Composition Optimization for High‐Solid‐Loading AlN Tape‐Casting Slurries Toward Highly Thermally Conductive Substrates

ABSTRACT Aluminum nitride (AlN) ceramic substrates are essential for advanced electronics due to their high thermal conductivity and electrical insulation. However, tape‐casting fabrication of dense, high‐thermal‐conductive AlN substrates is often hindered by difficulties in preparing high‐solid‐loading, low‐viscosity, and stable slurries. This study optimized rheological and antisedimentation behaviors by adjusting additive compositions (dispersant, binder, plasticizer) of the tape‐casting AlN slurries. A ternary dispersant system (glycerol trioleate/castor oil/KH560 at a mass ratio of 2:2:2 wt.%) enhanced the rheology and stability of AlN slurry through synergistic chemical anchoring, physical adsorption, and steric hindrance, reducing agglomeration. Optimizing the binder‐to‐plasticizer ratio further improved slurry rheology and stability, as well as enhanced the flexibility, strength, and surface quality of AlN green tapes. Using this approach, slurries with AlN solid loadings of 64–68 wt.% were produced and cast into uniform green tapes, then sintered into dense ceramics. The slurry with 68 wt.% AlN solid loading yielded a substrate with a bulk density of 3.25 g·cm − 3 , apparent porosity of 1.02%, and thermal conductivity of 176.14 W·m − 1 ·K − 1 . These results demonstrate a clear correlation between formulation of AlN slurry and tape‐casting ceramic performance, offering a practical guideline for manufacturing high‐performance ceramic substrates for next‐generation electronics.