Patent ID: 8143528

Claim:
A printed circuit board, comprising: a signal layer configured for signal transmission; a reference layer parallel to the signal layer, and sandwiching an insulation layer with the signal layer; a transmission line located on the signal layer, and configured for transmitting a transmission signal in a first direction; a probing pad located on the transmission line and configured for testing the signal in response to a contact with a probe, wherein a center of the probing pad is located on a centerline of the transmission line, and a diameter of the probing pad is greater than a width of the transmission line; and two aligned slots defined in the reference layer and extending toward each other from opposite edges of the reference layer to divide the reference layer into two parts, leaving a connecting portion between the slots to connect the separated two parts of the reference layer, wherein a length of the connecting portion is substantially equal to the diameter of the probing pad; wherein the slots are in vertical alignment with the probing pad, extend along a second direction perpendicular to the first direction, and are configured for cutting off a return path of the transmission signal in the reference layer, and wherein the connecting portion is in vertical alignment with the center of the probing pad and parallel to the first direction, and acts as a return path for the transmission signal in the reference layer, thereby reducing a capacitance effect caused by the probing pad.