In this article, you’ll learn everything you need to know about plasma cleaning, how it works, and its practical applications. Read on for informative answers to frequently asked questions.
Plasma Cleaning Definition – What Is It?
Plasma cleaning, also known as ultra-fine cleaning or surface treatment technology, is a dry, physicochemical cleaning process that removes organic contaminants and the finest residues (in the nanometer range) from surfaces.
Plasma cleaning is necessary when surfaces must meet the highest purity requirements and wet chemical processes are insufficient or should be avoided.
As a result, this precise, efficient, and environmentally friendly surface cleaning process is frequently used in industrial manufacturing and medical technology. Plasma cleaning technology is particularly advantageous for industries that perform high-precision processes (e.g., bonding, coating, or assembly).
What does plasma cleaning remove?
Plasma cleaning removes organic contaminants (carbon-containing compounds) as well as inorganic contaminants (non-carbon-containing compounds). Classic examples include dust, salts, fine particles or residues, thin oil films, release agents, or greases. The cleaning process is also frequently used for sterilization or disinfection—that is, the efficient removal of germs, bacteria, or viruses.
What materials is it suitable for?
Plasma cleaning is not suitable for all materials. First of all, they must be able to withstand the vacuum. Materials that contain a high proportion of volatile components, such as water, can be very difficult or even impossible to clean.
Closed-cell foams can be damaged in a vacuum. However, the list of materials that can be cleaned is long and ranges from plastics, glass, and metals to ceramics. Please feel free to contact us for further details.
Plasma Cleaning Process and How It Works
The low-pressure plasma cleaning process is a contactless, high-precision, dry micro-cleaning method for surfaces using plasma (ionized gas). The low-pressure plasma, also known as vacuum plasma, is technically generated in a vacuum chamber. Three main mechanisms are at work in the chamber to ensure optimal performance: chemical cleaning, physical cleaning, and combustion.
Chemical Cleaning
The process gas in the cleaning chamber is excited by a plasma generator operating at a specific frequency. The resulting radicals and ionized particles react with the contamination on the product’s surface. This produces H₂O and CO₂. The environment in the production area remains unaffected by the process—for example, no ozone is produced, as can be the case with atmospheric plasma.
Physical Cleaning
The molecules of the process gas are accelerated by the frequency field. In the process, they strike the product to be cleaned. The high atomic mass causes a kind of micro-sandblasting. The contaminants are removed mechanically.
Combustion – High-Temperature Cleaning
Special conditions are created inside the plasma system’s chamber to generate heat within the product being cleaned. This promotes the outgassing of volatile substances, which polymerize on the surface and can then be removed. A rarely discussed but highly effective process.
Conversely, controlling the conditions during plasma cleaning prevents the product from heating up and discoloring. This applies particularly to conductive materials. Combinations of chemical and physical plasma cleaning can be extremely effective.
Through the use of physical cleaning or ablation, the bonds of contaminants are broken, which are then chemically removed via the gas phase. An interesting side effect is the fact that ionized particles in the plasma chamber dissipate static charges, which facilitates the removal of particles.
Advantages and Disadvantages of Plasma Cleaning
The main advantages of plasma cleaning lie in its precision, environmental friendliness, and efficiency. Commonly cited disadvantages include the high investment and operating costs (of the equipment) or the fact that not all materials can be cleaned using this method.
Advantages
The most important advantages of plasma applications and plasma surface treatments are:
- Highly effective ultra-fine cleaning at the nanometer scale, even for complex geometries.
- No drying process, which means treated materials can be processed immediately.
- Increase or activation of surface energy for optimal adhesion and wettability.
- No environmental impact, e.g., from toxic chemicals or harmful liquid waste.
- Particularly advantageous for the semiconductor/electronics industry, medical technology, and research (among many others).
Disadvantages
When innovative low-pressure plasma systems, such as those from plasma technology, are used properly, there are few disadvantages compared to conventional cleaning methods. Nevertheless, we will address the common concerns that often arise.
- High costs for purchase and subsequent maintenance
–> To address this, we offer high-quality, durable low-pressure plasma systems that we design specifically for your needs. We also offer cost-effective outsourcing of your plasma applications or our advantageous rental systems. - Material changes, such as deformation or surface roughening
–> We have cleaned everything from fine powders and even tiny diamonds to large components and rolls of material without observing any adverse effects. - No deep cleaning, because plasma only acts where it strikes
–> Our large chambers, with a volume of 8,000 liters, provide ample space, and our modular plasma generators ensure that the power is evenly distributed throughout the system. Low-pressure plasma thus cleans even the smallest cracks and cavities.
For any questions or concerns, we offer expert advice that is both competent and transparent at any time. We’ll tell you exactly what’s possible and will also honestly point out when a plasma application is less suitable.
Comparison to Conventional Wet Chemical Cleaning
Conventional cleaning methods (using wet chemicals) remove dirt and contaminants using liquids such as solvents, acids, or aqueous cleaners. As a result, components and material surfaces must be allowed to dry afterward.
Compared to conventional cleaning methods, plasma cleaning is a dry process for the precise, ultra-fine cleaning of material surfaces using ionized gas (plasma). In this process, molecules on the surface are effectively oxidized, sandblasted, or bonded.
Difference Between Low-Pressure Plasma and Atmospheric Plasma
Low-pressure plasma (ionized gas) is generated in a vacuum chamber, which is why it is also called vacuum plasma. It is ideal for activating, cleaning, coating, and etching surfaces and components—even those with complex 3D geometries.
- The wide range of contaminants that can be removed.
- Simplified control and repeatability due to fewer parameters.
- The cleaning medium is gaseous and the cleaning process is dry.
- No need to monitor wet chemical cleaning and washing liquids.
- There is no need to dispose of environmentally harmful wet chemical liquids.
Atmospheric plasma is generated at normal pressure and without a vacuum chamber, which is why it is also called atmospheric pressure plasma (APP) or APSA (Atmospheric Plasma Soft Ablation). The ionized gas is produced at normal pressure (ambient air) by applying electrical energy.
Compared to ND plasma, complex 3D geometries or deep cleaning treatments are not possible. Other differences include:
- The atmosphere in the chamber remains constant, thereby preventing recontamination.
- The gas flow rate is in the range of a few milliliters per minute and is therefore not a significant cost factor.
- In most cases, ambient air can be used as the process gas. This results in no costs whatsoever.
- Due to the low pressure in the chamber, there is no risk of fire or explosion when reactive gases such as hydrogen or oxygen are used.
- The exhaust gases contain no ozone, and no active exhaust system is required.
Conclusion
Plasma cleaning is a dry, precision cleaning process that does not involve environmentally harmful wet chemicals. This efficient cleaning method is suitable for many components and material surfaces in the semiconductor, electronics, and automotive industries, as well as for the medical technology and textile sectors. A plasma application for components and surfaces is also advantageous when the highest degree of purity or surface activation is required.
Low-pressure plasma, also known as vacuum plasma, in particular, offers the possibility of treating complex 3D geometries (not possible with atmospheric pressure plasma), internal surfaces, or bulk materials, and achieves fine and uniform cleaning results. For cost-effective operation of low-pressure plasma systems, the leading plasma system manufacturer (plasma technology) offers efficient solutions with comprehensive customer service.