Chen, Yi-Dan, Nagarajan, Vijayasarathi, Rosen, David W., Yu, Wenwei, Huang, Shao Ying, Aerosol jet printing on paper substrate with conductive silver nano material, Journal of Manufacturing Processes Volume 58, October 2020, Pages 55-66, https://doi.org/10.1016/j.jmapro.2020.07.064
The SEM images of the top view and cross-sectional view of the printed structures when different numbers of layers are finished (i.e., printed and sintered) in the proposed optimized sintering sequence.
Aerosol jet printing (AJP) is a promising method for micro-scaled digital additive manufacturing for printed electronics. It usually requires a high sintering temperature (280 °C) and a long sintering time (e.g., 12 h on a glass substrate) to guarantee a high conductivity of the printed structures, which has limited AJP to only a few types of substrates. Moreover, the printed metallic structure peels off from the substrate easily. In this paper, a procedure of AJP printing on cellulose fiber paper is proposed, which includes the use of cellulose fiber paper as the substrate, and a new sintering method, i.e., hot-air sintering with an optimized sequence. With the proposed approach, the sintering temperature is significantly lowered (80 °C), and the sintering time is considerably shortened (40 min). The printed structure has a measured sheet resistance of 1.13 × 10−2 Ω/m2 which is equivalent to a conductivity of greater than 106 S/m and close to that of the bulk silver (6.30 × 107 S/m), and it has good adhesion to the substrate. The determinant factors underlying the diffusion and curing processes of AJP, i.e., the properties of the substrate (cellulose fiber paper), the printing parameters, the sintering parameters, and the sequence were systematically investigated. The investigation is carried out through evaluation of the morphologies of the printed structures based on scanning electron microscope (SEM) images and through the study of the correlation between the morphology and the conductivity of the structures. Moreover, the proposed paper-based AJP electronics offer tremendous flexibility. They can be folded, bent, and pasted to any surface. This proposed cellulose-fiber-paper-based AJP opens a window for low-cost, eco-friendly, flexible, and high-resolution printed electronics. It will be an essential alternative fabrication approach for flexible electronic circuits, antennas, and electromagnetic-functioning surfaces, such as reconfigurable meta-surfaces.