How sensitive to atmospheric environment are MEMs oscillators ? https://www.reddit.com/r/sysadmin/comments/9si6r9/postmortem_mri_disables_every_ios_device_in/ It gets closer to time-nuts territory in the earlier discussion - see captaincool's contribution some way down : https://www.reddit.com/r/sysadmin/comments/9mk2o7/mri_disabled_every_ios_device_in_facility/

On 10/30/18 3:50 AM, Adrian Godwin wrote: > How sensitive to atmospheric environment are MEMs oscillators ? > > https://www.reddit.com/r/sysadmin/comments/9si6r9/postmortem_mri_disables_every_ios_device_in/ > > > It gets closer to time-nuts territory in the earlier discussion - see > captaincool's contribution some way down : > > https://www.reddit.com/r/sysadmin/comments/9mk2o7/mri_disabled_every_ios_device_in_facility/ > The helium leak sounds a bit sketchy, especially when you're talking about a system that has large RF and magnetic fields. Why would a MEMS resonator care about what gas it is surrounded by. That said, I recall someone telling me about problems with early MEMS RF switches and needing some trace amount of water vapor to make them work - work fine on the bench, but them into thermal vacuum testing and after some amount of time they stop working, as the H2O diffuses out of the (non-hermetic) packages.

Hi More than sketchy, it sounds a bit crazy. MEMS are not a lot different than any IC in that you can get packaging issues. Put them in a high pressure “bomb” test and you will see the same issues that you do on any IC. The gotcha is that an IC is die coated and a MEMS oscillator likely is not. They should get packaged accordingly (= a low leakage package). Getting anything into a package at normal atmospheric pressure … not so much. Bob > On Oct 30, 2018, at 8:44 AM, jimlux <jimlux@earthlink.net> wrote: > > On 10/30/18 3:50 AM, Adrian Godwin wrote: >> How sensitive to atmospheric environment are MEMs oscillators ? >> https://www.reddit.com/r/sysadmin/comments/9si6r9/postmortem_mri_disables_every_ios_device_in/ >> It gets closer to time-nuts territory in the earlier discussion - see >> captaincool's contribution some way down : >> https://www.reddit.com/r/sysadmin/comments/9mk2o7/mri_disabled_every_ios_device_in_facility/ > > The helium leak sounds a bit sketchy, especially when you're talking about a system that has large RF and magnetic fields. Why would a MEMS resonator care about what gas it is surrounded by. > > That said, I recall someone telling me about problems with early MEMS RF switches and needing some trace amount of water vapor to make them work - work fine on the bench, but them into thermal vacuum testing and after some amount of time they stop working, as the H2O diffuses out of the (non-hermetic) packages. > > > > _______________________________________________ > time-nuts mailing list -- time-nuts@lists.febo.com > To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com > and follow the instructions there.

Helium is lower density, a feature used to reduce turbulence in patients with airway stenosis. Perhaps the lower density changes the resonant frequency of the MEMS oscillators. (Though the penetration and concentration are rather suspect in this description.) Paul Alfille On Tue, Oct 30, 2018 at 9:55 AM Bob kb8tq <kb8tq@n1k.org> wrote: > Hi > > More than sketchy, it sounds a bit crazy. > > MEMS are not a lot different than any IC in that you can get packaging > issues. Put them > in a high pressure “bomb” test and you will see the same issues that you > do on any IC. > The gotcha is that an IC is die coated and a MEMS oscillator likely is > not. They should > get packaged accordingly (= a low leakage package). > > Getting anything into a package at normal atmospheric pressure … not so > much. > > Bob > > > On Oct 30, 2018, at 8:44 AM, jimlux <jimlux@earthlink.net> wrote: > > > > On 10/30/18 3:50 AM, Adrian Godwin wrote: > >> How sensitive to atmospheric environment are MEMs oscillators ? > >> > https://www.reddit.com/r/sysadmin/comments/9si6r9/postmortem_mri_disables_every_ios_device_in/ > >> It gets closer to time-nuts territory in the earlier discussion - see > >> captaincool's contribution some way down : > >> > https://www.reddit.com/r/sysadmin/comments/9mk2o7/mri_disabled_every_ios_device_in_facility/ > > > > The helium leak sounds a bit sketchy, especially when you're talking > about a system that has large RF and magnetic fields. Why would a MEMS > resonator care about what gas it is surrounded by. > > > > That said, I recall someone telling me about problems with early MEMS RF > switches and needing some trace amount of water vapor to make them work - > work fine on the bench, but them into thermal vacuum testing and after some > amount of time they stop working, as the H2O diffuses out of the > (non-hermetic) packages. > > > > > > > > _______________________________________________ > > time-nuts mailing list -- time-nuts@lists.febo.com > > To unsubscribe, go to > http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com > > and follow the instructions there. > > > _______________________________________________ > time-nuts mailing list -- time-nuts@lists.febo.com > To unsubscribe, go to > http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com > and follow the instructions there. >