An interposer connector assembly includes a substrate, conductive pads, and contacts. The substrate has opposite first and second sides with a conductive via extending through the substrate. The conductive pads are mounted to the first and second sides of the substrate and electrically coupled with each other by the via. The contacts are electrically joined with the conductive pads on the first and second sides of the substrate. The contacts protrude from the substrate to outer ends that are configured to engage conductive members of electronic packages that mate with the first and second sides of the substrate. A differential electrical impedance characteristic of a conductive pathway extending from the outer end of one of the contacts to the outer end of another one of the contacts is at least 65 Ohms.