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User Manual
1.6 Mechanical Distortion of PCB
For thermal heat dissipation the heat sink needs to have a good mechanical contact to the CPU housing which means the heat sink should be mounted
such that there is some mechanical stress applied. The higher the force applied the better the thermal resistance and consequently the better the
thermal cooling. This pressure may result in a slight mechanical bending of the SMARC module PCB.
Production tolerance, material deviation and thermal expansion lead to a range of possible pressure range and bending. A negative pressure with an
air gap between the heat spreader and the chip case needs to be avoided and likewise too much distortion.
Component types and their distance to the heat spreader mounting holes need to be considered.
Referring to data sheets of the relevant parts and referring to AEC-Q200 the bending needs to be less than 1mm over 90mm. (1.11%)
→
0.75mm
Figure 1-4: Distance between mounting holes
68mm