Void-less metallization of high aspect ratio through glass via using electrohydrodynamic drop-on-demand printing

This paper presents a novel method for metallizing high-aspect-ratio through glass vias (TGVs) using a drop-on-demand electrohydrodynamic (DoD EHD) printing technique. Through parameter optimization, including the evaporation time, filling time, voltage amplitude, and curing temperature, the technique achieved void less deposition of Ag nanoparticles within the TGVs. Exploring the temperature effects on filling revealed challenges such as void formation and nozzle clogging. The voltage amplitude significantly affected the filling time, balancing between reduced time and potential drawbacks. Additionally, the study examined the electrical properties and found that higher curing temperatures improved the conductivity. By optimizing these parameters, complete Ag deposition was achieved even in TGVs with aspect ratios as high as 16.3, thereby eliminating voids. Optimized curing temperatures yielded a resistance as low as 20 mΩ for an aspect ratio of 6.25. In summary, the proposed DoD EHD printing method offers a promising solution for metallizing high-aspect-ratio TGVs, with applications in 3D electronics.