The effect of the ink composition on the performance of carbon-based conductive screen printing inks

Abstract

Conductive carbon-based screen printable inks are used in a wide range of applications. The aim of the comprehensive study was to monitor how the fundamental components affect the ink performance. In the present work there were prepared several variants of carbon-based inks. The higher ratio of carbon black in the graphite (G):carbon black (CB) mixture, and also the higher total carbon amount have been confirmed to cause an increase in viscosity in the shear rates range from 200 to 1000 s⁻¹. The lowest sheet resistance values were observed with 3:1 G:CB ratio. Increasing of the total carbon amount from 15 to 35 wt% has led to improvement in conductivity with final value of 32.4 Ω sq⁻¹. The increasing ratio of lower boiling point solvents (4-hydroxy-4-methyl-2-pentanone, ethyl alcohol) has led to the improvement of the sheet resistance (lowest value of 22.73 Ω sq⁻¹), while the roughness values increased. In the case of rheological properties evaluation, the ethyl cellulose content modification (increase from 2 to 10 wt% in the binder) resulted in increasing viscosity dependencies. In addition, the increase of the ethyl cellulose content had minimal impact on the roughness, but positive impact on the conductivity. On the other hand, it was identified an unobvious trend after modifying the binder by polyvinylpyrrolidone. To achieve the desired effect on the sheet resistance, volume resistivity and roughness of the printed layers it is necessary to specify the most proper ethyl cellulose:polyvinylpyrrolidone ratio. The main reason is the interaction between the two polymers within the binder.