An electrical connector (100) adapted for mounting on a printed circuit board (300) includes an insulative housing (1) and a number of conductive contacts (2) attached to the housing. The conductive contacts include a number of signal contacts (20) and a number of ground contacts (22). Each ground contact includes a pair of solder tails (30). The solder tails include retention type tails (32) positioned in selected positions of the insulative housing and non-retention type tails (34). Each retention type tail includes a pair of lateral bulge (36) in back to back manner for interfering with corresponding through hole of the printed circuit board (300).