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Cleanroom Design Checklist

There are seven critical items to get right when designing your new cleanroom. Be sure to get these right to make your new cleanroom a success.

#1: What class of cleanroom do you need? Most semiconductor cleanrooms are ISO-5/class 100.  Optics and laser cleanrooms are ISO-6/class 1000.  Printed circuit board cleanrooms are typically ISO-7 class 10k. Pharmaceutical cleanrooms are typically ISO-5 in critical filling areas and ISO-7 in other areas. Medical devices cleanrooms are commonly ISO-7/class 10k or ISO-8/class 100k. Cleanroom classifications define maximum particles allowed of each size and air changes per hour of HEPA filtered air.  

ISO 14644-1 Cleanroom Standards | Cleanroom Classifications
Class Maximum  Particles/m³ FED STD 209E equivalent
>0.1 um >0.2 um >0.3 um >0.5 um >1 um >5 um
ISO 1 10 2
ISO 2 100 24 10 4
ISO 3 1,000 237 102 35 8 Class 1
ISO 4 10,000 2,370 1,020 352 83 Class 10
ISO 5 100,000 23,700 10,200 3,520 832  29 Class 100
ISO 6 1,000,000 237,000 102,000 35,200 8,320 293 Class 1,000
ISO 7 352,000 83,200 2,930 Class 10,000
ISO 8 3,520,000 832,000 29,300 Class 100,000
Table 1. ISO Cleanroom Classifications
US FED STD 209E Cleanroom Standards | Cleanroom Classifications
Class Maximum  Particles/ft³ ISO equivalent
>0.1 um >0.2 um >0.3 um >0.5 um >5 um
 1 35 7 3 1 ISO3
 10 350 75 30 10 ISO4
100 100 ISO5
1000 1000 7 ISO6
10,000 10,000 70 ISO7
100,000 100,000 700 ISO8
Table 2. Fed Std 209E Cleanroom Classifications
Design Requirements for Cleanroom Classifications
Criteria Class 10 ISO4 Class 100 ISO5 Class 1000 ISO6 Class 100,000 ISO8
Air changes per HR/Min 500-600 / 8 to 10 300 to 480 / 5 to 8 180 / 3 60 /1 20 /0.33
Filter coverage % 90 – 100 60 – 70 20 – 30 7 – 15 4  – 5
CFM per square foot 85 – 90 36 – 65 18 – 32 9 – 16 4 – 8
Filter Efficiency 99.9997% ULPAs 99.997% HEPAs 99.997% HEPAs 99.997% HEPAs 99.97% HEPAs
Table 3. Air Changes per hour
Figure 1. Cleanroom gown room

#2: What size gown room? The gown room/airlock prevent the particles from entering the cleanroom when people enter and leave the cleanroom. It is also where workers put on their cleanroom garments so they don’t bring particulates into the cleanroom. The size of the gown room depends on how many people work in cleanroom as it is a bottleneck on entering and exiting the cleanroom.

Figure 2. Heat welded vinyl flooring and hands free cleanroom sink

#3: What kind of cleanroom flooring.? Bare concrete is very porous and will introduce too many particles into your cleanroom. A popular cleanroom flooring option is heat-welded vinyl to withstand strong cleaning agents for pharmaceutical and medical device cleanrooms. Epoxy or sealed concrete are popular options for industrial cleanrooms due to good durability and lower cost. Raised cleanroom flooring is used in class 100 semiconductor cleanrooms to allow air to flow directly from HEPA filters in ceiling into the floor for best laminar air flow.

Figure 3. Cleanroom air conditioner

 #4: What size cleanroom air conditioner? Cleanrooms are net heat generators and typically require a dedicated air conditioning system to maintain temperature.  The cleanroom design must take into account process heat load, exhaust cfm, # of personnel in cleanroom, heat from lighting, heat from HEPA filtration and temperature of warehouse when sizing the air conditioning.

Figure 4. Painted aluminum modular cleanroom walls
#5: What kind of cleanroom wall surface? The most important factor in selecting wall type is how you cleanroom your walls. Melamine/vinyl walls are fine for people using isopropyl alcohol or Simple Green. FRP is a popular chose for pharmaceutical cleanrooms due to its excellent chemical resistance. Static dissipative painted aluminum walls are common for electronics cleanroom where static electricity is a problem.
Figure 5. Dual Cleanroom Pass thru’s

#6: How will we move material in and out? Keeping the cleanroom clean while moving materials in and out of the cleanroom is very important. Options include pass thru’s for smaller items and material transfer rooms (cart pass thru’s) for larger items or pallets. Motorized roll up doors may be necessary for very large items.

Figure 6. Cleanroom with floor to ceiling windows

#7: How many windows do I need?  Cleanroom windows are a great way to give customers a tour of the cleanroom without having to get garbed up and enter the cleanroom. Windows also allow management to see what is going on in the cleanroom at any time. Finally, cleanroom windows allow works inside cleanroom to see outside of cleanroom which reduces claustrophobic effects of working in cleanroom.  Having enough cleanroom windows is important.

Property American Cleanroom Systems 2023

The author Anthony Chien has worked at American Cleanroom Systems for more than 10 years . He has more than 40 years of cleanroom experience. Anthony has a BS and MS in Electrical Engineering specializing in semiconductor manufacturing from the University of Illinois. American Cleanroom Systems is a design build modular cleanroom manufacturer based in Rancho Santa Margarita CA. It is expert in ISO-5 thru ISO-8 (class 100 to class 100k) modular cleanrooms for nutraceutical cleanrooms, pharmaceutical cleanrooms, medical device cleanrooms, and industrial cleanrooms.

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