Composite Layer Stamp for Microcontact Printing

Applications

This technology has applications in the printing industry generally, specifically in soft lithography; imprint and microcontact printing of molecular or fluid inks on flexible webs (e.g., printed electronics). The ability to produce stamps with layers of varying properties leverages a great set of sensing and actuating methods which allow for the precise, high resolution, continuous and cost-effective printing of displays, circuits, photovoltaics and other devices on flexible substrates.

Problem Addressed

In microcontact printing, selective contact between the substrate and the micro- or nano-scale features on the stamp results in transfer of a molecular or fluid ink.  The proposed layered stamp alter layer optical properties.  Transmission of UV light generates a high-contrast image of the printing zone, a region of conformal contact between the patterned stamp and the impression surface. The clear visibility of the contact areas allows continuous (in-line) inspection of the printing process, and hence greater active control capabilities to meet rapidly increasing resolution demands of micro / nano printed substrates.

Technology

The inventors developed a bi-/multi-layer PDMS (silicone) soft-lithography stamp. One layer is either chemically modified or doped with fluorescent particles or dye, so that functional groups, molecules or particles provide different optical or electrical properties. This stamp is used for microcontact printing. The stamp is produced by an additive manufacturing fashion, casting layers on top of each other. Each layer is entirely or partially crosslinked by the time the next layer is cast. The stamp material is cast into a centrifuge to create a seamless cylindrical stamp. To create the mold on the inner surface of the centrifuge, two layers of photoresistive polymer are applied to it: a fully-covering coat for creating a planar surface and a laser-structured layer that provides the pattern. The technique of varying optical properties allows for new methods of continuous inspection and control of the printing process. Other functional properties can be introduced to the layers with regard to applications in advanced metrology and contact control; such layers could provide for various sensing, actuating or thermal control purposes.

Advantages

  • Low-cost stamp
  • Few moving parts with more range of flexibility
  • Varied optical properties of layers allows for new methods of control and inspection during printing process