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Cleanroom related concepts.
Cleanrooms, also known as cleanrooms, are often used as part of professional industrial production or scientific research, including the manufacture of pharmaceuticals, integrated circuits, CRT, LCD, OLED, and MicroLED displays. Cleanrooms are designed to keep extremely low levels of particulates such as dust, airborne organisms, or vaporized particulates. To be precise, a cleanroom has a controlled level of contamination that is defined by the number of particles per cubic meter at a specified particle size. A cleanroom may also refer to any given accommodating space in which the reduction of particulate pollution and the control of other environmental parameters such as temperature, humidity and pressure are set up.
Many industries use clean rooms, where small particles can adversely affect the production process. They vary in size and complexity and are widely used in industries such as semiconductor manufacturing, pharmaceutical, biotechnology, medical devices, and life sciences, as well as critical process manufacturing commonly found in aerospace, optical, military, and energy departments.
Detection metrics. 
Air volume or wind speed, indoor static pressure difference, air cleanliness level, number of air exchanges, indoor plankton and sedimentation bacteria, temperature and relative humidity, average speed, speed unevenness, noise, airflow pattern, self-cleaning time, pollution leakage, illuminance (lighting), formaldehyde, bacterial concentration.
1. Clean Operating Department of the Hospital:Wind speed, number of air exchanges, static pressure difference, cleanliness level, temperature and humidity, noise, illumination, bacterial concentration.
2. Clean workshop of pharmaceutical industry:Air cleanliness level, static pressure difference, wind speed or air volume, air flow pattern, temperature, relative humidity, illuminance, noise, self-cleaning time, leakage of installed filters, planktonic bacteria, sedimentation bacteria.
3. Clean workshop for electronics industryAir cleanliness level, static pressure difference, wind speed or air volume, air flow pattern, temperature, relative humidity, illumination, noise, self-cleaning time.
4. Clean room for food industry:Directional airflow, static pressure difference, cleanliness, air floating, air sedimentation bacteria, noise, illumination, temperature, relative humidity, self-cleaning time, formaldehyde, wind speed of the cross-section of the working area, wind speed of the developed cavity, fresh air volume.
Cleanroom airflow principle.
Cleanrooms control airborne particles by using the principle of laminar (unidirectional flow) or turbulent (turbulent, non-unidirectional) airflow through the use of HEPA or ULPA filters.
Laminar or unidirectional airflow systems direct filtered air in a constant downward or horizontal direction to a filter located on a wall near the cleanroom floor, or recirculated through a raised perforated floor panel. Laminar air flow systems are typically used on 80% of cleanroom ceilings to maintain constant air. Stainless steel or other non-shedding materials are used to construct laminar air flow filters and hoods to prevent excess particles from entering the air.
Turbulence, or non-unidirectional air flow, uses laminar flow air flow hoods and non-specific velocity filters to keep the air in the cleanroom in constant motion, although not all directions are the same. The coarse air tries to trap particles that may be present in the air and drives them to the floor, where they enter the filter and leave the cleanroom environment.
In some places, the vector clean room will also be added: the air supply in the upper corner of the side of the room is used to use a fan-shaped high-efficiency filter, or an ordinary high-efficiency filter can be used with a fan-shaped air supply outlet, and a return air outlet is set up in the lower part of the other side, and the height-to-length ratio of the room is generally 05 1 is advisable. This cleanroom can also achieve cleanliness class 5 (class 100).
Cleanroom Airflow Pattern Verification - Airflow Flow Pattern Detector].
4. The detection status of the clean room can be divided into three categories.
1) All pipelines in the clean room with complete empty facilities are connected and running, but there is no production equipment, materials and production personnel.
2) The production equipment is installed in the clean room with complete facilities and the remote transfer is tried according to the way agreed by the owner, but there are no production personnel in the field.
3) The dynamic facilities are in a state of operation in the prescribed manner, and the prescribed personnel are present to work in the prescribed manner.
Completion and acceptance of the clean room.
After the completion of the clean room and after it is put into production, it is necessary to carry out performance measurement and acceptance;In the event of a system overhaul or update, a comprehensive measurement is also carried out, and a comprehensive overview of the cleanroom must be carried out prior to the measurement.
The main contents include: the plan, section and system diagram of the purification air conditioning system and process layout, the requirements for air environmental conditions, cleanliness level, temperature, humidity, wind speed, etc., the air treatment plan, the return air, exhaust air volume and airflow, the organization of people and things, the purification plan, the use of clean room, the pollution situation in the factory area and its surroundings, etc.
(1) The visual inspection of the completion and acceptance of the clean room shall meet the following requirements
1. The installation of various pipelines, automatic fire extinguishing devices and purification air-conditioning equipment, air conditioners, fans, purification air-conditioning units, high-efficiency air filters and air blowing chambers should be correct, firm and strict, and their deviations should comply with relevant regulations.
2. The connection between the high and medium efficiency air filter and the support frame and the connection between the air duct and the equipment should be reliably sealed.
3. All kinds of adjustment devices should be tight, flexible and easy to operate.
4. There is no dust in the purification of the air conditioning box, static pressure box, air duct system and air supply and return air outlets.
5. The inner wall, ceiling surface and ground of the clean room should be smooth, flat, uniform in color and luster, no dust, and no static electricity on the floor.
6. The sealing treatment of the crossing place when the return air outlet and various terminal devices, various pipelines, lighting and power line piping and process equipment pass through the clean room should be tight and reliable.
7. All kinds of switchboards, cabinets and electrical pipelines and nozzles entering the clean room in the clean room should be sealed reliably. 8. All kinds of brushing and insulation work should comply with relevant regulations.
Cleanroom environmental control.
There are eight main items of environmental control in a clean room, which are arranged as follows according to the order in which they are achieved:
Among them, illumination and noise will affect the comfort of staff;Cleanliness, positive pressure, static air resistance, and FFU leakage will affect the semiconductor manufacturing processTemperature and humidity affect both the comfort of personnel and the manufacturing process. Specific production processes have high requirements for temperature and humidity, and cleanliness will affect process yield. Therefore, in daily operation, IPQC will control cleanliness, temperature and humidity.
Generally speaking, a high concentration of dust particles in the air is low for air cleanliness, and a low concentration of dust particles is high for cleanliness. The level of cleanliness can be distinguished by the cleanliness level. The cleanliness level is determined by the number of allowable particulates per cubic metre of air. ISO-14644 is an international standard, which is now adopted in the United States, Europe, Japan, Russia and China. The United States originally used the American Federal Standards 209a, b, c, d, and e, but now the United States does not use them. It turns out that the 100, 1000, 10000 and 100000 classes we are familiar with are all derived from the US federal standard FS 209B. According to the ISO 14644 series of international standards, cleanrooms can be divided into nine levels, from Class 1 to Class 9, with Class 1 having the highest cleanliness and Class 9 being the lowest.
The cleanliness level standards of ISO-14644 are as follows:
Among them, Class 1 and Class 2 cleanrooms are commonly used to manufacture high-precision products such as hard disk drives and electronic devices. These cleanrooms are very demanding and require strict control of the concentration and temperature of suspended particles in the air. Class 3 to 8 cleanrooms are suitable for manufacturing processes in different industries, such as semiconductor manufacturing, pharmaceutical, and medical device manufacturing. These cleanrooms have different control requirements, but all need to keep the concentration and temperature of suspended particles in the air within the specified ranges. Class 9 cleanrooms are the least stringent grade and are typically used in situations where a highly controlled environment is not required, such as warehouses and offices.
Basis for clean room environmental testing.
Including specifications, drawings, design documents and technical data of equipment, etc., it is divided into the following two categories.
1. Design documents, supporting documents for design changes, relevant agreements, and as-built drawings.
2. Technical data of the equipment.
3. "Code for Design of Clean Workshop" GB50073-20012, Construction and Installation "Code for Construction Quality Acceptance of Ventilation and Air Conditioning Engineering" GB50243-2002
Detection method and result judgment.
(1) Test of air volume or wind speed
Air volume hood
1. Sampling to detect the area with design requirements.
2. The air volume and wind speed must first test the effects of the purification air conditioner, and it must be obtained under the designed air volume and wind speed conditions.
1) The measured air volume value of the turbulent clean room system should be greater than the respective design air volume value, but should not exceed 20%;The difference between the measured fresh air volume and the designed fresh air volume should not exceed 10% of the designed fresh air volumeThe difference between the air volume of each air outlet in the room and the respective design air volume should not exceed 15% of the design air volume.
2) The measured average indoor wind speed in the unidirectional flow laminar flow clean room should be greater than the design wind speed but should not exceed 20%;The difference between the total measured fresh air volume and the designed fresh air volume should not exceed 10% of the designed fresh air volume.
(2) Indoor static pressure difference test
1. Instruments and equipment and environmental measuring instruments, tilt micromanometer, digital micromanometer, etc. Ambient temperature: at room temperature or design temperature.
2. Sampling and testing of each adjacent area with design requirements.
3. The static pressure difference test result shall comply with the following provisions.
1) The static pressure difference between adjacent clean rooms of different levels and between clean rooms and non-clean rooms should not be less than 5Pa.
2) The static pressure difference between the clean room and the outdoor should be greater than 10pa.
3) The unidirectional flow laminar flow clean room with a cleanliness degree higher than 100 is 0Concentrations above the upper limit of the indoor level should not be measured at 6m.
(3) Leakage of air filters
Aerosol photometer 3990
Aerosol photometer 3991
Cold Hair Aerosol Generator 01
Hot Aerosol Generator 02
Cold Hair Aerosol Generator 03
Pao oil. High-efficiency filter leak detection system].
1. Instruments and equipment and environmental measuring instruments, aerosol photometers, aerosol generators. Ambient temperature: at room temperature or design temperature.
2. Before the sampling high-efficiency filter body enters the site, the manufacturer shall conduct a performance test according to the regulations and provide a certificate. Leak detection should be carried out on a one-way flow clean room for the installation of high-efficiency air filters on a one-way flow basis, and for a class 7 or lower cleanroom in a turbulent flow clean room, leak detection can be omitted as long as the clean room meets the required air cleanliness level.
3. The results of leak detection of technical requirements should meet the conditions: the leakage concentration measured by the downwind side of the tested filter is converted into a transmittance rate, which should not be greater than 2 times of the factory pass rate of the filter for high-efficiency filters, and should not be greater than 3 times of the factory pass rate for ultra-high efficiency filters.
4. The leak detection of the operation process and judgment filter refers to the leak detection of the installed air filter, which is suitable for empty or static clean rooms.
(4) Air cleanliness level
Handheld particle counter.
Portable particle counter.
Benchtop particle counter.
*Particle sensor 5104
* Particle sensor R5
A full range of particle counters.
Dust particle counters of all kinds].
1. Instruments and equipment and environmental measuring instruments dust particle counters. Ambient temperature: The temperature and relative humidity of the cleanroom area should be adapted to its production and process requirements.
2. The location and number of sampling points
a.Minimum sample size for each cleanliness determination;
b.The minimum number of sampling times for each clean area is 3 times, and when there is only one sampling point in the clean area, at least 3 samples will be taken at that point
d.For environments where an expected air cleanliness level of 4 or cleaner is expected, the sequential sampling method specified in Annex F of ISO14644-1 can be used for large sampling volumes.
3. Technical requirements
The average particle concentration CI at each sampling point should be less than or equal to the limit specified in the cleanliness class;
The 95% confidence upper limit of the average particle concentration n for all sampling points should be less than or equal to the limit specified by the cleanliness level.
4. There are many kinds of indoor plankton and sedimentation bacteria in the determination of suspended microorganisms in the air, but the basic process of their determination is through the process of trapping, cultivation and counting, and the test methods of plankton and sedimentation bacteria are currently adopted.
Planktonic microbial sampler].
1) Before the test of petri dishes, microbial samplers, constant temperature incubators, planktonic bacteria and sedimentation bacteria, the temperature and humidity of the tested clean room area must meet the specified requirements, the static pressure difference must be controlled within the specified value, and the tested clean room area has been disinfected.
The preparation of the sampling device before sampling and the treatment after sampling should be operated in the negative pressure laboratory of the exhaust air of the high-efficiency filter, and the test status is static and dynamic, and the test status is indicated in the report.
Testers: Testers must wear uniforms that meet the cleanliness level of the environment. During static testing, no more than 2 indoor testers are allowed.
2. The location and number of sampling points
The indoor plankton measurement point and the cleanliness measurement point can be the same, and the sampling must be carried out according to the steps described in the instructions of the instrument used, and special attention should be paid to the disinfection and sterilization of the instrument before testing. For the determination of sedimentation bacteria, the petri dishes should be arranged in a representative location and a place with minimal airflow disturbance.
3) Technical requirements: indoor plankton and sedimentation bacteria should meet the design requirements.
4) Operation process and judgment.
Tests for planktonic bacteria
a.First of all, the surface of the test instrument and petri dish should be strictly disinfected, and when the sampler enters the test room, it should be sterilized with the disinfectant in the disinfection room. Samplers used in Class 5 clean rooms should always be placed in clean rooms.
b.Samplers should wear clean clothes and disinfect their hands.
c.Start the vacuum pump to pump air so that the residual disinfectant in the instrument evaporates for no less than 5min, and adjust the speed of the flow turntable. Turn off the vacuum pump, put in the Petri dish, and adjust the sampler after the lid is closed.
d.After setting the sampling port at the sampling point, turn on the sampler, vacuum pump, rotate the timer, and select the sampling time according to the sampling amount. After all the sampling is completed, the petri dish is inverted in a 30-35 constant temperature incubator for no less than 48 hours.
e.Count directly with the naked eye, then check with a 5-10x magnification glass for omissions, and if there are two or more colonies overlapping on the plate, still count with two or more colonies.
Testing of sedimentation bacteria.
For one-way flow, such as 5-level purification room and laminar flow workbench test, it should be started after the normal operation of the purification air conditioning system for no less than 10 minutes;For non-unidirectional flow such as grade 7 and grade 8 or above, the clean room test should start at least 30 minutes after the normal operation of the purification air conditioning system.
a.Sampling method: Place the prepared Petri dish at a predetermined sampling point, and open the lid of the Petri dish to expose the surface of the medium 0After 5 hours, the Petri dish is covered and inverted.
b.After all the samples were completed, the Petri dish was incubated inverted in a constant temperature incubator. At 30-35 the incubation time is not less than 48 h. Each batch of medium should have a control test to check whether the culture itself is contaminated, and 3 petri dishes can be selected for each batch for control culture.
c.Colony counting is done directly with the naked eye, and then checked for omissions with a 5-10x magnifying glass. If there are 2 or more colonies overlapping on the Petri dish, 2 or more colonies can still be counted when they can be distinguished.
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