Electronic – Via inside decoupling capacitor pad

decoupling-capacitorpcb-design

If I place my decoupling capacitor (more or less) like shown in the figure:
enter image description here

I wonder: can the vias be inside the pads? (one via inside each).

Two advantages I can see are: (1) we avoid the inductance of the trace from the capacitor pad to the via, since we eliminate that trace. And (2) we save space on the board.

One inconvenience I can see is that it will disrupt the estimates of the amount of solder paste one has to place. For "manual" reflow solder projects, one can certainly compensate for it. Is this a real problem for automated soldering/assembly setups?

Are there any other reasons to avoid this? (seems like an interesting trick with certain advantages — the fact that I can't find a single reference to it when searching online tells me that there's probably some fundamental reason why this should not be done)

Best Answer

You are correct about the advantages of lower inductance and saving space. However, via in pad adds cost to the fabrication of PCB because it requires that that the via be filled and capped to maintain a flat continuous SMT pad.