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Apalis Carrier Board Design Guide
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4.2 Fixation of the Module
The MXM3 connector itself does not features a locking mechanism. The mobile graphic cards using
the MXM3 connector are all screwed down to the carrier board for fixation. The Apalis module
features two holes which allow the module to be screwed to the carrier board. This is a preferred
solution for systems that are exposed to high vibrations. Spacers need to be placed between the
carrier board and the module in order to guarantee the required stacking height of the MXM3
connector. Please note that the screw holes of the Apalis modules are in a different location to
those in the mobile graphic cards.
Figure 66: Screw fixation
Suitable spacers are available from Würth Electronics (article number 9774030360 for the 3mm
and 9774080360 for 8mm distance). Please note, these spacers are soldered while the spacers
used on the evaluation board are press fitted. Therefore, the required PCB footprint is slightly
different. Please read the according Würth datasheet.
During the development process, it may be necessary to replace the module several times.
Screwing the module to the carrier board during development can be very inconvenient. The Apalis
module standard defines a mechanism of fixing the module to the carrier board with a clip
mechanism called MXM SnapLock. The clip is also used as holder of Mini PCI Express Cards. The
clips are available with different stacking height and need to be consistent with the stacking height
of the MXM3 connector. For the proposed stacking height of 3mm, a suitable MXM SnapLock clip is
the Molex 48099-5701. If MXM SnapLock is used, the spacers at the edge of the module and
under the CPU are optional if no cooling solution is required. As the MXM SnapLock connector can
be assembled as a normal SMD component while the spacers often need an additional production
process, the unique MXM SnapLock fixing method can be cost optimized solution also for volume
production.
Figure 67: SnapLock fixation