An electrical connector (100) includes an insulating housing (240) and a number of plate wafers (200) vertically stacked behind the insulating housing (240). Each of the plate wafers (200) includes a frame (22) and a plurality of conductive contacts (23) secured by said frame (22). The conductive contacts (23) of each plate wafer (200) have press-fit portions (236) disposed along a first length. The frame (22) forms a rib (221) extending over the first length along said lower edge of the frame (22) so that a tooling (600) can press on a top face of the rib (221) when the electrical connector (100) is mounted onto the printed circuit board. The insulating housing (240) forms a plurality of engaging portions (244) extending a second length backwardly from the rear face (248) above said rib (221). The second length does not overlap the first length in a vertical direction, so that the tooling (600) can be downwardly inserted between adjacent wafers (200) and press on a top face of the rib (221) of the frame (22).