JP2010137134A - Cleaning method and cleaning apparatus under low environmental load - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a cleaning method which is under a low environmental load and has a higher cleaning power, a cleaning unit performing the method, and a cleaning apparatus incorporating the cleaning unit. <P>SOLUTION: In the cleaning method, microbubbles are generated in electrolytic alkaline water as a cleaning solution, and the solution is intermittently irradiated with ultrasonic wave therein. The cleaning unit includes a cleaning tank (102) storing the electrolytic alkaline water as the cleaning solution, a microbubble generating nozzle (103) generating the microbubbles in the cleaning tank (102), and an ultrasonic oscillator irradiating the electrolytic alkaline water stored in the cleaning tank (102) with the ultrasonic wave therein. The cleaning apparatus includes a cleaning unit cleaning the cleaning object, a rinse unit removing the cleaning solution attached to the cleaning object, and a drying unit dewatering and drying the cleaning object, wherein the above cleaning units is used as the cleaning unit. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention is a method of cleaning a low environmental load for general industrial parts such as various substrates in a field where a cleaning liquid containing a trace amount of inorganic alkali can be applied to a cleaning process in a manufacturing process, and machined parts. And a cleaning device.

  In recent years, in the field of cleaning, techniques of electrolytic alkaline water and microbubbles have been developed for the purpose of reducing the environmental burden. Furthermore, electrolytic alkaline water as a cleaning liquid, electrolytic alkaline water production apparatus, microbubble generating nozzle, or a microbubble generating unit incorporating a pump is becoming commercially available. A cleaning method and a cleaning apparatus to which these techniques are applied are disclosed in, for example, the following patent documents.

  Patent Document 1 discloses a cleaning method and a cleaning apparatus having a cleaning process (liquid temperature: 40 to 90 ° C.), liquid draining, and drying processes using electrolytic alkaline water as a cleaning liquid.

  Patent Document 2 discloses a cleaning apparatus having an air blocking cleaning with electrolytic alkaline water as a cleaning liquid (the liquid temperature is increased in response to a change in pH or emulsification degree of the cleaning liquid), rinsing, and drying.

  Patent Document 3 discloses a cleaning method and a cleaning apparatus for ultrasonic cleaning using air bubbling electrolytic alkaline water as a cleaning liquid.

  Patent Document 4 discloses a cleaning device for ultrasonic cleaning (determination of cleaning time and liquid replenishment is performed by sound pressure and pH monitoring) using electrolytic alkaline water as a cleaning liquid.

  Patent Document 5 discloses a cleaning apparatus for ultrasonic cleaning (cleaning liquid management based on oil concentration) using electrolytic alkaline water as a cleaning liquid.

  Patent Document 6 discloses a cleaning apparatus to which a processing liquid as a cleaning liquid, microbubbles (diameter 20 μm or less), and ultrasonic waves (5 to 100 MHz) are applied.

  Patent Document 7 discloses a batch-type and single-wafer-type cleaning methods and apparatuses using a liquid as a cleaning liquid, microbubbles (predetermined gas), and ultrasonic waves.

  Patent Document 8 discloses a cleaning method and a cleaning apparatus using pure water at room temperature as a cleaning liquid, nitrogen gas microbubbles (30 ppm or more), and ultrasonic waves.

  Patent Document 9 discloses a cleaning apparatus having a configuration of an interface control agent-added aqueous solution, microbubbles, and oil-water separation as a cleaning liquid.

JP-A-10-192860 JP 2001-286835 A JP 2002-320934 A JP 2005-013886 A JP 2005-262155 A Japanese Patent Laid-Open No. 2005-093873 JP 2006-179765 A JP 2006-310456 A JP 2007-301529 A

  A known low-environmental load compatible microbubble application cleaning method and cleaning apparatus are disclosed as described above, which uses electrolytic alkaline water as a cleaning liquid, combined electrolytic alkaline water and ultrasound, and microbubble water. Although it is the content of combining microbubble water and ultrasonic waves as a cleaning liquid, as a result of evaluating the degreasing ability as a cleaning power by the present inventors, in any of the above cases, satisfactory satisfaction cannot be obtained. It was.

  Accordingly, an object of the present invention is to provide a cleaning method with a low environmental load and a higher cleaning power, a cleaning unit for performing the method, and a cleaning apparatus incorporating the cleaning unit.

  The cleaning method of the present invention includes a step of generating microbubbles in electrolytic alkaline water as a cleaning liquid, and a step of intermittently irradiating the microbubble electrolytic alkaline water with ultrasonic waves.

  Further, the cleaning unit of the present invention for carrying out this cleaning method includes a cleaning tank for storing electrolytic alkaline water as a cleaning liquid therein, and a microbubble generating nozzle for generating microbubbles in the cleaning tank. And an ultrasonic transducer capable of irradiating ultrasonic waves in the electrolytic alkaline water stored in the cleaning tank.

  Furthermore, the cleaning apparatus of the present invention includes a cleaning unit for cleaning an object to be cleaned, a rinse unit for removing the cleaning liquid adhering to the liquid to be cleaned, and a drying unit for draining and drying the object to be processed. The above cleaning unit is used as the cleaning unit.

  A feature of the present invention resides in a cleaning method in which electrolytic alkaline water, microbubbles, and ultrasonic waves are combined, and a cleaning apparatus for performing the cleaning method.

  According to the cleaning method of the present invention, it is possible to remarkably improve the cleaning power such as degreasing and particle removal and cleaning uniformity for various objects to be processed. The liquid temperature does not need to be as high as normal temperature (about 25 ° C.), and the consumption of electrolytic alkaline water as a cleaning liquid due to evaporation or the like can be reduced.

  Furthermore, electrolytic alkaline water contains only a trace amount of inorganic substances, and its main component is water. Therefore, unlike conventional non-aqueous and semi-aqueous cleaning liquids, the burden on the environment is extremely low.

  In the cleaning method of the present invention, first, using electrolytic alkaline water having a liquid temperature of room temperature (about 25 ° C.) as a cleaning liquid, microbubbles are generated in the electrolytic alkaline water, and the electrolytic water is stored. An object to be processed is placed in the tank, and thereafter, ultrasonic waves are intermittently irradiated into the liquid, thereby removing oils and particles adhering to the object to be processed.

  And in the washing | cleaning unit of this invention for implementing this method, while providing the washing tank for storing the electrolytic alkaline water as a washing | cleaning liquid inside, the micro for generating microbubble in the electrolytic alkaline water in a washing tank A bubble generating nozzle is provided, and further, an ultrasonic vibrator is provided for irradiating the electrolytic alkaline water in the washing tank with ultrasonic waves, thereby crushing the microbubble electrolytic alkaline water.

  In the cleaning apparatus of the present invention, the cleaning apparatus includes a cleaning unit for cleaning the object to be cleaned, a rinse unit for removing the cleaning liquid attached to the liquid to be cleaned, and a drying unit for draining and drying the object to be processed. In the above, the cleaning unit is used as the cleaning unit.

  An embodiment of the cleaning method of the present invention will be described. In the cleaning method of this embodiment, first, electrolytic alkaline water is stored in the cleaning tank 102, and microbubbles are generated in the electrolytic alkaline water. Put the object to be processed into.

  Next, ultrasonic waves are intermittently applied to the electrolytic alkaline water in which the microbubbles are generated. Then, by this, the microbubbles are crushed and oils and particles adhering to the object to be processed are removed.

  Next, an embodiment of the cleaning unit of the present invention for carrying out this method will be described with reference to FIG. 1. FIG. 1 is a diagram showing a configuration of the cleaning unit 100 of the present embodiment.

  The cleaning unit of this embodiment includes an ultrasonic cleaning tank 102 (frequency: 35 KHz) provided with an ultrasonic vibrator, and a microbubble generating nozzle for generating microbubbles in the cleaning liquid in the ultrasonic cleaning tank 102. 103, a reliable pump 104 even if gas is mixed, a heat exchanger 105 for adjusting the temperature of the cleaning liquid, a constant temperature water circulation device 106, a water flow meter 107, an air flow meter 108, Ball valves 109 and 110, a needle valve 111, and pressure gauges 112 and 113 are provided. Electrolytic alkaline water is stored as the cleaning liquid 101 in the ultrasonic cleaning tank 102.

  The cleaning liquid 101 is circulated by the pump 104, and is adjusted to a predetermined pressure and flow rate by inverter control of the ball valves 109 and 110, the needle valve 111 and the pump 104.

  Further, in the equipment configuration of the cleaning unit 100, the indication value of the pressure gauge 112 is 0.4 MPa, the indication value of the pressure gauge 113 is 0.3 MPa, the indication value of the water flow meter 107 is 16 L / min, and the air flow meter The indicated value 108 is 0.8 NL / min.

  Further, the liquid temperature is adjusted to 24 to 25 ° C. by the heat exchanger 105 and the constant temperature water circulation device 106. As a result, the cleaning liquid 101 has a cloudy appearance.

  Next, the evaluation results of the cleaning method of this example will be described. In the evaluation of the cleaning method of this example, the detergency as the degreasing ability is a wetting index standard solution (manufactured by Wako Pure Chemical Industries, Ltd.) having various surface tensions ( JIS K6768) was obtained, applied to a test piece (solid surface) with a cotton swab, and an evaluation method for judging the wettability at that time.

  The obtained standard solutions have surface tensions of 32 mN / m, 34 mN / m, 36 mN / m, 37 mN / m, 38 mN / m, 42 mN / m, 45 mN / m, 50 mN / m, 52 mN / m and 62 mN / m. It was supposed to be. It means that as the standard solution having a larger surface tension gets wet, the amount of residual oily substance is smaller.

  In JP-A-11-217598, there is a correlation between the critical surface tension obtained with a wetting index standard solution manufactured by Wako Pure Chemical Industries and the amount of oily substance measured with a Fourier integral infrared spectrometer (JIR-WINSPEC50 manufactured by FT-IR JEOL). It is disclosed that there is a relationship. It is shown as a relative value when the amount of residual oily substance on the solid surface wetted by water (25 ° C.) having a surface tension of 72 mN / m is “1”. For reference, the correlation diagram is shown in FIG. 2, and the critical surface tension means the value of the surface tension of the standard solution that gets wet at the boundary between the wet and non-wetting of the solid surface.

  In addition, the cleaning power as the particle removal capability has the effect of peeling off particles adhering to the object to be processed and preventing re-adhesion to the object due to the adhesion of particles to the microbubbles if there is a degreasing ability. Therefore, degreasing ability and particle removal ability were judged to be equivalent.

The test piece preparation method will be described with reference to FIG. 3. First, a test piece is prepared, oil is applied to the test piece with a cotton swab, industrial wiper is wiped, and then heat treatment (80 ° C. × 2 hours) After that, the degreasing ability was evaluated after washing, rinsing with city water, and draining with an air gun. The test piece was a SUS304 stainless steel plate (57 ^mm × 40 ^mm × ^t 1.5 ^mm ), and the oil was lubricating oil (zero additive product manufactured by Shin Nippon Oil Co., Ltd.).

  Next, the cleaning process sequence for evaluating the cleaning method of the present embodiment will be described with reference to FIG. 4. The cleaning method A is the content of the present invention, and ultrasonic waves are intermittently applied to the microbubbles. This is a processing sequence for crushing. On the other hand, the cleaning method B is a processing sequence when the microbubble generating nozzle 103 is removed, and is to be compared with microbubble collapse.

Incidentally, in the cleaning unit 100, _{t 1} is 15 seconds, _{t 2} is set for 60 seconds. Although setting rationale is by visual determination, t ₁ is in the microbubbles crushed (disappearance) in about 10 seconds, t ₂ is to return to the original opaque state in about 30 seconds.

  Here, the cleaning method and the oil peeling phenomenon by visual observation will be described. In FIG. 5, the posture of the test piece is perpendicular to the vibrator, and the oil due to the difference in the cleaning method when lubricating oil is used as the oil. Indicates the difference in the peeling phenomenon. In order to clarify the phenomenon, city water was used as the cleaning liquid 101.

  In FIG. 5, in the case of the cleaning method A, first, a large amount of microbubbles adhere to dirt such as oil. Thereafter, when an ultrasonic wave is irradiated, as shown in FIG. 5, the film is peeled off in a short time so as to be turned from the vibrator side toward the liquid surface.

  On the other hand, the cleaning method B is a general ultrasonic cleaning, and peels in an uneven state due to the influence of standing waves. This is a phenomenon that has been known for a long time, and a cleaning apparatus incorporating a workpiece swinging mechanism or an ultrasonic frequency sweep is commercially available. The cleaning method A has an advantage that such a countermeasure is unnecessary.

  Next, FIG. 6 shows the difference in the oil peeling phenomenon due to the difference in the cleaning method when the posture of the test piece is horizontal to the vibrator and the lubricating oil is used as the oil. Electrolytic alkaline water is used as the cleaning liquid 101, and the treatment time is 2 minutes, 5 minutes, and 10 minutes.

  In the case of the cleaning method A, no unevenness is observed. On the other hand, in the cleaning method B, unevenness is observed at the center of the test piece in any case. However, if the processing time is increased, the degree of light unevenness is reduced.

  From the above experimental facts, it has been proved that a crushing cleaning method combining microbubbles and ultrasonic waves is extremely effective for uniform cleaning. Therefore, mechanical (oscillation mechanism, etc.) and electrical (frequency sweep, etc.) countermeasures are not required, and an inexpensive device policy is possible.

  Next, the degreasing capacity will be described. FIG. 7 shows the degreasing capacity of the cleaning liquid 101 (electrolytic alkaline water and city water) when the cleaning method A, the oil is lubricating oil, and the liquid temperature is 24 to 25 ° C.

  Any unevenness by visual observation is not a problem, but there is a clear difference in degreasing ability. In the case of electrolytic alkaline water, the critical surface tension is about 50 to 52 mN / m, and the amount of residual oily substance (relative value) is 1.5 or less according to FIG. Very satisfied. In the case of city water, since the wetting index standard solution 50 mN / m does not get wet, it is not preferable as the cleaning liquid 101.

  Thus, the cleaning method combining electrolytic alkaline water, microbubbles, and ultrasonic waves is very excellent. However, there is a drawback that the processing time requires a little longer time. Therefore, this cleaning method is optimally incorporated into a batch type cleaning apparatus, but of course, it can also be incorporated into a single wafer type cleaning apparatus if the processing time is acceptable. However, in general, in the case of a single wafer cleaning apparatus, the commercial value of the apparatus is low unless the processing time is in seconds.

(First form)
The first embodiment of the embodiment of the cleaning apparatus of the present invention will be described with reference to FIG. 8. The cleaning apparatus of the present embodiment removes a cleaning unit for cleaning an object to be cleaned and a cleaning liquid adhering to the liquid to be cleaned. In the cleaning apparatus provided with the rinsing unit for carrying out and the drying unit for draining and drying the object to be processed, the above-described cleaning unit is used as the cleaning unit. That is, the cleaning apparatus incorporates a cleaning unit for performing a cleaning method using a combination of microbubbles and ultrasonic waves while using electrolytic alkaline water as cleaning water.

  And this form is a batch type cleaning device that performs a cleaning process while transferring a basket or cassette on which a workpiece is mounted. Ideal for low environmental load cleaning treatment of small-sized substrates.

  The basic configuration 200 includes a loader 200-1, a cleaning unit 200-2, a rinse unit 200-3, a drying unit 200-4, an unloader 200-5, and a transfer machine 200-6. The cleaning unit of the present invention is incorporated in the cleaning unit 200-2.

  The rinsing unit 200-3 is intended to rinse the cleaning liquid with pure water, but is manufactured with existing technology such as quick dump, spray, shower, etc., alone or in combination. The drying unit 200-4 is also manufactured using existing techniques such as vacuum drying and hot air drying.

  The cleaning unit 200-2 includes an overflow type cleaning tank 201 to which an ultrasonic vibrator 202 and a microbubble generating nozzle 203 are attached, a circulation of electrolytic alkaline water 215 and a pump 205 for containing air therein, and electrolytic alkaline A heat exchanger 206 and a constant temperature water circulation unit 207 for adjusting the temperature of the water 215 to room temperature, a buffer tank 204 for optimally establishing the circulation system, and dirt (oil, particles) from the cleaning tank 201 flowing into the water tank 215 Etc.) for removing the soil recovery unit 214 and the electrolytic alkaline water supply unit 213.

  Instead of this supply unit, an electrolytic alkaline water production apparatus may be arranged. The ultrasonic transducer 202 described above may be a throwing type. Further, the microbubble generating nozzle 203 needs to adjust the circulation system to the optimum flow rate and pressure depending on the type. For this purpose, a water flow rate detector 208, pressure detectors 209 and 210, an air flow rate detector 211, and a reduced pressure detector 212 are provided. The cleaning device having such a configuration has a cleaning power and is a low environmental load type.

  The load on the environment is only a small amount of oil generated from the dirt collection unit 214 because the cleaning unit 200-2 uses microbubble electrolytic alkaline water at room temperature and a circulation system. Here, the collection of dirt can be dealt with by applying an existing technique such as a coalescer, a UF membrane system or the like. A large amount of rinse liquid is discharged from the rinse unit 200-3. The electrolytic alkaline aqueous stock solution contains only a trace amount of inorganic alkali. In the rinsing step, the stock solution remaining in the object to be treated is rinsed and diluted with a large amount of pure water as viewed from the remaining solution. From this, it becomes the drainage which cleared the water pollution prevention law drainage standard.

(Second form)
The second embodiment of the embodiment of the cleaning apparatus of the present invention will be described with reference to FIG. 9. The cleaning apparatus of the present embodiment is also a cleaning unit for cleaning an object to be cleaned, as in the first embodiment. In the cleaning apparatus including the rinsing unit for removing the cleaning liquid adhering to the cleaning liquid and the drying unit for draining and drying the object to be processed, the above-described cleaning unit is used as the cleaning unit.

  The second embodiment is a single wafer cleaning apparatus that performs a cleaning process while transferring a workpiece in a horizontal or vertical posture, and is a low environment such as a relatively large glass substrate, quartz substrate, or ceramic substrate. Ideal for load-cleaning processes.

  The basic configuration 300 includes a loader 300-1, a cleaning unit 300-2, a rinse unit 300-3, a drying unit 300-4, an unloader 300-5, a transfer machine 300-6, and a roller transport mechanism 300-7. The cleaning unit of the present invention is incorporated in the cleaning unit 300-2, but the content is the same as in the first embodiment. In such a form, roller conveyance is common after rinsing. Accordingly, the rinsing unit 300-3 is manufactured with the contents of existing techniques such as spraying and showering with pure water alone or in combination. The drying unit 300-4 is also manufactured by an air knife method which is an existing technology.

  In the cleaning unit 300-2, when the workpiece is in a horizontal posture, when the workpiece is lowered and raised in the cleaning tank 201, a smooth operation can be ensured if the workpiece is in an inclined posture.

  The present invention is characterized by a combination of electrolytic alkaline water, microbubbles, and ultrasonic waves, thereby significantly improving the cleaning power such as degreasing and particle removal and the uniformity of cleaning for various objects to be processed. Various industrial substrates such as machined parts, etc., in various fields where it is allowed to apply a cleaning liquid containing a trace amount of inorganic alkali to the cleaning process of the manufacturing process. Applicable to general cleaning with low environmental impact.

It is a figure which shows the structure of the washing | cleaning unit of this invention. It is a correlation diagram of critical surface tension and residual oily substance amount (relative value). It is a figure for demonstrating the test piece preparation method. It is a figure for demonstrating a washing process sequence. It is a figure explaining a test piece attitude | position (vertical) and an oil peeling phenomenon. It is a figure explaining a test piece attitude | position (horizontal) and an oil peeling phenomenon. It is a figure explaining the degreasing capability by the combination of a washing | cleaning liquid, microbubble, and an ultrasonic wave. It is a figure for demonstrating the 1st form of the Example of the washing | cleaning apparatus of this invention. It is a figure for demonstrating the 2nd form of the Example of the washing | cleaning apparatus of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 100 Cleaning unit 101 Cleaning liquid 102 Ultrasonic cleaning tank 103 Micro bubble generation nozzle 104 Pump 105 Heat exchanger 106 Constant temperature water circulation device 107 Water flow meter 108 Air flow meter 109, 110 Ball valve 111 Needle valve 112, 113 Pressure gauge 200 Batch Basic configuration of cleaning apparatus 201 Cleaning tank 202 Ultrasonic vibrator 203 Micro bubble generating nozzle 204 Buffer tank 205 Pump 206 Heat exchanger 207 Constant temperature water circulation unit 208 Water flow detectors 209 and 210 Pressure detector 211 Air flow detector 212 Depressurization detection 213 Electrolytic alkaline water supply unit 214 Dirt recovery unit 215 Electrolytic alkaline water 300 Single wafer cleaning device basic configuration

Claims (4)

  A cleaning method characterized in that microbubbles are generated in electrolytic alkaline water as a cleaning liquid, and treatment is performed by intermittently irradiating ultrasonic waves in the liquid.   The cleaning method according to claim 1, wherein the temperature of the electrolytic alkaline water as the cleaning liquid is normal temperature (about 25 ° C.). A cleaning unit for carrying out the cleaning method according to claim 1 or 2,
A cleaning tank (102) for storing electrolytic alkaline water as a cleaning liquid therein;
A microbubble generating nozzle (103) for generating microbubbles in the cleaning tank (102);
A cleaning unit comprising: an ultrasonic vibrator capable of irradiating ultrasonic waves in electrolytic alkaline water stored in the cleaning tank (102).   A cleaning apparatus comprising a cleaning unit for cleaning an object to be cleaned, a rinse unit for removing the cleaning liquid adhering to the liquid to be cleaned, and a drying unit for draining and drying the object to be processed. 3. A cleaning apparatus using the cleaning unit according to 3.

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