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Enfora Enabler IIIG M2M
Modem Integration Guide
frequency applications. However, such thermal relief structures should be avoided for
applications where high current and/or high frequency is involved, such as those using the
Enabler Module. Depending on the frequency of operation, the long narrow thermal relief
traces between the pad and the ground plane act like an RF choke. These RF chokes
become higher impedance at harmonics of the fundamental frequency making it problematic
for high frequency suppression. This can make it difficult to pass type approval testing.
POOR RF thermal relief
Figure 2 - Example of a POOR RF Thermal Relief
If thermal relief is necessary, it is recommended that you use short, fat traces similar to those
shown in Figure 3. This will still provide a solderable connection, while providing a better RF
connection. Making them shorter also allows for a more continuous ground plane due to less
copper being removed from the area. It is also recommended to have ground vias around all
thermal relief of critical ground pins such as the five Enabler shield tabs.
GSM0308IG002
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Version 1.05 – 11/13/08
