An electrical connector (100) adapted for being mounted on a mother board (900) includes a housing and a number of contact modules (21, 22) each having a wafer (210, 220) and a number of terminals insert molded with the wafer. The terminals include an upper terminal (211, 221) having an upper contact portion (2111, 2211), and a lower contact terminal (212, 222) having a lower contact portion (2121, 2221). The upper contact portion and the lower contact portion are separated from each other along a vertical direction to define a slot (214, 224) therebetween. The upper terminal and the lower contact terminal are secured in the wafer at two positions remote from each other along a mating direction perpendicular to the vertical direction, with the upper contact portion and the lower contact portion approaching close to each other along the mating direction.