Spreading of the nanofluid triple line in ink jet printed electronics tracks

One of the next avenues for Additive Manufacturing to develop is that of multi-material deposition in order to add functionality to the already complex geometries that are capable of being manufactured. However, for electronic applications the fidelity of the deposited electronic tracks is of utmost importance. The purpose of this study was to investigate the effects of solid surface tensions, σsg − σsl, on the quality of printed lines, using 30–40 nm silver nanofluid ink. The solid surface tensions of silver ink on glass and polytetrofluoroethylene (PTFE) substrates were determined theoretically, knowing characteristics of droplet. Meanwhile, a Dimatix printer with nozzles of size of 21.5 μm was used to print conductive lines on smooth glass and PTFE substrates. The printed lines on glass were observed to be continuous with high quality of triple line, which was attributed to the high solid surface tensions of silver nanofluid ink on glass substrates. The solid surface tensions of silver nanofluid ink were relatively low on PTFE, as results the printed lines were discontinuous. The solid surface tensions were introduced as a reliable criterion to predict the printability of nanofluids. The distribution of silver nanoparticles and layering phenomenon in silver nanofluid triple region on glass substrate was clearly observed, using environmental scanning electron microscopy (ESEM) for the first time. In addition to disjoining pressure, the size of droplet and affinity of nanofluid for substrate were observed to have important influences on spreading of nanoparticles in triple region.