Patent US5092943A successfully refreshed from Google Patents.
US5092943A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Method of cleaning printed circuit boards using water
Assignee: Motorola Solutions Inc
•
Filing: 1990-09-17
•
Granted: 1992-03-03
•
Expires: 2010-09-17
Abstract
Abstract Solder pastes having vehicles including blends of low boiling point alcohols and relatively high boiling point alcohols are described which leave residues which may be cleaned using only water are described. The low boiling point alcohols have a boiling point range of between about 65° and about 150° C. whereas the high boiling point alcohols have a boiling point in rhe range of about 150° to about 270° C. The solder pastes also use water-soluble organic acids as fluxing agents such as compounds of the formula: ##STR1## where R is an electron withdrawing group such as fluorine, chlorine, bromine, iodine, sulfur, hydroxyl, nitrile, and benzyl. Other suitable formic-acid fluxing agents include, but are not limited to, adipic acid, polyacrylic acid, methacrylic acid and polymethacrylic acid. The compounds clean oxides from the printed circuit boards (PCBs) under assembly and then volatilze leaving a residue to be cleaned away. The cleaning step involves rinsing with water. No undesired residue remains indicating that the organic acids of the invention are effective in cleaning boards. Malic acid is a preferred organic acid fluxing agent.
Inventors
- 👤 James L. Davis
- 👤 Robert W. Pennisi
- 👤 Fadia Nounou
- 👤 Bobby D. Landreth
- 👤 Robert J. Mulligan
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-09 20:51
CPC Classifications
H; H05; H05K; H05K3/00; H05K3/30; H05K3/32; H05K3/34; H05K3/3489; B; B23; B23K; B23K35/00; B23K35/22; B23K35/36; B23K35/3612; B23K35/3618
Claims Analysis
Total Claims: 21
Claim 1
Independent Claim
183 words
A method of mounting electronic components on a printed circuit board providing a flux residue cleanable with water, comprising the steps of: formulating a solder paste by mixing together: a solder paste vehicle comprising: a fluxing agent comprising an organic acid having the formula: ##STR3## where R is an electron withdrawing group selected from the group consisting of fluorine, chlorine, bromine, iodine, sulfur, hydroxyl, nitrile, and benzyl; and a solvent blend selected from the group consisting of a blend of low boiling point alcohols having a boiling point in the range of about 65° to about 150° C. and high boiling point alcohols having a boiling point in the range of about 150° to about 270° C.; and a solder powder comprising a metal selected from the group consisting of lead, tin, antimony, silver and mixtures thereof; applying the solder paste to a metallic surface to be soldered; placing at least one electronic component on the metallic surface to be soldered; causing the solder paste to flow and form a solder bond; and removing the flux residue by washing the surface with water.
Claim 2
Independent Claim
183 words
A method of mounting electronic components on a printed circuit board providing a flux residue cleanable with water, comprising the steps of: formulating a solder paste by mixing together: a solder paste vehicle comprising: a fluxing agent comprising an organic acid having the formula: ##STR3## where R is an electron withdrawing group selected from the group consisting of fluorine, chlorine, bromine, iodine, sulfur, hydroxyl, nitrile, and benzyl; and a solvent blend selected from the group consisting of a blend of low boiling point alcohols having a boiling point in the range of about 65° to about 150° C. and high boiling point alcohols having a boiling point in the range of about 150° to about 270° C.; and a solder powder comprising a metal selected from the group consisting of lead, tin, antimony, silver and mixtures thereof; applying the solder paste to a metallic surface to be soldered; placing at least one electronic component on the metallic surface to be soldered; causing the solder paste to flow and form a solder bond; and removing the flux residue by washing the surface with water.
Claim 3
Dependent Claim
15 words
The method of claim 1 where the compound in the fluxing agent is malic acid.
Claim 4
Dependent Claim
43 words
The method of claim 1 where the solder paste comprises the following formulation: about 4 to about 10 wt. % solvent blend; about 2 to about 5 wt. % organic acid fluxing agent; and about 85 to about 94 wt. % solder powder.
Claim 5
Dependent Claim
17 words
The method of claim 3 where there is also present up to about 5 wt. % paraformaldehyde.
Claim 6
Dependent Claim
19 words
The method of claim 1 where both malic acid and polyacrylic acid are employed as organic acid fluxing agents.
Claim 7
Independent Claim
207 words
A method of mounting electronic components on a printed circuit board providing a flux residue cleanable with water, comprising the steps of: formulating a solder paste by mixing together: a solder paste vehicle comprising: a solvent blend selected from the group consisting of a blend of low boiling point alcohols having a boiling point in the range of about 65° to about 150° C. and high boiling point alcohols having a boiling point in the range of about 150° C. to about 270° C.; and a fluxing agent comprising an organic acid having the formula: ##STR4## where R is an electron withdrawing group selected from the group consisting of fluorine, chlorine, bromine, iodine, sulfur, hydroxyl, nitrile, and benzyl, and where the proportion of the organic acid in the vehicle ranges from about 0.1 to about 60 wt. % of the vehicle; and a solder powder comprising a metal selected from the group consisting of lead, tin, antimony, silver and mixtures thereof; applying the solder paste to a metallic surface to be soldered; placing at least one electronic component on the metallic surface to be soldered; causing the solder paste to flow and form a solder bond; and removing the flux residue by washing the surface with water.
Claim 8
Independent Claim
207 words
A method of mounting electronic components on a printed circuit board providing a flux residue cleanable with water, comprising the steps of: formulating a solder paste by mixing together: a solder paste vehicle comprising: a solvent blend selected from the group consisting of a blend of low boiling point alcohols having a boiling point in the range of about 65° to about 150° C. and high boiling point alcohols having a boiling point in the range of about 150° C. to about 270° C.; and a fluxing agent comprising an organic acid having the formula: ##STR4## where R is an electron withdrawing group selected from the group consisting of fluorine, chlorine, bromine, iodine, sulfur, hydroxyl, nitrile, and benzyl, and where the proportion of the organic acid in the vehicle ranges from about 0.1 to about 60 wt. % of the vehicle; and a solder powder comprising a metal selected from the group consisting of lead, tin, antimony, silver and mixtures thereof; applying the solder paste to a metallic surface to be soldered; placing at least one electronic component on the metallic surface to be soldered; causing the solder paste to flow and form a solder bond; and removing the flux residue by washing the surface with water.
Claim 9
Dependent Claim
15 words
The method of claim 6 where the compound in the fluxing agent is malic acid.
Claim 10
Dependent Claim
43 words
The method of claim 6 wherein the solder paste comprises the following formulation: about 4 to about 10 wt. % solvent blend; about 2 to about 5 wt. % organic acid fluxing agent; and about 85 to about 94 wt. % solder powder.
Claim 11
Dependent Claim
17 words
The method of claim 8 where there is also present up to about 5 wt. % paraformaldehyde.
Claim 12
Dependent Claim
19 words
The method of claim 6 where both malic acid and polyacrylic acid are employed as organic acid fluxing agents.
Claim 13
Independent Claim
262 words
A method of mounting electronic components on a printed circuit board providing a flux residue cleanable with water, comprising the steps of: formulating a solder paste by mixing together; a solder paste vehicle comprising: a solvent blend selected from the group consisting of a blend of low boiling point alcohols having a boiling point in the range of about 65° to about 150° C. and high boiling point alcohols having a boiling point in the range of about 150° to about 270° C.; and a fluxing agent selected from the group consisting of an organic acid having the formula: ##STR5## where R is an electron withdrawing group selected from the group consisting of fluorine, chlorine, bromine, iodine, sulfur, hydroxyl, nitrile, and benzyl, and where the proportion of the organic acid in the vehicle ranges from about 0.1 to about 60 wt. % of the vehicle; and a solder powder comprising a metal selected from the group consisting of lead, tin, antimony, silver and mixtures thereof; where the solder paste comprises the following formulation: about 4 to about 10 wt. % solvent; about 2 to about 5 wt. % organic acid fluxing agent; about 85 to about 94 wt. % solder powder; about 0 to about 3 wt. % paraformaldehyde; applying the solder paste to a metallic surface to be soldered; placing at least one electronic component on the metallic surface to be soldered; causing the solder paste to flow and form a solder bond producing a residue on the metallic surface; and removing the flux residue by washing the surface with water.
Claim 14
Independent Claim
262 words
A method of mounting electronic components on a printed circuit board providing a flux residue cleanable with water, comprising the steps of: formulating a solder paste by mixing together; a solder paste vehicle comprising: a solvent blend selected from the group consisting of a blend of low boiling point alcohols having a boiling point in the range of about 65° to about 150° C. and high boiling point alcohols having a boiling point in the range of about 150° to about 270° C.; and a fluxing agent selected from the group consisting of an organic acid having the formula: ##STR5## where R is an electron withdrawing group selected from the group consisting of fluorine, chlorine, bromine, iodine, sulfur, hydroxyl, nitrile, and benzyl, and where the proportion of the organic acid in the vehicle ranges from about 0.1 to about 60 wt. % of the vehicle; and a solder powder comprising a metal selected from the group consisting of lead, tin, antimony, silver and mixtures thereof; where the solder paste comprises the following formulation: about 4 to about 10 wt. % solvent; about 2 to about 5 wt. % organic acid fluxing agent; about 85 to about 94 wt. % solder powder; about 0 to about 3 wt. % paraformaldehyde; applying the solder paste to a metallic surface to be soldered; placing at least one electronic component on the metallic surface to be soldered; causing the solder paste to flow and form a solder bond producing a residue on the metallic surface; and removing the flux residue by washing the surface with water.
Claim 15
Dependent Claim
15 words
The method of claim 11 where the compound in the fluxing agent is malic acid.
Claim 16
Dependent Claim
13 words
The method of claim 12 where the fluxing agent additionally comprises polyacrylic acid.
Claim 17
Dependent Claim
12 words
The method of claim 11 where the solder paste contains no halocarbons.
Claim 18
Dependent Claim
39 words
The method of claim 11 where the low boiling point alcohols have a molecular weight range from about 46 to about 130 and the high boiling point alcohols have a molecular weight range from about 60 to about 180.
Claim 19
Dependent Claim
29 words
The method of claim 1 where the fluxing agent is selected from the group consisting of adipic acid, acrylic acid, polyacrylic acid, methacrylic acid, polymethacrylic acid and mixtures thereof.
Claim 20
Dependent Claim
29 words
The method of claim 6 where the fluxing agent is selected from the group consisting of adipic acid, acrylic acid, polyacrylic acid, methacrylic acid, polymethacrylic acid and mixtures thereof.
Claim 21
Dependent Claim
28 words
The method claim 11 where the fluxing agent is selected from the group consisting of adipic acid, acrylic acid, polyacrylic acid, methacrylic acid, polymethacrylic acid and mixtures thereof.
References Cited (Backward Citations)
US2898255A
Cited
US3436278A
Cited
US3734791A
Cited
US3796610A
Cited
US4460414A
Cited
US4541876A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1995-03-03 | 1995-09-02 | 1996-03-03 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1999-03-03 | 1999-09-02 | 2000-03-03 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2003-03-03 | 2003-09-02 | 2004-03-03 | $7700.00 | Window Closed / Lapsed |