What does AMC pollution in the air mean?

AMC is the abbreviation of Airborne Molecular Contamination, which is usually called air molecular pollution in Chinese.

It refers to pollutants that exist in molecular form in the air. Unlike particles, these contaminants are at the molecular level, invisible to the naked eye and undetectable by conventional particle counters. They may come from outdoor air, process materials, equipment releases or cleaning agents, and their components include acid gases, alkaline gases, organic vapors, dopants, etc.

Just because the number of particles in the clean room is up to standard does not mean that the AMC is also up to standard. A HEPA or ULPA system can control particles very well, but has little ability to treat gaseous pollutants. If a process is sensitive to certain molecular contaminants, this will need to be individually assessed and controlled.

What are the common sources?

The sources of AMC are relatively complex and often not from a single channel.

outdoor air. Industrial emissions, traffic exhaust, and surrounding facilities may bring acid gases, organic matter, or other components. The location of the fresh air inlet and the surrounding environment directly affect the amount of fresh air introduced.

Craft materials. Cleaning agents, solvents, photoresists, adhesives, lubricants, etc. may evaporate during use. Different materials have different release components and amounts, which need to be analyzed in conjunction with specific processes.

Device release. Materials, seals, cables, and coatings inside equipment may release trace amounts of organic matter at operating temperatures. Such sources are easily overlooked, but can have an impact in precision processes.

personnel activities. Personnel's breath, sweat, cosmetics, and clothing fibers may bring in or produce certain gas components.

Cleaning and maintenance. The use of disinfectants, cleaners, and operations during maintenance may temporarily increase the concentration of certain gases.

When identifying sources, use a combination of material and air flow analysis, not just odors. Some AMC ingredients have no obvious odor but may still affect the process.

Why process goals are more important

The same gas has different effects on different products.

Photolithography-related processes may focus on alkaline components (such as ammonia), because alkaline substances may affect the exposure effect of the photoresist.

Electronic equipment protection may be concerned about corrosive gases, such as sulfur-containing compounds, chlorides, etc. These components may affect the reliability of metal lines and contacts.

Precision optics may be concerned about organic deposition, and certain volatiles may form a film on the lens surface.

Semiconductor manufacturing may concern dopants (such as boron and phosphorus compounds), and their presence in trace amounts may affect the electrical performance of the device.

Therefore, control projects should be built around actual sensitive objects rather than pursuing a general AMC indicator. Different process areas and different equipment may have completely different sensitivity to AMC and components of concern. For specific control plans, please refer to the chemical filter product range . Description of

How to connect detection and filtering

To control AMC, you need to first understand 'what to measure' and 'what to control'.

Identify the ingredients to be tested. Is it an acidic gas, an alkaline gas, an organic substance, or a specific dopant? Sampling methods, analytical instruments and detection limits vary for different components.

Determine the concentration range. Is it a normal environmental level, or does it need to be controlled at an extremely low concentration? The concentration range determines the choice of detection method and the design of the filtration scheme.

Select a sampling point. The fresh air inlet, return air, key workstations, and equipment interiors each reflect the pollution situation in different links. Paired sampling of inlets and outlets helps determine filtering effectiveness.

Then determine the filtering plan. According to the target composition, concentration, air volume and outlet requirements, select the corresponding chemical filter media and configuration method.

TVOC can observe the trend of some organic pollution, but it cannot represent acid gas, ammonia and all molecular pollution. If the project has requirements for specific ingredients, they need to be tested separately. involving MAU box-type chemical filters , the sampling points should cover the inlet and outlet. For fresh air treatment projects with

More than one means of control

Chemical filtration is an important means of AMC control, but it is not the only means.

Source control. Choosing low-release materials, improving processes, and strengthening local ventilation can reduce the generation of AMC from the source. This is often more economical than terminal processing.

Ventilation dilution. Increasing the fresh air volume or the number of air changes can reduce the concentration, but the energy consumption is high and may not be enough for certain low concentration requirements.

Chemical filtration. Select the appropriate media for the target gas and set up a filter section on the gas flow path. Suitable for handling low concentration, sustained release pollution.

Airflow organization optimization. Properly arrange air supply, return and exhaust paths to avoid accumulation of pollutants in sensitive areas.

In actual projects, these methods usually need to be used in combination. It is difficult to solve all AMC problems with one method alone. For specific configuration methods, please refer to FFU with chemical filter or An explanation of the difference between chemical filters and HEPA filters .

Project judgment example

A certain equipment area passed the particle test, but unknown contamination appeared on the surface of the product.

Preliminary inspection found no particle problem. Further testing revealed trace amounts of organic vapor in the air, originating from sealing materials and lubricants inside the equipment. These organic compounds are slowly released at operating temperatures and deposited on the product surface.

Treatment direction: First confirm the main pollution components, and then evaluate adding an appropriate chemical filter section to the equipment air supply path, or replacing low-release materials. The particle filtration system remains unchanged as it does not have the ability to handle this type of contamination.

This case shows that qualified particles do not mean that the air is fine. Processes that are sensitive to AMC require separate detection and control plans.

Key points for selection and acceptance inspection

About AMC control package of Aili Industrial

AMC control involves many links, from pollution identification and detection to filtration solutions, and it is necessary to match process requirements with system conditions.

Aili Industrial has independent manufacturing capabilities in filters, motors, fans, control systems and sheet metal processing, and can provide chemical filter product series and supporting air supply equipment. For projects that require AMC control, the target gas, concentration range, air volume and installation conditions can be combined to assist in checking the filter section configuration. When the filter is matched with FFU, MAU and other equipment, the resistance, interface and maintenance methods can be uniformly confirmed.

Related products:Chemical filter product series、MAU box chemical filter、FFU comes with chemical filter . Providing a list of target contaminants, testing requirements and system conditions during the inquiry will help confirm the appropriate configuration. The specific selection is subject to the technical documents and test results confirmed by the project.