Quectel EG91 Series Hardware Design page 81

 Do not place components on the opposite side of the PCB area where the module is mounted, in
order to facilitate adding of heatsink when necessary.
 Do not apply solder mask on the opposite side of the PCB area where the module is mounted, so as
to ensure better heat dissipation performance.
 The reference ground of the area where the module is mounted should be complete, and add ground
vias as many as possible for better heat dissipation.
Make sure the ground pads of the module and PCB are fully connected.

According to customers' application demands, the heatsink can be mounted on the top of the module,

or the opposite side of the PCB area where the module is mounted, or both of them.
 The heatsink should be designed with as many fins as possible to increase heat dissipation area.
Meanwhile, a thermal pad with high thermal conductivity should be used between the heatsink and
module/PCB.
The following shows two kinds of heatsink designs for reference and customers can choose one or bothof
them according to their application structure.
Figure 39: Referenced Heatsink Design (Heatsink at the Top of the Module)
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LTE Module Series
EG91 Hardware Design