Why do the particles attract

  1. Cleanroom glossary
  2. Particles

What's this?
Particles are the smallest, in solid or liquid aggregate state, air-borne suspended particles with defined physical properties. In cleanrooms, particles are a contamination and should be reduced to a non-critical level in most environments. Clean rooms are classified according to ISO or GMP based on the number and size of particles. Their size can vary by several µm.

This graphic compares the sizes of particles from our everyday environment. Fingerprint refers to the size of the particles left behind by a fingerprint. As a rule, only particles up to 5 µm are considered in clean room areas.

Table of Contents

  1. Application example
  2. use
  3. Individual evidence
  4. Selection of products on pure11

1. Application example

The deposition of the particles depends on the room maintenance, the number of staff in the room and the clothing concept. In order to keep the rooms as low as possible from particles and to ensure the protection of a product against negative impairment, several measures are essential:

With an emission of 1,000 particles that are ≥ 0.5 µm per person (without cleanroom clothing) and per second, humans represent the largest source of particles. After them, with decreasing influences on the particle content, come the processes, machines, operating resources and the air.
Particle-related rejects can have various causes and effects, depending on the product. These differ in the severity of their consequences, but they all entail high additional costs:

  • Insufficient sterility of injection solutions, implants or packaging for food
  • Functional defects such as leaky straight-way valves for gases and liquids, or incorrectly tripping circuit breakers
  • Failure / destruction of z. B. LED elements or short circuit in a semiconductor chip
  • Impairment of aesthetics: inclusions of particles in an LCD display or camera optics
  • Other defects such as B. acoustic impairments such as frictional noise from a PC fan or power steering

Particularly in the field of semiconductor technology, the particles (up to the order of magnitude in the nanoscale) are the focus of contamination problems.

2. Use

Particles in the clean room can be of different types. These include, for example, viruses, tobacco smoke, bacteria, hair, metal debris, or even sand. Depending on the type, a corresponding investigation or verification procedure is required.

The number of existing particles is determined using special particle counters. DIN EN ISO 14644-1 differentiates between the particle sizes 0.1 µm, 0.2 µm, 0.3 µm, 0.5 µm, 1 µm and 5 µm. GMP classes only consider particle sizes of 0.5 µm and 5 µm. The counting devices output the particle concentration of the individual particle sizes. The room can be classified according to the number of particles counted.

Appropriate cleaning and filtering are essential in order to ensure the protection of a product against negative impairment. Correct behavior on the part of staff is at least as important. Fast walking and rapid movements disrupt the directed flow and lead to a turbulence and horizontal spreading of the particles.

3. Individual evidence

  • Book: Reinraumtechnik, 4th edition

4. Selection of products on pure11

With the right cleanroom clothing, the amount of particles emitted by staff can be reduced to a minimum. Just contact us and we will be happy to advise you on the right clothing for your cleanroom.