Plasma printing

Under atmospheric pressure, plasma can be produced even in very small volumes with dimensions of just a few micrometers so that the local functionalization of surfaces is possible. Plasma printing is an innovative process for the local modification of surfaces: a structured dielectric forms cavities in which the plasma develops. The typical dimensions of the cavities are from a few tens to a few hundred μm. In addition to the position-specific modification of surfaces, this process also supports structured layer precipitation and functionalization. Numerous functional groups can be impressed on the substrate, similar to a stamp, depending on the chosen to discharge conditions. Suitable substrates include polymers, glass and silicon. Surfaces with any geometries such as arrays of spots, with special surface characteristics such as hydrophilic or hydrophobic properties, or with targeted chemical functionalization can be produced using the plasma printing process.

Local functionalization can be applied for example in the production of surfaces for biomedical applications (biochips, DNA/protein/diagnostic chips) and for subsequent metallization, among other things for the production of interconnect devices, RFID antennas or biosensors. Plasma printing can be realized in a discontinuous or a continuous reel-to-reel process.

Reel-to-reel plasma printing

© Photo Fraunhofer IST, Falko Oldenburg

Schematic illustration of the reel-to-reel plasma printing process.

At the Fraunhofer IST the plasma printing process has been further developed to the point where continuous coating from reel to reel is possible. This application has already been used successfully for manufacturing RFID antennas and biosensors.  

The two core components of reel-to-reel plasma printing are a high-voltage electrode, which is sheathed in an isolating material – the so-called dielectric – and as counterelectrode an engraved metallic print roller, as known from conventional rotogravure.

During plasma treatment the print roller rotates and the polymer film is pressed by the high-voltage electrode against the roller surface. As the film passes over the recesses of the roller structures, gas-filled cavities are created within which the plasma can be ignited (cf. opposite figure). In this way the print image on the roller can be transferred to the film as an area-selective modification. The process gases are routed into the plasma zone via a gas-nozzle system which is located just before the point where the engraved roller comes into contact with the polymer film. The type of surface functionalization can be selectively controlled via the composition of the process gas. 

Applications

Potential areas of application for the plasma printing technology include the manufacturing processes for products such as

  • flexible printed circuits,
  • radio frequency identification (RFID) antennas,
  • biosensors, 
  • displays, and
  • printed electronics.

Our offer

Production of structured samples – with or without metallization – for application tests at the customer

  • Contract research
  • Design and development of research systems to customer specifications
  • Process development
  • Development of production installations in technology transfer
  • Licensing

Technical Data

Substrate materials used to date polymer film made of PE, PP, PET, PEN, PI, PEEK
Minimum resolution in printing 25 µm
Throughput speed tested up to 10 m / min
Width of treatment tested up to 450 mm
Process gases dependent on the type of surface modification desired, for example, air, nitrogen, argon, admixtures of other gases (CO2, N2O, H2)
Stability dependent on substrate and plasma parameter, currently > 1 year