دانلود رایگان مقاله انگلیسی توسعه خط سه گانه نانو سیال در خطوط جوهر افشان چاپی الکترونیک - نشریه الزویر

abstract 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, sg − sl, 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 m 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.

5. Results and discussion

5.1. Calculation of solid surface tension and prediction of droplet shape The silver ink droplet shape on a smooth substrate was captured using the Drop Shape Analysis System DSA100. Knowing the characteristics of a droplet, Eq. (9) was solved to predict the asymptotic contact angle, s. Having the asymptotic contact angle and liquidgas surface tension, the solid surface tensions could be calculated from Eq.(8). The solid surface tensions for glass and PTFE substrates were hence determined to be 0.0228 N/m and 0.0043 N/m respectively for the silver ink used. The experimental uncertainty for the measurement of solid surface tensions was estimated to be less than 6%. The solid surface tensions value for the PTFE substrate is relatively low and consequently the silver ink demonstrated poor wettability of the PTFE, resulting in a series of disconnected droplets, as shown in Fig. 4(a). In contrast the relatively high solid surface tensions value with the glass substrate resulted in high wettability of the silver ink, as shown in Fig. 4(b). Fig. 5 compares the experimental data with predicted droplet shape. The latter obtained from solving the system of ordinary differential Eqs.(2)–(5) along with Eq.(9) and the boundary conditions given by Eq. (7), knowing only the droplet volume and physical properties. The percentage of absolute errors between theoretical prediction and experimental data for points 1–8 respectively were 0.79, 0.01, 0.67, 0.49, 0.38, 0.67, 0.61 and 0.4. Point 8 has maximum radius of triple line. The good agreement between experimental data and theoretical prediction indicates the accuracy of Eq. (9).