Infrared for Printed Electronics Applications

Infrared for Printed Electronics Applications

Printed functional materials need intelligent solutions for print drying and sintering. For this purpose, a new infrared tool for post-treatment of roll-to-roll printed functionalities was qualified. Numerous experiments with different printing techniques and test setups were carried out to obtain optimal drying and sintering process results. All experiments were supported by advanced numerical simulations.

Ray Tracing calculations were used for optimizing the setup geometry and to achieve the infrared power density on the substrate surface needed for a specific process. The figure at left shows a process area split into a drying zone generated by an emitter power density of 50 kW/m2, and a sintering zone with an emitter power density of 150 kW/m2.

For ink-jet tests the nano ink Jet Silver U5603 (Suntronic) was printed on PEN foil (175 µm thick) using a Dimetix DMP-2831 printer. Samples were dried and sintered in one R2R process step with a web speed of 60 m/min. Using the tailored Heraeus infrared tool with an emitter power density of 220 kW/m2.

Inks, Printing Techniques and Substrates Using IR Technology

The table gives an overview of all combinations of inks, printing techniques and substrates successfully processed so far using Heraeus infrared technology. This includes a dielectric material usually cured by UV light. By adjusting the parameters of the infrared tool, optimal drying and sintering conditions for all combinations were achieved:

  • Infrared power density in the range between 20 to 220 kW/m2
  • Peak emission wavelength varied between 0.9 and 2.0 µm (corresponding to emitter filament temperatures 1200°C to 3000°C)
  • IR drying and sintering was determined with a web speed of 60 m/min., demonstrating the suitability of this method for mass production
Printed Technology Ink (Supplier) Substrate Web Speed (M/min.) Infrared Power Density (kW30/m2)
Screen PEDOT PSS (Heraeus Clevios) PET 3.8 30
Rotative Screen Ag Polymer (Heraeus) PET 3 25
Ink Jet Au Resinate (Heraeus) Glass 0.2 100
Nano Ag PET 3 120
60 220
14 100

Dielectric (Polytronica)
PEN 3 115
Gravure PET 60 80
Flexo PET 20 80
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