Advantech SOM-Express Design Guide
104 Chapter 8 Heat Sink Recommended Design
Tolerances (unless otherwise specified):
Z (height) dimensions should be ±0.8mm [±0.031”] from top of Carrier Board to top of
heat-spreader.
Heat-spreader surface should be flat within 0.2mm [.008”] after assembly.
Interface surface finish should have a maximum roughness average (Ra) of 1.6μ
m[63μin].
The critical dimension in Figure 8-3 is the module PCB bottom side to heat-spreader
top side. This dimension shall be 13.00mm±0.65mm [±0.026”].
Figure 8-3 shows a cross section of a module and heat-spreader assembled to a
Carrier Board using the 5mm stack height option. If 8mm Carrier Board connectors
are used, the overall assembly height increases from 18.00mm to 21.00mm.
All dimensions are in mm. X-Y tolerances shall be ±0.3mm [±0.012”]
