1. A printed circuit board (PCB) comprising:a substrate having a surface; and
a pad group on the surface of the substrate, the pad group including at least two pads, each of the at least two pads including a first sub-pad portion and a second sub-pad portion, different and separate from the first sub-pad portion,
wherein the first sub-pad portion partially surrounds at least three sides of the second sub-pad portion; and
wherein the second sub-pad portion of one of the at least two pads protrudes from an end portion of the first sub-pad portion toward another pad of the at least two pads.