Accurate at-line measurement of deposition rate for aerosol jet printing for the fabrication of 3D patterns and resistors with high precision

Aerosol jet (AJ) printing has gained significant attention in printed electronics for its high resolution and non-contact capabilities. However, batch-to-batch variations in printed products due to the difficulty of precisely controlling the amount of ink deposited have prevented its widespread use in production. A major challenge is to achieve direct, precise, and ink-unrestricted at-line measurement of the deposition rate (DR). By incorporating a photoetched inkwell and a mechanical shutter system with a high-pressure air-blowing device, a direct and precise at-line DR measurement during the printing process is established. A pneumatic shutter is used to briefly interrupt the printing process and enable multiple at-line measurements during printing. Utilizing this approach, three printable inks, including polyurethane acrylate, silver nanoparticles, and conductive carbon black, were employed to fabricate three-dimensional (3D) patterns with predetermined geometries or resistors with specific target resistances. Precise at-line DR control enabled the crafting of polymer structures with height deviations of just 3.48 % from the design specifications. Each group of 18 resistors, with target values of 1 Ω, 10 Ω, 1 kΩ, and 10 kΩ without postprocessing, achieved average errors of 2.49 %, 2.32 %, 2.94 %, and 2.34 %, respectively. This methodology offers a crucial tool for addressing precise fabrication challenges, as demonstrated here for both 3D patterns and passive components of conformal electronics using AJ printing.