What cleaning scenarios are ULPA filters mainly used for?

Where is ULPA used? If you only look at the industry name, it is easy to answer this question incorrectly.

It's not 'all semiconductors use ULPA', nor is it 'pharmaceuticals must be super efficient'. Where ULPA is used depends on how strict the particle control requirements are at that location and what the verification method is. In the same factory, some areas use ULPA, some use HEPA, and some locations don't even need high-efficiency filtration. This is not because the configuration is not uniform, but because it is allocated on demand.

The whole room plan and the partial plan are two ideas

The application scenarios of ULPA can be roughly divided into two categories.

Whole room solution : The entire clean room or large area uses ULPA as the terminal filtration. This type of solution involves a series of system design issues such as filter coverage, return and return air organization, and the impact of personnel activities. When selecting, you should not just look at the room grade name, but also consider whether the air flow is uniform, whether there are any dead corners, and whether the return air path is reasonable.

Local solution : ULPA is only used inside key workstations or equipment, and the surrounding areas are treated by other levels of filters or systems. The focus of this type of solution is to define the scope of protection—which area must meet the standards, where the boundaries are, and whether equipment movement will destroy airflow coverage. Device-side applications such as The EFU equipment-side fan filter unit falls into this category, and the filter element must be considered together with the equipment structure.

The two types of solutions cannot apply the same set of selection logic. Whole-room solutions focus more on system balance, while local solutions focus more on interfaces and structural constraints.

Dust production inside the equipment is an unavoidable problem

The inside of semiconductor equipment and precision manufacturing equipment is often not 'clean'.

Particles may be generated due to robot movement, transmission mechanism friction, cable wear, and maintenance operations. If these particles are generated near sensitive areas, local concentrations may be affected even if the incoming air itself is qualified.

ULPA air supply can cooperate with the air flow organization to take away these particles, but it cannot replace pollution source control . If the dust generation point is just above the wafer, improving the filtration level or increasing the air volume will have limited effect. In actual projects, it is often more effective to first locate the location of dust generation and adjust the direction of air flow than to replace it with a higher-grade filter element. involving When the FFU fan filter unit is used together, the air supply direction of the unit and the internal structure of the equipment also need to be considered.

Some locations are not suitable for direct use of ULPA

ULPA is not a universal solution, and there are a few locations where you need to be particularly cautious.

Situations with high dust and obvious oil mist. This type of airflow contains a large number of particles or viscous substances. Directly entering the ULPA will quickly block the filter material, cause the resistance to rise quickly, and require frequent replacement. In this position, the pretreatment plan needs to be evaluated first to digest most of the load in the front stage so that the terminal ULPA can work normally.

Occasions with obvious gaseous pollution. ULPA deals with particles. Odors, solvent volatiles, and acidic gases require chemical filtration or other treatment methods. When configuring the chemical filtration section, attention should be paid to the order and resistance superposition with the particle filtration section.

Process exhaust and safety equipment. This type of system has specialized functions and certification requirements, and the configuration ideas for clean air supply cannot be simply applied. Whether and how it can be used at a certain location depends on the specifications and risk assessment adopted by the project.

Project judgment example

In the same factory building, the control objectives of the wafer handling station and personnel passage are completely different.

There are mechanical movements and product exposure near the handling station, and the requirements for particle control are high, so they may be the key protection targets of ULPA. The main control of the personnel passage is the overall environmental cleanliness. HEPA combined with a reasonable number of air changes is usually enough. If the same configuration is used for two positions, either the workstation protection is insufficient or the channel is overcommitted.

The correct approach is to list the control targets in each area separately and then map them to the filtering plan. involving For HEPA/ULPA air filter products of different grades, the testing requirements and verification methods should also be clearly stated in the project documents.

Selection and Acceptance Checklist

About Aili Industrial’s application packages

The application scenarios of ULPA are relatively scattered. Some are whole-room systems, and some are local air supply at the equipment end. The interface conditions and structural constraints are very different.

Aili Industrial's manufacturing system covers filters, motors, fans, control systems, sheet metal and complete machine assembly, and can provide products of different structures. ULPA ultra-high efficiency filter and supporting air supply equipment. For device-side projects, filters can be used with the EFU equipment-side fan filter unit ; for clean room projects, it can be Check the installation space, air volume and control method together with The FFU fan filter unit is matched to confirm the terminal configuration.

When enquiring, provide protection objects, area boundaries, target air volume and upstream pollution conditions, which will help determine which location is suitable for ULPA and what structure to adopt. The specific configuration is subject to the technical documents and acceptance conditions confirmed by the project.