Printing Process of Electrically Conductive Silver on Heat Transfer Polymer Substrates for Wearable Electronics Applications

Abstract

Most of textile substrates are porous because they are fabricated from yarns by weaving, or knitting. Hence direct printing of electrically conductive ink to form solid patterns on textile fabrics is a challenge. One of the conductive circuitry forming methods includes the usage of the heat transfer polymer (HTP) substrate. In this study, we investigate the described fabrication process which includes the printing of electrically conductive silver ink on the HTP substrate for wearable electronics applications. The printing process on the HTP substrate using screen printing was empirically studied using our newly developed roll-to-roll pilot line for flexible hybrid electronics. The investigated materials included $60\mu \mathrm{m}$ thick HTP substrates, and a shear thinning silver ink. The test vehicles includes lenticular patterns from 200 to $700\mu \mathrm{m}$. The results of the study show that the different line-widths towards the resistivity values of the same length printed silver patterns follow a power function equation. The study also finds that the average electrical resistance values of the printed silver on the HTP substrate are 17.3% lower than those of on the polyethylene terephthalate (PET) substrate.