC
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Filing: 1992-06-25
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Granted: 1993-02-16
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Expires: 2012-06-25
Abstract
Abstract An improved method for indium bonding of surfaces comprising forming indium bumps on a first surface, such as a semiconductor chip. An alloying metal which forms a primary-intermetallic-free alloy with indium is provided on a second surface, such as a substrate to be connected to the pad of the semiconductor chip. The pad and substrate are cold welded at 2000 to 6000 pounds per square inch (1.0×10 5 to 3.1×10 5 mm Hg) to form indium alloy bonds having improved strength, reliability, and toughness.
Inventors
- 👤 Carlyle L. Helber, Jr.
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-10 02:21
CPC Classifications
H; H10; H10W; H10W72/00; H10W72/20; H10W72/251; H10W72/252
Claims Analysis
Total Claims: 16
Claim 1
Independent Claim
157 words
A method for indium bonding of surfaces comprising the steps of: (a) providing an indium bump on a first surface; (b) providing a second surface having an alloying metal located thereon wherein said alloying metal is capable of forming an alloy with indium when cold welded wherein said alloy is substantially free of a primary intermetallic phase; and (c) pressing said indium bump located on said first surface against said alloying metal located on said second surface at a pressure within the range of about 2000 to 6000 psi (1.0×10 5 to 3.1×10 5 mm Hg) at a temperature within the range of about 20° C. to 150° C. for a sufficient period of time to form said alloy of said indium and said alloying metal to thereby bond said indium bump to said second surface to provide a substantially durable cold weld electrical connection having a bond interface which is substantially free of primary intermetallic phase.
Claim 2
Independent Claim
157 words
A method for indium bonding of surfaces comprising the steps of: (a) providing an indium bump on a first surface; (b) providing a second surface having an alloying metal located thereon wherein said alloying metal is capable of forming an alloy with indium when cold welded wherein said alloy is substantially free of a primary intermetallic phase; and (c) pressing said indium bump located on said first surface against said alloying metal located on said second surface at a pressure within the range of about 2000 to 6000 psi (1.0×10 5 to 3.1×10 5 mm Hg) at a temperature within the range of about 20° C. to 150° C. for a sufficient period of time to form said alloy of said indium and said alloying metal to thereby bond said indium bump to said second surface to provide a substantially durable cold weld electrical connection having a bond interface which is substantially free of primary intermetallic phase.
Claim 3
Dependent Claim
23 words
The method of Claim 1 wherein said alloying metal is selected from the group consisting of elemental metals, metal alloys, and metal mixtures.
Claim 4
Dependent Claim
23 words
The method of Claim 2 wherein said elemental metal is selected from the group consisting of aluminum, cadmium, gallium, germanium, silicon, and zinc.
Claim 5
Dependent Claim
24 words
The method of Claim 2 wherein said alloying metal comprises indium bonded to a metal selected from the group consisting of said elemental metals.
Claim 6
Dependent Claim
21 words
The method of Claim 2 wherein said alloying metal comprises one or more metals bonded to a metal other than indium.
Claim 7
Dependent Claim
26 words
The method of Claim 1 wherein said alloying metal forms a secondary intermetallic phase with said indium which is substantially free of said primary intermetallic phase.
Claim 8
Dependent Claim
65 words
The method of Claim 1 wherein said alloying metal has the property of forming an unwanted surface oxide layer and said method further comprises, prior to said pressing, providing said alloying metal with a thin adherent coating of a chosen metal to control the formation of said surface oxide and to thereby enable the formation of said alloy of said indium and said alloying metal.
Claim 9
Dependent Claim
21 words
The method of Claim 7 wherein said chosen metal is selected from the group consisting of zinc, lead, cadmium, and tin.
Claim 10
Dependent Claim
44 words
The method of Claim 1 further comprising, after said pressing, heating to a temperature within the range of about 25° C. to 150° C. for about 1 to 120 hours to enhance the formation of said alloy of said indium and said alloying metal.
Claim 11
Dependent Claim
16 words
The method of Claim 1 wherein said first surface comprises a pad on a semiconductor chip.
Claim 12
Dependent Claim
19 words
The method of Claim 1 wherein said second surface is a substrate wherein said substrate has a bonding pad.
Claim 13
Dependent Claim
24 words
The method of Claim 1 wherein said alloying metal on said second surface is in the form of a bump on said second surface.
Claim 14
Dependent Claim
52 words
The method of Claim 1 wherein said alloying metal on said second surface is in the form of a smooth plane on said second surface, said smooth plane being parallel to a plane formed by said deposited indium on said first surface when said second surface is juxtaposed to said first surface.
Claim 15
Dependent Claim
13 words
The method of Claim 1 wherein said second surface comprises said alloying metal.
Claim 16
Dependent Claim
17 words
A device formed by the method of Claim 1 comprising a semiconductor chip connected to a substrate.
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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) | 1996-02-16 | 1996-08-17 | 1997-02-16 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2000-02-16 | 2000-08-17 | 2001-02-16 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2004-02-16 | 2004-08-17 | 2005-02-16 | $7700.00 | Window Closed / Lapsed |