Advanced inkjet-based 3D ramp interconnection via dielectric ramp fabrication for multilayered devices

Abstract This study presents an inkjet-based 3D interconnection method that enables compact and reliable electrical connections for vertically stacked or topographically complex devices. To overcome the inherent 2D limitation of inkjet printing, a novel dielectric ramp structure is fabricated exclusively through a surface energy-guided process, allowing precise control over slope geometry. Conductive interconnections are then formed atop the ramp using silver nanoparticle ink, enabling fine-pitch wiring without the need for conventional wire bonding. For proof of concept, the jetting and printing characteristics of the UV-curable dielectric and conductive silver inks were investigated and optimized for high-resolution printing on substrates. Next, surface treatment and dielectric dot patterning techniques were used to locally modulate surface energy, facilitating accurate ramp base formation. The proposed method demonstrates high pattern fidelity and uniformity, with minimum linewidths down to 30 µm, and is further validated using a fully automated printing system tailored for scalable microsystem integration. Beyond stacked chip packaging, this technique is applicable to flexible electronics and 3D MEMS packaging, offering a versatile platform for next-generation electronic device fabrication.