Digital fineline printing is one of the most important developments in additive electronics. Inkjet itself has come very far with excellent progress even towards R2R industrialization. However, inkjet has two limitations as a technology: (1) limited resolution and (2) limited ink viscosity range. Here, we highly two technologies that can overcome these limits
Here we highloght the microdispensing technology developed by XTPL with nozzle diameters in the range of 0.5-12um. It demonstrates a unique combination of ultrafine line (few micron) 'digital' printing on flat and non-flat surfaces AND highly conducting (4p% Ag bulk?) highly viscous nanoparticle (Ag, Cu, Au) pastes. Thus, this technology advances the art not just by extenting the resolution of digital printing beyond what inkjet achieves but also by enabling far more conductive and highly loaded conductive pastes.
The innovation here is not just the microdispensing machine, but also the unique non-Newotonian highly-loaded nanoparticle pastes. The AgNP pastes have high loading (>85 wt% in some cases), small particles (45nm), and are in ethylene glycol solvents. The pastes require relatively high sintering temperatures (250-300C) but offer high conductivity, e.g., 4.2 uOhm.cm for the ink with 80wt% loading.
In the first slide below you can learn about the microdispensing machine itself. It currently has a substrate size of around 50 mm x 50mm. The max print speed is around 10mm/s. Thhe XY motor and Z motor controllers have accuracies of 2um and 0.5um, respectively.
In the next slide, what can see the types of structures that can be printed. In the benchmarking chart, it is demonstrated that they can achieve 2um linewidths with >40% bulk Ag conductivity, which outperforms other reports in the literature. In the right, one can see the types of structures being printed, showing that the printed structure demonstrate high aspect ratios.
Given the highly loaded nature of the pastes as well as the narrow nozzle, fear of constant clogging exists. In the next slide, it is shown that the non-Newtonian pastes can be printed through a 2.5um nozzle for long periods of periods, demonstrating the stability of the process. In the final slide, we showcase the structures which can be printed.
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