KR102419315B1 - A cleaning composition for a lead-free soldering solvent, a cleaning method for a lead-free soldering solvent - Google Patents

Abstract

(n은 1 내지 3의 정수, R은 탄소수 1 내지 4의 알킬기 또는 히드록시 알킬기를 나타냄)[Problem] The present invention can clean solvent residues generated when soldering rosin flux or water-soluble solvent in a short time, and when the object to be cleaned is a mounted substrate having a complex and fine structure, etc. Its main object is to provide a cleaning composition for lead-free soldering solvents having excellent crevice cleaning properties.
[Solutions] An organic solvent (A) containing at least one selected from the group consisting of diethylene glycol ethyl methyl ether, diethylene glycol diethyl ether and dipropylene glycol dimethyl ether, an alkali represented by the following formula (1) A cleaning composition for a lead-free soldering solvent comprising nolamine (B) and hydroxycarboxylic acid (C).
[Formula 5]

(n is an integer of 1 to 3, R represents an alkyl group having 1 to 4 carbon atoms or a hydroxyalkyl group)

Description

A cleaning composition for a lead-free soldering solvent, a cleaning method for a lead-free soldering solvent

The present invention relates to a cleaning composition for a lead-free solder flux and a method for cleaning a lead-free solder flux.

Soldering is commonly performed when surface mounting electronic components on printed wiring boards. In general, during soldering, a solvent is used for the purpose of removing the oxide film on the surface of the solder and the base material, preventing re-oxidation of the soldering and the surface of the base material, and obtaining sufficient solderability. However, solvents are corrosive, and solvent residues degrade the quality of printed wiring boards. Therefore, solvent residue may be removed by washing|cleaning.

Conventionally, a rosin-based solvent (rosin solvent) has been widely used for solder bonding of surface mount components, and the rosin solvent residue is washed with a halogenated hydrocarbon such as Freon. However, since the use of halogenated hydrocarbons has been regulated from the fact that they are very harmful to the environment, various substances to replace halogenated hydrocarbons and the like have been studied as cleaning agents for rosin solvent residues. For example, a cleaning agent containing a non-halogenated organic solvent such as a polyoxyalkylene alkyl ether-based organic solvent has been proposed as one with a small risk of ignition and environmental impact, and excellent dissolving power of rosin solvent residues. There is (Patent Documents 1 to 3).

In addition, washing with water instead of halogenated hydrocarbons is being considered as one of measures against environmental problems. A solvent that can be washed with water is not a hydrophobic solvent like a rosin solvent, but a water-soluble solvent in which an activator, a solvent, etc. are added to a polyether-based resin or the like. Since the water-soluble solvent residue has hygroscopicity, cleaning is essential. This is distinct from rosin solvent residues, which do not require cleaning. Therefore, water-soluble solvent residues are generally washed with water, but washing may not be sufficient in some cases.

Therefore, it is conceivable to use the detergents of the said patent documents 1 - 3 etc. as a detergent of the water-soluble solvent residue. However, these detergents are not considered for the purpose of removing the water-soluble solvent residue, and since the water-soluble solvent residue has different characteristics from the rosin solvent residue, it is difficult to sufficiently clean the water-soluble solvent residue using the above-mentioned rosin solvent detergent. It was difficult. Moreover, although the cleaning composition of patent document 3 contains the alkanolamine which has an alkyl group, this amine also has the problem of corrosion of metal substrates, such as a copper plate.

[Patent Document 1] Japanese Patent Laid-Open No. 4-57899 [Patent Document 2] Japanese Patent Laid-Open No. 8-73893 [Patent Document 3] Japanese International Publication No. 2009/020199 Specification

The present invention is a lead-free soldering solvent cleaner that can clean solvent residues generated when soldering rosin solvent or water-soluble solvent in a short time, and has excellent crevice cleaning properties even when the object to be cleaned is a mounting board having a complex and fine structure. The main object is to provide a composition.

As a result of intensive examination, the present inventors found that a cleaning composition containing hydroxy carboxylic acid in an organic solvent and amine containing a specific glycol ether solves the above problems and came to complete the present invention. That is, the present invention relates to the following cleaning composition for a lead-free soldering solvent and a cleaning method for a lead-free soldering solvent.

1. At least one selected from the group consisting of diethylene glycol ethyl methyl ether, diethylene glycol diethyl ether, and dipropylene glycol dimethyl ether; Lead-free solder containing an organic solvent (A) containing an alkanolamine (B) represented by the following formula (1), and hydroxy carboxylic acid (C) A cleaning composition for a solder flux.

[Formula 2]

(n is an integer of 1 to 3, R represents an alkyl group having 1 to 4 carbon atoms or a hydroxyalkyl group)

2. For the lead-free soldering solvent of 1 above, in which (B) component is N,N-bis(2-hydroxyethyl)-N-cyclohexylamine (N,N-bis(2-hydroxyethyl)-N-cyclohexylamine) detergent composition.

3. The lead-free soldering solvent of 1 or 2 above, wherein the component (C) is at least one selected from the group consisting of citric acid, isocitric acid, tartaric acid and malic acid. cleaning composition for use.

4. (A) component 2.8 to 70% by weight, component (B) 0.04 to 5% by weight, (C) component 0.01 to 2% by weight, and water 5 to 97% by weight, of 1 to 3 above Any one of the lead-free soldering solvent cleaning composition.

5. The cleaning composition for a lead-free soldering solvent according to any one of 1 to 4 above, wherein the surface tension at a temperature of 25°C is 10 to 60 dyne/cm.

6. A cleaning method for a lead-free soldering solvent, comprising the step of cleaning the cleaning composition for a lead-free soldering solvent according to any one of 1 to 5 above by contacting the cleaning object to be cleaned with a lead-free soldering solvent attached thereto.

According to the cleaning composition for lead-free soldering solvent of the present invention (hereinafter also referred to as cleaning composition), the solvent residue generated when soldering rosin solvent or water-soluble solvent can be cleaned in a short time, and the object to be cleaned has a complicated and fine structure It has excellent crevice cleaning properties even in the case of a mounted board with In addition, the cleaning composition has an effect of not corroding the metal substrate.

[FIG. 1] When "no solvent residue" in the crevice cleaning property, that is, the figure is "double-circle".
[FIG. 2] When "solvent residue is present" in crevice cleaning property, that is, a figure of "x".

"Lead-free soldering solvent", which is the cleaning object of the cleaning composition of the present invention, specifically means a solvent residue containing tin derived from lead-free soldering, for example, (A) lead-free soldering and solvent composition in powder form and (B) solvent residues generated after soldering an electrode formed by lead-free soldering through a solvent composition.

In addition, as "lead-free soldering", Sn-Ag type soldering, Sn-Cu type soldering, Sn-Ag-Cu type soldering, Sn-Zn type soldering, Sn-Sb type soldering, etc. are mentioned, for example.

In addition, as a "solvent composition", specifically, for example, base resins such as resin acids (natural rosin, polymerized rosin, α, β unsaturated carboxylic acid-modified rosin, etc.) and synthetic resins (acrylic resin, polyamide resin, etc.); Activators (organic acids such as adipic acid, halogen compounds such as diethylamine hydrogen bromide silver, etc.), thixotropic agents (hydrogenated castor oil, hydroxystearate ethylene bisamide, etc.), solvents (diethylene glycol monohexyl, etc.) ether, diethylene glycol monobutyl ether, etc.) as a main component.

The cleaning composition of the present invention is an organic solvent (A) containing at least one selected from the group consisting of diethylene glycol ethyl methyl ether, diethylene glycol diethyl ether, and dipropylene glycol dimethyl ether (hereinafter referred to as (A) component ), an amine (B) represented by the following formula (1) (hereinafter referred to as (B) component) and hydroxycarboxylic acid (C) (hereinafter referred to as (C) component).

[Formula 3]

(n is an integer of 1 to 3, R represents an alkyl group having 1 to 4 carbon atoms or a hydroxyalkyl group)

(A) As a component, at least 1 sort(s) selected from the group which consists of diethylene glycol ethyl methyl ether, diethylene glycol diethyl ether, and dipropylene glycol dimethyl ether is included. Since such dialkyl dialkylene glycol has low surface tension and viscosity, it tends to easily enter the gap of the substrate.

In addition, as (A) component, other glycol ether can be used together, unless crevice cleaning property is impaired. Other glycol ethers are not particularly limited, but include, for example, diethylene glycol monomethyl ether, diethylene glycol dimethyl ether, diethylene glycol monoethyl ether, diethylene glycol monon-propyl ether, diethylene glycol din-propyl ether, diethylene glycol methyl propyl ether, diethylene glycol ethyl propyl ether, diethylene glycol monon-butyl ether, diethylene glycol din-dibutyl ether, diethylene glycol methyl butyl ether, diethylene glycol ethyl butyl ether, diethylene glycol Ethylene glycol propyl butyl ether, diethylene glycol monon-pentyl ether, diethylene glycol din-pentyl ether, diethylene glycol methyl pentyl ether, diethylene glycol ethyl pentyl ether, diethylene glycol propyl pentyl ether, diethylene glycol butyl pentyl ether diethylene glycol ethers such as ether and ethylene glycol monon-hexyl ether; dipropylene glycol monomethyl ether, tri or tetra ethylene glycol ether corresponding thereto, and the like, and these may be used alone or in combination of two or more, and the content is not particularly limited, but the detergent of the present invention With the composition being 100% by weight, 40% by weight or less is preferred.

The content of component (A) is not particularly limited, but in terms of crevice cleaning properties, generally 100% by weight of the cleaning composition of the present invention, 2.8 to 70% by weight, preferably 5 to 70% by weight, more preferably 20 to 70% by weight.

(B) Component is an alkanolamine represented by the following formula (1), does not corrode a metal substrate, and is a necessary component in order to exhibit the cleaning property of a solvent.

[Formula 4]

(n is an integer of 1 to 3, R represents an alkyl group having 1 to 4 carbon atoms or a hydroxyalkyl group)

As the alkanolamine represented by the formula (1), for example, N-hydroxyethyl N-methyl N-cyclohexylamine (N-hydroxyethyl N-methyl N-cyclohexylamine), N-ethyl N- (2 -Hydroxyethyl)-N-cyclohexylamine (N-ethyl N-(2-hydroxyethyl)-N-cyclohexylamine), N,N-bis(2-hydroxymethyl)-N-cyclohexylamine (N,N -bis(2-hydroxymethyl)-N-cyclohexylamine), N,N-bis(2-hydroxyethyl)-N-cyclohexylamine (N,N-bis(2-hydroxyethyl)-N-cyclohexylamine), etc. can These can be used individually or in combination of 2 or more types. Among them, N,N-bis(2-hydroxyethyl)-N-cyclohexylamine is preferable from the viewpoint of crevice cleaning properties.

(B) The content of the component is not particularly limited, but in terms of crevice cleaning properties, generally 0.04 to 5% by weight, preferably 0.04 to 3% by weight, more preferably 0.1 based on 100% by weight of the cleaning composition of the present invention to 2% by weight.

The cleaning composition of this invention is an alkanolamine (B-1) (henceforth (B-1) component) other than (B) component, or an aliphatic amine (B-2) (henceforth (B-2) component) ) and the like may be used in combination. (B-1) Although it does not specifically limit as a component, For example, diethanolamine, N-methyl diethanolamine, N-ethyl diethanolamine, N-n-butyl diethanolamine, N-t- butyl diethanolamine, triethanol amine, N-(β-aminoethyl)ethanolamine, N-(β-aminoethyl)isopropanolamine, and the like. In addition, although it does not specifically limit as a component (B-2), For example, Primary aliphatic amines, such as octylamine, decylamine, dodecylamine, tetradecylamine, hexadecylamine, 2-ethylhexylamine; N,N,N',N'-tetramethyl pentamethylene diamine, N,N, N',N'-tetraethyl pentamethylene diamine, N,N,N',N'-tetraisopropyl pentamethylene diamine, N ,N,N',N'-tetra-n-propyl pentamethylene diamine, N,N,N',N'-tetramethyl hexamethylene diamine, N,N,N',N'-tetraethyl hexamethylene diamine, tertiary diamines such as N,N,N',N'-tetra isohexamethylene diamine and N,N,N',N'-tetra-n-propyl hexamethylene diamine; Diaminoalkyl such as bis(2-dimethyl aminoethyl)ether, bis(2-ethyl aminoethyl)ether, bis(2-diisopropyl aminoethyl)ether, bis(2-di-n-propyl aminoethyl)ether ether; 1,1,7,7-tetramethyl diethylene triamine, 1,1,7,7-tetraethyl diethylene triamine, 1,1,7,7-tetraisopropyl diethylene triamine, 1,1, 7,7-tetra-n-propyl diethylene triamine, N,N,N',N'',N''-pentamethyl diethylene triamine, 4-methyl-1,1,7,7-tetraethyl Triamines such as diethylene triamine, 4-methyl-1,1,7,7-tetraisopropyl diethylene triamine, 4-methyl-1,1,7,7-tetra-n-propyl diethylene triamine and the like. These can be used individually or in combination of 2 or more types. Although it does not specifically limit as content of (B-1) component and (B-2) component, From a viewpoint of not corroding a metal substrate, the cleaning composition of this invention shall be 100 weight%, and it shall be 2 weight% or less. it is preferable

(C) The component is not particularly limited, and various known ones can be used, for example, citric acid, isocitric acid, malic acid, tartaric acid, etc. can A salt of the above acid may be used, and examples of the salt include sodium salt, potassium salt, ammonium salt, and alkanolamine salt. These can be used individually or in combination of 2 or more types. Among these, at least 1 sort(s) selected from the group which consists of citric acid, isocitric acid, and malic acid from a viewpoint of solvent residue cleaning property is preferable, and citric acid is more preferable.

(C) The content of the component is not particularly limited, but from the viewpoint of solvent residual solubility, generally 0.01 to 2% by weight, preferably 0.1 to 2% by weight, more preferably 100% by weight of the cleaning composition of the present invention preferably 0.1 to 1% by weight.

The cleaning composition of the present invention also contains water. As water, pure water, ion-exchange water, purified water, etc. are mentioned, for example. In addition, about mixing of water, you may divide into one time or multiple times. The content of water is also not particularly limited, but from the standpoint of the non-hazardous nature of the detergent, in general, the detergent composition of the present invention is 100% by weight, 5 to 97% by weight, preferably 20 to 90% by weight, more preferably 20 to 50% by weight.

In addition, the cleaning composition of the present invention may contain a non-halogen-based organic solvent if necessary, for example, 1,3-dimethyl-2-imidazolidinone (imidazolidinone), 1,3-diethyl-2 -solvents containing a nitrogen atom, such as imidazolidinone, 1,3-dipropyl-2-imidazolidinone, and N-methyl-2-pyrrolidone; hydrocarbons such as hexane, heptane and octane; alcohols such as methanol, ethanol, and benzyl alcohol; ketones such as acetone and methyl ethyl ketone; ethers such as diethyl ether, tetrahydrofuran and glycol ether; Ester, such as ethyl acetate and methyl acetate, etc. are mentioned, These can be used individually or in combination of 2 or more types.

In addition, the cleaning composition of the present invention is a range that does not impair the intended effect of the present invention, various known additives, for example, nonionic surfactants (except those corresponding to component (A)), anionic surfactants, cationic Various surfactants, such as surfactant, etc. can be added.

As the nonionic surfactant, for example, the general formula (2): R ² -O-(CH ₂ -CH ₂ -O)eH (wherein R ² is an alkyl group having 8 to 20 carbon atoms, e is 0 to 20) or an ethylene oxide adduct of fatty acid amides, sorbitan fatty acid esters, sucrose fatty acid esters, fatty acid alkanol amides, and corresponding polyoxypropylene surfactants, etc.; These can be used individually or in combination of 2 or more types.

Examples of the anionic surfactant include sulfuric acid ester-based anionic surfactants (sulfuric acid ester salts of higher alcohols, alkylsulfuric acid ester salts, polyoxyethylene alkylsulfuric acid ester salts, etc.), sulfonate-based anionic surfactants (alkyl sulfonic acid salts, alkyl benzene sulfonic acid salts, etc.), and these may be used alone or in combination of two or more.

As a cationic surfactant, an alkylated ammonium salt, a quaternary ammonium salt, etc. are mentioned, for example, These can be used individually or in combination of 2 or more types.

Examples of the amphoteric surfactant include amino acid type and betaine type amphoteric surfactant, and these may be used alone or in combination of two or more.

The detergent composition of this invention can mix|blend various well-known additives. Although it does not specifically limit as an additive, For example, a chelating agent, antioxidant, a redox agent, a scale inhibitor, a rust-preventive agent, a pH adjuster, an antifoaming agent, etc. are mentioned.

The physical properties of the cleaning composition of the present invention are not particularly limited, but for example, the surface tension is usually about 10 to 60 dyne/cm at a temperature of 25° C., preferably about 10 to 50 dyne/cm, more preferably is 10 to 40 dyne/cm. Since the surface tension is in the said range, the clearance gap cleaning property tends to become favorable.

In addition, the cleaning composition of the present invention does not have a flash point and is a non-hazardous material.

Moreover, the cleaning composition of this invention can contain non-halogen type organic solvent other than the said (A) component as needed. For example, nitrogen-containing compound solvents (1,3-dimethyl-2-imidazolidinone, 1,3-diethyl-2-imidazolidinone, 1,3-dipropyl-2-imidazolidinone, N-methyl-2-pyrrolidone, etc.), hydrocarbon solvents (hexane, heptane, octane, etc.), alcohol solvents (methanol, ethanol, benzyl alcohol, etc.), ketone solvents (acetone, methyl ethyl ketone, etc.), ether solvents (diethyl ether, tetrahydrofuran, glycol ethers, etc.) and ester solvents (ethyl acetate, methyl acetate, etc.), and these may be used alone or in combination of two or more.

<How to remove lead-free soldering solvent>

The removal method of the lead-free brazing solvent of this invention can remove the said solvent by making the cleaning composition of this invention contact the to-be-cleaned object to which the lead-free brazing solvent adhered.

The use form of the cleaning composition of this invention is not specifically limited, Various well-known methods are employable. For example, a method in which a cleaning agent composition is sprayed onto an object to be cleaned with a lead-free soldering solvent attached thereto using a spray device (refer to Japanese Patent Laid-Open No. 2007-096127), ultrasonic cleaning by immersing the object to be cleaned in a cleaning agent composition method, and a method using a direct-flow washing machine (Japanese registered trademark "Direct Pass", manufactured by Arakawa Chemical Industry Co., Ltd., Japanese Patent No. 2621800, etc.).

After removing the lead-free soldering solvent using the cleaning composition of the present invention, the obtained cleaning product is preferably rinsed with water. In particular, as the removal method of the present invention, a method of spraying water on the cleaned object after obtaining a cleaning product by spraying spraying the cleaning composition of the present invention onto a lead-free brazing solvent is preferable.

In addition, the rinsing treatment can be repeated a plurality of times. For example, the cleaning composition adhering to the surface of the cleaning object can be effectively removed by performing a final rinse treatment after pre-rinsing the cleaning material.

The pre-rinsing treatment may be performed according to an existing pre-rinsing treatment method using pure water or the like.

The final rinsing treatment may be performed according to a conventional method. For example, the method of processing using pure water etc. as a pre-rinsing process material is mentioned.

After the pre-rinsing treatment and/or after the final rinsing treatment, a drying treatment may be performed as needed.

In addition, when the rinsing process is performed by spraying water onto the object to be cleaned, it is preferable that the cleaning composition of the present invention does not contain the above-mentioned various surfactants from the viewpoint of low foaming property.

[Example]

Hereinafter, the present invention will be described in detail through Examples and Comparative Examples, but it goes without saying that the scope of the present invention is not limited thereto.

(Preparation of cleaning composition for lead-free soldering solvent)

Each component shown in Table 1 was mixed (based on weight %) to prepare a cleaning composition for a lead-free soldering solvent of Examples 1 to 10 and Comparative Examples 1 to 6.

[Corrosion of metal substrate (check for discoloration)]

In a 200 ml beaker, 150 g of the cleaning composition for lead-free soldering solvent of Example 1 was taken, and an aluminum plate (aluminum plate A1050P (as defined in JIS H3100), dimensions: 70 mm × 150 mm × 0.8 mm) was placed at 60°C. It was immersed for 10 minutes. After cooling, the aluminum plate was taken out and washed well with water, and droplets were removed by a nitrogen blow. The presence or absence of discoloration of the aluminum plate was visually confirmed. In addition, the cleaning compositions for lead-free soldering solvents of Examples 2 to 10 and Comparative Examples 1 to 6 were evaluated in the same manner. The results are shown in Table 1 (the same hereinafter).

(Evaluation standard)

○: There is no discoloration of the aluminum plate. x: There is discoloration of the aluminum plate.

[Production of water-soluble solvent residue]

30 parts by weight of a commercially available water-soluble solvent (product name 'WF-6317', manufactured by Senjyu Metal Industry Co., Ltd.) and lead-free solder powder (96.5Sn3.0Ag0.5Cu, 20-38 μm, manufactured by Mitsui Mining & Smelting) 70 A solder paste was prepared by mixing parts by weight. The solder paste was put into an ointment can and melted by heating on a hot plate at a temperature of 270°C, then cooled and the water-soluble solvent residue separated from the solder paste was collected. The solvent residue was used as a model of the residue generated after soldering with lead-free water-soluble solder.

A part of the solvent residue was collected, and the tin concentration was measured using a wavelength-dispersive fluorescence X-ray analyzer (product name "ZSX100e", manufactured by Rigaku Corporation). As a result, 5% by weight of tin was detected.

[Production of model board for cleaning]

On a base glass epoxy substrate (40 cm long × 40 cm wide × 1 mm thick), a few resist bumps with a height of 30 μm are formed to form a glass platelet (16 cm long × 16 cm wide × 0.5 mm thick) to become a spacer. ) was adhered on one sheet to form a substrate for cleaning gaps. Thereafter, 10 µl of a solution obtained by diluting the water-soluble solvent residue with methanol to a concentration of 15% was supplied to the grooves between the glass platelets to prepare a model substrate for cleaning.

[Creep cleaning property]

The model board|substrate was spray-cleaned (pressure 0.2 MPa, temperature 50 degreeC, 1 minute) with the cleaning composition for lead-free soldering solvent of Example 1 (liquid temperature 50 degreeC). The substrate was rinsed by spray cleaning with water (pressure 0.2 MPa, 1 min), and after removing the droplets by nitrogen blow, it was dried in a tail wind dryer at 80° C. for 10 min. The solvent residue remaining on the substrate after drying was observed with an optical microscope (manufactured by Keyence Co., Ltd., VHX6000). The evaluation criteria are as follows. In addition, the cleaning compositions for lead-free soldering solvents of Examples 2 to 10 and Comparative Examples 1 to 6 were also evaluated.

(Evaluation standard)

◎: no solvent residue (refer to FIG. 1)

○: There is a little solvent residue, but the level does not affect the electrical reliability of the board

△: There is a small amount of solvent residue, and the level slightly affects the electrical reliability of the substrate

×: there is a solvent residue (refer to FIG. 2)

※ The content of each component is expressed as a weight ratio (% by weight).

The abbreviations in Table 1 indicate the following compounds.

DEDG: Diethylene glycol diethyl ether

MEDG: Diethylene glycol ethyl methyl ether

DPDM: Dipropylene glycol dimethyl ether

BDG: Diethylene glycol monon-butyl ether

CHE-20: N,N-bis(2-hydroxyethyl)-N-cyclohexylamine (trade name: "amino alcohol CHE-20", manufactured by Nippon Emulsifier Co., Ltd.)

MBD: N-n-butyl diethanolamine

[Cleaning gap between model boards supplied with rosin solvent residue]

A model board was manufactured in the same manner as in [0055] to [0057] using a commercially available solder paste containing a rosin-based solvent (product name "Fine Solder VAPY-LF219", manufactured by Arakawa Chemical Industry Co., Ltd.) (As this product is a solder paste, the adjustment process of the solder paste is omitted). As a result of cleaning the model board|substrate with the cleaning agent composition for lead-free soldering solvent of Example 4, it was confirmed that similarly excellent crevice cleaning properties were exhibited.

Claims (6)

Containing at least one selected from the group consisting of diethylene glycol ethyl methyl ether, diethylene glycol diethyl ether, and dipropylene glycol dimethyl ether A lead-free solder flux containing an organic solvent (A), an alkanolamine (B) represented by the following Chemical Formula 1, and a hydroxy carboxylic acid (C) ) for a cleaning composition.
[Formula 1]

(n is an integer of 1 to 3, R represents an alkyl group having 1 to 4 carbon atoms or a hydroxyalkyl group)
The lead-free soldering flux according to claim 1, wherein component (B) is N,N-bis(2-hydroxyethyl)-N-cyclohexylamine (N,N-bis(2-hydroxyethyl)-N-cyclohexylamine). cleaning composition for use.
The method according to claim 1 or 2, wherein the component (C) is at least one selected from the group consisting of citric acid, isocitric acid, tartaric acid and malic acid, A cleaning composition for a lead-free soldering solvent.
3. The component according to claim 1 or 2, wherein the component (A) contains 2.8 to 70% by weight, the component (B) contains 0.04 to 5% by weight, the component (C) contains 0.01 to 2% by weight, and water contains 5 to 97% by weight. The cleaning composition for lead-free soldering solvents to contain.
The cleaning composition for a lead-free soldering solvent according to claim 1 or 2, wherein the surface tension at a temperature of 25°C is 10 to 60 dyne/cm.
A cleaning method for a lead-free soldering solvent, comprising the step of cleaning the cleaning composition for a lead-free soldering solvent according to claim 1 or 2 by contacting the cleaning agent to be cleaned with a lead-free soldering solvent attached thereto.

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