The electrical connector (50) includes an insulative housing (51) defining a mounting face (501) for mounting onto a printed circuit board (10) and a mating face (502) opposite to the mounting face, a plurality of contacts (52) received in the insulative housing, an insulator (20) mounted to an underside of the printed circuit board, a back panel (30) attached to the insulator, and a plurality of fastening elements (40) mechanically interconnecting the back panel, the insulator and the insulative housing onto opposite sides of the printed circuit board. The insulator has a plurality of pairs of guiding posts (23) extending oppositely towards the back panel and the printed circuit board. The back panel defines a plurality of guiding holes (33) aligned with holes (14) on the printed circuit board for receiving corresponding guiding posts.