Daily management of clean room

1. Personnel management

In various maintenance and management work, personnel management is the most important, because people are the main dust source of clean rooms. Foreign countries have very strict regulations on the management of clean room staff, and the following two points should be paid attention to:

1. Personnel who are not allowed to enter the clean room

① Those with sunburn, peeling, trauma, inflammation, and pruritus on the skin. (For personnel working in biosafety laboratories, when they have trauma, abrasions, skin lesions, and have just extracted teeth, they are not allowed to operate indoors with pathogens with a certain degree of danger)

② Those who have allergic reactions to chemical fibers and chemical solvents. (Can stimulate skin allergic reactions or spray)

③ Those with severe hand sweating. (The salt in sweat is a serious source of sodium ion pollution that seriously harms Semiconductor devices)

④ Those with a lot of nasal discharge.

⑤ Those who lose their scalp and hair too much.

⑥ Those with colds, coughs, and sneezes.

⑦ Those who have the habit of scratching their heads, picking their noses, touching their faces, and rubbing their skin. (Half of the dust particles found on semiconductor silicon wafers are in dandruff sludge)

⑧ Those who do not wash off cosmetics, nail polish and clean work clothes as required.

⑨ Those who sweat just after strenuous exercise.

⑩ Those who do not smoke or drink for more than 30 minutes. (Food residues in the mouth and smoke particles inhaled can be sprayed out again during talking and breathing)

(Figure 1: Clean room personnel management)

2. Matters to be noted in daily life

①. Try to take a shower every day, change clothes, wash your hair frequently, and keep your body clean. (Experiments and experience have proved that the skin becomes dry due to the shedding of the oil film on the skin surface after taking a shower, so the dandruff that falls off is no less than before taking a shower. Therefore, "taking a shower" here means that you only need to wash away the "floating dust")

② Men try to shave every day. (Because beards are easy to retain contaminated particles and microorganisms, workers in biological clean rooms, especially those who are engaged in airborne pathogens, should not grow beards. Even if you wear a gas mask, the presence of a beard is not good for flushing to play its function).

③ Wash your hands frequently, cut your nails, and apply moisturizer after washing your hands to prevent your skin from drying out.

④ Move gently in the clean room. Do not walk with your feet dragging, do not swing your arms, and do not make unnecessary movements or walks in the clean room. (Dust generated by movements is the main source of dust and should be controlled as much as possible)

⑤ Smoking and eating are not allowed in the clean room.

⑥ Wear gloves or finger cots as needed in the clean room, and do not expose your wrists. After wearing gloves, do not touch unclean things, including your body. (According to a survey, except for people sitting, 1/3 of the people in the clean room have their hands touching their faces at any time, and experience shows that even for people with delicate skin, a light touch of dark nylon gloves on the face will get a lot of dandruff) Gloves and finger cots should be changed frequently.

⑦ Do not unzip the clean clothes in the room. (Not only can the zipper itself generate dust, but the dust particles on the underwear are also scattered outside the body due to vibration)

⑧ All operations are carried out on the upstream side of the Clean air flow, and important operations should be carried out in the clean workbench to avoid cross contamination.

⑨Hand tools, utensils, notes, etc. should be put back into the covered box after use.

⑩The number of people entering the clean room should be kept to a minimum. The density of people in clean rooms of level 100 and higher should not exceed 0.1, and the density of people in clean rooms below level 100 should not exceed 0.25. The number of people and time entering the clean room in the morning and afternoon should be registered separately. The number and time of people other than formal staff entering the clean room should be registered (the purpose is to verify the dust source when there is a problem with product quality).

(Figure 2: No smoking)

2. Entry and exit system

1. Items not allowed to be brought into the clean room

① All items that have not been cleaned as required.

② Paper and pen. (Only plastic film paper and ballpoint pens can be used in the clean room, because the general paper and pen produce a lot of dust)

③ All personal items including keys, watches, handkerchiefs, notebooks, etc.

2. Personnel entry and exit system

① All personnel entering the clean area and clean room must follow the prescribed purification route and procedures and must not change. You must put on special slippers to enter the clean area, and you must put on special canvas slippers to enter the clean room, because ordinary slippers are easy to raise dust particles on the ground when walking.

② Outerwear and clean work clothes are stored separately in separate cabinets, and people entering the room must not enter the clean clothes changing room without taking off their outer clothes.

③ If there is an air shower at the entrance of the clean area, people entering must pass through the air shower, and after closing the door as required, raise their arms in the air shower and slowly turn their bodies 1-2 times for no less than 30 seconds.

④ Before entering the clean area, wipe the slippers on the shoe cleaner (mat) or on a wet mat. After entering the clean area, wash your hands at any time as needed, and then change your work clothes after washing your hands. Washed hands should be blown dry with a clean dryer, or wiped dry with a paper towel with less dust.

⑤ Wear clean clothes in a standing position, do not let the clean clothes touch the floor, workbench and other dusty things, and change into canvas shoes.

⑥ Wash your hands after changing into work clothes. Do not operate the purified elements, products and packaging materials with bare hands. You must wear clean gloves or finger cots to enter the clean room for operation.

⑦ When leaving the clean room, you do not need to pass through the air shower. After entering the locker room, change your shoes first, then take off your clean work clothes. If necessary, wash your hands according to the above matters before taking off your hat and changing clothes. When taking off your clothes, do not touch the ground or other places that may be dusty.

⑧ You cannot go to the toilet in clean work clothes (except for clean toilets). Going to the toilet should be handled according to the precautions for entering and leaving the clean room.

⑨ After the operation is completed, people working in biological clean rooms, especially biosafety laboratories, first take off their protective clothing and other laboratory-specific underwear (sterilized before taking them out of the clean room), then immediately wash their hands, shower, wash their faces, shave, brush their teeth, and finally do other things. Before washing your hands, you must not leave the laboratory or smoke, eat, or go to the toilet. Personal watches and other things must not be worn before washing your hands. Even if you use rubber gloves, you must wash your hands after the operation. Gloves may have small holes, cracks or scratches due to finger use which may leave a path for contamination.

(Figure 3: Air shower)

3. Selection and management of tools and equipment

The following are the key points to be noted

1. Sticky insoles must be replaced or regenerated regularly, or the thin layer of contaminated surface must be peeled off regularly, and wet mats must be cleaned every day.

2. The faucet of the hand-washing machine should be pedal-operated, not hand-twisted.

3. Special detergents, skin care products, hand dryers or paper towels with less dust should be prepared.

4. Workbenches and chairs should be made of materials with less dust, such as steel, aluminum, and good quality plastics with appropriate surface treatment. If possible, it is best to use stainless steel.

5. The structure of the clean workbench should be as simple as possible. Soft chairs with cushions are not allowed, and workbenches with drawers and side enclosures are not allowed.

6. The corners of the furniture should be rounded, and the legs and feet should be covered with rubber or plastic.

7. The height of the equipment cabinet should be convenient for wiping the top surface by hand, and the drawers should be pressed with small balls.

8. The transport truck should be made of stainless steel, hard plastic or steel and aluminum alloy with appropriate surface treatment. The load-bearing table should be made of special wear-resistant materials. The wheel bearings should be oil-free sealed bearings, and the wheels should be made of wear-resistant hard rubber.

9. Only plastic paper can be used for recording paper.

10. The note board cannot use ordinary blackboards and chalks. Only white boards, oil-based pens and special rags can be used, and they can only be placed in the preparation room.

(Figure 4: Clean room equipment)

11. The waste bin should be made of stainless steel, hard plastic or steel and aluminum alloy with appropriate surface treatment. It should be covered with a pedal-type cover. It is best to put a plastic bag for waste in the bin.

12. Check, replace and record the filters at all levels according to the specified content and cycle. The system primary filter should be cleaned once after a cumulative operation of 1 month. The medium-efficiency filter should be cleaned or replaced once after a cumulative operation of 2-4 months. The high-efficiency filter should be replaced when any of the following situations occur.

• When the air flow velocity is reduced to the minimum and the air flow velocity does not increase after replacing the pre-filter.

• When the resistance of the high-efficiency filter reaches twice the initial resistance and the resistance of all filters exceeds the fan capacity.

• When the high-efficiency filter has a leak that cannot be repaired.

• When replacing the high-efficiency filter, the plastic bag of the filter is only allowed to be unsealed on the spot during installation.

13. The air conditioner fan is the focus of the inspection. It mainly depends on whether the belt slips or falls off. You can press the belt between the driving wheel and the passive wheel by hand. The pressing weight should be 1.25-2.5cm. If the belt is too loose, the wind will drop; if it is too tight, it is easy to damage the bearing seat. In addition, the bearings should be refueled on time.

14. The air conditioner heat exchanger (cooler or heater) should focus on whether there is blockage between the plates. It should be cleared in time with high-pressure water when the blockage is not too serious. The cooler blades should also be regularly cleaned and sterilized with chemicals because bacteria are most likely to grow here.

15. Some metal impurities and scale accumulate in the water tray under the air conditioner humidifier. These dirt should be removed regularly to ensure the normal operation of the humidifier and avoid pollution.

The water baffle should be cleaned frequently, and the drainage point of condensed water should be checked and cleaned. These places are hotbeds for bacteria.

16. Insulation inspections should be performed regularly on motors used in air conditioners.

17. Equipment inspections of air conditioner fans, heat exchangers, humidifiers, motors, etc. should be conducted no less than twice a year.

18. When production is carried out in A Clean Room, the purification air conditioning system must not be stopped at will. If it needs to be stopped for some reason, the clean room staff must be notified first.

4. Hygiene and safety

The following are the key points to note

1. Cleaning of the clean room should be carried out after the process operation is completed before leaving get off work every day.

2. Cleaning should be carried out during the operation of the clean room purification air conditioning system, and regular inspections should be carried out according to different purification levels.

3. After the cleaning work is completed, the purification air conditioning system should continue to operate until the specified cleanliness level is restored, which is generally not shorter than the self-cleaning time of the clean room.

4. In order to prevent cross-contamination, clean rooms of different cleanliness levels have their own dedicated cleaning supplies, and the garbage swept together is put into plastic bags and taken out. The garbage swept out of the biosafety laboratory should be incinerated, and the used cleaning utensils should be immersed in medicine for disinfection.

5. Do not use fabric materials that are easy to lose fibers for cleaning mops and rags. Generally, silk, nylon, polyurethane sponges, etc. can be used.

6. For high-level clean room cleaning water, tap water should not be used, but filtered water should be used.

7. Clean room cleaning detergent can be prepared by adding 30 grams of neutral liquid detergent with low residue content per liter of water.

8. When large objects are moved into the clean room, they must be treated with a vacuum cleaner or wiping method first. During the shutdown of the clean room purification system, large objects are not allowed to be moved into the clean room.

(Figure 5: Clean room hygiene and safety)

9. Small objects that need to be brought into the clean room must be wiped clean first, and then enter the clean room through the transfer window.

10. The disinfectant used needs to be replaced regularly to prevent microorganisms from developing drug resistance.

11. When the purification air conditioning system is started, it is forbidden to turn on the return fan first. When the system is shut down, it is forbidden to stop the supply fan first, except for the single fan system. When the system is not running, the local exhaust system should not be turned on separately.

12. Positive pressure control devices should be checked regularly to avoid failure.

13. Firefighting equipment, safety doors, and safety passages in clean rooms should be marked with eye-catching signs, and staff should be familiar with their locations. Safety doors must be guaranteed to be open at any time, and no debris is allowed to be piled up in safety passages. Safety and fire protection facilities should be checked regularly.

14. When a fire occurs in a clean room, an alarm should be sounded immediately, the fan and all equipment in the clean room should be turned off, and the power supply and flammable gas passage should be cut off. (Systems equipped with fire dampers or fire switches will automatically turn off the fan when a fire alarm occurs, and they need to be manually reset afterwards.)

5. Clean clothes and their management

1. The fabrics of clean clothes should be selected from materials that do not generate static electricity or have been treated with anti-static agents, because the relative humidity in clean rooms is generally low, and some man-made fiber work clothes have extremely high electrical potentials, but after anti-static treatment, the electrical potential can be reduced by 80%, and the dust adhesion rate can be reduced by 90%.

2. It is better to separate the clothes and pants for clean clothes, but the top must be placed inside the pants. In addition, hats or shawls, canvas shoes, long shoe covers and gloves should also be equipped as needed.

3. When using a shawl hat in a high-level clean room, its hem should be placed inside the top. Hats are not allowed to be worn only on the back half of the head, and the hair on the upper part of the forehead and the ends of the hair must be completely covered.

4. For rubber gloves with talcum powder, the talcum powder must be removed before entering the clean room.

5. New clean clothes must be washed before use. If conditions permit, they can be washed with dust-free water or pure water, which is much better than washing with ordinary water.

6. Clean clothes should generally be washed once every 1-2 weeks, and washing, drying and packaging must be carried out in a clean environment to avoid re-attachment of dust particles.

(Figure 6: Cleanroom clean clothes)

6. Daily monitoring system

There should be a dedicated person responsible for the daily supervision and inspection of the main parameters of the clean room. Generally, the daily monitoring recommended items can be implemented according to the suggestions in the table below.

7. Handling of sudden pollution accidents

In addition to monitoring the clean room at ordinary times, sometimes we have to deal with sudden pollution accidents, mainly the sudden increase in indoor dust concentration and bacteria concentration. After the accident occurs, analyze and handle it calmly and carefully in the order of the table below. First, consider whether there is a sudden pollution source.

8. Establish records

The implementation of the above systems should be reflected in the handover, that is, a record system should be established.