Architected Porous Media for Metered Liquid Transfer Flexographic Printing

Michael Gallegos1, Chelsea Garcia2, Ethan Secor1, Bryan Kaehr1,2

  1. Sandia National Laboratories
  2. University of New Mexico

Many mass production printing processes are being re-examined to determine their suitability for the emerging area of printed electronics. Among these include roll-to roll processes such as flexography, gravure and offset—all of which rely on high speed ink-transfer mechanisms using direct print-form to substrate contact. Here we examine the flexography technique (flexo) which uses inked relief structures (e.g., rubber stamps) for pattern printing. To address many of the defects that plague the flexo process for printed circuits, we considered how an engineered porous stamp could increase print fidelity and film uniformity. We hypothesized that architected stamps saturated with ink could deliver metered deposition to a substrate via a mechanical metamaterial response (e.g., negative Poisson’s ratio) during compression. Using an ultra-high resolution 3D printing technique, we fabricated porous stamps with micro-scale features and compared their performance to solid stamps. We found that simple fiber-based porous stamps consistently delivered thinner and more uniform films versus solid counterparts. Investigations using compression-enabled mechanical structures (metamaterials) lead us to reconsider the greater effects of liftoff versus contact during printing. With this in hand we designed an experiment to begin to understand competing forces (capillary pressure in the stamp versus contact meniscus) resulting in significant control over fluid transfer by varying the pore gradient. Overall, this work lays a foundation to understand the fluid mechanics and develop advanced flexographic transfer processes using free-form microfabrication of porous media.

Sandia National Laboratories is a multi-mission laboratory managed and operated by National Technology and Engineering Solutions of Sandia, LLC., a wholly owned subsidiary of Honeywell International, Inc., for the U.S. Department of Energy’s National Nuclear Security Administration under contract DE-NA0003525.