Re: DSC6000/DSC6000B MEMS oscillator and helium
I couldn't get time on the vacuum chamber, but was able to dump a tank of helium (1500psi) into a chamber with two of these clocks (DSC6011JA3B-016K384) powered on my board. The result is that the frequency did not shift after an hour.
Additionally on the same day, from their tech support archive, Microchip provided the following response to a question from another customer that asked the same question:
"...the DSC6000 MEMS oscillators are sealed to helium gas. No frequency detuning should occur. The pure silicon cavities in which the resonators are housed (produced using our silicon foundry with wafer fusion bonding technology) provide a hard vacuum and do not leak, even with helium."