Dot-by-Dot Printing of Capacitors by Lift

Abstract

Capacitors play a crucial role in modern electronics as they are widely employed for energy storage, signal processing, radiofrequency tuning and matching, and signal filtering. This paper presents a novel approach to chip-scale capacitor fabrication utilizing the laser-induced forward transfer (LIFT) technique, a versatile 3D printing method that offers a flexible and cost-effective alternative to conventional manufacturing processes. Plate capacitors were fabricated through dot-by-dot printing of titanium di-oxide and silver paste layers, and their performance evaluated. Optimal dot circularity at a diameter of 130 $\mu$m were achieved with printing parameters of 120 mW for 4 ms, with no noticeable surface defects. Using smaller dots enabled higher resolution, but this compromised the quality of the printed surface. The fabricated capacitors demonstrated a mean capacity of 40.1 $\pm$ 2.2 pF at 100 MHz, making them suitable also for high-frequency applications. The resistivity of the printed silver tracks was $1.2\times 10^{-7}\Omega m$, measured over 16 structures, and closely matched the manufacturer's specifications for the silver ink. The achieved resolution from the dot-by-dot method used in this paper provided greater flexibility in transfer in comparison to previously reported results using a square-shaped transfer geometry.