**
*IPC-6012 3.4.4 Bow and Twist*
Unless otherwise specified in procurement documentation
when designed in accordance with IPC-2221 5.2.4
maximum bow and twist .75% for boards that use SMT,
1.5% for other

if you need to automate, here's my only lead...
http://www.warpfinder.com/

seeya at PCBWest?
Jack



On 3/8/07, McGlaughlin, Jeffrey A <[log in to unmask]> wrote:
>
> Technet and DesignersCouncil Gurus -
>
> I have been asked by our mechanical engineering group to find out if
> there is a standard or specification for post assembly flatness of
> printed circuit cards.  This has never been an issue for functional
> failure but a new design requires that a row of LEDs mate to a display
> panel mask such that no light leaks from one LED cell to the next. Their
> concern is that post assembly bow and twist will over stress solder
> joints and board copper if they mechanically stress the cards by
> pressing/pulling them flat to an assembly frame.  Can anyone direct me
> to a standard or advise me on the maximum allowable bow and twist for
> this type of situation?
>
>
> Jeffrey McGlaughlin, CID
> Engineering Designer
> Battelle
> 505 King Avenue
> Columbus Ohio 43201-2693
> (614)424-7582 Phone
> (614)458-7582 Fax
>
>
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>
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