On the application of components manufactured with stereolithographic 3D printing in high vacuum systems

Abstract

We explore the ultrahigh-vacuum (UHV) compatibility of Formlabs ‘Clear Resin’ via vat photopolymerisation (VPP). We report on a method for using VPP additive manufacturing, specifically Formlabs’ widely available stereolithographic (SLA) printing using their ‘Clear Resin’ material, to rapidly and cheaply prototype components for use in high-vacuum (HV) environments. We present pump down curves and residual gas analysis to demonstrate the primary vacuum contaminant from freshly printed SLA plastics is water with no evidence of polymers outgassing from the material and thus the vacuum performance can be controlled with simple treatments which do not involve surface sealing. An unbaked vacuum system containing SLA printed components achieved 1.9 $\times$ 10^-8 mbar base pressure whilst retaining structural integrity and manufacturing accuracy. Outgassing rates in the HV test chamber and preliminary results in a UHV chamber indicate that our method can be extended to achieve ultrahigh-vacuum compatibility. We further report on the effect of atmospheric exposure to components and present evidence to suggest that water re-ad/absorption occurs exclusively on the surface, by showing that the bulk mass changes of the material is irreversible on the timescale investigated ($<2$weeks).