Dry Printing of Ag–Ni Conductive Particles Using Toner-Type Printed Electronics

Abstract

Printed electronics are a set of additive manufacturing methods for creating future flexible electronics on thin polymeric sheets. We proposed the toner-type, dry, page-printing of Ag–Ni composite conductive particles on flexible plastic sheets without pre-treatment. No chemical solvents are necessary to compose the inks of the electronic materials used for the toner-type printing, and no chemical treatment is required for the plastic film substrate surface. In addition, multilayer printing is simple when using toner printing because previously printed materials do not need to be resolved; furthermore, composing the thick films of the electronic materials is relatively simple. In this study, we fabricated an Ag–Ni composite toner to improve the fluidity of the toner particles compared to bare Ag particles. We successfully printed IC peripheral circuits at a resolution of 0.20 mm and demonstrated that the actual electrical circuit pattern can be formed using our method.

High-Resolution Printing of Various Electronic Materials by Electrophotography

“…Figure 1a shows the developer consisting of Ag nanoparticles (NPs) and carrier particles [85,86]. The carrier particle comprises the ferrite material and has a role in generating electrical charge in the toner particle by frictional charging and by prohibiting natural aggregation of the toner particle.…”

“…The dark gray particles include approximately 10% Ag NPs and 90% carrier particles by weight, and the mixed powder had sufficient fluidity for the developer particles. The fluidity of the developer particles is essential for drawing high-resolution electronic circuits, which are evaluated using the repose angle [85]. Figure 1b shows the SEM image of the developer.…”

“…The absence of solvent completely suppressed the exhaustion of volatile organic compounds (VOCs). No VOC emissions are preferred when electronic fabrication is replaced with a direct printing process [84][85][86][87].…”

“…In several studies, we fabricated organic field effect transistors [86,87] and macro-scale electrical circuits [85]. In this study, we fabricated simple elements inside small-scale ICs using various electronic materials such as metals, transparent conductors, carbon materials, oxide semiconductors, organic semiconductors, polymer insulators, and inorganic insulators.…”

Dry Printing Pure Copper with High Conductivity and Adhesion for Flexible Electronics

“…The second challenge is that achieving low resistivity and long-term stability of ink-based printed Cu lines is extremely difficult since Cu easily oxidizes into copper oxide (CuO) and cuprous oxide (Cu 2 O) when exposed to the air. − Some studies have suggested the use of stabilizing agents such as polyvinylpyrrolidone (PVP) in synthesizing Cu nanoparticles (CuNPs) to protect them from oxidation. − Additionally, while electronics printing on-demand in rugged environments can be used for lunar surface and deep space exploration missions, many inks have stability concerns such as short shelf lives, intolerance to vibrations, or variable G loads and need to be stored at a low temperature and then printed at higher temperatures. Finally, the use of environmentally unfriendly chemicals in inks, the highly tailored ink formulation requirements that are demanding in terms of time and cost, the inherent ink instabilities, and the required postprocessing thermal treatments to remove solvents/additives have all driven the need for alternative dry printing technologies. ,− To address these challenges, we have recently developed a novel additive nanomanufacturing (ANM) technique that allows on-demand nanoparticle generation by in situ laser ablation and real-time laser sintering processes. ,− …”