[AR] Re: Flight Computer
- From: Uwe Klein <uwe@xxxxxxxxxxxxxxxxxxx>
- To: arocket@xxxxxxxxxxxxx
- Date: Tue, 22 Dec 2015 09:55:48 +0100
Am 22.12.2015 um 05:11 schrieb Jonathan Goff:
Ben,
Random vibe is probably something matters more when you're dealing with
larger rockets and more aggressive mass ratios. It's also a good way to
check for workmanship quality.
Resonance is/kills everything.
First iteration of the MIRO preprocessor board we lost the Actel FPGAs (
196pin ceramic flatpack afair ) to fatique in the leads. They broke of
at the package interface. ( glued on copper wick for heat transfer
to the enclosure was the culprit. too much mass )
This is not readily visible and lead to random "microphonic" errors.
You can hear the faults if you lightly strike along the leads with a
needle. this also exposes soldering issues.
the intact ones give a "pling" while the other ones make a "scratch"
sound.
As a method it is not limited to items with long leads works on SO and
PLCC packages as well.
This also exposes some invisible soldering issues.
uwe
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