Co-Printed and Co-Sintered Packaging for Thermal Transfer Devices with LTCC and Copper

The demand for advanced materials in additive manufacturing has expanded from basic steels to more sophisticated composites and ceramics, enabling the production of high-performance materials and combinations. A significant challenge in device manufacturing is managing thermal flux and mitigating thermal expansion mismatches. By leveraging additive manufacturing and combining advanced materials, custom thermal transfer devices and packages made from alumina ceramics and copper can provide better thermal flux management and reduce thermal mismatches, ultimately increasing device lifetimes. In this work, we report on the continued development and optimization of processing and sintering conditions for a feedstock that combines low-temperature co-fired alumina ceramic (LTCC) with copper and copper-diamond composites. We explore the use of LTCC and copper in a fused filament fabrication (FFF) process for co-sintering. Specifically, we investigated how inorganic additives affected the sintering temperature of LTCC, enabling sintering at a copper-compatible temperature. We also examined the impact of polymer composition and material loading on feedstock extrusion, 3D patterning, and solvent debinding. We evaluated the mechanical properties of 3D-printed parts and studied the influence of inert vacuum versus air atmospheres on the final product, and its impact on densification. To characterize our results, we employed thermogravimetric analysis, 3D scanning, scanning electron microscopy, cross-sectional analysis, x-ray diffraction, tensile testing and thermal transfer. Through process optimization in printing, debinding, and sintering, we achieved >95% of the theoretical density for LTCC, with sintering temperatures between 1000-1100°C without post-processing. This research broadens the material selection available for FFF and opens new possibilities for using LTCC and copper-based 3D-printed components in advanced technological applications.