Thermoformable Boron Nitride Based All‐Ceramics

Abstract Thermoforming processing, traditionally reserved for thermoplastic polymers and sheet metals, is extended here to boron‐based all‐ceramics. Specifically, sintered boron nitride composite sheets manufactured via a combined vibration and tape‐casting photopolymerization process exhibit a highly oriented microstructure that allows these preform sheets to flow as viscous Bingham pseudoplastics during compression molding. These sintered all‐ceramic preforms are thermoformed into thin, complex parts with features down to 200 µm. Further, a new workflow is leveraged to generate bespoke all‐ceramic heat spreaders that can be press‐fit onto printed circuit boards and outperform metal heat sinks as a low‐profile thermal management solution. This work offers a route for other all‐ceramics that may be thermoformed through first fabricating pre‐forms with highly‐ordered anisotropic microstructures.