Structure to dampen barrel resonance of unused portion of printed circuit board via
View Patent ↗A printed circuit board includes a first trace, a second trace, and a first via. The first trace is in a first conductive layer. The second trace is in a second conductive layer. The first via interconnects the first trace and the second trace, and communicates a first signal from the first trace to the second trace through a third conductive layer. The third conductive layer has a higher impedance than the first conductive layer and the second conductive layer.
1. A method, comprising:
determining a length of an unused portion of a first via in a signal path of a printed circuit board;
determining a Nyquist frequency of a signal communicated on the signal path;
estimating a resonant frequency of the first via based on the length of the unused portion of the first via; and
in response to determining that the Nyquist frequency is approximately equal to the resonant frequency, plating a wall of the first via with a first conductive material having a higher resistivity than a second conductive material of the first via.
2. The method of claim 1 , wherein:
the printed circuit board includes a conductive layer;
the signal path includes a trace in the conductive layer coupled to the first via; and
the conductive layer is composed of a material other than the first conductive material.
3. The method of claim 1 , further comprising:
plating the wall of a second via of the printed circuit board with a material other than the first conductive material.
4. The method of claim 1 , wherein the first conductive material is tin.
5. The method of claim 1 , further comprising:
selecting the first conductive material based on a property of the signal.
6. A method, comprising:
providing a first trace in a first conductive layer of a printed circuit board;
providing a second trace in a second conductive layer of the printed circuit board;
plating a wall of a via with a third conductive layer to interconnect the first trace and the second trace, wherein the third conductive layer has a conductive material with a higher impedance than the first conductive layer and the second conductive layer; and
depositing a plating layer over the first trace and the third conductive layer, wherein the plating layer has a lower impedance than the conductive material of the third conductive layer.
7. The method of claim 6 , wherein prior to plating the wall of the first via, the method further comprising:
determining a length of an unused portion of the via in a signal path of the printed circuit board;
determining a Nyquist frequency of a signal communicated on the signal path;
estimating a resonant frequency of the via based on the length of the unused portion of the first via; and
determining that the Nyquist frequency is approximately equal to the resonant frequency.
8. The method of claim 6 , wherein a resistivity of the third conductive layer is greater than a resistivity of the first conductive layer and of the second conductive layer.
9. The method of claim 6 , further comprising:
communicating, by the first conductive layer, a first signal in a first conductive material; and
communicating, by the via, the first signal in a second conductive material.
10. The method of claim 9 , wherein the second conductive material comprises tin.
11. The method of claim 6 , further comprising:
selecting the third conductive material based on a property of the signal.
12. The method of claim 6 , wherein the via is a through via.
13. A method, comprising:
providing a first trace in a first conductive layer of a printed circuit board to provide a signal from a processor coupled to the printed circuit board;
providing a second trace in a second conductive layer of the printed circuit board;
determining a length of an unused portion of a first via in a signal path of the first conductive layer;
determining a Nyquist frequency of the signal communicated on the signal path;
estimating a resonant frequency of the via based on the length of the unused portion of the via; and
in response to determining that the Nyquist frequency is approximately equal to the resonant frequency, plating a wall of a via with a third conductive layer to interconnect the first trace and the second trace, wherein the third conductive layer has a conductive material with a higher impedance than the first conductive layer and the second conductive layer.
14. The method of claim 13 , further comprising:
depositing a plating layer over the first trace and the third conductive layer, wherein the plating layer has a lower impedance than the conductive material of the third conductive layer.
15. The method of claim 13 , wherein a resistivity of the third conductive layer is greater than a resistivity of the first conductive layer and of the second conductive layer.
16. The method of claim 13 , further comprising:
communicating, by the first conductive layer, a first signal in a first conductive material; and
communicating, by the via, the first signal in a second conductive material.
17. The method of claim 16 , wherein the second conductive material comprises tin.
18. The method of claim 13 , further comprising:
selecting the third conductive material based on a property of the signal.
19. The method of claim 13 , wherein the via is a through via.