5 ms·

How does it fare in a slightly-helium-rich environment? That story about every iPhone in a hospital shutting down for a week after an MRI shutdown turned out to

by ohazi 8y ago

How does it fare in a slightly-helium-rich environment? That story about every iPhone in a hospital shutting down for a week after an MRI shutdown turned out to be due to not-quite-hermetically sealed packaging of the silicon mems resonators.

baybal2 8y ago
Ceramic piezo oscillators and silicon mems oscillators are a very different technology based on different physics. What matters here is the speed of sound in that ceramic piezo material. Can helium change that by much? I don't know.
- ohazi 8y ago
  ...Yes? That's why I asked.
- vanderZwan 8y ago
  Technically, you are not answering GP's question.
pkaye 8y ago
From this old paper, I think quartz crystal oscillators are still vulnerable. It all depends on the packaging. https://tf.nist.gov/general/pdf/906.pdf https://tf.nist.gov/general/pdf/906.pdf
tzs 8y ago
Based on the video here [1] and some of the links on that page, plus assorted diagrams of other bulk acoustic wave resonators, I don't think there will be any problem. Helium can interfere with devices that either depend having a vacuum in a volume or depend on having that volume contain a gas mixture with specific properties. Helium getting in messes that up. The BAW on-die-oscillators do not appear to have any places that are supposed to be vacuum or supposed to contain gas. The have two piezoelectric thin films, with acoustic reflectors behind them. The gap between them appears to be solidly filled. All the relevant acoustic waves are carried in that solid stuff, not in air. (This also means, I think, that these things should be OK in vacuum). [1] https://training.ti.com/tis-bulk-acoustic-wave-clocking-technology-0 https://training.ti.com/tis-bulk-acoustic-wave-clocking-tech...
- SamReidHughes 8y ago
  The helium problem was because of helium working its way into the crystal structure of the resonator and affecting its springiness.

by ohazi 8y ago

baybal2 8y ago

Ceramic piezo oscillators and silicon mems oscillators are a very different technology based on different physics. What matters here is the speed of sound in that ceramic piezo material. Can helium change that by much? I don't know.

ohazi 8y ago
...Yes? That's why I asked.
vanderZwan 8y ago
Technically, you are not answering GP's question.

pkaye 8y ago

From this old paper, I think quartz crystal oscillators are still vulnerable. It all depends on the packaging. https://tf.nist.gov/general/pdf/906.pdf https://tf.nist.gov/general/pdf/906.pdf

tzs 8y ago

Based on the video here [1] and some of the links on that page, plus assorted diagrams of other bulk acoustic wave resonators, I don't think there will be any problem. Helium can interfere with devices that either depend having a vacuum in a volume or depend on having that volume contain a gas mixture with specific properties. Helium getting in messes that up. The BAW on-die-oscillators do not appear to have any places that are supposed to be vacuum or supposed to contain gas. The have two piezoelectric thin films, with acoustic reflectors behind them. The gap between them appears to be solidly filled. All the relevant acoustic waves are carried in that solid stuff, not in air. (This also means, I think, that these things should be OK in vacuum). [1] https://training.ti.com/tis-bulk-acoustic-wave-clocking-technology-0 https://training.ti.com/tis-bulk-acoustic-wave-clocking-tech...

SamReidHughes 8y ago
The helium problem was because of helium working its way into the crystal structure of the resonator and affecting its springiness.