Hello Michael-

Based on the info provided in your question, the best responses I can come
up with are:

-Most everything is driven by cost and feasibility. If the job can be done
cheaper with interconnected rigid boards, that's probably the way it will
go.

-You should not 'flex' a rigid board, except.... I've heard of rigid boards
being routed part way through and then bent, with heavy traces
perpendicular to the fold (and on the opposite side of the cut, of course).
No personal experience, but it's used in a German automotive application.
Maybe just prototypes so far. If it goes to production, you'd have some
pretty good reliability data behind the concept.

Best Regards,
-Chris






                       "Simms, Michael"
                       <[log in to unmask]>            To:   [log in to unmask]
                       Sent by: TechNet                  cc:
                       <[log in to unmask]>                 Subject:    [TN] FW: Flexible vs. rigid
                                                           substrates
                       01/10/2005 05:50 PM
                       Please respond to TechNet
                       E-Mail Forum; Please
                       respond to "Simms,
                       Michael"







Hello T'Netters,
In the absence of any replies to a question that  I believe  many of you
should have knowledge about, please allow me to re-post:

> Recently, the issue of the use of rigid printed wiring boards in an
> application
> which demands that printed wiring boards be pressed into an outer shell
> with some
curvature has surfaced.
> I'm accustomed to the use of flexible substrates for any  applications
> which demand
that the board does not stay flat.
> However, I don't see any IPC document which mandates the use of rigid
> boards
> for 180-degree assembly applications and flex boards (or rigid-flex) for
> anything else.
>
Should rigid boards be used in applications which demancd that
the assemblies be flexed to some degree?
> Are there any guidelines for the selection of one type over another?
> Are there any reliability issues with the use of surface mount devices on
> flex boards which don't also apply to rigid boards?
> Why would a manufacturer opt for a rigid board over a flex board for
> assemblies which
> are subsequently flexed?  Is this a choice based on cost?
Thanks,
Regards,
Mike

Mike Simms
Chemist
Trace Laboratories - Central
1150 W. Euclid Ave.
Palatine, IL  60067

phone  847-934-5300
fax      847-934-4600
www.tracelabs.com

Notice:  This message is confidential and intended for the private use of
the addressee only.

>

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