Through-hole-vias in multi-layer printed circuit boards

1. A method of manufacturing a multi-layer printed circuit board (PCB) comprising:

depositing upon layers of laminate printed circuit traces;

joining the layers of laminate;

drilling at least one via hole through the layers of laminate;

placing in the via hole a via conductor comprising a used portion and an unused portion, the via conductor comprising copper coated with a second metal having a conductivity lower than the conductivity of copper;

wherein both the used portion and the unused portion of the via conductor comprise copper, and

only the unused portion of the via conductor is coated with a metal having a conductivity lower than the conductivity of copper.

2. The method of claim 1 further comprising:

forming the used portion of the via conductor so as to conduct an alternating current signal from a trace on one layer of the PCB to a trace on another layer of the PCB,

the alternating current signal characterized by a frequency high enough to demonstrate skin effect, moving the alternating current toward the surface of the via conductor.

3. The method of claim 1 further comprising:

forming the unused portion of the via conductor with no connection to any further trace,

the unused portion of the via conductor implementing a resonant stub effecting an insertion loss of the alternating current signal centered on a resonant frequency,

the metal having a conductivity lower than the conductivity of copper increasing resistive dampening of resonance and reducing the insertion loss.

4. The method of claim 1 wherein the metal having a conductivity lower than the conductivity of copper is iron.

5. The method of claim 1 wherein the metal having a conductivity lower than the conductivity of copper is nickel.