Hi
A mil standard leak test works like this:
First you run a bubble leak, generally in something like hot synthetic oil. If the leak
is too big, you will not catch it with a helium test.
Next you put the parts in a pressure vessel and pressurize it with helium (or possibly
a gas mix). How high a pressure and how long depend a bit on just what you are testing.
After they have soaked for a while, you de-pressurize and let the residual gas on the
surface of the parts fly away. That does not take long at all.
The go into a mass spectrometer and get pumped down while it looks for an outflow
of helium. A flow above a certain level means it’s a failure. What that level is depends
on the spec on the part and it’s size.
Many thousands of parts get tested this way every (working) day of the year.
Bob
Helium leak testing is a very common thing in the oscillator industry. I’d
bet it also is done in the MEMS oscillator business as well.
How does that test work?
It seems obvious how to test stuff that is designed to hold Helium - put the
Helium in and sniff the surrounding air to see if any leaks out. But how do I
test a small package to see if any leaks in?
Maybe give it a chance to leak in for a while and then see if any leaks out?
--
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Hi
A mil standard leak test works like this:
First you run a bubble leak, generally in something like hot synthetic oil. If the leak
is too big, you will not catch it with a helium test.
Next you put the parts in a pressure vessel and pressurize it with helium (or possibly
a gas mix). How high a pressure and how long depend a bit on just what you are testing.
After they have soaked for a while, you de-pressurize and let the residual gas on the
surface of the parts fly away. That does not take long at all.
The go into a mass spectrometer and get pumped down while it looks for an outflow
of helium. A flow above a certain level means it’s a failure. What that level is depends
on the spec on the part and it’s size.
Many thousands of parts get tested this way every (working) day of the year.
Bob
> On Nov 1, 2018, at 2:40 PM, Hal Murray <hmurray@megapathdsl.net> wrote:
>
>
> kb8tq@n1k.org said:
>> Helium leak testing is a *very* common thing in the oscillator industry. I’d
>> bet it also is done in the MEMS oscillator business as well.
>
> How does that test work?
>
> It seems obvious how to test stuff that is designed to hold Helium - put the
> Helium in and sniff the surrounding air to see if any leaks out. But how do I
> test a small package to see if any leaks in?
>
> Maybe give it a chance to leak in for a while and then see if any leaks out?
>
>
> --
> These are my opinions. I hate spam.
>
>
>
>
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