how many vias for copper area
On few RF evalution board I have found exposed copper areas (without solder mask) on top side. For what purpose it might have been put for?
Also found a guide line that "use a large number of vias to tie the front and backside ground plane regions together." How it will help the design( since the via will add indectance to the plane)?
Thank you.
Hi
Areas without soldermask is usually becuase you might want to tune the circuits yourself. It is easier than removing it yourself ;)
In RF PCB it is very important that you have good return path for the RF currents. So it is commen that a GND plane is used, so all RF components have access to GND. It is of cause important to add MANY vias as this will lower the inductance.
Regards
To help you solder ability for tuning.
For good grounding.
did not understood completley for the exposed copper thing ...my guess is that it is for the soldering of RF shield .
and this so-called via stitching is used to reduce radiation losses when stitched along RF shapes or when peppered across planes. it just acts like fences.
More parasitic inductors (vias) in parallel, means less resulting parasitic inductance.
Exposed copper is for test points, for calibration points, or for placing extra tuning components of the circuit.