Hybrid additive manufacturing of low-temperature consolidation substrates based on sodium silicate solution polycondensation

Hybrid additive manufacturing technology, integrating Direct Ink Writing (DIW) and Material Jetting (MJ), offers a robust solution for fabricating three-dimensional ceramic electronics. However, in the traditional high-temperature co-firing process, there is a significant difference in thermal shrinkage rates between the wiring and the substrate. This study proposes an all-inorganic Na2SiO3-SiO2 composite system capable of low-temperature consolidation (∼300°C) driven by the hydrolysis-condensation reaction of the silicate binder. To ensure densification, the printed structures are immersed in isothermal mineral oil to promote dehydration and reduce defects through uniform hydrostatic pressure. Quantitative characterisation reveals that the differential shrinkage between the ceramic substrate and silver conductor is minimised to 0.23%, effectively mitigating interfacial delamination. The obtained substrates exhibit low dielectric properties with a dielectric constant of 3.76 and a dielectric loss of 0.0013 at a test frequency of 10 GHz, while the printed silver lines achieve a high electrical conductivity of 5.1 × 105 S/cm. Notably, the all-inorganic system demonstrates exceptional thermal tolerance, withstanding thermal shocks up to 500°C without interfacial delamination. The feasibility of this methodology is validated by an X-band microstrip patch antenna, which demonstrates a resonant frequency of 10.02 GHz and a radiation efficiency of 88.49%.