JPH0470054B2 - - 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 creed draft chamber used in the event.

〓Conventional technology〓 In the manufacturing process of semiconductor products and precision mechanical parts, 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. .
A normal draft chamber equipped only with an exhaust device for discharging harmful gases takes in dusty air around the draft chamber through its working opening, but a clean draft chamber, as shown in Figure 3, 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 26. Since the air is 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 inside the chamber in an amount Q ₃ exceeding Q ₁ is exhausted by the exhaust device 25, so that the surrounding air in an amount Q ₂ equal to Q ₃ - Q ₁ always flows into the chamber through the opening 27 at a wind speed v. do. However, the greater the inflow amount _Q2 of ambient air with a lot of suspended dust, the lower the cleanliness inside the chamber, so it is not preferable to increase the amount too much. , 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, Q ₂ increases as the opening height H becomes higher. 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 the cleanliness inside the chamber while taking in ambient air, the clean air supply amount Q ₁ must be set to a high level, so Q ₃ also increases, and the blower 22 and exhaust device 25 The problem was that the power costs were high.

<Problems to be Solved by the Invention> An object of the present invention is to solve the above-mentioned problems in 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 from the ceiling 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 in which air is forcibly discharged by an exhaust installation, an intake port is provided along the front edge of the workbench and this is used as an air intake port for the blower,
A recess for installing a chemical liquid container was provided in the workbench, and an exhaust port was provided in the side wall of the recess, and this was communicated with an exhaust device through a duct.

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

The recess for installing chemical solution containers should be large enough to accommodate all the necessary solution containers with plenty of room.
Further, it is desirable that the depth is deep enough to accommodate the entire solution container.

〓Operation〓 When using the green 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 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 and is discharged outdoors. On the other hand, when the blower for supplying clean air is operated, relatively clean air inside the chamber near the chamber opening and surrounding air are sucked in through the intake port, filtered by a high-performance air filter, and converted into clean air that can be used from the ceiling. Flows down toward the platform. 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. The amount of ambient air flowing in and the speed of the incoming air from the chamber opening are determined only by the amount of air being discharged 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 at the inner part of the recess 2 for installing a chemical solution 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.
A drain pipe (for flushing water, etc.) (not shown) is connected to the bottom plate.

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.

The effective height H of the opening 3 can be adjusted by a shutter 16 that moves up and down.

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 and the exhaust device 15 are operated with the chemical liquid container placed in the recess 2, most of the vapor generated from the solvent and acid in the chemical liquid container 6 during operation will accumulate in the recess 2, resulting in contamination. 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 then flows into the exhaust duct 14.
The solvent is discharged out of the working space via the solvent, and the solvent and the like are disposed of as appropriate. On the other hand, clean air flows down from the high-performance air filter 11 at a flow rate Q ₁ to 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 , but the majority ( _Q1 -
_Q4 ) 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, and enters the work space 12 again as clean air. enter. Since there is no intake port for the blower 10 other than the intake port 4, an amount Q ₂ of ambient air is sucked in from the intake port ₄ , which is equal to the amount of air Q 4 discharged as contaminated air. The amount of incoming air Q ₂ is the shutter 16
It is not affected by changes in the aperture height H due to the investigation. 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 and the exhaust device 14 are in operation, it is preferable to cover the recess 2 for installing the arrow liquid container with a suitable perforated lid to prevent the diffusion of chemical vapor, and to open the shutter-equipped exhaust port 5. 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. The exhaust port 5 with a shutter may not be provided, and the minimum number of ventilation holes necessary for exhausting the flow rate _Q4 may be provided in the lid of the recess 2 for installing the chemical liquid 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 contaminated air from the site where it is generated to the outdoors. Therefore, 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 the conventional clean draft chamber, which required a large amount of ambient air to flow in through the opening and a large amount of clean air to flow in order 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 ambient 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.

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]

FIG. 1 is a schematic vertical cross-sectional view of an embodiment of the present invention, FIG. 2 is a plan view of the workbench 1 in the embodiment of FIG. 1, and FIG. 3 is a schematic vertical cross-sectional view of an example of a conventional clean draft chamber. It is a diagram. 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
1,21...High performance air filter, 12,2
3... Working space, 15, 25... Exhaust device.

Claims (1)

[Claims] 1. In a clean draft chamber in which a blower with a high-performance air filter is installed outside the work space and a clean air flow path is provided to supply clean air into the work space, a chemical solution container is installed on the work table. 1. A clean draft chamber characterized in that a recess is provided, an exhaust port is provided in a side wall of the recess, and the exhaust port is communicated with an exhaust device through a duct. 2 A blower with a high-performance air filter is installed on the ceiling to supply clean air from the ceiling 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 draft chamber characterized in that an exhaust port is provided in the chamber and the exhaust port is connected to an exhaust device through a duct. 3. The clean draft chamber according to claim 1, wherein the workbench is provided with an exhaust port with a shutter at a portion deeper than the recess for installing the chemical solution container.