JPH0546256B2 - - Google Patents

Description

[Detailed Description of the Invention] 〓Field of Industrial Application〓 The present invention is applicable to operations that require a dust-free environment while using chemical solutions that generate harmful vapors and gases, such as volatile organic solvents and acids. This relates to the clean draft chamber used in the event.

〓Conventional technology〓 Clean draft chambers are used when cleaning and etching operations using volatile organic solvents and acids need to be performed in a dust-free environment during the manufacturing process of semiconductor products and precision mechanical parts. .
A normal draft chamber equipped only with an exhaust device for discharging harmful gases takes in dusty air around the draft chamber from its working opening, but a clean draft chamber, as shown in Figure 4, A blower 22 with a high-performance air filter 21 is installed on the ceiling to supply clean air from the ceiling to the work space 23, and an exhaust port 25 is provided on or around the work table 24 to force contaminated air out with an exhaust device 29. Since the work space 23 is designed to be discharged, the working space 23 is kept in a cleaner environment with less floating dust than the area around the draft chamber.

When using this clean draft chamber, a high-performance air filter 2 is required to prevent the organic solvent or acid vapor contained in the container 26 from leaking out from the working opening 27 of the chamber.
Amount of clean air supplied via 1 (m ³ /min)
The contaminated air Q ₃ in the chamber in an amount exceeding Q ₁ is exhausted by the exhaust device 25 so that an amount of ambient air Q ₂ equal to Q ₃ −Q ₁ constantly flows into the chamber from the opening 27 at a wind speed v. do. However, the cleanliness inside the chamber decreases as the amount of inflow Q ₂ of ambient air with a lot of suspended dust increases, so it is not preferable to increase the amount too much.
as 0.25m/sec or less, 0.4m/sec or less, or
Limited to 0.5m/sec or less.

When keeping the wind speed v at a predetermined value, the amount of ambient air inflow
Since Q ₂ is proportional to the opening height H, which is variable by the shutter 28 that moves up and down, the higher the opening height H is, the larger the ambient air inflow amount Q ₂ becomes. Therefore, if the opening height H is increased due to work necessity, a large amount of surrounding air-conditioned air will be taken into the draft chamber and discarded, increasing the air conditioning cost of the room where the draft chamber is installed. I will let you do it. In addition, in order to ensure cleanliness inside the chamber while taking in surrounding air, the amount of clean air supplied Q ₁ must be set to a high level, which increases the amount of contaminated air Q ₃ inside the chamber, and the blower 22 Another problem was that the power cost of the exhaust system 29 was high.

〓Problems to be Solved by the Invention〓 The purpose of the present invention is to solve the above-mentioned problems in a clean draft chamber, and to ensure a clean and spacious work space with a small amount of surrounding air intake and low power costs. The purpose is to provide a clean draft chamber.

〓Means to solve the problem〓 A blower with a high-performance air filter is installed on the ceiling to supply clean air to the work space, and an exhaust outlet is installed on or around the work table to remove contaminated air. In a clean draft chamber with forced exhaust air using an exhaust device, an intake port is provided along the front edge of the workbench to serve as the air intake for the blower, and a recess for installing a chemical container is provided in the workbench. An exhaust port is provided in the side wall of the recess, which is communicated with an exhaust device through a duct, and a high-speed air flow flows into the recess across the upper part of the workbench where the recess is not installed. A clean air injection nozzle was installed on the ceiling.

In this clean draft chamber, an exhaust port with a shutter may be provided on the workbench at the back of the recess for installing the chemical solution container.

The recess for installing chemical liquid containers should be large enough to accommodate all the necessary chemical liquid containers with plenty of room. Further, it is desirable that the depth is sufficiently deep so that the entire medical liquid container can be contained therein.

〓Operation〓 When using the clean draft chamber of the present invention, a chemical liquid container containing an organic solvent or an acid necessary for the work is placed in the recess for installing the chemical liquid container, as a general rule.
As a result, contaminated air generated during work does not spread throughout the work space, but instead remains mainly within the recess for installing the chemical solution container. When the exhaust system is operated, this contaminated air enters the duct through the exhaust port on the side wall of the recess.
Discharged outdoors. On the other hand, when the clean air supply blower is operated, relatively clean air inside the chamber near the chamber opening and surrounding air are sucked in through the intake port and filtered by a high-performance air filter.
The clean air flows down from the ceiling toward the workbench. Since most of this clean air is sucked in through the intake port, most of the clean air will be circulated through the above-mentioned path. If a chemical solution container or other source of air contamination is placed on the workbench other than the recess for installing the chemical container, the contaminated air generated on the workbench will be injected into the recess from the clean air injection device. The air is attracted by the incoming high-speed airflow and flows into the recess, joins with the contaminated air generated within the recess, and is discharged outdoors by the exhaust device.

The amount of air injected from the clean air injection nozzle may be negligible compared to the amount of clean air circulated by the blower, so the amount of ambient air inflow from the chamber opening and the inflow wind speed are effectively
It is determined only by the amount of air exhausted from the exhaust port.

〓Example〓 In the example shown in Figs. 1 and 2, the workbench 1 has two recesses 2 for installing chemical liquid containers, and an air intake port along the edge of the opening 3 in front of the recesses 2. 4
and an exhaust port 5 with a shutter provided in the inner part of the recess 2 for installing a chemical liquid container.

The chemical liquid container installation recess 2 is deep enough to completely accommodate the chemical liquid container 6, and has an exhaust port 7 on its side wall.
There is also an exhaust pipe (not shown) connected to the bottom plate (for flushing cleaning water, etc.).

The intake port 4 is formed of a perforated plate formed into a U-shaped groove, and communicates with a blower 10 in the ceiling portion through a duct 9. There is a high-performance air filter 11 under the blower 10, and all the air sent out by the blower 10 passes through this filter 11 and flows down into the work space 12.

Exhaust duct 13 surrounds recess 2 for installing chemical liquid container.
The exhaust port 7 and the shuttered exhaust port 5 communicate with an exhaust device 15 by this duct 13 and an exhaust duct 14 following it.

In addition to the high-performance air filter 11, a clean air injection nozzle 16 is fixed to the ceiling.
is selected so that it traverses the work space 12 above the portion of the workbench 1 where the recess 2 is not present and toward the center of the recess 2 . The nozzle 16 is connected by a pipe 17 to a compressor 19 with a high performance air filter 18.

The opening 3 has a shutter 20 that can move up and down, and by moving this up and down, the effective height H of the opening 3 can be adjusted.

When cleaning, etching, etc. are performed using this draft chamber, the shutter of the shuttered exhaust port 5 is normally closed. Chemical liquid containers such as flat buckets containing organic solvents and acids necessary for work 6
When the blower 10, exhaust device 15, and compressor 19 are operated with the chemical liquid container installed in the recess 2, most of the vapor generated from the solvent and acid in the chemical liquid container 6 will accumulate in the recess 2 during operation. Air contaminated by the air is sucked by the exhaust device 15, enters the exhaust duct 13 from the exhaust port 7 at a total flow rate _Q4 , and is discharged outdoors via the exhaust duct 14, where the solvent and the like are appropriately disposed of. On the other hand, clean air flows down from the high-performance air filter 11 at a flow rate of _Q1 .
Keep the work space 12 clean. A part of the clean air that flows down flows around the chemical solution container 6, becomes the above-mentioned contaminated air, and is discharged from the exhaust port 7 at a total flow rate of _Q4 .
Most of the air (Q ₁ - _{Q 4} ) is sucked in through the intake port 4 without being contaminated by the chemical vapor, enters the duct 9, is filtered by the high-performance air filter 11, becomes clean air again, and enters the work space 12. Enter the circular path of entering. Furthermore, since the clean air jet stream directed from the nozzle 16 toward the recess 2 attracts the air on the workbench 1 into the recess 2, the source of air contamination of the chemical solution 6' is placed on the workbench 1 (the part without the recess 2). Most of the contaminated air generated in this case flows into the recess 2 and is discharged outdoors together with the contaminated air generated within the recess 2 via the exhaust port 7, the exhaust duct 13, and the exhaust duct 14. This prevents the contaminated air generated on the workbench 1 from flowing into the intake port 4 and contaminating the circulating air flow.

The amount of air jetted from the nozzle 16 is very small compared to the amount of air blown by the blower 10. and,
Since there is no intake port for the blower 10 other than the intake port 4, the amount of air discharged as contaminated air Q ₄
A quantity Q ₂ of ambient air substantially equal to Q 2 is drawn in through the air inlet 4 . The amount of incoming air Q ₂ is not affected by changes in the opening height H caused by operating the shutter 16. This surrounding air is dusty air, but since the air curtain-like clean air flow concentrated from the high-performance air filter 11 toward the intake port 4 acts as a barrier film, it enters the chamber before entering the intake port 4. This prevents the work space 2 from being contaminated with floating dust.

If the work is to be suspended while the blower 10 etc. are being operated, it is recommended to cover the recess 2 for installing the chemical liquid container with a suitable perforated lid to prevent the diffusion of chemical liquid vapor, and open the shutter of the exhaust port 5 with a shutter. This further reduces the leakage of the chemical vapor, and on the other hand, the exhaust device 15 continues to discharge air at a flow rate _Q4 via the exhaust port 5, thus maintaining a stable air volume balance. Flow rate Q ₄ without providing exhaust port 5 with shutter
The minimum number of ventilation holes necessary for evacuation may be provided in the lid of the recess 2 for installing the chemical solution container.

〓Effects of the Invention〓 Based on the above-described configuration, the clean draft chamber of the present invention minimizes the diffusion of the chemical vapor used and quickly exhausts only a small amount of heavily contaminated air from the site where it is generated to the outdoors. Therefore, the leakage of contaminated air can be suppressed with a much smaller exhaust volume than that required in a conventional clean draft chamber that suctions and discards the entire amount of air inside the chamber. Therefore, the clean draft chamber of the present invention has the following advantages, compared to conventional clean draft chambers that require a large amount of ambient air to flow in through the opening and a large amount of clean air to prevent the spread of contaminated air. It has the advantage of not consuming a large amount of conditioned air in the room where the draft chamber is installed and significantly increasing air conditioning costs, and that the power costs for the blower and exhaust device are low. In addition, the dusty surrounding air that is taken into the air supply system in an amount commensurate with the amount of outdoor emissions is blocked by the air curtain-like clean air flow from the high-performance air filter toward the intake port, and does not enter the chamber. Since it enters the air intake directly, there is no risk of introducing floating dust into the chamber. Furthermore, since most of the clean air is recycled and reused, the high-performance air filter lasts a long time.

Furthermore, by ejecting air from the ceiling toward the recess, contaminated air generated on the workbench other than the recess is also guided to the recess and discharged, so that work can be carried out without worrying about increasing the degree of contamination of the circulating air. Depending on the situation, either the inside of the recess or the top of the workbench can be used.

As described above, the clean draft chamber of the present invention is extremely advantageous in that it can stably realize a clean working environment at a much lower cost than the conventional one.

[Brief explanation of the drawing]

1 and 2 are schematic vertical sectional views of an embodiment of the present invention, with FIG. 1 being a front view and FIG. 2 being a side view. FIG. 3 is a plan view of the workbench 1 in the above embodiment, and FIG. 4 is a schematic longitudinal sectional view showing an example of a conventional clean draft chamber. 1, 24...Workbench, 2...Recess for installing chemical solution container, 3, 27...Opening, 4...Intake port, 5,
7, 25...exhaust port, 6,26...chemical container,
9,13...Duct, 10,22...Blower, 1
1, 18, 21...High performance air filter, 1
2, 23... Working space, 15, 25... Exhaust system, 16... Nozzle, 19... Compressor,
20... Shutter.

Claims (1)

[Claims] 1 A blower with a high-performance air filter is installed on the ceiling to supply clean air to the work space, and an exhaust port is installed on or around the work table to forcefully exhaust contaminated air using the exhaust system. In the clean draft chamber, an air inlet is provided along the front edge of the workbench, which serves as an air intake for the blower, and a recess for installing a chemical solution container is provided in the workbench, and the side wall of the recess is provided with an inlet. A clean air injection nozzle is installed in the ceiling to create a high-velocity air flow that crosses over the part of the workbench where the recess is not installed and flows into the recess. A clean draft chamber characterized by being installed in the section.