PECVD (Plasma enhanced chemical vapor deposition)
Plasma
Plasma is considered the fourth state of matter. By adding energy matter can be transformed from solid to liquid, from liquid to gas and from gas to plasma.
In plasma the molecules are decomposed into a mixture of neutral and charged particles that interact with all exposed surfaces of the material. When the object is an open cell structure, the plasma particles will interact with the inner surface as well.
Low pressure versus atmospheric plasma technology
Plasma enhanced chemical vapor deposition (PECVD) is a chemical vapor deposition (CVD) process that uses cold plasma. It uses low deposition temperatures.
In low pressure plasma technology a stable and effective plasma is created by an electromagnetic discharge of a process gas at low pressure (and at low temperature). The process gas will be partially decomposed into radicals, electrons, photons and atoms, and will also be partially ionized. These reactive species interact with all exposed surfaces of the material. This interaction is both chemical and physical in nature. When a material has inner surfaces, the plasma will also penetrate that structure to interact with these inner surfaces.
In atmospheric plasma there are major differences.
Atmospheric plasma is a partially ionized gas that contains a mixture of ions, electrons, and neutral species. It is generated at atmospheric pressure and can be utilized for various surface treatments. Atmospheric plasma can be generated using different methods, including atmospheric pressure glow discharge.
History of low pressure plasma technology and PECVD
Plasma cleaning
Low pressure plasma technology has been industrially applied since the early eighties. Initially it was mainly used to clean or de-smear printed circuit boards, using an etching type of plasma; plasma cleaning.
Gradually the technology spread into rigid plastics’ industries. Polymers were cleaned and activated using pure gases such as oxygen and nitrogen.
The plasma cleaning removes organic contamination on microscopic level by breaking the longer chains of the dirt into shorter chains that are volatile and are pumped away in the plasma exhaust.
Activation
The activation creates functional groups onto the outer polymer chains of the material. These typically polar groups increase the surface energy of the plastic. This increase of energy improves the adhesion with paint, adhesives or printing ink, even on complex three dimensional parts.
This kind of functionalization of surfaces opened new markets for plasma technology: medical devices, automotive interior and exterior parts and consumer electronics. Different industrial markets adopted the low pressure plasma technology because of the higher quality performance and the ecologic and economic advantages. Plasma cleaning and activation is nowadays widely used to replace primers, flaming or corona.
Low pressure plasma cleaning and activation
PECVD in filtration
In the early nineties the filtration industry started using low pressure plasma technology (PECVD) to clean and activate the surface of filter media.
Plasma cleaning is a removal of organic contamination layers on microscopic scale.
Plasma activation is a chemical modification of the surface of the material. The effect is not permanent and will disappear over time. The shelf life is typically days to months depending on the application material.
Plasma activation only affects the outer molecular layers of the material. New chemical groups are added to the polymer chains and will increase the surface energy of the plastics. The higher surface energy is reflected in a lower water contact angle with water, which results in better wetting of the surface. Typical activation gases are O2, N2 or N2O, or gas mixtures such as N2H2. The choice of gas depends on the material and the subsequent application.
Plasma activation is often used as a pre-treatment step prior to gluing, plasma coating or chemical coating, of both flexible and rigid filter media.
Low pressure plasma activation is also well known in the production of rigid filter media made from porous plastics. With low pressure plasma technology PECVD the plasma can enter into the core of the porous structure.
PECVD in medical
In medical applications the highest standards are set. Uniform quality and performance is of utmost importance. The process needs to be validated and to be repeated consistently in the same way to achieve reliable results.
Plasmalex vacuum plasma technology cleaning, etching and activation processes increase the surface tension of medical materials, hence extend the lifespan of products. Nanocoatings add various properties into the core of complex and porous structures. They ensure tunable surface energy for a wide range of medical applications.
As there are: Activation prior to gluing for needle hubs, catheters, … Fine cleaning of stents, Intraocular lenses, implants and guidewires before coating or implanting.
Plasma coatings provide a range of benefits to different materials.
They increase the wettability of cell growth plates, facilitating cell attachment and growth.
Plasma coatings ensure low retention for pipette tips.
For printed circuit boards (PCBs), plasma coatings offer corrosion protection by forming a barrier against moisture. This can help to extend the lifespan and improve the reliability of electronic components.
Plasma coatings prevent water ingress for wearable devices.
Europlasma has an extensive active patent family protecting machine design, processes, methods for plasma deposition.
PECVD in electronics
Electronic customers want the highest performance and protection for their electronic products. Plasmalex, specialist in Plasma Enhanced Chemical Vapor Deposition, provides several solutions to improve end-product value.
The PECVD process is executed in a precisely controlled atmosphere. It assures a very consistent treatment of 3D complex shapes. With its plasma technologies, Plasmalex ensures best in class splash and waterproofprotection for your electronics with high quality nanocoatings for several electronical applications.
PlasmaGuard™ coatings provide splash-proof or waterproof moisture protection to devices such as wearables and consumer electronics. With these halogen free coatings, we combine the highest performance and protection for electronic products, with the lowest environmental footprint.
Plasmalex also offers cleaning and etching of PCB’s and connectors i.e. On top of applications in medical, electronics and filtration Plasmalex’ PECVD is providing a solution for many different applications where surface tension modifications are relevant.
Plasmalex’ company Europlasma started building roll-to-roll or reel-to-reel systems more than thirty years ago. This low pressure plasma equipment applies the same plasma activation processes to flexible materials. The first of this type was installed in the field in 1993. Since then an increasing number of producers have explored surface modification of industrial textiles by low pressure plasma.
Low pressure plasma functionalization with PECVD
In the late nineties low pressure plasma technology was improved to achieve polymerization of monomers on materials, depositing real nanocoatings on the surface, to add new and permanent functionalities to the material. Innovative plasma processes allow to deposit coatings with high levels of hydrophobicity and oleophobicity on rigid and flexible materials, which can be planar (2D) or complex shaped (3D). Other plasma processes have been developed to obtain the opposite effect by making substrates hydrophilic.
History of Nanoscale plasma coatingsBenefits of PECVD for surface treatment
Plasma technology for surface treatment solutions offers several benefits.
High precision
It ensures high precision surface plasma cleaning, activation and etching
Flexible process
The low process temperature allows for the handling of sensitive substrates and materials
Environmental friendly production process
One of the key drivers of PECVD is the reduced environmental impact compared to wet chemical processing.
Zero water consumption
Zero water consumption is made possible by using the monomers in their pure form.
Low chemical demand
All plasma processes, whether it is low pressure plasma activation, cleaning, functionalization or coating, are performed on a molecular scale, which demands very low amounts of chemicals.
Low energy consumption
Low pressure plasma needs only low energy consumption. Heating is limited and far below the heating requirements in wet chemical processing.
Table 4 shows the consumption of fluorochemicals, electricity and water for traditional wet chemical coating processes and low pressure plasma processes. Its shows figures for coating an annual production of 2 000 000 running meter textile roll-to-roll in mass production. The low pressure plasma coating deposited has a very high performance in durability against washing. It is obvious that when the requirements are lower, the coating process can take place at a higher speed, which will reduce the consumption of chemicals and electricity for a given running length.
2 mio running meters | Traditional DWR | Plasma DWR | Difference |
Fluorochemicals | 19 685 kg | 3 733 kg | – 80 % |
Electricity consumption | 1 066 667 kWh | 508 393 kWh | – 50 % |
Water consumption | 437 445 l | 0 | – 100 % |
Table 4: environmental comparison for low pressure plasma and traditional DWR
Reduced pressure
Low pressure plasma processes take place under reduced pressure. The system works in a controlled environment, where process parameters are easily controlled and monitored. The main parameters are flow, pressure, power and temperatures. The operator is not exposed to the reaction chemicals because of the closed system, highly reducing the risk for accidents. Low pressure plasma is thus a “clean” technology as well.
Plasma surface treatment is a powerful process that uses fewer chemicals, has a smaller environmental footprint than other surface treatments, and can be applied to almost any type of material in various industries.
Plasmalex specializes in Plasma Enhanced Chemical Vapor Deposition. It has a wide range of plasma treatment solutions will help you change surface characteristics at a microscopic (nanoscale) level to plasma clean, activate, etch and coat materials.
With plasma cleaning molecular contamination layers are removed from a surface
Plasma Etching removes surface material up to 1 µm
Plasma activation chemically modifies surface prior to gluing, painting or bonding
If surface properties are modified chemically via plasma polymerization, we talk about plasma coating.
(link naar plasma coating)
Europlasma has been developing, finetuning and delivering plasma surface treatment and coating solutions and the systems to apply these solutions for over 30 years
