When dealing with high speed designs, electronics engineers tend to match trace impedances to the utmost level possible. They take care of ground returns and crosstalk and try to minimise EMC while maximising Signal Integrity. Though with the increase in PCB complexity, this happens to be a challenge, they try and sacrifice many other parameters to achieve EMC and SI.

But, there is one aspect that most engineers overlook – the drilling of Vias. Vias, at very high frequencies behave very differently because their capacitance and inductance appear to matter and start impacting the amount of energy transferred. Does this mean we should not use vias at all at high frequencies? Not necessarily. But we need to design vias with equal care like the traces that connect to the vias. The impedance posed by a via is of equal importance as the trace impedance itself in order to maximise energy transfer.
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