CDA - Clean dry air for Semiconductor industry
Everything you need to know about CDA – clean dry air
What is CDA?
CDA stands for clean dry air, and it is a compressed air quality standard for the semiconductor industry. The air quality levels that are needed in this sector go way beyond those of most other applications. For good reason. There is hardly any other industry where contamination can have such devastating and expensive consequences.
In addition, while some applications require oil-free, dust-free or dry compressed air, in the semiconductor industry, it has to be all three. That is because any moisture, particulates/dust or oil in its cleanroom can ruin an entire batch of semiconductors and, more importantly, the stainless steel components of the machines producing them. This can cost millions of euros and dollars. Therefore, air quality is essential, and a reliable supply of clean dry air is crucial.
Clean dry air according to ISO 8573-1:2010
So how clean and dry does the air have to be?
It has to meet Class 0 of ISO 8573-1:2010, which is the international standard for air quality classes.
This standard defines how much of any of the three contaminant types the air may contain. The lower the class, the higher the quality of the air. Therefore, Class 0 means the least-contaminated air can be.
And to meet the requirements of a cleanroom in semiconductor production, the air should achieve Class 0 quality for moisture, oil, and for dust.
How to achieve Class 0 for moisture, oil and dust?
- It all starts with the right air compressor. An investment in an oil-free unit means that there is already one contaminant semiconductor producers no longer have to worry about.
- Next, special filters remove dust or other particles from the compressed air and keep them out of cleanrooms. You will need several of them to get to Class 0.
That takes care of the “clean,” but what about the “dry?” that will eliminate the risk of corrosion?”
- For that, you will need a high-performance dryer that can reach a pressure dew point (PDP) below -70°C. This kind of PDP can be achieved with a desiccant adsorption dryer. These desiccant dryers are the optimal choice for providing very dry air for critical applications.
Setting up a CDA compressed air system installation
But how does a typical CDA installation have to be set up to keep contaminants out of the cleanroom and achieve triple zero quality?
- First comes the oil-free compressor. Because the production of semiconductors requires a lot of energy, it makes sense to invest in an energy-efficient model. That can greatly lower operating costs.
- Next comes a pre-filter. Its job is to catch most of the particles in the compressed air. That way, the air that reaches the dryer is already much cleaner, which helps reduce its maintenance needs. While an adsorption dryer does a great job of drying the air, it may produce some desiccant dust. Therefore, the newly dried air is then routed through two after filters. They filter out the desiccant dust and further purify the air.
- At this stage, only the tiniest particles are left. Now, the air merely has to go through one more filter. Usually, this is a PTFE membrane filter that utilizes surface filtration technology to capture particles down to a size of 0.01 μm.
Following that final step, the clean dry air can now be used in a cleanroom environment without jeopardizing the semiconductor production.