Crossing conductive traces in a PCB

1. A printed circuit board comprising:

at least two conductive traces, each having a first portion and a second portion; and

a cross-over section that includes two electrically conductive portions, each connecting electrically to the first and second portions of a corresponding one of the conductive traces, such that the conductive traces in their first portions lie on opposite sides of each other as they do in their second portions, where the cross-over section includes a thru-hole via in which the two electrically conductive portions reside, each formed to carry one of the conductive traces from one layer of the printed circuit board to another layer.

2. The printed circuit board of claim 1 , where the printed circuit board has multiple layers, and where the electrically conductive portions are formed to carry the conductive traces from one layer to another layer.

3. The printed circuit board of claim 1 , where the electrically conductive portions are formed to rotate around a surface of the thru-hole via, such that a position at which each conductive trace exits the thru-hole via is offset by some angle from a position at which the trace enters the thru-hole via.

4. The printed circuit board of claim 3 , where the angle of the offset is 180 degrees for each of the conductive traces.

5. The printed circuit board of claim 3 , where the printed circuit board has multiple layers, and where electrically conductive portions are formed to rotate around the surface of the thru-hole via between two of the layers.

6. The printed circuit board of claim 5 , where one of the electrically conductive portions is formed to rotate around the surface of the thru-hole via between one pair of layers, and where another of the electrically conductive portions is formed to rotate around the surface of the thru-hole via between another pair of layers.

7. The printed circuit board of claim 6 , where each of the electrically conductive portions is formed to rotate around the surface of the thru-hole via by 180 degrees.

8. The printed circuit board of claim 1 , where the electrically conductive portions are formed to rotate continuously from one end of the thru-hole via to its other end.

9. The printed circuit board of claim 8 , where the electrically conductive portions are formed to make a total rotation of 180 degrees.

10. The printed circuit board of claim 1 , where the printed circuit board has multiple layers and the thru-hole via penetrates all of the layers.

11. The printed circuit board of claim 1 , where the conductive traces carry a differential signal pair.

12. At least two conductive traces, each having a first portion and a second portion; and

a cross-over section that includes two electrically conductive portions, each connecting electrically to the first and second portions of a corresponding one of the conductive traces, such that the conductive traces in their first portions lie on opposite sides of each other as they do in their second portions where the cross-over section includes a flexible circuit mounted such that it is twisted on itself.

13. The printed circuit board of claim 12 , where the cross-over section also includes a thru-hole via into which the flexible circuit is mounted.

14. The printed circuit board of claim 13 , where the flexible circuit connects mechanically and electrically to electrically conductive pads formed at each end of the thru-hole via.

15. The printed circuit board of claim 14 , where the conductive traces also connect electrically to the electrically conductive pads.

16. The printed circuit board of claim 12 , where the flexible circuit and the first and second portions of the conductive traces all lie on one layer of the printed circuit board.

17. The printed circuit board of claim 12 , where the flexible circuit is twisted one-half turn.