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WO1997049790A1 - Composition aqueuse de nettoyage pour l'elimination du flux et son mode d'utilisation - Google Patents

Composition aqueuse de nettoyage pour l'elimination du flux et son mode d'utilisation Download PDF

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Publication number
WO1997049790A1
WO1997049790A1 PCT/US1997/010109 US9710109W WO9749790A1 WO 1997049790 A1 WO1997049790 A1 WO 1997049790A1 US 9710109 W US9710109 W US 9710109W WO 9749790 A1 WO9749790 A1 WO 9749790A1
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WO
WIPO (PCT)
Prior art keywords
surfactant
salt
composition
alkali metal
flux
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.)
Ceased
Application number
PCT/US1997/010109
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English (en)
Inventor
Francis R. Cala
Richard A. Reynolds
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Church and Dwight Co Inc
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Church and Dwight Co Inc
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Filing date
Publication date
Application filed by Church and Dwight Co Inc filed Critical Church and Dwight Co Inc
Priority to AU34829/97A priority Critical patent/AU3482997A/en
Publication of WO1997049790A1 publication Critical patent/WO1997049790A1/fr
Anticipated expiration legal-status Critical
Ceased legal-status Critical Current

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Classifications

    • C—CHEMISTRY; METALLURGY
    • C11—ANIMAL OR VEGETABLE OILS, FATS, FATTY SUBSTANCES OR WAXES; FATTY ACIDS THEREFROM; DETERGENTS; CANDLES
    • C11D—DETERGENT COMPOSITIONS; USE OF SINGLE SUBSTANCES AS DETERGENTS; SOAP OR SOAP-MAKING; RESIN SOAPS; RECOVERY OF GLYCEROL
    • C11D3/00—Other compounding ingredients of detergent compositions covered in group C11D1/00
    • C11D3/16—Organic compounds
    • C11D3/26—Organic compounds containing nitrogen
    • C11D3/28—Heterocyclic compounds containing nitrogen in the ring
    • C—CHEMISTRY; METALLURGY
    • C11—ANIMAL OR VEGETABLE OILS, FATS, FATTY SUBSTANCES OR WAXES; FATTY ACIDS THEREFROM; DETERGENTS; CANDLES
    • C11D—DETERGENT COMPOSITIONS; USE OF SINGLE SUBSTANCES AS DETERGENTS; SOAP OR SOAP-MAKING; RESIN SOAPS; RECOVERY OF GLYCEROL
    • C11D1/00—Detergent compositions based essentially on surface-active compounds; Use of these compounds as a detergent
    • C11D1/004—Surface-active compounds containing F
    • C—CHEMISTRY; METALLURGY
    • C11—ANIMAL OR VEGETABLE OILS, FATS, FATTY SUBSTANCES OR WAXES; FATTY ACIDS THEREFROM; DETERGENTS; CANDLES
    • C11D—DETERGENT COMPOSITIONS; USE OF SINGLE SUBSTANCES AS DETERGENTS; SOAP OR SOAP-MAKING; RESIN SOAPS; RECOVERY OF GLYCEROL
    • C11D3/00—Other compounding ingredients of detergent compositions covered in group C11D1/00
    • C11D3/02—Inorganic compounds ; Elemental compounds
    • C11D3/04—Water-soluble compounds
    • C11D3/10—Carbonates ; Bicarbonates
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L21/00—Processes or apparatus adapted for the manufacture or treatment of semiconductor or solid state devices or of parts thereof
    • H01L21/02—Manufacture or treatment of semiconductor devices or of parts thereof
    • H01L21/04—Manufacture or treatment of semiconductor devices or of parts thereof the devices having potential barriers, e.g. a PN junction, depletion layer or carrier concentration layer
    • H01L21/48—Manufacture or treatment of parts, e.g. containers, prior to assembly of the devices, using processes not provided for in a single one of the groups H01L21/18 - H01L21/326 or H10D48/04 - H10D48/07
    • H01L21/4814—Conductive parts
    • H01L21/4821—Flat leads, e.g. lead frames with or without insulating supports
    • H01L21/4835—Cleaning, e.g. removing of solder
    • C—CHEMISTRY; METALLURGY
    • C11—ANIMAL OR VEGETABLE OILS, FATS, FATTY SUBSTANCES OR WAXES; FATTY ACIDS THEREFROM; DETERGENTS; CANDLES
    • C11D—DETERGENT COMPOSITIONS; USE OF SINGLE SUBSTANCES AS DETERGENTS; SOAP OR SOAP-MAKING; RESIN SOAPS; RECOVERY OF GLYCEROL
    • C11D2111/00—Cleaning compositions characterised by the objects to be cleaned; Cleaning compositions characterised by non-standard cleaning or washing processes
    • C11D2111/10—Objects to be cleaned
    • C11D2111/14—Hard surfaces
    • C11D2111/22—Electronic devices, e.g. PCBs or semiconductors
    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05K—PRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS
    • H05K3/00—Apparatus or processes for manufacturing printed circuits
    • H05K3/22—Secondary treatment of printed circuits
    • H05K3/26—Cleaning or polishing of the conductive pattern

Definitions

  • This invention relates to aqueous cleaning compositions and methods of using same to remove rosin flux residues from substrates. More particularly, this invention relates to aqueous cleaning compositions containing alkaline salts and a particular surfactant formulation which includes fluorinated surfactants, and methods of using such compositions to remove rosin flux residues from electronic circuit assemblies.
  • electrical components such as resistors, capacitors, inductors, transistors, integrated circuits, chip carriers and the like, are typically mounted on circuit boards in one of two ways.
  • the electronic components or modules are designed to mount to the printed circuit boards (PCBs) by means of plated through-holes in which the metal leads of the modules are spaced apart and sized to fit into corresponding plated through-holes and extend a small distance beyond the undersurface of the PCB.
  • PCBs printed circuit boards
  • An alternative to the through-hole technique for mounting electronic modules on PCBs is surface mount technology (SMT) wherein the leads of electronic modules are soldered to metal pads plated on the surface of a printed wiring board.
  • SMT surface mount technology
  • a solder paste is applied to the metal pads and subsequently the electronic components are precisely placed on the PCB such that the coplanar leads of the module contact corresponding pads on the circuit board which are coated with a layer of solder paste.
  • the solder paste comprises a soft solder alloy typically in a powder form and dispersed in a liquid medium conventionally containing a fluxing composition, an organic solvent and a thickening agent which provides the desired viscous or paste-like consistency to the solder formulation.
  • the solder paste typically has sufficient adhesive strength to hold the components in position until the solder is melted.
  • the entire PCB assembly is heated in a reflow oven to melt the solder in the solder paste thereby forming solder joints which permanently affix and electrically connect the electronic modules to the PCB. The assembly is then washed to remove the flux residue and tested.
  • Soldering fluxes fall into three broad categories: rosin fluxes, water-soluble fluxes, and no-clean fluxes. Rosin fluxes, which have a relatively long history of use and are still widely used in the electronics industry, are generally only moderately corrosive. Water-soluble fluxes, which are a more recent development and which are increasingly used in consumer electronics, are highly corrosive materials. No-clean fluxes, a very recent development, reportedly do not require removal from the circuit assemblies.
  • rosin fluxes have been removed from printed circuit boards by means of chlorinated hydrocarbon solvents, mixtures of such solvents or other volatile organic solvent materials.
  • the use of such solvents is disadvantageous in view of the toxicity and environmental problems inherent in such materials and, accordingly, the use of such solvents is in the process of being banned by international treaty or has been subjected to close scrutiny by various government agencies.
  • the present assignee has developed the ARMAKLEEN® cleaner which is an aqueous-based cleaner comprising alkali metal salts such as alkali metal carbonate and/or alkali metal bicarbonate salts, alkali metal silicates for use as a corrosion inhibitor as well as organic adjuvants such as surfactants to improve the efficacy of cleaning, anionic polymers to stabilize the silicate in solution as well as hydrotropes to maintain the surfactants in aqueous solution.
  • ARMAKLEEN® cleaners are described, for example, in U.S. Patent Nos. 5,234,505 and 5,234,506, which are hereby incorporated by reference herein. These aqueous-based cleaners have been found to be very effective for removing rosin flux residues and are substantially safer to use relative to the operator and the environment than the previous organic solvent-based cleaners.
  • aqueous-based cleaners are very effective in removing soldering rosin flux residues from the substrate of an electronic circuit assembly, it is continually desirable to provide improved compositions and methods for removing rosin flux residues from electronic circuit assemblies.
  • the high SMT component densities make it even more difficult to ensure complete removal of flux residues.
  • the ARMAKLEEN® cleaners disclosed for example in U.S. Patent No. 5,431,847 (which is hereby incorporated by reference herein) and in copending, commonly assigned U.S. Application Serial No. 08/417,883, filed April 6, 1995 include nonionic alkoxylate and N-alkylpyrrolidone surfactants either alone, or preferably, in mixtures to enhance cleaning efficacy. While the ARMAKLEEN® aqueous- based cleaners have been shown to be very effective rosin flux removers, it is still desirable to provide such aqueous cleaners with a surfactant formulation which can reduce the surface tension thereof and enhance the flux- removing ability of the cleaner especially in view of the ever increasing component density on the boards.
  • the boards are plated, etched, handled by operators in assembly, coated with corrosive or potentially corrosive fluxes, and soldered. Thus, contamination other than from fluxes are present.
  • the cleanliness of the electronic circuit assemblies, such as printed circuit boards or printed wiring boards, is generally regarded as being critical to their functional reliability. Accordingly, all ionic and nonionic contamination on a circuit assembly can lead to premature failure of the assembly by allowing short circuits to develop therein.
  • Fluoro-containing surfactants are known. However, the use of same in purely aqueous cleaners (no organic solvents) and the use of such cleaners to remove rosin flux is not believed to be known.
  • a no-clean soldering flux containing a halide-free, water-soluble activator and a fluorinated surfactant in water is disclosed, e.g. , in U.S. Patent No. 5,297,721 (Schneider et al.) .
  • a primary object of this invention is to provide an improved aqueous alkaline salt-based cleaning composition for removing rosin flux residues from a substrate, preferably a substrate of an electronic circuit assembly, wherein the cleaning composition has a reduced surface tension and, thus, improved flux-removing capacity.
  • a further object of the present invention is to provide a method of removing rosin flux residues from a substrate, preferably a substrate of an electronic circuit assembly, by means of a cleaning composition which has a reduced surface tension and, thus, improved flux-removing capacity.
  • the present invention is based on the discovery that, in an alkaline-salt-based aqueous cleaning composition, the use of a certain surfactant formulation which includes one or more fluorinated, nonionic surfactants provides the composition with a reduced surface tension and, consequently, an improved flux- removing capacity. Accordingly, one aspect of the present invention is directed to an aqueous cleaning composition containing:
  • a further aspect of the present invention is directed to an aqueous cleaning composition containing:
  • A a solvent phase consisting essentially of water; and (B) a flux-removing phase containing an alkaline salt component and a surfactant formulation, the alkaline salt component containing at least one alkali metal salt, and the surfactant formulation containing at least one fluorinated surfactant and at least one N- alkylpyrrolidone surfactant.
  • Another aspect of the present invention is directed to a method of removing soldering rosin flux residues from a substrate, involving the steps of:
  • the cleaning composition of this invention is preferably formulated as an aqueous concentrate.
  • the concentrate is preferably diluted with additional water and applied as a cleaning solution onto the substrate to be cleaned.
  • the aqueous concentrate and diluted solution are each buffered so as to have a pH of at least about 10.
  • the alkaline salt component contains one or more alkali metal carbonates or bicarbonates or mixtures thereof.
  • the flux-removing phase of the cleaning composition of this invention preferably further includes a corrosion inhibitor, most preferably, an alkali metal silicate such as potassium silicate.
  • the improved cleaning composition of this invention is non-toxic, non-corrosive, and has improved ability to substantially remove rosin flux residues from substrates containing such residues.
  • the solvent phase of the composition of this invention consists essentially of water.
  • the flux- removing phase of the composition contains an alkaline salt component and a surfactant formulation, wherein the alkaline salt component is made up at least one alkali metal salt, while the surfactant formulation contains at least one fluorinated, nonionic surfactant.
  • alkali metal salts for use in this invention are the salts of potassium, sodium and ammonium, with potassium salts being most preferred.
  • Especially preferred salts are the carbonates and bicarbonates and hydrates thereof, which are economical, safe and environmentally friendly.
  • Preferred carbonate salts include, e.g., potassium carbonate, potassium carbonate dihydrate, potassium carbonate trihydrate, sodium carbonate, sodium carbonate decahydrate, sodium carbonate heptahydrate, sodium carbonate monohydrate, sodium sesquicarbonate and the double salts and mixtures thereof.
  • Preferred bicarbonate salts include potassium bicarbonate and sodium bicarbonate and mixtures thereof.
  • suitable alkaline salts for use in the present invention include, e.g., the alkali metal ortho or complex phosphates.
  • the complex phosphates are especially effective because of their ability to chelate water hardness and heavy metal ions.
  • the complex phosphates include, e.g., sodium or potassium pyrophosphate, tripolyphosphate, and hexametaphosphates.
  • Other suitable alkaline salts include, e.g. , the alkali metal borates, acetates, citrates, tartrates, gluconates, succinates, silicates, phosphonates, nitrilotriacetates, edates, and the like.
  • the alkaline salt component used in the composition of this invention comprises a mixture of potassium and/or sodium carbonate and/or bicarbonate salts.
  • the flux-removing phase of the composition of this invention will contain the alkaline salt component in an amount which is sufficient to provide the aqueous composition or the concentrate or solution forms thereof with a pH of at least about 10, more preferably from about from about 10 to about 13, most preferably from about 11 to about 13.
  • the desired pH of the composition may depend on the type of flux being removed. Thus, the lower pH range is desirable and effective for removing the more easily removed fluxes. However, a pH of above 11.5 is preferred when removing the more difficult to remove solder paste fluxes.
  • the alkaline salt component has an adequate reserve of titratable alkalinity, at least equivalent to from about 0.2% to 4.5%, preferably from about 0.6% to 4.5% caustic potash (potassium hydroxide), when titrated to the colorless phenolphthalein end point, which is about a pH of 8.4 to maintain enhanced performance.
  • the alkaline salt component will be present in an amount ranging from about 45% to about 60% by weight of the flux-removing phase.
  • the composition of this invention further contains a surfactant formulation which includes at least one non ⁇ ionic fluorinated surfactant.
  • the surfactant formulation may be composed of the fluorinated surfactant(s) alone or, preferably, in combination with other non-fluorinated surfactants.
  • the fluorinated surfactant for use in the present invention is a fluorinated hydrocarbon.
  • the most preferred fluorinated surfactants for use in the present invention are Zonyl FSO Fluorosurfactant (described as a perfluoroalkyl ethoxylate) available from E. I. DuPont de Nemours & Co., Inc., and Fluorad FC-430 surfactant (described as a fluoroaliphatic polymeric ester) available from the Industrial Chemical Products Division of 3M.
  • Suitable non-fluorinated surfactants which can be used in the present invention include anionic, nonionic, cationic surfactants or amphoteric surfactants or combinations thereof.
  • the non-fluorinated surfactants should be soluble, stable and preferably, non-foaming in use. A combination of non-fluorinated surfactants may be used.
  • the term "non-fluorinated surfactant" as used herein may include other forms of dispersing agents or aids.
  • Nonionic alkoxylated alcohols which are sold under the tradename of "Polytergent SL-Series” surfactants by Olin Corporation.
  • An effective non-fluorinated surfactant which also provides antifoam properties is "Polytergent
  • non-fluorinated, nonionic surfactants include the block copolymers of ethylene oxide and propylene oxide such as those provided by BASF Corporation as Pluronics.
  • Ethoxylated alcohols with 8 to 20 carbons, such as those containing from 3 to 30 moles of ethylene oxide per mole of alcohol may also be used as non-fluorinated surfactants in this invention.
  • composition of this invention further contains a surfactant formulation which includes at least one fluorinated, nonionic surfactant and at least one N- alkylpyrrolidone surfactant.
  • N-alkylpyrrolidone surfactants which can be used in the composition of this invention are N-(n- alkyl)-2-pyrrolidones wherein the alkyl group contains from about 6 to about 15 carbon atoms. These compounds are described, e.g., in U.S. Patent No. 5,093,031, which is hereby incorporated by reference herein in its entirety.
  • the most preferred N-alkylpyrrolidone surfactant for use in this invention is N- octylpyrrolidone.
  • N-alkylpyrrolidones having a molecular weight of from about 180 to about 450 are conveniently prepared by several known processes, including the reaction between a lactone having the formula:
  • n is an integer from 1 to 3, and an amine having the formula R'-NH 2 , wherein R' is a linear alkyl group having from 6 to 20 carbon atoms.
  • the amine reactant having the formula R'-NH-. includes alkylamines having from 6 to 20 carbon atoms; amines derived from natural products, such as coconut amines or tallow amines distilled cuts or hydrogenated derivatives of such fatty amines. Also, mixtures of amine reactants can be used in the process for preparing the pyrrolidone compounds.
  • Such mixtures can include linear amino species having an alkyl of the same or different molecular weight.
  • the amine and lactone reactants combined in a mole ratio of from about 1:1 to about 1:5, are reacted under conditions of constant agitation, at a temperature between 100°C and about 350°C. under a pressure of from atmospheric to about 650 psig for a period of from about 1 to about 15 hours; preferably at 250°C to 300°C under an initial ambient pressure for a period of from 5 to 10 hours.
  • the resulting pyrrolidone product is recovered and purified by distillation or by any other convenient recovery process.
  • the N-alkylpyrrolidone products having 11 to 14 carbon atoms are clear, water white liquids, at room temperature; whereas those having 16 or more carbon atoms are solids. These pyrrolidones have a neutral or slightly basic pH, a surface tension of between about 25 and about 35 dynes/cm as a 0.1% water solution and a viscosity of from about 6 to about 30 cps at 25°C.
  • the C 6 to C H alkyl pyrrolidones display primarily surfactant properties; whereas the C 16 to C-, 2 alkyl species are primarily complexing agents; although some degree of surfactant and complexing capability exists in all of the present species.
  • the amount of the surfactant formulation (including fluorinated surfactant, non-fluorinated surfactant, and any antifoam agents) used in the composition of this invention will preferably be no more than about 20%, preferably from about 2% to about 20%, by weight of the composition but can be varied depending on the conditions and contamination encountered.
  • the composition will contain from about 0.01% to about 5%, more preferably from about 0.01% to about 1.0%, and most preferably from about 0.05% to about 0.5%, by weight of the fluorinated surfactant.
  • composition will contain the N- alkylpyrrolidone surfactant in an amount ranging from about 0.1% to about 5.0%, more preferably from about 0.5% to about 2.0%, and most preferably from about 1.0% to about 1.5% by weight.
  • the cleaning composition used in the present invention preferably further contains at least one antifoam agent.
  • the antifoam agent prevents the formation of excessive foam caused by the combination of rosin flux and the aqueous composition of this invention. The presence of foam interferes with the mechanical action of the cleaning equipment used to wash the circuit boards. It is important, if not critical, that the antifoam agent(s) used herein does not act by replacing the flux film with another residual surface film which could affect the performance of the electronic circuit assembly in use.
  • the antifoam agent could be an agent which solely acts to inhibit foam or it could be a surfactant which helps clean the boards and emulsify soils such as the nonionic Polytergent SLF-18 or Surfonic LF37 described hereinabove.
  • the antifoam agent(s) which can be used in the present invention may be an agent which solely acts to inhibit foam or may be a surfactant which helps clean the electronic circuit assembly substrate and emulsify soils.
  • preferred antifoam agents which can be used in the present invention include those disclosed in U.S. Patent No. 5,234,505, which has been previously incorporated by reference herein. Such compounds include those formed by condensing ethylene oxide with a hydrophobic base formed by the condensation of propylene oxide with propylene glycol.
  • suitable antifoam agents include the "Pluronics" agents sold by BASF - Wyandotte. These compounds also enhance flux removal.
  • antifoam agents that also enhance flux removal include: the polyethylene oxide/polypropylene oxide condensates of alkyl phenols having an alkyl group containing from about 6 to about 12 carbon atoms in either a straight chain or branched chain configuration, with ethylene oxide/propylene oxide, the ethylene oxide being present in amounts equal to 1 to 25 moles of ethylene oxide per mole of alkyl phenol and the propylene oxide being present in amounts equal to 1 to 25 moles of propylene oxide per mole of alkyl phenol.
  • the alkyl substituent in such compounds may be derived from, e.g., polymerized propylene, diisobutylene, octene or nonene.
  • antifoam agents include those derived from the condensation of ethylene oxide with the product resulting from the reaction of propylene oxide and ethylene-diamine or from the product of the reaction of a fatty acid with sugar, starch or cellulose.
  • the antifoam agent may be the condensation product of aliphatic alcohols having from 8 to 18 carbon atoms, in either straight chain or branched chain configuration, with ethylene oxide and propylene oxide.
  • the antifoam agent(s) is preferably present in an amount ranging from about 0.01% to 0.5% by weight of the concentrate.
  • hydrotrope in the aqueous cleaning composition of this invention to help solubilize any organic adjuvants such as surfactants, anti-foam agents, and the like, which are present in the salt-containing compositions.
  • the hydrotrope will be present in the aqueous concentrate formulation of the aqueous composition of this invention in an amount which does not exceed about 3% by weight, and preferably ranges from about 0.2% to about 3% by weight of the concentrate.
  • Hydrotropes suitable for use in this invention include those disclosed in U.S. Patent No. 5,234,505, which has previously been incorporated by reference herein.
  • preferred hydrotropes which can be used in the present invention include the sodium, potassium, ammonium and alkanol ammonium salts of xylene, toluene, ethylbenzoate, isopropylbenzene, naphthalene, alkyl naphthalene sulfonates, phosphate esters of alkoxylated alkyl phenols, phosphate esters of alkoxylated alcohols and sodium, potassium and ammonium salts of the alkyl sarcosinates.
  • the hydrotropes are useful in maintaining the organic materials including the surfactant readily dispersed in the aqueous cleaning solution and, in particular, in an aqueous concentrate which is an especially preferred form of packaging the compositions of the invention and allow the user of the compositions to accurately provide the desired amount of cleaning composition into the aqueous wash solution.
  • a particularly preferred hydrotrope is one that does not foam.
  • the most useful of such hydrotropes are those which comprise the alkali metal salts of intermediate chain length linear monocarboxylic fatty acids, i.e., C 7 -C 13 .
  • Particularly preferred are the alkali metal octanoates and nonanoates.
  • the hydrotrope(s) is preferably present in the composition of this invention in an amount ranging from about 1% to about 20% by weight, more preferably, from about 5% to about 15% by weight.
  • the cleaning composition of this invention preferably includes a corrosion inhibitor, preferably an alkali metal silicate, which is added to provide improved anti-corrosion protection to the electronic circuit assembly as well as to ensure bright metallic surfaces including the solder joints as well as any connecting tabs and the like.
  • a corrosion inhibitor preferably an alkali metal silicate
  • any of the lithium, sodium or potassium silicates are useful in the cleaning compositions of this invention.
  • the sodium or potassium silicates are used and, most preferably, potassium silicate is used.
  • the alkali metal silicates which are used can be in a variety of forms which can be encompassed generally by the formula M 2 0:Si0 2 wherein M represents the alkali metal and in which the ratio of the two oxides can vary.
  • alkali metal silicates will have an M 2 0 to Si0 2 mole ratio of between 1:1.5 and 1:4.5. Most preferably, the M 2 0:Si0 2 ratio is between 1:1.6 and 1:4.0. Such silicates also provide additional alkalinity to the wash water to help cleaning.
  • the corrosion inhibitor will be present in the cleaning composition of this invention in amounts ranging from about 0.1% to 10% by weight, based on the flux- removing phase.
  • the corrosion inhibitor preferably, the alkali metal silicate, and, most preferably, potassium silicate, can be added to the flux-removing phase and added to the wash bath or, preferably, is added with the flux-removing phase in aqueous solution to form the aqueous concentrate.
  • a drawback to the use of alkali metal silicates in aqueous solutions having relatively low pH levels is that silicate tends to precipitate from the aqueous solution.
  • the silicate may be stabilized and maintained in solution by adding an anionic polymer to the solution.
  • Suitable anionic polymers are disclosed, e.g., in U.S. Patent Nos. 5,234,505 and 5,431,847, which have previously been incorporated by reference herein.
  • Particularly preferred anionic polymers are those containing carboxylate groups.
  • anionic homopolymers or copolymers with molecular weights of between about 1000 to about 5,000,000 or mixtures thereof are usefully employed in this invention as silicate stabilizers.
  • the optimal polymers are ones which dissolve easily and do not increase the viscosity of the solutions to excessive levels when added at the concentration required for optimum silicate stability.
  • anionic polymers are non-inclusive examples of those suitable for stabilizing silicate solutions: carboxymethylcellulose, polyacrylic acid, polymethacrylic acid, polymaleic acid, polyglycolic acid, heteropolymers of acrylic and methacrylic acid, xanthan gum, carrageenan gum, and alginate gum.
  • the anionic polymers are essentially present in the form of the sodium or potassium salt thereof. Additional alkali can be added to neutralize the polymers.
  • a preferred silicate stabilizing agent is a high molecular weight polyacrylic acid such as in the form of sodium polyacrylate in solution.
  • This polyacrylate should have a molecular weight of between about 100,000 to about 4,000,000, preferably from over 150,000 to 4,000,000.
  • An especially preferred molecular weight range is about 250,000 to about 2,000,000. Examples of such polymers are marketed under the tradename "Carbopol", from B.F. Goodrich.
  • the polyacrylic acid stabilizers have been found to be very effective in maintaining the alkali metal silicate in solution, in particular, when the composition is in the form of an aqueous concentrate as hereinbefore defined. Accordingly, relatively small amounts of the anionic polymer are effective. Thus, at silicate concentrations of from about 0.5% to about 10.0% by weight in the cleaning concentrate, amounts of the polyacrylic acid needed for stabilization range from about 0.1% to about 2% by weight.
  • the aqueous cleaning composition of this invention is generally formulated either in the form of a concentrate or a dilute solution.
  • the cleaning composition of the present invention is prepared as an aqueous concentrate.
  • the concentrate preferably contains from about 5% to about 45% by weight of the flux-removing phase and from about 55% to about 95% by weight of the solvent phase. More preferably, the concentrate contains from about 10% to about 30% by weight of the flux-removing phase and from about 70% to about 90% by weight of the solvent phase. Most preferably, the concentrate contains from about 15% to about 20% by weight of the flux-removing phase and from about 80% to about 85% by weight of the solvent phase.
  • the cleaning composition of this invention will preferably contain from about 0.5% to about 10% by weight, more preferably from about 0.9% to about 5% by weight, and most preferably from about 1% to about 3% by weight, of the flux-removing phase; and from about 90% to about 99.5% by weight, more preferably from about 95% to about 99.1% by weight, and most preferably from about 97% to about 99% by weight, of the solvent phase.
  • the specific amount of water added to the concentrate to form the dilute solution formulation of the composition of this invention will vary according to factors relating to manufacturing, packaging, shipping, and storage.
  • additives, adjuvants and the like may be included with the flux-removing phase, the aqueous concentrate formulation or the aqueous solution formulation of the composition of this invention.
  • the cleaning process for removing flux residues is a continuous process.
  • the circuit assemblies are deposited on a conveyor assembly which traverses one or more cleaning stations and one or more rinsing stations.
  • Each cleaning and rinsing station is a tank or other similar receptacle wherein the conveyor assembly containing the assemblies is immersed and then withdrawn to drain excess solution from the assemblies.
  • the cleaning solution or rinse water can be applied by spray nozzles within the respective wash or rinse tanks.
  • the conveyor assembly is then withdrawn from the tank and the circuit assemblies removed from the conveyor system which is then recycled to carry more circuit assemblies through the cleaning process.
  • the aqueous cleaning composition of this invention may be applied to the boards by immersion in dip tanks or by hand or mechanical brushing.
  • the aqueous concentrate or solution may be applied by any of the commercially available printed wiring board cleaning equipment.
  • Dishwasher size units may be used, or much larger cleaning systems such as the "Poly-Clean +" and the various "Hydro-Station" models produced by Hollis Automation, Inc. of Nashua, N.H.
  • these washers may apply the concentrate or solution by spraying with mechanical nozzles or by rolling contact with wetted roller surfaces.
  • the temperature at which the concentrate or solution may be applied can range from ambient temperature (about 70°F) to about 180°F, preferably, about 140°F. to 170°F.
  • solder flux has been loosened and removed during a period of contact which typically ranges from about 1 to about 5 minutes, but may be longer up to about 10 minutes
  • the boards are taken from the concentrate or solution.
  • Another advantage of the instant invention is that the aqueous cleaning composition need not be flushed with solvents as with the processes of the prior art.
  • the boards may simply be flushed with water for a period of up to about 2 minutes. Deionized water is preferred.
  • the optimal rinsing time varies according to the kinds of surfactants and the concentrations of the aqueous cleaning compositions used and can easily be determined by routine experimentation.
  • the cleaned boards are then dried, preferably with forced air. Drying is expedited if the air is warmed, preferably to above about 100°F.
  • the aqueous cleaning composition of this invention is also effective in removing other undesirable and deleterious substances and residues.
  • substances and residues include, for example, non-rosin flux, photoresist, solder masks, adhesives, machine oils, greases, silicones, lanolin, mold release, polyglycols, and plasticizers.

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Abstract

L'invention porte sur une composition aqueuse de nettoyage pour l'élimination du flux contenant: (A) une phase solvant essentiellement composée d'eau, et (B) une phase d'élimination du flux contenant un composant à sel(s) alcalin(s) et une formulation de tensio-actif, le composant à sel(s) alcalin(s) comportant au moins un sel de métal alcalin et la formulation de tensio-actif contenant au moins un tensio-actif non ionique fluoré. Le procédé d'élimination du flux de résine d'un substrat, de préférence d'un circuit électronique, consiste: (a) à nettoyer le substrat à l'aide de la composition aqueuse ci-dessus pendant un temps suffisant pour émulsionner les résidus de résine de soudure et former des résidus de flux de résine émulsionnés, puis (b) à éliminer lesdits résidus du substrat.
PCT/US1997/010109 1996-06-26 1997-06-23 Composition aqueuse de nettoyage pour l'elimination du flux et son mode d'utilisation Ceased WO1997049790A1 (fr)

Priority Applications (1)

Application Number Priority Date Filing Date Title
AU34829/97A AU3482997A (en) 1996-06-26 1997-06-23 Aqueous cleaning composition for removing flux and method of use

Applications Claiming Priority (4)

Application Number Priority Date Filing Date Title
US2057696P 1996-06-26 1996-06-26
US2057596P 1996-06-26 1996-06-26
US60/020,576 1996-06-26
US60/020,575 1996-06-26

Publications (1)

Publication Number Publication Date
WO1997049790A1 true WO1997049790A1 (fr) 1997-12-31

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PCT/US1997/010109 Ceased WO1997049790A1 (fr) 1996-06-26 1997-06-23 Composition aqueuse de nettoyage pour l'elimination du flux et son mode d'utilisation

Country Status (2)

Country Link
AU (1) AU3482997A (fr)
WO (1) WO1997049790A1 (fr)

Citations (13)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4381951A (en) * 1978-01-25 1983-05-03 Western Electric Co. Inc. Method of removing contaminants from a surface
JPH03212497A (ja) * 1990-01-18 1991-09-18 Nippon Alpha Metals Kk 洗浄組成物
WO1992022678A1 (fr) * 1991-06-14 1992-12-23 Petroferm Inc. Composition et procede d'elimination du flux a souder a la resine a l'aide de terpene et d'hydrocarbures
US5234506A (en) * 1991-07-17 1993-08-10 Church & Dwight Co., Inc. Aqueous electronic circuit assembly cleaner and method
US5234505A (en) * 1991-07-17 1993-08-10 Church & Dwight Co., Inc. Stabilization of silicate solutions
US5261967A (en) * 1991-07-17 1993-11-16 Church & Dwight Co, Inc. Powdered electric circuit assembly cleaner
US5264046A (en) * 1991-07-17 1993-11-23 Church & Dwight Co., Inc. Aqueous electronic circuit assembly cleaner and cleaning method
US5264047A (en) * 1991-07-17 1993-11-23 Church & Dwight Co., Inc. Low foaming effective hydrotrope
US5399284A (en) * 1991-04-03 1995-03-21 Chemische Fabrik Dr. Weigert (Gmbh & Co.) Process for removing starch-containing contamination from dishes and surfactant concentrates suitable for this process
US5431847A (en) * 1991-07-17 1995-07-11 Charles B. Barris Aqueous cleaning concentrates
US5433885A (en) * 1991-07-17 1995-07-18 Church & Dwight Co., Inc. Stabilization of silicate solutions
US5466389A (en) * 1994-04-20 1995-11-14 J. T. Baker Inc. PH adjusted nonionic surfactant-containing alkaline cleaner composition for cleaning microelectronics substrates
US5498293A (en) * 1994-06-23 1996-03-12 Mallinckrodt Baker, Inc. Cleaning wafer substrates of metal contamination while maintaining wafer smoothness

Patent Citations (13)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4381951A (en) * 1978-01-25 1983-05-03 Western Electric Co. Inc. Method of removing contaminants from a surface
JPH03212497A (ja) * 1990-01-18 1991-09-18 Nippon Alpha Metals Kk 洗浄組成物
US5399284A (en) * 1991-04-03 1995-03-21 Chemische Fabrik Dr. Weigert (Gmbh & Co.) Process for removing starch-containing contamination from dishes and surfactant concentrates suitable for this process
WO1992022678A1 (fr) * 1991-06-14 1992-12-23 Petroferm Inc. Composition et procede d'elimination du flux a souder a la resine a l'aide de terpene et d'hydrocarbures
US5264046A (en) * 1991-07-17 1993-11-23 Church & Dwight Co., Inc. Aqueous electronic circuit assembly cleaner and cleaning method
US5261967A (en) * 1991-07-17 1993-11-16 Church & Dwight Co, Inc. Powdered electric circuit assembly cleaner
US5234505A (en) * 1991-07-17 1993-08-10 Church & Dwight Co., Inc. Stabilization of silicate solutions
US5264047A (en) * 1991-07-17 1993-11-23 Church & Dwight Co., Inc. Low foaming effective hydrotrope
US5234506A (en) * 1991-07-17 1993-08-10 Church & Dwight Co., Inc. Aqueous electronic circuit assembly cleaner and method
US5431847A (en) * 1991-07-17 1995-07-11 Charles B. Barris Aqueous cleaning concentrates
US5433885A (en) * 1991-07-17 1995-07-18 Church & Dwight Co., Inc. Stabilization of silicate solutions
US5466389A (en) * 1994-04-20 1995-11-14 J. T. Baker Inc. PH adjusted nonionic surfactant-containing alkaline cleaner composition for cleaning microelectronics substrates
US5498293A (en) * 1994-06-23 1996-03-12 Mallinckrodt Baker, Inc. Cleaning wafer substrates of metal contamination while maintaining wafer smoothness

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