Universal Liquid Metal Interconnects for Next-Generation Glass Packaging

Abstract

Advances in 2.5D heterogeneous integration demand interconnect technologies that combine fine pitch, thermal and mechanical reliability, and scalable manufacturability on glass interposers. Here, we introduce a versatile platform that exploits the fluidic and electrical properties of gallium-based liquid metal (LM), leveraging LM's larger skin depth than copper to mitigate high-frequency skin-effect losses. First, vacuum-assisted capillary infiltration forms conformal, void-free LM-filled through-glass vias, eliminating seed-layer deposition and electroplating while lowering thermal budget. Second, 3D direct microprinting of LM writes interconnects with 5 & micro;m resolution, enabling dense chip-to-interposer fan-out beyond wire-bonding limits. Third, an LM-based anisotropic conductive adhesive (LM-ACA) provides vertical electrical interconnection and mechanical adhesion at room temperature and low pressure, reducing assembly complexity and supporting panel-scale integration. Integrating these technologies, we demonstrate stable operation, including real-time sensing, processor operation, and chip-to-chip communication, establishing LM as a fine-pitch, thermally resilient, and scalable interconnect medium for glass-based 2.5D packaging.