Plasma-activated copper-alkanolamine precursor paste for printed flexible antenna: formulation, mechanism, and performance evaluation†

Abstract

Copper-based pastes have attracted significant attention for printed electronic applications because of their low cost and high conductivity. Copper precursor pastes are easier to prepare, exhibit long-term stability and do not have oxidation issues during preparation and storage, when compared to copper micro-sized flakes and nanoparticle pastes. Up to now, copper precursor pastes activated by plasma have been rarely studied, and their activation mechanism is not clear. Furthermore, little attention has been paid to the application of these pastes in wireless electronic devices. In this paper, therefore, we formulated a plasma-activated copper–alkanolamine complex precursor paste for antenna applications. The paste was formulated only using copper(II) formate and excess 2-amino-2-methyl-1,2-propanediamine, which exhibited favorable flowability for screen printing. Copper films with good conductivity were produced on PET substrates by plasma sintering this paste. The effects of plasma sintering time on the properties of the copper film were explored and correlations between them were established. A possible plasma activation mechanism was proposed. Finally, a flexible ultra-wideband antenna with notch properties was fabricated with the copper paste, demonstrating its feasibility in wireless electronics applications.