Height Evolution Model Based on Material Properties and Closed-Loop Printing Compensation Method in Inkjet 3D Printing

Inkjet 3D printing has broad application prospects in the field of printed electronics. Surface topography has a significant impact on the electrical performance characteristics of many electronic devices, such as microstrip patch antennas. However, during the printing process, the characteristics of the deposited surface cause changes in the spreading morphology of the droplets. After layer-by-layer stacking, this effect is magnified, causing the surfaces of printed parts to be severely uneven, and ultimately affecting the electrical performance of electronic devices. The present work addresses inkjet 3D printing control and proposes a height evolution model based on material properties. The proposed model involves deriving the spreading diameter of the droplet from the material properties and ejection parameters, based on energy conservation. The quantitative relationship between droplet-spreading contact angle and deposition surface roughness is obtained experimentally, and the shape of the droplet is uniquely determined. In the height evolution model, the shape of the deposited droplet changes dynamically with the number of printed layers. Experimental results show that the height prediction error of the model for printed parts is within 6%, with a corresponding contour prediction error of less than 10 μm. Based on this model, a closed-loop printing compensation method for inkjet 3D printing is proposed. The method involves adding a surface topography measurement device to a traditional printing system and dynamically adjusting subsequent printing layers. The experimental results show that, compared with traditional open-loop printing, the proposed closed-loop printing compensation method reduced printed part surface roughness by 43.26–68.88%, and peak-to-peak profile by 45.40–49.92%. The effectiveness of this method for improving the performance of electronic devices was verified by printing a microstrip patch antenna and measuring the return loss of the printed sample. Compared to samples produced by open-loop printing, those produced by closed-loop printing were more consistent with the simulation design results, and the center frequency deviation was reduced by 80.95%, demonstrating the effectiveness of the proposed method.