JPH07195044A - Cleaning method - Google Patents

Abstract

(57) [Summary] [Structure] In a cleaning method for cleaning electronic parts or precision parts with a cleaning agent, the active ingredient such as a nonionic surfactant is separated from the active ingredient by a certain amount or more at a certain temperature. There is a step of washing with a water dilution liquid of the cleaning agent at a temperature of 20 to 100 ° C. without phase separation, and a step of separating organic substances in the washing liquid while keeping the washing liquid after washing at 20 ° C. or higher. A method for cleaning electronic parts or precision parts characterized by the above. [Effects] According to the present invention, the organic substances in the cleaning liquid after cleaning can be efficiently separated and removed to a high concentration, and the subsequent wastewater treatment process can be simplified. Therefore, fats, machine oils, cutting oils, greases, etc. It is possible to industrially advantageously clean electronic parts or precision parts on which dirt such as wax, liquid crystal, or flux adheres.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to electronic parts, precision parts, and jigs and tools used for assembling and processing oils, machine oils, cutting oils, greases, waxes, liquid crystals, fluxes and other contaminants. And the like (hereinafter referred to as electronic parts or precision parts), and more particularly, to a cleaning method excellent in processability of a cleaning liquid after cleaning in the cleaning process and maintenance of the cleaning property in the cleaning process.

[0002]

2. Description of the Related Art Conventionally, the problems to be solved by the invention
Hydrocarbons such as kerosene, benzene, xylene, etc. are used for removing dirt mainly composed of organic substances such as oils, machinery oils, cutting oils, greases, waxes, liquid crystals and fluxes existing on solid surfaces such as precision parts and jigs and tools. Solvents: Chlorine-based solvents such as trichlorethylene and tetrachloroethylene; Freon-based solvents such as trichlorotrifluoroethane; water-based detergents containing surfactants and builders are used. In particular, for electronic, electrical, mechanical and other parts, chlorofluorocarbon-based solvents or chlorine-based solvents have been used by taking advantage of their high cleaning properties and flame retardancy.

However, detergents using freon-based and chlorine-based solvents have major problems in safety, toxicity and environmental pollution. In addition, hydrocarbon solvents, especially benzene, xylene, etc., are highly toxic and are compounds designated as hazardous substances under the Industrial Safety and Health Act. Considering the danger and complexity of handling these, cleaning agents Is not preferable.

On the other hand, the water-based cleaning agent is less dangerous and less toxic than the solvent-based cleaning agent, and has an excellent cleaning power by appropriately selecting the cleaning agent constituents such as surfactants and builders. Can be made. However, in this water-based cleaning agent, when the cleaning agent component excluding water adheres to the cleaning object and is washed out at, for example, 70% or more, the amount of cleaning solution taken out in the rinsing step becomes large, and the excessive cleaning agent It has the drawback of requiring replenishment. In addition, even when used after diluting with water, the solubility in water is generally good, so it is not easy to maintain and manage the cleaning performance of the cleaning liquid, and it is necessary to replenish the cleaning agent in excess to ensure the cleaning performance. However, there is a drawback in that the waste water treatment of the cleaning liquid after cleaning is also extremely bad. The treatment can be carried out by using, for example, coagulating sedimentation, pressure floating, activated sludge, activated carbon treatment method, etc., but each treatment method requires a great deal of cost and equipment.

Therefore, electronic parts or precision parts, which do not require such a large processing cost and equipment, can easily maintain and manage the cleaning property of the cleaning liquid, and are economically excellent in the amount of the cleaning agent used, etc. There has been a desire for a method of cleaning the.

[0006]

Under such circumstances, the inventors of the present invention have conducted diligent research, and as a result, by using a water-diluted solution of a specific cleaning agent, by adding mechanical force or the like at a temperature of 20 to 100 ° C. If it is kept in a non-separated uniform state, it has sufficient detergency, and can easily separate and remove oily stains in the washing liquid after washing and organic substances such as active ingredients in the detergent, resulting in remarkable wastewater treatment properties. It was found that the washing liquid after being improved and separated and removed can be reused. That is, since the organic substances in the cleaning liquid after cleaning can be efficiently separated and removed to a high concentration, the total amount of organic substances discharged per unit time separated and removed from the cleaning liquid after cleaning can be detected and The cleaning solution is replenished with an amount of active ingredients corresponding to the ratio of the active ingredients in the total organic matter required to maintain at least the detergency of the cleaning solution, and the aqueous phase after the separation treatment is circulated for reuse. The present invention has been completed by finding that the cleaning agent concentration can be maintained constant and the cleaning performance of the cleaning liquid can be maintained.

That is, the gist of the present invention is as follows: (1) In a cleaning method for cleaning electronic parts or precision parts with a cleaning agent, a water diluting solution of a cleaning agent having the following active ingredients and properties is used to prepare 20 to 100 A step of washing at a temperature of ℃ without phase separation (hereinafter abbreviated as a washing step), and a step of separating organic substances in the washing liquid while keeping the washing liquid after washing at 20 ° C. or more (hereinafter abbreviated as a separating step) A method for cleaning electronic parts or precision parts, characterized in that: Active ingredient: a nonionic surfactant alone, or a straight chain or branched chain having 6 to 30 carbon atoms in addition to the nonionic surfactant Saturated or unsaturated hydrocarbon compounds having 6 to 40 carbon atoms
In combination with one or more compounds selected from the group consisting of alkyl esters of 6 to 40 and alkyl ketones having 6 to 40 carbons Properties: The detergent is diluted with water or water is evaporated to change the content ratio of the active ingredient. 20 to 100% aqueous solution
The property that 30% by weight or more of the contained active ingredient is separated from the aqueous phase when left standing for 30 minutes at a temperature of ℃ (2) The inorganic salts in the detergent should be 0.1% or less. (1) The cleaning method according to (1), (3) characterized in that the remaining aqueous phase obtained by separating and removing organic substances from the cleaning liquid after cleaning is reused for dilution of the cleaning agent (1) or (2) And (4) an amount corresponding to the ratio of active components in the total organic matter necessary for at least maintaining the detergency of the cleaning solution by detecting the total amount of discharged organic matter separated and removed from the cleaning solution after washing. (3) A cleaning method characterized by replenishing the cleaning liquid with the active ingredient of (1) and recycling the aqueous phase after the separation treatment, (5) of oils and fats, machine oils, cutting oils, greases, waxes, liquid crystals, and fluxes. Characterized by cleaning attached electronic parts or precision parts The cleaning method according to any one of (1) to (4).

The cleaning agent used in the cleaning step in the present invention has the following active ingredients and properties. (1) Active ingredient: a nonionic surfactant, a linear or branched saturated or unsaturated hydrocarbon compound having 6 to 30 carbon atoms, an alkyl ester having 6 to 40 carbon atoms, and 6 to 6 carbon atoms. One or more compounds selected from the group consisting of 40 alkyl ketones (2) Properties: 20 to 1 of an aqueous solution in which the cleaning agent is diluted with water or water is evaporated to make the content of the active ingredient 10% by weight.
The property that 30% by weight or more of the contained active ingredient is separated from the aqueous phase when left standing for 30 minutes at a temperature of 00 ° C.

The detergent used here is not particularly limited as long as it has the above-mentioned active ingredients and properties. That is, a nonionic surfactant is an essential component as an active ingredient, and the nonionic surfactant may be used alone, or in addition to the nonionic surfactant, a linear or branched chain having 6 to 30 carbon atoms. Saturated or unsaturated hydrocarbon compounds, alkyl esters having 6 to 40 carbon atoms,
And one or more compounds selected from the group consisting of alkyl ketones having 6 to 40 carbon atoms.

For example, a nonionic surfactant having a cloud point of 100 ° C. or lower, a hydrocarbon compound used for improving detergency against oily stains, sparingly water-soluble alkyl esters and alkyl ketones. Such as
Examples of the detergent include 50% by weight or more of the organic component in the detergent composition. Among these, in order to improve the cleaning property, 70% of these components are used as organic components in the cleaning composition.
It is more preferable that the content is at least wt%. Here, the cloud point means that when 10 to 30 ml of a detergent composition diluted 20 times with ion-exchanged water is put into a test tube and the temperature is raised at a temperature rising rate of 1 ° C./minute, the liquid becomes cloudy. When the temperature exceeds this temperature, the nonionic surfactant in the aqueous solution is gradually separated from the aqueous phase.

Examples of the nonionic surfactants include ether types such as alkyl ether type, alkyl allyl ether type and alkyl thioether type; ester type such as alkyl ester type and sorbitan alkyl ester type; polyoxyalkylene alkyl amines and the like. Condensation type with amine; Condensation type with amide such as polyoxyalkylene alkyl amide; Pluronic or Tetronic type obtained by random or block condensation of polyoxyethylene and polyoxypropylene; Surfactant such as polyethyleneimine type . Among these, those having a hydrocarbon group having 4 to 22 carbon atoms are particularly preferable, and a detergent composition containing such a nonionic surfactant has an increased affinity for oily stains and a detergency. As well as improving, the cleaning solution mixed with this tends to show a clear cloud point,
Wastewater treatment is particularly good.

As the hydrocarbon compound, for example, paraffins, olefins, or aromatics or fats having a linear or branched saturated or unsaturated bond having 6 to 30 carbon atoms which is liquid at the temperature of the washing step are used. Examples include hydrocarbon compounds containing a ring group. Further, as the alkyl ester, for example, a carbon number of 6 to 40 which is liquid at the temperature of the washing step.
And monoesters, diesters, and triesters of C6-18, especially higher fatty acids having 6-18 carbon atoms and 1-18 carbon atoms.
Ester of higher alcohol; ester of higher fatty acid having 6 to 18 carbon atoms and diol or triol having 2 to 8 carbon atoms; higher alcohol having 1 to 18 carbon atoms and 2 to 8 carbon atoms
Esters with dicarboxylic acids or tricarboxylic acids are preferred. As the alkyl ketones, dialkyl ketones having 6 to 40 carbon atoms are preferable.

The detergent composition contains, in addition to these components, anionic surfactants, amines such as alkanolamines, builders, chelating agents, rust preventives, defoaming agents, etc., if necessary. You can also use the ones that do.

In the above-mentioned properties of the detergent of the present invention, if the amount of the active ingredient separated from the aqueous phase is less than 30% by weight, the active ingredient is not sufficiently separated from the washing liquid after washing, resulting in oil stains. Organic stain components such as are easily dissolved, emulsified and dispersed in the aqueous phase, and the wastewater treatment property is not sufficiently improved. Further, even if the aqueous phase after the separation treatment is reused as a diluting liquid of the washing liquid, the content of organic substances such as oil stains is large, re-contamination of the washing liquid is caused, and the maintenance of the washing performance is significantly reduced. Therefore, in order to more effectively improve the wastewater treatment property and enable the reuse of the cleaning liquid after cleaning, a cleaning agent in which 70% by weight or more of the contained active ingredient is separated is used. Is preferred. Here, the amount of the active ingredient separated from the aqueous phase is measured by COD or TOC (total organic carbon).

Further, in the electronic parts or precision parts to be cleaned in the present invention, caustic soda, sodium orthosilicate, sodium carbonate or phosphorus contained in the cleaning agent from the viewpoints of safety and electrical reliability of the members. 1% or less of inorganic salts such as acid soda, preferably 0.1%
The following is preferable. If the content of the inorganic salts exceeds 1%, the amount of the active ingredient separated from the washing liquid after washing decreases.

The washing step in the present invention is not particularly limited, but a temperature of 20 to 100 ° C., preferably 20 to 70 ° C. is obtained by using the detergent composition having the above-mentioned active ingredients and properties. In order to keep the cleaning liquid in a temperature range where it does not undergo phase separation, it is possible to circulate and stir with, for example, a stirring blade or a pump, and perform the immersion method, the ultrasonic cleaning method, the shaking method, the spray method, etc. alone or in combination. it can.

In the step of separating the washing liquid after washing, the washing liquid after washing is washed at 20 to 100 ° C., preferably 20 to 7
By heating or cooling to 0 ° C. and keeping the temperature at 20 ° C. or higher, organic substances in the cleaning liquid are separated and removed. The term "organic matter" as used herein means that the active ingredient in the cleaning agent that is separated and various organic soiling ingredients are included. In order to heat the cleaning liquid to 100 ° C or higher, equipment such as pressurization is required, which is not practically useful, and in order to lower the temperature below 20 ° C, cooling equipment or the like must be installed in the summer. Not practically effective. In particular, it is preferable to heat to a temperature above the cloud point of the nonionic surfactant to be used because the separation can be performed more effectively. That is, at temperatures above the cloud point, the nonionic surfactant loses water solubility, and as a result, oily stains that have been solubilized or emulsified in the cleaning liquid cannot be retained in water, and oily stains Depending on the size of its specific gravity, it floats or sinks in water and separates. Further, the nonionic surfactant itself loses water solubility and is separated from water.

The separated organic matter is composed of, for example, an active ingredient such as a nonionic surfactant, a hydrocarbon compound and the like, and an oily stain ingredient. Removal of such an organic matter is carried out by a washing tank after the washing or is separated. In a dedicated tank for, while maintaining at 20 ℃ or more, preferably 20 ~ 70 ℃, skimming method, method using a separation membrane, centrifugation method, electrical separation method or the like alone or in combination of two or more. Can be done by

Since the cleaning liquid after cleaning is cleaned by efficiently separating the organic substances in this way, the remaining aqueous phase obtained by separating and removing the organic substances from the cleaning liquid should be reused for dilution of the cleaning agent. You can Upon reuse, ion exchange treatment or adsorption treatment with activated carbon may be carried out, if necessary, in order to remove water-soluble ions in the cleaning liquid and organic substances such as surfactants.

Further, in the present invention, since the organic substances can be efficiently separated in this manner at a high concentration,
All the cleaning liquids after cleaning can be batch-separated and reused. Alternatively, a part of the washing liquid after washing is separated, and the total amount of organic substances separated and removed from the washing liquid is detected, which corresponds to the ratio of the active components in the total organic substance required to maintain at least the washing property of the washing liquid. It is also possible to continuously maintain the detergency of the washing liquid by replenishing the washing liquid with an amount of the active ingredient and recycling the aqueous phase after the separation treatment. Here, the total discharged amount of organic substances means the discharged amount of all organic substances including the active component and various organic fouling components in the separated cleaning agent. This discharge amount can be measured by weight or volume measurement.
In addition, the ratio of the active ingredient in the total organic matter required to maintain at least the detergency of the detersive liquid means the weight of the minimum amount of the active ingredient necessary to maintain detergency with respect to the weight or volume of the soil component and the active ingredient. Or, it means the ratio of volume.

Further, if necessary, two or more of the present methods may be used in combination, or may be used in combination with other commonly used cleaning methods. Further, a rinsing step may be provided if necessary, and examples thereof include the rinsing methods described in JP-A-4-12480 and JP-A-5-96255.

The cleaning method of the present invention has a particularly excellent effect when cleaning precision parts and jigs and tools used in the assembly and processing steps thereof. Here, the precision parts are, for example, electronic parts, electric parts, Precision machine parts, resin processed parts, optical parts, etc. Electronic components include, for example, printed wiring boards used in computers and their peripheral devices, home appliances, communication devices, office automation equipment, and other electronic application devices; used as contact members such as IC lead frames, resistors, capacitors, and relays. Hoop materials; Liquid crystal displays used in office automation equipment, watches, computer systems, toys, home appliances, etc .; Magnetic recording parts used in video / audio recording / reproducing parts and related parts; Semiconductors such as silicon and ceramic wafers Materials: Electrostrictive parts such as crystal oscillators; photoelectric conversion parts used in CDs, PDs, copying machines, optical recording machines, etc. The electric parts refer to, for example, electric motor parts such as brushes, rotors, stators, and housings; ticket issuing parts used in vending machines and various devices; currency inspection parts used in vending machines, cash dispensers, and the like. Precision equipment parts include, for example, bearings used in precision drive equipment, video recorders, etc .; machining parts such as cemented carbide chips. The resin-processed parts refer to precision resin-processed parts used in, for example, cameras and automobiles. Further, the optical component refers to, for example, a lens used in a camera, spectacles, an optical device or the like, and other components include, for example, a spectacle frame, a watch case, a watch belt or the like. In addition, jigs and tools used in the assembly processing step include jigs and tools handled in various steps such as manufacturing, molding, processing, assembling and finishing of precision parts as shown in the above-mentioned various parts examples, It refers to various equipment that handles these precision parts, parts thereof, and the like.

The cleaning method of the present invention exerts a suitable performance especially when cleaning waxes such as liquid crystal adhered to the flux remaining liquid crystal or fixed wax containing rosin among the above, among others. The precision parts and jigs and tools to which the present invention is applied are not limited to these examples, and may interfere with subsequent process interfering substances such as various processing oils and fluxes in the assembly process, or may reduce product characteristics. The cleaning method of the present invention can be applied to precision parts and jigs having a solid surface of a certain shape to which various oily pollutants to be adhered are attached. The characteristics of the cleaning method of the present invention are particularly exerted when these contaminants are mainly organic oil stains such as fats, oils, machine oils, cutting oils, greases, liquid crystals, and rosin flux. Furthermore, it is effective even if the dirt is a mixture of these with metal powder, inorganic powder and the like.

[0024]

EXAMPLES Next, the present invention will be described in more detail with reference to examples, but the present invention is not limited to these examples.

Example 1 A detergent composition having the composition shown in Table 1 was prepared, and these were diluted with ion-exchanged water so that the active ingredient content was 10% by weight. Let stand for 30 minutes at temperature. As a result, the cleaning composition No. It was confirmed that in each of 1 to 4, 30% by weight or more of the contained active ingredient was separated from the aqueous phase (85 and 7 respectively).
3, 70, 80%). On the other hand, in cleaning composition 5 and 6, it is 0
%, 10%. The amount of the active ingredient separated from the aqueous phase was measured by COD.

Then, a printed circuit board (10 cm × 15 cm) treated with a rosin-based flux (test material 1), a naphthene-based mineral oil (40 ° C., 350 cSt) using a 10-fold diluted solution of the cleaning composition shown in Table 1 was used. ) Is applied (1 g / m
² ) The steel test piece (10 cm × 15 cm) [test material 2] and the glass substrate (10 cm × 10 cm) [test material 3] coated with liquid crystal (5 g / m ² ) were washed.
The washing was performed at 50 ° C. for 3 minutes with ultrasonic stirring while stirring with a stirring blade so as not to cause phase separation. Each of the cleaned plates (test materials 1 to 3) after cleaning was immersed in ion-exchanged water at 40 ° C., and rinsed (rinsed) while applying ultrasonic waves for 1 minute. The washed plates (test materials 1 to 3) after rinsing all had good appearance.

Then, the used washing solution is put in a beaker, kept at 50 ° C., and stirred at 2 L / M while stirring so as not to cause phase separation under the same conditions as the above washing.
6 cm ² ) and the lower layer solution is returned to the beaker again and the cleaning solution after circulating treatment for 30 minutes is sampled to measure its COD (chemical oxygen demand) (A value), and the COD (B value) of the cleaning solution before the treatment is measured. ) And the separation rate of organic matter ((B value-A value) / B value) x 100 was calculated. Next, each cleaning composition was diluted 10 times using the aqueous phase after circulating treatment for 30 minutes, and the cleaning and rinsing were performed under the same conditions as above, and the removability of contaminants at that time was evaluated. The results are shown in Table 1. The evaluation criteria of the removability of dirt substances are as follows.

Evaluation criteria for removability of contaminants: ◎; contaminants (flux, naphthenic mineral oil or liquid crystal)
Very good with no residue. ◯: Good with almost no residual dirt. Δ: Slightly unacceptable, with some residual dirt substances.

[0029]

[Table 1]

As is clear from the results in Table 1, the cleaning compositions 1 to 4 have a high organic matter separation rate even under stirring conditions having good cleaning properties, and the cleaning liquids obtained by separation are obtained. Since COD was low, it was confirmed that organic matter was low. In addition, a separation rate of 50% or more (cleaning composition 1
4) showed good detergency even if the aqueous phase was reused for diluting the detergent, and those having a separation rate of 80% or more (detergent compositions No. 1, 2 and 4) were excellent. .

[0031]

EFFECTS OF THE INVENTION According to the present invention, the organic substances in the cleaning liquid after cleaning can be efficiently separated and removed to a high concentration, and the subsequent wastewater treatment process can be simplified.
It is possible to industrially advantageously clean electronic parts or precision parts to which dirt such as cutting oil, grease, wax, liquid crystal, or flux adheres. Further, the aqueous phase separated according to the present invention can be used again for diluting the cleaning agent, and the amount of water used for diluting the cleaning agent can be significantly reduced, and the total organic matter emission amount separated and removed can be reduced. On the other hand, by supplying a fixed ratio of the active ingredient, the cleaning property of the cleaning liquid can be maintained, the amount of the cleaning agent used can be reduced, and it is economically excellent.

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[Procedure amendment]

[Submission date] February 8, 1994

[Procedure Amendment 1]

[Document name to be amended] Statement

[Name of item to be corrected] 0015

[Correction method] Change

[Correction content]

Further, in the electronic parts or precision parts to be cleaned in the present invention, caustic soda, sodium orthosilicate, sodium carbonate or phosphorus contained in the cleaning agent is included from the viewpoint of safety and electrical reliability of the members. 1% or less of inorganic salts such as acid soda, preferably 0.1
% Or less is desirable .

Claims (5)

[Claims] 1. A cleaning method for cleaning electronic parts or precision parts with a cleaning agent, which uses a water diluting solution of a cleaning agent having the following active ingredients and properties to prevent phase separation at a temperature of 20 to 100 ° C. A method for cleaning electronic parts or precision parts, comprising: a step of cleaning with a cleaning solution; and a step of separating organic substances in the cleaning solution while keeping the cleaning solution after cleaning at 20 ° C. or higher. Active ingredient: Nonionic surfactant alone, or in addition to the nonionic surfactant, a linear or branched saturated or unsaturated hydrocarbon compound having 6 to 30 carbon atoms, 6 to 40 carbon atoms
In combination with one or more compounds selected from the group consisting of alkyl esters of 6 to 40 and alkyl ketones having 6 to 40 carbons Properties: The detergent is diluted with water or water is evaporated to change the content ratio of the active ingredient. 20 to 100% aqueous solution
A property that 30% by weight or more of the contained active ingredient is separated from the aqueous phase when left standing for 30 minutes at a temperature of ℃ 2. The cleaning method according to claim 1, wherein the content of the inorganic salts in the cleaning agent is 0.1% or less. 3. The cleaning method according to claim 1 or 2, wherein the remaining aqueous phase obtained by separating and removing organic substances from the cleaning liquid after cleaning is reused for dilution of the cleaning agent. 4. A discharge amount of all organic substances separated and removed from the washing liquid after washing is detected, and an amount of active components corresponding to the ratio of active components in the total organic substances necessary for maintaining at least the detergency of the washing liquid is determined. The cleaning method according to claim 3, wherein the cleaning liquid is replenished and the aqueous phase after the separation treatment is circulated and used. 5. The cleaning method according to claim 1, wherein electronic parts or precision parts to which oils and fats, machine oils, cutting oils, greases, waxes, liquid crystals, fluxes are attached are washed. .