CA2053759A1 - Water-soluble flux for cored solder - Google Patents
Water-soluble flux for cored solderInfo
- Publication number
- CA2053759A1 CA2053759A1 CA002053759A CA2053759A CA2053759A1 CA 2053759 A1 CA2053759 A1 CA 2053759A1 CA 002053759 A CA002053759 A CA 002053759A CA 2053759 A CA2053759 A CA 2053759A CA 2053759 A1 CA2053759 A1 CA 2053759A1
- Authority
- CA
- Canada
- Prior art keywords
- acid
- flux
- oil
- flux composition
- water
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Abandoned
Links
- 230000004907 flux Effects 0.000 title claims abstract description 48
- 229910000679 solder Inorganic materials 0.000 title claims abstract description 36
- KRKNYBCHXYNGOX-UHFFFAOYSA-N citric acid Chemical compound OC(=O)CC(O)(C(O)=O)CC(O)=O KRKNYBCHXYNGOX-UHFFFAOYSA-N 0.000 claims abstract description 63
- 150000007524 organic acids Chemical class 0.000 claims abstract description 9
- 235000015165 citric acid Nutrition 0.000 claims description 16
- 239000000203 mixture Substances 0.000 claims description 15
- 239000003995 emulsifying agent Substances 0.000 claims description 14
- 239000003921 oil Substances 0.000 claims description 14
- 235000019198 oils Nutrition 0.000 claims description 14
- 239000004094 surface-active agent Substances 0.000 claims description 7
- 125000002843 carboxylic acid group Chemical group 0.000 claims description 4
- 239000000243 solution Substances 0.000 claims description 4
- LFQSCWFLJHTTHZ-UHFFFAOYSA-N Ethanol Chemical compound CCO LFQSCWFLJHTTHZ-UHFFFAOYSA-N 0.000 claims description 3
- 235000019482 Palm oil Nutrition 0.000 claims description 3
- 235000019483 Peanut oil Nutrition 0.000 claims description 3
- 239000002253 acid Substances 0.000 claims description 3
- 150000001298 alcohols Chemical class 0.000 claims description 3
- 239000002540 palm oil Substances 0.000 claims description 3
- 239000000312 peanut oil Substances 0.000 claims description 3
- KDYFGRWQOYBRFD-UHFFFAOYSA-N succinic acid Chemical compound OC(=O)CCC(O)=O KDYFGRWQOYBRFD-UHFFFAOYSA-N 0.000 claims description 3
- BJEPYKJPYRNKOW-REOHCLBHSA-N (S)-malic acid Chemical compound OC(=O)[C@@H](O)CC(O)=O BJEPYKJPYRNKOW-REOHCLBHSA-N 0.000 claims description 2
- FEWJPZIEWOKRBE-JCYAYHJZSA-N Dextrotartaric acid Chemical compound OC(=O)[C@H](O)[C@@H](O)C(O)=O FEWJPZIEWOKRBE-JCYAYHJZSA-N 0.000 claims description 2
- IAYPIBMASNFSPL-UHFFFAOYSA-N Ethylene oxide Chemical compound C1CO1 IAYPIBMASNFSPL-UHFFFAOYSA-N 0.000 claims description 2
- WHUUTDBJXJRKMK-UHFFFAOYSA-N Glutamic acid Natural products OC(=O)C(N)CCC(O)=O WHUUTDBJXJRKMK-UHFFFAOYSA-N 0.000 claims description 2
- WHUUTDBJXJRKMK-VKHMYHEASA-N L-glutamic acid Chemical compound OC(=O)[C@@H](N)CCC(O)=O WHUUTDBJXJRKMK-VKHMYHEASA-N 0.000 claims description 2
- 239000004721 Polyphenylene oxide Substances 0.000 claims description 2
- 229920001213 Polysorbate 20 Polymers 0.000 claims description 2
- GOOHAUXETOMSMM-UHFFFAOYSA-N Propylene oxide Chemical compound CC1CO1 GOOHAUXETOMSMM-UHFFFAOYSA-N 0.000 claims description 2
- FEWJPZIEWOKRBE-UHFFFAOYSA-N Tartaric acid Natural products [H+].[H+].[O-]C(=O)C(O)C(O)C([O-])=O FEWJPZIEWOKRBE-UHFFFAOYSA-N 0.000 claims description 2
- 125000002877 alkyl aryl group Chemical group 0.000 claims description 2
- BJEPYKJPYRNKOW-UHFFFAOYSA-N alpha-hydroxysuccinic acid Natural products OC(=O)C(O)CC(O)=O BJEPYKJPYRNKOW-UHFFFAOYSA-N 0.000 claims description 2
- 125000000129 anionic group Chemical group 0.000 claims description 2
- 239000007864 aqueous solution Substances 0.000 claims description 2
- 125000002091 cationic group Chemical group 0.000 claims description 2
- 235000019441 ethanol Nutrition 0.000 claims description 2
- 239000004220 glutamic acid Substances 0.000 claims description 2
- 235000013922 glutamic acid Nutrition 0.000 claims description 2
- 150000002314 glycerols Chemical class 0.000 claims description 2
- 239000001630 malic acid Substances 0.000 claims description 2
- 235000011090 malic acid Nutrition 0.000 claims description 2
- 229920000570 polyether Polymers 0.000 claims description 2
- 239000000256 polyoxyethylene sorbitan monolaurate Substances 0.000 claims description 2
- 235000010486 polyoxyethylene sorbitan monolaurate Nutrition 0.000 claims description 2
- 239000000244 polyoxyethylene sorbitan monooleate Substances 0.000 claims description 2
- 235000010482 polyoxyethylene sorbitan monooleate Nutrition 0.000 claims description 2
- 239000000249 polyoxyethylene sorbitan monopalmitate Substances 0.000 claims description 2
- 235000010483 polyoxyethylene sorbitan monopalmitate Nutrition 0.000 claims description 2
- 239000001818 polyoxyethylene sorbitan monostearate Substances 0.000 claims description 2
- 235000010989 polyoxyethylene sorbitan monostearate Nutrition 0.000 claims description 2
- 229920000053 polysorbate 80 Polymers 0.000 claims description 2
- 235000002906 tartaric acid Nutrition 0.000 claims description 2
- 239000011975 tartaric acid Substances 0.000 claims description 2
- 229940119170 jojoba wax Drugs 0.000 claims 2
- XNGIFLGASWRNHJ-UHFFFAOYSA-N phthalic acid Chemical compound OC(=O)C1=CC=CC=C1C(O)=O XNGIFLGASWRNHJ-UHFFFAOYSA-N 0.000 claims 2
- ATJFFYVFTNAWJD-UHFFFAOYSA-N Tin Chemical compound [Sn] ATJFFYVFTNAWJD-UHFFFAOYSA-N 0.000 claims 1
- 239000003945 anionic surfactant Substances 0.000 claims 1
- 239000003093 cationic surfactant Substances 0.000 claims 1
- 239000002736 nonionic surfactant Substances 0.000 claims 1
- 239000001384 succinic acid Substances 0.000 claims 1
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 abstract description 11
- 231100000252 nontoxic Toxicity 0.000 abstract description 6
- 230000003000 nontoxic effect Effects 0.000 abstract description 6
- 239000002932 luster Substances 0.000 abstract description 3
- 230000009972 noncorrosive effect Effects 0.000 abstract description 3
- 229960004106 citric acid Drugs 0.000 description 15
- 238000005476 soldering Methods 0.000 description 15
- KFZMGEQAYNKOFK-UHFFFAOYSA-N Isopropanol Chemical compound CC(C)O KFZMGEQAYNKOFK-UHFFFAOYSA-N 0.000 description 8
- 239000000306 component Substances 0.000 description 6
- 238000000034 method Methods 0.000 description 5
- RSWGJHLUYNHPMX-UHFFFAOYSA-N Abietic-Saeure Natural products C12CCC(C(C)C)=CC2=CCC2C1(C)CCCC2(C)C(O)=O RSWGJHLUYNHPMX-UHFFFAOYSA-N 0.000 description 3
- KHPCPRHQVVSZAH-HUOMCSJISA-N Rosin Natural products O(C/C=C/c1ccccc1)[C@H]1[C@H](O)[C@@H](O)[C@@H](O)[C@@H](CO)O1 KHPCPRHQVVSZAH-HUOMCSJISA-N 0.000 description 3
- 239000008367 deionised water Substances 0.000 description 3
- 229910021641 deionized water Inorganic materials 0.000 description 3
- 230000007613 environmental effect Effects 0.000 description 3
- 229960004592 isopropanol Drugs 0.000 description 3
- 235000005985 organic acids Nutrition 0.000 description 3
- 230000008569 process Effects 0.000 description 3
- KHPCPRHQVVSZAH-UHFFFAOYSA-N trans-cinnamyl beta-D-glucopyranoside Natural products OC1C(O)C(O)C(CO)OC1OCC=CC1=CC=CC=C1 KHPCPRHQVVSZAH-UHFFFAOYSA-N 0.000 description 3
- CBENFWSGALASAD-UHFFFAOYSA-N Ozone Chemical compound [O-][O+]=O CBENFWSGALASAD-UHFFFAOYSA-N 0.000 description 2
- 238000004140 cleaning Methods 0.000 description 2
- 238000005238 degreasing Methods 0.000 description 2
- 230000036541 health Effects 0.000 description 2
- 239000002184 metal Substances 0.000 description 2
- 230000004048 modification Effects 0.000 description 2
- 238000012986 modification Methods 0.000 description 2
- 230000009467 reduction Effects 0.000 description 2
- 239000002904 solvent Substances 0.000 description 2
- 239000000126 substance Substances 0.000 description 2
- 239000002562 thickening agent Substances 0.000 description 2
- 239000012855 volatile organic compound Substances 0.000 description 2
- UOCLXMDMGBRAIB-UHFFFAOYSA-N 1,1,1-trichloroethane Chemical compound CC(Cl)(Cl)Cl UOCLXMDMGBRAIB-UHFFFAOYSA-N 0.000 description 1
- 235000019737 Animal fat Nutrition 0.000 description 1
- 206010013786 Dry skin Diseases 0.000 description 1
- 229910045601 alloy Inorganic materials 0.000 description 1
- 239000000956 alloy Substances 0.000 description 1
- 230000000712 assembly Effects 0.000 description 1
- 238000000429 assembly Methods 0.000 description 1
- 239000012298 atmosphere Substances 0.000 description 1
- KDYFGRWQOYBRFD-NUQCWPJISA-N butanedioic acid Chemical compound O[14C](=O)CC[14C](O)=O KDYFGRWQOYBRFD-NUQCWPJISA-N 0.000 description 1
- 239000003795 chemical substances by application Substances 0.000 description 1
- 230000007797 corrosion Effects 0.000 description 1
- 238000005260 corrosion Methods 0.000 description 1
- 239000013078 crystal Substances 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 239000012153 distilled water Substances 0.000 description 1
- 238000001035 drying Methods 0.000 description 1
- 239000003344 environmental pollutant Substances 0.000 description 1
- 238000009472 formulation Methods 0.000 description 1
- 239000008187 granular material Substances 0.000 description 1
- 239000012535 impurity Substances 0.000 description 1
- 238000004519 manufacturing process Methods 0.000 description 1
- 231100000989 no adverse effect Toxicity 0.000 description 1
- 239000000843 powder Substances 0.000 description 1
- 229920006395 saturated elastomer Polymers 0.000 description 1
- 239000000725 suspension Substances 0.000 description 1
- 238000009736 wetting Methods 0.000 description 1
Landscapes
- Colloid Chemistry (AREA)
- Electric Connection Of Electric Components To Printed Circuits (AREA)
Abstract
WATER-SOLUBLE FLUX FOR CORED SOLDER
ABSTRACT OF THE DISCLOSURE
A non-toxic, non-corrosive water-soluble flux for cored solders comprises (a) botanical oil, (b) an emulsifi-er, and (c) an organic acid, such as citric acid. The flux of the invention produces solder joints of high metallic luster and excellent quality. Clean-up of flux residues is accomplished using only water.
ABSTRACT OF THE DISCLOSURE
A non-toxic, non-corrosive water-soluble flux for cored solders comprises (a) botanical oil, (b) an emulsifi-er, and (c) an organic acid, such as citric acid. The flux of the invention produces solder joints of high metallic luster and excellent quality. Clean-up of flux residues is accomplished using only water.
Description
2~37~9 PATENT
WATER-SOLUBLE FLUX FOR CORED SOLDER
CROSS-REFERENCE TO RELATED APPLICATIONS
~he present application is a continuation-in-part ap~
plication of Serial No. 07/ , , filed [PD-89640A], which in turn is a continuation-in-part applica-tion of Serial No. 07/523,765, filed May 15, 1990, both ap-plications filed in the name of Ray L. Turner and assigned to the same assignee as the present application. The ap-plications disclose and claim a method of soldering using a water-soluble flux which co~tains a water-soluble organic acid having at least two carboxylic acid groups. A pre-ferred example of such an organic acid is citric acid.
The present application is also related to Serial No.
07/ ~ PD-90465] filed the same date as the present application and assigned ko the same assignee as the pres-ent application. That application discloses and claims a composition of matter useful as a solder paste and a method for using the same.
TEcHNIcAll FIE~D
The present invention relates to a novel water-solu-ble, environmentally-safe ~lux for cored solders, useful in electronic industry soldering processes.
BACKGROUND AR~
Most fluxe~ and defluxing chemicals used by industry to manufacture electronic circuits, such as military hard-ware, are either contributing to ozone depletion of the at-2~37~9 mosphere or are considered by local environmental agencies, such as the Air Quality Management District in the Los An~
geles basin, as environmental pollutants or health ha~ards.
For example, it has been reported that if CFCs (chlorofluo-rohydrocarbons), which are used in vapor degreasing to clean soldered parts where a rosin flux is employed, are releasad to the atmosphere, they will remain there as an ozone depletant for nearly 100 years. Other chemicals such as rosin fluxes, alcohols, and the like pose health risks and disposal problems for industry.
Water-soluble fluxes for cored solders are formula-tions that combine a soldering flux with a thickening agent maintained within a hollow tube of solder.
What is desired is a simple, non-toxic, non-corrosive, environmentally-safe solder flux for cored solclers that produces solder joints of high metallic luster and excel-lent quality.
DISCLOSURE OF INVENTION
In accordance with the invention, a water-soluble flux for cored solder is provided, comprising (a) botanical oil, (b) emulsifier, and (c~ a water-soluble organic acid having at least two carboxylic acid groups.
The flux of the invention eliminates harmful environ-mental emissions normally associated with rosin-~ased flux-es, flux thinner (such as iso-propanol), and associated de~
fluxing solvents (such as CFCs)~ The flux of the invention is environmentally safe, non-toxic, and easy to use. Sol-dering time is cut in half, and defluxing (cleaning) time is reduced from ten to fifteen minutes (required for rosin-based fluxes) to about three minutes. Soldered assemblies can be cleaned in deionized water, thus eliminating the high capital costs associated with vapor degreasing e~uip-ment. The resulting soldered joint exhibits high metallic luster and excellent electrical quality.
. .
- -~3~
BEST MODES FOR CARRYING OUT THE IMVENTION
The flux of the invention comprises (a) botanical oil, (b) emulsifier, and (c) a waker-soluble organic acid having at least two carboxylic acid groups. Examples of suitable organic acids include citric acid, malic acid, tartaric acid, glutamic acid, phthali~ acid, succinic acid, and the like.
However, the best results have been obtained with cit-ric acid, and while the class of organic acids indicatedabove is useful, the remainder of the description which follows is directed to the use of citric acid as a flux in cored solders used in soldering components.
Without subscribing to any particular theory, it ap-pears that the citric acid chelates the oxide of the basismetal, but not the metal itself. As a result, there is little or no corrosion of the basis metal by the flux of the invention. Thus, to the extent that members of the above class of organic acids behaves similarly to citric acid, then such members are also included within the ambit of the invention.
The botanical oil serves to level the solder, minimize splattering during the soldering process, and prevent dry-ing of the paste. The oil is used to assist in produ~ing a smooth solder surface. Examples of suitable botanical oils include ~ojoba oil, palm oil, and peanut oil. Animal fat oils do not clean up easily, and are to be avoided in the practice of the invention.
Any of the well-known water-soluble emulsifiers and surfactants of the cationic, anionic, and non-ionic type may be used in the practice of the invention to assure a reduction in surface tension, enhance solder spread, and aid in flux removal, and as used herein, the term "emulsi-fier" is intended to also include surfactants. One or more such emulsifiers and surfactants may be employed. Examples of suitable emulsifiers and surfactants include ethylene oxide and propylene oxide and adducts thereto, adducts of ' 2~375~
glycerol esters, polyoxyethylene sorbitan monopalmitate, polyoxyethylene sorbitan monolaurate, alkyl aryl polyether alcohol, polyoxyethylene sorbitan monooleate, polyoxyethyl-ene sorbitan monostearate, and ethoxylated linear alcohols.
5The emulsifier keeps the oil and water in suspension and can act as a thickening agent. The -Elux must be thin enough to be co-extruded with the solder, but thick enough so as not to exude. The viscosity range of fluxes employed in cored solders is well-known, and does not form a part of 10this invention.
An aqueous solution of citric acid is used. Tha cit-ric acid concentration may range from about 3 wt% to satu-ration of the total flux composition. ~he amount of water should be minimized to avoid splatter, and accordingly, a 15saturated solution of citric acid in water is preferably employed. In this connection, an amount of water suffi-cient to dissolve citric acid (powder, crystals, or gran-ules) is employed. The grade or class of the citric acid is not critical in the practice of the invention, nor is 20the type or purity of the water used. However, for ex-tremely sensitive electrical circuits, it may be desirable to employ distilled or deionized water and a fairly high grade oP citric acid.
Alternatively, a non-toxic medium which ties up free 25water may be used for lower concentrations of citric acld.
An ethoxylated linear alcohol may be used for this purpose.
The flux may contain other components, such as impuri-ties, whether accidental or deliberate, so long as such ad-ditives have no adverse effect on the soldering results.
30The ratio of emulsifier to citric acid solution is preferably about 1:1; the emulsifier is used to suspend the oil in the citric acid.
An especially preferred flux composition for cored solder consists essentially of the following:
35(1) about 1 to 5 wt% botanical oil;
(2) about 47.5 to 49.5 wt% emulsifier, and ' ` , ' '':: , ~: .
-2~375~
~3) about 47.5 to 49.5 wt% citric acid solution (3% to saturated).
Any of the common soldering alloys may be employed, including 60/40 Sn/Pb, 62/2/36 Sn/Ag/Pb, 63/37 Sn/Pb, and 96~4 Sn/Ag. Typically, 60/40 and 63/37 solders are used.
As is well-known, a hollow cylinder of the solder is co-extruded with the flux to form the composit~ cored solder.
Tha flux/cored solder is most advantageously employed in surface mount component soldering processes. The flux contains no volatile organic compounds (VOCs) or other evaporative solvents, such as iso-propyl alcohol. The wa-tar-soluble solder flux of the invention avoids tha use oE
rosin-cored solders, which necessitate the use of chloro-fluorocarbon-type defluxing agents; rather, the flux of the invention is ~asily defluxed using deionized water.
The flux of the invention provides the following ad-vantages:
1. It eliminates harmful environmental emissions normally associated with rosin-cored fluxes, flux thinner (such as iso-propyl alcohol), and associated defluxing ag~nts (such as 1,1,1-trichloroethane). Indeed, cleaning of the flux is simply done in warm or hot water. Thus, the new flux is environmentally safe.
2. It provides soldering personnel with a non toxic, extremely safe, and highly effective flux/cored sol-der to use.
WATER-SOLUBLE FLUX FOR CORED SOLDER
CROSS-REFERENCE TO RELATED APPLICATIONS
~he present application is a continuation-in-part ap~
plication of Serial No. 07/ , , filed [PD-89640A], which in turn is a continuation-in-part applica-tion of Serial No. 07/523,765, filed May 15, 1990, both ap-plications filed in the name of Ray L. Turner and assigned to the same assignee as the present application. The ap-plications disclose and claim a method of soldering using a water-soluble flux which co~tains a water-soluble organic acid having at least two carboxylic acid groups. A pre-ferred example of such an organic acid is citric acid.
The present application is also related to Serial No.
07/ ~ PD-90465] filed the same date as the present application and assigned ko the same assignee as the pres-ent application. That application discloses and claims a composition of matter useful as a solder paste and a method for using the same.
TEcHNIcAll FIE~D
The present invention relates to a novel water-solu-ble, environmentally-safe ~lux for cored solders, useful in electronic industry soldering processes.
BACKGROUND AR~
Most fluxe~ and defluxing chemicals used by industry to manufacture electronic circuits, such as military hard-ware, are either contributing to ozone depletion of the at-2~37~9 mosphere or are considered by local environmental agencies, such as the Air Quality Management District in the Los An~
geles basin, as environmental pollutants or health ha~ards.
For example, it has been reported that if CFCs (chlorofluo-rohydrocarbons), which are used in vapor degreasing to clean soldered parts where a rosin flux is employed, are releasad to the atmosphere, they will remain there as an ozone depletant for nearly 100 years. Other chemicals such as rosin fluxes, alcohols, and the like pose health risks and disposal problems for industry.
Water-soluble fluxes for cored solders are formula-tions that combine a soldering flux with a thickening agent maintained within a hollow tube of solder.
What is desired is a simple, non-toxic, non-corrosive, environmentally-safe solder flux for cored solclers that produces solder joints of high metallic luster and excel-lent quality.
DISCLOSURE OF INVENTION
In accordance with the invention, a water-soluble flux for cored solder is provided, comprising (a) botanical oil, (b) emulsifier, and (c~ a water-soluble organic acid having at least two carboxylic acid groups.
The flux of the invention eliminates harmful environ-mental emissions normally associated with rosin-~ased flux-es, flux thinner (such as iso-propanol), and associated de~
fluxing solvents (such as CFCs)~ The flux of the invention is environmentally safe, non-toxic, and easy to use. Sol-dering time is cut in half, and defluxing (cleaning) time is reduced from ten to fifteen minutes (required for rosin-based fluxes) to about three minutes. Soldered assemblies can be cleaned in deionized water, thus eliminating the high capital costs associated with vapor degreasing e~uip-ment. The resulting soldered joint exhibits high metallic luster and excellent electrical quality.
. .
- -~3~
BEST MODES FOR CARRYING OUT THE IMVENTION
The flux of the invention comprises (a) botanical oil, (b) emulsifier, and (c) a waker-soluble organic acid having at least two carboxylic acid groups. Examples of suitable organic acids include citric acid, malic acid, tartaric acid, glutamic acid, phthali~ acid, succinic acid, and the like.
However, the best results have been obtained with cit-ric acid, and while the class of organic acids indicatedabove is useful, the remainder of the description which follows is directed to the use of citric acid as a flux in cored solders used in soldering components.
Without subscribing to any particular theory, it ap-pears that the citric acid chelates the oxide of the basismetal, but not the metal itself. As a result, there is little or no corrosion of the basis metal by the flux of the invention. Thus, to the extent that members of the above class of organic acids behaves similarly to citric acid, then such members are also included within the ambit of the invention.
The botanical oil serves to level the solder, minimize splattering during the soldering process, and prevent dry-ing of the paste. The oil is used to assist in produ~ing a smooth solder surface. Examples of suitable botanical oils include ~ojoba oil, palm oil, and peanut oil. Animal fat oils do not clean up easily, and are to be avoided in the practice of the invention.
Any of the well-known water-soluble emulsifiers and surfactants of the cationic, anionic, and non-ionic type may be used in the practice of the invention to assure a reduction in surface tension, enhance solder spread, and aid in flux removal, and as used herein, the term "emulsi-fier" is intended to also include surfactants. One or more such emulsifiers and surfactants may be employed. Examples of suitable emulsifiers and surfactants include ethylene oxide and propylene oxide and adducts thereto, adducts of ' 2~375~
glycerol esters, polyoxyethylene sorbitan monopalmitate, polyoxyethylene sorbitan monolaurate, alkyl aryl polyether alcohol, polyoxyethylene sorbitan monooleate, polyoxyethyl-ene sorbitan monostearate, and ethoxylated linear alcohols.
5The emulsifier keeps the oil and water in suspension and can act as a thickening agent. The -Elux must be thin enough to be co-extruded with the solder, but thick enough so as not to exude. The viscosity range of fluxes employed in cored solders is well-known, and does not form a part of 10this invention.
An aqueous solution of citric acid is used. Tha cit-ric acid concentration may range from about 3 wt% to satu-ration of the total flux composition. ~he amount of water should be minimized to avoid splatter, and accordingly, a 15saturated solution of citric acid in water is preferably employed. In this connection, an amount of water suffi-cient to dissolve citric acid (powder, crystals, or gran-ules) is employed. The grade or class of the citric acid is not critical in the practice of the invention, nor is 20the type or purity of the water used. However, for ex-tremely sensitive electrical circuits, it may be desirable to employ distilled or deionized water and a fairly high grade oP citric acid.
Alternatively, a non-toxic medium which ties up free 25water may be used for lower concentrations of citric acld.
An ethoxylated linear alcohol may be used for this purpose.
The flux may contain other components, such as impuri-ties, whether accidental or deliberate, so long as such ad-ditives have no adverse effect on the soldering results.
30The ratio of emulsifier to citric acid solution is preferably about 1:1; the emulsifier is used to suspend the oil in the citric acid.
An especially preferred flux composition for cored solder consists essentially of the following:
35(1) about 1 to 5 wt% botanical oil;
(2) about 47.5 to 49.5 wt% emulsifier, and ' ` , ' '':: , ~: .
-2~375~
~3) about 47.5 to 49.5 wt% citric acid solution (3% to saturated).
Any of the common soldering alloys may be employed, including 60/40 Sn/Pb, 62/2/36 Sn/Ag/Pb, 63/37 Sn/Pb, and 96~4 Sn/Ag. Typically, 60/40 and 63/37 solders are used.
As is well-known, a hollow cylinder of the solder is co-extruded with the flux to form the composit~ cored solder.
Tha flux/cored solder is most advantageously employed in surface mount component soldering processes. The flux contains no volatile organic compounds (VOCs) or other evaporative solvents, such as iso-propyl alcohol. The wa-tar-soluble solder flux of the invention avoids tha use oE
rosin-cored solders, which necessitate the use of chloro-fluorocarbon-type defluxing agents; rather, the flux of the invention is ~asily defluxed using deionized water.
The flux of the invention provides the following ad-vantages:
1. It eliminates harmful environmental emissions normally associated with rosin-cored fluxes, flux thinner (such as iso-propyl alcohol), and associated defluxing ag~nts (such as 1,1,1-trichloroethane). Indeed, cleaning of the flux is simply done in warm or hot water. Thus, the new flux is environmentally safe.
2. It provides soldering personnel with a non toxic, extremely safe, and highly effective flux/cored sol-der to use.
3. Its use cuts the actual soldering time by ap-proximately 70%. rrhis enables soldering to proceed at a considerably higher rate than permitted by rosin-cored sol-ders, thereby subjecting electronic components to the heat of the solder for a far shorter period of time.
4. Its use provides solder joints that evidence a more lustrous connection with excellent wetting and an estimated 80~ reduction in solder defects, compared with rosin-cored solders.
;
20~3~
INDUSTRIAL APPLICABILIrrY
The flux/cored solder of the invention is expected to find use in commercial soldering operations, particularly in soldering electrical components in circuit boards.
Thus, there has been disclosed a non-toxic, non-cor-rosive, environmentally-safe, water-soluble flux for cored solders, suitable for use in soldering electrical compo-nents. It will be clear to those skilled in the art thatvarious changes and modifications of an obvious nature may be made, and all such changes and modifications are consid-ered to fall within the scope of the invention, as defined by the appended claims.
.. ,~
., ,~
;
20~3~
INDUSTRIAL APPLICABILIrrY
The flux/cored solder of the invention is expected to find use in commercial soldering operations, particularly in soldering electrical components in circuit boards.
Thus, there has been disclosed a non-toxic, non-cor-rosive, environmentally-safe, water-soluble flux for cored solders, suitable for use in soldering electrical compo-nents. It will be clear to those skilled in the art thatvarious changes and modifications of an obvious nature may be made, and all such changes and modifications are consid-ered to fall within the scope of the invention, as defined by the appended claims.
.. ,~
., ,~
Claims (10)
1. A water-soluble flux for cored solders comprising:
(a) at least one botanical oil;
(b) at least one emulsifier; and (c) an aqueous solution of at least one water-soluble organic acid having at least two carboxylic acid groups.
(a) at least one botanical oil;
(b) at least one emulsifier; and (c) an aqueous solution of at least one water-soluble organic acid having at least two carboxylic acid groups.
2. The flux composition of Claim 1 wherein said solder consists essentially of a tin-based solder.
3. The flux composition of Claim 1 wherein said botan-ical oil comprises an oil selected from the group consist-ing of jojoba oil, palm oil, and peanut oil.
4. The flux composition of Claim 1 wherein said emul-sifier includes at least one surfactant.
5. The flux composition of Claim 4 wherein said sur-factant is selected from the group consisting of cationic, anionic, and non-ionic surfactants.
6. The flux composition of Claim 5 wherein said emul-sifier and said surfactant are selected from the group con-sisting of ethylene oxide and propylene oxide and adducts thereto, adducts of glycerol esters, polyoxyethylene sorbi-tan monopalmitate, polyoxyethylene sorbitan monolaurate, alkyl aryl polyether alcohol, polyoxyethylene sorbitan monooleate, polyoxyethylene sorbitan monostearate, and eth-oxylated linear alcohols.
7. The flux composition of Claim 1 wherein said organ-ic acid is selected from the group consisting of citric acid, malic acid, tartaric acid, glutamic acid, phthalic acid, and succinic acid.
8. The flux composition of Claim 7 wherein said organ-ic acid consists essentially of citric acid.
9. The flux composition of Claim 8 wherein said citric acid ranges from about 3 wt% to saturation of the flux com-position.
10. The flux composition of Claim 1 consisting essen-tially of:
(a) about 1 to 5 wt% botanical oil selected from the group consisting of jojoba oil, palm oil, and peanut oil;
(b) about 47.5 to 49.5 wt% emulsifier; and (c) about 47.5 to 49.5 wt% citric acid solution, said citric acid concentration ranging from about 3 wt% to saturation of said flux composition.
(a) about 1 to 5 wt% botanical oil selected from the group consisting of jojoba oil, palm oil, and peanut oil;
(b) about 47.5 to 49.5 wt% emulsifier; and (c) about 47.5 to 49.5 wt% citric acid solution, said citric acid concentration ranging from about 3 wt% to saturation of said flux composition.
Applications Claiming Priority (4)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US60720090A | 1990-10-31 | 1990-10-31 | |
| US60719990A | 1990-10-31 | 1990-10-31 | |
| US607,200 | 1990-10-31 | ||
| US607,199 | 1990-10-31 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA2053759A1 true CA2053759A1 (en) | 1992-05-01 |
Family
ID=27085451
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA002053759A Abandoned CA2053759A1 (en) | 1990-10-31 | 1991-10-18 | Water-soluble flux for cored solder |
Country Status (2)
| Country | Link |
|---|---|
| JP (1) | JPH0741433B2 (en) |
| CA (1) | CA2053759A1 (en) |
Families Citing this family (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5312027A (en) * | 1993-02-16 | 1994-05-17 | Hughes Aircraft Company | Precleaning of soldered circuit cards to prevent white residue |
| JP3750359B2 (en) * | 1998-07-24 | 2006-03-01 | 千住金属工業株式会社 | Water soluble flux for soldering |
| BRPI0017633B1 (en) * | 1999-12-03 | 2016-10-04 | Fry S Metals Inc D B A Alpha Metals Inc | Process for treating printed circuit board as well as printed circuit board |
-
1991
- 1991-10-18 CA CA002053759A patent/CA2053759A1/en not_active Abandoned
- 1991-10-31 JP JP28678291A patent/JPH0741433B2/en not_active Expired - Lifetime
Also Published As
| Publication number | Publication date |
|---|---|
| JPH04274896A (en) | 1992-09-30 |
| JPH0741433B2 (en) | 1995-05-10 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| EEER | Examination request | ||
| FZDE | Dead |