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

ABSTRACTThe 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.