Odd idea, ol' biker. Will sleep on your proposal. Don't know if that will
stop leads from resonating. The high speed camera may show.
Anyway, must find a very secure way, because you will fly with that box one
day...top engineering solution needed, no place for amateur trials.
/Inge
--------------------------------------------------
From: "John Burke" <[log in to unmask]>
Sent: den 12 March 2010 13:35
To: "'Inge'" <[log in to unmask]>; <[log in to unmask]>
Subject: RE: [TN] Vibration issue
> Actually if you have an open via field behind that QFP and open via holes
> you could under fill it from the back of the board "as is" with a little
> ingenuity - minimal tooling, say a 3/8 inch aluminum "nozzle" on a liquid
> dispenser with a circular recess machined into the end face for a 1/4 inch
> ID O ring machined to half O ring thickness as the depth - contact the
> back
> of the board in the via field behind the QFP, apply light pressure
> referenced to the top of the QFP and apply pressure to the liquid
> dispenser...8-)
>
>
> John Burke
> (408) 515 4992
>
>
> -----Original Message-----
> From: John Burke [mailto:[log in to unmask]]
> Sent: Friday, March 12, 2010 1:23 PM
> To: 'Inge'; [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
>
>
> ______________________________________________________________________
> This email has been scanned by the MessageLabs Email Security System.
> For more information please contact helpdesk at x2960 or [log in to unmask]
> ______________________________________________________________________
>
> ---------------------------------------------------
> Technet Mail List provided as a service by IPC using LISTSERV 15.0 To
> unsubscribe, send a message to [log in to unmask] with following text in the
> BODY (NOT the subject field): SIGNOFF Technet To temporarily halt or
> (re-start) delivery of Technet send e-mail to [log in to unmask]: SET
> Technet
> NOMAIL or (MAIL) To receive ONE mailing per day of all the posts: send
> e-mail to [log in to unmask]: SET Technet Digest Search the archives of
> previous posts at: http://listserv.ipc.org/archives Please visit IPC web
> site http://www.ipc.org/contentpage.asp?Pageid=4.3.16 for additional
> information, or contact Keach Sasamori at [log in to unmask] or 847-615-7100
> ext.2815
> -----------------------------------------------------
>
______________________________________________________________________
This email has been scanned by the MessageLabs Email Security System.
For more information please contact helpdesk at x2960 or [log in to unmask]
______________________________________________________________________
---------------------------------------------------
Technet Mail List provided as a service by IPC using LISTSERV 15.0
To unsubscribe, send a message to [log in to unmask] with following text in
the BODY (NOT the subject field): SIGNOFF Technet
To temporarily halt or (re-start) delivery of Technet send e-mail to [log in to unmask]: SET Technet NOMAIL or (MAIL)
To receive ONE mailing per day of all the posts: send e-mail to [log in to unmask]: SET Technet Digest
Search the archives of previous posts at: http://listserv.ipc.org/archives
Please visit IPC web site http://www.ipc.org/contentpage.asp?Pageid=4.3.16 for additional information, or contact Keach Sasamori at [log in to unmask] or 847-615-7100 ext.2815
-----------------------------------------------------
|
