JPH0461251B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a mobile clean-dry bench that allows various operations to be performed in a clean and dry atmosphere.

[Conventional technology]

Clean rooms have recently been greatly developed in the semiconductor manufacturing industry, electronic equipment, precision equipment, pharmaceutical manufacturing industries, and various research and experiment facilities. Clean benches, thermal multi-chambers, clean dry chambers, dehumidifying clean benches, etc. were used as air processing equipment to create clean spaces for use in clean rooms, and these were installed in clean rooms depending on the purpose. There are various types of these devices, such as those that blow out clean air, those that have a function to adjust the blowing temperature, and those that have a function to adjust the humidity.Generally speaking, benches can be installed in any location and are easy to use. It is similar to a stand, and is also called a chamber, which is fixed in a fixed place to form a closed space, into which air whose temperature and humidity are separately controlled is supplied from outside the chamber through a separate system. I can say it.

However, until now, there have been no clean benches that can be moved and installed in any location, and that have the ability to adjust both temperature and humidity.In particular, humidity is dependent on the humidity conditions within the clean room. It was hot. Therefore, when humidity is particularly important, chambers that form a closed space (supplying dry air from outside the system) have been used, but such chambers were originally used for product storage or temporary storage. Because it was intended to function as a storage space, it was not convenient to use as a workbench, and it was not able to respond quickly to changes in work or layout.

[Problem that the invention seeks to solve]

Therefore, the present invention aims to solve the problems of conventional work in a clean room, and particularly to provide a clean dry bench in which the clean bench has temperature and humidity adjustment functions. In this case, a particular problem is that dry air with a dew point temperature of 4℃ or less, for example, a dew point temperature of -10 to -20℃, is transported to a movable bench that is isolated from the surrounding clean room atmosphere. The question is how to easily obtain it. Although this is easily achieved through the use of chemical hygroscopic agents, this poses the problem of contamination due to hygroscopic agent carryover. In addition, if you try to obtain air with a low dew point temperature by using a so-called cooling dehumidification method that forcibly cools the air and condenses the moisture in the air, this condensation will generate frost, which will reduce functionality. This is accompanied by the problem of water droplet carryover. The present invention attempts to solve these problems.

[Means for solving problems]

As shown in the embodiment of the drawings, the present invention forms a working space 2 and an air circulation path 3 in a movable casing body 1, and the air circulation path 3 has a working space 2 and an air circulation path 3.
In a clean bench equipped with a HEPA filter 4 and blowing clean air from the HEPA filter 4 toward the work space 2,
An air heater 5 is installed in the air circulation path 3 upstream of the HEPA filter 4, and the air circulation path 3 upstream of the air heater 5 is branched into a plurality of air passages, and an air cooler 6 is installed in each passage. The purpose of the present invention is to provide a clean dry bench characterized in that the plurality of air coolers 6 are installed and operated in a switching manner to obtain dry air with a dew point temperature of 4° C. or less, and thereby the above-mentioned This is an attempt to solve the problem of.

The structure and operation of the clean dry bench of the present invention will be specifically explained below according to the embodiments shown in the drawings.

FIG. 1 shows the front appearance of the casing body 1, and FIG. 2 shows the arrangement of internal devices of the casing body 1 from the side. This casing body 1 is movable with casters 7 on the bottom surface. A workbench 8 made of a punching board is installed horizontally inside the casing body 1, the top of this workbench 8 serves as a workspace 2, and a work opening 9 is provided in the front of the casing body 1 facing this workspace 2. is formed. A shutter 10 for opening and closing this working opening 9 is attached. This shutter 10 is made of a transparent plate made of, for example, acrylic resin, and by moving it up and down, the opening degree of the working opening 9 can be freely adjusted.

As seen in the side view of FIG. 2, an air circulation path 3 is formed from the bottom of the workbench 8 to the back of the workspace 2. This air circulation path 3 is a path that extends from the space below the punching board forming the workbench 8, through a hollow portion formed on the back side of the workspace 2, to the ceiling of the workspace 2, and the air blower 11.
By installing this in this passage, work space 2
An air circulation path is formed in which part or all of the air that has been blown out is blown out into the work space 2 again. A high-performance filter (called a HEPA filter) 4 is installed in this air circulation path 3.
In this way, clean air is obtained, and this HEPA filter 4 is horizontally stretched across almost the entire ceiling of the work space 2, and air is blown out from this HEPA filter 4 into the work space 2 as a vertical laminar flow. It is becoming more and more common. And this HEPA
An air heater 5 and an air cooler 6 are disposed in the air circulation path 3 upstream of the filter 4. The air cooler 6 is installed upstream of the air heater 5. Although it is not visible in the figure, the air circulation path 3 is located upstream of the air cooler 6 and downstream of the workbench 8.
An air intake port for taking in air from the outside of the casing body 1 is provided in the casing body 1 (see 1 in Fig. 3 below).
6). In this way, a working space 2 and an air circulation path 3 are formed inside the casing body 1 above the partition plate 12 as a boundary. In the lower space of the casing body 1, equipment such as a refrigerator 13 and a condenser 14 are housed. Further, connection terminals 15 for hot water, cooling water, drain, etc. are provided at appropriate locations on the outer wall of the casing body 1.
The refrigerator and other devices are made into a unit and placed outside the casing body 1.
By integrally connecting the two, it is also possible to make them movable as one.

FIG. 3 schematically shows the circulating air flow system of a clean dry bench according to the present invention. As seen in this figure, the air circulation path 3 on the upstream side of the air heater 5 (downstream from the workbench 8) is branched into a plurality of (two in the figure) air passages A and air passages B. Air coolers 6a and 6b are disposed at. That is, in the air circulation path 3 downstream of the workbench 8 and upstream of the air heater 5, a branching point 17 that branches into the air path A and the air path B.
A merging point 18 is provided for merging the air passage A and the air passage B, and air coolers 6a and 6 are connected to the air passage A and the air passage B arranged in parallel in this way.
b, and the switching dampers 20a and 20b are attached. With this configuration, the switching damper 20a
and 20b, the air coolers 6a and 6b
Circulating air can be selectively supplied to the In addition, in FIG. 3, a precooler 22 is arranged upstream of the branch point 17. These arrangements are actually formed below the air heater 5 in the cavity at the rear of the working space 2 in FIG. Further, when switching between the switching dampers 20a and 20b, the flow of cooling liquid to the air coolers 6a and 6b is also switched, and this control will be described later.

FIG. 4 shows the same circulating air switching system as in FIG. 3 except that defrosting operation is enabled. In the case of FIG. 4, air intake ports 16a take air into each air passage A and air passage B from outside the bench.
and 16b are provided, and exhaust fans 22a and 22 are provided.
The damper 2 is provided with exhaust ports 23a and 23b having
4a, 24b and dampers 25a, 25b, when one air passage is dehumidifying, the exhaust fan is driven in the other air passage to actively remove frost that has adhered to the surface of the air cooler 6. This allows for defrosting operation that removes frost.
Therefore, in this case, it is possible to shorten the start-up time until the state of use is reached after switching.

FIGS. 5 to 7 schematically show various embodiments when an electric heater is used as the air heater 5 and a cold source is supplied from a refrigerator to the air cooler 6. It is designed to obtain dry air with a dew point temperature of about -10 to -20℃, but the fifth
The figure shows a method in which air is heated using only an electric heater, Figure 6 shows a method in which heat from a pre-cooler condenser is used for heating, and Figure 7 shows a method in which the brine from a refrigerator is used as a cold source. .
These will be explained below.

In the embodiment of FIG. 5, the air heater 5 using an electric heater controls the supply air temperature by a thyristor control 27. The air coolers 6a and 6b of each system A and B, and the precooler 22 are cooling coils (evaporators) that supply cold sources from independently installed refrigerators.
use. Therefore, a total of three refrigerators will be installed, but these will be separated into units.
This refrigerator unit 13 may be housed in the lower space of the casing body 1 shown in FIG. 2, but it may also be brought out and connected to the outside of the casing body 1. 28a, 28b shown in this refrigerator unit 13,
28p is the power unit of the refrigerator, and in the case of a compression refrigerator, it is the compressor, and 29a, 29b, 29
p is a condenser, through which cooling water is passed from outside the system. Also, 30a, 30b, 30p
indicates bloated stool. Here, precooler 22
is installed for the purpose of recommending the cooling load of the air coolers 6a and 6b and reducing frost formation.
It is optional whether or not to install this precooler 22, but if it is installed, it functions to maintain the condition of the outlet air of this precooler 22 at a dew point temperature of about 4°C.

The embodiment shown in FIG. 6 has substantially the same configuration as the embodiment shown in FIG. 5, except that the condenser 29p of the precooler 22 is used as an auxiliary heat source for air heating. That is, as the cooling medium for the condenser 29p of the precooler 22, air cooled by passing through the air coolers 6a and 6b is used instead of the cooling water in the case of FIG. This is intended to reduce the load on the heater 5. Therefore, as the condenser 29p of the precooler 22, an air-to-refrigerant heat exchanger is used, and this is installed in the air passage between the air cooler 6 and the air heater 5.

The embodiment of FIG. 7 is similar to that of FIG.
The condenser 29p of No. 2 is used as an auxiliary heat source for air heating, and the brine produced by the refrigerator is switched to flow as a cold source to the air coolers 6a and 6b. 32 indicates a heat exchanger between this brine and the refrigerant. Also, 31
Reference characters a and 31b are switching valves for this brine, which are operated in accordance with the operation of the switching dampers 20a and 20b. FIG. 8 shows an example of a method for controlling the dew point temperature of air using this brine method. The amount of brine flowing into the air cooler 6 is adjusted by adjusting the opening of the control valve 34 so that the value of . According to this brine method, the dew point temperature can be controlled with higher accuracy.

In this way, by switching the air coolers 6a and 6b, the dew point temperature can be adjusted to between -10 and -20.
℃ dry air can be obtained without the problem of frost formation, and this dry air is heated to the working temperature by the air heater 5 and enters the HEPA filter 4, where it is purified and blown out into the working space 2. , a part or all of which circulates within the air circulation path 3, so that the inside of the work space 2 is always maintained in a clean and dry atmosphere.

As explained above, according to the present invention, air dehumidification processing that could not be achieved with conventional movable clean benches can be effectively achieved within this bench, and the dew point temperature can be maintained at 4°C or lower. Since it is possible to work in low-humidity air with a low dew point temperature, it is possible to further expand the work that has been done in the clean room, and its ease of use greatly contributes to improving work efficiency. I can do it.

[Brief explanation of drawings]

Fig. 1 is a front view showing an embodiment of the clean dry bench of the present invention, Fig. 2 is an equipment layout diagram showing the arrangement of equipment arranged inside the clean dry bench of Fig. 1 from the side, and Fig. 3 4 is an air processing system diagram showing another example of the air circulation system of the clean dry bench of the present invention; FIG. 5 is an air processing system diagram showing another example of the air circulation system of the clean dry bench of the present invention.
The figure is a system diagram showing a method of supplying a cold source to an air cooler, Figure 6 is a system diagram showing another example of a method of supplying a cold source to an air cooler, and Figure 7 is a system diagram showing a method of supplying a cold source to an air cooler. System diagram showing still another example of the source supply method, No. 8
This figure is an equipment layout diagram showing an example of the dew point temperature control method in the case of FIG. 7. 1...Casing body, 2...Work space, 3...
...Air circulation path, 4...HEPA filter, 5...
...Air heater, 6...Air cooler, 7...Casters, 8...Work table (punching board), 9...
...Work opening, 10... Shutter, 11... Blower, 13... Refrigerator, 14, 29... Condenser, 16... Air intake, 20... Switching damper, 22... Precooler, 28... Compression Machine, 30
...Expansion valve, 33...Dew point thermometer.

Claims (1)

[Claims] 1. A work space 2 and an air circulation path 3 are formed in a movable casing body 1, and the air circulation path 3 is
A HEPA filter 4 is installed in the HEPA filter 4, and this HEPA
In a clean bench that blows clean air from a filter 4 toward a work space 2, an air heater 5 is installed in the air circulation path 3 upstream of the HEPA filter 4, and an air heater 5 is installed in the air circulation path 3 upstream of the HEPA filter 4. The air circulation path 3 is branched into a plurality of air passages, an air cooler 6 is installed in each passage, and dry air with a dew point temperature of 4°C or less is produced by switching operation of the plurality of air coolers 6. A movable clean dry bench characterized by: