In-Situ Image-Based Monitoring and Closed-Loop Control of Aerosol Jet Printing

Aerosol jet printing (AJP) is a complex process for additive electronics that is often unstable. To overcome this instability, real-time observation and control of the printing process using image based monitoring is demonstrated. This monitoring is validated against images taken after the print and shown highly correlated and useful for determination of printed linewidth. These images and the observed linewidth are used as input for closed-loop control of the printing process, with print speed changed in response to changes in observed linewidth. Linear regression is used to relate these quantities and forms the basis of a proportional control. A test using multiple print speeds and the observed linewidths is used to set the control gain. Electrical test structures were printed with controlled and uncontrolled printing, and it was found that the control influenced their linewidth and electrical properties, giving improved uniformity in both size and electrical performance.