Kontron COMe Starterkit Eval T2 - Manual (Page 195)

Mechanical Considerations
7.2. Heatspreader
An important factor for each system integration is the thermal design. The heatspreader acts as
a thermal coupling device to the Module. Usually It is a 3mm thick aluminum plate.
The heatspreader is thermally coupled to the CPU via a thermal gap filler and on some Modules
it may also be thermally coupled to other heat generating components with the use of additional
thermal gap fillers.
Although the heatspreader is the thermal interface where most of the heat generated by the
Module is dissipated, it is not to be considered as a heatsink. It has been designed to be used
as a thermal interface between the Module and the application specific thermal solution. The
application specific thermal solution may use heatsinks with fans, and/or heat pipes, which can
be attached to the heatspreader. Some thermal solutions may also require that the heatspreader
is attached directly to the systems chassis therefore using the whole chassis as a heat dissipater.
The main mechanical mounting solutions for systems based on COM Express Modules have
proven to be the 'top-mounting' and 'bottom-mounting' solutions. The decision as to which
solution will be used is determined by the mechanical construction and the cooling solution of the
customer's system. There are two variants of the heatspreader, one for each mounting
possibility. One version has threaded standoffs and the other has non-threaded standoffs (bore
hole). The following sections describe these two common mounting possibilities and the
additional components (standoffs, screws, etc...) that are necessary to implement the respective
solution.
The examples shown in the following Sections 7.2.1 'Top mounting' and 7.2.2. 'Bottom mounting'
are for heatspreader thermal solutions only. Other types of thermal solutions are possible that
might require other mounting methods.
PICMG ® COM Express ® Carrier Board Design Guide Rev. 2.0 / December 6, 2013
195/218