3D-Printed Hermetic Alumina Housings

Ceramics are repeatedly investigated as packaging materials because of their gas tightness,
e.g., as hermetic implantable housing. Recent advances also make it possible to print the established
aluminum oxide in a Fused Filament Fabrication process, creating new possibilities for manufacturing
personalized devices with complex shapes. This study was able to achieve integration of channels
with a diameter of 500 m (pre-sintered) with a nozzle size of 250 m (layer thickness 100 m) and
even closed hemispheres were printed without support structures. During sintering, the weightbearing
feedstock shrinks by 16.7%, resulting in a relative material density of 96.6%. The well-known
challenges of the technology such as surface roughness (Ra = 15–20 m) and integrated cavities
remain. However, it could be shown that the hollow structures in bulk do not represent a mechanical
weak point and that the material can be gas-tight (<10􀀀12 mbar s􀀀1). For verification, a volume-free
helium leak test device was developed and validated. Finally, platinum coatings with high adhesion
examined the functionalization of the ceramic. All the prerequisites for hermetic housings with
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integrated metal structures are given, with a new level of complexity of ceramic shapes available.