Technology

Plasma solutions

Plasma

Plasma is often called “the fourth state of matter,” along with solid, liquid and gas. Just as a liquid will boil, changing into a gas when energy is added, heating a gas will form a plasma – a soup of positively charged particles (ions) and negatively charged particles (electrons). Adding energy to create plasma out of a gas can also be realized by applying a strong electromagnetic field to the gas, this way generating ‘cold’ plasma. This type of plasma is used at nanoWatt.

Cleaning, etching and surface activation

Depending on the used process gases and depending on the surface to be treated, different plasma actions can be considered.

When performing plasma cleaning, surface contaminants are removed. This can happen either by chemical interaction of the plasma with the contaminant (very typical is the removal of hydrocarbon contamination by using an oxygen plasma) or by physical interaction. In the latter case, typically an inert gas like Ar is used as plasma gas, and Ar ions are ‘bombarding’ the contaminants on the surface. Think of it as sandblasting on an atomic scale. Typical applications are PCB desmearing and pre-treatment before (plasma)coating.

Plasma etching follows the same principle as plasma cleaning, only is it the substrate material itself which gets removed instead of a contaminant. Typical applications can be found in the semiconductor industry where silicon and glass get selectively etched.

Plasma activation or plasma functionalisation in its turn focuses on improving the surface wettability of various materials like PP, PMMA, PE, PET and PTFE. Plasma activation will reverse the polarity of plastic materials and allow the polymers to get new surface functionalities by increasing the surface tension on the treated materials' surface.

This way the surface gets prepared to ensure a good adhesion with adhesives, paints, inks, coatings and epoxies used in the next process step.

Typical applications can be found in medical plastics (cell culture dishes and flasks, microfluidics and lab-on-a-chip) as well as in a very broad industrial range where gluing, printing or coating on plastics is applied, like consumer electronics and automotive.

Clearly, these plasma actions can also happen at the same time in one process step. For instance, when choosing the right process gas and treatment parameters, a surface can get cleaned and functionalized at the same time.

Polymer coatings

Plasma polymerization is a method to directly deposit a very thin, soft but dense film on substrates. The plasma is formed by ionization of an organic monomer gas through an electrical discharge at high frequencies.

Plasma polymerization uses gaseous monomers which, excited by a plasma, react and precipitate onto two- or three-dimensional substrates as a polymer layer. Through the right choice of monomers (or precursors), plasma power input, pressure and deposition time, it is possible to control a number of properties of the deposited coating, such as chemical nature, density of functional groups, surface energy and contact angle.

These permanent coatings are extremely thin (typical 10 to 300nm) and flexible. They provide uniform coverage of complex three-dimensional surfaces and penetrate into the structure of the material being treated, while maintaining other physical properties (like air-permeability or acoustic behaviour)

This results in a wide scale of applications where these coatings are applied as:

  • Barrier coating (electrical or chemical)
  • Oleophobic coating
  • Hydrophobic coating
  • Hydrophilic coating
  • Anti-microbial coating
  • ….and many more

Several polymer coatings can be combined in a functional stack of coatings, tailored to a specific application.

Diamond-like Carbon (DLC) and Diamond-like Nanocomosite (DLN) coating

DLC and DLN coatings are also formed by use of a low-pressure plasma, but are extremely hard, a multiple of the hardness of steel. They are smooth & conformal coatings combining their high hardness with a low friction or low sticking behaviour. These coatings are composed of carbon & hydrogen, possibly boosted by one or more dopants (such as Si, F, O, N, W, Ti,..). They are mostly applied on steel parts, but also other metals, glass or plastics can get this kind of coatings.

Plasma hardware

nanoWatt designs and manufactures a wide range of low-pressure plasma equipment , specifically designed towards process type and materials to be treated.

All machines have the process and alarm functions controlled by a PLC. The operating screen (HMI) ranges from an economical yet comprehensive industrial 7” touchscreen to an industrial 17” touch screen PC which allows for extended functionalities towards datalogging, recipe management and customized integration into the ERP/MES system of the customer.

For plasma cleaning, etching and activation, there’s a very extended choice of machines to treat materials. The choice is determined by the size of the materials to be treated, the type of process and the volume of the parts that need processing.

For (3D) components, parts are often positioned in horizontal trays, which are driven into the treatment chamber. However, also vertical (hanging) loading and drum loading are offered, as well as jigs which are specifically designed towards the parts to be treated.

nanoWatt offers plasma equipment for plasma cleaning, activation and etching with vacuum chamber sizes ranging from 8 to over 3000 litre, going from basic small and economic standard systems to fully customized 24/7 production systems.

A specific range to consider are our roll-to-roll systems, which allow plasma cleaning, activation or etching of material wound on a roll. During the process, the material gets unwound, is guided through the plasma zone where the material gets treated and is then rewound onto another core. nanoWatt offers systems capable of handling rolls of 2 meter width and a diameter of 1 meter.

Plasma polymer processes can be complex and bring some more restrictions towards freedom of design. Still, also here nanoWatt offers a wide range of coating equipment. Horizontal and vertical loading, as well as specific jig design, is offered. Plasma polymer coating machines come in a treatment chamber size range of 200 up to 1000 litre.

Also for plasma polymer coating processes, nanoWatt offers roll-to-roll systems capable of treating rolls of 2 meter width and a diameter of 1 meter.

Diamond-like Carbon and Diamond-like Nanocomposite Coatings require very specific coating equipment. Therefore, only 1 size currently available of 1200 litre chamber volume. Smaller or larger possible upon request.

DLC- and DLN-coatings are not yet available in a roll-to-roll system.