Conductive Layers on a Shrinkable PET Film by Flexographic Printing

Area of Science:

• Materials Science
• Printing Technology
• Nanotechnology

Background:

• Flexographic printing on heat-shrinkable substrates is challenging due to dimensional changes during thermal processes.
• Electrically conductive inks are crucial for creating functional electronic components on flexible materials.

Purpose of the Study:

• To evaluate the suitability of six commercial conductive inks (silver, copper, graphite nanoparticles) for flexographic printing on heat-shrinkable PET films.
• To assess the impact of anilox line screens on printability and ink performance.
• To analyze the electrical conductivity and adhesion of printed inks before and after substrate shrinkage.

Main Methods:

• Selection and testing of six commercially available conductive inks (silver, copper, graphite nanoparticle-based).
• Flexographic printing on a one-direction heat-shrinkable PET film (78% maximum shrinkage) using three different anilox line screens.
• Evaluation of printability through rheological tests.
• Assessment of ink adhesion to the PET substrate.
• Measurement of electrical conductivity of printed paths prior to and post-shrinkage.

Main Results:

• Printability and adhesion varied significantly among the tested conductive inks.
• Electrical conductivity of printed paths was affected by the substrate's heat shrinkage.
• The choice of anilox line screen influenced the quality of the printed conductive traces.

Conclusions:

• The study highlights the critical interplay between ink formulation, printing parameters, and substrate properties for successful conductive flexographic printing.
• Optimizing ink selection and printing conditions is essential to maintain electrical performance after heat shrinkage.
• Further research is needed to develop inks with enhanced adhesion and stable conductivity on dimensionally unstable substrates.