Cleanroom classification is often one of the most confusing parts of designing and building a cleanroom. However, it’s also one of the most essential parts, so it’s important that you understand all the relevant information.  If you’re installing a cleanroom for the first time, you probably understand that every type of cleanroom requires a different classification, but you’re bound to have a number of other questions — and that’s okay! We’re here to help. Below, we’ll provide answers to some of the most common cleanroom classification questions we receive.

1. What are cleanroom classifications?

Cleanroom classifications regulate a cleanroom’s degree of cleanliness. They’re defined by the allowed amount of contamination, by particle count and size, as well as the air change rates necessary to maintain that.  There are a variety of classification types that regulate cleanroom cleanliness, but the main system was developed by the International Standards Organization (ISO). ISO classifications apply to all cleanroom industries and applications, and range from Class 1 (most clean) to Class 9 (least clean, regular room air). 

2. What cleanroom classification do I need?

It depends on your industry and application. The requirements will vary depending on the size of particles that need to be filtered, the sources of contamination present, and the recommended air change rates. If your industry is regulated by the government, you can check applicable regulations to see what cleanroom classification is required. If you work in a sector that isn’t regulated by the government and that doesn’t have an industry default, you’ll need to determine the appropriate classification for yourself, based on your application’s needs.  Below, we’ll explore recommended cleanroom classifications for a few popular industries. For a full list of industries and their cleanrooms classifications, visit our cleanroom industries page. 

What cleanroom classification is best for aerospace applications?

Aerospace applications require control over mechanical, thermal, chemical, and electrical properties within the cleanroom. In most cases, their cleanrooms need to meet at least a Class 7 ISO classification. However, in highly sensitive applications like spacecraft hardware, fine electronic, and optical device development, a more stringent classification is necessary.

What cleanroom classification is best for manufacturing applications?

There are various types of manufacturing processes, all with different needs in terms of humidity, contamination, pressure, and temperature control. However, most manufacturing cleanrooms tend to be required to meet ISO Classes 7 or 8. 

What cleanroom classification is best for medical applications? 

There are a few sub-categories that fall under the broad category of medical cleanrooms, including medical research, medical device, and pharmaceutical cleanrooms. All of these cleanrooms have some of the most stringent classifications in order to protect the safety of operators and consumers. 

• Medical research: ISO Class 5-7
• Medical device: ISO Class 5-8
• Pharmaceutical: ISO Class 5

What cleanroom classification is best for semiconductor applications?

Contamination is a large source of production issues and product failures in semiconductors and microelectronics, so it’s critical that the cleanrooms they’re manufactured and packaged in are filtered appropriately. In most cases, semiconductor cleanrooms will hold ISO Class 4-6 requirements. 

3. How often should I test my cleanroom to see if it’s meeting classification requirements?

ISO requires that air pressure difference and airflow be tested every 12 months for all classifications. For ISO Classes 6-9, particle tests must also be performed every 12 months, but for ISO Classes 1-5, those particle tests must be performed every six months.  The following tests are recommended for all ISO Classes, every 24 months:

• Installed filter leakage
• Containment filter leakage
• Recovery
• Airflow visualization

4. How often do I need to have my cleanroom inspected?

That depends on your cleanroom classification. The more stringent the classification, the more regular the inspections. Inspections may coincide with compliance testing, so they could occur every 6-12 months, depending on your specific requirements. 

5. How does cleanroom classification affect my budget?

In general, the more stringent your cleanroom classification, the greater the cost. Strict classifications require more air, energy, advanced technology, and equipment, so their prices reflect that. For a more detailed breakdown of the costs, you can check out our blog, “How Does Cleanroom Classification Affect Your Cleanroom Budget?”

6. Can I redesign my cleanroom to fit a different classification?

Yes. Every facility’s needs change over time. A cleanroom from Angstrom Technology can change right along with them. All of our cleanrooms are “backward compatible,” meaning their size can expand or decrease and their fan filter units can be added or removed to keep up with any changes in cleanroom classification requirements.  Have any questions about your cleanroom classification and how to reach it? Contact the experts at Angstrom Technology! We’re happy to walk through your specific requirements and help design and build the best cleanroom for your facility and application.

To ensure the highest levels of quality, safety, and repeatability in semiconductor chips and the devices they’re installed in, semiconductor manufacturers must carry out processes in a controlled cleanroom environment. But while the right cleanroom can achieve this control and minimize risks, there are still a number of potential threats to be mindful of. 

Let’s take a look at some potential threats to semiconductor cleanrooms in the manufacturing process, as well as how to design a cleanroom that defends against them all. 

Why Do I Need a Semiconductor Cleanroom?

Semiconductors are highly sensitive materials, vulnerable to even the tiniest speck of dust or the slightest increase in temperature. Therefore, any task that involves the production, manipulation, installation, or packaging of semiconductors must be done carefully in a cleanroom. The value of cleanrooms for semiconductor applications is indisputable. 

If not handled properly in a controlled environment, semiconductors and the devices they’re installed in can easily face product failure — which can lead to disastrous consequences depending on the type of product in question.

4 Biggest Threats to Safe Semiconductor Manufacturing

Particulate matter, static electricity, humidity, and outgassing. Although they may seem relatively low-risk when encountered in day-to-day life, these environmental conditions can pose significant threats to semiconductor manufacturing. These threats can go on to harm workplace productivity, disrupt the quality of end products, and endanger the safety of workers and consumers alike. 

Here’s some more guidance on the damage these factors can cause, as well as how to prevent it. 

1. Particulate Matter in the Semiconductor Cleanroom

Just like with any other cleanroom, particulate matter poses an incredible risk to semiconductor applications. This can include airborne particles like dust, viruses, and bacteria — but one of the most common threats here is human contamination. It’s also one of the most difficult to control.

Things like shedding skin cells, breaking fingernails, and coughing can all disrupt the semiconductor manufacturing process. Cleanroom operator gowns, gloves, and other PPE work to protect semiconductor processes from the human element, but they also protect workers from dangers in the cleanroom setting (in accordance with ANSI and OSHA requirements). 

How to Control Particulate Matter in Your Semiconductor Cleanroom

There are a few main ways to lessen the risk of cleanroom operator contamination: proper gowning (PPE) and air shower walkthroughs. In addition to that, your cleanroom should be equipped with powerful HEPA filters to continuously filter any dangerous particles out of the cleanroom environment.  

2. Static in the Semiconductor Cleanroom

Electro-static discharge (ESD), even at a microscopic level, is another leading cause of defects in silicon wafers and semiconductors. Static corrupts materials by drawing and adhering fine airborne particles to the products’ surface, ultimately resulting in product rejection or failure. 

Static can also pose a threat to semiconductor cleanroom operator safety. When static charges are allowed to build up, they can release suddenly in an uncontrolled manner and harm workers, either through electric shock or involuntary movement. 

How to Control Static in Your Semiconductor Cleanroom

Preventing static from harming your semiconductor cleanroom and manufacturing process starts with intentional cleanroom design and material choices. The most important thing to understand is that conductive materials are often more effective than insulative materials in sensitive applications like this one. Conductive materials allow electrons to flow quickly away from areas where they could build up, directing them safely to the ground. 

3. Humidity in the Semiconductor Cleanroom

Many products that are manufactured and tested in semiconductor cleanrooms are sensitive to moisture, so control of relative humidity (RH) is crucial. Most semiconductor cleanrooms must maintain RH at 35-65%, in addition to temperatures at 70°F or lower. 

Fluctuating humidity and temperature levels — even within that range — can present many threats to both productivity and product quality. From inconsistent bake-out times to evaporation of solvents to surface swelling and corrosion, any inconsistency in production control can have a negative impact. 

How to Control Humidity in Your Semiconductor Cleanroom

To control and maintain relative humidity, semiconductor cleanrooms require powerful HVAC systems to treat air before it’s filtered and released into the space. These HVAC systems are often independently dedicated to the cleanroom (rather than being integrated with the larger facility’s system) to allow for total control and boosted power. 

4. Outgassing in the Semiconductor Cleanroom

Outgassing is the release of gas that was previously trapped or stored within a solid material. It’s a common concern with electronic equipment and high-frequency circuit boards — the exact products that semiconductors help function. 

All the machines within a semiconductor cleanroom can experience outgassing, and the gas released can harm the manufacturing environment and process.

How to Control Outgassing in Your Semiconductor Cleanroom

There’s not a proven way to fully avoid outgassing. Instead, you can only do your best to prevent and control it from reaching harmful levels. A powerful cleanroom HVAC and filtration system can help to circulate and filter the air regularly so that any contaminated air is quickly taken care of and replaced with cleaner air. 

Another suggestion is to ensure your cleanroom equipment is properly taken care of. Well-maintained equipment often results in less outgassing. 

Basic Semiconductor Cleanroom Design Considerations

Semiconductor manufacturing is highly sensitive and requires that all cleanroom systems work together to comply with strict cleanliness standards. Most semiconductor cleanrooms fall within ISO Class 4-6 requirements, which means they have some of the most stringent particle count requirements of any other industry. 

As factors like human contamination, static, humidity, and outgassing continue to threaten cleanroom processes and personnel, semiconductor cleanroom design must be able to address each one using: 

• Powerful HVAC systems
• Multi-stage filtration systems
• Anti-static and conductive materials
• Proper operator gowning and procedures
• Thorough and regular cleaning protocols

Contact Angstrom Technology for a Reliably Controlled Semiconductor Cleanroom

For a semiconductor cleanroom that eliminates all environmental threats, trust Angstrom Technology. Since 1989, our cleanroom experts have been designing, building, and installing high-quality cleanrooms for a variety of industry specialties and service areas. We’re now recognized as one of the top manufacturers of modular, turnkey cleanrooms in the country, and we’re continuing to expand services overseas as well. 

We can guide you through the design process and deliver the cleanroom solution you’ve been searching for. Contact us to get started today.