Cleaning formulations

Abstract

A glycol ether-containing aqueous cleaning composition for use in cleaning a substrate surface, such as a surface of a printed circuit board during a manufacturing process, comprising: (a) at least one glycol ether having a high boiling point and low VOC; (b) at least one organic amine; (c) at least one surfactant; and (d) water; a process for making the glycol ether-containing aqueous composition; and a process for cleaning a printed circuit board using the composition.

Description

[Technical field]

[0001] The present invention relates to cleaning formulations, more particularly, the present invention relates to glycol ether-containing water-based compositions that can be used as cleaning formulations in electronics processing applications, for example, to clean solder flux and photoresist during printed circuit board manufacturing. [Background technology]

[0002] The manufacture of printed circuit boards (PCBs) requires multiple procedures, including mandatory cleaning steps. In current cleaning formulations, low molecular weight solvents are widely used as cleaning agents. These solvents are considered volatile organic compounds, or VOCs, due to their low molecular weight and corresponding low boiling point. With increasing environmental protection regulations, safer, halogen-free, non-VOC or low-VOC solvents are required in the printed circuit board (PCB) industry for use in cleaning formulations. In addition to VOC content, the ability of the solvent to effectively clean the board and provide a high-purity solvent (colorless, low residue content and low impurity profile) are also required criteria for solvents provided to the PCB industry.

[0003] PCB cleaning formulations and ingredients are well known in the electronics industry. For example, various flux removal cleaning formulations are mentioned in Japanese Patent Nos. 04776710(B2), 06458964(B2), 05945914(B2), JP 2003064397(A), U.S. Patent Nos. 7288511(B2), 6689734(B2), 5547601(A), Chinese Patent Publication Nos. 111171974(A), 110373283(A), 109837145(A), 103013704(A), and WO 1993016160(A1). Various photoresist cleaning formulations for removing photoresist from PCBs are also known in the art, for example as described in Patent No. 04570786(B2), US Patent No. 7579308(B2), US Patent No. 7288511(B2), US Patent No. 6689734(B2), Canadian Patent No. 1285463(C), and Chinese Patent Publication No. 107942624(A). In addition, US Patent No. 8444768(B2) refers to a cleaning formulation used in flux removal and PCB cleaning. The cleaning formulation of US Patent No. 8444768(B2) consists of 40-97% by weight of a solvent including glycol ether, 2-60% by weight of an additive including an acid-based surfactant and an amine (e.g., alkanolamine). The formulation of US Patent No. 8444768(B2) is diluted with water, acetone, or alcohol.

[0004] It would be desirable to have new cleaning formulations that have desirable properties for use in cleaning applications, such as use by the PCB industry to clean PCBs. Summary of the Invention

[0005] The present invention relates to a glycol ether containing water-based (GEWB) cleaning formulation that can be used to effectively clean solder flux and photoresist during PCB manufacturing. The GEWB cleaning formulation can provide good dissolution of solutes including rosin flux and phenolic photoresist.

[0006] In some embodiments of the present invention, a GEWB cleaning formulation for cleaning solder flux and photoresist during a PCB manufacturing process comprises a GEWB cleaning formulation including: (a) at least one glycol ether; (b) at least one organic amine; (c) at least one surfactant; and (d) water.

[0007] Another embodiment of the present invention includes a process for preparing the above GEWB composition.

[0008] In yet another embodiment, the present invention includes a cleaned PCB prepared by contacting an uncleaned PCB containing a first amount of contaminants thereon with a GEWB cleaning formulation described above to reduce the amount of contaminants on the uncleaned PCB to a second, reduced amount of contaminants, thereby forming a cleaned PCB containing a reduced level of contaminants thereon. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] Specific embodiments of the present application are described herein below. These embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the claimed subject matter to those skilled in the art.

[0010] Unless otherwise stated, or implicit from the context, or customary in the art, all percentages, parts, ratios, and similar amounts are defined by weight, i.e., based on weight. Parts and percentages are based on weight. For example, all percentages described herein are weight percentages (wt%) unless otherwise indicated. Also, all test methods disclosed herein are current as of the filing date of this disclosure.

[0011] Temperatures used herein are in degrees Celsius (°C).

[0012] As used herein, "room temperature (RT)" and "ambient temperature" mean a temperature between 20° C. and 26° C., unless otherwise specified.

[0013] As used herein, the term "composition" refers to a mixture of materials that comprise the composition, as well as reaction products and decomposition products formed from the materials of the composition.

[0014] "VOC" stands for volatile organic compounds.

[0015] With respect to organic solvents such as glycol ethers, the term "low VOC" content, as used herein, means that the organic solvent has a boiling point of 250° C. or greater, a vapor pressure of less than 10 Pa at 20° C., and / or a GC elution of 20% or less of the compounds at a time longer than the retention time of tetradecane (C14) as a GC elution retention time marker.

[0016] With respect to water-based compositions, "glycol ether-containing" as used herein means that the amount of glycol ether in the water-based composition is greater than 0%.

[0017] With respect to diluted glycol ether-containing compositions, "water-based" as used herein means that the dosage of water in the diluted glycol ether-containing composition is at least 50% or more.

[0018] By "high purity solvent" or "high solvent purity" in reference to organic solvents is meant herein a solvent having a color value of APHA less than 100. Also, by "colorless" in reference to organic solvents is meant herein a solvent having a color value of less than 100 APHA.

[0019] With respect to organic solvents, "low residual content" means herein a solvent having a residual base content of less than 0.01% by weight titrated as sodium hydroxide.

[0020] With respect to organic solvents, "low impurity profile" as used herein means that the solvent contains greater than 95% glycol ether oligomers.

[0021] The terms "comprising," "including," "having," and their derivatives are not intended to exclude the presence of any additional components, steps, or procedures, whether specifically disclosed or not. For the avoidance of any doubt, all compositions claimed through the use of the term "comprising" may include any additional additives, adjuvants, or compounds, whether polymeric or otherwise, unless otherwise stated to the contrary. In contrast, the term "consisting essentially of" excludes from the scope of any subsequent recitation any other component, step, or procedure, excepting those that are not essential to operability. The term "consisting of" excludes any component, step, or procedure not specifically described or listed. The term "or" refers to the listed items individually as well as in any combination, unless expressly stated otherwise. The use of the singular includes the use of the plural, and vice versa.

[0022] Numerical ranges disclosed herein include all values ​​between the lower limit and the upper limit (inclusive). Ranges containing explicit values ​​(e.g., ranges 1, or 2, or 3-5, or 6, or 7) include any subranges between any two explicit values ​​(e.g., the range 1-7 above includes the subranges 1-2, 2-6, 5-7, 3-7, 5-6, etc.).

[0023] As used throughout this specification, the following abbreviations have the following meanings unless the context clearly dictates otherwise: "=" means "equal to" or "equal to", "<" means "less than", ">" means "greater than", "≦" means "less than or equal to", "≧" means "greater than or equal to", "@" means "at", ppm = parts per million, "MT" = metric ton, g = grams, mg = milligrams, Kg = kilogram, L = liter, g / L = grams per liter, μL = microliter, "g / cm 3" or "g / cc" = grams per cubic centimeter, mg / mL = milligrams per milliliter, "kg / m 3 = kilograms per cubic meter, rpm = revolutions per minute, m = meters, mm = millimeters, cm = centimeters, μm = microns or micrometers, nm = nanometers, min = minutes, s = seconds, ms = milliseconds, hr = hours, Pa = pascals, Mpa = megapascals, kPa = kilopascals, Pa·s = pascal seconds, mPa·s = millipascal seconds, g / mol = grams per mole, g / eq = grams per equivalent, Mn = number average molecular weight, Mw = weight average molecular weight, pts = parts by weight, 1 / s or second -1 = reciprocal of seconds [s -1 ], °C = degrees Celsius, °C / min = degrees Celsius per minute, psi = pounds per square inch, kPa = kilopascals, % = percent, cal / mole = calories / mole, vol% = volume percent, mol% = mole percent, and wt% = weight percent.

[0024] Generally, GEWB cleaning compositions or formulations useful for cleaning solder flux and photoresist during the PCB manufacturing process include (a) at least one or more glycol ethers. Examples of glycol ethers that can be used are triethylene glycol methyl ether, tetraethylene glycol methyl ether, pentaethylene glycol methyl ether, hexaethylene glycol methyl ether, heptaethylene glycol methyl ether, octaethylene glycol methyl ether, triethylene glycol ethyl ether, tetraethylene glycol ethyl ether, pentaethylene glycol ethyl ether, hexaethylene glycol ethyl ether, heptaethylene glycol ethyl ether, octaethylene glycol ethyl ether, triethylene glycol propyl ether, tetraethylene glycol propyl ether, pentaethylene glycol propyl ether, hexaethylene glycol propyl ether, heptaethylene glycol propyl ether, octaethylene glycol propyl ether, triethylene glycol butyl ether, tetraethylene glycol butyl ether, pentaethylene glycol butyl ... Liquor butyl ether, heptaethylene glycol butyl ether, octaethylene glycol butyl ether, tripropylene glycol methyl ether, tetrapropylene glycol methyl ether, pentapropylene glycol methyl ether, hexapropylene glycol methyl ether, heptapropylene glycol methyl ether, octapropylene glycol methyl ether, tripropylene glycol ethyl ether, tetrapropylene glycol ethyl ether, pentapropylene glycol ethyl ether, hexapropylene glycol ethyl ether, heptapropylene glycol ethyl ether, octapropylene glycol ethyl ether, tripropylene glycol propyl ether, tetrapropylene glycol propyl ether, pentapropylene glycol propyl ether, hexapropylene glycol propyl ether, heptapropylene glycol propyl ether, octapropylene glycol propyl ether, tripropylene glycol butyl ether,Tetrapropylene glycol butyl ether, pentapropylene glycol butyl ether, hexapropylene glycol butyl ether, heptapropylene glycol butyl ether, octapropylene glycol butyl ether, and mixtures thereof.

[0025] In some preferred embodiments, the glycol ether may be, for example, (1) a mixture of two or more of the following components: tripropylene glycol propyl ether, tetrapropylene glycol propyl ether, pentapropylene glycol propyl ether, hexapropylene glycol propyl ether, heptapropylene glycol propyl ether, and octapropylene glycol propyl ether; or (2) a mixture of two or more of the following components: tripropylene glycol butyl ether, tetrapropylene glycol butyl ether, pentapropylene glycol butyl ether, hexapropylene glycol butyl ether, heptapropylene glycol butyl ether, and octapropylene glycol butyl ether.

[0026] In some embodiments, the glycol ether, component (a) of the present invention, has a boiling point (at a pressure of 101.3 kPa and a temperature of 25° C.) of 250° C. to 350° C. in one typical embodiment, 250° C. to 300° C. in another typical embodiment, and 250° C. to 280° C. in yet another typical embodiment. The boiling point of the glycol ether can be determined using the method described in ASTM D1078-03.

[0027] The volatile organic compounds (VOCs) of the glycol ethers of the present invention may depend on various factors, such as boiling point, vapor pressure, and molecular weight. EU Directive 2004 / 42 / EC defines VOCs as any organic compound having a boiling point of ≦250° C. at standard pressure, and the VOC content is measured by GC analysis according to ISO11890-2. The GC marker used to measure the relative boiling point is tetradecane, which has a boiling point of 253.6° C. Based on the above method for determining VOC content, the criterion used herein to determine the VOC content of the glycol ethers of the present invention is boiling point, and the glycol ethers of the present invention have a boiling point within the above range.

[0028] In some embodiments, the glycol ether that is component (a) of the present invention has a molecular weight (Mw) of 170 to 550 in one typical embodiment, 180 to 500 in another embodiment, and 190 to 490 in yet another embodiment.

[0029] In some embodiments, the glycol ethers that are component (a) of the present invention have a hydroxyl number of from 220 to 320 in one typical embodiment, from 250 to 300 in another embodiment, and from 270 to 285 in yet another embodiment. The hydroxyl number of the glycol ethers can be determined using the method described in ASTM D1899-02.

[0030] In some embodiments, the glycol ethers that are component (a) of the present invention generally have the following, using the methods described in the Examples herein below: (1) 13.0 J / cc 1 / 2 ~15.5J / cc 1 / 2 Dispersion Hansen solubility parameter, (2) 0.5 J / cc 1 / 2 ~3.0J / cc 1 / 2 Polar Hansen solubility parameter of (3) 6.5 J / cc 1 / 2 ~8.5J / cc 1 / 2 Hydrogen bond Hansen solubility parameters of

[0031] The concentration of glycol ether present in the GEWB cleaning formulation may be from 1% to 75% by weight in one broad embodiment. When the GEWB cleaning formulation is used, for example, as a photoresist cleaner, the glycol ether may be present in the photoresist cleaner at a concentration ranging from 5% to 50% by weight in one typical embodiment, from 10% to 40% by weight in another embodiment, and from 15% to 30% by weight in yet another embodiment, based on the total weight of all components in the composition. In other embodiments, when the GEWB cleaning formulation is used, for example, as a flux remover, the concentration of glycol ether in the flux remover may be within the range of 20% to 70% by weight in one typical embodiment, from 25% to 60% by weight in another embodiment, and from 30% to 50% by weight in yet another embodiment, based on the total weight of all components in the composition.

[0032] Component (b) of the composition of the present invention is at least one pH adjuster, such as an organic amine pH adjuster, such as monoethanolamine, diethanolamine, triethanolamine, monoisopropanolamine, dipropanolamine, tripropanolamine, β-aminoisobutyl alcohol, other similar alcohol amines, and mixtures thereof.

[0033] In one preferred embodiment, component (b) of the compositions of the present invention comprises, consists essentially of, or consists of monoethanolamine, monoisopropanolamine, and mixtures thereof.

[0034] Component (b), an organic amine, is advantageously used to modify the pH of the GEWB cleaning formulation of the present invention, and the amount of organic amine in the GEWB cleaning formulation should be sufficient to modify the pH of the formulation. For example, the concentration of organic amine useful in the compositions of the present invention can be from 1% to 15% by weight in one typical embodiment, and from 3% to 10% by weight in another embodiment, based on the total weight of all components in the composition.

[0035] The component (c) of the composition of the present invention is at least one surfactant.In some embodiments, the surfactant of component (c) can include anionic surfactants, cationic surfactants, and nonionic surfactants, and mixtures thereof.For example, in some embodiments, the surfactant is an anionic surfactant, such as at least one of dodecylbenzenesulfonic acid, diethanolamine oleate, triethanolamine oleate, triethanolamine dodecylbenzenesulfonic acid, ethanolamine lauryl sulfate, and mixtures thereof.

[0036] For example, in some embodiments, the surfactant is a non-ionic surfactant such as at least one of higher alcohol polyoxyethylene ethers, alkylphenol polyoxyethylene ethers, fatty acid alkanolamides, coconut oil fatty acid diethanolamides, and the like, having a narrow distribution of HLB (hydrophile-lipophile balance) values ​​of 10-14.

[0037] Advantages of adding component (c), a surfactant, to the composition of the present invention include, for example, (1) the surfactant increases the emulsification or dispersion of solutes, including photoresists, rosins, and solder fluxes, thereby increasing the suspension and stability of the composition.

[0038] The concentration of surfactant useful in the compositions of the present invention may be from 0.01% to 10% by weight in one typical embodiment, from 0.1% to 8% by weight in another embodiment, and from 0.5% to 5% by weight in yet another embodiment, based on the total weight of all components in the composition.

[0039] Component (d) of the compositions of the present invention is water. Any source of water can be used, including, for example, tap water, deionized (DI) water, and the like, and mixtures thereof.

[0040] The amount (dosage) of water useful in the compositions of the present invention for the function of diluting the glycol ether-containing composition can be at least 50% by weight in one typical embodiment, 50% to 99% by weight in another embodiment, 50% to 90% by weight in yet another embodiment, 50% to 80% by weight in yet another embodiment, and 50% to 70% by weight in still yet another embodiment, based on the total weight of all components in the composition.

[0041] If desired, the composition of the present invention may be formulated with a wide variety of additives to enable the performance of specific functions while maintaining the excellent advantages / properties of the composition of the present invention. For example, the optional additives that are component (e) useful in the formulation of the present invention may be selected from corrosion inhibitors, water, antioxidants, and mixtures thereof.

[0042] In one preferred embodiment, optional additives may be added to the compositions of the present invention, such as corrosion inhibitors, such as citric acid, lauric acid, and mixtures thereof.

[0043] The optional compounds, when used in the compositions of the present invention, may generally be present in an amount ranging from 0% to 0.1% by weight in one embodiment, from 0.01% to 0.05% by weight in another embodiment, and from 0.01% to 0.03% by weight in yet another embodiment.

[0044] In one broad embodiment, the process for making the GEWB cleaning formulation of the present invention includes, for example, mixing, admixing, or blending (a) at least one glycol ether, (b) at least one organic amine, (c) at least one surfactant, and (d) water to form a GEWB cleaning formulation, which has improved properties as described herein below. If desired, one or more additional optional components, component (e), may be added to the formulation. For example, components (a), (b), (c), and (d) may be mixed together in the desired concentrations described above and at a temperature of 20°C to 50°C in one embodiment, and 25°C to 35°C in another embodiment. If desired, optional additive component (e) may be mixed with any one or more of components (a), (b), (c), and / or (d). The order of mixing the components is not important, and the remaining components may be added after two or more components are mixed together. The components of the formulation can be mixed together by any conventional mixing process and equipment known to those skilled in the art of mixing.

[0045] In another embodiment, the process for making the GEWB cleaning formulation of the present invention comprises: (I) providing at least one first glycol ether solvent having a contaminant content of 1 weight percent or greater and / or a color value of greater than 100 APHA; (II) purifying the at least one first glycol ether solvent to form at least one second purified glycol ether solvent having a color of less than 100 APHA and having less than 0.01 wt. % base titrated as sodium hydroxide; (III) providing the following components: (a) at least one purified second glycol ether from step (II) having a high boiling point and low VOC; (b) at least one pH adjuster component, such as an organic amine; (c) at least one surfactant; and (d) water; (IV) mixing the components of step (III).

[0046] In step (II) of the above process, it is desirable to remove as much sodium as possible so that the sodium does not form a residue on the surface of the electronic PCB.

[0047] In step (III) of the above process, in some preferred embodiments, the at least one purified second glycol ether from step (II) has a boiling point of 250° C. or higher and a low VOC in terms of vapor pressure of less than 10 Pa at 20° C.

[0048] After combining components (a)-(c) in step (IV) of the above process, the resulting GEWB cleaning formulation formed by the above process has good (increased) solute solubility and good water solubility properties.

[0049] The GEWB cleaning formulations of the present invention produced by the above process have several advantageous properties and / or benefits compared to known formulations. For example, some of the properties / benefits exhibited by the compositions of the present invention can include, for example: (1) The glycol ethers used to form the GEWB cleaning formulations of the present invention are water-dilutable solvents, which are preferred ingredients for producing cleaning formulations, especially when water is used instead of other organic diluent chemicals to dilute the formulation. (2) The glycol ethers have high molecular weights (e.g., the number of carbon atoms in the glycol ether is greater than 9), e.g., glycol ethers of propoxylates of butanol and propanol, which provide non-VOC or low-VOC compositions. (3) The GEWB cleaning formulations of the present invention do not contain harmful components such as monobrominated hydrocarbons (e.g., halogenated solvents). (4) The glycol ethers used in the GEWB cleaning formulations of the present invention have a cleaning function rather than an emulsifying function. (5) The chemical structure of the GEWB cleaning formulations of the present invention is simple rather than complex. (6) The glycol ether products have a broad high molecular weight distribution, which is therefore better since the glycol ether products are non-VOC. (7) The GEWB cleaning formulation of the present invention is better because the glycol ether starts from an alcohol structure instead of a pure ethylene oxide based solvent, and therefore improves the solubility of solutes used in PCB processing when used with the GEWB cleaning formulation of the present invention. (8) The residue of contaminants formed on the PCB is low because of this glycol ether, and if residue is formed, it can be easily removed by rinsing the residue with water, alcohol, or ketone.

[0050] For example, the water solubility of the composition of the present invention may generally be in the range of 4% by weight to 90% by weight in one embodiment, 20% by weight to 70% by weight in another embodiment, and 30% by weight to 50% by weight in yet another embodiment.

[0051] The cleaning formulations of the present invention can be used in electronic applications, such as, for example, to clean electronic materials such as PCBs, transistors, chips, and other electronic elements including capacitors, conductive circuits, displays, amplifiers, and the like.

[0052] In a preferred embodiment, the GEWB formulation of the present invention can be used, for example, to clean solder flux and photoresist during the manufacturing process of PCBs. To clean PCBs, various methods such as spray and ultrasonic methods known to those skilled in the art can be used.

[0053] For example, in some embodiments, the process for cleaning PCBs using the GEWB cleaning formulation of the present invention comprises: (1) preparing a GEWB cleaning formulation; (2) contacting the PCBs with the GEWB cleaning formulation by spraying the GEWB cleaning formulation in liquid form; (3) rinsing the PCBs from step (2) with water; and (4) drying the water-rinsed PCBs from step (3) at room temperature or elevated temperature.

[0054] For example, in another embodiment, the process for cleaning a PCB using a GEWB cleaning formulation of the present invention comprises: (1) preparing a GEWB cleaning formulation; (2) contacting the PCB with the GEWB cleaning formulation by placing the PCB in an ultrasonic bath of the GEWB cleaning formulation in liquid form; (3) removing the PCBs from step (2) from the ultrasonic bath; (4) rinsing the PCBs from step (3) with water; and (5) drying the water-rinsed PCBs from step (4) at room temperature or elevated temperature.

[0055] Some of the advantages of the cleaned PCBs of the present invention prepared by the above process of the present invention include, for example: (1) the cleaned PCBs of the present invention have a longer service life compared to uncleaned PCBs. (2) the cleaned PCBs of the present invention cleaned by the process of the present invention using a low VOC solvent have a longer or the same service life than a PCB cleaned by a conventional method using a solvent with a significant content of VOCs. (3) the cleaned PCBs of the present invention have increased operational stability compared to uncleaned PCBs. (4) the cleaned PCBs of the present invention cleaned by the process of the present invention using a low VOC solvent have a longer or the same operational stability than a PCB cleaned by a conventional method using a solvent with a significant content of VOCs. In some embodiments, the above advantages may be exhibited by the cleaned PCBs of the present invention prepared by the process of the present invention even when the cleaned PCBs of the present invention are compared to other cleaned PCBs prepared using non-VOC-containing solvents. EXAMPLES

[0056] The following inventive examples (Inv. Ex.) and comparative examples (Comp. Ex.) (collectively "Examples") are presented herein to more fully illustrate the features of the present invention, but are not intended to be construed, either explicitly or implicitly, as limiting the scope of the claims. Inventive examples are identified by Arabic numerals, and comparative examples are represented by alphabetical letters. The following experiments analyzed the performance of embodiments of the compositions described herein. Unless otherwise indicated, all parts and percentages are by weight based on total weight.

[0057] name Various terms, names and abbreviations used in the Examples are defined herein as follows:

[0058] "PCB" stands for printed circuit board.

[0059] "MEA" stands for monoethanolamine.

[0060] "MPG" stands for methoxypolyethylene glycol.

[0061] "Purified" with respect to a compound means that the compound has been subjected to a purification process, such as distillation or evaporation, to remove undesirable residues relative to the original compound and to reduce the amount of contaminants present in the original compound to less than 0.01% by weight. For example, if an original product of MPG has about 2% by weight of impurities, and the MPG is purified to reduce the original amount of impurities to less than 0.01% by weight, the resulting product is called "purified MPG."

[0062] "BPG" stands for butoxypolyethylene glycol.

[0063] "Purified BPG" means a butoxy polyethylene glycol product having an undesirable residual base content of less than 0.01% by weight and an APHA of the purified / purified butoxy polyethylene glycol n-propyl ether product of less than 100.

[0064] "PolyPnB" stands for polypropylene glycol n-butyl ether.

[0065] "Purified PolyPnB" means a polypropylene glycol n-butyl ether product having an undesirable residual base content of less than 0.01% by weight and an APHA of the purified / purified polypropylene glycol n-butyl ether product of less than 100.

[0066] "PolyPnP" stands for polypropylene glycol n-propyl ether.

[0067] "Purified PolyPnP" means a polypropylene glycol n-propyl ether product having no undesirable residual base content of less than 0.01% by weight and the APHA of the purified / purified polypropylene glycol n-propyl ether product is less than 100.

[0068] raw material Table I lists the ingredients, including glycol ethers, organic amines and surfactants, used in the examples to prepare the GEWB cleaning formulations for cleaning solder flux and photoresist during the PCB manufacturing process.

[0069] [Table 1]

[0070] Volatile Organic Compound (VOC) Content Depending on the specific application and region in which the solvent is used, the solvent content in the formulation is subject to Volatile Organic Compound (VOC) content constraints under various different environmental regulations around the world. These changing regulations are aimed at improving both indoor and outdoor air quality control. There are several definitions of VOCs, as volatility depends on factors such as boiling point, vapor pressure, and molecular weight. EU Directive 2004 / 42 / EC defines VOCs as any organic compound with a boiling point ≤ 250°C at standard pressure, and VOC content is measured by GC analysis according to ISO 11890-2. The GC marker used to measure relative boiling point is tetradecane, which has a boiling point of 253.6°C.

[0071] Purified glycol ethers were prepared using a customized UIC RFT-6 laboratory roll film distillation apparatus or wiped film distillation apparatus (WFE). A 316 stainless steel evaporator with an internal evaporation area of ​​0.06 square meters was set at the desired processing temperature and placed under vacuum. The feed material to the WFE was dosed using a Mahr Feinpruf Model N19 0.6 spinning pump delivering at a rate of 0.66 cc / rev. Vapors exiting the evaporation section were condensed in a glass condenser with a surface area of ​​0.3-0.6 square meters cooled with tap water. The bottom residue was collected at the bottom of the evaporator body.

[0072] Preparation of purified MPG The above WFE was heated to 180°C and charged with 1,850.09g of methoxy polyglycol (basic) at a feed pump speed of 17 rpm and wiper spin speed of 300 rpm with a vacuum of 0.1 torr. The run was completed in 175 minutes with 1,601.13g of overhead product collected. The bottoms fraction weighed 200.79g. The color was less than 50 APHA and the average molecular weight was 212g / mole as determined by GC analysis.

[0073] Preparation of purified BPG The above WFE was heated to 200°C and charged with 716.74g of butoxy polyglycol (basic) at a feed pump speed of 14 rpm and wiper spin speed of 260 rpm at a vacuum of 0.3 torr. The run was completed in 105 minutes with 490.9g of overhead product collected. The bottom fraction weighed 201.46g. The color was less than 100 APHA and the average molecular weight was 262g / mole as determined by GC analysis.

[0074] Preparation of purified PolyPnB The above WFE was heated to 180°C and charged with 917.94g of basic PolyPnB at a feed pump speed of 17 rpm and wiper spin speed of 260 rpm at a vacuum of 0.1 torr. The run was completed in 95 minutes with 755.97g of overhead product collected. The bottom fraction weighed 140.90g. The color was less than 50 APHA and the average molecular weight was 292g / mole as determined by GC analysis.

[0075] Preparation of purified PolyPnP The above WFE was heated to 170°C and charged with 1142.50g of basic PolyPnP at a feed pump speed of 16 rpm and wiper spin speed of 260 rpm at a vacuum of 0.1 torr. The run was completed in 127 minutes with 938.2g of overhead product collected. The bottom fraction weighed 187.72g. The color was less than 50 APHA and the average molecular weight was 248g / mole as determined by GC analysis.

[0076] compound General Procedure for Preparing Defluxer Formulations A series of concentrated formulation samples were prepared containing the ingredients set forth in Table II, e.g., 40% by weight monoethanolamine, 20% by weight ECOSURF™ EH-6, and 40% by weight solvent. The concentrated formulations were then diluted with water.

[0077] [Table 2]

[0078] General Procedure for Preparing Rosin Dissolved Formulations A series of concentrated formulation samples used in the rosin dissolution testing were prepared containing the components listed in Table III.

[0079] Rosin powder and solvent were mixed in a 20 mL glass bottle. The mixture of rosin powder and solvent in the glass bottle was placed in an oven set at a temperature of 50° C. and heated. The mixture in the glass bottle was then shaken at 200 rpm for 20 minutes. The dissolution of the rosin, measured by weight in the solvent, was observed with the naked eye and recorded.

[0080] [Table 3]

[0081] General Procedure for Preparing Photoresist Cleaner Formulations A series of concentrated formulation samples used for cleaning photoresist were prepared containing the components listed in Table IV, for example, a cleaning formulation was prepared containing 20% ​​by weight of solvent, 20% by weight of monoethanolamine, 0.5% by weight of ECOSURF™ EH-6, and 59.5% by weight of water, with a total weight of 10 g. The formulations were stirred at 120 RPM and 60° C. using a magnetic stirrer. The resulting formulations are listed in Table IV.

[0082] [Table 4]

[0083] Testing and Measurement GC analysis GC (Gas Chromatography) analysis was performed on an Agilent 6890 GC instrument by injecting 1 μL of sample diluted approximately 50 / 50 by volume with methanol onto a 30 m×0.25 mm, 0.25 μm film ZB1 column at 100° C. and ramping at 10° C. / min to 300° C. The injector and thermal conductivity detector temperatures were 300° C. A constant helium pressure of 15 psig and a split ratio of 25:1 were used. Results were expressed using area percent integrals that were confirmed to represent weight percent composition.

[0084] molecular weight The average molecular weight was determined using the individual molecular weight of each oligomer along with the amount of each oligomer in the sample as determined by GC analysis.

[0085] The average molecular weights determined by GC analysis were consistent with those measured by hydroxyl titration.

[0086] Hydroxyl Number Hydroxyl number was measured according to ASTM D4274. An oven-dried Fisher Porter bottle was cooled with a stream of nitrogen and 3.00 grams of sample was weighed into the bottle, taking care not to allow any sample to stick to the sides of the bottle. The bottle was secured to a ring stand and 25 mL of phthalic anhydride-pyridine reagent (84 g phthalic anhydride / 600 mL anhydrous pyridine) was added. The bottle was sealed with a rubber septum secured with a cable tie. This procedure was repeated for two more samples and three blanks (only phthalic anhydride reagent was used for the blanks). All bottles were inserted into a bottle rack and placed in a 100°C water bath for one hour. After the time had elapsed, the rack was removed from the bath and the samples were allowed to cool to room temperature. The bottles were removed from the rack and secured on a stir plate. A stir bar was added and the stirrer was turned on to create a vortex. Five drops of phenolphthalein alcohol solution were added as an indicator. The samples were titrated with 1.00N NaOH to a light pink endpoint. This procedure was repeated for all samples. The Hydroxyl Number was calculated by the following formula: [[[(mL of blank NaOH)-(mL of sample NaOH)] x N number of NaOH solution] / sample weight] x 56.1

[0087] For monobasic alcohols such as these glycol ethers, the calculated molecular weight was 1,700 / (%OH). The hydroxyl number was 32.9. * (%OH).

[0088] Hansen Solubility Parameter Hansen Solubility Parameters (HSP) of the Butyl-PO and Propyl-PO pure components were calculated using correlations based on inverse molar volume regressions as described in Hansen Solubility Parameters-A User's Handbook, CRC Press, Boca Raton, 1999, 2007.

[0089] The HSPs for the remaining pure components were calculated using the Yamamoto Molecular Break (YMB) method described in the commercially available HSPiP program (version 4, 4.1.07) using group contribution parameters and SMILES structures. The HSPiP program can be found at the website (https: / / usd.swreg.org / com).

[0090] color Color was measured using a HunterLab ColorQuest XT colorimeter calibrated according to ASTM D 4890 and reported using the APHA scale known to those skilled in the art. APHA (American Public Health Association) color refers to Hazen Unit Color or Platinum / Cobalt (Pt / Co) Unit Color, which is a measure of yellowness defined by ASTM D1209.

[0091] Base Concentration Base concentrations were determined by diluting 0.1 g to 5 g samples with aqueous 2-propanol and titrating with 0.0100 N hydrochloric acid using a calibrated Mettler Toledo DL70 Autotitrator. Results are reported as weight % NaOH.

[0092] Boiling Point Calculation The boiling points of the various refined WFE products listed above were calculated using the LIQACT program available in the CHEMCOMP™ Solvent Modeling Property Service and area percent compositions obtained from GC analysis. The LIQACT program uses UNIFAC parameters to estimate activity coefficients for various phase equilibrium calculations. Calculations for multicomponent mixtures can be performed using this program, which requires Antoine constants and the UNIFAC equation for each component in the mixture. Antoine constants were retrieved from the CHEMCOMP™ solvent database and PCPROP property databank, when available.

[0093] Antoine constants for higher homologues (e.g., ≥ 5-9 EO or PO units) were not available and had to be derived in a two-step process. First, the normal boiling point of the component of interest was extrapolated from a plot of boiling point vs. EO or PO units for a given glycol ether family (e.g., PnB homologues). This boiling point was then entered into the ANTOINE program (also available from CHEMCOMP™) from which the Antoine constant was processed following the procedure described in GWM Thomson; "The Antoine Equation for Vapor Pressure Data", Chem. Rev. (38), p. 1-39, February 1946, using the Thomson restraint option and a single-point calculation with the Thomson constant. The Trouton constant is known as the entropy of vaporization and is equal to the cal / mole of heat of vaporization (at the boiling point) divided by the boiling point in degrees Kelvin. The various glycol ether homologues were fitted to the following Trouton constants: PnP (24), methyl, ethyl, hexyl and PolyPG (26), and PNB and butyl (27).

[0094] Boiling Point Measurement In a typical experiment, 30 mL of WFE product was added to a 50 mL single neck round bottom flask (Kontes Bantam-ware) with a built-in thermocouple well. A small Teflon stir bar was added to the flask, which was then secured to a holder (hood lattice) in the fume hood with a clamp. A heating mantle was attached to the flask, and a magnetic stir plate was placed under the mantle. A control and high limit thermocouple leading from a digital temperature controller was placed between the mantle and the flask. Another thermocouple from a digital thermometer was placed inside the thermocouple well, which contained a few drops of glycerin for heat transfer purposes. A condenser with a drip port at the bottom of the cooling coil was attached to the flask, and an adapter connected to a nitrogen vacuum line with a vacuum tube was placed on top of the condenser. The flask was insulated to minimize heat loss. To facilitate pressure control, a Tescom back pressure regulator was placed in the main vacuum line between the vacuum pump and the low pressure (5 psig) nitrogen line, which had a pressure relief valve in place to protect against over pressurization of the glass apparatus. The nitrogen-vacuum line to the condenser was teed-off from the main vacuum line above the nitrogen line. A digital Rosemount gauge was placed on the end of the vacuum line above the tee to the condenser to read the actual pressure in the flask. The stir plate was rotated at a slow speed. Dry ice was added to the vacuum pump trap and the vacuum pump was turned on. The nitrogen flow was stopped and the pressure was adjusted to approximately 1.0 mmHg with the Tescom regulator fully open. Water was charged to the condenser and the flask was heated to approximately 200°C (external mantle temperature). When liquid was observed refluxing at the bottom of the condenser, the internal flask temperature and pressure were recorded. The pressure was then adjusted to the next desired value by opening the nitrogen flow and / or adjusting the Tescom regulator in the "increase" direction. The mantle temperature was gradually increased to 250°C, 300°C, and finally 325°C while increasing the pressure to obtain a range of vapor pressures. A total of 10-20 data points were collected.

[0095] The vapor pressure data was fitted to the Antoine equation of logP=AB / (T+C) using the CHEMCOMP™ Antoine program to obtain the three Antoine constants and normal boiling points. Thomson restraints were used in all vapor pressure fits.

[0096] Test results General Procedure for Testing Defluxer Formulations The solder flux was heated to 80°C, liquefied, and spread on the surface of the PCB metal circuit. The liquid solder flux on the surface of the PCB metal circuit froze when the temperature of the flux decreased to room temperature. A 4.5 g sample of the concentrated formulation of the flux cleaning formulation prepared above (formulation: 40 wt% monoethanolamine, 20 wt% ECOSURF™ EH-6, and 40 wt% solvent) was diluted with 30 g water. The PCB was then immersed in the diluted formulation. The PCB was cleaned using ultrasonics (90 Hz) at 45°C for 2 minutes. The test results of the flux remover formulation are listed in Table V.

[0097] [Table 5]

[0098] General Procedure for Determining "Clean" vs. "Residue" With reference to Table V, the PCB surface was visually observed for any residue (i.e., solder flux) remaining after undergoing the cleaning actions described above, and the surface area of ​​the PCB covered by residue after cleaning, if any, was recorded. If any residue was observed on the PCB metal circuits, or if more than 0.01% of the total PCB surface area had residue, the PCB was labeled as "Residue", indicating that some flux residue was present on the PCB metal circuits and the cleaning composition did not function adequately as a cleaning agent. On the other hand, if no residue was observed on the PCB metal circuits, or if it had residue on less than 0.01% of the total PCB surface area, the PCB was labeled as "Clean", indicating that no residue or only very small amounts of residue were present on the PCB metal circuits.

[0099] As an alternative to the above-described procedure for determining cleaned vs. residual PCBs, in some embodiments, a method for distinguishing between "cleaned" and "residue" PCBs can be performed by measuring the period of time required to completely remove any observable residue from the surface area of ​​the PCB. In this method, if the PCB is subjected to a cleaning process for a period of time of 120 seconds or less in one typical embodiment, and 30 seconds to 120 seconds in another embodiment, after which no residue is observed on the surface of the PCB (i.e., the residue is substantially completely removed from the surface area of ​​the PCB), the PCB is considered to be a "cleaned" PCB. Conversely, if the PCB is subjected to a cleaning process and the cleaning process takes longer than 120 seconds to reach a point where no residue is observed on the surface of the PCB (i.e., it takes longer than 120 seconds to substantially completely remove the residue from the surface area of ​​the PCB), the PCB is considered to be a "residue" PCB.

[0100] General Procedure for Testing Rosin Dissolving Formulations Rosin powder and solvent were mixed in a 20 mL glass bottle. The mixture of rosin powder and solvent in the glass bottle was placed in an oven set at a temperature of 50° C. and heated for 10 minutes. The mixture in the glass bottle was then shaken at 200 rpm for 20 minutes. The dissolution of the rosin was observed visually and measured by weight in the solvent and the results were recorded. The results of the rosin dissolution are shown in Table VI.

[0101] [Table 6] Notes to Table VI: * To determine rosin solubility, rosin was added incrementally at 0.01 wt% rosin in glycol ether. The wt% solubility was the cumulative weight of solids at solids saturation as determined by visual inspection.

[0102] General Procedure for Testing Photoresist Cleaner Formulations The flexible PCB sheet was placed in a cleaning formulation containing 20 wt% solvent, 20 wt% monoethanolamine, 0.5 wt% ECOSURF™ EH-6, and 59.5 wt% water, with a total weight of 10 g. The formulation was used to strip the PCB sheet for 2 minutes. After 2 minutes, water was used to rinse the PCB sheet surface, and then the PCB sheet was dried. The PCB sheet was then immersed in an ultra-roughening solution for 10 seconds. After the PCB sheet was placed in the roughening solution for 10 seconds, water was again used to rinse the PCB sheet surface. The PCB sheet was then dried again. The photoresist residue remaining on the surface of the flexible PCB sheet was observed with the naked eye and recorded. The photoresist cleaning results are shown in Table VII.

[0103] [Table 7] Notes to Table VII: * "Some Residue" means that a small amount of photoresist residue was observed to be present on the PCB, and the cleaning rate of this composition was not as fast as the other compositions marked "Clean."

[0104] For Table VII, the procedure used to determine whether a PCB was considered "cleaned," "residue," or "some residue" was the same procedure described above in "General Procedure for Determining 'Cleaned' vs. 'Residue'." However, for the examples in Table VII, a PCB with "some residue" means that the residue area of ​​the PCB was between 0.01% or more and less than 1% of the total PCB surface area. Also, "residue" means that the residue area of ​​the PCB was 1% or more of the total PCB surface area.

[0105] Discussion of results Flux remover Solvents useful for preparing the flux remover compositions include, for example, DOWAWNOL™ DPnB, TPnB, hexyl CARBITOL™, refined PolyPnP, and refined PolyPnB. DOWANOL™ DPnB and hexyl CARBITOL™ are industry standard compounds and are widely used in flux remover applications. Some of the properties of the solvents used in the examples are listed in Table VIII.

[0106] [Table 8] Notes for Table VIII: * "Cracked" means a compound that decomposes below its boiling point.

[0107] Some advantages of using purified PolyPnB as a solvent in this flux remover application include, for example, that the solvent has a high boiling point, which allows the temperature of the flux remover formulation to be increased, further accelerating the flux removal rate. DOWANOL™ TPnB solvent showed the same advantages as purified PolyPnB solvent. Purified PolyPnB, hexyl CARBITOL™, and DOWANOL™ TPnB solvents are non-VOC solvents, and therefore, these solvents can be used in this flux removal application in some countries that have implemented VOC limit regulations.

[0108] Rosin Solubility Solvents useful for solubilizing rosin include, for example, DOWANOL™ DPnB, TPnB, hexyl CARBITOL™, polyglycol P-425, purified PolyPnP, and purified PolyPnB. These solvents have rosin solubility values ​​greater than 6% by weight.

[0109] Photoresist Stripper Solvents useful for stripping photoresist include, for example, DOWANOL™ DPnB, TPnB, purified PolyPnP, and purified PolyPnB.

[0110] One of the several advantages of using purified PolyPnB as a solvent for stripping photoresist from PCBs is, for example, that the solvent has a high boiling point, which allows the temperature of the photoresist stripper formulation to be increased, further accelerating the photoresist removal rate. DOWANOL™ TPnB solvent showed the same advantages as purified PolyPnB solvent. Purified PolyPnB, hexyl CARBITOL™ and DOWANOL™ TPnB solvents are non-VOC solvents, and therefore these solvents can be used in this photoresist removal application in some countries that have implemented VOC limit regulations.

[0111] Solvents with lower polar Hansen solubility parameters used in flux removal and photoresist stripping perform more effectively than solvents with higher Hansen solubility parameters. Solvents with lower hydrogen bond Hansen solubility parameters can also improve the performance of the solvent. The rosin solubility value of a solvent is also highly related to the two parameters polar Hansen solubility parameter and hydrogen bond Hansen solubility parameter. A comparison of the solvents used in the examples is listed in Table VIII.

[0112] Although the solvent DOWANOL™ DPnB is considered a VOC material, its performance in the present invention is very good, whereas the solvent DOWANOL™ TPnB, which has a lower hydroxyl number, water miscibility, and formulation stability, performs less well.

[0113] Polyglycol P-425 solvent has a very high viscosity that reduces the interaction between the solute surface and the solvent. Therefore, the rosin dissolution evaluation for Polyglycol P-425 solvent is static and shows good results. However, when evaluating the dynamic process of flux removal and photoresist stripping, the performance of Polyglycol P-425 is negative because Polyglycol P-425 contains two hydroxyl groups in one molecule, which shows higher polarity, and as a result of the solvent having high polarity, the solvent is not very good at dissolving flux or photoresist.

Claims

1. 1. A glycol ether-containing aqueous composition for use as a cleaning formulation during a printed circuit board manufacturing process, comprising: (a) at least one glycol ether having a boiling point greater than 240° C. and a VOC content in terms of vapor pressure less than 10 Pa at 20° C.; (b) at least one organic amine; (c) at least one surfactant; (d) water.

2. 2. The composition of claim 1, wherein the at least one glycol ether has a boiling point at 101.3 kilopascals pressure of greater than 240°C to 350°C.

3. 2. The composition of claim 1, wherein the at least one glycol ether has an average molecular weight (Mw) of 170 to 550.

4. The composition of claim 1, wherein the at least one glycol ether has a hydroxyl number of from 220 to 320.

5. The at least one glycol ether has a dispersion Hansen solubility parameter of 13.0 J / cc １／２ ~15.5J / cc １／２ 2. The composition of claim 1 ,

6. The polar Hansen solubility parameter of the at least one glycol ether is 0.5 J / cc or less. １／２ ~3.0 J / cc １／２ 2. The composition of claim 1 ,

7. The at least one glycol ether has a hydrogen bond Hansen solubility parameter of 6.5 J / cc. １／２ ~8.5J / cc １／２ 2. The composition of claim 1 ,

8. 10. The composition of claim 1, wherein the composition comprises from 20% to 70% by weight of the at least one glycol ether, from 1% to 15% by weight of the at least one organic amine, from 0.01% to 10% by weight of the at least one surfactant, and the balance water, each based on the total weight of the composition.

9. 1. A process for preparing a glycol ether-containing water-based composition comprising: (a) at least one glycol ether having a boiling point greater than 240° C. and a VOC content in terms of vapor pressure less than 10 Pa at 20° C.; (b) at least one organic amine; (c) at least one surfactant; (d) water to form said water-based composition.

10. 10. The process of claim 9, wherein the composition is used as a cleaning formulation for cleaning printed circuit boards during their manufacture.

11. 1. A process for cleaning a substrate, comprising: (A) providing a substrate to be cleaned, the substrate having a first amount of contaminant deposited thereon; (B) contacting the substrate of step (A) with the aqueous composition of claim 1 for a period of time, wherein after the contacting step (B), the first amount of contaminants on the substrate is reduced to a second reduced amount of contaminants to form a cleaned substrate, the second reduced amount of contaminants on the cleaned substrate of step (B) covering less than 0.01 percent of a surface area of ​​the substrate and less than the first amount of contaminants on the substrate of step (A); (C) optionally rinsing the cleaned substrate from step (B) with clean or pure water.

12. 12. The process of claim 11, wherein the time of the contacting step (B) to remove contaminants from the substrate is less than 120 seconds under ultrasonic cleaning conditions (90 Hz) at 45°C.

13. 12. The process of claim 11, wherein the duration of said contacting step (B) is less than 120 seconds at 25°C.

14. The process of claim 11 , wherein the substrate is a printed circuit board.

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