JP3439243B2 - Cleaning method and cleaning device - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and apparatus for cleaning electrical or electronic components such as optical components made of glass or plastic, printed circuit boards, liquid crystal substrates, wafers or mechanical components.

[0002]

2. Description of the Related Art As a conventional method for cleaning an object to be cleaned as described above, 5 of "Precision cleaning device and latest applied technology" (published by Industrial Data Center Co., Ltd., issued November 8, 1991).
70-574. FIG. 5 shows a flowchart of this cleaning method, which includes a cleaning step 41 for cleaning the object to be cleaned with a cleaning solution, a rinse step 42 for flushing the cleaning solution from the object to be cleaned with water or pure water, and water and pure water from the rinse step 42. Process 43 of dehydrating the product with an alcohol such as isopropyl alcohol (hereinafter referred to as IPA)
And a drying step 44 in which alcohol is volatilized and dried after dehydration. In the final drying step 44, either drying with CFC vapor or drying with IPA vapor is performed.

[0003]

However, in the conventional cleaning method, the water vapor in the atmosphere is condensed and adheres to the surface of the object to be cleaned as water droplets, and this adhesion causes stains on the surface of the object to be cleaned. Occurs, resulting in poor cleaning. Adhesion of such water droplets remarkably occurs in the dehydration process using alcohol. Table 1 is a table comparing the latent heat of vaporization of hydrophilic solvents such as IPA with non-aqueous solvents such as CFCs.

[0004]

[Table 1]

As shown in Table 1, the hydrophilic solvent has a larger latent heat of vaporization than the non-aqueous solvent, and in the process of pulling up the article to be cleaned from the hydrophilic solvent and thereafter transporting it, the hydrophilic solvent evaporates due to evaporation of the hydrophilic solvent. The surface of the washed material is cooled rapidly.
This causes water vapor in the atmosphere to condense on the surface of the object to be cleaned,
Attaches as water drops. Since the water droplets contain a large amount of fine dust suspended in the air, even if the object to be cleaned is dried in the subsequent drying step, it remains as stains and causes poor cleaning.

In this case, it is conceivable to remove the water droplets adhering to the surface of the object to be cleaned with a non-aqueous solvent having a low evaporation latent heat. However, as shown in Table 2, the non-aqueous solvent is not preferable from the viewpoint that the solubility in water is extremely small, the attached water droplets cannot be removed, and the number of steps is increased.

[0007]

[Table 2]

[0008] From the above, the present invention provides a cleaning method capable of preventing water droplets from adhering to an object to be cleaned and enabling clean cleaning without generation of stains, and a cleaning apparatus capable of implementing this method. The purpose is to do.

[0009]

Means and Actions for Solving the Problems Cleaning of the Invention
The method comprises a step of performing a predetermined cleaning treatment on the object to be cleaned with a hydrophilic solvent, and a step of carrying the object to be cleaned in a dehumidified atmosphere and performing a predetermined cleaning treatment with a non-aqueous solvent.

The dehumidifying conditions in the present invention are based on IPA, and the absolute humidity is preferably 10 g / m ³ or less. In the case of other alcohols such as ethyl alcohol and methyl alcohol, the absolute humidity within this range is selected in relation to the latent heat of vaporization. For example, in the case of ethyl alcohol, the absolute humidity is 8.5 g / m ³ or less. In the case of humidity and methyl alcohol, an absolute temperature of 7.5 g / m ³ or less is good.

Further, the parent-aqueous solvents are, IPA, methyl alcohol, may be those selected from ethyl alcohol, it may be those of the vapor.

On the other hand, the non-aqueous solvent may be selected from chlorofluorocarbon, methylene chloride, trichloroethylene, 1,1,1-trichloroethane, perfluorocarbon, siloxane, and a hydrocarbon solvent, or vapors thereof. It may be.

In the above method, even if the hydrophilic solvent evaporates, water vapor will not be condensed on the surface of the object to be cleaned. FIG. 3 shows a phenomenon in which water droplets condense on the surface of the object to be cleaned. The vertical axis plots the water vapor pressure and absolute humidity in the air, and the horizontal axis plots the temperature. In the figure, the characteristic curve A is a vapor pressure curve at a relative humidity of 60% RH, and the characteristic curve B is a saturated vapor pressure curve of water.

Now, when the gas (P1) having relative humidity of 60% RH and temperature T1 ° C. (absolute humidity D1) is cooled, temperature T2 ° C.
Intersect with the saturated water vapor pressure curve at (P2). When it is further cooled, the moisture in the gas condenses into water droplets that appear on the surface of the object. Here, when the hydrophilic solvent evaporates, heat corresponding to the latent heat of vaporization is taken from the object, so that the hydrophilic solvent is rapidly cooled. For example,
When the IPA adhering to the surface of the plastic plate at 20 ° C. evaporates, the surface of the plastic plate is cooled to 1 ° C. in 30 seconds. As a result, the temperature of the gas near the object drops,
The temperature is further lowered below the temperature (T2) intersecting the saturated vapor pressure curve, and the moisture in the gas is condensed.

Such a phenomenon is more remarkable as the thermal conductivity or the specific heat of the material of the object is smaller. On the other hand, if dehumidification is performed to reduce the absolute humidity from D1 to D2,
The temperature at which the water condenses is T3 (P3), and the water will not condense unless cooled to a temperature lower than T2. As a result of repeating many experiments in the present invention,
When dehumidifying the absolute humidity in the atmosphere to 10 g / m ³ or less,
It has been found that the cleaning quality is substantially good.

The cleaning apparatus applied to the cleaning method of the present invention as described above is provided with a hydrophilic solvent and is applied to an object to be cleaned.
A cleaning tank that performs regular cleaning processing and a non-aqueous agent filled
It is provided with a cleaning tank for performing a predetermined cleaning process on the object to be cleaned, and a dehumidifying means for dehumidifying the upper space of the transfer device for transferring the object to be cleaned. Here, as the dehumidifying means, a dehumidifier that generates dehumidified dry air, an air conditioner having a dehumidifying function, or the like can be selected. Further, solid absorbents such as calcium chloride and phosphorus oxide, liquid absorbents such as triethylene glycol and glycerin, silica gel and activated carbon may be used.

[0017]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows a cleaning apparatus according to an embodiment of the present invention.
The cleaning apparatus of the present embodiment is configured by uniting each process including cleaning, rinsing, dehydration, and drying, connecting 10 unitized cleaning units, and connecting a warm air drying unit 12 to the final step. To be done. Here, the cleaning units 2, 3 and 4 are applied to a cleaning process for cleaning an object to be cleaned with an aqueous cleaning liquid, and the cleaning units 5, 6 and 7 are a rinse process for removing the cleaning liquid adhering to the object to be cleaned with pure water. Applied. Further, the cleaning units 8 and 9 are applied to the dehydration step of dehydrating the object to be cleaned after the rinse step by immersing it in the hydrophilic solvent, and IPA is used as the hydrophilic solvent. The cleaning units 10 and 11 are applied to the immersion drying step of removing IPA from the object to be cleaned after the dehydration step. Siloxane is used as the non-aqueous solvent in the cleaning units 10 and 11, and the object to be cleaned after the dehydration step is immersed in siloxane to remove IPA. The warm air drying unit 12 is for drying the object to be cleaned from the immersion drying step, and warm air is supplied to the inside of the unit 12. The control unit 1 is arranged in front of the frontmost cleaning unit 2 to control all the cleaning units.

With respect to such a cleaning apparatus, the object to be cleaned 20 such as a lens, which is set in the cleaning basket 21, is sequentially conveyed to each cleaning unit and subjected to a predetermined process.

In order to carry the cleaning basket 21 in each cleaning unit and transfer the cleaning basket 21 between the cleaning units, each cleaning unit has an endless conveyor 23.
Is equipped with. 24 is a carry-in conveyor for carrying the cleaning basket 21 into the control unit 1, 25 is a warm air drying unit 1
2 is a carry-out conveyer for carrying out the cleaning basket 21 from 2. Further, a partition 26 is arranged between the cleaning units 7 and 8 in the rinse process and the dehydration process to prevent water vapor generated in the process before the rinse process from entering the process after the dehydration process. In addition, the warm air drying unit 12
A partition plate 27 is provided at the entrance and the exit of the unit to shut off the unit 12 from the outside air.

In such a structure, a dehumidifier 30 as dehumidifying means is attached to the downstream cleaning unit 9 of the two cleaning units 8 and 9 applied to the dehydration process. The dehumidifier 30 removes water vapor from the air in the cleaning unit 9.

FIG. 2 is a sectional view of the cleaning unit 9 taken along the line EE, in which a cleaning tank 31 filled with IPA is provided inside a main body 32. The cleaning tank 31 is arranged below the conveyor 23, and an ultrasonic oscillator 33 is attached to the bottom surface thereof. A control box 38 is provided above the cleaning unit 9, and a dehumidifier 30 is provided on the control box 38. Dehumidifier 3
0 is connected to the upper back side of the main body 32 via a connecting pipe 34. The main body 32 corresponding to the connecting portion of the connecting pipe 34
A damping filter 35 that reduces the wind speed of the air that flows in from the connecting pipe 34 is disposed inside, and a partition plate 36 that is a porous plate is disposed adjacent to the damping filter 35. Reference numeral 37 denotes a lid body provided on the front surface of the main body 32 and capable of opening and closing. The dehumidifier 30 is for dehumidifying and generating dry air, for example, 8 L at a humidity of 60%.
A dehumidifier with a trade name of RD-567LA (manufactured by Hitachi, Ltd.) having a dehumidifying capacity for 1 day can be used.

The cleaning unit 9 removes the pure water adhering to the object to be cleaned by immersing the object to be cleaned 20 together with the cleaning basket 21 in the IPA in the cleaning tank 31 and applying ultrasonic vibration. To do. Then, the cleaning basket 21 is pulled up from the cleaning tank 31 to wash the cleaning unit 10 in the immersion drying process.
The object 20 to be cleaned passes through the upper space of the cleaning tank 31 when the cleaning basket 21 is pulled up. At this time, since the upper space is filled with the dry air from the dehumidifier 30, water vapor does not condense, and water droplets do not adhere to the object to be cleaned 20.

FIG. 4 shows the result of cleaning the plastic lens by the cleaning device having the above-mentioned structure. In the figure, the vertical axis represents the absolute humidity in the environment after the object to be cleaned is lifted from the IPA of the cleaning unit 9 and is immersed in siloxane of the cleaning unit 10, and the horizontal axis represents the IPA in the cleaning unit 9.
The liquid temperature was ".largecircle.", And good cleaning results were obtained without the adhesion of water droplets, and ".times." Represents poor cleaning due to residual stains and the like. As shown in the figure, good cleaning becomes possible under the condition that the absolute humidity of the environment is 10 g / m ³ or less.

The dehumidification in the atmosphere described above can be applied not only to the dehydration step but also to the drying step. For example, for the system in which the object to be cleaned is dried in the IPA vapor at about 80 ° C. after the dehydration step by IPA, the atmosphere from the final cleaning unit in the dehydration step to the preceding stage of the drying unit in the drying step is described above. A dehumidifying atmosphere is used, and by carrying the object to be cleaned in this atmosphere, it is possible to prevent cleaning defects such as stains remaining due to water droplet adhesion. By applying to such a system, IP used as steam, which has been performed frequently in the past
The water content control and liquid exchange of A can be extended and used. This is because the amount of water condensed on the surface of the object to be cleaned after the immersion in IPA is significantly reduced. As a result, it is possible to reduce the liquid cost, the number of man-hours required for replacement or liquid management, and the running cost.

In the above embodiment, the hydrophilic solvent I
Although PA was used, the present invention is not limited to this, and methyl alcohol and ethyl alcohol have the same action, and the absolute humidity in the environment is 7.5 for methyl alcohol.
Good cleaning quality is obtained when g / m ³ or less and ethyl alcohol is 8.5 g / m ³ or less.

Although siloxane was used as the non-aqueous solvent in the above examples, the present invention is not limited to this. Freon, methyl chloride, trichloroethylene, 1,
1,1-trichloroethane, perfluorocarbon, and a hydrocarbon solvent also have the same effect.

Further, vapors of the above-mentioned hydrophilic solvent and non-aqueous solvent may be used, whereby the same action can be performed without having a forced drying means such as warm air.
In addition, although a dehumidifier was used as the dehumidifying means, for example,
An air conditioner having a cooling capacity of about 5000 Kcal / h or other dehumidifying means may be used. Also, the object to be cleaned is not limited to the lens, but is also applied to cleaning other parts that require high cleaning quality, such as electric and electronic parts such as printed circuit boards / liquid crystal boards and wafers, mechanical parts, etc. It is possible.

[0028]

INDUSTRIAL APPLICABILITY As described above, according to the present invention, since water droplets are prevented from adhering to the surface of the object to be cleaned, clean cleaning can be performed.

[Brief description of drawings]

FIG. 1 is a partially cutaway front view of a cleaning device according to an embodiment of the present invention.

FIG. 2 is a sectional view taken along line EE of FIG.

FIG. 3 is a characteristic diagram illustrating adhesion of water droplets.

FIG. 4 is a characteristic diagram showing the operation of the embodiment of the present invention.

FIG. 5 is a flowchart of a conventional cleaning method.

[Explanation of symbols]

9 Cleaning unit 20 Cleaning target 30 Dehumidifier

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Claims (7)

(57) [Claims] 1. A predetermined amount of an object to be cleaned is treated with a hydrophilic solvent.
Perform the cleaning process and remove the items to be cleaned in a dehumidified atmosphere.
The process of carrying and performing a predetermined cleaning treatment with a non-aqueous solvent
A cleaning method characterized by being provided. 2. The cleaning method according to claim 1, wherein the dehumidification is performed so that the absolute humidity is 10 g / m ³ or less. 3. The cleaning method according to claim 1, wherein the hydrophilic solvent is isopropyl alcohol, ethyl alcohol or methyl alcohol. 4. The cleaning method according to claim 1, wherein the hydrophilic solvent is isopropyl alcohol, ethyl alcohol, or methyl alcohol in a vapor form. 5. The cleaning method according to claim 1, wherein the non-aqueous solvent is CFC, methylene chloride, trichloroethylene, 1,1,1-trichloroethane, perfluorocarbon, siloxane or a hydrocarbon solvent. Wherein said non-aqueous solvent is chlorofluorocarbon claim, characterized by using methylene chloride, trichlorethylene, 1,1,1-trichloroethane, perfluorocarbons, a siloxane or hydrocarbon solvent in vapor form 1
The described cleaning method. 7. An article to be cleaned, which is filled with a hydrophilic solvent.
A cleaning tank that performs the prescribed cleaning process and a non-aqueous agent are filled.
A cleaning device comprising: a cleaning tank for performing a predetermined cleaning process on an object to be cleaned; and a dehumidifying means for dehumidifying an upper space of a transfer device for transferring the object to be cleaned.