[time-nuts] Re: hydrogen rich environment and oscillators

[Lux, Jim]

On 12/13/22 5:57 AM, Bob Camp wrote:
> Hi
>
> If you have a welded package TCXO, it’s a reasonable guess that it may have gone
> through the normal “mil spec” leak test. Mil STD-202 method 112 test condition C
> gives you all sorts of fun information. It also heads off in many directions.
>
> As normally done on a crystal oscillator, you put the parts in a pressure vessel for
> about an hour. It’s pressurized at around 50 PSI with 10% helium. Yes both the time
> and pressure are past what method 112 calls out as the minimums.
>
> After being soaked like this, they go into a mass spectrometer to look for helium
> coming back out of the parts.
>
> Pretty much any mil spec or space spec welded part would go through that test or
> something very much like it. That’s true regardless of who made the part.
>
> The only relevant point here is that if this sort of exposure killed the parts, it would
> show up and folks would very much know about it.
>
> Welded crystals going into precision oscillators get the same sort of leak check or
> possibly something more in depth. There’s no guarantee on this so it’s not quite as
> much a sure thing as the space or mil oscillators. Still, if this killed crystals you would
> know about it.
>
> Before anybody asks, yes, some parts do leak. I don’t remember any of them being
> non-functional. However, you don’t test those parts much. They are headed to the
> recycle bin.
>
> Bob


OK. so welded packages (particularly those that are procured for space) 
aren't likely to leak, they tested, etc. I'm sort of interested, though 
in COTS cheap oscillators like these tiny $1 Abracon units.  (I don't 
know what they use on Arduinos and RPi, but it's something like this).

https://www.mouser.com/datasheet/2/3/ASEseries-38758.pdf

They're sort of silent on the datasheet about sealing, etc.  And at 
$1.38 each, do they actually leak test them?