Inkjet-printed gold nanoparticle pillars are investigated as a high-performance alternative to conventional flip-chip interconnects for electronic packages, with significant advantages in terms of mechanical/chemical robustness and conductivity. The process parameters critical to pillar fabrication are described and highly uniform pillar arrays are demonstrated. More generally, this work underscores the impact of sintering on the electrical, mechanical, structural, and compositional properties of three-dimensional nanoparticle-based structures. Using heat treatments as low as 200 degrees C, electrical and mechanical performance that outcompetes conventional lead-tin eutectic solder materials is achieved. With sintering conditions reaching 300 degrees C it is possible to achieve pillars with properties comparable to bulk gold. This work demonstrates the immense potential for both inkjet printing and metal nanoparticles to become a viable and cost-saving alternative to both conventional electronic packaging processes and application-specific integration schemes.