JP3505035B2 - 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 washing electronic parts such as a printed wiring board with water, and particularly to a method of cleaning an object to be cleaned which has been subjected to an acid cleaning treatment or an alkali cleaning treatment as a pre-process of the cleaning treatment. When washing with tap water or water with a relatively low purity of industrial water class as a process, it is suitable for saving the supply of tap water and stabilizing the water quality by always maintaining the purity of the wash water at a certain level. A cleaning method and an apparatus therefor.

[0002]

2. Description of the Related Art Conventionally, as a water supply control method for cleaning while maintaining and managing the purity of cleaning water at a constant level, for example, a cleaning apparatus having a structure shown in FIG. . This device is used for controlling ultrapure water for semiconductor wafer production, and as shown in the figure, the flow of the work (the object to be cleaned) 16 and the flow of cleaning water are in opposite directions. The first washing tank 4, the second washing tank 5, and the third washing tank 6 are provided from the upstream in the flow direction of the work. The plurality of water washing tanks are continuously connected, and the washing water overflows from the downstream side in the flow direction of the work, which is a multi-stage countercurrent type. Third washing tank 6
Is provided with ultrapure water supply means for supplying wash water and a resistivity meter for measuring the resistivity of wash water. In this case, the control value of the resistivity meter is several tens of MΩcm, and the control value is 10,000 times larger than that of tap water or industrial water of several kΩcm.

Further, as a water cleaning apparatus using tap water, for example, as disclosed in Japanese Patent Laid-Open No. 59-228988, a sensor for detecting the electric conductivity of water in a water washing tank and the detected electric conductivity. There is known a cleaning device in which a control panel for controlling ON / OFF of tap water supply depending on the temperature and an electromagnetic valve are attached to make the electric conductivity of water in the cleaning tank always constant.

[0004]

In the case of the former apparatus for cleaning with ultrapure water, the specific resistance value of tap water or industrial water, which is the object of the present invention, is about 10,000 times larger,
Extremely high precision instruments are required, and no consideration is given to the effective use of wash water as a water resource. Further, in the latter case, the supply of tap water is controlled to be turned on and off by the electric conductivity, but no consideration is given to effective use of water resources such as purification of wash water and recycling.

Therefore, an object of the present invention is to solve the above-mentioned problems of the prior art, and to control the water supply amount of cleaning water having a purity of tap water level to always properly manage the water quality and to use the used cleaning water. An object of the present invention is to provide an improved cleaning method and an apparatus therefor which can regenerate water and effectively utilize water resources.

[0006]

According to the cleaning method of the present invention which can achieve this object, a plurality of washing tanks are continuously provided, and the washing water overflows sequentially from the downstream side in the moving direction of the object to be washed. Using the coming multi-stage countercurrent type washing device, and wash with tap water as washing water or washing water of water quality of industrial water level, recycle and purify the topmost dirty washing water with a reverse osmosis membrane, A cleaning method comprising a cleaning water purification and recycling circuit for circulating and reusing this in the most downstream washing tank, and measuring the specific resistance of the most downstream washing tank,
Based on the obtained specific resistance value, the degree of contamination of the wash water in the wash tank is judged, and the amount of wash water supplied is controlled so that the concentration of impurities in the wash water is always within a predetermined control range. The specific resistance of the circulating water before and after the reverse osmosis membrane in the regeneration circuit is measured to determine the regeneration treatment capacity of the reverse osmosis membrane.

When the specific resistance value of the cleaning water in the cleaning tank is measured and the amount of cleaning water supplied is controlled so that the impurity concentration is within a predetermined control range, a specific resistance value as a standard of water quality is used. Controlled in comparison with, the tap water used in the present invention, or the water quality of industrial water has a specific resistance value of 1.0 to 4.5 kΩcm. The specific resistance value is managed so as to satisfy the above condition, and the supply amount of fresh wash water is controlled based on this.

Further, in the cleaning apparatus of the present invention which can achieve the above object, a plurality of washing tanks are continuously provided,
This is a multi-stage countercurrent type washing device in which washing water sequentially overflows from the downstream side in the moving direction of the item to be washed. Is measured to determine the degree of fouling, and the water supply means that controls the amount of wash water supplied so that the concentration of impurities in the wash water is always within the prescribed control range, and the most upstream dirty wash water is provided by the reverse osmosis membrane. The cleaning water is provided with a cleaning and recycling means for cleaning and purifying and circulating it to the most downstream water washing tank for reuse, and the cleaning and water recycling means has a ratio of circulating water before and after the reverse osmosis membrane. It is configured by arranging means for measuring the resistance and determining the regeneration processing capacity of the reverse osmosis membrane.

A partition plate is disposed in the most downstream washing tank in which the resistivity meter is disposed, near the partition wall of the adjacent washing tank with a predetermined gap from the partition wall, and the partition plate is provided in this gap. It is desirable to provide a sensor section. Then, at the lower end of this partition plate, a gap is formed between the bottom of the washing tank and the bottom of the washing tank, the upper end of which is projected from the water surface so that the washing water directly flows into the adjacent washing tank. It is desirable to shut off so that it does not happen.

Further, the water supply means for measuring the specific resistance value of the cleaning water in the cleaning tank and controlling the supply amount of the cleaning water so that the impurity concentration is within a predetermined control range has a specific resistance value of a constant level. It is desirable that the water supply means is provided with a control means for opening and closing the solenoid valve of the water supply pipe at the stage when it has reached, so that the solenoid valve of the water supply pipe can be automatically opened and closed to properly manage the water quality at all times.

As means for measuring the specific resistance of the circulating water before and after the reverse osmosis membrane to determine the regeneration treatment capacity of the reverse osmosis membrane, a resistivity meter is provided before and after the reverse osmosis membrane, respectively. It is desirable to provide means for regenerating or replacing the reverse osmosis membrane when the output difference becomes less than a predetermined reference value.

[0012]

1 is a block diagram showing an embodiment of the present invention.
~ It demonstrates using FIG. FIG. 1 shows a schematic cross-sectional view of a cleaning apparatus having a cleaning water supply control means and cleaning water purification regeneration circulation means. FIG. 2 is a characteristic diagram showing the relationship between the impurity concentration of the wash water and the specific resistance value in the case of pure water and tap water.

First, an example of the structure of the cleaning device will be described with reference to FIG. The first washing tank 4, the second washing tank 5, and the third washing tank 6 share a partition wall from the upstream of the flow direction 10 of the work 16 and are sequentially connected. Third washing tank 6
The resistivity meter 1 for measuring the resistivity of the wash water is a partition plate 9 _-3.
It is provided in the lower region of the space constituted by the partition.

A tap water pipe 11 for replenishing wash water is provided above the third water washing tank 6, and the tap water pipe 11 has
A tap water solenoid valve 12 is provided. Further, a flush water drain pipe 13 is provided above the first flush tank, and a drain solenoid valve 14 is provided in the flush water drain pipe 13.

Further, between the first washing tank 4 and the third washing tank 6, there is provided a washing water circulation pipe 15 for circulating the washing water from the lower portion of the first washing tank 4 to the upper portion of the third washing tank 6. A circulation pump 7 and a reverse osmosis membrane 8 are provided in the wash water circulation pipe 15, and specific resistance meters 2 and 3 for measuring the specific resistance are provided in front of and behind the reverse osmosis membrane 8 to purify and recycle the wash water. Are configured.

Partition plates 9 _-1 to ₃ are provided near the upstream tanks of the water washing tanks 4 to 6 at predetermined intervals from the partition walls.
The lower end portions of these partition plates form a flow path with a predetermined gap from the tank bottom portion, and the upper end portions are projected from the liquid surface so that washing water does not overflow from the partition plate. However, only the partition plate _9-0 of the first washing tank 4 has a configuration opposite _to that of the other partition plates 9 ₁ to ₃ , the lower end portion is connected to the tank bottom portion to block the flow path, and the upper end portion is the liquid. The cleaning water overflows from the partition plate in contact with the surface.

In this washing apparatus, a plurality of washing tanks of the washing apparatus are continuously connected, and the washing water is of a multi-stage countercurrent type in which the washing water overflows from the downstream side in the flow direction 10 of the work 16.

Next, the cleaning mechanism of the apparatus will be described together with its operation. When cleaning the work 16, the washing water is supplied to the third washing tank 6, and the washing water overflowing from the third washing tank 6 is washed with the second washing tank 6. The washing water that has entered the tank 5 and has overflowed from the second washing tank 5 enters the first washing tank 4 to wash the work 16. The washing water in the washing tank is as clean as downstream, and the upstream first washing tank 4 is the most dirty.
6 is washed, then washed in the second washing tank 5, and finally washed with clean washing water in the third washing tank 6. Third
The resistivity meter 1 provided in the washing tank 6 measures the resistivity of the washing water and monitors the purity of the washing water.

Here, the relationship between the impurity concentration of the wash water and the specific resistance value will be described with reference to FIG. As indicated by the alternate long and short dash line in the figure, when impurities are added to pure water, the specific resistance value decreases linearly. However, when impurities are added to tap water, the resistivity value decreases linearly from the place where the concentration of impurities in the wash water is high to some extent as shown by the solid line. Therefore, no matter how low the impurity concentration is, the value of the specific resistance of tap water does not become higher than a certain value like pure water.

However, in a cleaning apparatus for cleaning water such as semiconductor wafers using tap water without cleaning with ultrapure water, for example, when the cleaning water purity control width d is set as shown in FIG. The resistance value may be controlled between 3.2 and 1.9 kΩcm.

Although it is desirable to set the control width d of the cleaning water purity to the width as in this example, as is apparent from FIG. 2, the level of the specific resistance of tap water is about 4.5 kΩcm, The specific resistance allowed as wash water is 1.0 kΩcm
From the above, the management width is usually 1.0 to 4.5k.
It may be in the range of Ωcm.

In this way, the washing water in the third washing tank 6 is
It is constantly monitored by the resistivity meter 1 within the above-mentioned predetermined control width d,
The amount of water supply is controlled. When the measured value of the resistivity meter 1 deviates from the resistivity value corresponding to the control width d of the wash water concentration, the tap water solenoid valve 12 is opened to supply tap water. Also, when tap water is supplied, the drainage solenoid valve 14 is opened at the same time,
Rinse water corresponding to the supplied amount of tap water is drained from the drainage pipe 13 to the outside. With this drainage, impurities in the water wash can be removed from the water wash tank to the outside.

When the tap water is continuously supplied and the measured value of the resistivity meter 1 deviates from the resistivity value corresponding to the control width d of the wash water concentration, the tap water solenoid valve 12 and the drainage solenoid valve 14 are closed. Stop the tap water supply. As a result, the work 16 is always cleaned with the specified purity without wasting tap water.

As described above, during the period in which the measured value of the resistivity meter 1 is within the control range d of the wash water concentration and the tap water solenoid valve 12 and the drain solenoid valve 14 are closed to stop the supply of tap water. In the cleaning, the purifying and recycling circulation means of the cleaning water is operated as described below to effectively use the water resource.

That is, the rinsing water overflowing from the partition plate _9-0 of the first rinsing tank 4 circulates from the lower part of the space (drain region) formed by the partition plate _9-0 and the wall surface of the rinsing tank 4. It is circulated by the pump 7, purified through the reverse osmosis membrane 8, and supplied to the third washing tank 6 for recycling. At this time, the water quality before and after passing through the reverse osmosis membrane 8 is measured by the specific resistance meters 2 and 3 to monitor the qualitative water-producing ability of the wash water to control the life of the membrane. Specifically, the specific resistance value of the washing water before passing through the membrane should be lower than the specific resistance value of the washing water after passing through the membrane.
It can be seen that the life of the film is reached when the measured values of the two resistivity meters show close values. As a result, the life of the reverse osmosis membrane can be easily controlled, and the amount of water supplied can be controlled so that the water quality can be stably maintained and washing can be performed without wasting water resources.

Such a cleaning water purifying / regenerating and circulating means is
The operation may be performed not only during the period in which the supply of tap water is stopped, but also in parallel with the water supply by opening the solenoid valve 12. In that case, the electromagnetic valve 12 may be controlled to limit the amount of tap water supplied, and a part of this may be supplemented with this recycled purified water.

For such water supply control of wash water, the output of the resistivity meter 3 and the output of the resistivity meter 1 are input to a differential amplifier, and when the outputs exceed a certain level, the solenoid valve 12 is operated.
Can be operated to automatically perform water supply control.

As described above, by measuring the specific resistance before and after the reverse osmosis membrane 8 to control the life of the reverse osmosis membrane, the water quality of the wash water is always kept stable, and the wash water is washed with a minimum amount of water. You can now do.

[0029]

EXAMPLES The following describes the cleaning of the printed circuit board after the plating process with water using the cleaning apparatus shown in FIG. As the reverse osmosis membrane 8, a spiral type element using a crosslinked wholly aromatic polyamide composite membrane was used. The solute removal rate by the reverse osmosis membrane 8 used here is about 95%. The washing water in the first washing tank 4 has a concentration about 300 times that of the third washing tank 6.

The cleaning water which has been purified and regenerated by operating the purification and recirculation means is circulated in the third washing tank 6 and the solenoid valve 12
Was opened to replenish tap water, and washing was continued while maintaining stable water quality. As a result, the amount of tap water supplied to the third washing tank 6 could be reduced by about 15%.

Some reverse osmosis membranes 8 are of high quality and have a solute removal rate of about 99% or more. If this type of water is used, the reduction rate of tap water is 50% or more, and in some cases, it is possible to wash with only purified and regenerated circulating water.

[0032]

As described above in detail, according to the present invention, the intended purpose can be achieved. That is, by measuring the specific resistance of the wash water with a purity of tap water level, controlling the amount of water supplied to control the quality of the wash water, and purifying the wash water by the reverse osmosis membrane, the purification and recycling circulation means for the wash water is used. The water resources can be used effectively. In addition, by measuring the specific resistance before and after the reverse osmosis membrane and managing the life of the reverse osmosis membrane, the water supply amount is controlled and the water quality is kept stable without wasting water, and at the same time the reverse osmosis membrane Lifespan can be easily managed.

[Brief description of drawings]

FIG. 1 is a schematic cross-sectional view of a cleaning device according to an embodiment of the present invention.

FIG. 2 is a characteristic diagram showing the relationship between the impurity concentration of wash water and the specific resistance value in the case of pure water and tap water.

FIG. 3 is a schematic cross-sectional view of a conventional cleaning device.

[Explanation of symbols]

1, 2, 3 ... Resistivity meter, 4 ... the first flush tank, 5 ... second washing tank, 6 ... third washing tank, 7 ... Circulation pump, 8 ... Reverse osmosis membrane, 9 ... Partition board, 10 ... Work flow direction, 11 ... Tap water piping, 12 ... Tap water solenoid valve, 13 ... Washing water drainage pipe, 14 ... Drainage solenoid valve, 15 ... Washing water circulation piping, 16 ... Work.

─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Iku Fujiwara 216 Totsuka-cho, Totsuka-ku, Yokohama-shi, Kanagawa Hitachi, Ltd. Information & Communication Division (56) Reference JP-A-7-100444 (JP, A) (58) ) Fields surveyed (Int.Cl. ⁷ , DB name) C23G 1/36 B08B 3/14 C25D 21/20 H05K 3/26

Claims (7)

(57) [Claims] 1. A multistage countercurrent type washing device in which a plurality of washing tanks are continuously provided, and washing water overflows sequentially from the downstream side in the moving direction of the article to be washed, and tap water is used as the washing water. Washing with water or wash water of water quality of industrial water level, recycle and purify the dirty water at the uppermost stream with a reverse osmosis membrane, and circulate this in the water washing tank at the most downstream and reuse it A cleaning method comprising a circulation path, wherein the specific resistance of the above-mentioned downstreammost washing tank is measured, and the obtained specific resistance value is used to judge the degree of contamination of the washing water in the washing tank to always wash. The amount of wash water supplied is controlled so that the concentration of impurities in the water is within a predetermined control range, and the specific resistance of the circulating water before and after the reverse osmosis membrane in the purification regeneration circuit is measured to regenerate the reverse osmosis membrane. A cleaning method configured to determine throughput. 2. When measuring the specific resistance value of the washing water in the washing tank and controlling the supply amount of the washing water so that the impurity concentration is within a predetermined control range, the specific resistance value is at least 1.0 kΩc.
The cleaning method according to claim 1, wherein the amount of cleaning water supplied is controlled based on the specific resistance value so as to satisfy the condition of m or more. 3. A multi-stage countercurrent type washing apparatus in which a plurality of washing tanks are continuously provided, and washing water overflows sequentially from the downstream side in the moving direction of the object to be washed, which is the most downstream washing tank. Is equipped with a resistivity meter to measure the specific resistance of the wash water to judge the degree of contamination and constantly control the amount of wash water supplied so that the concentration of impurities in the wash water is within a predetermined control range. The water supply means and the cleaning water purifying and recycling circulation means for regenerating and purifying the dirty most upstream cleaning water by the reverse osmosis membrane, and circulating and reusing this in the most downstream washing tank, and the cleaning water A cleaning device in which a means for measuring the specific resistance of the circulating water before and after the reverse osmosis membrane to determine the regeneration treatment capacity of the reverse osmosis membrane is provided in the purification regeneration circulation means. 4. A partition plate is disposed in the most downstream washing tank in which the resistivity meter is disposed, near the partition of the adjacent washing tank with a predetermined gap from the partition, and the specific resistance is provided in this gap. The cleaning device according to claim 3, wherein a sensor portion of the meter is provided. 5. A water supply means for measuring the specific resistance value of the cleaning water in the cleaning tank and controlling the supply amount of the cleaning water so that the impurity concentration is within a predetermined control range, the specific resistance value being kept at a constant level. 4. The cleaning device according to claim 3, wherein the cleaning device comprises a water supply means having a control means for opening and closing an electromagnetic valve of the water supply pipe at the stage when it reaches. 6. A water supply means for measuring the specific resistance value of the cleaning water in the cleaning tank and controlling the supply amount of the cleaning water so that the impurity concentration is within a predetermined control range, the specific resistance value is at least 1. 0k
4. The cleaning device according to claim 3, wherein the cleaning device comprises water supply means for automatically controlling the supply amount of cleaning water based on a specific resistance value as a reference so as to satisfy the condition of Ωcm or more. 7. Means for measuring the specific resistance of the circulating water before and after the reverse osmosis membrane to determine the regeneration treatment capacity of the reverse osmosis membrane, and further respectively disposing specific resistance meters before and after the reverse osmosis membrane. 4. The cleaning device according to claim 3, further comprising means for regenerating or replacing the reverse osmosis membrane when the difference between these outputs falls below a predetermined reference value.