Effects of different thermal sintering temperatures on pattern resistivity of printed silver ink with multiple particle sizes

Resistivity is considered a significant parameter for printing a conductive pattern and nano-ink. Nevertheless, the resistivity of a sintered printing pattern varies with the performance of the pattern and nano-ink. The cross section or non-uniformity of the printing pattern is not taken into consideration, and the changes in resistivity are not measured during the whole sintering process. In this work, the cross section uniformity of the pattern is improved, which is attributable to the standard sample template fabricated by laser engraving. First, the ink containing 50 wt. % silver nanoparticles (AgNPs) with sizes ranging from 30 to 100 nm was prepared. Second, the prepared ink and commercial ink containing 50 wt. % AgNPs with an average size of 5 nm were separately injected into two standard sample templates. Finally, a four-probe platform was employed to carry out the sintering process at different temperatures. We studied the effects of sintering temperature on pattern resistivity and the subsequent performance of the prepared ink. Furthermore, the thermal conductivities of inks were calculated through the optimized Wiedemann–Franz law for different temperatures. The results showed that electrical resistivity of two inks changed after sintering, presenting the same trend of an initial linear increase, then a linear decrease, followed by a period of stability, and finally a linear increase as the sintering temperature increased. In addition, when the ink was sintered completely, the porosity observed using an optical microscope with 1000× magnification and resistivity and thermal conductivity of the prepared ink were 80.13%, 69.48%, and 66% smaller than those of commercial ink, respectively. The methods proposed in this paper lay the foundation for further research on nano-ink.