Ultrasonic treatment of aerosol jet printed traces

Aerosol jet printing (AJP) is a contactless direct-write approach aimed at the production of fine features on a wide range of substrates. The technology has been explored for a variety of applications, including active and passive electronic components, actuators, sensors, and a variety of selective chemical and biological responses. However, the quality of conductive traces printed with nanoparticle inks using AJP can be affected by several factors, including carrier and sheath gas flow rate, ink properties, and substrate material properties. A typical defect present in the prints, such as non-uniform metal particle distribution, solvent local concentration, porosity, delamination, and bubbles, can be reduced by additional ultrasonic post-printing treatment. Therefore, the article investigates the influence of the self-designed sonotrode tool on the quality of conductive traces printed with nanoparticle inks using AJP. An ultrasonic head was fixed in a tandem position behind a printing nozzle at a distance equal to the node of ultrasonic waves. In this article, it was found that ultrasound has a positive effect on the quality of printed traces by improving degassing with simultaneous uniform particle distribution. As a result, the surface open porosity obtained for printed and ultrasonically treated traces was decreased almost seven times from 17.2 to 2.7%, respectively. An improved surface and structural morphology increased electrical resistivity in the prints from 6.85 to 4.57 µΩ cm. The analysis included quantifying the macroscale geometry, electrical properties, and micromorphological characteristics of the traces. The results of this article suggest that the application of ultrasonic-assisted aerosol jet printing with a proper tool improves the quality of AJP prints.