Suitability of Paper-Based Substrates for Printed Electronics.

Elina Jansson,Panu Tanninen,Kirsi Immonen,Ville Leminen,Liisa Hakola,Kim Eiroma,Johanna Lyytikäinen

doi:10.3390/ma15030957

Abstract

Flexible plastic substrates are widely used in printed electronics; however, they cause major climate impacts and pose sustainability challenges. In recent years, paper-based electronics has been studied to increase the recyclability and sustainability of printed electronics. The aim of this paper is to analyze the printability and performance of metal conductor layers on different paper-based substrates using both flexography and screen printing and to compare the achieved performance with that of plastic foils. In addition, the re-pulpability potential of the used paper-based substrates is evaluated. As compared to the common polyethylene terephthalate (PET) substrate, the layer conductivity on paper-based substrates was found to be improved with both the printing methods without having a large influence on the detail rendering. This means that a certain surface roughness and porosity is needed for the improved ink transfer and optimum ink behavior on the surface of the substrate. In the case of uncoated paper-based substrates, the conductivity and print quality decreased by preventing the formation of the proper and intimate ink-substrate contact during the ink transfer. Finally, the re-pulpability trials together with layer quality analysis detected very good, coated substrate candidates for paper-based printed electronics competing with or even outperforming the print quality on the reference PET foil.

Highlights

The demand for a variety of flexible electronics, such as wearable electronics, optoelectronics, flexible printed circuits, hybrid circuits, energy devices, and sensors, has been increasing rapidly in recent years
All the paper-based substrates used in this study have significantly higher roughness than the reference substrate polyethylene terephthalate (PET), predicting differences in the ink transfer, printability, and performance of the conductor lines between the selected substrate types
Some layer roughness and porosity was found to be beneficial for ink transfer and formation of highly conductive layers

Summary

Introduction

The demand for a variety of flexible electronics, such as wearable electronics, optoelectronics, flexible printed circuits, hybrid circuits, energy devices, and sensors, has been increasing rapidly in recent years. The situation in printed electronics is challenging from an environmental perspective due to commonly used plastic substrates, such as polyethylene terephthalate (PET) or polyethylene naphthalate (PEN), and metal inks, such as silver and copper. The main sources of climate impacts and sustainability challenges in the printed electronics stem from fossil-based substrate materials and metals used [2,3]. Bio-based flexible substrates, such as papers and paperboards, with smaller environmental footprint and originating from renewable resources are clear opportunities to improve the situation. Many of these materials are often recyclable and biodegradable

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