An electrical connector includes an insulative housing having a top surface, a bottom surface opposite to the top surface and a number of receiving holes penetrated the top surface and the bottom surface, a number of terminals receiving in the receiving holes and a number of solder balls assembled to the receiving holes from a bottom surface thereof and contacting with the corresponding terminals. The receiving hole includes an inner wall and a core, the inner wall has a pair of ribs extending toward to the core and the movement of the solder ball in a vertical direction is limited by the pair of ribs in a vertical direction and the solder ball is positioned by the terminal.