Techniques and mechanisms to provide a compact arrangement of vias extending through at least a portion of a printed circuit board (PCB) or other substrate. In an embodiment, the substrate includes a dielectric material and a sidewall structure forming a hole region that extends at least partially through the dielectric material. The hole region adjoins each of a first via and a second via, and is also located between the first via and second via. In another embodiment, the first via is coupled to exchange a first signal of a differential signal pair, and the second via is coupled to exchange a second signal of the same differential signal pair.