Influence of printing direction and filler orientation on the thermal conductivity of 3D printed heat sinks

Prototype development nowadays can rarely be imagined without 3D printing. In the fast‐moving electronics industry, 3D printing is a good way to react quickly to changing developments, for example, when it comes to heat sinks made of thermally conductive material. 3D printing of thermally conducting plastics, which are also electrically insulating, is an ideal candidate for the rapid generation of heat sink. Nevertheless, 3D printing also shows some drawbacks in regard to properties of the printed parts, as porosities or layer adhesion, emerging from layer deposition in the process. Therefore, the aim of this work was to investigate the influence of the orientation of fillers on the thermal conductivity of filled polylactic acid (PLA). PLA was filled with amounts of 15–45 wt.% of boron nitride and aluminum granules and printed into heat sinks in two different orientations to investigate this influence on the thermal conductivity. The printed heat sinks were then placed on a heated aluminum block and the thermal transport was examined with an infrared camera. It could be shown that especially with platelet‐shaped fillers such as boron nitride, the orientation of these in the test specimen has a large influence on the thermal conductivity. Highlights 3D printing of thermally conductive heat sinks Thermal characterization of 3D printed heat sinks Computer tomography scans of heat sinks to evaluate the porosity Polylactic acid (PLA) filled with thermal conductive fillers were printed in two different directions to investigate the influence of the orientation of fillers on the thermal conductivity. The influence of the printing direction on the thermal conductivity is most significant with platelet shaped fillers.