PCB thickness for 3U backplane

[radar_macgyver]

I have a design that needs a custom backplane for 3U Eurocards. Could I get away with the standard 1.6mm PCB thickness, or would I need to use a thicker and more expensive PCB? This would be purely for mechanical strength, not for signal routing. Connectors used would be DIN 41612, with coax pins. The backplane would fit inside a card cage, like a Schroff Europac:

https://schroff.nvent.com/wcsstore/ExtendedSitesCatalogAssetStore/Attachment/SchroffAttachments/Documents/6_1_europacPRO_e_.pdf

Thanks in advance.

[Benta]

1.6 mm is enough, that's what other backplanes are.

[Siwastaja]

Should be designed so that the connector plastic directs the insertion force into the case, so no PCB flexing occurs.

[radar_macgyver]

Thanks for the replies!

1.6 mm is enough, that's what other backplanes are.

Some examples I found of commercial 3U backplanes indicated 4 mm thick backplanes, as did an old 6U VME backplane I dusted off at work. I suppose it could have been over-designed, or that VME requires higher layer count.

Should be designed so that the connector plastic directs the insertion force into the case, so no PCB flexing occurs.

The enclosure drawings show the mounting holes to be 128.55 mm apart. The DIN 41612 connector mounting holes are 90 mm apart, leaving 15 mm of PCB on each side to take up the insertion force. Maybe I need to add a stiffener? The enclosure catalog shows a direct mount, see attached.

[cat87]

From what i've seem the 16mm backplane is quite stiff if you use the lower and upper bolt holes and shouldn't flex when inserting or removing a card.  I have a few at home and none use a stiffener.

Update 5.07.2018:
    I just tried attaching a bacplane to two z rails on a 3u 19 inch subrack to see how stiff everythong is. I bolted the backplane using both the holes for thw DIN connectors and the row of holes above those. I have to say it's rock solid.
   
    Can't really get to bendt it much even when applying more force than needed for card insertion.