Addressing process variation in aerosol jet printing and accelerating conformal electronics manufacturing

Abstract

Aerosol jet printing (AJP) is an additive manufacturing technique used for printing electronics. Capable of printing features on the order of 10-100 μm, AJP excels at patterning on surfaces with 3D topography, such as 3D structures and microelectronics packages, due to its large nozzle-to-surface offset of 1-5 mm. Of particular benefit in R&D applications, AJP is a digital technique capable of printing a wide variety of materials on nearly any substrate, making prototyping convenient. Printed materials often include common conductors, polymeric dielectrics, ceramics, and carbon-based materials, though an ink’s viscosity must be between approximately 1-500 cP. The use of AJP thereby presents a compelling opportunity to manufacture 3D circuits, allowing engineers in aerospace, automotive, medical, and consumer sectors to pursue size or weight reduction explore new types of connected devices. However, AJP has been slow to penetrate into production environments due to problems with process variability and drift. Manufacturing tolerances expected with incumbent electronics fabrication technologies are difficult to hit and quality control tools are lacking. Additionally, while AJP is well-suited for conformal electronics manufacturing, existing hardware and software capabilities are inadequate for AJP to reach its full potential. This work covers recent advances in a process monitoring technique employing light scattering measurements enabling closed-loop operation and data-rich quality control measures. Light scattering measurements have been shown successful over timescales spanning milliseconds to hours, enabling both closed-loop control and in-situ qualification for individual prints. Furthermore, fundamental work related to conformal electronics manufacturing employing an aerosol jet printer mounted on a 6-axis robot arm will support printing on meter-scale structures and multi-layer, conformal circuit manufacturing.