How to confirm the installation direction of high-efficiency filters in semiconductor equipment?

Reverse installation is not very common on FFUs on factory ceilings - the air outlet faces downwards and the direction is basically fixed. But inside semiconductor devices, the situation is not so intuitive.

The equipment cover has openings, pipes, and mechanical moving parts. You can't tell where the air comes in and where it comes out just by looking at the appearance. The EFU of some equipment is installed on the side wall, some is installed on the top, and some have corners for the air inlet and outlet. If the installation direction is wrong, the problem may not be visible in a short time, but the wind speed distribution, filter element stress and sealing state will deviate from the design state.

Start with the fan and follow the airflow

The most reliable way to confirm the direction is to walk along the airflow path instead of just looking at the arrow on the filter element.

The starting point is the blower. Locate the fan position of the EFU or equipment air supply unit and confirm its air outlet direction. Then follow the air duct and diversion structure downwards to see which structural parts the airflow passes through, where it turns, and where it finally enters the sensitive area.

There may be diffusers, flow nets, and air duct elbows in the middle. These structures will affect the direction of the airflow. The internal air path of some equipment is not straight, and the air outlet of the fan and the air inlet surface of the filter element are turned at an angle. At this time, it is easy to make a wrong judgment just by looking at the arrow of the filter element.

Marking this path on the equipment drawing and comparing it with the actual assembly position is more reliable than inferring from experience.

You should look at the logo on the filter element, but you can’t rely on it alone.

The outer frame of regular products will be marked with an airflow direction arrow. This logo is the design direction, not the installation direction.

What's the meaning? The arrow points to the direction of the designed air flow through the filter element, but after it is installed in the device, whether the actual air flow direction is correct depends on the air path design of the device. If the internal air path of the equipment is different from the drawing, or if the fan direction or air duct connection changes, the direction of the arrow may not be correct.

There is another situation: the protective net or sealing surface design of some products is symmetrical and can be installed front and back, but only one direction is correct. If this type of product is not clearly labeled, or if the label is obscured by packaging, it is easy to install it incorrectly on site.

Sealing surfaces and protective structures will give clues

In addition to the arrows, the structure of the filter element itself can also provide a basis for judgment.

The sealing gasket or liquid tank is usually located on the air inlet side or the air outlet side, depending on the box design. The positions of the pressing surface, protective net, and diversion structure all correspond to the design direction. Comparing these features with the box structure can cross-verify whether the direction is correct.

If after the filter element is installed, the pressing piece cannot press the sealing surface, or the position of the sealing gasket and the contact surface on the box do not meet, there is most likely a problem with the direction. This kind of assembly anomaly is more direct than looking at arrows.

For the EFU involved in liquid tank sealing, the mating direction of the blade edge and the tank body must also be confirmed during assembly. For specific verification methods, please refer to the relevant interface instructions.

How to verify after installation

Whether the direction is correct or not ultimately depends on operational verification.

After assembly is completed, measure the wind speed and distribution in the target area at the actual working gear. If the direction is correct, the wind speed should fall within the design range and be relatively evenly distributed. If the wind speed on a certain side is obviously low or there are local abnormalities, the direction problem should be included in the investigation.

Perform installation leak detection according to project requirements, focusing on the interface between the filter element and the box. Reverse installation may cause the stress state of the sealing surface to change, and the location of the leakage point may be different from that during normal assembly.

There are often multiple fans and air supply outlets inside the equipment. When verifying, confirm them one by one and do not assume that they are in the same direction. If changes are made during the equipment debugging stage, such as replacing the fan or adjusting the air duct, the direction must be rechecked.

Keep an assembly record

After the equipment is delivered or maintained, record the filter number, installation direction, compression method and operating gear of each location, and attach photos.

When the filter element needs to be replaced after the equipment has been running for a period of time, this record can directly tell the maintenance personnel how it was originally installed. The maintenance window for semiconductor equipment is usually tight, and it takes a lot of time to turn over drawings and re-judge the direction on site.

If the equipment has multiple machines of the same model, it is recommended to unify the assembly direction and recording format to facilitate maintenance personnel to rotate operations between different machines.

About Aili Industrial’s equipment support

Ai Li industrial The EFU equipment-side fan filter unit supports ultra-thin structure and small size customization, and can be matched with HEPA/ULPA air filters are used inside semiconductor equipment. Since the fan, air duct, box and filter are designed in the same manufacturing system, the air flow direction, sealing surface position and assembly structure can be uniformly confirmed before leaving the factory.

For equipment-side projects, it is recommended to provide the internal structure diagram of the equipment, the position of the fan, the target area and the available installation space, so as to facilitate the determination of the installation direction and interface matching method of the air supply unit. involving For FFU fan filter units or other end-type systems, it is also recommended to confirm the interfaces at the equipment end and factory end separately to avoid mixing. Specific performance is subject to product technical data and project acceptance results.