Tested.  High levels of >500 Hz and up to 100 g's breaks the self resonating 
legs
Inge

--------------------------------------------------
From: "Thayer, Wayne - IIW" <[log in to unmask]>
Sent: den 12 March 2010 11:18
To: <[log in to unmask]>
Subject: Re: [TN] Vibration issue

> Put a dot of staking adhesive down before you put the part down.
>
> Wayne
>
> -----Original Message-----
> From: TechNet [mailto:[log in to unmask]] On Behalf Of Inge
> Sent: Friday, March 12, 2010 1:48 PM
> 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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