US5407121A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Fluxless soldering of copper
Assignee: RTI International
•
Filing: 1993-11-19
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Granted: 1995-04-18
•
Expires: 2013-11-19
Abstract
Abstract A method of soldering a copper layer without the use of fluxing agents by exposing the copper layer to a fluorine-containing plasma. Solder is then placed onto the surface of the copper layer and reflowed. Reflow can take place at low temperatures, atmospheric pressure and in an inert or oxidizing atmosphere using standard solder reflow equipment.
Inventors
- 👤 Nicholas G. Koopman
- 👤 Sundeep Nangalia
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-02 08:29
CPC Classifications
B; B23; B23K; B23K35/00; B23K35/22; B23K35/38; B23K1/00; B23K1/20; B23K2101/00; B23K2101/36; H; H05; H05K; H05K3/00; H05K3/30; H05K3/32; H05K3/34; H05K3/3489
Claims Analysis
Total Claims: 26
Claim 1
Independent Claim
40 words
A method of soldering a copper layer without the need for fluxing agents, comprising the steps of: exposing a copper layer having a copper surface to a fluorine-containing plasma; and placing solder on the copper surface of said copper layer.
Claim 2
Independent Claim
40 words
A method of soldering a copper layer without the need for fluxing agents, comprising the steps of: exposing a copper layer having a copper surface to a fluorine-containing plasma; and placing solder on the copper surface of said copper layer.
Claim 3
Dependent Claim
31 words
The method of claim 1 wherein said copper surface has a surface oxide layer, and wherein said exposing step converts at least a portion of the surface oxides to fluorine-containing compounds.
Claim 4
Dependent Claim
26 words
The method of claim 2 wherein said exposing step is performed until sufficient fluorine-containing compounds form on said copper surface to permit solder wetting to occur.
Claim 5
Dependent Claim
24 words
The method of claim 2 wherein said exposing step results in a fluorine/oxygen ratio on said copper surface of about 2/1 to about 8/1.
Claim 6
Dependent Claim
37 words
The method of claim 1 wherein the following step is performed between said exposing step and said placing step: storing the exposed copper layer in an air ambient for a period of up to about one week.
Claim 7
Dependent Claim
37 words
The method of claim 1 wherein the following step is performed between said exposing step and said placing step: storing the exposed copper layer in an inert ambient for a period of up to about two weeks.
Claim 8
Dependent Claim
24 words
The method of claim 1 further comprising the step of reflowing said solder on the surface of said copper layer after said placing step.
Claim 9
Dependent Claim
13 words
The method of claim 7 wherein said reflowing step occurs at atmospheric pressure.
Claim 10
Dependent Claim
13 words
The method claim 7 wherein said reflowing step occurs in an oxidizing ambient.
Claim 11
Dependent Claim
14 words
The method of claim 7 wherein said reflowing step occurs in an inert ambient.
Claim 12
Dependent Claim
37 words
The method of claim 7 wherein said reflowing step comprises placing said solder in contact with a second surface to thereby solder join together said copper surface and said second surface without the need for post-soldering cleaning.
Claim 13
Independent Claim
67 words
A method of soldering a copper layer without the need for fluxing agents, comprising the steps of: exposing a copper layer having a copper surface to a fluorine-containing plasma at a pressure from 400 mtorr to 800 mtorr and at a temperature from 20° C. to 120° C. for a period of 15 to 30 minutes; and placing solder on the copper surface of said copper layer.
Claim 14
Independent Claim
67 words
A method of soldering a copper layer without the need for fluxing agents, comprising the steps of: exposing a copper layer having a copper surface to a fluorine-containing plasma at a pressure from 400 mtorr to 800 mtorr and at a temperature from 20° C. to 120° C. for a period of 15 to 30 minutes; and placing solder on the copper surface of said copper layer.
Claim 15
Dependent Claim
24 words
The method of claim 12 wherein said exposing step results in a fluorine/oxygen ratio on said copper surface of about 2/1 to about 8/1.
Claim 16
Dependent Claim
37 words
The method of claim 12 wherein the following step is performed between said exposing step and said placing step: storing the exposed copper layer in an air ambient for a period of up to about one week.
Claim 17
Dependent Claim
37 words
The method of claim 12 wherein the following step is performed between said exposing step and said placing step: storing the exposed copper layer in an inert ambient for a period of up to about two weeks.
Claim 18
Dependent Claim
20 words
The method of claim 12 further comprising the step of reflowing said solder on the surface of said copper layer.
Claim 19
Dependent Claim
19 words
The method of claim 16 wherein said reflowing step occurs at a temperature of 200° C. to 220° C.
Claim 20
Dependent Claim
13 words
The method of claim 16 wherein said reflowing step occurs at atmospheric pressure.
Claim 21
Dependent Claim
13 words
The method claim 16 wherein said reflowing step occurs in an oxidizing ambient.
Claim 22
Dependent Claim
14 words
The method of claim 16 wherein said reflowing step occurs in an inert ambient.
Claim 23
Dependent Claim
37 words
The method of claim 16 wherein said reflowing step comprises placing said solder in contact with a second surface to thereby solder join together said copper surface and said second surface without the need for post-soldering cleaning.
Claim 24
Independent Claim
110 words
A method of soldering a copper layer without the need for fluxing agents, comprising the steps of: exposing a copper layer having a copper surface to a fluorine-containing plasma at a pressure from 400 mtorr to 800 mtorr and at a temperature from 20° C. to 120° C. for a period of 15 to 30 minutes so that a fluorine/oxygen ratio on said copper surface of about 2/1 to about 8/1 results; placing solder on the copper surface of said copper layer; and reflowing said solder on the copper surface of said copper layer at a temperature of 200° C. to 220° C. at atmospheric pressure in an oxidizing ambient.
Claim 25
Independent Claim
110 words
A method of soldering a copper layer without the need for fluxing agents, comprising the steps of: exposing a copper layer having a copper surface to a fluorine-containing plasma at a pressure from 400 mtorr to 800 mtorr and at a temperature from 20° C. to 120° C. for a period of 15 to 30 minutes so that a fluorine/oxygen ratio on said copper surface of about 2/1 to about 8/1 results; placing solder on the copper surface of said copper layer; and reflowing said solder on the copper surface of said copper layer at a temperature of 200° C. to 220° C. at atmospheric pressure in an oxidizing ambient.
Claim 26
Dependent Claim
37 words
The method of claim 22 wherein said reflowing step comprises placing said solder in contact with a second surface to thereby solder join together said copper surface and said second surface without the need for post-soldering cleaning.
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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) | 1998-04-17 | 1998-10-17 | 1999-04-18 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2002-04-17 | 2002-10-17 | 2003-04-18 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2006-04-17 | 2006-10-17 | 2007-04-18 | $7700.00 | Window Closed / Lapsed |