US5447577A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Carbon dioxide-based fluxing media for non-VOC, no-clean soldering
Assignee: Visteon Global Technologies Inc
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Filing: 1994-10-24
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Granted: 1995-09-05
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Expires: 2014-10-24
Abstract
Abstract A flux formulation for use in the assembly of electronic circuit boards having components to be joined by soldering. The formulation comprises a medium which acts as a carrier and solvent for the fluxing agent, which includes in a preferred embodiment supercritical carbon dioxide. The formulation also includes a fluxing agent, being at least partially soluble in the supercritical carbon dioxide which serves to transport the fluxing agent before deposition thereof upon a soldering site. The supercritical fluid is delivered through a nozzle to the circuit board, the supercritical condition being maintained until the supercritical fluid is discharged from the nozzle. The fluxing agent at least partially loses its solubility in the fluid thereupon and is transported to the board by a stream of carbon dioxide gas. Also disclosed is a method for delivering a flux formulation to the electronic circuit board.
Inventors
- 👤 Guilian Gao
- 👤 Lakhi N. Goenka
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-09 17:57
CPC Classifications
B; B23; B23K; B23K35/00; B23K35/22; B23K35/36; B23K35/3612; B23K35/3618; B23K35/38; H; H05; H05K; H05K3/00; H05K3/30; H05K3/32; H05K3/34; H05K3/3489
Claims Analysis
Total Claims: 22
Claim 1
Independent Claim
63 words
A flux formulation for use in the assembly of electronic circuit boards, the formulation comprising: a medium which acts as a carrier and as a solvent, the medium including supercritical carbon dioxide; and a fluxing agent, the fluxing agent being at least partially soluble in the supercritical carbon dioxide which serves to transport the fluxing agent before deposition thereof upon a soldering site.
Claim 2
Dependent Claim
63 words
A flux formulation for use in the assembly of electronic circuit boards, the formulation comprising: a medium which acts as a carrier and as a solvent, the medium including supercritical carbon dioxide; and a fluxing agent, the fluxing agent being at least partially soluble in the supercritical carbon dioxide which serves to transport the fluxing agent before deposition thereof upon a soldering site.
Claim 3
Dependent Claim
13 words
The flux formulation of claim 1, wherein the fluxing agent comprises adipic acid.
Claim 4
Dependent Claim
17 words
The flux formulation of claim 1, wherein the fluxing agent comprises one or more weak organic acids.
Claim 5
Dependent Claim
13 words
The flux formulation of claim 1, wherein the fluxing agent comprises a rosin.
Claim 6
Dependent Claim
42 words
The flux formulation of claim 1, further comprising: a co-solvent having a high solubility for the fluxing agent and being miscible with carbon dioxide, the co-solvent being added to enhance the solubility of the fluxing agent and facilitating flux deposition after discharge.
Claim 7
Dependent Claim
25 words
The flux formulation of claim 5, wherein the co-solvent includes a material selected from the group consisting of methanol, ethanol, acetone, water, and mixtures thereof.
Claim 8
Dependent Claim
25 words
The flux formulation of claim 1, wherein the fluxing agent is a water solution of adipic acid with a solid content of up to 62.5%.
Claim 9
Dependent Claim
49 words
A flux formulation for use in the assembly of electronic circuit boards, the formulation comprising: a carrier, the carrier including carbon dioxide; and a flux solution comprising a fluxing agent and a solvent, the flux solution serving to transport the fluxing agent before deposition thereof upon a soldering site.
Claim 10
Dependent Claim
49 words
A flux formulation for use in the assembly of electronic circuit boards, the formulation comprising: a carrier, the carrier including carbon dioxide; and a flux solution comprising a fluxing agent and a solvent, the flux solution serving to transport the fluxing agent before deposition thereof upon a soldering site.
Claim 11
Independent Claim
131 words
A method for delivering a flux formulation to an electronic circuit board having components to be joined by soldering, comprising: adding a fluxing agent into a mixing vessel; introducing carbon dioxide into the mixing vessel, the carbon dioxide and the fluxing agent becoming intermixed and dissolved to form a fluid; heating the mixing vessel and the fluid to a temperature greater than 30 degrees Centigrade and pressurizing it to a pressure above 1050 psi to form a supercritical fluid; delivering the supercritical fluid through a nozzle to the circuit board, a supercritical condition being maintained until the supercritical fluid is discharged from the nozzle, the fluxing agent at least partially losing its solubility in the supercritical fluid thereupon and being transported to the board by a stream of carbon dioxide gas.
Claim 12
Independent Claim
131 words
A method for delivering a flux formulation to an electronic circuit board having components to be joined by soldering, comprising: adding a fluxing agent into a mixing vessel; introducing carbon dioxide into the mixing vessel, the carbon dioxide and the fluxing agent becoming intermixed and dissolved to form a fluid; heating the mixing vessel and the fluid to a temperature greater than 30 degrees Centigrade and pressurizing it to a pressure above 1050 psi to form a supercritical fluid; delivering the supercritical fluid through a nozzle to the circuit board, a supercritical condition being maintained until the supercritical fluid is discharged from the nozzle, the fluxing agent at least partially losing its solubility in the supercritical fluid thereupon and being transported to the board by a stream of carbon dioxide gas.
Claim 13
Dependent Claim
34 words
The method of claim 9, further comprising: providing a means for pressurizing in communication with the mixing vessel to increase the partial pressure of the carbon dioxide therewithin during introduction thereof into the vessel.
Claim 14
Dependent Claim
29 words
The method of claim 9, further comprising a means for stirring disposed within the mixing vessel to facilitate mixing and dissolution of the fluxing agent within the carbon dioxide.
Claim 15
Dependent Claim
18 words
The method of claim 11, wherein the step of adding a fluxing agent comprises adding 1-5% adipic acid.
Claim 16
Dependent Claim
17 words
The method of claim 12, further comprising the step of adding up to 5% of a co-solvent.
Claim 17
Dependent Claim
24 words
The method of claim 13, wherein the co-solvent comprises a material selected from the group consisting of methanol, ethanol, acetone, water, and mixtures thereof.
Claim 18
Independent Claim
111 words
A method for delivering a flux formulation to an electronic circuit board having components to be joined by soldering, comprising: heating a fluxing agent and water to a temperature up to 100° C. to form a flux solution in a closed supply vessel to minimize water loss by evaporation; providing carbon dioxide in a low pressure state; delivering the flux solution through a conduit to a nozzle so that flux temperature is preserved; communicating the carbon dioxide as a stream separate from the flux solution to the nozzle so that mixing is achieved substantially within the nozzle to form a fluxing mixture; and spraying the fluxing mixture onto the circuit board.
Claim 19
Independent Claim
111 words
A method for delivering a flux formulation to an electronic circuit board having components to be joined by soldering, comprising: heating a fluxing agent and water to a temperature up to 100° C. to form a flux solution in a closed supply vessel to minimize water loss by evaporation; providing carbon dioxide in a low pressure state; delivering the flux solution through a conduit to a nozzle so that flux temperature is preserved; communicating the carbon dioxide as a stream separate from the flux solution to the nozzle so that mixing is achieved substantially within the nozzle to form a fluxing mixture; and spraying the fluxing mixture onto the circuit board.
Claim 20
Dependent Claim
28 words
The method of claim 15, wherein the step of providing carbon dioxide in a low pressure state comprises providing carbon dioxide at a pressure up to 100 psi.
Claim 21
Dependent Claim
43 words
The method of claim 15, further comprising providing means for adjusting the streams of carbon dioxide and the fluxing agent entering the nozzle so that the ratio of the streams, the rate of spray, and the rate of flux consumption can be controlled.
Claim 22
Dependent Claim
16 words
The method of claim 15, wherein the flux solution comprises 1-62.5% adipic acid and 99-37.5% water.
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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) | 1998-09-04 | 1999-03-06 | 1999-09-05 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2002-09-04 | 2003-03-06 | 2003-09-05 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2006-09-04 | 2007-03-06 | 2007-09-05 | $7700.00 | Window Closed / Lapsed |