There is an old rule of thumb regarding the mechanical support
needed for printed circuit boards/assemblies.  For polymer
based materials (epoxies) the minimum spacing between
mounting posts, bosses, connecting tabs, etc. is calculated as
the board thickness multiplied by 50.

Example, for a .062" thick board....062" x 50 = 3.1".
That is, there should be some form of mechancial
support every 3.1" minimum.  If you are panelizing for assembly,
the same rule applies for the connecting tabs (webs).

Typical examples:       Board                     Minumum  Mechanical
                               Thickness   x50  =         Support Spacing
                                  .020"                                 1.00"

                                  .031"                                 1.55"
                                  .062"                                 3.10"
                                  .093"                                 4.65
                                  .125"                                 6.25

This is an excellent subject to discuss at this time.  For years we
have been spoiled rotten by the excellent mechanical characteristics
of the .062" conventional  boards.  Now with the thinner boards, we are
experiencing a whole new set of failure modes with surface mount parts
and the thinner  boards.  Surface mount often precludes the use of
stiffeners because of the need to stencil the solderpaste.  As a result,
solder joint fatigue and component cracking are far too common.

Hope this helps.

Mary Sugden
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