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US5008512A
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Method of laser bonding electrical members
Assignee: Microelectronics and Computer Technology Corp
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Filing: 1989-09-08
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Granted: 1991-04-16
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Expires: 2009-09-08
Abstract
Abstract A method is disclosed for laser bonding two highly reflective electrical members. The first electrical member is coated with a material that is well absorbent of laser energy at the laser beam wavelength, has a lower melting point than either the first or second electrical members, and has a low solubility in a solid alloy of the electrical members. The laser characteristics are selected so that as bonding occurs an alloy of the electrical members solidifies and a solidification front drives the molten coating and molten compounds containing the coating away from the bond interface towards the exterior periphery of the bond, and substantially all of the solidified bond interface consists of an alloy of the first and second members. The coating can also aid in wetting the bond interface. In one example a copper electrical member coated with tin is bonded to a gold electrical member using a pulsed YAG laser with a beam diameter of 0.002 inches, a wavelength of 1.064 microns, an energy output of 1/4 to 1/2 joule, and a pulse time of 1 millisecond. Substantially all of the resulting bond interface consists of a copper/gold alloy without any tin intermetallics.
Inventors
- 👤 Phillip J. Spletter
- 👤 Colin A. MacKay
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-08 00:38
CPC Classifications
H; H10; H10W; H10W72/00; H10W72/071; H10W72/077; B; B23; B23K; B23K26/00; B23K26/18; H10W72/701
Claims Analysis
Total Claims: 18
Claim 1
Independent Claim
190 words
A method of bonding a first highly reflective metallic electrical member to a second highly reflective metallic electrical member by a laser comprising, coating the first electrical member with a material that is well absorbent to the laser energy at the wavelength of the laser, has a lower melting point than either of the electrical members, and has a low solubility in a solid alloy of the electrical members, aligning the first and second electrical members with the coating therebetween, holding the first and second electrical members in contact with the coating to form an interface, and bonding the first and second members at the interface by applying a laser beam, wherein the laser characteristics are selected so that as an alloy of the electrical members solidifies a solidification front will drive the molten coating and molten compounds containing the coating away from the bond interface towards the exterior periphery of the bond, wherein substantially all of the solidified bond interface consists of an alloy of the first and second members, and wherein substantially all of the bond interface strength results from an alloy of the first and second members.
Claim 2
Independent Claim
190 words
A method of bonding a first highly reflective metallic electrical member to a second highly reflective metallic electrical member by a laser comprising, coating the first electrical member with a material that is well absorbent to the laser energy at the wavelength of the laser, has a lower melting point than either of the electrical members, and has a low solubility in a solid alloy of the electrical members, aligning the first and second electrical members with the coating therebetween, holding the first and second electrical members in contact with the coating to form an interface, and bonding the first and second members at the interface by applying a laser beam, wherein the laser characteristics are selected so that as an alloy of the electrical members solidifies a solidification front will drive the molten coating and molten compounds containing the coating away from the bond interface towards the exterior periphery of the bond, wherein substantially all of the solidified bond interface consists of an alloy of the first and second members, and wherein substantially all of the bond interface strength results from an alloy of the first and second members.
Claim 3
Dependent Claim
11 words
The method of claim 1 wherein the laser beam is pulsed.
Claim 4
Dependent Claim
12 words
The method of claim 2 wherein the laser is a YAG laser.
Claim 5
Dependent Claim
14 words
The method of claim 3 wherein the laser beam wavelength is approximately 1.064 microns.
Claim 6
Dependent Claim
16 words
The method of claim 3 wherein the laser beam has a diameter of approximately 0.002 inches.
Claim 7
Dependent Claim
23 words
The method of claim 3 wherein the laser beam has an energy output of approximately 1/8 to 1/2 joule at the bond site.
Claim 8
Dependent Claim
19 words
The method of claim 3 wherein the laser beam has a pulse time of approximately one to two milliseconds.
Claim 9
Dependent Claim
20 words
The method of claim 1 wherein the coating material is selected from the group consisting of tin, indium, and gallium.
Claim 10
Dependent Claim
23 words
The method of claim 1 wherein the coating material is selected from a mixture of the group consisting of tin, indium, and gallium.
Claim 11
Dependent Claim
19 words
The method of claim 1 wherein the first electrical member is copper and the second electrical member is gold.
Claim 12
Dependent Claim
16 words
The method of claim 1 wherein the coating has the property of wetting the bond interface.
Claim 13
Independent Claim
159 words
A method of bonding a first electrical member containing a high degree of copper to a second electrical member containing a high degree of gold by a pulsed YAG laser comprising, coating the first electrical member with a material containing a high degree of tin, aligning the first and second electrical members with the coating therebetween, holding the first and second electrical members in contact with the coating to form an interface, and bonding the first and second members together at the interface by applying a laser beam, wherein the laser characteristics are selected so that as a copper/gold alloy solidifies a solidification front will drive the molten tin and molten compounds containing tin away from the bond interface towards the exterior periphery of the bond, wherein substantially all of the solidified bond interface consists of a copper/gold alloy, and wherein substantially all of the bond interface strength results from a copper/gold alloy of the first and second members.
Claim 14
Independent Claim
159 words
A method of bonding a first electrical member containing a high degree of copper to a second electrical member containing a high degree of gold by a pulsed YAG laser comprising, coating the first electrical member with a material containing a high degree of tin, aligning the first and second electrical members with the coating therebetween, holding the first and second electrical members in contact with the coating to form an interface, and bonding the first and second members together at the interface by applying a laser beam, wherein the laser characteristics are selected so that as a copper/gold alloy solidifies a solidification front will drive the molten tin and molten compounds containing tin away from the bond interface towards the exterior periphery of the bond, wherein substantially all of the solidified bond interface consists of a copper/gold alloy, and wherein substantially all of the bond interface strength results from a copper/gold alloy of the first and second members.
Claim 15
Dependent Claim
41 words
The method of claim 12 wherein the laser beam has a diameter of approximately 0.002 inches, a wavelength of approximately 1.064 microns, an energy output of approximately 1/8 to 1/2 joule, and a pulse time of approximately one to two milliseconds.
Claim 16
Dependent Claim
15 words
The method of claim 13 wherein the coating material is at least three micro-inches thick.
Claim 17
Dependent Claim
15 words
The method of claim 13 wherein the coating material is at least twelve micro-inches thick.
Claim 18
Dependent Claim
16 words
The method of claim 13 wherein the copper/gold alloy contains approximately 20% copper and 80% gold.
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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) | 1994-04-15 | 1994-10-15 | 1995-04-16 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1998-04-15 | 1998-10-15 | 1999-04-16 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2002-04-15 | 2002-10-15 | 2003-04-16 | $7700.00 | Window Closed / Lapsed |