Copper-diamond Composite with Complex Shape by Gelcasting Plus Spark Plasma Sintering

The trend towards miniaturization is leading towards major challenges in the areas of electronic packaging such as cooling and temperature control and is thus leading to new challenges in terms of design and efficiency. To address these challenges, there is growing interest in complex-shaped customized packaging and cooling elements with enhanced thermal conductivity beyond conventional materials. Copper-diamond composites have been reported to possess the highest thermal conductivity up to 700 W/(m*K) @RT in flat geometries. Here we show our efforts to move copper-diamond composites with 60 vol.% diamond into the additive manufacturing space through a combination of gel casting and quasi-isostatic Spark Plasma Sintering (SPS) for complex thermal transfer devices. After green part manufacturing, the structures were subjected to debinding and presintering under hydrogen. A modified Spark Plasma Sintering process was used for densification and adjustment of the thermal conductivity, in which the structures were quasi-isostatically compacted. Sintered samples were measured to have thermal conductivities of 688 W/(m*K) @RT with a density of 5.1 g/cm³. This value is 1.7 times of pure copper (400 W/(m*K) @RT with a density of 8.89 g/cm³). Examples of possible complex shapes and the direct integration of alumina (as electrical isolating layer) will be given. Copper-diamond composites provide access to a new class of 3D cooling structures for direct cooling, which are greatly needed for effective heat dissipation in a wide range of applications, e.g. microelectronics, power modules, charging infrastructure and e-mobility. The developed routine can also be adapted to other high-thermal conductive materials.