JPH06293899A - Cleaning agent for flux removal - Google Patents

Abstract

PURPOSE:To obtain the subject cleaning agent having excellent environmental conservation, low toxicity, high safety and excellent handleability, comprising an alpha-hydroxyisobutyric acid alkyl ester and an organic carboxylic acid as active ingredients. CONSTITUTION:This cleaning agent comprises 85-99.5wt.% of an alpha- hydroxyisobutyric acid alkyl ester (preferably alpha-hydroxyisobutyric acid methyl ester or alpha-hydroxyisobutyric ethyl ester) and 0.5-15wt.% of an organic carboxylic acid (preferably alpha-hydroxyisobutyric acid, lactic acid or glycolic acid) or optionally contains 5-50wt.% of a hydrophilic organic solvent (e.g. methanol or ethanol). In order to improve cleaning power, if necessary, a surfactant may combinedly be used as active ingredients.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cleaning agent for flux removal, and more particularly, to enhance the bonding force between solder and parts when soldering electric or electronic circuit parts or precision machine parts. The applied flux,
The present invention relates to a flux removing cleaning agent suitable for cleaning and removing from a component after soldering. The flux cleaning process after soldering is used in many situations such as printed circuit manufacturing, printed wiring board manufacturing, and precision machine parts assembly.

[0002]

2. Description of the Related Art Conventionally, in order to firmly bond the solder and the base material in a printed circuit or printed wiring board manufacturing process in the electric and electronic industries, an assembly process in the precision machinery industry, etc. Flux is applied to the surface of the base material. The flux removes the oxide film covering the surface of the solder and the base material to improve the wettability of both, and it can be said that the quality of the solder joint largely depends on the performance of the flux. However, the flux usually has some corrosiveness, as is clear from its function. Therefore, if flux residue remains on the surface of the base material even after soldering, that part will gradually be corroded, and
In the case of electronic parts, it causes poor conductivity, and in precision machine parts, it causes strength deterioration and failure. Therefore, the product with the flux residue attached does not become a product, and solvent cleaning is usually performed to remove the flux residue in the finishing process of such parts.

Conventionally, as a cleaning agent for removing flux residue after soldering, that is, a cleaning agent for flux removal, CFC 113 (1, 1, 2-trichloro-1, 2,
2-trifluoroethane), methyl chloroform (1,
1,1-trichloroethane) and trichloroethylene are mainly used as halogen-based solvents. In particular, CFC 113 has been widely used because it is nonflammable, has low toxicity, is excellent in stability, and has the property of selectively dissolving various stains without damaging the base material such as metal, plastic, and elastomer. . However, Freon 1
13 and methylchloroform are depleting the ozone layer in the stratosphere, which in turn causes the development of skin cancers, and their use is being rapidly restricted. Also,
Trichlorethylene is being carcinogenic, and its use is being restricted from the viewpoint of safety.

Therefore, an alternative CFC-based cleaning agent having a cleaning property that can replace CFC 113 and free from the concern of ozone layer depletion is being actively developed. For example, 1,2-
Difluoroethane as a main component (Japanese Patent Laid-Open No. 1-13
No. 2694), a mixture of 1,1-dichloro-2,2,2-trifluoroethane and dimethoxymethane (JP-A-2-178396) and hexafluorobenzene as a main component (JP-A-3-167298). Many alternative CFCs have been proposed. But,
These solvents do not reach CFC 113 in terms of performance,
In the future, these halogen-based solvents will not be an essential solution because they will be completely regulated for use due to environmental and safety issues.

[0005]

As described above, in the technical field of the present invention, a non-halogen solvent is the main component, no environmentally destructive substances are released into the atmosphere and water, and toxicity and safety such as carcinogenicity are ensured. The development of a flux-removing cleaning agent that has a high dissolving power and is capable of completely removing flux residues without damaging the base material without any of the above problems has become an important issue.

The present invention overcomes the drawbacks of the conventional cleaning agents for flux removal as described above, is composed of a non-halogen solvent, has a high cleaning and removing ability, does not produce environmentally destructive substances, and is toxic and unpleasant. The purpose of the present invention is to provide a safe flux-removing cleaner having no odor and having a relatively high boiling point.

[0007]

DISCLOSURE OF THE INVENTION As a result of intensive studies to develop a flux detergent having the above-mentioned preferable properties, the present inventors have found that a mixture containing α-hydroxyisobutyric acid alkyl esters and an organic carboxylic acid. Has reached the present invention.

That is, the present invention relates to a cleaning agent for flux removal, which comprises an alkyl ester of α-hydroxyisobutyric acid and an organic carboxylic acid as active ingredients.

The present invention will be described in detail below. It is an essential condition that the detergent according to the present invention contains α-hydroxyisobutyric acid alkyl ester and an organic carboxylic acid as active ingredients.

Examples of the α-hydroxyisobutyric acid alkyl ester used in the present invention include methyl α-hydroxyisobutyrate, ethyl α-hydroxyisobutyrate, isopropyl α-hydroxyisobutyrate, and butyl α-hydroxyisobutyrate. In particular, methyl α-hydroxyisobutyrate or ethyl α-hydroxyisobutyrate is preferable from the viewpoint of detergency. These α-hydroxyisobutyric acid alkyl esters may be used alone or in combination of two or more kinds.

The concentration of the alkyl ester of α-hydroxyisobutyric acid is preferably in the range of 50 to 99.9% by weight. The range is more preferably 85 to 99.5% by weight. If the concentration of the α-hydroxyisobutyric acid alkyl ester is less than 50%, the features of the present invention, such as cleanability, safety and operability, may be impaired.

As the organic carboxylic acid used in the present invention,
It is soluble in a solution system containing α-hydroxyisobutyric acid alkyl ester as the main ingredient. And the like, and polycarboxylic acids such as oxalic acid or succinic acid are preferred. The combined use of these organic carboxylic acids significantly improves the cleaning power for the flux. The concentration of the organic carboxylic acid is preferably in the range of 0.1 to 50% by weight. More preferably 0.5 to 15
It is in the range of% by weight.

If any one of the active ingredients in the present invention is lacking, the detergency will be poor. The cleaning agent of the present invention can be further added with a hydrophilic organic solvent, water or the like, whereby the cleaning property, operability and safety can be improved.

Examples of the hydrophilic organic solvent used in combination include methanol, ethanol, isopropanol, pyrrolidone, N-methylpyrrolidone, dimethylformamide, dimethylacetamide, methyl acetate, ethyl acetate,
Methyl lactate, ethyl lactate, butyl glycolate, methyl α-methoxyisobutyrate, methyl β-methoxyisobutyrate,
Examples thereof include nitromethane, nitroethane, acetonitrile, γ-butyrolactone, dimethyl sulfoxide or sulfolane. Two or more kinds of these hydrophilic organic solvents and water can be used in combination. The concentration is preferably in the range of 5 to 50% by weight. Further, in order to improve the detergency and the like, surfactants may be used in combination, if necessary.

The solder and the flux to which the cleaning agent of the present invention is applied are not particularly limited and can be arbitrarily selected from those usually used.

[0016]

EXAMPLES The present invention will be specifically described below with reference to examples and comparative examples, but the present invention is not limited to the following examples.

Examples 1 to 11 Commercially available flux [Tamura F-A1-4, manufactured by Tamura Manufacturing Co., Ltd.] was uniformly applied to the entire surface of a printed circuit board (copper clad laminate), and then predried at 100 ° C. 220 ° C
The product baked in step 2 was used as the object to be washed. The cleaning test was carried out in the cleaning agent of the present invention shown in Table 1 for the substrate to be cleaned.
After dipping and shaking at 0 ° C. for 1 minute, washing with water and drying were performed, and the residual adhesion amount on the surface of the article to be washed was measured to evaluate the detergency.

Comparative Examples 1 and 2 For comparison, a cleaning test was conducted according to the method of the above-described example except that Freon 113 or methyl lactate was used as the flux cleaning agent.

The results of the above Examples and Comparative Examples are shown in Table 1. The residual adhesion amount was measured visually and with a metallurgical microscope. ◯: No residue visually or by a metallurgical microscope. Δ: There is no residue visually, but there is a metallurgical microscope. X: There is a residue visually.

[0020]

[0021]

The cleaning agent for flux removal of the present invention is extremely excellent in cleanability, has no problems in environmental protection, and has high safety. Further, the present invention has the following advantages. (1) Solubility in flux is extremely high, and cleaning and removability are excellent. (2) No environmentally harmful substances are released into the air or water. (3) It is biodegradable and does not accumulate in nature. (4) It has low toxicity and is not carcinogenic. (5) Boiling point and flash point are relatively high, and operability and safety are significantly improved. (6) It is water-soluble and can be used in an aqueous system. (7) Does not attack the base material.

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Claims (4)

[Claims] 1. A detergent for flux removal, which comprises an alkyl ester of α-hydroxyisobutyric acid and an organic carboxylic acid as active ingredients. 2. The cleaning agent is water, methanol, ethanol, isopropanol, pyrrolidone, N-methylpyrrolidone, dimethylformamide, dimethylacetamide,
Methyl acetate, ethyl acetate, methyl lactate, ethyl lactate, butyl glycolate, α-methoxyisobutyrate, β-
The cleaning agent according to claim 1, which contains at least one selected from methyl methoxyisobutyrate, nitromethane, nitroethane, acetonitrile, γ-butyrolactone, dimethyl sulfoxide and sulfolane. 3. An α-hydroxyisobutyric acid alkyl ester is at least one selected from methyl α-hydroxyisobutyrate, ethyl α-hydroxyisobutyrate, isopropyl α-hydroxyisobutyrate and butyl α-hydroxyisobutyrate. The cleaning agent according to claim 1, which is 4. The organic carboxylic acid is at least one selected from α-hydroxyisobutyric acid, lactic acid, glycolic acid, malic acid, tartaric acid, citric acid, oxalic acid and succinic acid. Washing soap.