ISO 14644-1 Cleanroom Classifications

Cleanroom for Microelectronics Manufacturing

A question commonly asked is "What is a clean room?" Generally speaking a "clean room" is an enclosed room that has equipment which controls the amount of particulate matter in the air by using air pressure and filters. To meet requirements of a "clean room" as defined by Federal Standard 209E and newer ISO Standards, all clean rooms must not exceed a particulate count as specified in the air cleanliness class.

As of November 29th, 2001, the Federal Standard 209E has been replaced with ISO 14644-1. This method is simple; the number assigned to the class is the classification that the room must be designed to. In the Fed. Standard 209E, Class 1 was the cleanest. In the new ISO 14644-1 Standard, Class 3 is the cleanest. The difference? Generally speaking, the federal standards were measured in cubic feet and the ISO standards are measured in cubic meters.

What is measured in the air?: Class 3, 4, and 5 are based on the maximum number of 0.1 and 0.5 micron particles that are permitted in a cubic foot of air approaching any work operation within the room. Class 6, 7, and 8 are based on the number 0.5 micron particles.
What is a micron?: To give you an idea of what is being measured, one micron is one-hundredth the width of a human hair. The smallest particle seen with the naked eye is a 10 micron particle.
Where do these particles come from?: The clean room is under positive pressure, keeping out new particles from coming in. So where do they come from? We shed our outermost layer of skin every 24 hours, that is 1 billion flakes every 24 hours! One flake is about 35 microns.
What are the clean room classifications?: The ISO 14644-1 has changed these numbers to simple classes:

ISO 14644-1 Cleanroom Standards
Classification	Maximum Particles/m³						FED STD 209E Equivalent
Classification	≥0.1µm	≥0.2µm	≥0.3µm	≥0.5µm	≥1µm	≥5µm	FED STD 209E Equivalent
ISO 1	10	2.37	1.02	0.35	0.083	0.0029
ISO 2	100	23.7	10.2	3.5	0.83	0.029
ISO 3	1,000	237	102	35	8.3	0.029	Class 1
ISO 4	10,000	2,370	1,020	352	83	2.9	Class 10
ISO 5	100,000	23,700	10,200	3,520	832	29	Class 100
ISO 6	1.0 x 10⁶	237,000	102,000	35,200	8,320	293	Class 1,000
ISO 7	1.0 x 10⁷	2.37 x 10⁶	1,020,000	352,000	83,200	2,930	Class 10,000
ISO 8	1.0 x 10⁸	2.37 x 10⁷	1.02 x 10⁷	3,520,000	832,000	29,300	Class 100,000
ISO 9	1.0 x 10⁹	2.37 x 10⁸	1.02 x 10⁸	35,200,000	8,320,000	293,000	Room Air

The now defunct Federal Standard 209E classifications are as follows:

US FED Standard 209E Cleanroom Standards
Classification	Maximum Particles/ft³					ISO 14644-1 Equivalent
Classification	≥0.1µm	≥0.2µm	≥0.3µm	≥0.5µm	≥5µm	ISO 14644-1 Equivalent
1	35	7.5	3	1	0.007	ISO 3
10	350	75	30	10	0.07	ISO 4
100	3,500	750	300	100	0.7	ISO 5
1,000	35,000	7,500	3,000	1,000	7	ISO 6
10,000	350,000	75,000	30,000	10,000	70	ISO 7
100,000	3.5 x 10⁶	750,000	300,000	100,000	700	ISO 8
US Fed. Standard 209E was officially cancelled by the General Services Administration of the US Dept. of Commerce November 29, 2001, but is still widely used.

The British Standard BS5295 Classifications are:

BS 5295 Cleanroom Standards
Classification	≥0.5µm	≥1µm	≥5µm	≥10µm	≥25µm
Class 1	3,000		0	0	0
Class 2	300,000		2,000	30
Class 3		1,000,000	20,000	4,000	300
Class 4			200,000	40,000	4,000
BS 5295 Class 1 also requires that the greatest particle present in any sample does not exceed 5µm.

The GMP EU Classifications are:

GMP EU Classification
Classification	Maximum Particles/m³
	At Rest		In Operation
	0.5µm	5µm	0.5µm	5µm
Class A	3,520	20	3,500	20
Class B	3,520	29	352,000	2,900
Class C	352,000	2,900	3,520,000	29,000
Class D	3,520,000	29,000

Air Quality

A properly designed clean room must have a high rate of air changes to scrub the room of particulates. A Class 5 room can have an air change rate of 400 to 600 times per hour while a class 7 room can change at 50 to 60 changes per hour.

Testing and Certification

Once the room is completed, most specifications call for testing and certification. Some requirements state that the room should be tested annually also. Testing is usually conducted by an independent testing agency using the ISO Standards. It is also imperative for the owner to purchase a clean room monitor in order to determine the daily status of the room. This guide provides instructions on how to certify or test a cleanroom with a handheld particle monitor.

CleanPro® offers all types of cleanrooms, including mobile options along with monitoring, furniture and garments. Everything you need to start, maintain, or expand an existing cleanroom. Contact us anytime at sales@gotopac.com and let our clean room experts help you find what you need.

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