1
Infra-red curing methodology for Roll-to-Roll (R2R) manufacturing of conductive
electrodes through inkjet technology applicable for devices in the field of flexible
electronics
Kalyan Yoti Mitra
1
, Dana Weise
1
, Melinda Hartwig
1
, Reinhard. R. Baumann
1, 2
1
Technische Universität Chemnitz, Digital Printing and Imaging Technology, Chemnitz,
Germany
2
Fraunhofer Institute for Electronic Nano Systems (ENAS), Printed Functionalities, Chemnitz,
Germany
ABSTRACT
The Inkjet printing technology is a direct patterning technique to deposit functional
materials with high precision and accuracy. This deposition technology is often used to
manufacture conductive electrodes for different active and passive electronic devices on flexible
foils. It is an up-scalable process in terms of printing devices from low (via. Sheet-to-Sheet, S2S
platform) to high (via. Roll-to-Roll platform) quantities. For manufacturing of these conductive
electrodes and hence electronic devices through the R2R platform, a suitable post-
treatment/curing methodology is very much desired. In this work, the focus is concentrated on
the curing methodology using the Infra-red radiation for both the inkjet-printed conductive
electrodes and insulator layer, for completing a “proof of concept” Metal-Insulator-Metal (MIM)
electronic device structure over the R2R platform. A conductive silver nano-particle and a
polymeric dielectric ink are used to print the top and bottom conductive electrodes, with a middle
insulator layer for the MIM structure respectively. It is observed that not only the printed silver
electrode layers (both top and bottom) can be cured with the help of the Infra-red radiation, but
also the insulator layer. Additionally, the layers constituting the MIM device structure is cured
with the conventional curing methodology which in this case is thermal curing using a
convection oven. This curing procedure for the printed functional layers is generally performed
for the S2S manufacturing process. The conductive electrodes are then electrically characterized
by measuring the sheet resistance (on the foil and dielectric layer) as a function of the un-
conventional Infra-red radiation and conventional oven curing methodologies. The cured layers
for both the conductive electrodes and insulator layers are morphologically analyzed for the layer
thickness and homogeneity. The electrical performance of the cured insulator in form of the
obtained capacitance from the MIM passive device is compared for the two mentioned curing
methodologies.
INTRODUCTION
During the recent years, reports about the all inkjet-printed thin-film-transistors (TFTs)
are found in numerous publications. [1] Although these reported TFTs are fabricated using
different architecture stacks, but they still require the same fundamental electronic layers e.g.
conductive source, drain and gate electrodes; insulating dielectric; and semiconductor.
Especially, MIM capacitors which are the basic building block required to fabricate bottom gate
architecture TFTs. In most of the cases the output quantities and the success rate from the
Mater. Res. Soc. Symp. Proc. Vol. 1791 © 2015 Materials Research Society
DOI: 10.1557/opl.2015.533