The continuous technological advancement in production processes and strict quality and hygiene regulations have increased the need for cleanrooms or controlled-contamination environments. In this article, let’s find out more about cleanrooms and why indoor air quality for semiconductor companies is important.
What are Cleanrooms in Semiconductor Companies?
These are dedicated spaces or areas that have specific and strict air quality requirements.
Here, they control the contaminant presence to ensure optimal conditions of the processes
and the quality of the products.
Why is Air Quality for Semiconductors Important?
Contaminants basically refer to the airborne particles present in an environment such as dust, molds, gases, vapors, and other particulate matter. Semiconductor companies ensure to have quality indoor air in cleanrooms to prevent these particles to affect the overall quality of the product. A high level of contaminants in the processing area can expose the product to particles that can impact its freshness or its efficiency.
Cleanrooms commonly have filtration, distribution, recovery, and specific controls for handling air inside the room. They utilize air handling units (AHU) and devices to control the temperature and humidity conditions inside. Good control is vital in ensuring the system’s efficiency.
Photo Credit: R.P Fedder Industrial
How to Manage a Cleanroom Air Handling Unit
When managing a cleanroom air handling unit, control loops are important. Here are some examples of control loops that are useful in cleanroom AHU.
1. Fans
AHUs should basically control the fans to ensure a reasonable distribution flow rate, as determined by ISO 14644, along with the type of filter to acquire the necessary level of particulate separation. These days, inverter-controlled fans are utilized oftentimes to adjust speed and get the ideal flow rate. Flow control implies the air outlet speed from the outright filters can be changed; the last option is many times set in the false roof to make a laminar downwards flow, which prevents the development of the particles in an uncontrolled way.
A modulating fan is fundamental to keeping a consistent airflow rate, which in any case would diminish after some time because of the continuous accumulation of particles in the filters. To actually take care of this issue, it is important to change fan speed as indicated by the pressure difference read by a calibrated nozzle which, for radial fans, is frequently joined into the actual fan.
2. Pressure Gradients
Control of fan speed in light of differential pressure sensors is additionally helpful for keeping up with pressure gradients between neighboring rooms. To prevent infiltration of air from the outdoors with elevated degrees of air contaminants, the pressure inside the rooms should be higher than in neighboring, less controlled rooms.
On occasion, there are numerous levels with various classes, between which there should be a positive pressure gradient towards the less clean section; by and large, this is somewhere around 10-15 Pa or possibly 5 Pa between pre-sterile areas and the less controlled rooms.
For this situation, control includes keeping a differential pressure between two rooms by presenting more appropriately filtered outside air than the extracted air.
Pressure gradient control is likewise significant in certain frameworks in which contaminants, generally aeriform, like solvents or sanitizers, are produced during the process; for this situation, the air is taken in from the outdoors, treated, and afterward conveyed into the room. A different device then, at that point, separates the air from the room and releases it into the atmosphere. Once it is treated, the pressure gradient can be negative to keep toxins from getting away.
3. Temperature Control
Keeping up with the temperature-humidity conditions inside cleanrooms is significant for the processes. Moreover, a steady temperature is vital on the grounds that unexpected changes can make inclinations and produce convective movement, impacting the controlled laminar airflow and lifting dust from the surfaces.
Subsequently, controls are carried out in view of the supply air probe reading; the quantity of distribution cycles is with the end goal that in a brief time frame, the whole cleanroom arrives at a similar temperature as the supply air.
On the other hand, a more modern technique is to control the supply temperature utilizing a floating set point, as indicated by the temperature inside the room. Through this, airflow is steady and changes gradually if warm or cool air is expected to keep up with the ideal temperature in the cleanroom.
In Conclusion
The type of components and their proper positioning in an AHU or air handling unit as well as the right knowledge in managing its operation are vital in ensuring to meet the required specifications and the highest efficiency.
When building your own cleanrooms, it is important to find a reliable partner that can help you in managing the indoor air quality for semiconductor companies. Buoyant Industrial Systems offers quality products and services that can suit your specific requirements. We have significant experience in helping businesses build cleanrooms. Get in touch with us to find out more about how we can help you.
