Cleaning solvent compositions and their use

Abstract

A cleaning solvent composition comprises from about 0.2 to 15 weight percent of mono- or di-phosphate ester in free acid form, and from about 85 to 99.8 weight percent of one or more halogenated hydrocarbon solvents. Other cleaning solvent compositions further comprise one or more alcohols. For example, such alcohol-containing compositions may comprise from about 0.2 to 15 weight percent of mono- or di-phosphate ester in free acid form, from about 2 to about 25 weight percent of one or more alcohols, and from about 25 to about 97.8 weight percent of one or more halogenated hydrocarbon solvents.

Claims

1. A composition comprising from about 2 to about 4 weight percent of one or more free acid forms of ethoxylated alkyl-substituted phosphate ester surfactants selected from the group consisting of one or both of: ##STR00005## wherein R is selected from the group consisting of one or more of ethoxylated hydrocarbons, alkylated hydrocarbons, fluorinated hydrocarbons, and ethoxylated and fluorinated hydrocarbons; from about 2 to about 25 weight percent of an alcohol selected from the group consisting of one or more of straight chain and branched alkyl alcohols, monohydric and polyhydric aromatic alcohols and monohydric and polyhydric heteroaromatic alcohols; and from about 25 to about 97.8 weight percent of one or more halogenated hydrocarbon solvents, and wherein the halogenated hydrocarbon solvents comprise a blend of from about 66 to about 68 weight percent of trans-dichloroethylene, about 17 to about 19 weight percent of 2,3-dihydrodecafluoropentane, about 11 to about 13 weight percent of hepta-fluorocyclopentane and about 1 to about 4 weight percent of an alcohol selected from one or more of straight and branched chain alkyl alcohols, aromatic and heteroaromatic alcohols, all having from 1-20 carbon atoms and is present in the amount of from about 2 to about 15 weight percent of the composition, the blend being present in the amount of from about 96 to about 98 weight percent of the composition.

2. The composition of claim 1 wherein the alcohol comprises methanol.

3. The composition of claim 1 wherein R is one or more of ##STR00006## R is one or more of H, CH.sub.3, an alkyl group and an aryl group; and n is an integer from 2 to 20.

4. A composition comprising from about 2 to about 4 weight percent of one or more free acid forms of ethoxylated alkyl-substituted phosphate ester surfactants selected from the group consisting of one or both of: ##STR00007## wherein R is one or more of ##STR00008## wherein R is one or more of H, CH.sub.3, an alkyl group and an aryl group; and n is an integer from 2 to 20; from about 2 to about 25 weight percent of an alcohol selected from the group consisting of one or more of straight chain and branched alkyl alcohols, monohydric and polyhydric aromatic alcohols and monohydric and polyhydric heteroaromatic alcohols; and from about 25 to about 97.8 weight percent of one or more halogenated hydrocarbon solvents and wherein: the halogenated hydrocarbon solvent comprises a blend of about 40 to about 44 weight percent of trans-dichloroethylene, about 17 to about 19 weight percent of the hydrofluorocarbon pentafluorobutane, from about 36 to about 38 weight percent dihydrodecafluoropentane and from about 3 to about 4 weight percent methanol, the blend being present in the amount of from about 96 to about 98 weight percent of the composition.

5. The composition of claim 4 wherein the pentafluorobutane comprises 1,1,1,3,3-pentafluorobutane.

6. A composition comprising from about 1 to about 6 weight percent of one or more free acid forms of ethoxylated alkyl-substituted phosphate ester surfactants selected from the group consisting of: ##STR00009## wherein R is selected from the group consisting of one or more of ethoxylated hydrocarbons, alkylated hydrocarbons, fluorinated hydrocarbons, and ethoxylated and fluorinated hydrocarbons; and from about 85 to about 97.8 weight percent of a halogenated hydrocarbon solvent, wherein the halogenated hydrocarbon solvent is selected from the group consisting of one or more of perfluorocarbons (PFCs), chlorofluorocarbons (CFCs), hydrofluorocarbons (HFCs), hydrofluoroethers (HFEs), hydrofluoroolefins (HFOs), partially brominated hydrocarbons, fully brominated hydrocarbons, partially chlorinated hydrocarbons and fully chlorinated hydrocarbons and wherein: the halogenated hydrocarbon solvent comprises a blend of from about 80 to about 86 weight percent trans-dichloroethylene, from about 5 to about 9 weight percent 2,3-dihydrodecafluoropentane and from about 8 to about 12 weight percent hexafluorocyclopentane, the blend being present in the amount of from about 94 to about 99 weight percent of the composition.

7. The composition of claim 6 wherein R is one or more of ##STR00010## R is one or more of H, CH.sub.3, an alkyl group and an aryl group; and n is an integer from 2 to 20.

8. A composition comprising from about 2 to about 4 weight percent of one or more free acid forms of an ethoxylated alkyl-substituted phosphate ester surfactant selected from the group consisting of: ##STR00011## wherein R is selected from the group consisting of one or more of ethoxylated hydrocarbons, alkylated hydrocarbons, fluorinated hydrocarbons, and ethoxylated and fluorinated hydrocarbons; and from about 85 to about 97.8 weight percent of a halogenated hydrocarbon solvent comprising a blend of about 40 to about 44 weight percent of trans-dichloroethylene, about 17 to about 19 weight percent of the hydrofluorocarbon pentafluorobutane, from about 36 to about 38 weight percent dihydrodecafluoropentane and from about 3 to about 4 weight percent methanol, the blend being present in the amount of from about 96 to about 98 weight percent of the composition.

9. The composition of claim 8 wherein the pentafluorobutane comprises 1,1,1,3,3-pentafluorobutane.

Description

DETAILED DESCRIPTION OF THE INVENTION AND SPECIFIC EMBODIMENTS THEREOF

(1) The following abbreviations, trademarks and trade names have the following meanings, whether used in the singular or plural form.

(2) Solvent Formulations

(3) TDE. Trans-Dichloroethylene, Chemical Abstracts Number (CAS #) 156-60-5.

(4) HFCs. Hydrofluorocarbons such as HFC 43-10me, sold under the trademark Vertrel XF, CAS #1384-95-42 and HFC365mfc CAS #406-58-6. These materials are available from E.I. DuPont de Nemours and Co. of Wilmington, Del.

(5) HFEs. Hydrofluoroethers such as HFE 7100, CAS #163702-08-7 and 163702-07-6.

(6) NPB. n-Propyl bromide, CAS #106-94-5.

(7) Vertrel SFR. A blend of 67% trans-dichloroethylene, 18% 2,3-dihydrodecafluoropentane (HFC 43-10me); 12% heptafluorocyclopentane; 3% methanol. This material has a boiling point of 106 F. (41.1 C.) and is available from E.I. DuPont de Nemours and Co. of Wilmington, Del.
SION. A blend of 96% trans-dichloroethylene and 4% methylperfluorohexene (HFX-110). This material has a boiling point of 121 F. (49.4 C.) and is available from E.I. DuPont de Nemours and Co. of Wilmington, Del.
CMS. A blend of 41.5% trans-dichloroethylene, 18% HFC 365mfc, 37% 2,3-dihydrodecafluoropentane (HFC 43-10me), 3.5% methanol. This material has a boiling point of 97 F. (36.1 C.) and is available from MicroCare Corporation of New Britain, Conn., an affiliated company of the assignee of this application.
MCA. A blend of 62% trans-dichloroethylene, 38% 2,3-dihydrodecafluoropentane (HFC 43-10me). This material has a boiling point of 102 F. (38.9 C.) and is available from E.I. DuPont de Nemours and Co. of Wilmington, Del.
SDG. A blend of 83% trans-dichloroethylene, 7% 2,3-dihydrodecafluoropentane (HFC 43-10me); 10% hexafluorocyclopentane. Bp 109F. This material has a boiling point of 109 F. (42.8 C.) and is available from E.I. DuPont de Nemours and Co. of Wilmington, Del.
Vertrel XP. A blend of 96.75% 2,3-dihydrodecafluoropentane (HFC 43-10me), 3.25% isopropanol. This material has a boiling point of 126 F. (52.2 C.) and is available from E.I. DuPont de Nemours and Co. of Wilmington, Del.
CFCs. Chlorofluorocarbons such as those sold under the trademark Solstice, for example, trans-chlorotrifluoromethyl propene CAS #2730-43-0. This material has a boiling point of 68 F. (20 C.) and is available from Honeywell International of Morristown, N.J.
DBE. A blend of dimethyl succinate, glutarate and adipate having a boiling point of >250 F. (121.1 C.) is available from Invista of Wichita, Kans.

(8) Phosphate Esters

(9) Capstone FS-66. A fluorinated alkyl substituted phosphate ester in free acid form, available from E.I. DuPont de Nemours and Co. of Wilmington, Del.

(10) Rhodafac RS710. An ethoxylated alkyl substituted phosphate ester in free acid form, available from Solvay Rhodia which has a place of business in Houston, Tex.

(11) Soiling Substances

(12) No-Clean Lead-Free Solder Pastes available from Alpha Corporation of Altoona, Pa. and Suwanee, Ga. under the designation Omnix 340, or from Nihon Almit Co. Ltd. of Tokyo, Japan under the designation SN62U. Additional fluxes and pastes as are used in the industry are: AIM Corporation 217 Gel Flux, NC Paste Flux (257), NC Flux Pen (280), M8 Paste, RMA258-15R and Loctite Corporation GC3 (Water Soluble), Loctite GC10 and Alpha Corporation OM340 and Indium Corporation 8.9HF1 and SMQ92-J (Leaded).

(13) Standard Procedure.

(14) A stencil was made with 3-mm holes, a 3-mm pitch (edge-to-edge distance between holes) and a 0.075 mm thickness. Flux or solder paste were stencil printed onto 7.6215.24 mm (3 inch6 inch) steel panels creating a test array of 3-mm diameter by 0.075 mm high dots of paste. The paste dots were then reflowed by placing the steel plates in a 350 C. oven for 4 minutes or by passing through an Aminstrument T-962A benchtop reflow oven set to achieve 350 C. maximum for 2 minutes. Cleaning trials were conducted in standard 2-sump vapor degreasers or in bench top simulation using beakers of boiling cleaning solvent blend after which the cleaned dots were rinsed in an ambient rinse solution that did not contain phosphate esters. The following examples report the results of cleaning trials conducted pursuant to this Standard Procedure.

(15) In the following Examples 1-6, the types of components (Component Type) of each Cleaning Formulation tested is indicated by abbreviations in parentheses. The abbreviations are: HHC=halogenated hydrocarbon solvents; NHH=non-halogenated hydrocarbon solvents; ALC=alcohol; FAPE=free acid phosphate ester; and HFE=hydrofluoroether solvents. Unless otherwise stated, all references herein to the percentage of a component in a composition are percent by weight of the total weight of the composition.

Example 1. Chlorofluorocarbon Based Solvents Used to Clean No-Clean Solder Pastes as the Soiling Substance

(16) TABLE-US-00001 Cleaning Formulation Trial (Component Type) Cleaning Process Observation 1 100% Solstice 20 minutes boil Rosin binder of flux mostly (HHC) removed but significant white residue remains. 2 97% Solstice 20 minutes boil/ Rosin binder of flux mostly 3% Rhodafac RS710 1 minute rinse with removed but some white residue (HHC, FAPE) Solstice remains. 3 95% Solstice 20 minutes boil/ Rosin binder of flux mostly 5% DBE 1 minute rinse with removed but significant white (HHC, NHH) Solstice residue remains. 4 90% Solstice 20 minutes boil/ Rosin binder of flux mostly 5% DBE 1 minute rinse with removed but some white residue 5% Rhodafac RS710 Solstice remains. (HHC, NHH, FAPE) 5 97% Solstice 20 minutes boil/ Rosin binder of flux mostly 3% methanol 1 minute rinse with removed but some white residue (HHC, ALC) Solstice remains. 6 95% Solstice 20 minutes boil/ All flux residue removed 3% methanol 1 minute rinse with leaving clean solder balls 2% Rhodafac RS710 Solstice behind. (HHC, ALC, FAPE) 7 97% Solstice 20 minutes boil/ All flux residue removed 3% methanol 1 minute rinse with leaving clean solder balls 3% Capstone FS-66 Solstice behind. (HHC, ALC, FAPE)

(17) No-clean Solder Pastes contain organic binders or rosins in which are dispersed the solder and the surface activating components which help bond the solder to a substrate. The results of Example 1 show that especially in lead free, no clean systems, the binders can often be removed with existing cleaning formulations but the activators will be left behind leaving a characteristic white residue on the part. Addition of an alcohol to the cleaning composition (trial 5) is seen to help start removal of the ionic white residues but does not adequately clean the part. Trials 6 and 7 dramatically illustrate that the synergy of combining CFC, methanol and a phosphate ester acid successfully removes flux residue. Trials 3 and 4 show the importance of an alcohol component because substituting the strong organic solvent DBE for the methanol did not provide the desired results.

Example 2. HFC/TDE Blends Used to Clean Rosin Metal Activating (RMA) Solder Pastes as the Soiling Substance

(18) TABLE-US-00002 Cleaning Formulation Trial (Component Type) Cleaning Process Observation 8 100% Sion 10 minutes boil Paste mostly removed but a dull (HHC) finish left on the steel. 9 97% Sion 10 minutes boil/ Paste completely removed 3% Rhodafac RS710 1 minute rinse with and steel significantly (HHC, FAPE) Sion brightened. 10 100% SDG 10 minutes boil Paste mostly removed but a dull (HHC) finish left on the steel. 11 97% SDG 10 minutes boil/ Paste completely removed 3% Rhodafac RS710 1 minute rinse with and steel significantly (HHC, FAPE) SDG brightened. 12 100% Vertrel SFR 10 minutes boil Paste mostly removed but a dull (HHC, ALC) finish left on the steel. 13 97% Vertrel SFR 10 minutes boil/ Paste completely removed 3% Rhodafac RS710 1 minute rinse with and steel significantly (HHC, ALC, FAPE) SFR brightened. 14 100% CMS 10 minutes boil Paste mostly removed but a dull (HHC, ALC) finish left on the steel. 15 97% CMS 10 minutes boil/ Paste completely removed 3% Rhodafac RS710 1 minute rinse with and steel significantly (HHC, ALC, FAPE) CMS brightened.

(19) The results of Trials 9 and 11 of Example 2 show that excellent results were obtained without the use of alcohol as a co-solvent for the halogenated solvent component. Trials 13 and 15 show that addition of a phosphate ester acid to a cleaning composition containing alcohol and a halogenated hydrocarbon content will complete the cleaning process as well as achieve significant metal brightening.

Example 3. HFCs/TDE with Alcohol and Phosphate Ester Used to Clean No-Clean Solder Pastes as the Soiling Substance

(20) TABLE-US-00003 Cleaning Formulation Trial (Component Type) Cleaning Process Observation 16 100% SDG 10 minutes boil Paste mostly removed but significant (HHC) dull gray residue left behind. 17 100% Vertrel SFR 10 minutes boil Paste mostly removed but (HHC, ALC) some dull gray residue left behind. 18 97% Vertrel SFR 10 minutes boil/ Piece completely clean and metal 3% Rhodafac RS710 1 minute rinse with and solder brightened. (HHC, FAPE, ALC) SFR

(21) Trials 16 and 17 of Example 3 show that SDG and Vertrel SFR are close in cleaning capabilities. Both have high transdichloroethylene (TDE) content that removes organic soils readily. (SDG is 83% TDE and Vertrel SFR is 67% TDE. However, Trial 16 left behind significant dull gray ionic residues.) The addition of alcohol to the Vertrel SFR (Trial 17) somewhat improves the removal of ionic residues but still left some residue. However, the addition to Vertrel SFR of the free acid phosphate ester (Trial 18) enabled attainment of a fully cleaned and brightened part.

Example 4. HFEs/TDE with Alcohol and with Phosphate Ester Used to Clean No-Clean Solder Pastes as the Soiling Substance

(22) TABLE-US-00004 Cleaning Formulation Trial (Component Type) Cleaning Process Observation 19 50% methoxy-nonafluoro- 10 minutes boil Paste hardly removed with butane HFE7100 and significant residue left behind. 50% TDE. (HFE, HHC) 20 52.7% methoxy-nonafluoro- 10 minutes boil Some lifting of the residue butane HFE7100 and around the solder bumps but 44.6% TDE. not much removal. 2.7% ethanol (HFE, HHC, ALC) 21 52.7% methoxy-nonafluoro- 10 minutes boil/ Piece completely clean and butane HFE7100 and 1 minute rinse with metal and solder brightened. 44.6% TDE. HFE71DA 2.7% ethanol 3% Rhodafac RS710 (HFE, FAPE)

(23) Trial 21 of Example 4 shows that the same satisfactory results of Trial 18 of Example 3 are obtained with hydrofluoroethers as the base component of a free acid phosphate ester. The results of Trials 19 and 20 using hydrofluoroethers are comparable to those of Trials 16 and 17 of Example 3.

Example 5. NPB (n-Propylbromide) with Alcohol and Free Acid Phosphate Ester Used to Clean No-Clean Solder Pastes as the Soiling Substance

(24) TABLE-US-00005 Cleaning Formulation Trial (Component Type) Cleaning Process Observation 22 100% NPB (n-propyl 10 minutes boil Large amount of gray solids bromide) remain. (HHC) 23 95% NPB (n-propyl 10 minutes boil A little more residue removed bromide) than was removed in Trial 22. 5% isopropanol (HHC, ALC) 24 94.5% NPB (n-propyl bro- 10 minutes boil/ Piece completely clean and metal mide) 1 minute rinse with and solder brightened. 5% isopropanol NPB. 0.5% Rhodafac RS710 (HHC, ALC, FAPE)

(25) Trial 24 of Example 5 shows that the same results as obtained in Trial 21 of Example 4 are obtained using brominated solvents as the base component.

Example 6. HFC (Hydrofluorocarbon Organic Solvent with Alcohol and Free Acid Phosphate Ester Used to Clean No-Clean Solder Pastes as the Soiling Substance

(26) TABLE-US-00006 Cleaning Formulation Trial (Component Type) Cleaning Process Observation 25 50% Vertrel XF 10 minutes boil/ Large amounts of gray residue 50% dipropylene glycol 2 minutes rinse in around solder bumps. monomethyl ether XF (HHC, NHH) 26 52% Vertrel XF 10 minutes boil/ Paste mostly removed but 43% dipropylene glycol 2 minutes rinse in some white residue left. Slight monomethyl ether Vertrel XF improvement in cleaning as 5% benzyl alcohol compared to Trial 25. (HHC, ALC) 27 Trial 26 composition 10 minutes boil/ Piece completely clean and metal with 3% Capstone FS- 2 minutes rinse in and solder brightened. 66 added, with Ver- Vertrel XF trel XF reduced to 50% and the ether re- duced to 42%. (HHC, ALC, FAPE)

(27) Trial 27 of Example 6 illustrates the successful use of an organic solvent instead of TDE (Trans-Dichloroethylene) used in earlier fluorinated systems to remove or soften the rosin portion of the flux. Trial 27 also shows that the addition of alcohol and free acid phosphate ester provided a composition which successfully fully removed no-clean fluxes.

(28) The following examples A-H each describe a range of ingredients and quantities of various cleaning solvent compositions in accordance with aspects of the present invention. Specific compositions used in some of the Trials described above were selected from these examples, the compositions of which are defined in the indicated claims.

Example A

(29) The composition of Trial 6 was selected from this example.

(30) TABLE-US-00007 Weight Percent of the Ingredient Composition Halogenated Hydrocarbon Solvent about 50 to about 96 one or both of trans-chlorodifluormethyl propene and cis-chlorodifluoromethyl propene Alcohol about 2 to about 15 one or more straight and branched chain alkyl alcohols, aromatic and heteroaromatic alcohols, all having from 1-20 carbon atoms Phosphate Ester Surfactant (Acid Form) about 0.2 to about 15 one or more of alkoxylated alkyl and aryl substituted phosphate esters, alkoxylated phosphate esters, fluorinated alkyl and aromatic phosphate esters, and alkyl and aromatic substituted phosphate esters

Example B

(31) The composition of Trial 7 was selected from this example.

(32) TABLE-US-00008 Weight Percent of the Ingredient Composition Halogenated Hydrocarbon Solvent about 92 to about 96 trans-chlorodifluormethyl propene Alcohol about 2 to about 4 methanol Phosphate Ester Surfactant (Acid Form) about 2 to about 4 a fluorinated alkyl-substituted phosphate ester

Example C

(33) The composition of Trials 13 and 18 was selected from this example.

(34) TABLE-US-00009 Weight Percent of the Ingredient Composition Halogenated Hydrocarbon Solvent about 96 to about 98 a blend of from about 66 to about 68 weight percent of trans-dichloroethylene, about 17 to about 19 weight percent of 2,3-dihydro- decafluoropentane, about 11 to about 13 weight percent of heptafluorocyclopentane and about 1 to about 4 weight percent methanol Alcohol The alcohol is included in the halogenated hydrocarbon solvent blend. Phosphate Ester Surfactant (Acid Form) about 2 to about 4 an ethoxylated alkyl-substituted phosphate ester

Example D

(35) The composition of Trial 15 was selected from this example.

(36) TABLE-US-00010 Weight Percent of the Ingredient Composition Halogenated Hydrocarbon Solvent about 96 to about 98 a blend of about 40 to about 44 weight per- cent of trans-dichloroethylene, about 17 to about 19 weight percent of the hydrofluoro- carbon 1,1,1,3,3-pentafluorobutane (HFC 365), from about 36 to about 38 weight per- cent dihydrodecafluoropentane and from about 3 to about 4 weight percent methanol Alcohol The alcohol is included in the halogenated hydrocarbon solvent blend. Phosphate Ester Surfactant (Acid Form) about 2 to about 4 an ethoxylated alkyl-substituted phosphate ester

Example E

(37) The composition of Trial 21 was selected from this example.

(38) TABLE-US-00011 Weight Percent of the Ingredient Composition Halogenated Hydrocarbon Solvent about 94 to about 98 a blend of from about 51 to about 56 weight percent hydrofluoroether selected from one or more of methoxy-nonafluorobutane, eth- oxy-nonafluorobutane, 2-trifluoromethyl-3- ethoxydodecofluorohexane and 3-ethoxy- 1,1,1,2,3,4,4,5,6,6,6-dodecafluoro-2- trifluoromethyl-hexane, about 42 to about 48 weight percent trans-dichloroethylene and about 2 to about 4 weight percent eth- anol Alcohol The alcohol is included in the halogenated hydrocarbon solvent blend. Phosphate Ester Surfactant (Acid Form) about 2 to about 4 an ethoxylated alkyl-substituted phosphate ester

Example F

(39) The composition of Trial 24 was selected from this example.

(40) TABLE-US-00012 Weight Percent of the Ingredient Composition Halogenated Hydrocarbon Solvent about 70 to about 97 n-propyl bromide Alcohol about 4 to about 25 isopropanol Phosphate Ester Surfactant (Acid Form) about 0.4 to about 0.5 an ethoxylated alkyl-substituted phosphate ester

Example G

(41) The composition of Trial 27 was selected from this example.

(42) TABLE-US-00013 Weight Percent of the Ingredient Composition Halogenated Hydrocarbon Solvent about 48 to about 54 one or more hydrofluorocarbons Alcohol about 4 to about 6 benzyl alcohol Phosphate Ester Surfactant (Acid Form) about 2 to about 4 a fluorinated alkyl-substituted phosphate ester Non-Halogenated Hydrocarbon Solvent About 36 to about 44 dipropylene glycol monomethyl ether

Example H

(43) One or more of methanol, ethanol, isopropanol and n-butanol is substituted for the alcohol component of Examples A-G.

(44) While the invention has been described in detail with reference to specific embodiments, it will be appreciated that numerous variations may be made to the described embodiment, which variations nonetheless lie within the scope of the present invention.