Combined Inkjet Printing and Infrared Sintering of Silver Nanoparticles using a Swathe-by-Swathe and Layer-by-Layer Approach for 3-Dimensional Structures

Abstract

Despite the advancement of additive manufacturing (AM)/3-dimensional (3D) printing, single-step fabrication of multifunctional parts using AM is limited. With the view of enabling multifunctional AM (MFAM), in this study, sintering of metal nanoparticles was performed to obtain conductivity for continuous line inkjet printing of electronics. This was achieved using a bespoke three-dimensional (3D) inkjet-printing machine, JETx, capable of printing a range of materials and utilizing different post processing procedures to print multilayered 3D structures in a single manufacturing step. Multiple layers of silver were printed from an ink containing silver nanoparticles (AgNPs) and infrared sintered using a swathe-by-swathe (SS) and layer-by-layer sintering (LS) regime. The differences in the heat profile for the SS and LS was observed to influence the coalescence of the AgNPs. Void percentage of both SS and LS samples was higher toward the top layer than the bottom layer due to relatively less IR exposure in the top than the bottom. The results depicted a homogeneous microstructure for LS of AgNPs and showed less deformation compared to the SS. Electrical resistivity of the LS tracks (13.6 ± 1 μΩ cm) was lower than the SS tracks (22.5 ± 1 μΩ cm). This study recommends the use of LS method to sinter the AgNPs to obtain a conductive track in 25% less time than SS method for MFAM.

Printing Conductive Nanomaterials for Flexible and Stretchable Electronics: A Review of Materials, Processes, and Applications

“…Multiple layers of AgNPs were inkjet printed and IR sintered. Two distinct IR sintering methods, swathe‐by‐swathe and layer‐by‐layer, were employed to sinter the AgNP patterns to form conductive 3D structures …”

Printable Materials for the Realization of High Performance RF Components: Challenges and Opportunities

“…The characteristics of the print may be altered by changing the overlap percentage or the print direction [31]. The spacing must be less than 65% overlap [32] in order to prevent bulging of the printed line, and the ultimate resolution is a function of the droplet diameter as well as the spreading upon contact with the substrate surface [19,31,33]. Currently, the smallest achievable feature sizes of 25-50 μm are comparable to or even better than processes such as screen printing and photolithography [33].…”

Gravure Printing of Water-based Silver Nanowire ink on Plastic Substrate for Flexible Electronics

“…Printed electronics has drawn tremendous interest in the past few decades 1 – 6 , as it offers an attractive alternative to conventional silicon-based fabrication technologies by enabling low-cost, large-area, flexible devices for many applications such as energy storage 7 , thin film transistor 8 , light-emitting diodes 9 and wearable sensors for health monitoring 10 . Central to this technology are high-performance functional inks and high-throughput printing methods, such as screen 11 – 15 , inkjet 16 – 18 , gravure 19 , 20 and flexographic printing 21 . Among the existing printing methods, gravure printing, which utilizes direct transfer of functional inks through physical contact of engraved structures with a substrate, is a promising option for large-scale applications due to its high-speed, high-resolution deposition of functional materials and compatibility with roll-to-roll processes.…”