US4907734A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Method of bonding gold or gold alloy wire to lead tin solder
Assignee: International Business Machines Corp
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Filing: 1988-10-28
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Granted: 1990-03-13
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Expires: 2008-10-28
Abstract
Abstract A compression bond is formed between a gold or gold alloy wire and lead/tin solder by forming a head on the wire and forcing the head into a pad of the solder by thermosonic, or thermocompression, or ultrasonic compression bonding techniques. This forms a gold/tin intermetallic compound which in turn forms the bond. The head of the wire is maintained out of contact with any underlying surface, and surrounded by the solder.
Inventors
- 👤 H. Ward Conru
- 👤 Stephen E. Gons
- 👤 Gordon C. Osborne, Jr.
- 👤 Douglas W. Phelps, Jr.
- 👤 Stephen G. Starr
- 👤 William C. Ward
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-31 22:46
CPC Classifications
B; B23; B23K; B23K20/00; B23K20/02; B23K20/023; B23K20/10; B23K20/22; B23K35/00; B23K35/001; B23K35/007; H; H01; H01R; H01R43/00; H01R43/02; H10; H10W; H10W72/00; H10W72/01; H10W72/019; H01R4/00; H01R4/02; H01R4/023; H01R4/024; H05; H05K; H05K3/00; H05K3/30; H05K3/32; H05K3/328; H05K3/34; H05K3/3465; H10W72/071; H10W72/0711; H10W72/07141; H10W72/075; H10W72/07531; H10W72/07532; H10W72/07533; H10W72/07536; H10W72/07551; H10W72/07555; H10W72/50; H10W72/521; H10W72/522; H10W72/531; H10W72/536; H10W72/551; H10W72/552; H10W72/5522; H10W72/5524; H10W72/5525; H10W72/5528; H10W72/555; H10W72/59; H10W72/90; H10W72/931; H10W72/951; H10W72/952
Claims Analysis
Total Claims: 13
Claim 1
Independent Claim
129 words
A method of bonding gold or gold alloy wire to lead/tin solder overlying an underlying surface, comprising the steps of: forming said wire with an end portion having a composition of at least 50% gold, maintaining said solder at a temperature below the melting point of the lowest melting eutectic of said solder; and compression bonding said end portion of said wire to said solder, said bonding being characterized by said end portion of said wire being forced into said solder a distance sufficient to imbed a substantial portion of said end portion in said solder, but said end portion remaining out of contact with said underlying surface; whereby a gold/tin intermetallic compound is formed between at least part of said end portion of said wire and said solder.
Claim 2
Independent Claim
129 words
A method of bonding gold or gold alloy wire to lead/tin solder overlying an underlying surface, comprising the steps of: forming said wire with an end portion having a composition of at least 50% gold, maintaining said solder at a temperature below the melting point of the lowest melting eutectic of said solder; and compression bonding said end portion of said wire to said solder, said bonding being characterized by said end portion of said wire being forced into said solder a distance sufficient to imbed a substantial portion of said end portion in said solder, but said end portion remaining out of contact with said underlying surface; whereby a gold/tin intermetallic compound is formed between at least part of said end portion of said wire and said solder.
Claim 3
Dependent Claim
14 words
The invention as defined in claim 1 wherein the wire is a gold wire.
Claim 4
Dependent Claim
25 words
The invention as defined in claim 1 wherein the wire is a gold clad copper wire, wherein the gold constitutes at least 50% by weight.
Claim 5
Dependent Claim
19 words
The invention as defined in claim 1 wherein the end portion of the wire is formed into a ball.
Claim 6
Dependent Claim
17 words
The invention as defined in claim 1 wherein the solder is approximately 95% lead and 5% tin.
Claim 7
Dependent Claim
13 words
The invention as defined in claim 1 wherein the bonding is ultrasonic bonding.
Claim 8
Dependent Claim
13 words
The invention as defined in claim 1 wherein the bonding is thermosonic bonding.
Claim 9
Dependent Claim
13 words
The invention as defined in claim 1 wherein the bonding is thermocompression bonding.
Claim 10
Dependent Claim
18 words
The invention as defined in claim 1 wherein said underlying surface is a pedestal on a semiconductor chip.
Claim 11
Dependent Claim
15 words
The invention as defined in claim 9 wherein the pedestal is comprised of Al/Cr/Cu/Au layers.
Claim 12
Dependent Claim
22 words
The invention as defined in claim 1 wherein said end portion of said wire is a ball formed of a copper/gold alloy.
Claim 13
Dependent Claim
49 words
The invention as defined in claim 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, or 11 characterized by a further step, following said compression bonding, of heating said bonded wire and solder to a temperature below the melting point of the lowest melting eutectic of said solder.
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) | 1993-03-12 | 1993-09-11 | 1994-03-13 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1997-03-12 | 1997-09-11 | 1998-03-13 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2001-03-12 | 2001-09-11 | 2002-03-13 | $7700.00 | Window Closed / Lapsed |