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Date: | Fri, 12 Mar 2010 14:01:02 -0800 |
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Why a standoff?
Inge
--------------------------------------------------
From: "John Burke" <[log in to unmask]>
Sent: den 12 March 2010 13:22
To: "'Inge'" <[log in to unmask]>; <[log in to unmask]>
Subject: RE: [TN] Vibration issue
> Inge, the mass of the package is probably not helping here. Have you tried
> an approach such as using a low height standoff on the part and then
> effectively under filling the assembly?
>
>
> John Burke
> (408) 515 4992
>
>
> -----Original Message-----
> From: TechNet [mailto:[log in to unmask]] On Behalf Of Inge
> Sent: Friday, March 12, 2010 10:48 AM
> To: [log in to unmask]
> Subject: [TN] Vibration issue
>
> Hi all,
> we are making a very vital part for a aircraft builder. Problem with
> TQFPs,
> some 200 legs. There are resonance peaks that kill the package legs.
> Redesign is not to think of from the customer, so we must do something on
> inside of the box. One solution (not popular) is to use a string of a
> glue
> along the leg rows in order to lock them. Another is to place a vibration
> dampening mat on one side of the board. That one is more tricky , but
> there
> is a US company with lots of stuff for that purpose. Anyone with
> experience from this area? I should add that not all legs are broken, just
> one or two after 100 hs of random vibration, but that is of course not
> acceptable. BGAs would solve the problem, but there is no time for
> redesign.
> I'm sorry for coming with a serious message at this holy time of the
> week.
> Thanks
> /Inge
>
>
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