Und da du die Originalquelle ja immer noch nicht gelesen zu haben scheinst:
How effective is the hermetic seal of MEMS oscillators??
SiTime’s EpiSeal resonator is impervious to the highest concentration elements in the atmosphere, nitrogen and oxygen, and therefore acts as a perfect seal. Previous generations of EpiSeal resonators may have been impacted by large concentrations of small-molecule gas. Newer EpiSeal resonators are impervious to all small-molecule gases. Please contact SiTime in case you are planning to use a SiTime device in large concentrations of small-molecule gas, so that we can recommend an appropriate, immune part.
Small-molecule gas = Helium. Previous generations = was Apple verbaut hat.