A new method to hermetically seal FDM prints applied to pressure vessels and clean room-grade wafer holders

This paper presents a new method to print hermetically sealed fused deposition modeling (HS-FDM) test articles in air, at ambient pressures, using conventional FDM printers, and without any cumbersome post-processing techniques. While FDM prints are notoriously porous, HS-FDM test articles withstand at least 3,000 psi, a limit set in this work only by safety concerns during testing. A side-by-side comparison of FDM and HS-FDM test articles with identical geometries reveals a 200-fold improvement in the high-pressure air leak rate time constant. It is the first time that 3D-printed pressure vessels sustain such high pressures. The pressurized volume is 7mL; the hermetic sealing method scales to larger volumes. Because the stress level that compromises the vessel's structural integrity is unknown, we did not attempt to pressurize larger test articles. Instead, we verified their hermiticity by immersing the larger prints in common acids and solvents.